JP6684679B2 - Control device for power converter for distributed power supply, distributed power supply system having the control device, and control method for power converter for distributed power supply - Google Patents

Description

  The present disclosure relates to a control device and a control method for controlling a power converter for connecting a distributed power supply to a power system, and further relates to a distributed power supply system including such a control device.

  For example, when the renewable energy power generation system is connected to the power grid, the power generation output may greatly change due to weather conditions and the stability of the power grid may be affected. Therefore, each of the plurality of power generation systems constituting the distributed power supply system outputs the active power output to the power system in order to maintain the system voltage or the system frequency of the power system in the vicinity of the predetermined rated voltage or rated frequency. And reactive power may be properly controlled.

  For example, the inventions described in Patent Document 1 and Patent Document 2 increase the output amount of active power when the grid frequency of the power system interconnected with the wind turbine generator decreases, thereby increasing the grid frequency and The following measures have been taken to stabilize it. Patent Document 1 estimates the power generation output of a virtual generator that varies according to the fluctuation of the system frequency by simulating the dynamic characteristics of control of the system frequency by the virtual generator, and wind power generation based on the result of the estimation. Disclosed is a technique for adjusting the power output of the machine. Further, in Patent Document 2, if the rotation speed of the wind power generator is equal to or higher than a predetermined rotation speed, the load torque of the wind turbine rotor is increased by controlling the inverter device that connects the wind power generator and the power system. Then, the technique of converting a part of the inertia energy of the wind turbine rotor into a power generation output is disclosed.

  In addition, in the invention described in Patent Document 3, in order to raise the system voltage when the voltage of the power system drops, the secondary side voltage of the transformer provided at the interconnection point between the generator and the power system is adjusted. By doing so, control is performed to increase the reactive power supplied from the generator to the power system.

JP, 2014-057492, A International Publication No. 2011/016278 International Publication 2014/021152

  However, in the recent distributed power supply system, while it is mainstream that the power output to the power grid is controlled by the power converter that connects the generator to the power grid, while patents are applied to such distributed power supply system. The following problems occur when the power control described in Documents 1 to 3 is applied.

  The power converter described above is realized, for example, as a bidirectional inverter circuit composed of power semiconductor elements. However, when excessive power is output to the power converter, an excessive current causes the elements inside the circuit to overheat. Malfunction or burn out. Therefore, in a power converter realized by a bidirectional inverter circuit, the inverter capacity is specified as part of the equipment specifications, and the inverter capacity corresponds to the upper limit of apparent power that can be output from the power converter to the power system. To do.

  In other words, the apparent power obtained from the active power and the reactive power output from the power converter to the power grid does not exceed the capacity of the power converter, and is output to the power grid via the power converter by the power generation system. Active and reactive power must be controlled. Therefore, if the active power and the reactive power output from the power converter to the power system according to the power control methods described in Patent Documents 1 to 3 are excessive with respect to the above-described inverter capacity, an excessive current causes the internal power converter The element may overheat, resulting in malfunction or burning.

  As described above, in at least one embodiment according to the present invention, within the limited capacity range of the power converter, the power converter outputs to the power system so as to suppress frequency fluctuations and voltage fluctuations in the power system. An object of the present invention is to obtain a control device and a control method capable of appropriately controlling active power and reactive power.

(1) According to some embodiments of the present invention, a control device for controlling a power converter for matching power from a distributed power source with a power system includes:
An active power control unit for controlling the power converter to adjust active power supplied from the distributed power supply to the power system;
A reactive power control unit for controlling the power converter to adjust the reactive power supplied from the distributed power supply to the power system,
Based on at least one of the system voltage or system frequency of the power system,
The maximum reactive power that can be output by the power converter when the first active power command value is given to the active power control unit and the power converter outputs the active power corresponding to the first active power command value. A first control mode in which the following first reactive power command value is given to the reactive power control unit,
The second active power command value is given to the reactive power control unit, and the maximum active power that can be output by the power converter when the power converter outputs the reactive power corresponding to the second reactive power command value. A second control mode in which the following second active power command value is given to the active power control unit,
A control mode switching unit configured to switch the control mode between a plurality of modes including,
It is characterized by including.

  According to the configuration of (1) above, in the first control mode, the maximum reactive power that can be output by the power converter when the power converter outputs active power corresponding to the first active power command value from the power converter. The following first reactive power command value is determined. Further, in the second control mode, the second active power that is equal to or less than the maximum active power that can be output by the power converter when the power converter outputs the reactive power corresponding to the second reactive power command value from the power converter. Determine the command value.

  Therefore, in both the first control mode and the second control mode, the active power and the reactive power output from the power converter to the power system are prevented from exceeding the capacity of the power converter from the power converter. It is possible to control active power and reactive power output to the power grid. In addition, the control device according to the configuration of (1) above has a control mode between a plurality of modes including a first control mode and a second control mode according to at least one of the system voltage or the system frequency of the power system. Can be switched and executed. From the above, according to the configuration of the above (1), the power converter is changed to the power system so as to suppress the frequency fluctuation and the voltage fluctuation in the power system as much as possible within the limited capacity range of the power converter. The output active power and reactive power can be controlled appropriately.

  (2) In one exemplary embodiment, in the configuration of (1), the control mode switching unit has a system voltage of the power system within a first specified range or a system frequency of the power system. Is configured to switch the control mode depending on whether or not is within the second specified range.

  The maximum range in which the voltage deviation from the rated voltage is allowed due to voltage fluctuations and the maximum range in which the frequency deviation from the rated frequency is allowed due to frequency fluctuations are stipulated as grid interconnection rules for the power system connected to the power generation system. Sometimes. In this case, if the system voltage of the power system is within the first specified range, the voltage fluctuation is acceptable, and if the system frequency of the power system is within the second specified range, the frequency fluctuation is acceptable.

  Therefore, according to the configuration of the above (2), depending on which of the frequency fluctuation and the voltage fluctuation in the power system is unacceptable, the unacceptable one within the limited capacity range of the power converter. Active power and reactive power output from the power converter to the power system can be controlled so as to suppress fluctuations. From the above, according to the configuration of the above (2), in order to suppress frequency fluctuations and voltage fluctuations in the power system depending on the cause of system disturbance, within the limited capacity of the power converter, The active power and the reactive power output from the power converter to the power system can be controlled more appropriately.

(3) In an exemplary embodiment, in the configuration of (2) above, the control mode switching unit is
When the system voltage deviates from the first specified range, the controller is operated in the second control mode, and when the system frequency deviates from the second specified range, the controller is controlled by the first control. It is characterized in that it is configured to operate in a mode.

  According to the configuration of (3), when the voltage fluctuation out of the allowable range of the voltage fluctuation and the frequency fluctuation of the power system, the second control mode defined in (1) above is switched to and the frequency fluctuation is allowed. When it deviates from the range, it becomes possible to switch to the first control mode defined in the above (1). In this case, the first control mode is effective in suppressing frequency fluctuation because it corresponds to power control in which active power is preferentially output to the power system within the limited capacity of the power converter. On the other hand, the second control mode is effective in suppressing voltage fluctuation because it corresponds to power control in which reactive power is preferentially output to the power system within the limited capacity of the power converter.

  That is, according to the configuration of (3) above, either the active power or the reactive power is preferentially prioritized in the power system within the limited capacity of the power converter according to the frequency fluctuation and the voltage fluctuation in the power system. Output to the electric power system, the active power and the reactive power output from the power converter can be appropriately controlled. From the above, according to the configuration of the above (3), depending on which of the frequency fluctuation and the voltage fluctuation in the power system is unacceptable, the one which is not allowable within the limited capacity of the power converter. It is possible to more appropriately control the active power and the reactive power output from the power converter to the power system so as to suppress the fluctuation of

(4) In one exemplary embodiment, in the configuration of (2) or (3), the control mode switching unit has the system voltage deviating from a first specified range, and the system frequency is When deviating from the second specified range, the first control is performed based on the magnitude relationship between the deviation ratio of the system voltage from the first specified range and the deviation ratio of the system frequency from the second specified range. It is characterized in that it is configured to select either one of the mode and the second control mode.
In the present specification, the “deviation ratio” means the ratio of the deviation amount from the specified range to the size of the specified range (the first specified range or the second specified range).

  In the configuration of (4) above, when both the voltage fluctuation and the frequency fluctuation of the power system are unacceptable, either the system voltage or the system frequency is significant in the degree of deviation from the allowable range defined by the system interconnection regulation. Either the first control mode or the second control mode can be selected depending on whether or not. That is, depending on whether the system voltage or the system frequency is significant at the extent of deviation from the allowable range defined by the system interconnection regulation, either the active power or the reactive power is selected within the limited capacity of the power converter. It is possible to select whether to preferentially output to the power system.

  From the above, according to the configuration of the above (4), within the limited capacity range of the power converter, in order to suppress the fluctuation of the frequency fluctuation and the voltage fluctuation in the power system, whichever is more significant, The active power and the reactive power output from the power converter to the power system can be controlled more appropriately.

  (5) In one exemplary embodiment, in the configuration of (2) to (4), the control mode switching unit has the system voltage deviating from a first specified range, and the system frequency is When deviating from the second prescribed range, the deviation is determined according to a deviation ratio of the system voltage from the first specified range and a deviation ratio of the system frequency from the second specified range. The capacity of the power converter is proportionally divided into a first capacity for active power and a second capacity for reactive power, the active power is limited within the range of the first capacity, and the reactive power is controlled by the second capacity. Is configured to limit within the range of.

  In the above configuration (5), the deviation ratio of the voltage fluctuation and the frequency fluctuation of the power system from the allowable range defined by the grid interconnection regulation is evaluated, and the relative ratio of the two deviation ratios evaluated for the voltage fluctuation and the frequency fluctuation, respectively. Are seeking. In addition, in the configuration of (5) above, the relative ratio between the output amount of active power and the output amount of reactive power that can be output from the power converter to the power system to the maximum extent is set according to the relative ratio of the deviation ratio described above. is doing.

  From the above, according to the configuration of the above (5), when both the voltage fluctuation and the frequency fluctuation of the power system deviate from the permissible range determined by the grid interconnection regulation, the power is converted from the power converter as follows. It is possible to control the output amount of active power and reactive power output to the grid. That is, according to the configuration of the above (5), the effective power for suppressing the voltage fluctuation and the frequency fluctuation as much as possible according to the contribution rate of the voltage fluctuation and the frequency fluctuation contributing to the system disturbance of the power system, respectively. The output amount of reactive power can be controlled appropriately.

(6) In an exemplary embodiment, in the configurations of (1) to (5), the maximum reactive power in the first control mode and the maximum active power in the second control mode are calculated. Further equipped with a limit processing unit of
The limit processing unit,
When the control device operates in the first control mode, the apparent power in the power converter is the capacity of the power converter when the power converter outputs the active power corresponding to the first active power command value. Set the maximum reactive power to a value that matches
During operation of the control device in the second control mode, the apparent power in the power converter matches the capacity when the power converter outputs the reactive power corresponding to the second reactive power command value. It is configured to set the maximum active power to a value.

  According to the configuration of (6) above, in the first control mode and the second control mode, the above-mentioned maximum reactive power and maximum active power are respectively set so that the apparent power described above has a value that matches the capacity of the power converter. By setting, it is possible to reliably prevent overload of the power converter while controlling active power and reactive power for stabilizing the system.

(7) In one exemplary embodiment, in the configuration of (6), the distributed power source includes one or more wind power generation units each including a wind power generator,
MPPT that receives wind speed information indicating the wind speed from each of the wind power generation units and outputs a first control signal for controlling the wind power generator at an optimum operating point according to the wind speed based on at least the wind speed information. Maximum Power Point Tracking controller),
A governor control unit that outputs a second control signal for maintaining a system frequency of the power system constant;
An adder that determines the first active power command value based on a control signal obtained by adding the first control signal and the second control signal and outputs the first active power command value to the limit processing unit;
Is further provided.

