CN115143033A

CN115143033A - Control method and control device of wind generating set

Info

Publication number: CN115143033A
Application number: CN202110348294.7A
Authority: CN
Inventors: 马磊; 刘星; 许东宁
Original assignee: Xinjiang Goldwind Science and Technology Co Ltd
Current assignee: Xinjiang Goldwind Science and Technology Co Ltd
Priority date: 2021-03-31
Filing date: 2021-03-31
Publication date: 2022-10-04

Abstract

A control method and a control device of a wind generating set are disclosed. The control method comprises the following steps: periodically calculating a statistic value of the blade angle value measured by the encoder in a sampling time interval; determining that the encoder measured blade angle value fluctuates in response to the calculated statistical value for a consecutive plurality of sampling time intervals being greater than a predetermined threshold; performing a particular pitch operation in response to determining that the encoder measured blade angle values fluctuate.

Description

Control method and control device of wind generating set

Technical Field

The present disclosure relates generally to the field of wind power generation, and more particularly, to a control method and a control apparatus for a wind turbine generator system.

Background

With the gradual expansion of the scale of the wind generating set and the gradual improvement of the safety protection of the set, the power generation performance of the operation of the wind generating set, namely, the improvement of the generated energy and the availability of the wind generating set, is more and more emphasized. On the other hand, the safety of the wind generating set is strictly ensured while the power generation benefit is pursued.

In a wind power plant, one of the main functions of the pitch system is to act as a pneumatic brake system for the plant. The electric variable pitch system ensures the safe and stable operation of the wind generating set through various detection and control means and multiple redundancy design. Any shutdown caused by a fault will feather the blades to the 90 degree position. Therefore, in order to protect the safety of the wind generating set, the pitch system needs to monitor the sensor data and signals in real time during the operation process. If sensor data and signals are abnormal, emergency feathering is required to retract the blades to a safe position. Here, an important sensor data is the blade angle values measured by the encoders of the pitch system.

Meanwhile, the variable pitch drive needs to acquire signals of the encoder, so that when the encoder is damaged or signals of the encoder are abnormal, an angle value acquired by the variable pitch controller/main controller jumps, the wind driven generator is triggered to fail and stops, even abnormal operation and increased current of the variable pitch motor can be caused, the internal trigger failure of the variable pitch drive is caused and the wind driven generator stops, and a pitch clamping phenomenon occurs.

The encoder is a relatively precise and sensitive device. The abnormal working environment can cause the damage of the encoder. Generally, the following factors are the main causes of encoder failure.

First, the encoder itself fails or the grating is contaminated. This is due to the failure of the components of the encoder itself.

Second, the encoder connection cable fails. This is the most likely case, usually with open, short or poor contact of the encoder cable, or with loose cables that are not tightly secured, causing open or broken solder joints.

Third, the encoder +5V supply drops. This means that the +5V power is too low, and usually the power cannot be lower than 4.75V, which causes the power source to be too low due to the loss caused by the power supply failure or the large resistance of the power transmission cable.

Fourthly, the shielding wire of the encoder cable is not jointed or falls off. This condition introduces interference signals, which destabilizes the waveform and affects the accuracy of the communication.

In these cases, when the connection line of the encoder is loosened or the encoder has a device failure, the data output by the encoder may fluctuate greatly and at high frequency. At the moment, the main controller can detect that the three-axis angles of the wind generating set are inconsistent, so that the angle adjusting function is started. However, the angular data measured by the encoder frequently fluctuate, which may cause the given speed value to be disordered, and in the case of frequent and violent pitch adjustment and commutation, the toothed belt may be broken due to frequent sudden changes of force.

In addition, because the fluctuation frequency of the angle data measured by the encoder is high, and the time that the angle difference value of the three blades is continuously larger than a certain threshold value is short, the self-feathering can be executed without triggering the fault of 'angle inconsistency' in the variable pitch system, and the operation safety of the unit is seriously influenced.

At present, four methods for detecting whether an encoder fails are mainly used, and each method is directed at a single jump of the encoder, however, the method for detecting a single jump cannot be used for detecting a situation that an angle value fluctuates greatly and frequently, for the following reasons.

