JP4894906B2 - Wind power generation system control method - Google Patents

Description

  The present invention relates to a method for controlling a power generation system connected to a power system, and more particularly to a method for controlling a wind power generation system.

  When an abnormality such as voltage or frequency occurs in the power system, the wind power generation system stops power generation operation and stops power transmission in order to protect the constituent devices. At this time, the wind power generation system disconnects the main circuit of the wind power generation system from the power system by opening an electromagnetic switch between the power system, the power converter, and the generator.

  At this time, since the wind power generation system cannot output electric power from the generator, wind energy is stored as rotational energy, and the windmill may be over-rotated.

  In Patent Document 1, in order to prevent such over-rotation of the windmill, when a power system accident is detected, the pitch angle of the windmill is changed to a feather state, and an overcurrent to the converter is detected by a crowbar circuit. Preventing is described.

WO2004 / 0697958

  When an abnormality occurs in the power system and each wind power generation system is disconnected from the power system, and then the power system abnormality is resolved, the wind turbine is stopped or There is a possibility that the rotation speed is lower than required for power generation operation. Therefore, it takes time until the wind turbine is set to a rotation speed suitable for power generation after the abnormality of the power system is resolved and the power generation operation is resumed, and the power generation operation cannot be resumed immediately.

  For this reason, there has been a problem in that power generation cannot be performed for a long time after the abnormality of the power system is resolved until the windmill has a rotational speed suitable for power generation.

  Furthermore, in a power system in which the ratio of the wind power generation system in the power generation system constituting the power system is large, immediately after the abnormality of the power system is resolved, it becomes a state equivalent to losing a large-scale power generation system for a long time, There has been a problem that the balance between power supply and demand is lost, frequency fluctuations and voltage fluctuations occur, and in some cases there is a possibility of causing a power failure.

  An object of the present invention is to provide a control method for a wind power generation system capable of shortening the time from when the system abnormality is resolved until the wind power generation system resumes the power generation operation when the system abnormality occurs. That is.

  An object of the present invention is to rotate the rotor by changing the pitch angle of the blade when the detected value of the voltage, current and frequency of the power system or the current of the wind power generation system is an abnormal value. This can be achieved by a wind power generation system control method characterized in that the speed is controlled within a certain range, and the generator-side converter controls the reactive power to the synchronous generator.

  After the power system abnormality is resolved, the wind power generation system that has suspended power generation operation can shorten the time until the power generation operation is restarted, which can increase the amount of power generated by the wind power generation system. it can.

The block diagram of the wind power generation system using a secondary excitation type generator. The block diagram of the wind power generation system using a permanent magnet type generator or an induction generator. The block diagram of the wind power generation system using a secondary excitation type generator. The block diagram of a pitch angle control system and a power control system. The figure which showed the relationship between the average wind speed at the time of normal electric power generation, generated electric power, and a pitch angle control system. The figure which showed the pitch angle command and electric power command calculation at the time of normal electric power generation. The figure which showed the detection method of the abnormal state. The figure which showed the detection method of the abnormal state. The figure which showed the preparation method of the pitch angle command in the driving | operation continuation mode at the time of abnormality. The figure which showed the behavior of the pitch angle and the rotational speed in the abnormal operation mode. The figure which showed the preparation method of the pitch angle command in the driving | operation continuation mode at the time of abnormality. The figure which showed the behavior of the pitch angle and the rotational speed in the abnormal operation mode. The figure which showed the preparation method of the pitch angle command in the driving | operation continuation mode at the time of abnormality. The figure which showed the behavior of the pitch angle and the rotational speed in the abnormal operation mode. The figure which showed the controller which comprises a wind power generation system, and its auxiliary power supply. The block diagram of the wind power generation system using a permanent magnet generator or an induction type generator. The block diagram of the wind power generation system using a direct current excitation type synchronous generator. The block diagram of a pitch angle control system and a power control system. The figure which showed pitch angle command and electric power command calculation. The figure which showed the behavior of the system voltage amplitude and the pitch angle during the system voltage drop. The block diagram of the wind power generation system using a permanent magnet generator. The figure which showed the structure of the system side power converter. The figure which showed the behavior of the system voltage amplitude and the power converter output current in system voltage fall. The figure which showed the operating method of the wind power generation system at the time of overcurrent detection. The figure which showed the relationship between the generator terminal voltage and reactive power at the time of field weakening driving | operation. The figure which showed the relationship between the generator terminal voltage and reactive power at the time of weak field operation and strong field operation.

  In the wind power generation system, a device for detecting the system voltage is provided, and the pitch angle control method is changed according to the rate of decrease in the system voltage amplitude.

  The structure of the wind power generation system of this invention is demonstrated using FIGS. 1-16. FIG. 1 shows the configuration of the entire wind power generation system. The wind power generation system shown in FIG. 1 receives wind by a blade 11 and converts wind energy into rotational energy. The rotational energy rotates the hub 12 to which the blade 11 is connected. A rotating part including the blade 11 and the hub 12 is referred to as a rotor 1. The rotation of the rotor 1 is transmitted to the speed increasing gear 22 through the shaft 21. The speed increasing gear 22 converts the rotational speed of the rotor 1 into a rotational speed suitable for the generator. FIG. 1 shows a secondary excitation generator 23 as a generator. In the secondary excitation generator 23, a power system is connected to the stator winding, and a power converter 28 is connected to the rotor winding via a slip ring. In addition, as shown in FIG. 2, this invention can be utilized even if a generator is a permanent magnet type | mold generator 23a, an induction generator, or a synchronous machine.

Next, an outline of the configuration of the control system during the power generation operation of the wind power generation system will be described. FIG. 3 schematically shows a detailed configuration of the secondary excitation generator type wind power generation system including the control system. The control system is mainly configured by an upper wind turbine controller 25 that controls the movement of the entire wind turbine power generation system and a power converter controller 26 that controls the power converter 28. The upper wind turbine controller 25 generates a power generation command from the wind speed measured by the anemometer 24, the rotational speed ω [rad / sec] of the rotor 1 calculated from the pulse signal of the encoder 27, and the generated power P [W] of the wind power generation system. P ^* [W] and pitch angle command φ ^* [degree] are calculated.

The generated power P of the wind power generation system is controlled by a power converter controller 26 and a power converter 28. The power converter 28 includes a generator-side power converter 281, a system-side power converter 283, a smoothing capacitor 282, and the like. The generator side power converter 281 and the system side power converter 283 are configured using semiconductor switching elements such as IGBTs. The converter controller 26 receives three-phase AC voltage values V _U , V _V , and V _W [V] from the voltage measuring device 291 and the current measuring device 292 installed at the connection point between the wind power generation system and the power system. The three-phase current values I _U , I _V , and I _W [A] are taken in. The power converter controller 26 internally calculates a voltage amplitude value V _abs , active power P, reactive power Q, and the like from these voltage and current signals.