  In the configuration of (7), the MPPT control unit outputs the first control signal for controlling the wind power generator at the optimum operating point according to the wind speed based on the wind speed information. Here, in MPPT control, the optimum operating point according to the wind speed is the operating point for operating the wind power generator so that the active power output by the wind power generator is maximized under a given wind speed. is there. Therefore, the MPPT control unit can output the first control signal for controlling the wind power generator based on the wind speed information so that the active power from the wind power generator is maximized.

  Further, in the above configuration (7), the governor control unit outputs the second control signal for maintaining the system frequency of the power system constant. Here, in the governor control, the number of revolutions or the torque of the generator is appropriately controlled so as to maintain the grid frequency constant in response to the fluctuation of the grid frequency of the power grid. Therefore, the governor control unit can output the second control signal for controlling the rotation speed or the torque of the generator so as to maintain the grid frequency constant in response to the fluctuation of the grid frequency of the power grid. .

  As described above, in the above configuration (7), the first control signal for controlling the wind power generator and the system frequency are controlled to be constant so that the active power from the wind power generator is maximized based on the wind speed information. The first active power command value is determined based on the control signal obtained by adding the second control signal for controlling the rotation speed or torque of the generator. As a result, in the above configuration (7), when the first control mode is selected, the power converter is controlled so as to output to the power system an amount of active power that is optimum for stabilizing the system frequency of the power system. be able to.

(8) In one exemplary embodiment, in the configuration of (6) or (7), the distributed power source includes one or more wind power generation units each including a wind power generator,
An AVR control unit that determines the second reactive power command value for maintaining the power generation end voltage of the wind power generator constant and outputs the second reactive power command value to the limit processing unit;
Is further provided.

  According to the above configuration (8), the AVR control unit determines the second reactive power command value for maintaining the power generation end voltage of the wind power generator constant, and outputs it to the limit processing unit. Therefore, according to the configuration of the above (8), when the second control mode is selected, the power converter is controlled so as to output the reactive power of the optimum amount for stabilizing the grid voltage of the power grid to the power grid. can do.

  Further, in the above configuration (6) or (7), it is desirable that the first reactive power command value be a value that maintains the system voltage of the power system constant. On the other hand, the generator end voltage of the wind power generator is easier for power supply side operators to measure than the grid voltage of the power grid, and additional equipment and arrangements for receiving grid voltage measurement data from the grid Is also unnecessary.

  Therefore, in the above configuration (8), the reactive power to be output from the power converter to the power system is controlled based on the power generation end voltage. When reactive power is controlled based on the voltage at the generator end, the convergence of the system voltage of the power system does not start unless a certain response delay elapses after the voltage at the generator end converges to a constant value. Since the response delay is sufficiently small, there is no problem in practical use. Therefore, according to the configuration of the above (8), the active power is adjusted so as to be within the capacity range of the power converter based on the power generation end voltage which is easier for the power supply supplier to measure than the system voltage of the power system. And, the output amount of the reactive power can be controlled with an accuracy that does not pose a problem in practical use.

(9) In one exemplary embodiment, in the configurations of (1) to (8), the distributed power source includes a plurality of wind power generation units each including a wind power generator, and the plurality of wind power generation units are provided. , At least one first unit and one or more second unit other than the first unit and having a wind speed lower than that of the first unit, further comprising a unit classification unit,
The control mode switching unit,
For the first unit, when the system voltage of the power system is within a first specified range, the power converter is controlled in the first control mode as a main control mode, while the system voltage is the first control mode. When the power converter deviates from the specified range, the power converter is controlled in the second control mode as the sub-control mode,
Regarding the second unit, when the system frequency of the power system is within the second specified range, the power converter is controlled in the second control mode as the main control mode, while the system frequency is the first control mode. It is characterized in that it is configured to control the power converter in the first control mode as a sub-control mode when it deviates from the two specified ranges.

  In the above configurations (1) to (8), whether or not at least one of the system voltage and the system frequency of the power system is unstable, even when the distributed power source is composed of a plurality of wind power generation units. According to the above, uniform control mode switching is performed in all wind power generation units. For example, if the grid frequency is unstable, all wind power generation units will switch to the first control mode, and if the grid voltage is unstable, all wind power generation units will switch to the second control mode.

  However, when the wind speed is different for each of the multiple wind power generation units, the wind power generation unit with a high wind speed can maintain the rotation speed and output of the generator high, so that the amount of active power output from such a wind power generation unit is invalidated. Power should be given priority over electricity and should be increased aggressively. Therefore, in the above configuration (9), the first control mode is set to the main control mode for the first unit having a relatively high wind speed, and active power is preferentially output when the system voltage is stable. On the contrary, in the second unit where the wind speed is relatively low, the number of revolutions of the generator is low, and the wind energy that can be extracted as the power generation output is scarce, so that it is not possible to expect much active power to be obtained from the second unit. Therefore, in the above configuration (9), for the second unit, the second control mode is set to the main control mode in preparation for a voltage fluctuation in the power system, and reactive power is preferentially output when the system frequency is stable. I am trying to let you.

  As described above, according to the configuration of (9), the output control of electric power is performed for each wind power generation unit within the range of the capacity of the power converter, and the wind power generation units relatively move according to the wind speed distribution in the distributed power source. As much active power as possible can be extracted from the unit set including the first unit having a high wind speed. Further, according to the configuration of (9), since it is not possible to expect a large amount of active power from the unit set including the second unit having a relatively low wind speed, reactive power is stabilized for system voltage stabilization. The output can be positively made.

  (10) In an exemplary embodiment, in the configuration of (9), the deviation ratio of the system voltage from the first specified range and the deviation ratio of the system voltage from the first specified range are large or small. It is characterized by further comprising an allocation number determining unit for adjusting the unit allocation number of the first unit and the unit allocation number of the second unit based on the relationship.

  In the configuration of the above (10), the deviation ratio from the allowable range defined by the grid interconnection regulation is evaluated for the voltage fluctuation and the frequency fluctuation of the power system, and the relative ratio of the two deviation ratios evaluated for the voltage fluctuation and the frequency fluctuation, respectively. May be requested. By doing so, in the configuration of (10), the unit allocation number of the first unit that preferentially outputs active power when the system is stable and the unit of the second unit that preferentially outputs reactive power when the system is stable. The relative ratio with the assigned number is set according to the relative ratio of the deviation ratio described above.

  From the above, according to the configuration of the above (10), in order to suppress the voltage fluctuation and the frequency fluctuation as much as possible, the voltage fluctuation and the frequency fluctuation respectively correspond to the contribution ratio to the system disturbance of the power system. The relative ratio between the unit allocation number of one unit and the unit allocation number of the second unit can be appropriately adjusted. Therefore, according to the configuration of the above (10), in the entire distributed power supply including the plurality of wind power generation units, the fluctuations of the system voltage and the system frequency are suppressed in consideration of the contribution rate to the system disturbance. It is possible to output the necessary and sufficient active power and reactive power.

(11) In an exemplary embodiment, in the configuration of (10), the allocation number determination unit is
The provisional number of the first units is determined according to the deviation ratio of the system frequency from the first specified range, and the provisional number of the second units is determined according to the deviation ratio of the system voltage from the second specified range. Decide
When the total of the provisional number of the first unit and the provisional number of the second unit is less than or equal to the total number of the plurality of wind power generation units, the provisional number of the second unit is assigned to the unit allocation number of the second unit. Is set, and the number obtained by subtracting the provisional number of the second unit from the total number of the plurality of wind power generation units is set as the unit allocation number of the first unit.

  In the configurations (9) and (10), the first unit that preferentially outputs active power when the grid is stable contributes to frequency stabilization of the power grid, and outputs the reactive power preferentially when the grid is stable. The two units contribute to voltage stabilization of the power system. Therefore, in the above configuration (11), the provisional numbers of the first unit and the second unit are respectively determined according to the abnormalities of the system voltage and the system frequency, and the remaining wind power generation except the provisional number of the second unit is performed. All of the number of units is set to the unit allocation number of the first unit. As a result, according to the configuration of (11), by allocating as many units as possible to the first unit that preferentially outputs active power in the main control mode, as much active power as possible is obtained. It is possible to secure the required number of the second units while supplying the power to the power system.

(12) In an exemplary embodiment, in the configuration of (9), the allocation number determination unit is
The provisional number of the first units is determined according to the deviation ratio of the system frequency from the first specified range, and the provisional number of the second units is determined according to the deviation ratio of the system voltage from the second specified range. Decide
When the deviation ratio of the system voltage from the second specified range is larger than the deviation ratio of the system frequency from the first specified range, the provisional number of the second units is set to the unit allocation number of the second unit. , A number obtained by subtracting the provisional number of the second unit from the total number of the plurality of wind power generation units is set as the unit allocation number of the first unit,
If the deviation ratio of the system voltage from the second specified range is less than or equal to the deviation ratio of the system frequency from the first specified range, the provisional number of the first units is set to the unit allocation number of the first unit. Then, the number obtained by subtracting the provisional number of the first unit from the total number of the plurality of wind power generation units is set as the unit allocation number of the second unit,
It is characterized by

  In the configuration of (12) above, the number of unit allocations of the first unit and the second unit is set to the following depending on which of the system voltage and the system frequency is significant in the degree of deviation from the allowable range defined by the system interconnection regulation. To decide. That is, if the deviation of the system frequency is larger, the unit allocation number of the first unit that contributes to frequency stabilization of the power system is preferentially secured among the total number of the wind power generation units, and the remaining wind power The number of power generation units is the unit allocation number of the second unit. On the contrary, if the degree of deviation of the system voltage is greater, the number of assigned units of the second unit that contributes to the voltage stabilization of the power system out of the total number of the plurality of wind power generation units is preferentially secured and remains. The number of wind power generation units is the unit allocation number of the first unit. As described above, according to the configuration of (12) above, the number of assigned units of the first unit and the units of the second unit are controlled so as to suppress the fluctuation of the frequency fluctuation and the voltage fluctuation in the power system, whichever is more affected. The number of allocations can be adjusted appropriately.

  (13) A distributed power supply system according to some embodiments of the present invention includes a distributed power supply, a power converter for matching the power from the distributed power supply with a power system, and a power converter for controlling the power converter. The control device according to any one of (1) to (12) above is provided.

  As described in (1) to (12) above, the control device included in the distributed power supply system of (13) described above has active power and reactive power output from the power converter to the power system as the capacity of the power converter. On the other hand, the active power and the reactive power output from the power converter to the power system can be controlled so as not to be excessive. As described above, according to the configuration of (13), the range of the limited capacity of the power converter provided at the grid interconnection point is limited in order to suppress the frequency fluctuation and the voltage fluctuation in the power system as much as possible. It is possible to realize a distributed power supply system capable of appropriately controlling active power and reactive power output from the distributed power supply to the power system.

(14) According to some embodiments of the present invention, a method of controlling a power converter for matching power from a distributed power source to a power system includes:
Controlling the power converter to regulate active power supplied from the distributed power source to the power grid;
Controlling the power converter to regulate reactive power supplied from the distributed power source to the power grid;
Switching the control mode of the power converter based on at least one of a system voltage or a system frequency of the power system,
The control mode of the power converter is
The maximum reactive power that can be output by the power converter when the first active power command value is given to the active power control unit and the power converter outputs the active power corresponding to the first active power command value. A first control mode in which the following first reactive power command value is given to the reactive power control unit,
The second active power command value is given to the reactive power control unit, and the maximum active power that can be output by the power converter when the power converter outputs the reactive power corresponding to the second reactive power command value. A second control mode in which the following second active power command value is given to the active power control unit,
It is characterized in that it can be switched between a plurality of modes including.

  In the method of (14), in the first control mode, when the power converter outputs active power corresponding to the first active power command value from the power converter, the maximum reactive power that can be output by the power converter is less than or equal to the maximum reactive power. A first reactive power command value that satisfies the above is determined. Further, in the second control mode, the second active power that is equal to or less than the maximum active power that can be output by the power converter when the power converter outputs the reactive power corresponding to the second reactive power command value from the power converter. Determine the command value.

