JP6425625B2 - Distributed power supply - Google Patents

Description

  The present invention relates to a distributed power supply apparatus in which a plurality of power conditioners (hereinafter referred to as "PCS"), which are power conversion apparatuses, are connected in parallel to perform parallel operation.

  As described in the patent documents 1 to 5 etc., the conventional PCS realizes peak cut control of the grid power at the power receiving point, so the grid power sensor and PCS, peak cut power command value as a set value, etc. And consists of.

  Specifically, the system power value measured (detected) by the system power sensor is input to the PCS and compared with the peak cut power command value so that the system power value does not exceed the peak cut power command value, The PCS supplies the power for the shortage to the load. As a result, the maximum value (upper limit value) of the system power can be suppressed, and the power system can be leveled.

  In the case where a distributed power supply apparatus is configured with a plurality of PCSs by such a conventional method, for example, a circuit configuration as shown in FIG. 2 is obtained.

FIG. 2 is a schematic block diagram showing a conventional distributed power supply device.
The distributed power supply apparatus includes a plurality of PCSs 10 (= 10-1 to 10-n) connected to a plurality of DC power supplies 1 (= 1-1 to 1-n). Each PCS 10 is a device for converting DC power supplied from each DC power source 1 into AC power, and is parallel to the wire 13 between the load 14 and the power receiving point 16 for receiving system power from the power system 17. It is connected to the. The power reception point 16 is provided with a grid power sensor 15 that detects a grid power value pout. The grid power value pout is given to each PCS 10.

  Each PCS 10 is a device that converts DC power supplied from each DC power supply 1 into AC power, and includes a power conversion unit 11 and a control unit 12. The power conversion unit 11 converts direct current power supplied from the direct current power supply 1 into alternating current power based on a control signal supplied from the control unit 12. The control unit 12 obtains an output power target value based on the system power value pout and the peak cut power command value pcut1 of the upper limit of the system power, and the output power value detected from the output power of each PCS 10 and the output A control signal is generated and supplied to the power conversion unit 11 so that an error between the power target value and the power target value is reduced.

  In this type of distributed power supply device, the load power Pz supplied from the power system 17 to the load 14 exceeds the peak cut power command value pcut1 (for example, 50 kW) of the upper limit of the system power received from the power system 17 When the plurality of PCSs 10 supply the output power Pc (= Pc1 to Pcn) to the load 14. As a result, the upper limit value of the system power can be suppressed, and equalization (ie, stabilization) of the power system 17 can be achieved.

JP-A-8-223816 JP 2005-295707 A JP, 2008-43184, A Unexamined-Japanese-Patent No. 2010-55974 JP 2012-33547 A

However, the conventional distributed power supply device has the following problems.
In the conventional distributed power supply apparatus, the grid power value pout is detected by the grid power sensor 15 provided at the power receiving point 16 of the power grid 17, and this grid power value pout is given to a plurality of PCSs 10. Each PCS 10 shares one system power value pout and tries to control the system power value pout to the same peak cut power command value pcut 1, so the difference between the detection error and the control response that each PCS 10 has causes the system power And control of load sharing become impossible.

The distributed power supply device according to the present invention includes a plurality of PCSs connected in parallel to a wire between a load and a power receiving point for receiving system power from the power system and converting DC power into AC power, respectively, Power is supplied from the plurality of PCSs to the load such that load power supplied from the grid to the load does not exceed the first peak cut power command value of the upper limit of the grid power received from the power grid. It is an apparatus.

  Each of the PCS calculates the first peak cut power command value to obtain a second peak cut power command value to be shared for each PCS, and the second peak cut power obtained by the calculation unit An output power target value is obtained based on the command value and the grid power value detected from the grid power, and an error between the output power value detected from the output power of each PCS and the output power target value And a power conversion unit that converts the DC power to the AC power based on the control signal.

