Pitch control method and pitch controller for wind turbine generator set

Abstract

Disclosed are a pitch control method and pitch controller for a wind turbine generator set. The pitch control method includes: discretizing a given pitch speed based on a direction of change of the given pitch speed; determining a fluctuation frequency of the given pitch speed in response to a change in the direction of change of the given pitch speed; calculating an average of a maximum value and a minimum value of the given pitch speed during a predetermined time period in response to the fluctuation frequency of the given pitch speed being greater than a predetermined threshold; and performing a pitch control operation using the calculated average value as the current given pitch control speed, wherein the predetermined time period is the period from the moment when the direction of change of the given pitch speed last changed to the moment when the direction of change of the given pitch speed this time changes.

Description

Technical Field

[0001] The present disclosure generally relates to the field of wind power generation technology, and more specifically, to a pitch control method and a pitch controller for a wind turbine generator set. Background Art

[0002] With the increasing capacity of wind turbines, variable pitch control has become the mainstream control method for wind turbines. The generator is a key device in a wind turbine that converts wind energy into electrical energy. Its operational stability not only directly affects the quality and efficiency of the output power, but also the performance of the entire wind power conversion system and the complexity of the device structure.

[0003] The pitch control system fully accepts speed control commands from the master controller during the pitch control process to achieve the pitch control function. However, when the given pitch speed fluctuates abnormally, the pitch motor's current is highest at the moment of starting and stopping. Therefore, the frequent reversing and starting of the pitch motor will cause the pitch motor to heat up too quickly, with the maximum temperature exceeding 150°C.

[0004] On the other hand, if the given pitch speed fluctuates too frequently, for example, exceeding 10Hz, the pitch drive may become jammed due to excessive commutation frequency. Because the given pitch speed is sent simultaneously to the three pitch controllers by the master controller, there is a risk of all three blades jamming simultaneously. This could seriously impact the safety of the wind turbine.

[0005] In addition to abnormal fluctuations in control, since the pitch control of the wind turbine is based on PID control of the speed, that is, the input is the target speed and the actual speed, and the output is the pitch speed, fluctuations in the speed measurement value will also cause fluctuations in the given pitch speed.

[0006] Currently, traditional average filtering methods or variance methods are generally used to handle fluctuations in a given pitch speed. However, because the data is averaged after filtering, it is impossible to detect the changing state of the data. On the other hand, its detection results depend on the amplitude and frequency of the data fluctuations. Different frequencies and amplitudes will lead to different detection parameters. During the operation of wind turbines, the operating conditions are random and unstable, making it difficult to determine reasonable parameters to protect the safety of the wind turbine. Furthermore, the variance method can only detect whether the data deviates from the normal value, but cannot detect the fluctuation trend of the data, and the variance value cannot filter out problems caused by accidental jumps.

[0007] Another drawback of the traditional average filtering method is that it typically detects fluctuations in the given pitch speed and triggers a fault, causing a direct shutdown. This can significantly impact wind turbine power generation. To ensure continued operation, the original given pitch speed must be properly processed. However, direct averaging can only reduce the amplitude of data fluctuations, not completely eliminate them. Setting the average parameter too high can also affect the control accuracy of the pitch system.

[0008] If the value before the given pitch speed fluctuation is used or a speed of 0 is output after fluctuation is detected, then due to the uncertainty of the changing trend of the given pitch speed during the pitch change process, locking it at a certain speed and outputting it still poses a significant safety risk to the wind turbine. In addition, since the given pitch speed is a continuous analog quantity, the frequency value is usually obtained by fast Fourier transform (FFT) during frequency detection. However, the pitch controller only has basic arithmetic and logical operations and cannot implement FFT. If discrete quantity processing is performed with 0 as the dividing point, when the given pitch speed is not 0 but fluctuates, the data fluctuation cannot be detected.

[0009] In addition, the problem faced by using only the direction of change of a given pitch speed as a discrete quantity is that the detection frequency generally requires a certain period, such as calculating once every 400ms. During this process, the average value is output only once every 400ms, which means that during this period, the pitch motor is in a stopped state for 400ms. Since the wind speed is transient, this control method cannot be directly applied to the pitch control of wind turbines. Furthermore, directly using the function curve to detect whether the curve is a normal fluctuation is very complicated. It is necessary to detect various data such as period, amplitude and even phase. Since the data is always changing, the sine function needs to be continuously adjusted, making it difficult to ensure detection accuracy. Summary of the Invention

[0010] Therefore, it is crucial to protect the safety of the wind turbine to detect the received given pitch speed inside the pitch controller and process the given pitch speed effectively and reasonably so that the process of controlling the pitch does not affect the operation of the wind turbine.