  Therefore, in both the first control mode and the second control mode, the active power and the reactive power output from the power converter to the power system are prevented from exceeding the capacity of the power converter from the power converter. It is possible to control active power and reactive power output to the power grid. Moreover, according to the method of (14), the control mode is switched between a plurality of modes including the first control mode and the second control mode according to at least one of the system voltage and the system frequency of the power system. Can be executed. From the above, according to the method of (14), for example, depending on which of the frequency fluctuation and the voltage fluctuation in the power system is larger, the limit of the power converter is limited in order to suppress these fluctuations. The active power and the reactive power output from the power converter to the power system can be appropriately controlled within the range of the determined capacity.

  From the above, according to some embodiments of the present invention, within the limited capacity range of the power converter, output from the power converter to the power system so as to suppress frequency fluctuations and voltage fluctuations in the power system. It is possible to obtain a control device and a control method capable of appropriately controlling the effective power and the reactive power that are generated.

It is a figure which illustrates the structure of the wind power generation unit which concerns on some embodiment. It is a figure explaining the operation | movement of the limit process part in a wind power generation unit. It is a figure which shows the relationship between the capacity of a power converter, active power, and reactive power. It is a figure which shows the detail of the adjustment process of the electric power command value by a limit process part. It is a figure which shows switching between the 1st control mode based on the fluctuation | variation of system voltage, and a 2nd control mode. 6 is a flowchart for explaining an operation of a control mode switching unit switching between a first control mode and a second control mode according to a change in a power generation end voltage. It is a flowchart for demonstrating the operation | movement which a control mode switching part switches between a 1st control mode and a 2nd control mode according to the fluctuation | variation of system frequency. It is a flowchart for demonstrating the operation | movement which a control mode switching part switches between a 1st control mode and a 2nd control mode according to both a system frequency and a power generation terminal voltage. FIG. 3 is a diagram showing an exemplary distributed power supply including a plurality of wind power generation units. It is a figure which shows switching of the main control mode and sub-control mode based on the power curve of a wind power generation unit. It is a figure which illustrates the structure of the central control device for carrying out integrated control of the some wind power generation unit which comprises a distributed power supply. It is a flow chart which shows a procedure which classifies a plurality of wind power generation units which constitute a distributed power generation into a 1st unit and a 2nd unit according to wind conditions. It is a graph which shows the relationship between the fluctuation range of system voltage and system frequency, and the provisional number of 1st units and 2nd units.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative positions, and the like of the components described as the embodiments or shown in the drawings are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. Absent.
For example, expressions such as "identical", "equal", and "homogeneous" that indicate that they are in the same state are not limited to strict equality, but also include tolerances or differences in the degree to which the same function is obtained. It also represents the existing state. On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one element are not exclusive expressions excluding the existence of other elements.

  Hereinafter, first, a configuration of a control device for controlling a power converter for a distributed power supply according to some embodiments and a configuration of a wind power generation unit including the control device as a component will be described with reference to FIG. 1. . Next, the function and power control operation of each unit constituting the control device will be described with reference to FIGS. 2 to 7. Subsequently, a configuration of a distributed power supply system including a plurality of wind power generation units shown in FIG. 1 will be described with reference to FIGS. 8 and 9, and a distributed power supply power converter is controlled in the distributed power supply system. The control operation for this will be described with reference to FIGS.

  FIG. 1 shows a wind turbine generator unit 1 and a control device 100 according to some embodiments of the present invention. The wind turbine generator unit 1 includes a wind turbine generator 10 and an interconnection circuit section 20. The interconnection circuit unit 20 includes a voltage measuring device 110 for measuring the power generation end voltage of the wind power generator 10, a power converter 120 for connecting the wind power generator 10 to the power system 40, and a transformer 21. Is equipped with. The power converter 120 is electrically coupled to the power system 40 via the transformer 21. Further, the voltage measuring device 110 measures the power generation end voltage of the wind power generator 10 at a grid interconnection point between the wind power generation unit 1 and the power grid 40, and a signal representing the voltage measurement value is described later in AVR. It is supplied to the control unit 150 and the control mode switching unit 210.

The control device 100 shown in FIG. 1 is connected to the power converter 120 via a control line in order to control the output amount of active power and reactive power output from the power converter 120 to the power grid 40. In one exemplary embodiment, the power converter 120 may be configured as a bidirectional inverter, which includes an AC / DC converter section, a DC voltage adjustment section, a DC / AC inverter section, and It may be composed of In the bidirectional inverter, the AC / DC converter unit converts the AC power from the wind power generator 10 into DC, and the DC voltage adjustment unit adjusts the DC voltage from the AC / DC converter unit, and the DC / AC inverter. The unit converts direct current from the DC voltage adjusting unit into alternating current. At that time, according to the voltage control signal input to the bidirectional inverter, the DC voltage output from the DC voltage adjustment unit to the DC / AC inverter unit may be controlled to match the target voltage V _ref . Further, according to the PWM control signal input to the bidirectional inverter, the frequency of the alternating current output from the DC / AC inverter unit to the power system 40 may be controlled to match the target frequency ω _ref .

  On the other hand, the control device 100 according to some embodiments of the present invention is a control device for controlling the power converter 120 for matching the power from the distributed power source including the wind power generator 10 with the power system 40. . Control device 100 includes power control unit 130, limit processing unit 140, AVR control unit 150, MPPT control unit 160, governor control unit 170, adder 190, and control mode switching unit 210 as constituent elements. As described below, when the plurality of wind power generation units 1 are connected to the power system 40, the control device 100 may be provided individually for each of the plurality of wind power generation units 1. In that case, a single central control device may be provided separately from the plurality of wind power generation units 1, and the central control device may be shared by the plurality of wind power generation units 1. In that case, the behaviors of the control devices 100 provided inside the plurality of wind power generation units 1 are collectively controlled by the central control device.

Referring to FIG. 1 again, in the power control unit 130, the output amounts of active power and reactive power output from the power converter 120 to the power grid 40 match the active power command value P _ref and the reactive power command value Q _ref , respectively. The power converter 120 is controlled so that. Specifically, the power control unit 130 outputs from the power converter 120 to the power system 40 so that the output amount of active power and reactive power output from the power converter 120 to the power system 40 becomes a desired output amount. Controls the voltage and frequency of the alternating current that is applied. For example, when the power converter 120 is the above-described bidirectional inverter, the power control unit 130 performs the following power control operation.

  That is, the power control unit 130 gives a voltage control signal from the power control unit 130 to the DC voltage adjustment unit so that the output amount of the reactive power output from the power converter 120 to the power system 40 becomes a desired output amount. , Controls the DC voltage output from the DC voltage adjustment unit to the DC / AC inverter unit. Further, the power control unit 130 outputs a PWM control signal from the power control unit 130 to the DC / AC inverter unit so that the output amount of active power output from the power converter 120 to the power system 40 becomes a desired output amount. The frequency of the alternating current output from the DC / AC inverter unit to the power system 40 is controlled.

  In order to realize the above function, the power control unit 130 controls the power converter 120 so as to adjust the active power supplied from the distributed power source including the wind power generator 10 to the power system 40. And a reactive power control unit 132 for controlling the power converter 120 so as to adjust the reactive power supplied from the distributed power source including the wind power generator 10 to the power system 40.

The active power control unit 131 receives the active power command value P _ref generated by the MPPT control unit 160, the governor control unit 170, and the adder 190 and adjusted by the limit processing unit 140. Then, the active power control unit 131 controls the power converter 120 so that the active power output from the power converter 120 to the power grid 40 matches the active power command value P _ref . The reactive power control unit 132 receives the reactive power command value Q _ref generated by the AVR control unit 150 and adjusted by the limit processing unit 140. Then, the reactive power control unit 132 controls the power converter 120 so that the reactive power output from the power converter 120 to the power grid 40 matches the reactive power command value Q _ref . That is, the power control unit 130, which has received the active power command value P _ref and the reactive power command value Q _ref , outputs the active power command value P _ref and the active power output from the power converter 120 to the power grid 40, respectively. The power converter 120 is controlled so as to match the reactive power command value Q _ref .

  Next, the functions and operations of the AVR control unit 150, MPPT control unit 160, governor control unit 170, and adder 190 will be described in detail. The MPPT control unit 160 receives the wind speed information wd indicating the wind speed from each wind power generation unit 1, and at least controls the wind power generator 10 at the optimum operating point according to the wind speed based on the wind speed information wd. Output a signal. The wind speed information wd may be any information indicating the wind speed acting on each wind power generation unit 1, and for example, the wind speed measurement value measured by the wind speed information sensor 180 provided in each wind power generation unit 1 or The number of revolutions of the wind turbine rotor of the wind power generator 10 measured by the illustrated revolution counter can be used. The MPPT controller 160 may always receive the wind speed information wd from the wind speed information sensor 180. Here, in the MPPT control performed by the MPPT control unit 160, the optimum operating point according to the wind speed is that the wind power generator 10 maximizes the active power output by the wind power generator 10 under a given wind speed. Is the driving point for driving. Therefore, the MPPT control unit 160 can output the first control signal for controlling the wind power generator 10 so that the active power from the wind power generator 10 is maximized based on the wind speed information.

The governor control unit 170 outputs a second control signal for maintaining the grid frequency of the power grid 40 constant. Here, in the governor control performed by the governor control unit 170, the correction amount of the first control signal required to maintain the grid frequency constant is determined in accordance with the fluctuation of the grid frequency of the power grid. 2 Output as a control signal. That is, the governor control unit 170 can output the second control signal for controlling the rotation speed or the torque of the generator so as to maintain the grid frequency constant in response to the fluctuation of the grid frequency of the power grid. is there. Further, the adder 190 determines the first active power command value P1 _ref based on the control signal obtained by adding the first control signal and the second control signal, and outputs the first active power command value P1 _ref to the limit processing unit 140.

As described above, in the configuration of the control device 100 shown in FIG. 1, the first control signal and the system frequency for controlling the wind power generator 10 so that the active power from the wind power generator 10 becomes maximum based on the wind speed information wd. The first active power command value P1 _ref is determined on the basis of the control signal obtained by adding the second control signal for maintaining constant. As a result, in the above configuration, when the first control mode is selected, the power converter 120 is controlled so as to output to the power system 40 the amount of active power that is optimum for stabilizing the system frequency of the power system 40. You can

Further, the AVR control unit 150 determines the second reactive power command value Q2 _ref for maintaining the power generation end voltage of the wind power generator 10 constant, and outputs it to the limit processing unit 140. Therefore, according to the above configuration, when the second control mode m2 is selected, the power converter 120 is configured to output the reactive power of the optimum amount for stabilizing the grid voltage of the power grid 40 to the power grid 40. Can be controlled. Further, in the above configuration, it is desirable that the first reactive power command value Q1 _ref be a value that maintains the system voltage of the power system 40 constant.

  On the other hand, the power generation end voltage of the wind power generator 10 is easier for a power supply supplier to measure than the grid voltage of the power grid 40, and an additional voltage for receiving grid voltage measurement data from the power grid 40 side. No equipment or arrangements are required. Therefore, the AVR control unit 150 controls the reactive power to be output from the power converter 120 to the power system 40 based on the power generation end voltage. When the reactive power is controlled based on the power generation end voltage, the convergence of the system voltage of the power system 40 does not start unless a certain response delay elapses after the power generation end voltage converges to a constant value. Since this response delay is sufficiently small, there is no problem in practical use. Therefore, according to the above configuration, the active power and the reactive power are set to be within the range of the capacity of the power converter 120 based on the power generation end voltage which is easier for the power supply supplier to measure than the system voltage of the power system 40. It is possible to control the amount of electric power output with an accuracy that does not pose a practical problem.