  The calculation unit may set a rank setting value for setting a rank of load sharing in the power supplied to the load, a rank change element for changing the rank of the load sharing to drive all the plurality of PCSs, and And calculating the second peak cut power command value by subtracting the adjustment value from the first peak cut power command value.

  According to the distributed power supply device of the present invention, each PCS is provided with a computing unit, and the computing unit obtains an adjustment value based on the rank setting value, the rank change element, and the load sharing power, and performs the first peak cut power command Since the second peak cut power command value is calculated by subtracting the adjustment value from the value, a difference is generated in the second peak cut power command value which is the control target value of each PCS. By this difference, the upper limit value of the grid power can be properly suppressed and leveling (ie, stabilization) of the grid can be achieved because the difference is not affected by the detection error and the variation of control response that each PCS has. .

FIG. 1 is a schematic block diagram showing a distributed power supply device according to a first embodiment of the present invention. FIG. 2 is a schematic block diagram showing a conventional distributed power supply. FIG. 3 is a schematic functional block diagram showing the configuration of the PCS 21 in FIG. FIG. 4 is an explanatory view showing the operation of FIG.

  The mode for carrying out the present invention will be apparent from the following description of the preferred embodiment, when read in conjunction with the attached drawings. However, the drawings are for the purpose of illustration only and do not limit the scope of the present invention.

  When parallel operation is performed by connecting a plurality of PCS's 10 (= 10-1 to 10-n) in parallel to the same power system 17 as shown in FIG. Since the grid power value pout is detected by the grid power sensor 15 and control is performed on the basis of the grid power value pout, the load sharing varies and becomes unmanageable due to the detection error. In order to improve this situation, the distributed power supply apparatus according to the first embodiment has the following configuration.

(Configuration of Example 1)
FIG. 1 is a schematic block diagram showing a distributed power supply device according to a first embodiment of the present invention.

  The distributed power supply apparatus includes a plurality of PCSs 21 (= 21-1 to 21-n, for example, n) connected to a plurality of DC power supplies 20 (= 20-1 to 20-n, for example, n = 5). Equipped with = 5). Each DC power supply 20 is a distributed DC power supply such as a storage battery, a solar cell, or a fuel cell. The plurality of PCSs 21 are devices that respectively convert DC power supplied from each DC power supply 20 into AC power, and the wiring 54 between the power receiving point 57 that receives system power from the power system 58 and the load 55 Connected in parallel. The power reception point 57 is provided with a grid power sensor 56 that detects a grid power value pout.

  The grid power sensor 56 is configured by a power meter, or is configured by an ammeter and a voltmeter. The system power value pout detected by the system power sensor 56 is sent to the first PCS 21-1, and sequentially distributed from the first PCS 21-1 to the next second PCS 21-2, third PCS 21-3, and so on.

  Each PCS 21 includes a power conversion unit 30, a power sensor 36, an arithmetic unit 40, and a control unit 50.

  The power conversion unit 30 converts the direct current power supplied from the direct current power supply 20 into alternating current power based on the plurality of control signals s1 and s2 supplied from the control unit 50. The power sensor 36 detects the output power Pc (= Pc1 to Pcn) of the power conversion unit 30, and provides the output power value po to the control unit 50. The power sensor 36 may be a power meter or an ammeter and a voltmeter It is composed of

The calculation unit 40 calculates a first peak cut power command value pcut1 (for example, 50 kW) given from the outside to obtain a second peak cut power command value pcut2 to be shared for each PCS 21, and this second peak cut power command It has a function of giving the value pcut2 to the control unit 50. The control unit 50 generates a plurality of control signals s1 and s2 based on the second peak cut power command value pcut2 supplied from the calculation unit 40 and the system power value pout detected from the system power, and the power conversion unit Has a function to give 30.
Pz in FIG. 1 is system load power supplied to the load 55.

FIG. 3 is a schematic functional block diagram showing the configuration of the PCS 21 in FIG.
In each PCS 21, the power conversion unit 30 includes, for example, a switching circuit 31 for input, a transformer (hereinafter referred to as “transformer”), a rectifier circuit 33, a filter circuit 34, and a switching circuit 35 for output. .

