Method for controlling a wind turbine generator system and pitch controller

Abstract

A control method of a wind turbine generator system and a pitch controller are disclosed, the wind turbine generator system comprising a pitch controller, a charger, a super capacitor and a pitch motor, characterized in that the control method comprises: in response to the wind turbine generator system performing a pitch operation, determining whether the voltage of the super capacitor fluctuates; in response to the voltage of the super capacitor fluctuating, determining the charging current of the charger based on the power consumed by the pitch motor; controlling the charger to output the determined charging current to charge the super capacitor and supply power to the pitch motor.

Description

Technical Field

[0001] This disclosure generally relates to the field of wind power generation technology, and more specifically, to a control method and pitch controller for a wind turbine pitch system. Background Technology

[0002] A wind turbine is a device that converts wind energy into electrical energy. Wind energy drives the main shaft, speed increaser, and generator through the rotor, converting them into electrical energy, which is then transmitted to the power grid through grid connection control. The pitch system of a wind turbine plays a crucial role in maximum power point tracking and ensuring the safe shutdown of the wind turbine. The pitch system controls the rotor speed (i.e., the wind turbine speed) by controlling the blade angle, thereby controlling the output power of the wind turbine and enabling the safe shutdown of the wind turbine through aerodynamic braking.

[0003] In a pitch control system, the supercapacitor serves as a backup power source: when a grid fault occurs (such as a power outage or low-voltage ride-through), the pitch control system needs to be powered by the backup power source to perform pitch recovery operations. To prevent major accidents, strict monitoring of the backup power source's performance is crucial. Abnormal voltage values ​​will occur when the supercapacitor's casing is damaged, the electrodes deteriorate, the wiring becomes loose, or the electrolyte decomposes.

[0004] For pitch control systems, since the supercapacitor is directly connected to the pitch driver as a backup power source, an anomaly in the supercapacitor causing voltage fluctuations will increase the current during charging and discharging. This current will be injected into the pitch driver, causing a malfunction in its inverter unit. Once the pitch driver malfunctions, it will shut down and be unable to drive the pitch motor, leading to blade jamming—the wind turbine blades failing to retract to a safe position (e.g., 88°). If the wind turbine blades cannot retract to a safe position, the wind force will prevent the turbine's speed from decreasing, potentially causing overspeeding or even runaway. With the increasing number of wind turbines, batch failures, especially those affecting turbine safety, will directly impact the development of wind power companies and are therefore receiving increasing attention. In this context, numerous detection methods have emerged for blade jamming, major component reliability testing, and grid connection safety testing. However, an effective detection method specifically for anomalies caused by voltage fluctuations in supercapacitors is still lacking. Summary of the Invention

[0005] The embodiments of this disclosure provide a control method and pitch controller for a wind turbine generator pitch system. After the voltage of the supercapacitor fluctuates, the charger can be controlled to directly provide energy to the pitch motor, thereby reducing the drastic voltage fluctuation of the supercapacitor and preventing blade jamming caused by supercapacitor abnormalities, thus protecting the safety of the wind turbine generator.

[0006] In one general aspect, a control method for a wind turbine pitch system is provided, the wind turbine pitch system including a pitch controller, a charger, a supercapacitor, and a pitch motor, the control method including: in response to the wind turbine pitch system performing a pitch operation, determining whether the voltage of the supercapacitor fluctuates; in response to the voltage fluctuation of the supercapacitor, determining the charging current of the charger based on the power consumed by the pitch motor; controlling the charger to output the determined charging current to charge the supercapacitor, while simultaneously supplying power to the pitch motor.

[0007] Optionally, the step of determining whether the voltage of the supercapacitor fluctuates includes: calculating the voltage variance of the supercapacitor over a predetermined time period and determining the minimum voltage of the supercapacitor; and determining whether the voltage of the supercapacitor fluctuates based on the variance and the minimum voltage.