In the calculation, the power converter controller 26 temporarily converts the detected voltage and current signals in the rotating coordinate system, and calculates the d-axis component and the q-axis component. For the coordinate conversion, phase signals cos (ω _SYS t) and sin (ω _SYS t) that follow the U phase of the system voltage are used. Here, ω _SYS [rad / sec] represents the angular frequency of the AC voltage of the power system, and t [sec] represents time. When the phase signal cos (ω _SYS t) matches the voltage phase of the U phase of the power system, the voltage d-axis component V _d , the voltage q-axis component V _q , the current d-axis component I _d , The q-axis component I _q is calculated by Equation 1 and Equation 2.

Using the obtained I _d , I _q , V _d , and V _q , the power converter controller 26 uses the active power P [W], the reactive power Q [Var], the voltage amplitude value _Vabs [Vrms], and the current amplitude. The value Iabs [Arms] is obtained from the equations shown in Equation 3, Equation 4, Equation 5, and Equation 6, respectively.

When the phase signal is generated so that the q component of the voltage becomes 0 (V _q = 0), the active power, the reactive power, and the voltage amplitude are expressed as in Expression 7, Expression 8, and Expression 9.

  The power converter controller 26 controls the output current of the generator-side power converter 281 so that the active power P follows the power command from the higher wind turbine controller 25. For this reason, the power converter controller 26 captures the current value detected by the current measuring device 294. At the same time, the system side power converter 283 maintains the DC voltage of the power converter 28 at a predetermined value by controlling the output current. For this reason, the power converter controller 26 captures the current value detected by the current measuring device 293. The power converter controller 26 sends a gate pulse signal in accordance with PWM (pulse width modulation) control to the power converter 28, and the power converter 28 performs a switching operation according to the gate pulse signal, so that the wind power generation system is effective. Controls power and reactive power. The power converter controller 26 calculates the rotational speed ω of the rotor 1 by converting the rotational speed of the generator and the gear ratio from the pulse signal of the encoder 27 attached to the generator. The above is the control method in the normal power generation operation of the wind power generation system (in the present invention, the normal power generation operation means an operation method in a state where no abnormality of the wind power generation system or the power system is detected). is there.

Next, the pitch angle control system of the present invention will be described. A configuration diagram of the pitch angle control system is shown in FIG. The upper wind turbine controller 25 averages the wind speed value measured by the anemometer 24 in the averaging calculator 2501 to obtain an average value v [m / sec] of the wind speed. The upper wind turbine controller 25 creates a rotational speed command ω ^* by referring to a table from the obtained average value v [m / sec] of the wind speed in the rotational speed command calculator 2502. The upper wind turbine controller 25 calculates the generated power command P ^* [W] and the pitch angle of the blade 11 from the obtained rotational speed command ω ^* , the rotational speed ω [rad / sec] of the rotor 1 and the generated power P [W]. Command φ ^* [degree] is calculated. The pitch angle controller 111 controls the pitch angle of the blade 11 in accordance with the pitch angle command φ ^* [degree] from the higher wind turbine controller 25. The characteristic part of the present invention is that the normal power generation operation and the abnormal operation continuation mode (in the present invention, the abnormal operation continuation mode means an operation mode after detecting an abnormality in the wind power generation system or the power system). In this case, the pitch angle control method and the generated power control method are switched. Specifically, during normal power generation operation, the pitch angle command φ ^* and the power command P ^* each use values created by the pitch angle command / power command calculator 2503 (φ ^* = φ ₁ ^* , P ^* = P ₁ ^* ). In abnormal operation continuation mode, the pitch angle command uses the value created by the abnormal pitch angle command calculator (φ ^* = φ ₂
^* ) The generated power command is 0 [W] (P ^* = 0).

  The pitch angle control plays a role of controlling the rotation speed of the rotor 1. The overall energy balance of the rotor 1 is expressed by Equation 10.

The meanings of the symbols in Equation 10 are respectively I [kg · m ² ]: moment of inertia of the rotating body, ω [rad / sec]: rotational speed of the rotor 1, P _in [W]: input power from the wind, P [W]: generated power of the wind power generation system, P _LOSS : loss, t [sec]: time, d / dt: differential operator. As the number 10, in order to control the rotational speed ω of the rotor 1, it is necessary to change the P under the control of either or power output varying the P _in the pitch control of the pitch controller.

FIG. 5 shows the relationship between the wind speed v, the pitch angle control method, and the generated power P during normal power generation operation. A wind power generation system has a wind speed region in which power generation operation is possible due to its characteristics. When the average wind speed is larger than v _ci (cut-in wind speed), the power generation operation is started. Conversely, when the wind speed is smaller than v _ci , the wind power generation system fixes the pitch angle to a predetermined value and is in a standby state without generating power. The generated power increases as the wind speed increases, and becomes substantially constant above v _r (rated wind speed). Under conditions where the wind speed is greater than v _CO (cutout wind speed), the wind power generation system can reduce the input energy of the wind by making the blade 11 parallel to the wind as much as possible (φ = 0 [degree], feather state). Minimize and stand by without generating electricity.

The pitch angle control method during power generation operation is roughly classified as follows according to the wind speed. Between the average value v of the wind speed of v _ci <v <v _r, the pitch angle is the maximum value with respect to the wind direction (phi = 30 [degrees]), By doing so, the energy blade 11 of wind Can be used to the maximum. During this time, the rotational speed of the rotor changes due to instantaneous fluctuations in the wind speed, but fluctuations in the rotational speed ω are suppressed by controlling the generated power P output from the wind power generation system. On the other hand, during v _r <v <v _C0 , the upper wind turbine controller 25 fixes the generated power command P to the rated generated power value. The generated power P of the wind power generation system is controlled to be constant by the power converter 28. During this time, the rotational speed ω is controlled by changing the pitch angle.

FIG. 6 shows a detailed procedure for creating the pitch angle command φ ^* [degree] and the generated power command P ^* [W] during the normal power generation operation. The pitch angle command calculator 25032 creates a pitch angle command φ1 ^* (= φ ^* ) from the rotational speed command value ω ^* and the detected rotational speed value ω. At the same time, the generated power command calculator 25034 creates a generated power command P1 ^* (= P ^* ) from the rotational speed command value ω ^* , the detected rotational speed value ω, and the generated power amount P.

  Next, the pitch angle control method at the time of abnormality detection in the present invention will be described. At the time of abnormality detection, the wind power generation system stops the supply of generated power to the power system 6 (P = 0). For this reason, as apparent from the equation (10), it is difficult to control the rotational speed by power control, and the rotational speed control depends on the pitch angle control having a relatively slow response speed, so that special control is required. Phenomena that are subject to abnormality include system voltage drop, system voltage rise, converter overcurrent, system frequency fluctuation, and the like.