  The input switching circuit 31 is a circuit which receives DC power output from the DC power supply 20, switches the input DC power to convert it into high frequency AC power, and outputs the AC power to the transformer 32. And a plurality of switching elements that are turned on / off by a plurality of control signals s1. The transformer 32 isolates the input side and the output side of the power conversion unit 30, and the rectifier circuit 33 is connected to the output side of the transformer 32.

  The rectifier circuit 33 is a circuit that converts AC power output from the transformer 32 into DC power, and is configured of a diode bridge circuit or the like, and the filter circuit 34 is connected to the output side. The filter circuit 34 is a circuit that removes and smoothes high frequency components included in the output voltage of the rectifier circuit 33. The filter circuit 34 is formed of an LC circuit or the like, and the output switching circuit 35 is connected to the output side.

  The switching circuit 35 is a circuit that converts the DC power output from the filter circuit 34 into low frequency AC power having the same frequency as that of the power system 58, and performs a plurality of on / off operations by the plurality of control signals s2. The output side is connected to the wiring 54. The wire 54 is provided with a power sensor 36.

  Arithmetic unit 40 sets a rank of load sharing in power supplied to load 55, a rank change element of changing the rank of load sharing to drive all the plurality of PCSs 21, and predetermined load sharing The adjustment value AV is obtained based on the electric power d, and the adjustment value AV is subtracted from the first peak cut power command value pcut1 to calculate a second peak cut power command value pcut2.

  In the calculation unit 40, the rank setting value is a value set based on the machine number a corresponding to each of the plurality of PCSs 21 and the number of operation b of the plurality of PCSs 21. The rank change element is clock information c consisting of any one of year, month, day, hour, minute, and second at the time of system power detection, or a plurality of combinations thereof. Further, the predetermined load sharing power d is a power value for absorbing the detection error of each PCS 21 to provide a difference to the first peak cut power command value pcut1.

The adjustment value AV is determined, for example, according to the following equation (1).
Adjustment value AV = {(# machine number a + clock information c)% operation number b} x load sharing power d
However, “%” means to obtain a remainder.
... (1)

  As described above, in the first embodiment, the machine number a, the operating number b, and the load sharing power d are provided as set values, and the current time that is the clock information c is used. A difference is provided to the second peak cut power command value pcut2. That is, according to the calculation of the equation (1), the second peak cut power command value pcut2 for each PCS 21 has a difference of the load sharing power d, and all become different values.

  The calculation unit 40 of the first embodiment is configured of, for example, a clock 41, a remainder calculation unit 42, a multiplication unit 43, and a subtraction unit 44.

  The clock 41 measures clock information c, and the remainder calculating means 42 is connected to the output side. The remainder calculation means 42 adds the machine number a and the clock information c, divides the number of operation b by the sum to calculate the remainder of the division result, and on the output side, the multiplication means 43 Is connected. The multiplying means 43 calculates the adjustment value AV by multiplying the remainder calculated by the remainder calculating means 42 and the load sharing electric power d, and the subtracting means 44 is connected to this output side. The subtraction means 44 subtracts the adjustment value AV from the first peak cut power command value pcut1 to calculate a second peak cut power command value pcut2, and the control unit 50 is connected to this output side.

  The control unit 50 is configured of a target value calculation unit 51, an error calculation unit 52, and a control signal generation unit 53.

  The target value calculation unit 51 subtracts the grid power value pout from the second peak cut power command value pcut2 to calculate the output power target value e, and the error calculation unit 52 is connected to this output side. . The error calculating means 52 calculates the error f between the output power value po and the output power target value e by calculation, and the control signal generating means 53 is connected to this output side. The control signal generation unit 53 generates a plurality of control signals s1 and s2 having a duty ratio such that the error f decreases, and transmits the plurality of control signals s1 and s2 to the switching circuits 31 and 35 in the power conversion unit 30. For example, it comprises pulse width modulation means (PWM means) and drive means.