A method for detecting single jump is to judge the change rate before and after the angle value measured by the encoder and carry out amplitude limiting on the jump value. In the method, because the jumping time and jumping amplitude of different encoders are different, the parameter threshold is difficult to reasonably set; in addition, when the actual rotating speed of the variable pitch motor becomes larger, the angle change value of the encoder becomes larger, and if the change rate is processed according to jump, the detection of the real fault of the variable pitch motor is shielded, which is not beneficial to the safety of the wind generating set; in addition, the method cannot distinguish whether the variable pitch motor operates abnormally or the encoder data is abnormal.

Another method of detecting a single transition is to install a vane encoder as a reference. The disadvantages of this method are: on one hand, the value of which encoder is a true value cannot be judged, and on the other hand, some variable pitch system blades cannot be provided with encoders.

Another way to detect a single transition is to increase the detection delay time. The method can filter data of single jump, but when the encoder data fluctuates, the timer in the controller software is frequently switched on and interrupted, so that the timing time of the timer cannot reach a set value all the time, and the fault cannot be triggered, namely, the detection of the abnormal fluctuation of the encoder data cannot be realized; meanwhile, the safety of the wind driven generator is affected because the fault cannot be triggered.

Another method for detecting single jump needs to make redundancy design according to the current value of the motor, or the given speed value, or the actual speed at the previous moment. The disadvantages of this method are: under the condition that the angle value fluctuates frequently, the given speed changes, so that the current value of the variable pitch motor changes, and the actual speed at the previous moment can also be in a jumping state, so that the actual speed at the previous moment cannot be adopted, and the method fails.

Disclosure of Invention

The embodiment of the disclosure provides a control method and a control device of a wind generating set, which can accurately detect whether a blade angle value measured by an encoder fluctuates and make up for the defects of a single-jump detection method.

In one general aspect, there is provided a control method of a wind turbine generator system, the control method including: periodically calculating a statistic value of the blade angle value measured by the encoder in a sampling time interval; determining that the encoder measured blade angle value fluctuates in response to the calculated statistical value for a consecutive plurality of sampling time intervals being greater than a predetermined threshold; performing a particular pitch operation in response to determining that the encoder measured blade angle values fluctuate.

Optionally, the statistical values comprise variance and standard deviation.

Optionally, the encoder is an encoder of a pitch system of a wind park, and the pitch system of the wind park comprises a plurality of encoders, wherein for each encoder the step of calculating the statistical value and its subsequent steps are performed.

Optionally, performing the specific pitch operation comprises one of: executing a blade retracting operation aiming at each blade so as to stop the wind generating set; and disconnecting the external variable-pitch safety chain and executing open-loop feathering operation.

Optionally, the step of performing a specific pitch operation comprises: performing the specific pitch operation based on the blade angle values measured by the encoder and the blade angle values measured by another encoder in a plurality of consecutive predetermined time intervals, wherein the other encoder is an encoder in which the measured blade angle values do not fluctuate.

Optionally, the step of performing a specific pitch operation comprises: calculating a first angle change amount and a value of each of the consecutive predetermined time intervals; calculating a second angle change amount and a value for each of the consecutive predetermined time intervals; comparing the first angle change amount sum value and the second angle change amount sum value for each predetermined time interval; stopping the blade angle consistency adjustment operation in response to the comparison result indicating that the first angle change amount and the value at each predetermined time interval are consistent with the second angle change amount and the value, wherein each predetermined time interval comprises a plurality of sampling moments, each sampling time interval comprises a plurality of sampling moments, and wherein the first angle change amount and the value at any one predetermined time interval are calculated by: calculating an angle change amount between the blade angle value measured by the encoder at each sampling time and the blade angle value measured at the previous sampling time from the first sampling time, and summing all the calculated angle change amounts as a first angle change amount and value of the arbitrary one predetermined time interval, wherein a second angle change amount and value of the arbitrary one predetermined time interval is calculated by: and calculating the angle change amount between the blade angle value measured by the other encoder at each sampling moment and the blade angle value measured at the last sampling moment from a first sampling moment, and summing all the calculated angle change amounts to be used as a second angle change amount sum value of any one preset time interval, wherein the last sampling moment of the first sampling moment is the last sampling moment of the previous preset time interval, and the last sampling moment of the first preset time interval is the last sampling moment of the continuous multiple sampling time intervals.

Optionally, the step of performing a specific pitch operation further comprises: and in response to the comparison result indicating that the first angle variation and value and the second angle variation and value of each preset time interval are consistent, performing a feathering operation on each blade to stop the wind generating set.