[0008] Optionally, the step of determining whether the voltage of the supercapacitor fluctuates based on the variance value and the minimum value includes: determining that the voltage of the supercapacitor fluctuates in response to the variance value being greater than a first preset threshold and the minimum value being less than a second preset threshold; wherein the second preset threshold is less than the rated voltage of the supercapacitor.

[0009] Optionally, the step of determining the charging current of the charger based on the power consumed by the pitch motor includes: determining the power consumed by the pitch motor based on the torque and speed of the pitch motor, or based on the voltage and current of the pitch motor; and determining the charging current of the charger based on the power consumed by the pitch motor and the charging voltage of the charger, based on the law of conservation of energy.

[0010] Optionally, based on energy conservation, the step of determining the charging current of the charger using the power consumed by the pitch motor and the charging voltage of the charger includes: determining the product of the power consumed by the pitch motor and a first overcharge protection coefficient, wherein the first overvoltage protection coefficient is greater than 0 and less than 1; and determining the quotient of the product and the charging voltage of the charger as the charging current of the charger.

[0011] Optionally, the control method further includes: determining whether the charging current of the charger is within a preset normal current range; and in response to the charging current of the charger being within the preset normal current range, performing the step of controlling the charger to output a determined charging current.

[0012] Optionally, the control method further includes: monitoring the voltage of the supercapacitor; and controlling the charger to pause outputting a determined charging current in response to the voltage of the supercapacitor being greater than a third preset threshold.

[0013] Optionally, the control method further includes: in response to the voltage of the supercapacitor being less than a fourth preset threshold, controlling the charger to resume outputting a determined charging current, or returning to the step of determining whether the voltage of the supercapacitor has fluctuated, wherein the third preset threshold is the product of the rated voltage of the supercapacitor and the second overvoltage protection coefficient, the fourth preset threshold is the rated voltage of the supercapacitor, and the second overvoltage protection coefficient is greater than 1.

[0014] In another general aspect, a computer-readable storage medium is provided that stores a computer program, which, when executed by a processor, implements the control method described above.

[0015] In another general aspect, a pitch controller is provided, the pitch controller comprising: a processor; and a memory storing a computer program that, when executed by the processor, implements the control method as described above.

[0016] In another general aspect, a wind turbine generator set is provided, the wind turbine generator set including the pitch controller as described above.

[0017] According to the control method and pitch controller of the wind turbine pitch system of the present disclosure, after the voltage of the supercapacitor fluctuates, the charger can be controlled to directly provide energy to the pitch motor by controlling the charging current of the charger, thereby reducing the energy consumption of the supercapacitor, reducing the drastic voltage fluctuation of the supercapacitor, and preventing blade jamming caused by supercapacitor abnormality, thus protecting the safety of the wind turbine.

[0018] According to the control method and pitch controller of the wind turbine pitch system of the present disclosure, while providing energy to the pitch motor, the supercapacitor is charged, which can avoid the supercapacitor from being over-voltaged and further damaged, and therefore will not cause any unexpected safety hazards. Attached Figure Description

[0019] The above and other objects and features of the embodiments of this disclosure will become clearer from the following description taken in conjunction with the accompanying drawings illustrating the embodiments, wherein:

[0020] Figure 1 This is a circuit topology diagram showing the pitch system of a wind turbine generator set;

[0021] Figure 2 It is a graph showing the voltage fluctuation of a supercapacitor;

[0022] Figure 3This is a flowchart illustrating a control method for a wind turbine pitch system according to an embodiment of the present disclosure;

[0023] Figure 4 This is a block diagram illustrating a pitch controller according to an embodiment of the present disclosure. Detailed Implementation

[0024] The following detailed embodiments are provided to aid the reader in gaining a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatus, and / or systems described herein will become apparent upon understanding this disclosure. For example, the order of operations described herein is merely illustrative and is not limited to those orders set forth herein, but may be changed as will become clear upon understanding this disclosure, except for operations that must occur in a specific order. Furthermore, for clarity and conciseness, descriptions of features known in the art may be omitted.