[0011] In a general aspect, a pitch control method for a wind turbine generator set is provided, the pitch control method comprising: discretizing a given pitch speed based on a direction of change of a given pitch speed; determining a fluctuation frequency of the given pitch speed in response to a change in the direction of change of the given pitch speed; calculating an average value of a maximum value and a minimum value of the given pitch speed during a predetermined time period in response to the fluctuation frequency of the given pitch speed being greater than a predetermined threshold; and performing a pitch operation using the calculated average value as a current given pitch control speed, wherein the predetermined time period refers to a time period from the moment when the direction of change of the given pitch speed last changed to the moment when the direction of change of the given pitch speed this time changes.

[0012] Optionally, in response to the rate of change of the given pitch speed being a positive value, the direction of change of the given pitch speed is determined to be a first direction, and in response to the rate of change of the given pitch speed being a negative value, the direction of change of the given pitch speed is determined to be a second direction, wherein each time the rate of change of the given pitch speed changes between positive and negative values, it is determined that the direction of change of the given pitch speed has changed.

[0013] Optionally, based on the direction of change of the given pitch speed, the step of discretizing the given pitch speed includes: based on the direction of change of the given pitch speed being a first direction, setting the current given pitch speed to a first discrete value; based on the direction of change of the given pitch speed being a second direction, setting the current given pitch speed to a second discrete value.

[0014] Optionally, in response to a change in the direction of change of the given pitch speed, determining the fluctuation frequency of the given pitch speed comprises: determining the fluctuation frequency of the given pitch speed based on the number of first discrete values or the number of second discrete values during a predetermined detection period.

[0015] Optionally, the pitch control method also includes: continuously reading a given pitch speed; comparing the maximum value and the minimum value of the current given pitch speed and the given pitch speeds that have been read; in response to the current given pitch speed being greater than the maximum value of the given pitch speed, recording the current given pitch speed as the maximum value of the given pitch speed; in response to the current given pitch speed being less than the minimum value of the given pitch speed, recording the current given pitch speed as the minimum value of the given pitch speed, wherein, whenever the direction of change of the given pitch speed changes, the maximum value of the given pitch speed is set to a first initial value, and the minimum value of the given pitch speed is set to a second initial value, wherein the first initial value is less than the second initial value.

[0016] Optionally, the step of using the calculated average value as the current given pitch control speed to perform the pitch operation includes: performing a sliding average filtering on the calculated average value, and using the filtered average value as the current given pitch control speed to perform the pitch operation, wherein the parameter of the sliding average filtering is a positive integer less than or equal to 5.

[0017] Optionally, the pitch control method further includes: in response to a fluctuation frequency of the given pitch speed being less than or equal to a predetermined threshold, performing a pitch operation according to the given pitch speed at a moment when a change direction of the given pitch speed changes.

[0018] In another general aspect, a computer-readable storage medium storing a computer program is provided, which, when executed by a processor, implements the pitch control method described above.

[0019] In another general aspect, a pitch controller is provided, comprising: a processor; and a memory storing a computer program, wherein when the computer program is executed by the processor, the pitch control method described above is implemented.

[0020] In another general aspect, a wind turbine generator set is provided, comprising the pitch controller as described above.

[0021] The pitch control method and pitch controller for a wind turbine generator set according to the embodiments of the present disclosure can address the problems of difficulty in detecting the fluctuation frequency of a given pitch speed and the inability of the current given pitch speed to follow the overall speed change trend. The pitch control method and pitch controller can also address the following issues: In traditional mean filtering methods, a small filter window results in poor filtering effectiveness, while a long filter window can cause the given pitch speed to remain unchanged for extended periods, impacting the safe operation of the wind turbine generator set. The pitch control method and pitch controller can also address the problem of only detecting fluctuations in the given pitch speed and directly triggering a fault shutdown upon detection, resulting in power generation loss. The pitch control method and pitch controller can effectively capture the fluctuation characteristics and trends of the given pitch speed, thereby applying them to the pitch control of a wind turbine generator set. The pitch control method and pitch controller can also effectively address the shortcomings of methods that detect fluctuation slope and number of jumps, such as single jumps, variable periods, and variable amplitudes, and can automatically and intelligently determine the centerline of the fluctuating given pitch speed.