Due to the above-described operation of the limit processing unit 140, the active power command value P _ref and the reactive power command value Q _ref output to the active power control unit 131 and the reactive power control unit 132, respectively, are determined as follows. First, the limit processing unit 140 receives the active power command value P0 _ref generated by the MPPT control unit 160, the governor control unit 170, and the adder 190. Specifically, the active power command value P0 _ref is generated by adding the first control signal output by the MPPT control unit 160 and the second control signal output by the governor control unit 170 by the adder 190, and the limit processing unit is generated. It is output to 140. The limit processing unit 140 also receives the reactive power command value Q0 _ref generated by the AVR control unit 150. Subsequently, the limit processing unit 140 causes the active power command value P0 _ref and the reactive power command value Q0 _{ref to} be given to the power control unit 130 to be equal to or less than a predetermined upper limit value according to the principle described later with reference to FIGS. 3 and 4. Then, the active power command value P0 _ref and the reactive power command value Q0 _ref are adjusted. At that time, the limit processing unit 140 sets the active power command value P0 _ref and the reactive power so that the active power and the reactive power output from the power converter 120 to the power system 40 fall within the range of the capacity of the power converter 120. The power command value Q0 _ref is adjusted so as to be equal to or less than the predetermined upper limit value. In the following description, the active power command value and the reactive power command value before the pre-adjustment by the limit processing unit 140 are expressed as P0 _ref and Q0 _ref , respectively, and after the pre-adjustment by the limit processing unit 140 is performed. The active power command value and the reactive power command value of are referred to as P _ref and Q _ref , respectively.

As described above, in the embodiment shown in FIGS. 1 and 2, the active power command value P0 _ref and the reactive power command value Q0 _ref are adjusted in advance by the limit processing unit 140, and then the active power control unit 131 and the reactive power control unit are controlled. It outputs to each part 132. Accordingly, when the active power command value P _ref and the reactive power command value Q _ref that have not been adjusted in advance by the limit processing unit 140 are output to the active power control unit 131 and the reactive power control unit 132, respectively, The danger can be avoided. That is, as a result of instructing the power converter 120 to output power that exceeds the capacity of the power converter 120 to the power grid 40, there is a risk that the power converter 120 will be overloaded. It can be avoided.

More specifically, limit processing unit 140 performs active power command value Pp _ref and reactive power command in the following manner depending on whether it is operating in first control mode m1 or second control mode m2. The value Qp _ref is modified so as to be equal to or less than the predetermined upper limit value. That is, when the limit processing unit 140 is operating in the first control mode m1, the limit processing unit 140 gives the active power command value P _ref to the active power control unit 131. In this case, as shown in FIG. 2, the active power command value P _ref is the active power command value P 0 _ref output by summing the signals from the MPPT control unit 160 and the governor control unit 170 by the adder 190, which will be described later. It is equal to the value adjusted to be equal to or less than P _rated . At the same time, the limit processing unit 140 operating in the first control mode m1 outputs the maximum reactive power Q that can be output by the power converter 120 when the power converter 120 outputs active power corresponding to the active power command value P _{ref. Find lim} . Then, as shown in FIG. 2, limit processing unit 140 determines reactive power command value Q _ref so as to be equal to or less than maximum reactive power Q _lim , and gives it to reactive power control unit 132. As described above, the first control mode m1 corresponds to power control in which active power is preferentially output to the power grid 40 within the limited capacity of the power converter 120.

On the other hand, when the limit processing unit 140 is operating in the second control mode m2, the limit processing unit 140 gives the reactive power command value Q _ref to the reactive power control unit 132. In this case, as shown in FIG. 2, the reactive power command value Q _ref is equal to a value obtained by adjusting the reactive power command value Q0 _ref output by the AVR control unit 150 so as to be equal to or less than Q _rated described later. At the same time, the limit processing unit 140 operating in the second control mode m2 outputs the maximum active power P that can be output by the power converter 120 when the power converter 120 outputs the reactive power corresponding to the reactive power command value Q _{ref. Find lim} . Then, as shown in FIG. 2, the limit processing unit 140 determines the active power command value P _ref so as to be the maximum active power P _lim or less, and gives it to the active power control unit 131. That is, the second control mode m2 corresponds to power control in which the reactive power is preferentially output to the power grid 40 within the limited capacity of the power converter 120.

Next, a specific method for the limit processing unit 140 to determine the maximum active power P _lim and the maximum reactive power Q _lim described above will be described in more detail with reference to FIG. FIG. 3 shows the relationship between the active power P and the reactive power Q and the capacity of the power converter 120, and the magnitude of the active power P output from the power converter 120 to the power grid 40 corresponds to the horizontal axis. , The reactive power Q output from the power converter 120 to the power grid 40 corresponds to the vertical axis. That is, the coordinate position (p, q) of the two-dimensional coordinates shown in FIG. 3 represents a state in which the active power P and the reactive power Q output from the power converter 120 to the power system 40 are equal to p and q, respectively. .

  In this way, when represented by the coordinate position (p, q) corresponding to the active power P and the reactive power Q output from the power converter 120 to the power system 40, the capacity of the power converter 120 is the circle shown in FIG. It is represented by. Specifically, if the coordinate position (p, q) is located within the circle shown in FIG. 3, the active power P and the reactive power Q output from the power converter 120 to the power grid 40 are the power conversion values. It is within the capacity of the container 120. In other words, the circle shown in FIG. 3 represents the maximum apparent power S that can be output from the power converter 120 to the power system 40, and the effective power P output from the power converter 120 to the power system 40. And the following relationship is established between the reactive power Q and the apparent power S.

ただし、上記の式（１）において、θは電力変換器１２０から電力系統４０に出力される電力の力率を表す。つまり、電力変換器１２０から電力系統４０に出力される有効電力Ｐおよび無効電力Ｑは、電力変換器１２０の容量の範囲内に収まるためには、電力変換器１２０から電力系統４０に最大限出力可能な皮相電力Ｓの大きさをＳ_{ｒａｔｅｄ}とするならば、以下の関係な成り立つ必要がある。

However, in the above formula (1), θ represents the power factor of the power output from the power converter 120 to the power system 40. That is, in order for the active power P and the reactive power Q output from the power converter 120 to the power system 40 to be within the capacity range of the power converter 120, the maximum output from the power converter 120 to the power system 40. If the possible magnitude of the apparent power S is S _rated , the following relations need to hold.

Therefore, based on the relationship shown in FIG. 3 between the active power P and the reactive power Q output from the power converter 120 to the power system 40 and the capacity of the power converter 120, the limit processing unit 140 calculates In this way, the maximum reactive power Q _lim in the first control mode m1 can be calculated. That is, when the control device 100 is operating in the first control mode m1, when the power converter 120 outputs active power corresponding to the active power command value P _ref , the apparent power S in the power converter 120 is the apparent power S of the power converter 120. The maximum reactive power Q _lim is set to a value that matches the capacity. Further, based on the relationship between the active power P and the reactive power Q and the capacity of the power converter 120 shown in FIG. 3, the limit processing unit 140 causes the maximum active power P _lim in the second control mode m2 as follows. To calculate. That is, when the control device 100 is operating in the second control mode m2, the apparent power S in the power converter 120 is the apparent power S of the power converter 120 when the power converter 120 outputs the reactive power corresponding to the reactive power command value Q _ref . The maximum active power P _lim is set to a value that matches the capacity.

Next, the power control when the limit processing unit 140 operating in the first control mode m1 outputs the active power to the power grid 40 with priority over the reactive power in the limited capacity of the power converter 120. A more detailed specific example of the operation will be described with reference to FIG. As will be described below, in the embodiment shown in FIG. 4A, the limit processing unit 140 preferentially transfers active power to the power grid 40 over reactive power in the limited capacity of the power converter 120. The values of the active power command value P0 _ref and the reactive power command value Q0 _ref are adjusted so as to output.

In the first control mode m1, the adder 190 adds the first control signal output by the MPPT control unit 160 and the second control signal output by the governor control unit 170 to generate the active power command value P0 _ref . Then, the active power command value P0 _ref is output from the adder 190 to the limit processing unit 140. Then, the limit processing unit 140 operating in the first control mode m1 determines whether or not the value of the active power command value P0 _ref falls within the numerical range of 0 ≦ P0 _ref ≦ P _rated . Here, P _rated corresponds to the intersection of the rightmost part of the circle shown in FIG. 3 and the horizontal axis, and the maximum output is possible from the power converter 120 when no reactive power is output from the power converter 120. It is the upper limit of effective power. As a result, when P0 _ref > P _rated , the value of the active power command value P0 _ref is adjusted to be equal to P _rated to obtain the active power command value P _ref . Subsequently, the limiting processor 140 outputs the active power control unit 131 the value of the active power command value _{P ref} as a first active power command value _{P ref.}

Subsequently, the limit processing unit 140 outputs the active power to the power system 40 in the limited capacity of the power converter 120, and as a result, the reactive power is supplied within the range of the capacity remaining in the power converter 120. The value of the reactive power command value Q0 _ref is adjusted so that it is output to the grid 40. Specifically, the limit processing unit 140 obtains the maximum reactive power Q _lim that the power converter 120 can output when the power converter 120 outputs active power corresponding to the first active power command value P1 _ref . For example, the limit processing unit 140 has a value at which the apparent power S in the power converter 120 matches the capacity of the power converter 120 when the power converter 120 outputs active power corresponding to the first active power command value P1 _ref. Set the maximum reactive power Q _lim to. In this case, the value of the maximum reactive power Q _lim can be calculated by the following formula.

Then, the limit processing unit 140 determines the first reactive power command value Q _ref by adjusting the reactive power command value Q 0 _ref received from the AVR control unit 150 to be equal to or less than the maximum reactive power Q _lim. . Subsequently, the limit processing unit 140 outputs the reactive power command value Q _ref thus determined to the reactive power control unit 132 as the first reactive power command value Q1 _ref .

On the other hand, in the second control mode m2, the reactive power command value Q0 _ref generated by the AVR control unit 150 is output from the AVR control unit 150 to the limit processing unit 140. Then, the limit processing unit 140 operating in the second control mode m2 determines whether or not the value of the reactive power command value Q0 _ref falls within the numerical range of −Q _rated ≦ Q0 _ref ≦ Q _rated . Here, Q _rated is equal to the apparent power S _rated that can be maximally output from the power converter 120, and corresponds to the intersection of the uppermost part of the circle and the vertical axis shown in FIG. 3. That is, here, Q _rated is the upper limit value of the reactive power that can be output to the maximum from the power converter 120 when the active power is not output from the power converter 120 at all. As a result, when the absolute value of the reactive power command value Q0 _ref (the variation amplitude of the reactive power) becomes larger than S _rated , the reactive power command is set so that the absolute value of the reactive power command value Q0 _ref becomes S _rated or less. The value of the value Q0 _ref is adjusted to be the reactive power command value Q _ref . Subsequently, the limit processing unit 140 outputs the reactive power command value Q _ref to the reactive power control unit 132 as the second reactive power command value Q2 _ref .

Subsequently, the limit processing unit 140 outputs the reactive power to the power system 40 in the limited capacity of the power converter 120, and as a result, the active power is converted into the active power within the range of the capacity remaining in the power converter 120. The value of the active power command value P0 _ref is adjusted so that it is output to the system 40. Specifically, the limit processing unit 140 obtains the maximum active power P _lim that the power converter 120 can output when the power converter 120 outputs the reactive power corresponding to the second reactive power command value Q2 _ref . For example, the limit processing unit 140 sets a value at which the apparent power S in the power converter 120 matches the capacity of the power converter 120 when the power converter 120 outputs the reactive power corresponding to the second reactive power command value Q2 _ref. The maximum active power P _lim is set to. In this case, the value of the maximum active power P _lim can be calculated by the following formula.

Then, the limit processing unit 140 determines the active power command value P _ref by adjusting the active power command value P 0 _ref received from the adder 190 to be equal to or less than the maximum active power P _lim . Subsequently, the limit processing unit 140 outputs the active power command value P _ref thus determined to the active power control unit 131 as the second active power command value P2 _ref .