[0025] Currently, the common approach to handling supercapacitor malfunctions is to replace the faulty supercapacitor. This method is reactive, meaning that intervention only occurs after the supercapacitor malfunctions, triggering a fault or even causing blade jamming. However, blade jamming is precisely the greatest safety threat to wind turbine generators. Furthermore, temporarily halting blade pitch control when a supercapacitor malfunction is detected also carries significant risks. This is because the blades corresponding to the malfunctioning supercapacitor may be random; actively stopping pitch control on that blade could lead to voltage fluctuations in more than one blade. If two or three blades simultaneously stop pitch control (or retract their pitch), it poses a significant safety hazard to the wind turbine generator. Therefore, this disclosure proposes a control method and pitch controller for a wind turbine generator pitch system. When supercapacitor voltage fluctuates, the controller can directly supply energy to the pitch motor via a charger, reducing drastic voltage fluctuations in the supercapacitor, preventing blade jamming due to supercapacitor malfunctions, and protecting the safety of the wind turbine generator.

[0026] Figure 1 This is a circuit topology diagram showing the pitch system of a wind turbine generator set.

[0027] Reference Figure 1The pitch system 100 may include a charger 102, a supercapacitor 103, a pitch driver 104, a pitch motor 105, and a pitch controller 106. The charger 102 uses the grid as its power source to charge the supercapacitor 103. The supercapacitor 103 supplies power to the pitch driver 104, which, under the control of the pitch controller 106, drives the pitch motor 105. An encoder is installed on the pitch motor 105 for the pitch controller 106 to acquire blade angle data. The pitch controller 106 communicates with the charger 102 via CANOpen for data exchange and to control the output switching of the charger 102. 107 indicates the wire connecting the charger 102 and the supercapacitor 103, and 108 indicates the wire connecting the pitch controller 106 and the pitch driver 104. The pitch controller 106 also communicates and exchanges data with the main control system of the wind turbine generator.

[0028] When the power grid is operating normally, the charger 102 uses the grid voltage to charge the supercapacitor 103, maintaining the voltage of the supercapacitor at the rated voltage, and providing power for the operation of the pitch motor 105. When the power grid fails, the supercapacitor 103 serves as a backup power source to provide power for the operation of the pitch motor 105.

[0029] The working principle and control method of charger 102 are described below. Charger 102 monitors the voltage value of supercapacitor 103 in real time and compares it with the preset voltage value. When the voltage value of supercapacitor 103 drops due to the energy consumption of pitch motor 105, charger 102 starts charging supercapacitor 103. The charging process is PID controlled, that is, the input is the preset voltage value of supercapacitor 103, the feedback is the actual voltage value of supercapacitor 103, and the output is the magnitude (amplitude) of the charging current.

[0030] Charger 102 is typically controlled by a PI controller, meaning the integral coefficient Kd = 0. Taking incremental PI as an example, the calculation formula for PI control is:

[0031] I(k)=Kp(e(k)-e(k-1))+Ki(e(k)+0*(e(k)-2e(k-1)+e(k-2)) (1)

[0032] Where e(k) represents the current deviation (i.e., the deviation between the actual voltage value and the preset voltage value), e(k-1) represents the previous deviation, and e(k-2) represents the deviation before that; I(k) represents the current output value of the PID controller.

[0033] The charger 102 operates by detecting only the voltage of the supercapacitor 103. It only starts working when the voltage of the supercapacitor 103 drops. Therefore, during the operation of the pitch motor 105, the voltage of the supercapacitor 103 drops first due to the energy consumption of the pitch motor 105. If the supercapacitor 103 malfunctions at this point, the voltage drop will accelerate. After the voltage drops, the charger 102 begins charging the supercapacitor 103. Once charging begins, the voltage of the supercapacitor 103 immediately and rapidly increases again. This repeated process causes drastic fluctuations in the voltage of the supercapacitor 103.