[0022] In addition, the pitch control method and pitch controller of the wind turbine generator set according to the embodiment of the present disclosure can effectively detect when the given pitch speed of the wind turbine generator set fluctuates, and ensure the operational safety of the wind turbine and the accuracy of pitch control without shutting down the wind turbine generator set. In other words, the pitch control method and pitch controller of the wind turbine generator set according to the embodiment of the present disclosure can avoid the wind turbine generator set from triggering faults and avoiding protective shutdowns of the wind turbine generator set, reducing the operational risk and failure rate of the wind turbine generator set, which is of great significance for improving the revenue of the wind farm, especially avoiding the occurrence of serious accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and other objects and features of the embodiments of the present disclosure will become more apparent through the following description in conjunction with the accompanying drawings showing the embodiments, in which:

[0024] Figure 1 is a graph illustrating a first example of fluctuations in a given pitch speed;

[0025] Figure 2 is a graph illustrating a second example of fluctuations in a given pitch speed;

[0026] Figure 3 is a graph illustrating a third example of fluctuations in a given pitch speed;

[0027] Figure 4 is a graph illustrating a fourth example of fluctuations in a given pitch speed;

[0028] Figure 5 is a schematic diagram illustrating a method of detecting a fluctuation frequency in the prior art;

[0029] Figure 6 is a flow chart illustrating a pitch control method of a wind turbine generator set according to an embodiment of the present disclosure;

[0030] Figure 7 is a diagram illustrating an example of discretizing a given pitch speed according to an embodiment of the present disclosure;

[0031] Figure 8 is a block diagram illustrating a pitch controller according to an embodiment of the present disclosure;

[0032] Figure 9 3 is a schematic diagram illustrating the application effect of the pitch control method of a wind turbine generator set according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0033] The following detailed description is provided to help the reader gain a comprehensive understanding of the methods, devices and / or systems described herein. However, various changes, modifications and equivalents of the methods, devices and / or systems described herein will be clear after understanding the disclosure of the present application. For example, the order of operations described herein is merely an example and is not limited to those orders set forth herein, but can be changed as will be clear after understanding the disclosure of the present application, except for operations that must occur in a specific order. In addition, for greater clarity and conciseness, descriptions of features known in the art may be omitted.

[0034] The features described herein can be implemented in different forms and should not be construed as limited to the examples described herein. Rather, the examples described herein are provided to illustrate only some of the many possible ways to implement the methods, devices, and / or systems described herein, which will become clear after understanding the disclosure of this application.

[0035] As used herein, the term "and / or" includes any one of the associated listed items and any combination of any two or more.

[0036] Although terms such as "first," "second," and "third" may be used herein to describe various members, components, regions, layers, or portions, these members, components, regions, layers, or portions should not be limited by these terms. Instead, these terms are used solely to distinguish one member, component, region, layer, or portion from another member, component, region, layer, or portion. Thus, what is referred to as a first member, first component, first region, first layer, or first portion in the examples described herein may also be referred to as a second member, second component, second region, second layer, or second portion without departing from the teachings of the examples.

[0037] In the specification, when an element (such as a layer, region, or substrate) is described as being “on,” “connected to,” or “coupled to” another element, the element may be directly “on,” “connected to,” or “coupled to” the other element, or one or more other elements may be present therebetween. Conversely, when an element is described as being “directly on,” “directly connected to,” or “directly coupled to” another element, there may be no other elements present therebetween.

[0038] The terms used herein are only used to describe various examples and are not intended to limit the disclosure. Unless the context clearly indicates otherwise, the singular is intended to include the plural. The terms "comprise," "include," and "have" indicate the presence of the recited features, quantities, operations, components, elements, and / or combinations thereof, but do not preclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0039] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure pertains after understanding the present disclosure. Unless expressly defined otherwise herein, terms (such as those defined in general dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and the present disclosure, and should not be interpreted in an idealized or overly formal manner.

[0040] Furthermore, in describing the examples, when it is deemed that a detailed description of well-known related structures or functions would cause ambiguous interpretation of the present disclosure, such detailed description will be omitted.

[0041] Figure 1 is a graph showing a first example of fluctuations in a given pitch speed, Figure 2 is a graph showing a second example of fluctuations in a given pitch speed, Figure 3 is a graph showing a third example of fluctuations in a given pitch speed, Figure 4 is a graph illustrating a fourth example in which a given pitch speed fluctuates.