  Referring again to FIG. 1, the control mode switching unit 210 included in the control device 100 has a role of switching the control mode being executed in the limit processing unit 140 according to the status of the power system. That is, the limit processing unit 140 switches the operation between a plurality of modes including the above-described first control mode m1 and second control mode m2 according to the instruction of the control mode switching unit 210. More specifically, the control mode switching unit 210, based on at least one of the system voltage and the system frequency of the power system 40, the first control mode m1 and the second control mode m1 described above as the control mode being executed by the limit processing unit 140. A mode switching instruction is given to the limit processing unit 140 so as to switch between a plurality of modes including the control mode m2.

  As described above, in both the first control mode m1 and the second control mode m2, the active power and the reactive power output from the power converter 120 to the power system 40 do not become excessive with respect to the capacity of the power converter 120. In addition, active power and reactive power output from the power converter 120 to the power grid 40 can be controlled. Then, the control device 100 switches the control mode between a plurality of modes including the first control mode m1 and the second control mode m2 and executes the control mode according to at least one of the system voltage or the system frequency of the power system 40. can do. In that case, the first control mode m1 is effective in suppressing frequency fluctuations because it corresponds to power control in which active power is preferentially output to the power grid 40 within the limited capacity of the power converter 120. On the other hand, the second control mode m2 is effective in suppressing voltage fluctuation because it corresponds to power control in which reactive power is preferentially output to the power grid 40 within the limited capacity of the power converter 120. Therefore, according to the above configuration, the power converter 120 outputs to the power system 40 so as to suppress the frequency fluctuation and the voltage fluctuation in the power system 40 as much as possible within the limited capacity range of the power converter 120. It is possible to properly control the active power and the reactive power that are generated.

  Next, with reference to FIGS. 5 to 7, detailed embodiments regarding switching of control modes by the control mode switching unit 210 and operations of the limit processing unit 140 in the first control mode m1 and the second control mode m2 will be described. To do. As a premise for describing such an embodiment, a grid interconnection rule may be set for the power grid 40 that is interconnected with the power generation system as shown in FIG. 1. In the system interconnection regulation, the maximum range in which the voltage deviation from the rated voltage is allowed due to the voltage fluctuation and the maximum range in which the frequency deviation from the rated frequency is allowed due to the frequency fluctuation are defined as. In this case, if the system voltage of the power system 40 is within the first specified range, the voltage fluctuation is acceptable, and if the system frequency of the power system is within the second specified range, the frequency fluctuation is acceptable.

  Therefore, in an exemplary embodiment, in the control device 100, the control mode switching unit 210 determines whether the grid voltage of the power grid 40 is within the first specified range or the grid frequency of the power grid 40 is the second specified range. It is configured to switch the above-mentioned control mode depending on whether or not it is within the range. Therefore, according to this embodiment, depending on whether the frequency variation or the voltage variation in the power system 40 is unacceptable, within the limited capacity of the power converter 120, the unacceptable variation. The active power and the reactive power output from the power converter 120 to the power system 40 can be controlled so as to suppress the power consumption. As described above, according to this embodiment, in order to suppress the frequency fluctuations and the voltage fluctuations in the power system 40 depending on the cause of the system disturbance, the electric power is reduced within the limited capacity of the power converter 120. The active power and the reactive power output from the converter 120 to the power system 40 can be controlled more appropriately.

  Further, in an exemplary embodiment, the control mode switching unit 210 operates the control device 100 in the second control mode m2 when the system voltage deviates from the first specified range, and the system frequency becomes the second specified range. When deviating from the above, the control device 100 is configured to operate in the first control mode m1. As a result, according to this embodiment, of the voltage fluctuation and the frequency fluctuation of the electric power system 40, when the voltage fluctuation deviates from the allowable range, the control mode switching unit 210 switches to the first control mode m1 and the frequency fluctuation. Is deviated from the allowable range, it is possible to switch to the second control mode m2.

Next, the flow from the control mode switching operation by the control mode switching unit 210 to the power command value determination operation by the limit processing unit 140 according to the switched control mode will be described with reference to FIGS. 5 to 7. . FIG. 5 shows an example of a specific method for the control mode switching unit 210 to determine whether or not the voltage fluctuation in the power system 40 has deviated from the allowable range. 5, the control mode switching unit 210 monitors over a period of T seconds the generator end voltage of the wind power generator 10 from the time t _p to the present time, measured at a plurality of time included in the period of T seconds The standard deviation V _sd is calculated for the instantaneous value of the generated power generation end voltage. The standard deviation V _sd is calculated on the assumption that the rated voltage defined by the grid interconnection regulation of the power system 40 matches the average value of the power generation end voltage, and the power generation of the wind power generator 10 in the period of T seconds shown in FIG. It represents the magnitude of the fluctuation range of the end voltage. Therefore, if the voltage fluctuation according to the value of the standard deviation V _sd deviates from the predetermined allowable range, the fluctuation of the system voltage is approximated by the fluctuation of the power generation end voltage, so that the system voltage within the power system 40 1 There is no problem in practical use even if it is judged that it has deviated from the specified range. This is because a certain response delay has to elapse before the fluctuation of the power generation end voltage is reflected in the fluctuation of the system voltage of the power system 40, but this response delay is so small that it does not pose a practical problem. is there.

A specific method for the control mode switching unit 210 to determine whether or not the frequency fluctuation in the power system 40 has deviated from the permissible range can also be realized according to the same concept as that of the embodiment shown in FIG. it can. That is, the control mode switching unit 210 monitors the grid frequency of the power grid 40 over a predetermined period from the past to the present time, and calculates the standard deviation ω _sd of the instantaneous voltage measured at a plurality of times in the predetermined period. This standard deviation ω _sd is calculated on the assumption that the rated frequency defined in the grid interconnection regulation of the power system 40 matches the average value of the grid frequencies, and represents the magnitude of the fluctuation range of the grid frequencies in the above-mentioned predetermined period. . Therefore, if the frequency variation according to the value of the standard deviation ω _sd deviates from the predetermined allowable range, it can be determined that the system frequency in the power system 40 deviates from the second specified range.

In FIG. 6, when the system voltage deviates from the first specified range, the limit processing unit 140 is operated in the second control mode m2. In other cases, the limit processing unit 140 is operated in the first control mode m1. It is a flow chart which shows the flow of the operation when operating. The flowchart of FIG. 6 starts from step S501, and the control mode switching unit 210 measures the instantaneous value of the power generation end voltage of the wind power generator 10 at a plurality of times included in the period of T seconds shown in FIG. The standard deviation V _sd is calculated for the instantaneous value of the power generation end voltage of. Subsequently, the process proceeds to step S502, and the control mode switching unit 210 determines whether the standard deviation V _sd is less than or equal to a predetermined threshold V _{sd_ref} . If V _{sd ≤V sd_ref} in step S502, it is considered that the system voltage is within the first specified range, the process proceeds to step S503, and the limit processing unit 140 is started to operate in the first control mode m1. On the contrary, if V _sd > V _{sd_ref} in step S502, it is considered that the system voltage has deviated from the first specified range, the process proceeds to step S506, and the limit processing unit 140 is started to operate in the second control mode m2. .

続いて、リミット処理部１４０は、第１有効電力指令値Ｐ１_ｒｅｆの値を有効電力指令値Ｐ_ｒｅｆとして有効電力制御部１３１に出力する。 In step S504, the limit processing unit 140 operating in the first control mode m1 determines whether the value of the first active power command value P1 _ref received from the adder 190 falls within the numerical range of 0 ≦ P1 _ref ≦ P _rated . Determine whether or not. As a result, when P1 _ref > P _rated , the value of the first active power command value P1 _ref is corrected so that P1 _ref = P _rated . That is, the limit processing unit 140 determines the active power command value P _ref output to the active power control unit 131 from the first active power command value P1 _ref according to the following formula.

Then, the limit processing unit 140 outputs the value of the first active power command value P1 _{ref to} the active power control unit 131 as the active power command value P _ref .

Subsequently, the execution of the flowchart in FIG. 6 proceeds to step S504. In step S504, the limit processing unit 140 causes the apparent power S in the power converter 120 to match the capacity of the power converter 120 when the power converter 120 outputs active power corresponding to the first active power command value P1 _ref. The maximum reactive power Q _lim is set to the value to be set. In this case, the value of the maximum reactive power Q _lim can be calculated by the following formula.

Then, the execution of the flowchart of FIG. 6 proceeds to step S505. In step S505, the limit processing unit 140 determines the first reactive power command value Q1 _ref by adjusting the reactive power command value Q _ref received from the AVR control unit 150 to be equal to or less than the maximum reactive power Q _lim. . Then, the limit processing unit 140 outputs the first reactive power command value Q1 _ref thus determined to the reactive power control unit 132 as the reactive power command value Q _ref . That is, the limit processing unit 140 determines the first reactive power command value Q1 _ref to be output to the reactive power control unit 132 from the maximum reactive power Q _lim according to the following formula.

続いて、リミット処理部１４０は、第２無効電力指令値Ｑ２_ｒｅｆを上記のように調整した値を無効電力指令値Ｑ_ｒｅｆとして無効電力制御部１３２に出力する。 On the other hand, when execution of the flowchart of FIG. 6 proceeds from step S502 to step S506, the limit processing unit 140 that has started operation in the second control mode m2 sets the reactive power command value Q _ref generated by the AVR control unit 150 to AVR. Received as the second reactive power command value Q2 _ref from the control unit 150. Then, the limit processing unit 140 determines whether or not the value of the second reactive power command value Q2 _ref falls within the numerical range of −Q _rated ≦ Q2 _ref ≦ Q _rated . As a result, when the absolute value of the second reactive power command value Q2 _ref (the fluctuation amplitude of the reactive power) becomes larger than S _rated , the absolute value of the second reactive power command value Q2 _ref becomes equal to or lower than S _rated. Then, the value of the second reactive power command value Q2 _ref is corrected. That is, the limit processing unit 140 determines the reactive power command value Q _ref output to the reactive power control unit 132 from the second reactive power command value Q2 _ref according to the following formula.

Subsequently, the limit processing unit 140 outputs the value obtained by adjusting the second reactive power command value Q2 _ref as described above to the reactive power control unit 132 as the reactive power command value Q _ref .

Then, the execution of the flowchart of FIG. 6 proceeds to step S507. In step S507, the limit processing unit 140 causes the apparent power S in the power converter 120 to match the capacity of the power converter 120 when the power converter 120 outputs the reactive power corresponding to the second reactive power command value Q2 _ref. The maximum active power P _lim is set to the value to be set. In this case, the value of the maximum active power P _lim can be calculated by the following formula.

Then, the execution of the flowchart of FIG. 6 proceeds to step S507. In step S507, the limit processing unit 140 determines the second active power command value P2 _ref by adjusting the active power command value P _ref received from the adder 190 to be equal to or less than the maximum active power P _lim . Subsequently, the limit processing unit 140 outputs the second active power command value P2 _ref thus determined to the active power control unit 131 as the active power command value P _ref . The limit processing unit 140 determines the second active power command value P2 _ref output to the active power control unit 131 from the maximum active power P _lim according to the following formula.

In FIG. 7, when the system frequency deviates from the second specified range, the limit processing unit 140 is operated in the first control mode m2, and in other cases, the limit processing unit 140 is operated in the second control mode m2. It is a flow chart which shows a flow of operation in a case. The flowchart of FIG. 7 starts from step S601, and the control mode switching unit 210 measures the instantaneous values of the system frequency at a plurality of times included in the period of T seconds shown in FIG. Calculate f _sd . Subsequently, the process proceeds to step S602, and the control mode switching unit 210 determines whether the standard deviation f _sd is less than or equal to a predetermined threshold value f _{sd_ref} . If f _{sd ≤f sd_ref} in step S602, it is considered that the system frequency is within the second specified range, the process proceeds to step S603, and the limit processing unit 140 is started to operate in the second control mode m2. On the contrary, if f _sd > f _{sd_ref} in step S602, it is considered that the system frequency has deviated from the second specified range, the process proceeds to step S606, and the limit processing unit 140 starts operating in the first control mode m1. .