Optionally, the step of performing a feathering operation for each blade to stop the wind turbine generator system comprises: calculating a current blade angle value based on a blade angle value at a sampling time before the sampling time at which the blade angle value measured by the encoder jumps, a first angle variation and value at each predetermined time interval, and the number of sampling times at each predetermined time interval; based on the current blade angle value, and executing a blade retracting operation aiming at the blade corresponding to the encoder.

Optionally, the step of calculating the current blade angle value comprises: adding the first angle change amount and the value of each preset time interval to obtain the angle change amount sum; multiplying the sum of the angle variations by a sum of sampling times from a sampling time at which a blade angle value measured by the encoder jumps to a current sampling time, and dividing a result of the multiplication by the sum of the sampling times at the consecutive predetermined time intervals to obtain an additional angle variation value; and adding the blade angle value of the blade angle measured by the encoder at the previous sampling moment of the sampling moment when the blade angle value jumps to the additional angle change value to obtain the current blade angle value.

Optionally, the step of performing a specific pitch operation further comprises: and in response to the comparison result indicating that the first angle variation and value of each preset time interval are consistent with the second angle variation and value, disconnecting the external variable-pitch safety chain and executing open-loop feathering operation.

Optionally, the time length of the predetermined time interval is the same as the time length of the sampling time interval, or the time length of the predetermined time interval is different from the time length of the sampling time interval.

Optionally, each sampling-time interval comprises at least 5 sampling instants, and the number of the consecutive sampling-time intervals is an integer greater than 3.

Optionally, each predetermined time interval comprises at least 5 sampling instants, and the number of the consecutive predetermined time intervals is an integer greater than 5.

In another general aspect, there is provided a control apparatus of a wind turbine generator system, the control apparatus including: a statistic calculation unit configured to periodically calculate a statistic of the blade angle values measured by the encoder during a sampling time interval; a fluctuation determining unit configured to determine that the blade angle value measured by the encoder fluctuates in response to the calculated statistical value of the consecutive plurality of sampling time intervals being greater than a predetermined threshold value; a pitch control unit configured to perform a specific pitch operation in response to determining that the blade angle value measured by the encoder fluctuates.

In another general aspect, there is provided a computer readable storage medium having stored thereon a computer program which, when being executed by a processor, carries out the method of controlling a wind park as described above.

In another general aspect, there is provided a controller, including: a processor; and a memory storing a computer program which, when executed by the processor, implements the control method of the wind turbine generator set as described above.

According to the control method and the control device of the wind generating set, disclosed by the embodiment of the disclosure, angle variation can be accumulated and summed based on the characteristics of angle value fluctuation and the characteristics of angle value recovery after jumping, so that the jumping value of the angle is effectively removed, and a real data value is restored. In addition, according to the control method and the control device of the wind generating set, the blade angle value measured by the encoder is subjected to fluctuation detection and processing, the toothed belt of the variable pitch motor can be prevented from being broken due to frequent fluctuation of a given value, the safety of mechanical parts is protected, and further loss is avoided. Optionally, after detecting that the angle value of the blade measured by the encoder fluctuates frequently, the control method and the control device of the wind generating set according to the embodiment of the disclosure can collect and calculate the difference value of the angle values of the blade at two adjacent sampling moments, accumulate and sum the difference value, compare the sum value with the data of a normal axis, and if the comparison result is consistent, judge that the encoder fluctuates indeed, rather than the operation problem of the variable pitch system. Compared with the existing methods such as an amplitude method and a current method, the detection method is more effective in detecting the frequent fluctuation, and can not cause false detection and missing detection.

In addition, after the fluctuation of the blade angle value measured by the encoder is detected, the control method and the control device of the wind generating set according to the embodiment of the disclosure can stop the consistency adjustment of the three-blade angle, and prevent serious accidents caused by abnormal given speed. Compared with the existing angle jump detection method, the control method and the control device of the wind generating set according to the embodiment of the disclosure can accurately detect whether the angle value of the blade measured by the encoder fluctuates, and make up for the defects of the single jump detection method, and the reason is that: the single jump needs to be designed redundantly according to the current value of the motor, or the given speed value, or the actual speed at the previous moment, but under the condition that the fluctuation of the angle value is frequent, the given speed changes, so that the current value of the motor changes, and the actual speed at the previous moment is also jumped, so that the angle value of the blade measured at the previous moment cannot be used practically.