[0034] Figure 2 This is a graph showing the voltage fluctuations of a supercapacitor.

[0035] like Figure 2 As shown, the horizontal axis represents time, and the vertical axis represents voltage amplitude. After the supercapacitor malfunctions, its voltage fluctuates. From... Figure 2 As can be seen, the voltage value of the supercapacitor corresponding to curve 201 fluctuated at a high frequency, with fluctuations exceeding 20V. Furthermore, the minimum voltage of the supercapacitor decreased by approximately 10V compared to its rated voltage (the values ​​corresponding to curves 202 and 203), a significant drop (under normal circumstances, the voltage drop of the supercapacitor during feathering is typically only 0.4–0.5V). Simultaneously, the high-frequency fluctuations in curve 201 caused the pitch drive to malfunction, resulting in blade jamming. This is because, according to the capacitance formula C = It / ΔU, the current I is proportional to the voltage change ΔU. Therefore, voltage fluctuations resulted in a large current being injected into the pitch drive, leading to abnormal operation of the pitch drive.

[0036] This disclosure is based on Figure 1 The circuit topology and working principle of the pitch system are shown. A control method for the pitch system of a wind turbine generator is proposed. The basic principle is to take advantage of the parallel connection of the charger, pitch driver and supercapacitor. During the operation of the pitch system (especially the pitch retraction process), the charger directly provides power to the pitch motor, reducing the power consumption of the supercapacitor.

[0037] The core principle of the control method for the wind turbine pitch system according to the embodiments of this disclosure is that: the wind turbine pitch system performs pitch operation, and calculates the energy consumption of the pitch motor by utilizing the topology of the pitch system and the principle of energy conservation, and calculates the energy that the charger needs to provide to the pitch motor.

[0038] Specifically, assuming the pitch speed is v, the gear ratio of the pitch system is a, the pitch motor speed is n = v * a, the time required from the start of pitch control to completion (e.g., the blade position reaches 89°) is t, and the pitch motor torque is N, the relationship between the pitch motor torque N, speed n, and power p can be derived from N = 9550 * p / n:

[0039] p=N*v*a / 9.54 (2)

[0040] Then, during the pitch operation time t, the mechanical work W1 done by the pitch motor is:

[0041] W1=p*t / b / c (3)

[0042] Where b is the pitch motor power factor, which is set according to the pitch motor parameters, and is generally 91%, but not limited to this; c is the pitch motor efficiency, which is also set according to the pitch motor parameters, for example, it can be 91%, but not limited to this.

[0043] During pitch control, in order to provide energy for W1, the charger needs to output current that meets the following requirements:

[0044] W1=U*I*t (4)

[0045] Where U represents the charging voltage of the charger; I is the charging current of the charger. The charging voltage U is a constant value, equal to the rated voltage of the supercapacitor. The charging current is no longer controlled by the PID controller inside the charger, but is calculated by the pitch controller based on the energy consumption of the pitch motor.

[0046] Specifically, considering the power factor and efficiency of the pitch motor, in practical control, only the mechanical energy of the pitch motor can be calculated, and the charging current of the charger can be calculated based on this mechanical energy. That is, W2 = p*t = U*I*t. Meanwhile, since time t is constant, the charging current of the charger can be calculated using the following equation:

[0047] N*v*a / 9.54=U*I (5)

[0048] For example, assuming the pitch control unit uses six 16V / 500F supercapacitor modules connected in series, with a capacitance of 500 / 6 = 83.3F, a rated voltage of 85V for the supercapacitors, a charging voltage of 85V for the charger, a pitch speed of 2° / second, and a transmission ratio of 2014.64, the corresponding pitch motor speed is n = ((2*60) / 360)*2014.64 = 671.54rpm, and the pitch motor torque is 20Nm. Thus, according to equation (5), the charging current of the charger is calculated as I = 20Nm*671.54rpm / 9.54 / 85V = 16.56A. Typically, the maximum charging current of the charger is 90A, and 16.56A is much smaller than 90A. Therefore, the charging current of the charger meets the design requirements and can provide the energy required for the operation of the pitch motor.