  The arithmetic unit 40 and the control unit 50 are configured by a processor or an individual circuit or the like.

(Overall operation of the first embodiment)
In the distributed power supply apparatus shown in FIGS. 1 and 3, when the first peak cut power command value pcut1 of the upper limit of the grid power is externally supplied, the first peak cut power command value pcut1 is calculated in each PCS 21. It is given to the part 40. The grid power of the power grid 58 is supplied to the load 55 via the power receiving point 57 and the wiring 54.

  The grid power value pout detected by the grid power sensor 56 is given to each PCS 21. In the example of FIG. 1, the same value is distributed to the second PCS 21-2, the third PCS 21-3, the fourth PCS 21-4, and the fifth PCS 21-5 in order via the first PCS 21-1.

  If fluctuations in the system load power Pz supplied to the load 55 cause the system power value pout detected by the system power sensor 56 to increase, and if this system power value pout tries to exceed the first peak cut power command value pcut1, The plurality of PCSs 21 operate as follows.

  In the calculation unit 40 in each PCS 21, the remainder calculation means 42 adds the machine number a and the clock information c, divides the addition value by the number b of operations to calculate the remainder of the division result, and calculates this The result is given to the multiplying means 43. The multiplying means 43 multiplies the remainder calculated by the remainder calculating means 42 and the load sharing electric power d to obtain the adjustment value AV of the equation (1), and gives it to the subtracting means 44. The subtracting means 44 subtracts the adjustment value AV from the first peak cut power command value pcut 1 to calculate a second peak cut power command value pcut 2, and supplies the second peak cut power command value pcut 2 to the target value calculation means 51 in each control unit 50.

  The target value calculation unit 51 in each control unit 50 subtracts the grid power value pout detected by the grid power sensor 56 from the second peak cut power command value pcut2 given from the calculation unit 40 to obtain an output power target The value e is calculated and given to the error calculation means 52. The error calculating means 52 calculates an error f between the output power value po detected by the power sensor 36 and the output power target value e, and supplies the error f to the control signal generating means 53. Thus, the control signal generation unit 53 generates a plurality of control signals s1 and s2 having a duty ratio such that the error f decreases, and supplies the control signals s1 and s2 to the power conversion unit 30.

  In each power conversion unit 30, the input switching circuit 31 switches DC power output from the DC power supply 20 based on the plurality of control signals s1 supplied from the control unit 50 and converts it into high frequency AC power. . The converted AC power is converted to DC power by the rectifier circuit 33 through the transformer 32, the high frequency component is removed and smoothed by the filter circuit 34, and the resulting signal is sent to the output switching circuit 35.

  The switching circuit 35 converts the DC power output from the filter circuit 34 into low frequency AC power having the same frequency as that of the power system 58 based on the plurality of control signals s2 supplied from the control unit 50. The converted output power Pc is detected by the power sensor 36, and the output power value po is applied to the control unit 50.

  The control unit 50 controls the system power value pout detected by the system power sensor 56 so as not to exceed the second peak cut power command value pcut2, and a plurality of PCSs 21 operate based on the control signals s1 and s2. Insufficient power is supplied to the load 55. Thereby, the upper limit value of the system power is suppressed, and the power system 58 is leveled.

(Load sharing operation of the PCS of the first embodiment)
4 (a) to 4 (c) are explanatory diagrams showing the operation of the distributed power supply device of FIG.

  4 (a) to 4 (c), FIG. 4 (a) is a load sharing characteristic diagram of the conventional PCS 10 without the parallel operation function, and FIG. 4 (b) is the PCS 21 of the first embodiment with the parallel operation function. FIG. 6C is a diagram showing a calculation example of the second peak cut power command value pcut2 for each PCS 21 of the first embodiment with the parallel operation function, and FIG.