[0042] Reference Figures 1 to 4 The horizontal axis represents time, and the vertical axis represents the given pitch speed. In the first, second, and fourth examples, fluctuations in the given pitch speed caused blade sticking. In the third example, fluctuations in the given pitch speed caused the pitch motor to overheat, triggering the motor overtemperature protection.

[0043] In the first example, the fluctuation amplitude of the given pitch speed is 8 degrees / second, in the second example, the fluctuation amplitude of the given pitch speed is 2 degrees / second, in the third example, the fluctuation amplitude of the given pitch speed is 3 degrees / second, and in the fourth example, the fluctuation amplitude of the given pitch speed is only 0.5 degrees / second. In the first and second examples, the fluctuation frequency of the given pitch speed is high (the curve is relatively dense), and in the third and fourth examples, the fluctuation frequency of the given pitch speed is low (the curve is relatively sparse). In addition, in the fourth example, while the given pitch speed fluctuates, the overall trend is also changing. Therefore, whether it is a method of using a fixed frequency and amplitude for fluctuation detection or a method of executing a fixed speed output after detecting the fluctuation, it is difficult to cover all situations from the first to the fourth examples. In fact, the operating conditions of a wind turbine generator set are far more than these four, so the existing methods cannot effectively handle fluctuations and ensure the safe operation of the wind turbine.

[0044] Figure 5 FIG. 1 is a schematic diagram illustrating a conventional method of detecting a ripple frequency. Figure 5 The upper part shows the fluctuation data, Figure 5The lower half of shows the discretized curve according to the positive and negative signs of the fluctuation data.

[0045] Figure 5 The method described can be used to detect data fluctuations. However, when applied to real-time wind turbine control, it has serious drawbacks. First, it can only detect the magnitude of the fluctuation frequency. However, because the amplitude and period of a given pitch speed fluctuation are uncertain, it is difficult to obtain an accurate speed value when processing a given pitch speed fluctuation.

[0046] Specifically, in order to distinguish it from the normal given pitch speed, the fluctuation amplitude must be determined. However, taking the time t1-t2 in the figure as an example, if the data fluctuation frequency is very high, then the value corresponding to t1-t2 is equal to the fluctuation amplitude; however, when the data fluctuation frequency is low (such as Figure 4 The situation shown is characterized by a small slope of the curve). The value corresponding to t1-t2 is not the true fluctuation amplitude of the curve. Using the value corresponding to t1-t2 to judge the fluctuation will result in missed judgment, and the speed value after processing will still have large fluctuations.

[0047] If the fluctuation amplitude is calculated by averaging the data within a certain period, the fluctuation period is not fixed, so the calculated average value will not match the fluctuation period, resulting in deviation and causing the output value to remain unchanged within the filter window. On the other hand, if the average value is calculated based on high and low levels, the fluctuation period is not fixed, so a small value before time t1 may fall within the time period of the requested average value, resulting in an inaccurate calculated average value.

[0048] Figure 6 is a flow chart illustrating a pitch control method of a wind turbine generator system according to an embodiment of the present disclosure.

[0049] Reference Figure 6In step S601, the given pitch speed may be discretized based on the direction of change of the given pitch speed. According to an embodiment of the present disclosure, when the rate of change of the given pitch speed is a positive value, the direction of change of the given pitch speed may be determined as a first direction, and when the rate of change of the given pitch speed is a negative value, the direction of change of the given pitch speed may be determined as a second direction. In this way, whenever the rate of change of the given pitch speed changes between positive and negative values, it may be determined that the direction of change of the given pitch speed has changed. More specifically, the current given pitch speed may be set to a first discrete value based on the direction of change of the given pitch speed being in the first direction, and the current given pitch speed may be set to a second discrete value based on the direction of change of the given pitch speed being in the second direction. Here, the first discrete value may be one of 0 and 1, and the second discrete value may be the other of 0 or 1. For example, when the rate of change of the given pitch speed is a positive value, the first discrete value may be 1, and when the rate of change of the given pitch speed is a negative value, the second discrete value may be 0.

[0050] Figure 7 is a diagram illustrating an example of discretizing a given pitch speed according to an embodiment of the present disclosure.