  Subsequently, when the execution of the flowchart of FIG. 7 proceeds to step S603, the limit processing unit 140 performs the same processing as steps S506 to S508 of FIG. 6 in order to determine the power command value under the second control mode m2. Perform an action. On the other hand, when the execution of the flowchart of FIG. 7 proceeds to step S606, the limit processing unit 140 performs the same processing operation as steps S503 to S505 of FIG. 6 in order to determine the power command value under the first control mode m1. To execute.

  By the way, in the embodiment described above with reference to FIG. 6 and FIG. 7, the control mode switching unit 210 monitors only one of the system voltage and the system frequency as the state of the power system 40, and one of them is within the allowable range. The control mode is switched according to whether or not there is a deviation. On the other hand, in the embodiment described later with reference to FIG. 8, the control mode switching unit 210 may monitor both the system voltage and the system frequency at the same time, and both the system voltage and the system frequency may deviate from the allowable range at the same time. The control mode is switched taking this into consideration. As a result, in the embodiment shown in FIG. 8, even when the system voltage V deviates from the first specified range and the system frequency f deviates from the second specified range, it is appropriate according to the situation. It becomes possible to switch to the control mode.

Hereinafter, the flow of the operation in which the control mode switching unit 210 switches the control mode while simultaneously considering both the system voltage fluctuation and the system frequency fluctuation will be described with reference to the flowchart of FIG. The flowchart of FIG. 8 starts from step S701, and the control mode switching unit 210 calculates the standard deviation f _sd of the system frequency corresponding to the fluctuation range of the system frequency by the same method as in step S601 shown in FIG. Subsequently, the process proceeds to step S702, and the control mode switching unit 210 calculates the standard deviation V _sd of the power generation end voltage that approximates the fluctuation range of the system voltage by the same method as in step S501 shown in FIG.

Subsequently, the control mode switching unit 210 compares the standard deviation V _sd with a predetermined threshold V _{sd_ref} , as in step S502 shown in FIG. Further, the control mode switching unit 210 compares the standard deviation f _sd with a predetermined threshold value f _{sd_ref} as in step S602 shown in FIG. 7. Then, the control mode switching unit 210 switches the control mode between the first control mode m1 and the second control mode m2 according to the result of the above-described comparison. For example, if the control mode switching unit 210 determines in step S703 that V _{sd ≤V sd_ref} and f _{sd ≤f sd_ref} , both the system voltage and the system frequency fall within the allowable range. Therefore, the control mode switching unit 210 may switch the control mode to either the first control mode m1 or the second control mode m2 (step S704 in FIG. 8).

If the control mode switching unit 210 determines in step S705 that V _sd > V _{sd_ref} and f _sd ≦ f _{sd_ref} , only the system voltage falls _{outside the} allowable range. 210 switches the control mode to the second control mode m2 (step S706 in FIG. 8). If the control mode switching unit 210 determines in step S707 that V _{sd ≤V sd_ref} and f _sd > f _{sd_ref} , only the system frequency falls _{outside the} allowable range. 210 switches the control mode to the first control mode m1 (step S708 in FIG. 8).

When the control mode switching unit 210 determines that V _sd > V _{sd_ref} and f _sd > f _{sd_ref} as a result of the above-described comparison, the process proceeds to step S709, and the system voltage V is in the first specified range. And the system frequency f deviates from the second specified range. Specifically, in S709, the ratio of the deviation amount from the first specified range to the size of the first specified range for the system voltage V is calculated as the deviation ratio V _{sd_pu} of the system voltage V. Further, in S709, the ratio of the deviation amount from the second specified range to the size of the second specified range for the system frequency f is calculated as the deviation ratio f _{sd_pu} of the system frequency f.

Subsequently, the process proceeds to step S710, the control mode switching unit 210 compares the deviation ratio _{f Sd_pu} deviation ratio _{V Sd_pu} and system frequency f of the system voltage _V, and whether the _{V sd_pu>} V sd_pu judge. _And if the _{V sd_p>} V sd_p, control mode switching unit 210 switches the control mode to the second control mode m2 (step S711 in FIG. _8), if the _{V sd_pu} ≦ _{V sd_pu,} control mode switching unit 210 switches the control mode to the first control mode m1 (step S712 in FIG. 8).

That is, in steps S709 to S712 shown in FIG. 8, the ratio of the deviation amount from the specified range to the size of the specified range (first specified range or second specified range) is deviated for each of the system voltage V and the system frequency f. If it is a ratio, the control mode is switched as follows. That is, the control mode switching unit 210, based on the deviation ratio _{f Sd_pu} magnitude of the second prescribed range of the deviation ratio _{V Sd_pu} and system frequency f from the first defined range of the system voltage V, the first control mode m1 And one of the second control modes m2 is selected.

  In the embodiment described above with reference to FIG. 8, when both the voltage fluctuation and the frequency fluctuation of the electric power system 40 are not acceptable, the system voltage V and the system voltage are set to the extent of deviation from the allowable range defined by the system interconnection regulation. Either the first control mode m1 or the second control mode m2 can be selected depending on which of the frequencies f is significant. That is, depending on which of the system voltage V and the system frequency f is significant in the degree of deviation from the allowable range defined by the system interconnection regulation, the active power and the reactive power are limited within the limited capacity of the power converter 120. It is possible to select which of these is preferentially output to the power system 40. As described above, according to the above configuration, the power conversion is performed within the limited capacity of the power converter 120 so as to suppress the frequency fluctuation and the voltage fluctuation in the power system 40, whichever is more affected. The active power and the reactive power output from the device 120 to the power system 40 can be controlled more appropriately.

Further, in the embodiment shown in FIG. 8, it is determined that the system voltage V deviates from the first specified range and the system frequency f deviates from the second specified range, so that the process is step S709. When proceeding to step S <b> 710, the following processing procedure may be executed instead of steps S <b> 710 to S <b> 712 shown in FIG. 8. That is, the control mode switching unit 210 first determines the ratio V _{sd_pu} determined based on the deviation ratio V _{sd_pu} of the system voltage V from the first specified range and the deviation ratio f _{sd_pu} of the system frequency from the second specified range. Calculate / f _{sd_pu} . Subsequently, the control mode switching unit 210 proportionally _divides the capacity of the power converter 120 into a first capacity for active power and a second capacity for reactive power according to the ratio V _{sd_pu} / f _{sd_pu} , and determines the active power as the first value. It is limited within the range of one capacity, and the reactive power is limited within the range of the second capacity.

That is, in this embodiment, the deviation ratios V _{sd_pu} and f _{sd_pu} from the allowable range defined by the grid interconnection regulation for the voltage fluctuations and the frequency fluctuations of the power system 40 are evaluated, and the voltage fluctuations and the frequency fluctuations are respectively evaluated. The relative ratio V _{sd_pu} / f _{sd_pu} of the deviation ratio is obtained. Moreover, in the above configuration, the relative ratio between the output amount of active power and the output amount of reactive power that can be output to the power system 40 from the power converter 120 to the maximum is the relative ratio V _{sd_pu} / f of the deviation ratio described above. It is set according to _{sd_pu} . From the above, according to the above configuration, when both the voltage fluctuation and the frequency fluctuation of the power system 40 deviate from the allowable range determined by the system interconnection regulation, the power converter 120 changes the power system 40 as follows. It is possible to control the output amount of active power and reactive power output to the. That is, according to the above configuration, the active power and the reactive power for respectively suppressing the voltage fluctuation and the frequency fluctuation as much as possible according to the contribution rate of the voltage fluctuation and the frequency fluctuation contributing to the system disturbance of the power system 40. The output amount can be controlled appropriately.

  Next, referring to FIGS. 9 to 13, a control device 200 for controlling a power converter for a distributed power source will be described according to still another embodiment of the present invention. The distributed power source according to the embodiment shown in FIGS. 9 to 13 includes a plurality of wind power generation units 1 (1a to 1N) each including a wind power generator 10 (10a to 10N) and a power converter 120 (120a to 120N). Including (N units). The configuration of each wind power generation unit 1 (1a to 1N) is the same as the configuration shown in FIG. 1 except that it cooperates with the control device 200 shown in FIGS. 9 and 10. In one example, the distributed power source according to the embodiment illustrated in FIGS. 9 to 13 is a wind farm including a plurality of wind power generation units 1 (1 a to 1 N) installed at a plurality of different locations in a predetermined geographical area. May be In that case, the wind speed observed in each of the plurality of wind power generation units 1 (1a to 1N) differs depending on the distribution of the wind speed in the wind farm. Therefore, in the embodiment shown in FIGS. 9 to 13, the control mode of each wind power generation unit 1 (1a to 1N) is switched in consideration of the difference in wind speed among the plurality of wind power generation units 1a to 1N. You may

  Referring to FIG. 9, the control device 100 (100a to 100N) may be individually provided for each of the plurality of wind power generation units 1 (1a to 1N). In that case, a single central control device 200 is provided separately from the plurality of wind power generation units 1 (1a to 1N), and the central control device 200 is shared by the plurality of wind power generation units 1 (1a to 1N). You may In that case, the behavior of the control devices 100 (100a to 100N) provided inside the plurality of wind power generation units 1 (1a to 1N) is collectively controlled by the central control device 200.

  The central control device 200 receives various measurement signals from the wind turbine generator units 1 (1a to 1N) via the control signal line CL. For example, the wind speed information measured by the wind speed information sensor 180 (see FIG. 1) included in each wind power generation unit 1 (1a to 1N) is transmitted from each wind power generation unit 1 (1a to 1N), and the central control is performed. Received by device 200. Thereby, the central control device 200 can grasp the difference in the wind speed among the plurality of wind power generation units 1a to 1N. Further, the central control device 200 transmits a command signal via the control signal line CL to the control devices 100 (100a to 100N) individually provided in each of the wind power generation units 1 (1a to 1N). For example, the central control device 200 transmits a command signal that defines the behavior pattern of each wind power generation unit 1 (1a to 1N) to the control devices 100a to 100N included in each of the plurality of wind power generation units 1a to 1N. You may

  The power converters 120a to 120N included in the plurality of wind power generation units 1a to 1N are connected to the transformer 300 via the power line PL1 and further connected to the power system 40 via the transformer 300. The control device 200 is also configured to measure the system voltage and the system frequency from the power line PL1 via the measurement line PL2.

  FIG. 10 shows a power curve unique to each wind power generation unit 1 (1a to 1N), and changes in active power that each of the wind power generation unit 1 (1a to 1N) can output according to the wind speed. Represents In the power curve shown in FIG. 10, the horizontal axis corresponds to the wind speed, and the vertical axis corresponds to the active power that can be output from each wind power generation unit 1 (1a to 1N) according to the wind speed. In the power curve shown in FIG. 10, a specific threshold value θ is set on the horizontal axis, and the threshold value θ can be adjusted by the unit classification unit 240. Further, in the power curve shown in FIG. 10, the region 52 in which the wind speed is higher than the threshold value θ corresponds to the operation region (high wind speed region) in which the wind energy received by the wind power generation unit 1 (1a to 1N) is relatively large. The region 51 where the wind speed is smaller than the threshold value θ corresponds to an operating region (low wind speed region) in which the wind energy received by the wind power generation unit 1 (1a to 1N) is relatively small.

  Therefore, the central control device 200 determines whether the wind power generation unit 1 is operating in the operating region 52 or the operating region 51 (that is, whether the operating point of the wind power generator is in the operating region 52 or the operating region 51). The wind power generation unit 1 is classified into a first unit U1 and a second unit U2 as follows according to whether or not there is. The first unit U1 controls the power converters 120 (120a to 120N) in the first control mode m1 as the main control mode when the grid voltage is stable, and the second unit U2 as the sub-control mode when the grid voltage is unstable. The power converter 120 (120a to 120N) is controlled in the control mode m2. The second unit U2 controls the power converters 120 (120a to 120N) in the second control mode m2 as the main control mode when the grid frequency is stable, while it controls the power converter 120 (120a to 120N) as the sub-control mode when the grid frequency is unstable. The power converter 120 (120a to 120N) is controlled in the first control mode m1.