  If power control is individually performed so that the output power Pc (= Pc1 to Pc5) of each PCS 10 (= 10-1 to 10-5) becomes the same target value as in the conventional case shown in FIG. Due to the variation of the detection error, any one of the PCSs 10 performs an operation to bear all the load power Pz. In order to manage load sharing properly, not error, in the first embodiment, control is performed based on the machine number a, the operating number b and the load sharing power d in each PCS 21 and the current time.

  In the first embodiment, an operation image at the time of peak cut supply operation is shown in FIG. For example, in a plurality of PCSs 21 (= 21-1 to 21-5), the system load power Pz is sequentially shared by the plurality of output powers Pc (= Pc1 to Pc5).

  In order to realize the operation of FIG. 4B, the second peak cut power command value pcut2 for each PCS 21 is determined by the calculation unit 40 based on the equation (1). As a result, since the second peak cut power command value pcut2 of each PCS 21 has a difference, the load sharing is controlled in order.

  FIG. 4C shows, for example, a calculation example when the first peak cut power command value pcut1 is 50 kW, the number of operating units b is five, the load sharing power d is 0.3 kW, and the day is adopted as the current time. It is done.

  In (c) of FIG. 4, when the load 55 of the grid power increases and the grid power value pout, which is grid input power, exceeds 48.8 kW, the PCS 21-5 starts to output when the load of the grid power increases. If the PCS rating exceeds 10 kW, the PCS 21-5 alone can not control and the grid power value pout exceeds 48.8 kW. After that, it reaches 49.1 kW and the PCS 21-4 performs output. Similarly, the PCS 21-3, 21-2, 21-1 sequentially outputs.

In addition, since there is a date in the calculation formula, the calculation result of the PCS 21-4 is the lowest 48.8 kW on the next 5th, and is initially responsible for the load power Pz. Similarly, the PCSs 21-3, 21-2, 21-1 and 21-5 sequentially receive the load power Pz.
Load sharing is managed by such an operation.

  On the other hand, even when each DC power supply 20 is combined with electric power originating from wind power generation or hydroelectric power generation in addition to storage batteries and solar cells, control of grid power by this method is possible. When the storage battery is connected to the DC power supply 20-1 and the DC power supplies 20-2 and 20-3 and the solar battery is connected to the DC power supply 20-4 and the DC power supply 20-5 in the case of ○ month 4 in FIG. If the load 55 of the system power increases and the system power value pout exceeds 48.8 kW, the PCS 21-5 tries to start the output, but if the power generated by the solar cell is insufficient due to a defect such as weather, sufficient System power value pout exceeds 48.8 kW. After that, when it reaches 49.1 kW and the PCS 21-4 performs output, the PCS 21-3 starts output when the power supply of the solar cell is insufficient for the same reason and the grid power value pout exceeds 49.4 kW. The control of the grid power value pout is performed.

(Effect of Example 1)
According to the distributed power supply apparatus of the first embodiment, each PCS 21 is provided with the operation unit 40, and the operation unit 40 comprises the order setting value of load sharing consisting of the machine number a and the number b of operations and clock information c. The adjustment value AV is obtained based on the load sharing order change element and the load distribution power d, and the adjustment value AV is subtracted from the first peak cut power command value pcut1 to obtain the second peak cut power command value pcut2 Since the calculation is performed, a difference is generated in the second peak cut power command value pcut2 that is the control target value of each PCS 21. By this difference, the system power is not affected by the detection error and the control response variation of the individual PCSs 21. Therefore, the system power is properly suppressed to the upper limit or lower than the first peak cut power command value pcut1. Leveling can be achieved.

(Modification)
The present invention is not limited to the above-described first embodiment, and various usage modes and modifications are possible. For example, the following (I) and (II) can be used as this form of use or modification.