[0051] Reference Figure 7 , Figure 7 The upper part of shows the fluctuation data (i.e., for a given pitch speed), Figure 5 The lower half of shows the discretized curve according to the change direction of the fluctuation data (ie, the given pitch speed). Figure 7 As shown, when the rate of change of the given pitch speed is greater than 0 (i.e., the direction of change of the given pitch speed is the first direction), the given pitch speed can be set to a high level 1, and when the rate of change of the given pitch speed is less than 0 (i.e., the direction of change of the given pitch speed is the second direction), the given pitch speed can be set to a low level. Optionally, when the rate of change of the given pitch speed is 0, the given pitch speed can be set to the same discrete value as the previous moment. This method of discretizing the given pitch speed can not only be used to detect whether the given pitch speed fluctuates, but also can accurately identify the maximum and minimum values within a predetermined interval (i.e., the interval of high level 1 or low level 0), so that the accurate average value of the given pitch speed can be obtained, thereby correctly performing pitch control of the wind turbine. In addition, this method of discretizing the given pitch speed is automatically associated with the fluctuation period of the given pitch speed, and does not require any parameter threshold setting. From Figure 7As can be seen from the figure, as the pitch speed fluctuation period changes, the duration of the discretized high and low levels (horizontally) also changes, causing the calculated mean to automatically change. Furthermore, this discretization method for a given pitch speed also eliminates the need to detect the fluctuation amplitude, as the accurate fluctuation centerline can already be calculated.

[0052] Return to reference Figure 6 , in step S602, the fluctuation frequency of the given pitch speed may be determined in response to a change in the direction of change of the given pitch speed. Specifically, the fluctuation frequency of the given pitch speed may be determined based on the number of first discrete values or the number of second discrete values during a predetermined detection period. Here, the predetermined detection period may include multiple sampling moments. For example, the sampling interval may be 20ms, and the predetermined detection period may be, for example, 200ms, 300ms, 400ms..., but the predetermined detection period is not limited to the above examples. Therefore, the number of 1s or 0s during the predetermined detection period may be converted into the fluctuation frequency of the given pitch speed.

[0053] Next, in step S603, in response to the fluctuation frequency of the given pitch speed being greater than a predetermined threshold, the average of the maximum and minimum values of the given pitch speed during the predetermined time period is calculated. Here, the predetermined time period refers to the time period from the moment when the change direction of the given pitch speed last changed to the moment when the change direction of the given pitch speed this time changed. In other words, if Figure 7 As shown, the predetermined time period may be the time period between each rising edge and falling edge.

[0054] In order to calculate the average value of the maximum and minimum values of a given pitch speed during a predetermined time period, the pitch control method may further include the following steps: continuously reading the given pitch speed; comparing the current given pitch speed with the maximum and minimum values of the given pitch speed that have been read; in response to the current given pitch speed being greater than the maximum value of the given pitch speed, recording the current given pitch speed as the maximum value of the given pitch speed; in response to the current given pitch speed being less than the minimum value of the given pitch speed, recording the current given pitch speed as the minimum value of the given pitch speed. Here, whenever the direction of change of the given pitch speed changes, the maximum value of the given pitch speed may be set to a first initial value, and the minimum value of the given pitch speed may be set to a second initial value, wherein the first initial value is less than the second initial value. In this way, by continuously recording the maximum and minimum values of the given pitch speed, the maximum and minimum values of the given pitch speed during the predetermined time period can be obtained. Thus, when the direction of change of the given pitch speed changes and the fluctuation frequency of the given pitch speed is greater than a predetermined threshold, the maximum and minimum values of the given pitch speed can be immediately obtained to calculate the average value.

[0055] For example, when the direction of change of a given pitch speed changes, the maximum value can be initialized to -10 and the minimum value can be initialized to 10. Thereafter, if the data value at the first sampling moment is 4, then since 4>-10, the maximum value can be recorded as 4, and since 4<10, the minimum value can be recorded as 4. If the data value at the second sampling moment is 3, then since 3<4, the minimum value can be recorded as 3, while the maximum value remains unchanged (i.e., it remains 4). If the data value at the third sampling moment is 5, then since 5>4, the maximum value can be recorded as 5, while the minimum value remains unchanged (i.e., it remains 3). In this way, by continuously recording the maximum and minimum values at each sampling moment, the maximum and minimum values during the predetermined time period can eventually be obtained.