[0049] Specifically, if the pitch drive cannot acquire the pitch motor torque value, the charger current can be directly calculated using the energy conservation formula, i.e.:

[0050] U1*I1=U*I (6)

[0051] Wherein, U1 represents the voltage of the pitch motor, and I1 represents the current of the pitch motor. Since the current value of the pitch motor fluctuates little during the pitch control process, the control method of the wind turbine pitch system according to the embodiments of this disclosure is simple, reliable, and easy to implement.

[0052] The following reference Figure 3 A detailed description of a control method for a wind turbine pitch system according to embodiments of the present disclosure.

[0053] Figure 3 This is a flowchart illustrating a control method for a wind turbine pitch system according to an embodiment of the present disclosure. As described above, the wind turbine pitch system includes at least a pitch controller, a charger, a supercapacitor, and a pitch motor. The control method for the wind turbine pitch system can be executed by the pitch controller, but the present disclosure is not limited thereto. For example, the control method for the wind turbine pitch system can be executed by the main control system of the wind turbine.

[0054] Reference Figure 3In step S301, in response to the wind turbine generator pitch system performing pitch operation, it can be determined whether the voltage of the supercapacitor fluctuates. Specifically, the voltage variance of the supercapacitor within a predetermined time period can be calculated first, and the minimum voltage value of the supercapacitor can be determined. Then, based on the calculated variance and the determined minimum value, it can be determined whether the voltage of the supercapacitor fluctuates. For example, if the calculated variance is greater than a first preset threshold and the determined minimum value is less than a second preset threshold, it can be determined that the voltage of the supercapacitor fluctuates. Here, the second preset threshold is less than the rated voltage of the supercapacitor. For example, the predetermined time period can be 100–500 ms, the first preset threshold can be set to 0.2, and the second preset threshold can be less than the rated voltage of the supercapacitor (3V), but this disclosure is not limited thereto. Those skilled in the art can reasonably set the length of the predetermined time period and the first and second preset thresholds according to the actual situation.

[0055] Next, in step S302, in response to voltage fluctuations in the supercapacitor, the charging current of the charger can be determined based on the power consumed by the pitch motor. Specifically, the power consumed by the pitch motor can first be determined based on its torque and speed, or its voltage and current. Then, based on energy conservation, the charging current of the charger can be determined using the power consumed by the pitch motor and the charging voltage of the charger. For example, the power consumed by the pitch motor can be determined as N*v*a / 9.54 based on its torque N and speed n, where a is the transmission ratio of the pitch system. Another example is that the power consumed by the pitch motor can be determined as U1*I1 based on its voltage U1 and current I1. Energy conservation means that the power consumed by the pitch motor is equal to the output power of the charger, i.e., N*v*a / 9.54=U*I, or U1*I1=U*I, where U represents the charging voltage (rated voltage) of the charger, and I represents the charging current of the charger.

[0056] According to embodiments of this disclosure, to prevent overvoltage of the supercapacitor, when determining the charging current of the charger, the product of the power consumed by the pitch motor and a first overcharge protection coefficient can be determined first. Then, the quotient of this product and the charging voltage of the charger can be determined as the charging current of the charger. Here, the first overvoltage protection coefficient can be greater than 0 and less than 1. For example, the first overvoltage protection coefficient can be 0.9 to 0.98, but is not limited thereto.

[0057] In step S303, the charger can be controlled to output a determined charging current to charge the supercapacitor and simultaneously supply power to the pitch motor. According to embodiments of this disclosure, to avoid an excessively large determined charging current, it is first determined whether the charger's charging current is within a preset normal current range, and step S303 is executed in response to the charger's charging current being within the preset normal current range. For example, the normal current range can be 0–90A, but is not limited to this.