  First, of the abnormal phenomena, the system voltage drop will be described. In the power system, the voltage of the transmission line may temporarily decrease due to lightning strikes, contact of the transmission line with trees, load failure, phase-to-phase contact of the transmission line due to human disasters, and the like. The voltage drop phenomenon can be resolved within a few seconds by shutting off the accident section if it is a minor accident.

  As a similar abnormal phenomenon of the system voltage, an increase in the system voltage may occur. The cause of the system voltage rise is caused by an inrush current generated instantaneously when the load and the generator are connected to the power system.

  When such an instantaneous voltage drop or voltage rise occurs, the wind power generation system stops the power generation operation. This is to protect the wind power generation system components.

The detection of the abnormal state of the voltage is performed inside the power converter controller 26 that controls the power converter 28. A mechanism for detecting an abnormal voltage state will be described with reference to FIG. The power converter controller 26 performs the calculations shown in Equations 2 and 5 by the voltage amplitude calculator 2602 in the power converter controller 26 to obtain the system voltage amplitude V _abs . The power converter controller 26 holds a voltage level V _GF that is determined to be a system _fault inside, and constantly compares the system voltage amplitude V _abs obtained from the calculation with V _GF during operation. The comparison is performed by the comparison calculator 2604 in the power converter controller 26. When V _abs <V _GF is satisfied, it is determined that the system voltage is abnormal, and a low voltage detection signal is generated. The detection of the overvoltage of the system voltage is also performed with the same configuration. In other words, the power converter controller 26 maintains the overvoltage level V _OV inside, and always compares V _abs and V _OV . When the relationship of V _abs > V _OV is established, it is determined that the system voltage is in an overvoltage state, and an overvoltage detection signal is generated.

  Next, an overcurrent phenomenon will be described as an abnormal phenomenon. If the wind power generation system is in the range of normal power generation operation, the output current amplitude is less than the rated current. However, an excessive current that greatly exceeds the rated current may flow due to a system fault or the like. This phenomenon is hereinafter referred to as overcurrent. When the current amplitude at the time of overcurrent reaches 1.5 to 2 times the rated current of the wind power generation system, the semiconductor element that is a component device of the power converter 28 may be destroyed. For this reason, when an overcurrent is detected in the power converter or the wind power generation system, the power converter 28 needs to stop operation instantaneously and the wind power generation system needs to shift to the standby mode. Note that. When the cause of the overcurrent is a short-time accident in the power system, it may be desirable from the viewpoint of power system stabilization to restart the power generation operation immediately after the reduction of the overcurrent.

The overcurrent detection method will be described with reference to FIG. The overcurrent is detected by an overcurrent detection calculator 26005a of the power converter controller 26. The power converter controller 26 performs the calculations shown in Equations 1 and 6 by the current amplitude calculator 2605 in the overcurrent detection calculator 26005a to obtain the output current amplitude I _abs . The power converter controller 26 holds a current amplitude level I _OC that is determined to be an overcurrent. The current amplitude level I _OC is normally set to 1.5 to 2.0 times the power generation system rated current amplitude. The power converter controller 26 constantly compares I _OC and I _abs during operation in a comparison calculator 2606 for internal calculation. When I _abs > I _OC holds, it is determined that the current is in an overcurrent state, and an overcurrent detection signal is generated. Although the overcurrent detection method of the output current (I _U , I _V , I _W ) of the entire wind power generation system detected by the current measuring device 292 has been described above, the same method as the overcurrent detection calculator 26005a is used. The overcurrent phenomenon of the power converter 28 is also detected. The grid-side power converter 283, the overcurrent detection calculator 26005B, the output current of the current measuring device 293 is detected by the grid-side power converter _{283 (I sU, I sV,} I sW) with the overcurrent To detect. For generator-side power converter 281, the overcurrent detection calculator 26005C, the output current of the generator-side power converter 281 detected by the current measuring device _{294 (I gU, I gV,} I gW) with, over Detect current.

  Variations in system frequency are also subject to abnormality detection. The operating frequency of the power system is determined by each power system, and if the power system is in a normal state, it does not deviate significantly from the operating frequency. However, the frequency may fluctuate greatly due to a system fault or the like. In such a case, since current control in the wind power generation system may be difficult, the power generation operation is stopped to protect the wind power generation system.

A configuration for detecting fluctuations in the system frequency will be described with reference to FIG. In the internal system frequency detector 2607, the power converter controller 26 detects the frequency ω _{SYS of the} power system from the detected value of the system voltage. The power converter controller 26 holds the upper limit frequency omega _SYSH, and the lower limit omega _sysl therein. The power converter controller 26 constantly compares ω _SYS with ω _SYSH , ω _SYSL in the comparison calculator 2608 and the comparison calculator 2609 during operation, and _sets ω _SYS > ω _SYSH or ω _SYS <ω _SYSL . If detected, a large frequency fluctuation signal is generated.

The abnormality detection method shown in FIG. 7 is all performed by the internal calculation of the power converter controller 26, but may be configured by an electric circuit as shown in FIG. In FIG. 8, an overcurrent abnormality is detected by an overcurrent detection circuit 26006a constituted by an absolute value calculation circuit 2610a and a comparator 2616a. In FIG. 8, the current peak value is detected from the detected current values I _U , I _V , and I _{W of} the three phases by using the absolute value calculation circuits 2610a, 2611a, and 2612a and the diodes 2613a, 2614a, and 2615a. The current peak value is compared with the overcurrent level I _OC in the comparator 2616a, thereby detecting the overcurrent. The overcurrent level I _OC is set by a 5V voltage source, a resistor 2618a, and a variable resistor 2617a. The overcurrent of the power converter 28 is also detected by the overcurrent detection circuit 26006b and the overcurrent detection circuit 26006c having the same circuit configuration. Although not shown in FIG. 8, an overvoltage phenomenon can be detected with a similar electric circuit configuration.

  The power converter controller 26 stops the gate pulse signal for operating the power converter when detecting at least one of the abnormality detection signals (overcurrent, voltage abnormality, frequency abnormality). This operation is called a gate block. At the same time, an abnormality detection signal is transmitted to the upper wind turbine controller. When detecting the abnormality detection signal, the upper wind turbine controller shifts the entire wind power generation system to the abnormal operation continuation mode.

The pitch angle control method during the abnormal operation continuation mode in the present invention will be described below. In order for the wind power generation system to immediately shift to the power generation operation state after the abnormal state is resolved, it is necessary to maintain the rotation speed of the rotor 1 within a range in which the power generation operation can be performed even during the abnormal operation continuation mode. Necessary. The rotation speed control of the rotor 1 is performed by pitch angle control and generated power control. The pitch angle control is performed by the pitch angle controller 111 shown in FIG. The pitch angle controller 111 is configured by an electric motor or a hydraulic drive system. Pitch angle control requires about several tens of seconds to change from the feather state (φ = 0 [degrees]) to the maximum angle (φ = 30 [degrees]). On the other hand, the generated power control takes about several hundreds msec to change from 0 to the rating. For this reason, the rotational speed control is faster in the generated power control than in the pitch angle control.