In addition, compared with the existing methods such as an amplitude method and a current method, the method has the advantages that the algorithm can be simplified and better effects can be realized by accumulating and summing the angle variation. This is because: if the slope is compared, the selection of the sampling period is not easy to select, and the period selection is not appropriate, so that the calculated slope still changes greatly. Therefore, the control method and the control device of the wind generating set according to the embodiment of the disclosure can accurately identify the fluctuation of the angle value measured by the encoder, protect the safety of the actuating mechanism of the pitch system, and can be applied to the condition of frequent fluctuation of the angle value caused by frequent interruption of PROFIBUS-DP communication.

Additional aspects and/or advantages of the present general inventive concept will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the general inventive concept.

Drawings

The above and other objects and features of the embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings illustrating embodiments, in which:

FIG. 1 is a waveform diagram showing angle data after an encoder failure;

FIG. 2 is a waveform diagram showing given speed data of the master controller after an encoder failure;

FIG. 3 is a diagram illustrating an example of a pitch system of a wind park according to an embodiment of the present disclosure;

FIG. 4 is a flow chart illustrating a control method of a wind park according to an embodiment of the present disclosure;

FIG. 5 is a flow chart illustrating a surge detection process according to an embodiment of the present disclosure;

FIG. 6 is a flow chart illustrating a specific pitch operation according to an embodiment of the present disclosure;

FIG. 7 is a flow chart illustrating a feathering operation according to an embodiment of the present disclosure;

FIG. 8 is a flow chart illustrating a specific pitch operation according to another embodiment of the present disclosure;

fig. 9 is a block diagram illustrating a control apparatus of a wind turbine generator set according to an embodiment of the present disclosure;

FIG. 10 is a block diagram illustrating a controller of a wind park according to an embodiment of the present disclosure;

fig. 11 is a diagram illustrating an application effect of a control method of a wind turbine generator set according to an embodiment of the present disclosure.

Detailed Description

The following detailed description is provided to assist the reader in obtaining a thorough understanding of the methods, devices, and/or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatus, and/or systems described herein will be apparent to those skilled in the art after reviewing the disclosure of the present application. For example, the order of operations described herein is merely an example, and is not limited to those set forth herein, but may be changed as will become apparent after understanding the disclosure of the present application, except to the extent that operations must occur in a particular order. Moreover, descriptions of features known in the art may be omitted for greater clarity and conciseness.

The features described herein may be embodied in different forms and should not be construed as limited to the examples described herein. Rather, the examples described herein have been provided to illustrate only some of the many possible ways to implement the methods, devices, and/or systems described herein, which will be apparent after understanding the disclosure of the present application.

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

Although terms such as "first", "second", and "third" may be used herein to describe various elements, components, regions, layers or sections, these elements, components, regions, layers or sections should not be limited by these terms. Rather, these terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section referred to in the examples described herein could also be referred to as a second element, component, region, layer or section without departing from the teachings of the examples.

In the specification, when an element such as a layer, region or substrate is referred to as being "on," "connected to" or "coupled to" another element, it can be directly on, connected to or coupled to the other element or intervening one or more other elements may be present. In contrast, when an element is referred to as being "directly on," "directly connected to" or "directly coupled to" another element, there may be no intervening elements present.

The terminology used herein is for the purpose of describing various examples only and is not intended to be limiting of the disclosure. The singular is also intended to include the plural unless the context clearly indicates otherwise. The terms "comprises," "comprising," and "having" specify the presence of stated features, quantities, operations, elements, components, 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.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs after understanding the present disclosure. Unless explicitly defined as such herein, terms (such as those defined in general dictionaries) should be interpreted as having a meaning that is 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 sense.

Further, in the description of the examples, when it is considered that detailed description of well-known related structures or functions will cause a vague explanation of the present disclosure, such detailed description will be omitted.

Fig. 1 is a waveform diagram showing angle data after an encoder failure occurs.

In fig. 1, the abscissa is a time value and the ordinate is an angle value (unit is degree). Starting at the moment of-7 seconds, the angle value fluctuates greatly and at high frequency, and because the fluctuation frequency is too high, the time of overlarge triaxial angle difference value every time is always less than the trigger time of the fault timing, and the variable pitch system does not trigger the 'position deviation large fault', so that the variable pitch system does not execute autonomous feathering. And under the condition that the main controller controls the shutdown, the main controller starts the angle consistency adjusting function because the main controller detects that the angles of the three blades are inconsistent. Here, the 0 second time may indicate a time at which a malfunction is triggered due to fluctuation in the angle value (i.e., a time at which the main controller activates the angle consistency adjustment function).