[0058] Optionally, to prevent overvoltage of the supercapacitor, the voltage of the supercapacitor can be monitored while the charger is charging it. If the supercapacitor voltage exceeds a third preset threshold, the charger can pause outputting a predetermined charging current. Thereafter, the supercapacitor voltage is continuously monitored. If the supercapacitor voltage falls below a fourth preset threshold, the charger can resume outputting the predetermined charging current, or return to step S301 to re-determine whether the supercapacitor voltage has fluctuated. Here, the third preset threshold is the product of the supercapacitor's rated voltage and a second overvoltage protection coefficient, the fourth preset threshold is the supercapacitor's rated voltage, and the second overvoltage protection coefficient is greater than 1. For example, the second overvoltage protection coefficient can be 1.1, but is not limited to this.

[0059] According to the control method of the wind turbine pitch system of the present disclosure, after the voltage of the supercapacitor fluctuates, the charging current of the charger can be controlled to enable the charger to directly provide energy to the pitch motor, thereby reducing the energy consumption of the supercapacitor, thereby reducing the drastic voltage fluctuation of the supercapacitor, and thus preventing blade jamming caused by supercapacitor abnormality, and protecting the safety of the wind turbine.

[0060] Figure 4 This is a block diagram illustrating a pitch controller according to an embodiment of the present disclosure.

[0061] Reference Figure 4 The pitch controller 400 according to embodiments of the present disclosure may include a processor 410 and a memory 420. The processor 410 may include (but is not limited to) a central processing unit (CPU), a digital signal processor (DSP), a microcomputer, a field-programmable gate array (FPGA), a system-on-a-chip (SoC), a microprocessor, an application-specific integrated circuit (ASIC), etc. The memory 420 may store computer programs to be executed by the processor 410. The memory 420 may include high-speed random access memory and / or non-volatile computer-readable storage media. When the processor 410 executes the computer program stored in the memory 420, the wind-storage combined frequency modulation method described above can be implemented.

[0062] Optionally, the pitch controller 400 can communicate with various other components in the wind turbine generator via wired or wireless communication, and can also communicate with other devices in the wind farm via wired or wireless communication. Furthermore, the pitch controller 400 can communicate with devices outside the wind farm via wired or wireless communication.

[0063] The control method for a wind turbine pitch system according to embodiments of the present disclosure can be programmed into a computer program and stored on a computer-readable storage medium. When the computer program is executed by a processor, the control method for the wind turbine pitch system as described above can be implemented. Examples of computer-readable storage media include: read-only memory (ROM), random access programmable read-only memory (PROM), electrically erasable programmable read-only memory (EEPROM), random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), flash memory, non-volatile memory, CD-ROM, CD-R, CD+R, CD-RW, CD+RW, DVD-ROM, DVD-R, DVD+R, DVD-RW, DVD+RW, DVD-RAM, BD-ROM, BD-R, BD-R LTH, BD-RE, Blu-ray or optical disc storage, hard disk drive (HDD), solid-state drive (SSD), card storage (such as multimedia cards, secure digital (SD) cards, or ultra-fast digital (XD) cards), magnetic tape, floppy disk, magneto-optical data storage device, optical data storage device, hard disk, solid-state drive, and any other device configured to store a computer program and any associated data, data files, and data structures in a non-transitory manner and to provide the computer program and any associated data, data files, and data structures to a processor or computer so that the processor or computer can execute the computer program. In one example, the computer program and any associated data, data files, and data structures are distributed across a networked computer system, such that the computer program and any associated data, data files, and data structures are stored, accessed, and executed in a distributed manner through one or more processors or computers.