  Subsequently, an internal configuration of the central control device 200 will be described with reference to FIG. 11 shows a part of the configuration of the control device 100 (100a to 100N) shown in FIG. 9 in addition to the internal configuration of the control device 200. The central controller 200 further includes a system state calculation unit 230, an allocation number determination unit 220, and a unit classification unit 240, which will be described later. Further, in the device configuration shown in FIG. 11, the control mode switching unit 210 (210a to 210N), the limit processing unit 140 (140a to 140N), and the power control unit 130 (130a to 130N) are the control device 100 (100a to 100N). Is part of. The control device 100 (100a to 100N) is provided individually for each of the plurality (N units) of wind power generation units 1a to 1N. Here, the power control unit 130 (130a to 130N) controls the power command value that commands the power to be output to the power grid 40 to the power converters 120a to 120N included in the wind power generation units 1a to 1N, respectively. It is transmitted via the signal line CL (FIG. 8).

The system state calculation unit 230 is configured to calculate the system voltage deviation ratio V _{sd_pu} and the system frequency deviation ratio f _{sd_pu} . The unit classification unit 240 includes a plurality of wind power generation units 1a to 1N, at least one or more first units U1, and one or more second units U2 other than the first unit U1 and having a lower wind speed than the first unit U1. It is configured to be classified into ,. Further, the allocation number determination unit 220 determines whether the deviation ratio V _{sd_pu} of the system voltage from the first specified range and the deviation ratio f _{sd_pu} of the system frequency from the second specified range are large or small. It is configured to adjust the unit allocation number and the unit allocation number of the second unit U2. Further, as will be described later with reference to FIG. 11, the allocation number determination unit 220 is configured to include provisional number determination units 221, 222 and a unit allocation number adjustment unit 223.

  In the control device 200 shown in FIG. 11, the unit classification unit 240 receives wind speed information from each of the plurality of wind power generation units 1a to 1N. The unit classification unit 240 also receives the unit allocation number of the first unit U1 and the unit allocation number of the second unit U2 from the allocation number determination unit 220. Then, the unit classification unit 240 classifies the plurality of wind power generation units 1a to 1N into the first unit U1 and the second unit U2 based on the received wind speed information to generate a classification result. At that time, the unit classification unit 240 classifies the units such that the number of the first units U1 becomes equal to the unit allocation number of the first unit U1 received from the allocation number determination unit 220. Similarly, the unit classification unit 240 classifies the units such that the number of the second units U2 becomes equal to the unit allocation number of the second unit U2 received from the allocation number determination unit 220.

  Subsequently, the control mode switching unit 210 (210a to 210N) that has received the classification result from the unit classification unit 240 performs the following control mode switching for each of the limit processing units 140a to 140N according to the classification result. Perform an action. First, for the first unit U1, while the system voltage V of the power system 40 is within the first specified range, the power converter 120 (120a to 120N) is controlled in the first control mode m1 as the main control mode. Then, when the system voltage V deviates from the first specified range, the power converter 120 (120a to 120N) is controlled in the second control mode m2 as the sub control mode. Further, for the second unit U2, when the system frequency f of the power system 40 is within the second specified range, the power converter 120 (120a to 120N) is controlled in the second control mode m2 as the main control mode. Then, when the system frequency f deviates from the second specified range, the power converter 120 (120a to 120N) is controlled in the first control mode m1 as the sub-control mode.

  Next, a specific method in which the unit classification unit 240 classifies the plurality of wind power generation units 1 (1a to 1N) into the first unit U1 and the second unit U2 will be described with reference to FIG. 10. The unit classification unit 240 classifies the wind power generation unit 1 that is operating in the operating region 52 (that is, the operating point of the wind power generator is in the operating region 52) into the first unit U1. On the contrary, the unit classification | category part 240 classifies the wind power generation unit 1 which is driving in the operation area 51 (namely, the operating point of a wind power generator exists in the operation area 51) into the 2nd unit U2. At that time, the unit classification unit 240 adjusts the threshold value θ of the wind speed corresponding to the boundary position between the operation region 51 and the operation region 52 to classify into the number of units classified into the first unit U1 and the second unit U2. Adjust the number of units and. Specifically, the unit classification unit 240 adjusts the value of the threshold θ according to the unit allocation number received from the allocation number determination unit 220 as follows. That is, in the unit classification unit 240, the number of units classified into the first unit U1 becomes equal to the unit allocation number of the first unit U1 received from the allocation number determination unit 220, and the number of units classified into the second unit U1. Adjusts the value of the threshold value θ to be equal to the unit allocation number of the second unit U2 received from the allocation number determining unit 220.

  Next, with reference to FIG. 12 and FIG. 13, a process executed in the control device 200 for classifying each of the plurality of wind power generation units 1 (1a to 1N) into the first unit U1 and the second unit U2. The procedure will be described. The flowchart of FIG. 11 illustrates a system state calculation unit 230 and an allocation number determination unit 220 for classifying each of the plurality of wind power generation units 1 (1a to 1N) into a first unit U1 and a second unit U2 in the control device 200. 3 shows a flow of processing executed by the unit classification unit 240.

The flowchart of FIG. 12 starts from step S1101, and the grid state calculation unit 230 that has received the grid frequency f obtains the standard deviation f _sd of the grid frequency f in the same manner as step S601 of FIG. Similar to S709, the deviation ratio f _{sd_pu} of the system frequency f from the second specified range is calculated. Subsequently, the process proceeds to step S1102, and the system state calculation unit 230 that has received the system voltage V obtains the standard deviation V _sd of the system voltage V in the same manner as step S501 of FIG. 6, and at the same time as step S709 of FIG. Similarly, the deviation ratio V _{sd_pu} of the system voltage V from the first specified range is obtained.

Then, processing proceeds to a step S1103, the provisional number determination unit 221 of the allocation number determining unit 220, the provisional number _{N 1_Org} of the first unit U1 in response to the deviation ratio _{f Sd_pu} from the first specified range of system frequency f To decide. Further, tentative number determining unit 222 of the allocation number determining section 220 determines the provisional volume _N 2 _Org of the second unit U2 according to deviation ratio _{V Sd_pu} from the second prescribed range of the system voltage V. At that time, the provisional number determination unit 221 of the allocation number determining unit 220 calculates the provisional number _{N 1_Org} of the first unit U1 from the deviation ratio _{f Sd_pu} based on the relationship shown in FIG. 13 (A). Further, tentative number determining unit 222 of the allocation number determining unit 220 calculates the provisional number _{N 2_Org} of the second unit U2 from the deviation ratio _{V Sd_pu} based on the relationship shown in FIG. 13 (B).

Subsequently, the process proceeds to step S1104, and the unit allocation number adjustment unit 223 in the allocation number determination unit 220 determines that the total of the provisional number _{N1_org} of the first unit U1 and the provisional number _{N2_org} of the second unit U2 is the wind power generation unit. It is determined whether or not the total number of 1 (1a to 1N) (N units) or less. _If the total of the provisional number _{N1_org} of the first unit U1 and the provisional number _{N2_org} of the second unit U2 is N or less, the process of the unit allocation number adjusting unit 223 proceeds to step S1108, and if it is larger than N, the process is performed. Advances to step S1105. In step S1105, the unit allocation number adjustment unit 223 determines whether or not the deviation ratio V _{sd_pu} of the system voltage V from the second specified range is larger than the deviation ratio f _{sd_pu} of the system frequency f from the first specified range.

When the deviation ratio V _{sd_pu} is larger than the deviation ratio f _{sd_pu} , the process of the unit allocation number adjusting unit 223 proceeds to step S1106, and the unit allocation number adjusting unit 223 sets the provisional number N 2 _—org of the second unit U2 to the second unit U2. Set to the unit allocation number. In addition, the unit allocation number adjustment unit 223 sets the number obtained by subtracting the provisional number _{N2_org} of the second unit U2 from the total number (N units) of the wind power generation units 1 (1a to 1N) as the unit allocation number of the first unit U1. To do. On the contrary, when the deviation ratio V _{sd_pu} is less than or equal to the deviation ratio f _{sd_pu} , the process of the unit allocation number adjusting unit 223 proceeds to step S1107, and the unit allocation number adjusting unit 223 sets the provisional number N _{1_org} of the first unit U1 to the first Set to the unit allocation number of 1 unit U1. In addition, the unit allocation number adjustment unit 223 sets the number obtained by subtracting the provisional number _{N1_org} of the first unit U1 from the total number (N units) of the wind power generation units 1 (1a to 1N) as the unit allocation number of the second unit U2. To do.

On the other hand, when the process proceeds from step S1104 to step S1108, the unit allocation number adjustment unit 223 sets the provisional number _{N2_org} of the second unit U2 to the unit allocation number of the second unit U2, and the wind power generation unit 1 (1a ~ 1N) (N units) minus the provisional number _{N2_org} of the second unit U2 is set as the unit allocation number of the first unit U1.

  When the number of unit allocations of the first unit U1 and the number of unit allocations of the second unit U2 are determined by the number-of-allocations determining unit 220 as described above, the process proceeds to step S1109 and the number of unit allocations of the first unit U1 is determined. The unit allocation number of the second unit U2 is output to the unit classification unit 240. In step S1109, the unit classification unit 240 makes the number of units classified into the first unit U1 equal to the unit allocation number of the first unit U1 received from the allocation number determination unit 220, and classifies into the second unit U1. The value of the threshold value θ shown in FIG. 10 is adjusted so that the number of units becomes equal to the unit allocation number of the second unit U2 received from the allocation number determination unit 220. Then, the unit classification unit 240 classifies the wind power generation unit 1 that is operating in the operation region 52 of FIG. 10 (that is, the operating point of the wind power generator is in the operation region 52) into the first unit U1. . Conversely, the unit classification unit 240 classifies the wind power generation unit 1 that is operating in the operating region 51 of FIG. 10 (that is, the operating point of the wind power generator is in the operating region 51) into the second unit U2.

  As described above, in the embodiment shown in FIGS. 1 to 8, even when the distributed power sources are configured by a plurality (N) of wind power generation units 1 (1a to 1N), the grid of the power grid 40 is provided. Uniform control mode switching is performed in all the wind power generation units 1a to 1N depending on whether or not at least one of the voltage V and the grid frequency f is unstable. For example, if the grid frequency f is unstable, all the wind turbine generator units 1a to 1N are switched to the first control mode m1, and if the grid voltage V is unstable, all the wind turbine generator units 1a to 1N are switched to the second control mode m2. Something like switching happens.

  However, when the wind speeds of the plurality of wind power generation units 1a to 1N are different, since the rotation speed and the output of the generator can be maintained high in the wind power generation unit having a high wind speed, the output of active power from such a wind power generation unit. Competence should be prioritized over reactive power and actively increased. Therefore, in the embodiment shown in FIGS. 9 to 13, for the first unit U1 having a relatively high wind speed, the first control mode m1 is set as the main control mode, and active power is preferentially output when the grid voltage is stable. I have to. On the contrary, in the second unit U2 having a relatively low wind speed, since the rotation speed of the generator is low and the wind energy that can be extracted as the power generation output is scarce, it is not possible to expect to obtain a large amount of active power from the second unit U2. Therefore, in the embodiment shown in FIGS. 9 to 13, for the second unit U2, the second control mode m2 is set as the main control mode in preparation for a voltage fluctuation of the power system 40, and is disabled when the system frequency is stable. Power is output preferentially.