  Since the wind power generation system stops the power generation operation during the abnormal operation continuation mode after the abnormal state is detected, the generated power is not supplied to the power system. At this time, since P = 0 in Equation 10, the rotation speed must be controlled only by the pitch angle control with a slow response, and the rotation speed easily deviates from the operating range with the normal pitch control. . In particular, when an abnormal state is detected during rated power generation operation, P in Formula 10 rapidly changes from the rated generated power to 0 [W], and thus the rotational speed ω increases rapidly. In order to suppress the increase in the rotational speed ω, a pitch angle control method different from that during normal power generation operation is required.

FIG. 9 shows an example of the pitch angle control method during the abnormal operation continuation mode after the abnormal state is detected. During the abnormal operation continuation mode, the pitch angle control method is switched according to the detected value ω of the rotational speed. Specifically, the pitch angle control method is switched by providing two levels ω _a and ω _b to the rotational speed and comparing the two levels with the rotational speed detection value ω. Note that the relationship shown in Expression 11 is established between ω _a and ω _b and the upper limit ω _H and lower limit ω _L of the operable rotational speed.

While the detected value of the rotational speed is in the relationship of ω _a ≦ ω ≦ ω _b , the pitch control is performed by the PI controller 25063. The PI controller 25063 determines a pitch angle command φ ₂ ^* (= φ ^* ) by performing a proportional-integral operation on the difference between the target value ω ^* of the rotational speed and the detected rotational speed value ω. In the case of omega <omega _a is the pitch angle command selector 25064 selects the best angle phi ₂ ^* = 30 receive the wind energy [degrees] as the pitch angle command. Similarly, when ω> ω _b , the pitch angle command selector 25064 selects an angle φ ₂ ^* = 0 [degrees] that receives the least wind energy as the pitch angle command.

FIG. 10 shows how the rotation speed and the pitch angle change with time. In FIG. 10, an abnormal state is detected at time t ₁ and power generation is stopped. At the moment of abnormality detection, the rotational speed has a relationship of ω> ω _b , so that φ ^* = 0 [degree] is selected as each pitch command. In this way, when the rotational speed approaches the upper limit of the operable range, the input energy of the wind can be rapidly attenuated, so that the rotational speed decreases, and the rotational speed exceeds the upper limit ω _{H of the} rotational speed. It can be prevented from exceeding. During the time t ₂ <t <t ₃ , there is a relationship of ω _a <ω <ω _b , and the pitch angle command by PI control is followed. During t ₃ <t <t ₄ , ω <ω _a, which is in a region where the lower limit of the operation speed is easily reached. In this case, φ ^* = 30 [degrees] is selected as the pitch angle command. Thereby, since the energy input energy of the wind can be increased rapidly, the rotation speed can be increased and the rotation speed ω can be prevented from falling below the lower limit ω _{L of the} rotation speed.

As another pitch angle control method during the abnormal operation continuation mode, the method shown in FIG. 11 may be used. In the method shown in FIG. 11, during the abnormal operation continuation mode, a predetermined pitch angle command is selected according to the detected value ω of the rotational speed. Specifically, omega <omega a is φ ^* = 30 [degrees] when _a, when the _{ω a ≦ ω ≦ ω b φ} * = 15 [ degrees], omega> when the ω _b φ ^* = 0 [degrees Select.

FIG. 12 shows the movements of the rotational speed ω and the pitch angle φ when the pitch angle control method shown in FIG. 11 is performed. In the example of FIG. 12, an abnormal state is detected at time t ₁ and power generation is stopped, and thereafter, the operation continues in the abnormal time operation mode. During the abnormal operation continuation mode, a three-step pitch angle command is selected according to the magnitude of the rotational speed. During the time t ₁ <t <t ₂ , the rotational speed is ω> ω _b , which is close to the upper limit of the operable range. Therefore, by selecting φ ^* = 0 [degree] as the pitch angle command, the inflow of wind Attenuates energy and prevents the rotation speed from deviating from the upper limit. Conversely, during t ₃ <t <t ₄ , the rotational speed becomes ω <ω _a and approaches the lower limit of the operable range, so φ ^* = 30 [degrees] is selected as the pitch angle command. This increases the inflow energy of the wind and prevents the rotation speed from deviating from the lower limit.

Further, as another pitch angle control method in the abnormal operation continuation mode, the method shown in FIG. 13 may be used. In the pitch angle control method shown in FIG. 13, the rotational speed command value ω ^* is fixed to a constant value ω _C regardless of the wind speed during the abnormal operation continuation mode. ω _C is set to an intermediate value between the upper limit ω _H and the lower limit ω _L of the operable rotational speed. The pitch angle command φ ₂ is created by performing PI control calculation on the difference between the rotational speed command value ω _C and the detected rotational speed value ω. FIG. 14 shows the movement of the rotational speed ω and the pitch angle φ when the pitch angle control shown in FIG. 13 is performed. In the example of FIG. 14, an abnormal state is detected at time t ₁ , power generation is stopped, and thereafter, the operation continues in the abnormal time operation mode. During the abnormal operation continuation mode, the target value ω ^* of the rotational speed is a constant value regardless of the wind speed. By doing in this way, it becomes difficult for the rotational speed of the rotor 1 to deviate from the area | region which can be drive | operated. In the above configuration, the pitch angle is fixed to the feather state (pitch angle φ = 0 [degrees]) in the region where the rotational speed of the rotor 1 is high, but may be fixed to a predetermined value near the feather state. A similar over-rotation preventing effect can be obtained.

  In the abnormal phenomenon, when the system voltage is reduced, the control power of the wind power generation system cannot be supplied from the power system. For this reason, as shown in FIG. 15, the controllers (the upper wind turbine controller 25, the pitch angle controller 111, the power converter controller 26, etc.) constituting the wind power generation system each include an auxiliary power source. When the voltage drop phenomenon of the power system does not occur, the power of the controller is stepped down from AC 6.6 kV (or 1.4 kV) of the power system to AC 200 V (or AC 400 V) by the step-down transformer 41, It is supplied via auxiliary power supplies 30a, 30b, 30c. Auxiliary power supplies 30a, 30b, and 30c are provided with power storage equipment such as storage batteries, and supply power to the controller from the power system when the voltage drop phenomenon of the power system does not occur. The battery is being charged.