[0064] According to the control method and pitch controller of the wind turbine pitch system of the present disclosure, after the voltage of the supercapacitor fluctuates, the charger can be controlled to directly provide energy to the pitch motor by controlling the charging current of the charger, thereby reducing the energy consumption of the supercapacitor, reducing the drastic voltage fluctuation of the supercapacitor, and preventing blade jamming caused by supercapacitor abnormality, thus protecting the safety of the wind turbine.

[0065] According to the control method and pitch controller of the wind turbine pitch system of the present disclosure, while providing energy to the pitch motor, the supercapacitor is charged, which can avoid the supercapacitor from being over-voltaged and further damaged, and therefore will not cause any unexpected safety hazards.

[0066] While some embodiments of this disclosure have been shown and described, those skilled in the art will understand that modifications may be made to these embodiments without departing from the principles and spirit of this disclosure, which are defined by the claims and their equivalents.

Claims

1. A control method for a wind turbine generator pitch system, wherein the wind turbine generator pitch system includes a pitch controller, a charger, a supercapacitor, and a pitch motor, characterized in that, The control method includes: In response to the wind turbine pitch system performing pitch operation, the voltage variance of the supercapacitor is calculated within a predetermined time period, and the minimum voltage of the supercapacitor is determined. In response to the variance value being greater than a first preset threshold and the minimum value being less than a second preset threshold, it is determined that the voltage of the supercapacitor has fluctuated; wherein the second preset threshold is less than the rated voltage of the supercapacitor. In response to voltage fluctuations in the supercapacitor, the charging current of the charger is determined based on the power consumed by the pitch motor. The charger outputs a determined charging current to charge the supercapacitor and simultaneously power the pitch motor.

2. The control method for the pitch control system of a wind turbine generator as described in claim 1, characterized in that, The steps for determining the charger's charging current based on the power consumed by the pitch motor include: Determine the power consumed by the pitch motor based on its torque and speed, or based on its voltage and current. Based on the law of conservation of energy, the charging current of the charger is determined by using the power consumed by the pitch motor and the charging voltage of the charger.

3. The control method for the pitch control system of a wind turbine generator as described in claim 2, characterized in that, Based on the law of conservation of energy, the steps for determining the charging current of the charger using the power consumed by the pitch motor and the charging voltage of the charger include: Determine the product of the power consumed by the pitch motor and the first overvoltage protection coefficient, wherein the first overvoltage protection coefficient is greater than 0 and less than 1; The quotient of the product and the charger's charging voltage is determined as the charger's charging current.

4. The control method for the pitch control system of a wind turbine generator as described in claim 2, characterized in that, The control method further includes: Determine whether the charger's charging current is within the preset normal current range; In response to the charger's charging current being within a preset normal current range, the step of controlling the charger to output a determined charging current is executed.

5. The control method for the pitch control system of a wind turbine generator as described in claim 1, characterized in that, The control method further includes: Monitor the voltage of the supercapacitor; In response to the voltage of the supercapacitor exceeding a third preset threshold, the charger is controlled to pause outputting a predetermined charging current.

6. The control method for the pitch control system of a wind turbine generator set as described in claim 5, characterized in that, The control method further includes: In response to the supercapacitor's voltage falling below a fourth preset threshold, the charger is controlled to resume outputting a predetermined charging current, or the process returns to the step of determining whether the supercapacitor's voltage has fluctuated. The third preset threshold is the product of the supercapacitor's rated voltage and the second overvoltage protection coefficient, and the fourth preset threshold is the supercapacitor's rated voltage, wherein the second overvoltage protection coefficient is greater than 1.

7. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the control method for the wind turbine pitch system as described in any one of claims 1 to 6.

8. A pitch controller, characterized in that, The pitch controller includes: processor; and A memory storing a computer program that, when executed by a processor, implements the control method for the wind turbine pitch system as described in any one of claims 1 to 6.

9. A wind turbine generator set, characterized in that, The wind turbine generator set includes the pitch controller as described in claim 8.

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