Fig. 2 is a waveform diagram showing given speed data of the main controller after a failure of the encoder.

In fig. 2, the abscissa is a time value and the ordinate is a velocity value (unit is degree/second). Starting at-7 seconds, the given speed value fluctuates frequently, in which case the pitch motor commutates frequently, the toothed belt is stressed frequently, and finally the toothed belt may be broken.

According to the control method and the control device of the wind generating set, the frequent fluctuation of the angle value of the blade measured by the encoder can be effectively detected, and the situation that the toothed belt is stressed and is frequently changed and even is pulled to be broken due to the frequent reversing of the variable pitch motor is avoided. A control method and a control apparatus of a wind turbine generator set according to an embodiment of the present disclosure are described in detail below with reference to fig. 3 to 11.

Fig. 3 is a diagram illustrating an example of a pitch system of a wind park according to an embodiment of the present disclosure.

Referring to fig. 3, the pitch system may comprise a pitch motor 301, a super capacitor 302, a pitch controller 303, a pitch drive 304, an enable switch (limit switch) 305, a brake relay 306 and an encoder 307.

When the pitch drive 304 is operating normally, the enable switch (limit switch) 305 is closed and the pitch drive 304 is powered. When the pitch controller 303 receives a pitch speed indication from a main controller of the wind turbine generator system, or the pitch controller 303 detects that the pitch system is malfunctioning and is autonomously feathering, the pitch controller 303 sends a speed command and an enable signal to the pitch driver 304. After receiving the speed command and the enabling signal, the pitch control driver 304 controls the brake relay 306 to release the brake, and provides output voltage through power output to drive the pitch control motor 301 to rotate, so that the pitch control function is realized.

Encoder 307 may measure a blade angle value of the wind park and provide the measured blade angle value to pitch drive 304 and/or pitch controller 303. Pitch drive 304 and/or pitch controller 303 may calculate the rotational speed of pitch motor 301 based on the read encoder values. Pitch drive 304 compares the calculated rotational speed to the value of the speed command sent to pitch drive 304 by pitch controller 303. If the calculated rotational speed is less than the value of the speed command, pitch drive 304 may increase the voltage of the power output to increase the rotational speed of pitch motor 301. If the calculated rotational speed is greater than the value of the speed command, pitch drive 304 may reduce the voltage of the power output to turn down the rotational speed of pitch motor 301. In this way, the rotational speed of pitch motor 301 can eventually be brought into agreement with the value of the given speed command.

The pitch controller 303 may control the overall operation of the pitch system, and may communicate with a main controller of the wind turbine generator system, receive control instructions sent by the main controller and/or send status information of the pitch system to the main controller. The control method of the wind turbine generator set according to the embodiment of the present disclosure may be performed by a main controller of the wind turbine generator set. However, the present disclosure is not limited thereto. For example, a control method of a wind park according to embodiments of the present disclosure may be performed by each pitch controller.

Fig. 4 is a flowchart illustrating a control method of a wind turbine generator set according to an embodiment of the present disclosure.

Referring to fig. 4, in step S401, a statistical value of the blade angle values measured by the encoder during the sampling time interval may be periodically calculated. The statistical values may include variance and standard deviation. In step S402, it may be determined that the encoder measured blade angle value fluctuates in response to the calculated statistical value for a consecutive plurality of sampling time intervals being greater than a predetermined threshold. Each sampling-time interval may include a plurality of sampling instants (e.g., without limitation, at least 5 sampling instants), and the number of consecutive sampling-time intervals may be, for example, 3 or more. In step S403, in response to determining that the encoder measured blade angle values fluctuate, a specific pitch operation may be performed. Here, the encoder is an encoder of a pitch system of the wind park, and the pitch system of the wind park comprises a plurality (e.g. 3) of encoders. Steps S401 to S403 may be performed for each of a plurality of encoders. Therefore, as described above, the control method of the wind turbine generator set according to the embodiment of the present disclosure may be performed by the main controller of the wind turbine generator set.