  When a voltage drop phenomenon of the power system occurs and power cannot be supplied from the power system to the controller (the upper wind turbine controller 25, the pitch angle controller 111, the power converter controller 26, etc.), the auxiliary power supplies 30a, 30b, 30c supplies electric power to the control power supply from the internal power storage facility. With the configuration having such an auxiliary power supply, the controller can secure power even when the system voltage is being lowered, and can operate in the operation continuation mode at the time of abnormality.

  Note that the pitch angle control method during the abnormal operation continuation mode as described above is not limited to the secondary excitation generator type wind power generation system, but also the permanent magnet generator type wind power generation system and induction generator shown in FIG. The present invention can also be applied to a type wind power generation system, a direct current excitation synchronous generator type wind power generation system shown in FIG.

  As described above, the pitch angle control method is switched from the normal power generation operation control method to the abnormal operation continuation mode in the abnormal operation continuation mode after the abnormality is detected, and the pitch angle command is changed according to the rotational speed of the windmill. The pitch angle command is adjusted in order to control the rotation speed to a constant target value. By such a pitch angle control method, the rotational speed of the rotor 1 can be easily kept within the operable range even during the abnormal operation continuation mode in which the rotational speed control of the rotor 1 needs to be performed only by adjusting the pitch angle. Thus, after the abnormal state is resolved, it is possible to immediately shift to the normal power generation operation state. Thereby, the power generation operation time of the wind power generation system can be extended, and the power generation amount increases. In addition, power supply immediately after a system failure can contribute to the stabilization of the entire power system.

  Examples of the present invention will be described. In this embodiment, the pitch angle control method is changed according to the rate of decrease in the system voltage.

  The present invention can be applied to a wind power generation system having the power converter 28 as a component and capable of controlling generated power as shown in FIGS. Since the pitch angle control and the generated power control during the normal power generation operation are as described in the first embodiment, the description thereof is omitted.

  The operation method of the wind power generation system during the system voltage drop in the present invention will be described below. In the power system, the voltage of the transmission line may temporarily decrease due to lightning strikes, contact of the transmission line with trees, load failure, phase-to-phase contact of the transmission line due to human disasters, and the like. In the case of a minor accident, the voltage drop phenomenon is often resolved within a few seconds by interrupting the accident section.

When the wind power generation system supplies the generated power to the power system even when the system voltage is lowered, the following advantages are obtained. That is, as shown in Equation 10, the rotational speed of the rotor 1 of the wind power generation system is mainly determined by the input power P _in [W] from the wind and the generated power P [W] of the power generation system. For example, if the generated power cannot be supplied to the power system during a grid fault, P = 0 in Formula 10 and the rotational speed ω increases rapidly. On the other hand, even during a system failure, if the generated power P can be supplied to the power system, the increase in the rotational speed ω becomes slow. The rising speed of the rotational speed ω varies depending on the difference in the magnitude of the generated power.

Next, the relationship between the system voltage and the generated power P will be described. Since the system voltage V _abs = | V _d | shown in Equation 9 is reduced during the system voltage sag, the generated power P can be obtained even if the same current I _{d as} that before the accident flows as shown in Equation 7. Get smaller. In order to keep the generated power P at the same value as before the accident, it is necessary to increase the output current I _d , but there is a limit due to restrictions from the power converter 28 and the generator. When the maximum value of the current value that can be output from the power converter 28 is I _MAX [Arms], the maximum value P _MAX [W] of the power generation amount of the wind power generation system is proportional to the system voltage, as shown in Equation 12. To do.

For this reason, it is necessary to change the pitch angle control system for preventing the rotation speed from increasing depending on the rate of decrease of the system voltage. For example, in the case of an accident in which the system voltage becomes 0, V _d in Equation 7 is almost 0, so the power P that can be supplied to the power system is also almost 0. For this reason, in order to suppress the increase in the rotational speed, it is necessary to rapidly reduce the input power Pin _in Equation 10. That is, it is necessary to change the pitch angle in a direction parallel to the wind direction (feather direction).

On the other hand, when the system voltage drops only to about 80% of the normal time, almost all generated power can be supplied to the power system even when the system is abnormal. That is, the decrease in the generated power P in Equation 10 is small, and the increase in rotational speed is also gradual. Pitch control also, it is not necessary to reduce rapidly the input power P _in, be in a range to maintain the normal control system shown in FIG. 4, or wind conditions v _ci <v of <v _r, Only when the rotational speed exceeds the upper limit, it is sufficient to perform pitch angle control that suppresses over-rotation.

FIG. 18 shows a configuration diagram of the pitch angle control system and the power controller system in the present embodiment. The upper windmill controller 25d averages the wind speed value measured by the anemometer 24d in the averaging calculator 2501d to obtain an average wind speed value v [m / sec]. The host wind turbine controller 25d creates a rotational speed command ω ^* by referring to a table from the average value v [m / sec] of the obtained wind speed in the rotational speed command calculator 2502d. The upper wind turbine controller 25d determines the generated power command P from the obtained rotational speed command ω ^* , the detected rotational speed value ω [rad / sec] of the rotor 1, the generated power P [W], and the system voltage amplitude V _abs [W]. ^* A pitch angle command φ ^* [degree] of the blade 11 is calculated together with [W]. The pitch angle controller 111d controls the pitch angle of the blade 11 in accordance with the pitch angle command φ ^* [degree] from the higher wind turbine controller 25d.

The operation of the pitch angle command / power command calculator 2503d will be described with reference to FIG. The present invention is characterized in that the pitch angle control method is switched according to the magnitude of the voltage drop. Specifically, during a system fault, the system voltage is divided into three stages, and the pitch angle control method is changed in each region. Assuming that the normal system voltage is 100%, the voltage range of the transmission line is approximately 90% to 110%, although it varies depending on the regulations of the system operator. Here, it is determined that V _GF = 90% or less is a system fault condition, and the period at the time of the system fault is further divided into three according to the magnitude of the system voltage.

For example, when the system voltage is between V _GF (= 90%) and V _abs2 (= 80%), almost all generated power can be supplied to the power system even during a system _fault . There is almost no increase in rotational speed. In the pitch angle control, a control method during normal operation according to the wind speed is continued, and a pitch angle command is created according to ω and ω ^* .

When the system voltage is between V _abs2 [%] (80%) and V _abs1 [%] (20%), the pitch angle is rapidly changed to a preset angle φ = 15 [degrees] and fixed. To do. Note that the predetermined angle is a value that is approximately between the maximum value of the pitch angle and the feather state. By controlling the pitch angle in this way, part of the input energy of the wind is released to prevent over-rotation and the rotation of the rotor is maintained even during the accident period. It is possible to do.

When the system voltage is less than V _abs1 [%] (= 20 [%]), almost no generated power can be supplied to the power system, so the rotational speed ω of the rotor 1 rapidly increases. In order to suppress an increase in the rotational speed, the pitch angle controller 111 rapidly changes the pitch angle to the feather state φ ^* = 0 [degrees]. Regarding the generated power command P ^* , the maximum power command calculator 25037d calculates the maximum generated power amount P _max that can be generated according to Equation 7, and the limiter 25036d limits the generated power command P ^* .