[0056] Return to reference again Figure 6 , in step S604, the calculated average value can be used as the current given pitch control speed to perform the pitch operation. Furthermore, in order to make the calculated average value smoother, a sliding average filter can be performed on the calculated average value, and the filtered average value can be used as the current given pitch control speed to perform the pitch operation. Here, the parameter of the sliding average filter is a positive integer less than or equal to 5. Preferably, the parameter of the sliding average filter can be 2, 3 or 4. The purpose of making the parameter of the sliding average filter as small as possible is to reduce the delay in outputting the given pitch control speed due to the execution of the sliding average filter.

[0057] Optionally, the pitch control method may further include the following steps: in response to the fluctuation frequency of the given pitch speed being less than or equal to a predetermined threshold, performing a pitch operation according to the given pitch speed at the moment when the change direction of the given pitch speed changes.

[0058] According to the embodiment of the present disclosure, the pitch control method of the wind turbine generator set can effectively obtain the fluctuation characteristics and trends of the given pitch speed, and automatically and intelligently obtain the center line of the fluctuating given pitch speed, so as to be applied to the pitch control of the wind turbine generator set. In addition, according to the embodiment of the present disclosure, the pitch control method of the wind turbine generator set can effectively detect when the given pitch speed of the wind turbine generator set fluctuates, and ensure the operating safety of the wind turbine and the accuracy of the pitch control without shutting down the wind turbine generator set. In other words, according to the embodiment of the present disclosure, the pitch control method of the wind turbine generator set can avoid the wind turbine generator set from triggering a fault and avoiding the protective shutdown of the wind turbine generator set, reducing the operating risk and failure rate of the wind turbine generator set, which is of great significance to improving the income of the wind farm, especially avoiding the occurrence of serious accidents.

[0059] Figure 8 is a block diagram illustrating a pitch controller according to an embodiment of the present disclosure.

[0060] Reference Figure 8The pitch controller 800 may include a processor 810 and a memory 820. The processor 810 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 820 may store a computer program to be executed by the processor 810. The memory 820 may include a high-speed random access memory and / or a non-volatile computer-readable storage medium. When the processor 810 executes the computer program stored in the memory 820, the pitch control method of the wind turbine generator set described above may be implemented.

[0061] Optionally, pitch controller 800 can communicate with various other components in the wind turbine generator set via wired / wireless communication, and can also communicate with other devices in the wind farm via wired / wireless communication. In addition, pitch controller 800 can communicate with devices outside the wind farm via wired / wireless communication.

[0062] Figure 9 3 is a schematic diagram illustrating the application effect of the pitch control method of a wind turbine generator set according to an embodiment of the present disclosure.

[0063] Reference Figure 9 , curve 901 represents the original given pitch speed, and curve 902 represents the given pitch speed after being processed by the pitch control method of the wind turbine generator set according to the embodiment of the present disclosure. Figure 9 It can be seen that curve 901 fluctuates frequently, while curve 902 no longer fluctuates frequently, but can follow the changing trend of the original given pitch speed without any serious delay. On the other hand, curve 902 is a continuously changing smooth curve without any long pauses.

[0064] The pitch control method of a wind turbine generator set according to an embodiment of the present disclosure can be written as a computer program and stored on a computer-readable storage medium. When the computer program is executed by a processor, the pitch control method of the wind turbine generator set 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 disk storage, hard disk drive (HDD), solid state drive (SSD), card storage (such as, multimedia card, secure digital (SD) card or ultra fast digital (XD) card), magnetic tape, floppy disk, magneto-optical data storage device, optical data storage device, hard disk, solid state disk and any other device, any other device configured to store the computer program and any associated data, data files and data structures in a non-transitory manner and 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 on a networked computer system so that the computer program and any associated data, data files and data structures are stored, accessed and executed in a distributed manner by one or more processors or computers.

[0065] The pitch control method and pitch controller for a wind turbine generator set according to the embodiments of the present disclosure can address the problems of difficulty in detecting the fluctuation frequency of a given pitch speed and the inability of the current given pitch speed to follow the overall speed change trend. The pitch control method and pitch controller can also address the following issues: In traditional mean filtering methods, a small filter window results in poor filtering effectiveness, while a long filter window can cause the given pitch speed to remain unchanged for extended periods, impacting the safe operation of the wind turbine generator set. The pitch control method and pitch controller can also address the problem of only detecting fluctuations in the given pitch speed and directly triggering a fault shutdown upon detection, resulting in power generation loss. The pitch control method and pitch controller can effectively capture the fluctuation characteristics and trends of the given pitch speed, thereby applying them to the pitch control of a wind turbine generator set. The pitch control method and pitch controller can also effectively address the shortcomings of methods that detect fluctuation slope and number of jumps, such as single jumps, variable periods, and variable amplitudes, and can automatically and intelligently determine the centerline of the fluctuating given pitch speed.