However, the control method of the wind park according to embodiments of the present disclosure may be performed by each pitch controller. When the control method of the wind power plant according to embodiments of the present disclosure is performed by each pitch controller, each pitch controller may provide the blade angle values measured by the respective encoder to the main controller of the wind power plant and may receive the blade angle values measured by the other encoders from the main controller of the wind power plant. Furthermore, each pitch controller may perform a specific pitch operation based on the blade angle value measured by the respective encoder and the blade angle values measured by other encoders (i.e. another encoder where the measured blade angle value does not fluctuate) received from the main controller of the wind park in case the blade angle value measured by the respective encoder fluctuates.

According to an embodiment of the present disclosure, steps S401 and S402 may be referred to as a fluctuation detection process. The process of fluctuation detection will be waved in more detail later with reference to fig. 5.

In step S403, in response to determining that the blade angle value measured by the encoder fluctuates, a feathering operation may be performed for each blade to shut down the wind turbine generator system, or an external pitch safety chain may be disconnected and an open-loop feathering operation may be performed. On the other hand, in step S403, a specific pitch operation may be performed based on the encoder-measured blade angle value in which the measured blade angle values fluctuate for a consecutive plurality of predetermined time intervals and the blade angle value measured by another encoder (i.e., an encoder in which the measured blade angle values do not fluctuate). The process of performing a specific pitch operation will be described in more detail later with reference to fig. 6.

Fig. 5 is a flowchart illustrating a fluctuation detection process according to an embodiment of the present disclosure.

Referring to fig. 5, in step S501, a count value n =1 of a counter may be set. In step S502, the blade angle values measured by the encoder over the sampling time interval Ts may be collected. In step S503, a statistic of the blade angle values measured by the encoder within the sampling time interval Ts may be calculated. According to an embodiment of the present disclosure, the sampling time interval Ts may comprise a plurality of sampling instants. For example, the sampling time interval Ts may comprise at least 5 sampling instants. Further, the statistical values may include variance and standard deviation. In step S504, it may be determined whether the calculated statistical value is greater than a predetermined threshold. According to the embodiment of the present disclosure, the predetermined threshold may be arbitrarily set by a person skilled in the art according to actual needs. In general, in the case where the blade angle values measured by the encoder do not fluctuate, the variance of the blade angle values measured by the encoder within the sampling time interval is usually small and does not exceed 2 at most. Therefore, in the case where the statistical value is the variance, the predetermined threshold value may be set to, for example, 5. On the other hand, in the case where the statistical value is the standard deviation, the predetermined threshold value may also be set as appropriate. According to the embodiments of the present disclosure, by using a statistical value (e.g., variance or standard value) of the blade angle values measured by the encoder, it may be more accurately determined whether the blade angle values measured by the encoder fluctuate.

If the calculated statistic is greater than a predetermined threshold, it indicates that the blade angle value measured by the encoder fluctuates during the current sampling interval. At this time, in step S505, the count value of the counter may be increased by 1, that is, count value n = n +1. Then, in step S506, it may be determined whether the count value reaches a threshold number. According to an embodiment of the present disclosure, the threshold number may be, for example, an integer greater than 3, but is not limited thereto. If the count value reaches the threshold number, it indicates that the calculated statistics for the consecutive threshold number of sampling time intervals are all greater than the predetermined threshold. Therefore, in step S507, it may be finally determined that the blade angle value measured by the encoder fluctuates. However, if the count value does not reach the threshold number, then the method may return to step S502 to collect the blade angle value measured by the encoder during the next sampling interval Ts.

However, if the calculated statistical value is not greater than the predetermined threshold, it indicates that the blade angle value measured by the encoder does not fluctuate for the current sampling interval. At this time, it may return to step S501 to reset the count value n =1 of the counter and restart the fluctuation detection process. In other words, as long as the statistical value of the blade angle values measured by the encoder for a certain sampling time interval is not greater than the predetermined threshold value before the count value reaches the threshold number, it is not determined that the blade angle values measured by the encoder fluctuate, and the fluctuation detection process will be restarted. According to the embodiment of the disclosure, the blade angle value measured by the encoder is finally determined to fluctuate by determining that the calculated statistic value of a plurality of continuous sampling time intervals is greater than the predetermined threshold value, so that the accuracy and reliability of determining the fluctuation of the blade angle value measured by the encoder can be further improved.

FIG. 6 is a flow chart illustrating a specific pitch operation according to an embodiment of the present disclosure. As described above, the main controller of the wind turbine generator system may perform a specific pitch control operation on the blade corresponding to the encoder where the measured blade angle value fluctuates, or the pitch controller corresponding to the encoder where the measured blade angle value fluctuates may perform a specific pitch control operation on the blade corresponding thereto.