FIG. 20 shows a time change of the pitch angle command when the pitch angle control method shown in FIGS. 18 and 19 is applied. In FIG. 20, the horizontal axis indicates time, and the vertical axis indicates the system voltage amplitude and pitch angle command. In FIG. 20, the system voltage amplitude becomes V _abs <V _{GF at} time t ₁ , but the pitch angle control method performs the pitch angle control according to the rotation speed as in the normal power generation operation. Between times t ₂ <t <t ₃ and t ₄ <t <t ₅ , the system voltage amplitude is V _abs1 <V _abs <V _abs2 , so the pitch angle command φ ^* is fixed to 15 degrees. . Similarly, during the time t ₃ <t <t ₄ , the system voltage amplitude is V _abs <V _abs1 , so the pitch angle command φ ^* is fixed to 0 [degrees]. By performing such pitch angle control, it is easy to prevent the rotation speed from deviating from the operating range.

The system voltage value (V _GF , V _abs1 , V _abs2, etc.) for switching the pitch angle control method _{depends on} the power system connected to the wind power generation system, the interconnection capacity of the wind power generation system, and the characteristics of the wind power generation system. , Each can be changed. Further, the system voltage level and the fixed pitch angle level when switching the pitch angle control method may be three or more.

  The present invention also includes a secondary excitation type wind power generation system shown in FIG. 3, a permanent magnet generator type wind power generation system shown in FIG. 16, an induction generator type wind power generation system, and a DC excitation synchronous generator type wind power shown in FIG. It can be applied to power generation systems.

  By selecting the pitch angle control method according to the system voltage drop rate as described above, it is possible to suppress overrotation of the rotor even when the instantaneous system voltage drop occurs, and it is possible to resume instantaneous power generation operation immediately after an accident recovery Become. Thereby, since the operation time of a wind power generation system can be lengthened, electric power generation amount increases. In addition, power supply immediately after a system fault and immediately after the system fault is removed can contribute to the stabilization of the entire system.

  A third embodiment of the present invention will be described with reference to FIGS. 21, 22, 23, and 24. FIG. FIG. 21 shows the configuration of a wind power generation system according to this embodiment using a permanent magnet generator. The control system is mainly composed of a high-order windmill controller 25e that controls the movement of the entire windmill and a power converter controller 26e that controls the power converter 28e. The upper wind turbine controller 25e calculates a generated power command and a pitch angle command of the blade 11e from the wind speed measured by the anemometer 24e, the rotational speed ω [rad / sec] of the rotor 1, and the like.

  The power generated by the wind power generation system is controlled by the power converter 28e. The power converter 28e mainly includes a generator-side power converter 281e, a system-side power converter 283e, and a smoothing capacitor 282e. The generator-side power converter 281e and the system-side power converter 283e are configured using semiconductor switching elements such as IGBTs. During normal operation, the generator-side power converter 281e controls the generated power according to the active power command P of the higher wind turbine controller 25e by performing active power control. The generator-side power converter 281e controls the terminal voltage of the permanent magnet generator 23e by simultaneously performing reactive power control. Moreover, the system side power converter 283e supplies the generated power to the power system by performing voltage control of the DC part of the power converter 28e. Moreover, the system side power converter 283e also controls the reactive power output to the power system at the same time.

The power converter controller 26e is supplied with three-phase AC voltage values V _U , V _V , V _W [V], three-phase from the voltage measuring device 291e and the current measuring device 292e installed at the connection point of the wind power generation system. Current values I _U , I _V , I _W [A] are taken in. The power converter controller 26e internally generates a voltage amplitude value V _abs [rms], a current amplitude value I _abs [Arms], an active power (generated power) P [W], and a reactive power Q [ Var] and the like are calculated. Specifically, V _abs [Vrms] and I _abs [Arms] are calculated according to Equations 13 and 14.

The power converter controller 26e always compares the calculated power converter output current amplitude I _abs with predetermined values I _CLR and I _OC inside the power converter controller 26e, and detects an overcurrent phenomenon of the system side power converter 283e. is doing. The predetermined value has a relationship as shown in Formula 15.

  As shown in FIG. 22, system-side power converter 283e is configured with IGBT 2833e, freewheeling diode 2832e, and gate drive circuit 2831e that drives IGBT according to the gate pulse signal received from power converter controller 26e. . If the IGBT 2833e performs a switching operation with a current of a certain value or more flowing, the possibility of breakage increases. Therefore, when detecting the overcurrent, the power converter controller 26e sends a signal for stopping the switching operation to the system-side power converter 283e. The cause of the overcurrent includes a grid fault, a short-circuit fault of the power converter components, or a malfunction of the power converter controller 26e.

FIG. 23 shows the movement of the V _abs detection value and the I _abs detection value when a voltage drop phenomenon due to a system _fault occurs. In FIG. 23, a system fault occurs at time t ₀ , and before that, the system voltage V _abs is normal (V _abs = 100%), and the wind power generation system generates power at the rated power (I _abs = 100%). The voltage drop starts after time t ₀ , so that the current control performance of the grid-side power converter 283e deteriorates and the current value amplitude I _abs begins to increase. When the rate of decrease of the system voltage is fast, the increase of I _abs is fast, and as shown in FIG. 23, the system _fault detection V _abs <90 [%] when the overcurrent detection I _abs > I _OC (time t ₁ ). It occurs earlier than (time t ₂ ). For this reason, it is necessary for the wind power generation system to first switch the control method to a control mode that supports overcurrent, and then switch to the control method that supports system voltage drop.

FIG. 24 shows a flowchart of the operation of the wind power generation system when an overcurrent is detected. Hereinafter, the time series change of the operation method from the overcurrent detection to the restart of the power generation operation will be described.
1) At the time of overcurrent detection When the power converter controller 26e detects an overcurrent, the system side power converter 283e performs a gate block. If the overcurrent is caused by a system voltage drop, the current amplitude _Iabs is rapidly reduced by the gate block. If the current amplitude does not decrease, it is highly possible that the cause of the overcurrent is a failure of the wind power generation system component device. Therefore, the upper wind turbine controller 25e sends an open signal to the circuit breaker 5e, and the wind power generation system Is moved to the stopped state.