[0066] In addition, the pitch control method and pitch controller of the wind turbine generator set according to the embodiment of the present disclosure can effectively detect when the given pitch speed of the wind turbine generator set fluctuates, and ensure the operational safety of the wind turbine and the accuracy of pitch control without shutting down the wind turbine generator set. In other words, the pitch control method and pitch controller of the wind turbine generator set according to the embodiment of the present disclosure can avoid the wind turbine generator set from triggering faults and avoiding protective shutdowns of the wind turbine generator set, reducing the operational risk and failure rate of the wind turbine generator set, which is of great significance for improving the revenue of the wind farm, especially avoiding the occurrence of serious accidents.

[0067] While some embodiments of the present disclosure have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the disclosure, the scope of which is defined by the claims and their equivalents.

Claims

1. A pitch control method for a wind turbine generator set, characterized in that: The pitch control method comprises: Based on the changing direction of the given pitch speed, the given pitch speed is discretized; In response to a change in the direction of change of the given pitch speed, determining a fluctuation frequency of the given pitch speed; In response to a fluctuation frequency of the given pitch speed being greater than a predetermined threshold, calculating an average of a maximum value and a minimum value of the given pitch speed during a predetermined time period; The calculated average value is used as the current given pitch control speed to perform pitch control operation. The predetermined time period refers to the time period from the moment when the change direction of the given pitch speed is changed last time to the moment when the change direction of the given pitch speed is changed this time.

2. The pitch control method according to claim 1, wherein: In response to the rate of change of the given pitch speed being a positive value, the direction of change of the given pitch speed is determined to be a first direction, and in response to the rate of change of the given pitch speed being a negative value, the direction of change of the given pitch speed is determined to be a second direction. Whenever the rate of change of the given pitch speed changes between positive and negative values, it is determined that the direction of change of the given pitch speed has changed.

3. The pitch control method according to claim 2, wherein: The steps of discretizing the given pitch speed based on the direction of change of the given pitch speed include: Based on the change direction of the given pitch speed being a first direction, setting the current given pitch speed to a first discrete value; Based on the changing direction of the given pitch speed being the second direction, the current given pitch speed is set to a second discrete value.

4. The pitch control method according to claim 3, wherein: In response to a change in the direction of change of the given pitch speed, the step of determining the fluctuation frequency of the given pitch speed comprises: The frequency of fluctuations of a given pitch speed is determined based on the number of first discrete values or the number of second discrete values during a predetermined detection period.

5. The pitch control method according to claim 1, wherein: The pitch control method further includes: Continuously read the given pitch speed; Compare the current given pitch speed with the maximum value and the minimum value of the given pitch speed that has been read; In response to the current given pitch speed being greater than the maximum value of the given pitch speed, recording the current given pitch speed as the maximum value of the given pitch speed; In response to the current given pitch speed being less than the minimum value of the given pitch speed, recording the current given pitch speed as the minimum value of the given pitch speed, Whenever the direction of change of the given pitch speed changes, the maximum value of the given pitch speed is set to a first initial value, and the minimum value of the given pitch speed is set to a second initial value, wherein the first initial value is smaller than the second initial value.

6. The pitch control method according to claim 1, wherein: The steps of performing a pitch control operation by using the calculated average value as the current given pitch control speed include: Perform sliding average filtering on the calculated average value, and use the filtered average value as the current given pitch control speed to perform pitch operation. The parameter of the sliding average filter is a positive integer less than or equal to 5.

7. The pitch control method according to claim 1, wherein: The pitch control method further includes: In response to the fluctuation frequency of the given pitch speed being less than or equal to a predetermined threshold, a pitch operation is performed according to the given pitch speed at a moment when a change direction of the given pitch speed changes.

8. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the pitch control method of a wind turbine generator set according to any one of claims 1 to 7 is implemented.

9. A pitch controller, characterized in that: The pitch controller comprises: processor; and The memory stores a computer program, and when the computer program is executed by the processor, the pitch control method of the wind turbine generator set according to any one of claims 1 to 7 is implemented.

10. A wind turbine generator set, characterized in that: The wind turbine generator set includes the pitch controller according to claim 9.

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