Referring to fig. 6, in step S601, a first angle change amount and a value for each of a plurality of consecutive predetermined time intervals may be calculated. Here, each predetermined time interval may also include a plurality of sampling instants (e.g., without limitation, at least 5 sampling instants), similar to the sampling time intervals. Further, the time length of the predetermined time interval may be the same as or different from the time length of the sampling time interval. The number of consecutive predetermined time intervals may be, for example, 5 or more.

According to an embodiment of the present disclosure, for each predetermined time interval, an angle change amount between the blade angle value measured by the first encoder at each sampling time and the blade angle value measured at the last sampling time may be calculated from the first sampling time, and all the calculated angle change amounts are summed as the first angle change amount sum value for the predetermined time interval. According to an embodiment of the present disclosure, the first encoder may be an encoder in which the measured blade angle value determined during the fluctuation detection fluctuates. Alternatively, the last sampling instant of the first sampling instant of each predetermined time interval may be the last sampling instant of the previous predetermined time interval. For the first predetermined time interval, the last sampling instant of its first sampling instant may be the last sampling instant in the fluctuation detection process.

In step S602, a second angle change amount and a value for each of a plurality of consecutive predetermined time intervals may be calculated. As described above, each predetermined time interval may include a plurality of sampling instants, and the time length of the predetermined time interval may be the same as or different from the time length of the sampling time interval. According to an embodiment of the present disclosure, for each predetermined time interval, an angle change amount between the blade angle value measured by the second encoder at each sampling timing and the blade angle value measured at the last sampling timing may be calculated from the first sampling timing, and all the calculated angle change amounts are summed as the second angle change amount sum value for the predetermined time interval. According to an embodiment of the present disclosure, the second encoder may be an encoder in which the measured blade angle value determined during the surge detection does not fluctuate.

Next, in step S603, the first angle change amount and value for each predetermined time interval may be compared with the second angle change amount and value. In step S604, in response to the comparison result indicating that the first angle change amount and value and the second angle change amount and value for each predetermined time interval both coincide, the blade angle consistency adjustment operation may be stopped. Here, if the difference between the first angle change amount sum value and the second angle change amount sum value is less than, for example, 0.05 degrees, it can be considered that the first angle change amount sum value coincides with the second angle change amount sum value. The first angle variation and the second angle variation are consistent in a plurality of continuous preset time intervals, and the blade angle value measured by the encoder is determined to be fluctuated actually, and the operation of the variable pitch drive or the variable pitch motor is not abnormal.

More specifically, in step S604, in response to the comparison result indicating that the first angle variation amount and value and the second angle variation amount and value for each predetermined time interval are uniform, a feathering operation may be performed for each blade to stop the wind turbine generator set. An implementation of the feathering operation will be described in more detail below with reference to fig. 7.

Fig. 7 is a flow chart illustrating a feathering operation according to an embodiment of the present disclosure.

Referring to fig. 7, in step S701, a current blade angle value may be calculated based on a blade angle value of a previous sampling time to a sampling time at which a transition of the blade angle value measured by the first encoder occurs, a first angle change amount and value for each predetermined time interval, and the number of sampling times for each predetermined time interval. As described above, the first encoder is an encoder in which the measured blade angle value determined in the fluctuation detection process fluctuates. Specifically, in step S701, first, the first angle change amount and the value for each predetermined time interval may be added to obtain the angle change amount sum. Then, the sum of the angle change amounts may be multiplied by a sum of sampling times elapsed from the sampling time at which the blade angle value measured by the first encoder jumps to the current sampling time, and a result of the multiplication may be divided by a sum of sampling times of a plurality of predetermined time intervals (i.e., a sum of sampling times of all predetermined time intervals from a predetermined time interval to which the sampling time at which the blade angle value measured by the first encoder jumps to the current predetermined time interval) to obtain an additional angle change value. Finally, the blade angle value at the sampling time before the blade angle value measured by the first encoder jumps can be added to the acquired additional angle change value to serve as the current blade angle value.

In step S702, a feathering operation may be performed for a blade corresponding to the encoder based on the current blade angle value. At this time, the retracting operation may be normally performed for the blades corresponding to the other encoders. The process of calculating the current blade angle value is illustrated below with reference to the data given in Table 1.