  On the other hand, the generator-side power conversion 281e differs in the operation method when detecting the system-side overcurrent depending on the rotational speed of the permanent magnet generator 23e. In the permanent magnet generator 23e, the induced voltage increases as the rotational speed increases. When the induced voltage becomes larger than the output voltage of the generator-side power converter 281e, power control cannot be performed, so control called field weakening operation is performed. This is an operation method in which the generator-side power converter 281e reduces the terminal voltage by controlling the reactive power supplied to the stator of the permanent magnet generator 23e. The relationship between the generator terminal voltage and reactive power during field-weakening operation will be described with reference to FIG. The generator terminal voltage of the permanent magnet generator 23e increases substantially in proportion to the rotational speed when there is no load. For this reason, at a certain rotational speed or higher, the generator terminal voltage becomes larger than the output voltage of the generator-side power converter 281e, making it difficult to control the power of the generator. For this reason, in the operation region where the rotational speed is higher than the predetermined rotational speed ωc [rad / sec], the generator-side power converter 281e supplies reactive power to the generator. The supply of reactive power suppresses an increase in the generator terminal voltage and enables power control by the generator-side power converter 281e even in a region where the rotational speed is high. In FIG. 25, the reactive power is output linearly with respect to the rotational speed, but the reactive power output method of the field weakening operation is not limited to this, and another output method is performed. The same effect can be obtained.

  When an overcurrent occurs in the system-side power converter 283e, the system-side power converter 283e performs a gate block, and thus cannot supply power to the power system. For this reason, in order to suppress the voltage rise of the direct current part of the power converter 28e, the generator-side power converter 281e needs to stop the inflow of the active power from the permanent magnet generator 23e. When the rotational speed is high, the generator-side power converter 281e may have to continue the reactive power supply to the permanent magnet generator 23e. This is because when the rotational speed is increased and the induced voltage of the permanent magnet generator 23e is higher than the DC voltage of the power converter 28e, the generator power is changed via the return diode of the generator-side power converter 281e. This is because energy flows into the direct current section and increases the voltage of the direct current section. In such a case, the terminal voltage can be lowered by the field-weakening operation, and the voltage rise in the DC portion can be suppressed. Therefore, when the rotational speed is high, the generator-side power converter 281e controls the active power of the permanent magnet generator 23e terminal to 0 [W], and at the same time, field-weakening operation by reactive power control is continued. . As a result, an increase in DC voltage during the accident period can be suppressed, and current control and power control on the generator side immediately after the accident recovery can be performed. Note that when the rotational speed of the permanent magnet generator 23e is low and the generator terminal voltage is lower than the DC part voltage of the power converter 28e, the DC part charging does not occur, so the generator side power converter 281e You may block and stop.

  Further, depending on the voltage characteristics of the permanent magnet generator 23e, it is necessary to perform strong field operation. In the permanent magnet generator 23e, the induced voltage decreases as the rotational speed decreases. For this reason, when power control is performed in a region where the rotational speed is low, a large amount of current may be required. When the amount of current exceeds the current capacity limit of the generator-side power converter 281e, power control becomes difficult. FIG. 26 shows the strong field operation. In strong field operation, reactive power is output in a direction in which the generator terminal voltage increases in a region where the rotational speed is low. As a result, even when the rotation speed is low, the amount of current output from the generator-side power converter 281e can be reduced, and power control can be performed.

  If an overcurrent is detected during strong field operation at a low rotation speed, the generator-side power converter 281e controls the effective power of the permanent magnet generator 23e terminal to 0 [W] and continues the strong field operation at the same time. To do. As a result, it is possible to control the voltage of the DC part during the accident, and the current control and power control on the generator side immediately after the accident recovery is facilitated.

  On the other hand, when the overcurrent occurs, the active power P in Formula 10 becomes almost zero by the control of the generator-side power converter 281e, so that the rotational speed of the rotor increases. Therefore, the pitch angle controller 111e controls the pitch angle so that the rotational speed of the rotor is maintained within the operable range as described in the first embodiment.

Note that due to a delay in tracking of the pitch angle control or a rapid increase in the wind speed, there is a case in which the overspeed suppression by the pitch angle control is not sufficient and a phenomenon in which the rotation speed becomes overspeed may occur. When an overspeed state occurs, the wind power generation system stops the power generation operation and shifts to a standby state in order to protect the constituent devices. When shifting to the standby state, the circuit breaker 295e between the permanent magnet generator 23e and the generator-side power converter 281e is opened. Until the circuit breaker 295e is opened, the field-weakening operation on the generator side continues even in the overspeed state. This is for continuing the field-weakening operation to prevent an increase in the voltage of the direct current section due to the inflow of energy from the generator side.
2) over-current power converter controller 26e to removed from the overcurrent decrease, the grid-side power converter 283e of the gate block in the number 13, by performing the calculation of the number 14, the system voltage V _abs and the system current I _abs Continue to observe. When I _abs falls below a predetermined value I _CLR (ie, I _abs <I _CLR ), power converter controller 26e determines that the overcurrent has been removed. At this time, it is determined whether the power system is in a voltage drop state or a normal state according to the magnitude of V _abs , and the subsequent control method is changed.
2-1) Restart when the system voltage is normal When the system voltage amplitude V _abs at the time of overcurrent removal is larger than a predetermined value V _GF , the power converter controller 26e determines that the system voltage is normal. The wind power generation system resumes power generation operation.

The system side power converter 283e releases the gate block and restarts the DC voltage maintenance control and the reactive power control. The generator-side power converter 281e resumes active power control and reactive power control according to the higher-order active power command again. The upper wind turbine controller 25e transmits a pitch angle command during normal power generation operation to the pitch angle controller 111e. Further, the upper wind turbine controller 25e transmits a power command to the power converter controller 26e.
2-2) Restart at the time of system voltage drop The restart method at the time of system voltage fall needs to be changed according to the operation standard of the electric power system which a wind power generation system connects.

  If the system voltage drop is regulated to shut off the wind power generation system from the power system, the wind power generation system continues the gate block operation described in 1), and when the system voltage returns to normal, The power generation operation is resumed in the same procedure as 1). However, when the system voltage drop state has elapsed for a predetermined time or more, the entire wind power generation system is shifted to the standby state.

  If the wind power generation system can be interconnected during the system voltage drop, the gate block of the system side power converter 283e is released, and the DC voltage control is resumed. The generator-side power converter 281e also restarts active power control and reactive power control according to the higher-order active power command. While the system voltage is decreasing, not all of the generated power can be supplied to the power system, so the power generation system tends to over-rotate. Therefore, as described in the first and second embodiments, the pitch angle controller 111e controls the pitch angle so that the rotation speed is maintained within the operable range.

  In addition, the grid interconnection standard may specify the reactive current supply operation of the wind power generation system while the system voltage is decreasing. When the wind power generation system is linked to such a power system, the system-side power converter 283e releases the gate block, and starts DC voltage control and reactive current control without performing reactive power control. The reactive current amount to be output is defined by the grid interconnection standard, and the reactive current amount according to this standard is output. The generator-side power converter also restarts active power control and reactive power control according to the higher-order active power command. While the system voltage is decreasing, not all of the generated power can be supplied to the power system, so the power generation system tends to over-rotate. Therefore, the pitch angle controller 111e controls the pitch angle so that the rotational speed of the rotor is maintained within the operable range.