  As described above, according to the embodiment shown in FIGS. 9 to 13, the output control of the electric power is performed within the range of the capacity of the electric power converter 120 for each wind power generation unit 1, and the wind speed distribution according to the wind speed distribution in the distributed power source is performed. Thus, as much active power as possible can be extracted from the unit set including the first unit U1 having a relatively high wind speed. Further, according to the embodiments shown in FIGS. 9 to 13, since it is not possible to expect a large amount of active power to be obtained from the unit set including the second unit U2 having a relatively low wind speed, the system voltage is stabilized. It is possible to positively output the reactive power.

The first unit U1 that preferentially outputs active power when the grid is stable contributes to frequency stabilization of the power grid 40, and the second unit U2 that preferentially outputs reactive power when the grid is stable is the power grid 40. Contributes to the voltage stabilization of. Therefore, in the embodiment shown in FIGS. 9 to 13, the provisional numbers N 1 — _org and N 2 — _org of the first unit U1 and the second unit U2 are determined according to the degree of abnormality of the system voltage V and the system frequency f, respectively. All the remaining numbers of wind power generation units except the provisional number N 2 — _org of 2 units are set to the unit allocation number of the first unit. As a result, according to the embodiment shown in FIGS. 9 to 13, by allocating as many units as possible to the first unit U1 that preferentially outputs active power in the main control mode, as many as possible. It is possible to secure the required number of the second units U2 while supplying the effective power of the above to the power system 40.

  Further, in the embodiment shown in FIGS. 9 to 13, the first unit U1 and the second unit U1 are selected depending on whether the system voltage or the system frequency is significant in the degree of deviation from the allowable range defined by the system interconnection regulation. The unit allocation number of U2 is determined as follows. That is, if the deviation of the system frequency f is greater, the number of unit allocations of the first unit U1 that contributes to frequency stabilization of the power system 40 among the total number (N units) of the plurality of wind power generation units 1a to 1N. Is preferentially secured, and the number of remaining wind power generation units is set as the unit allocation number of the second unit U2. On the contrary, if the deviation of the system voltage V is larger, the unit allocation of the second unit U2, which contributes to the voltage stabilization of the power system 40, out of the total number (N units) of the plurality of wind power generation units 1a to 1N. The number of remaining wind power generation units is set as the unit allocation number of the first unit U1. From the above, according to 1a to 1N, the number of unit allocations of the first unit U1 and the unit of the second unit U2 are controlled so as to suppress the fluctuation of the frequency fluctuation and the voltage fluctuation in the power system 40, whichever is more significant. The number of allocations can be adjusted appropriately.

In the embodiment shown in FIGS. 9 to 13, as a modification, the deviation ratios V _{sd_pu} and f _{sd_pu} from the allowable range defined by the grid interconnection regulation for the voltage fluctuations and the frequency fluctuations of the power system 40 are evaluated, and the voltage fluctuations and You may make it obtain _{| require} the relative ratio _{Vsd_pu} / _{fsd_pu} of two deviation ratios evaluated about each of frequency fluctuations. Moreover, in this modification, the number of unit allocations of the first unit U1 that preferentially outputs active power when the system is stable and the number of unit allocations of the second unit U2 that preferentially outputs reactive power when the system is stable. the relative proportions between may be set in accordance with relative proportions _{V sd_pu / f sd_pu} deviation ratio described above.

  According to this modification, in order to suppress the voltage fluctuation and the frequency fluctuation as much as possible, the unit of the first unit U1 is in accordance with the contribution ratio of each of the voltage fluctuation and the frequency fluctuation contributing to the system disturbance of the power system 40. The relative ratio between the allocation number and the unit allocation number of the second unit U2 can be appropriately adjusted. Therefore, according to this modified example, in the entire distributed power supply including the plurality of wind power generation units 1a to 1N, the fluctuations of the system voltage and the system frequency are suppressed in consideration of the contribution rate to the system disturbance. It is possible to output the necessary and sufficient active power and reactive power.

1 (1a-1N) Wind power generator unit 10 Wind power generator 20 Interconnection circuit part 21,300 Transformer 40 Power system 51,52 Operating area 100,200 Control device 110 Voltage measuring device 120 (120a-120N) Power converter 130 (130a to 130N) Power control unit 131 Active power control unit 132 Reactive power control unit 140 (140a to 140N) Limit processing unit 150 AVR control unit 160 MPPT control unit 170 Governor control unit 180 Wind speed information sensor 190 Adder 210 (210a to 210N) 210N) Control mode switching unit 220 Allocation number determination unit 221 Provisional number determination unit 223 Allocation number adjustment unit 230 System state calculation unit 240 Unit classification unit CL Control signal line P Active power P1ref First active power command value P2ref Second active power command Value Plim Maximum active power Pref Yes Power command value Q reactive power Q1ref first reactive power command value Q2ref second reactive power command value Qlim maximum reactive power Qref reactive power command value

Claims (14)

A controller of a power converter for matching power from a distributed power source with a power system,
An active power control unit for controlling the power converter to adjust active power supplied from the distributed power supply to the power system;
A reactive power control unit for controlling the power converter to adjust the reactive power supplied from the distributed power source to the power system ,
The control mode of the power converter by the control device is
The maximum reactive power that can be output by the power converter when the first active power command value is given to the active power control unit and the power converter outputs the active power corresponding to the first active power command value. A first control mode in which the following first reactive power command value is given to the reactive power control unit,
The second active power command value is given to the reactive power control unit, and the maximum active power that can be output by the power converter when the power converter outputs the reactive power corresponding to the second reactive power command value. A second control mode in which the following second active power command value is given to the active power control unit,
Only including,
Electric power for a distributed power source including a control mode switching unit configured to switch a control mode between the first control mode and the second control mode based on at least one of a system voltage and a system frequency of the power system. Converter control unit. The control mode switching unit sets the control mode according to whether the system voltage of the power system is within a first specified range or whether the system frequency of the power system is within a second specified range. Configured to switch,
The control device for a power converter for a distributed power source according to claim 1, wherein The control mode switching unit,
When the system voltage deviates from the first specified range, the controller is operated in the first control mode,
The power converter for a distributed power source according to claim 2, wherein the control device is configured to operate in the second control mode when the system frequency deviates from the second specified range. Control device.   When the system voltage deviates from the first specified range and the system frequency deviates from the second specified range, the control mode switching unit outputs the system voltage from the first specified range. One of the first control mode and the second control mode is selected based on a magnitude relationship between a deviation ratio and a deviation ratio of the system frequency from the second specified range. The control device of the power converter for distributed power supplies according to claim 2 or 3. When the system voltage deviates from the first specified range and the system frequency deviates from the second specified range, the control mode switching unit outputs the system voltage from the first specified range. deviation ratio and a second capacitance for the first capacitor and the reactive power for the second effective power capacity of the power converter in accordance with the ratio which is determined based on a deviation ratio of the prescribed range of the system frequency and 5. The method according to claim 2, wherein the active power is limited within the range of the first capacity, and the reactive power is limited within the range of the second capacity. A control device for a power converter for a distributed power supply according to. Further comprising a limit processing unit for calculating the maximum reactive power in the first control mode and the maximum active power in the second control mode,
The limit processing unit,
When the control device operates in the first control mode, the apparent power in the power converter is the capacity of the power converter when the power converter outputs the active power corresponding to the first active power command value. Set the maximum reactive power to a value that matches
During operation of the control device in the second control mode, the apparent power in the power converter matches the capacity when the power converter outputs the reactive power corresponding to the second reactive power command value. The control device for the power converter for distributed power supply according to claim 1, wherein the controller is configured to set the maximum active power to a value. The distributed power source includes one or more wind power generation units, each equipped with a wind power generator,
MPPT control for receiving wind speed information indicating wind speed from each of the wind power generation units and outputting a first control signal for controlling the wind power generator at an optimum operating point according to the wind speed based on at least the wind speed information Department,
A governor control unit that outputs a second control signal for maintaining a system frequency of the power system constant;
An adder that determines the first active power command value based on a control signal obtained by adding the first control signal and the second control signal and outputs the first active power command value to the limit processing unit;
The control device for the power converter for distributed power supply according to claim 6, further comprising: The distributed power source includes one or more wind power generation units, each equipped with a wind power generator,
An AVR control unit that determines the second reactive power command value for maintaining the power generation end voltage of the wind power generator constant and outputs the second reactive power command value to the limit processing unit;
The control device for the power converter for distributed power supply according to claim 6 or 7, further comprising: The distributed power source includes a plurality of wind power generation units each including a wind power generator,
A unit classification unit for classifying the plurality of wind power generation units into at least one or more first unit and one or more second unit other than the first unit and having a wind speed lower than that of the first unit. Further preparation,
The control mode switching unit,
For the first unit, when the system voltage of the power system is within a first specified range, the power converter is controlled in the first control mode as a main control mode, while the system voltage is the first control mode. When the power converter deviates from the specified range, the power converter is controlled in the second control mode as the sub-control mode,
Regarding the second unit, when the system frequency of the power system is within the second specified range, the power converter is controlled in the second control mode as the main control mode, while the system frequency is the first control mode. 9. The power converter is configured to be controlled in the first control mode as a sub-control mode when the power consumption deviates from the 2 specified range. A control device for a power converter for a distributed power supply according to.   Based on the magnitude relationship between the deviation ratio of the system voltage from the first specified range and the deviation ratio of the system voltage from the first specified range, the unit allocation number of the first unit and the second unit. 10. The controller for the power converter for distributed power supply according to claim 9, further comprising an allocation number determination unit for adjusting the unit allocation number of the power converter. The allocation number determination unit,
The provisional number of the first units is determined according to the deviation ratio of the system frequency from the first specified range, and the provisional number of the second units is determined according to the deviation ratio of the system voltage from the second specified range. Decide
When the total of the provisional number of the first unit and the provisional number of the second unit is less than or equal to the total number of the plurality of wind power generation units, the provisional number of the second unit is assigned to the unit allocation number of the second unit. And the number of wind power generation units subtracted from the provisional number of the second unit from the total number of the plurality of wind power generation units is set to the unit allocation number of the first unit, The control device of the power converter for distributed power supplies according to claim 10. The allocation number determination unit,
The provisional number of the first units is determined according to the deviation ratio of the system frequency from the first specified range, and the provisional number of the second units is determined according to the deviation ratio of the system voltage from the second specified range. Decide
When the deviation ratio of the system voltage from the second specified range is larger than the deviation ratio of the system frequency from the first specified range, the provisional number of the second units is set to the unit allocation number of the second unit. , A number obtained by subtracting the provisional number of the second unit from the total number of the plurality of wind power generation units is set as the unit allocation number of the first unit,
If the deviation ratio of the system voltage from the second specified range is less than or equal to the deviation ratio of the system frequency from the first specified range, the provisional number of the first units is set to the unit allocation number of the first unit. Then, the number obtained by subtracting the provisional number of the first unit from the total number of the plurality of wind power generation units is set as the unit allocation number of the second unit,
The control device for a power converter for a distributed power supply according to claim 10 , characterized in that. Distributed power,
A power converter for matching the power from the distributed power supply to a power system,
The control device according to any one of claims 1 to 12 for controlling the power converter,
Distributed power supply system. A method for controlling a power converter for matching power from a distributed power source to a power system,
Controlling the power converter to regulate active power supplied from the distributed power source to the power grid;
Controlling the power converter to regulate reactive power supplied from the distributed power source to the power grid ;
Equipped with a,
Control mode of the power converter,
The power converter with obtaining given a first active power command value to the active power control unit of the control apparatus of the power converter, when the power converter has output the effective power corresponding to the first active power command value A first control mode in which a first reactive power command value that is equal to or less than the maximum reactive power that can be output by the controller is given to the reactive power control unit of the control device ,
The second active power command value is given to the reactive power control unit, and the maximum active power that can be output by the power converter when the power converter outputs the reactive power corresponding to the second reactive power command value. A second control mode in which the following second active power command value is given to the active power control unit,
Only including,
Switching the control mode of the power converter between the first control mode and the second control mode based on at least one of a system voltage or a system frequency of the power system. A method of controlling a power converter for a distributed power supply, which is characterized.

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