  (I) The PCS 21 shown in FIG. 3 is not limited to the illustrated configuration. For example, the calculation unit 40 may obtain the adjustment value AV using another equation other than the equation (1). The calculation unit 40 may be provided in the control unit 50. Further, instead of the clock 41 provided in each arithmetic unit 40, a single timepiece that can be shared by a plurality of arithmetic units 40 may be provided, and clock information c of the timepiece may be provided to each arithmetic unit 40. This can simplify the configuration.

  (II) The distributed power supply shown in FIG. 1 and FIG. 3 is not limited to the illustrated configuration. For example, the power conversion unit 30 may be configured by another circuit other than illustrated.

20, 20-1 to 20-n DC power supply 21, 21-1 to 21-n PCS (power converter)
Reference Signs List 30 power conversion unit 36 power sensor 40 calculation unit 41 clock 42 remainder calculation unit 43 multiplication unit 44 subtraction unit 50 control unit 51 target value calculation unit 52 error calculation unit 53 control signal generation unit 55 load 56 grid power sensor 57 reception of grid power Point 58 Power System

Claims (9)

A plurality of power conversion devices connected in parallel to a wire between a load and a power receiving point for receiving system power from the power system, and converting DC power into AC power;
The plurality of power conversion devices are connected to the load such that the load power supplied from the power system to the load does not exceed the first peak cut power command value of the upper limit of the system power received from the power system. A distributed power supply for supplying power,
Each of the power converters
A calculation unit that calculates the first peak cut power command value to obtain a second peak cut power command value to be shared for each of the power conversion devices;
An output power target value is determined based on the second peak cut power command value determined by the calculation unit and the grid power value detected from the grid power, and is detected from the output power of each of the power conversion devices A control unit that generates a control signal that reduces an error between the output power value and the output power target value;
A power conversion unit that converts the DC power to the AC power based on the control signal;
Have
The arithmetic unit is
An order setting value for setting the order of load sharing in the electric power supplied to the load, an order changing element for changing the order of load sharing to drive all of the plurality of power conversion devices, and predetermined load sharing A distributed power supply apparatus, wherein an adjustment value is obtained based on electric power, and the adjustment value is subtracted from the first peak cut power command value to calculate the second peak cut power command value. The rank setting value is a value set based on a machine number corresponding to each of the plurality of power conversion devices, and the number of operating the plurality of power conversion devices,
The rank change element is clock information consisting of any one of year, month, day, hour, minute, second, or a combination thereof in grid power detection time,
The predetermined load sharing power is a power value for absorbing a detection error of each of the power conversion devices to provide a difference to the second peak cut power command value.
The distributed power supply according to claim 1, wherein The adjustment value is
The distributed power supply according to claim 2, wherein the distributed power supply is determined according to the following equation.
Adjustment value = {(machine number + clock information)% number of units operating} × load sharing power
However, “%” means to obtain a remainder. The arithmetic unit is
Remainder calculating means for adding the machine number and the clock information and dividing the number of operation with respect to the added value to calculate the remainder of the division result;
Multiplication means for calculating the adjustment value by multiplying the remainder calculated by the remainder calculation means and the load sharing power;
Subtracting means for calculating the second peak cut power command value by subtracting the adjustment value from the first peak cut power command value;
The distributed power supply according to claim 3, characterized in that:   The distributed power supply device according to any one of claims 1 to 4, wherein the grid power value and the output power value are respectively detected by two power sensors. The distributed power supply device according to any one of claims 2 to 4 , wherein the clock information is measured by a clock. The control unit
Target value calculation means for calculating the output power target value by subtracting the grid power value from the second peak cut power command value;
Error calculation means for calculating an error between the output power value and the output power target value by calculation;
Control signal generating means for generating the control signal having a duty ratio such that the error decreases;
The distributed power supply device according to any one of claims 1 to 6, characterized in that   The distributed power supply according to any one of claims 1 to 7, wherein the calculation unit and the control unit are configured by a processor or an individual circuit. The DC power input to each of the power conversion devices is
The distributed power supply according to any one of claims 1 to 8, which is supplied from a distributed DC power supply including a storage battery, a solar cell and a fuel cell.

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