Depending on the regulations of the power system, there may be a case where active power cannot be input / output to / from the power system while the system voltage is decreasing. When 100% reactive current output is required, only a small amount of active power can be input / output due to device limitations. Equation 16 shows the relationship between the active power and the DC voltage _VDC of the power converter 28e.

V _DC [V] is the DC voltage of the power converter 28e, C [F] is the capacitor capacity of the DC smoothing capacitor 282e, and P _SYS [W] is the effective power output from the system power converter 283e to the power system. , (That is, the generated power of the wind power generation system), P _gen [W] is the effective power entering the DC part of the power converter 28e from the generator-side power converter 281e, and P _LOSS [W] is the energy lost due to loss. . During the grid fault, the grid voltage of the grid-side power converter 283e is low. The generated power P _SYS cannot be controlled to the rated value. For this reason, as explained in the first embodiment, during the normal power generation operation, the system-side power converter 283e controls the voltage of the DC unit, but during the system fault, the generator-side power converter 281e is connected to the DC voltage. Control may be performed.
3) Operation method at the time of system voltage recovery The power converter controller 26e monitors the system voltage amplitude V _abs even when the system voltage is lowered, and if V _abs exceeds a predetermined value, the power converter The controller 26e determines that the system voltage has become normal, and the wind power generation system restarts the power generation operation. That is, the system side power converter 283e performs DC voltage control and reactive power control, and the generator side power converter 281e performs active power control and reactive power control.

  On the other hand, since the system voltage fluctuates when the system voltage is restored, the system-side power converter 283e is likely to cause an overcurrent. When the power converter controller 26e detects an overcurrent, the wind power generation system can resume the power generation operation by performing the same procedure as described above.

  The contents of the invention shown in the present embodiment are not limited to the wind power generation system having the pitch angle control function. For example, the present invention can be applied to a wind power generation system having a stall function that does not have a pitch angle control function.

  By adopting the operation method as described above, it is possible to continue the operation while the wind power generation system is connected to the power system even when an overcurrent is generated in the system-side power converter. Thereby, since the operation time of a wind power generation system can be lengthened, electric power generation amount increases. In addition, power supply immediately after a system failure can contribute to the stabilization of the entire system.

  In addition, although the above invention demonstrated the application to the wind power generation system using a permanent magnet generator, all the wind power generation systems of the structure which has a power converter on the system side similarly (for example, the secondary shown in FIG. 3) The present invention can be applied to all wind power generation systems having excitation type generators, and wind power generation systems having DC excitation type synchronous generators 23c shown in FIG.

  Moreover, the structure shown in each Example mentioned above does not show an effect only by the structure of each Example, It is also possible to combine each Example.

1, 1a rotor 2, 2a nacelle 3, 3a tower 4, 4a, 4b, 4c, 4e interconnection transformer 5, 5a, 5b, 5c, 5e, 284, 295b, 295c, 295e breaker 6, 6a, 6b, 6c , 6e Power system 11, 11a1, 11b, 11c, 11e Blade 12, 12a, 12b, 12c, 12e Hub 21, 21a Shaft 22, 22a Gear 23 Secondary excitation generator 23a, 23b, 23e Permanent magnet generator 23c DC excitation type synchronous generators 24, 24a, 24b, 24c, 24d, 24e Anemometers 25, 25b, 25c, 25d, 25e, 26e Upper wind turbine controllers 26, 26b, 26c, 26d Power converter controllers 27, 27b, 27c, 27d, 27e Encoders 28, 28a, 28b, 28c, 28e Power converter 30a 30b, 30c Auxiliary power supply 41 Step-down transformer 111, 111b, 111c, 111d, 111e Pitch angle controller 280c Excitation devices 281, 281b, 281c, 281e Generator side power converters 282, 282b, 282c, 282e Smoothing capacitors 283, 283b , 283c, 283e System side power converters 291, 291b, 291c, 291e Voltage measuring devices 292, 292b, 292e, 293, 293b, 293c, 293e, 294 Current measuring devices 2501, 2501d Averaging calculator 2502, 2502d Rotational speed command Calculators 2503, 2503d Pitch angle command / power command calculator 2504 Pitch angle command / power command switchers 2506, 2506a, 2506b Pitch angle command calculators 2506a1, 2506b, 25038d, 25 at the time of abnormality 064 Pitch angle command selector 2506b1, 25031, 25031d, 25062 Subtractor 2506b3, 25063 PI controller 2601, 2601a OR calculator 2602, 2602a Voltage amplitude calculator 2603, 2603a, 2604, 2604a, 2606, 2608, 2608a,
2609, 2609a Comparison calculator 2605 Current amplitude calculator 2607, 2607a System frequency detector 2610a, 2611a, 2612a Absolute value calculation circuit 2613a, 2614a, 2615a Diode 2616a Comparator 2617a Variable resistor 2618a Resistor 2619a OR circuit 2831 Gate drive circuit 2832 Freewheeling diode 2833 IGBT
25032, 25032d Pitch angle command calculator 25034, 25034d Power command calculator 25036d, 25061 Limiter 25037d Maximum power command calculator 26001 Abnormality detection calculator 26002 Power calculator 26003 Power control calculator 26004 Rotational speed calculators 26005a, 26005b, 26005c Current detection calculator 26006a, 26006b, 26006c Overcurrent detection circuit

Claims (4)

A blade having a variable pitch angle, a rotor mechanically connected to the blade, and a synchronous generator driven by the rotor;
A generator-side converter that is electrically connected to the synchronous generator and converts the variable frequency generated power output from the synchronous generator into DC power;
A system-side converter electrically connected to the generator-side converter and a power system and converting the DC power into a fixed-frequency AC power, and a control method for a wind power generation system,
When one of the voltage, current and frequency of the power system, or the detected value of the current of the wind power generation system is an abnormal value,
A wind power generation system characterized in that the rotational speed of the rotor is controlled within a certain range by changing the pitch angle of the blade, and the generator-side converter controls the reactive power to the synchronous generator. Control method. In claim 1,
When the detected value of the current of the wind power generation system is an abnormal value,
The system-side converter starts a gate block, and the generator-side converter controls the effective power at the terminal of the synchronous generator to zero. In claim 1,
When the detected value of the current of the wind power generation system is an abnormal value,
The generator-side converter controls the reactive power to the synchronous generator, thereby controlling the terminal voltage of the synchronous generator stator within the operable voltage range of the generator-side converter. To control the wind power generation system. In claim 1,
When the detected value of the current of the wind power generation system is an abnormal value,
Wind power generation characterized in that the generator-side converter controls reactive power to the synchronous generator, thereby controlling a current amount from the synchronous generator to be equal to or less than a current capacity of the generator-side converter. How to control the system.

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