Table 1 shows data such as the blade angle value, the angle variation amount, and the value of the normal axis (the pitch axis in which the blade angle value measured by the encoder does not fluctuate) and the abnormal axis (the pitch axis in which the blade angle value measured by the encoder fluctuates).

TABLE 1

Referring to table 1, the time length of each predetermined time interval may be, for example, 200ms, and each predetermined time interval may include, for example, 10 sampling instants. As can be seen from table 1, although the angle values of the blades measured by the encoders on the abnormal axes fluctuate, the angle change amounts and values of the normal axes and the abnormal axes per predetermined time intervals are consistent. It follows that the blade angle values measured by the encoders on the abnormal shafts do fluctuate.

Here, it is assumed that the feathering operation is started at the first sampling timing of the sixth predetermined time interval, and the blade angle value at the first sampling timing of the first predetermined time interval has fluctuated. Therefore, by adding the first angle change amounts and the values of the six predetermined time intervals, the sum of the angle change amounts can be obtained to be 5.07. The sum of the sample times experienced from the first sample time of the first predetermined time interval to the first sample time of the sixth predetermined time interval is 50, and the result of the multiplication by 5.07 is 253.5. The result of the multiplication is divided by the sum 60 of the sampling instants of the six predetermined time intervals, and an additional angle change value of 4.23 can be obtained. Finally, the blade angle value 8.91 at the previous sampling time of the first predetermined time interval is added to the obtained additional angle change value 4.23, so that the current blade angle value is 13.14. And the encoder on the normal shaft measures a vane angle value of 13.16, which is substantially the same. Therefore, synchronous blade retracting of the three blades can be realized.

The description given above is merely an example, and the present disclosure is not limited thereto. For example, the feathering operation may be performed starting at any sample time after the fifth predetermined time interval, and the blade angle value thereof may be similarly calculated.

Next, referring back to fig. 6, alternatively, in step S604, in response to the comparison result indicating that the first angle variation sum value and the second angle variation sum value for each predetermined time interval are consistent, the outer pitch safety chain may be disconnected and an open-loop feathering operation may be performed for the blade corresponding to the first encoder.

According to the embodiment of the present disclosure, the advantages of performing the feathering operation or disconnecting the external pitch safety chain by restoring the blade angle value are that: when the angle value measured by the encoder fluctuates too frequently, the change time of the angle value is shorter than the delay time of the fault, so the existing fault in the variable pitch controller/the main controller cannot be triggered; and under the condition of executing the blade retracting operation or disconnecting the external variable-pitch safety chain and executing the open-loop feathering operation by restoring the angle value of the blade, the variable-pitch system can execute constant feathering speed without depending on the angle value measured by the encoder, so that frequent fluctuation of a given speed value can not be caused, and the toothed belt is protected from being pulled apart.

FIG. 8 is a flow chart illustrating a specific pitch operation according to another embodiment of the present disclosure.

Referring to fig. 8, in step S801, a count value m =1 of a counter may be set. In step S802, a first angle change amount and value and a second angle change amount and value for the mth predetermined time interval may be calculated. As described above, for the m-th predetermined time interval, it is possible to calculate, from the first sampling timing, the amount of angle change between the blade angle value measured by the first encoder at each sampling timing and the blade angle value measured at the last sampling timing, and sum all the calculated amount of angle change as the first angle change amount sum value for the predetermined time interval. Meanwhile, for the m-th predetermined time interval, the amount of angle change between the blade angle value measured by the second encoder at each sampling timing and the blade angle value measured at the last sampling timing may be calculated from the first sampling timing, and all the calculated amount of angle change are summed as the second angle change amount sum value for the predetermined time interval. The first encoder may be an encoder in which the measured blade angle value determined in the fluctuation detection process fluctuates, and the second encoder may be an encoder in which the measured blade angle value determined in the fluctuation detection process does not fluctuate. The last sampling instant of the first sampling instant of the mth predetermined time interval may be the last sampling instant of the previous predetermined time interval. When m =1, the last sampling timing of the first sampling timing of the mth predetermined time interval may be the last sampling timing in the fluctuation detection process.

Next, in step S803, the first angle change amount and value of the mth predetermined time interval may be compared with the second angle change amount and value. If the first angle change amount and the value of the mth predetermined time interval coincide with the second angle change amount and the value in step S803, the count value of the counter may be increased by 1, i.e., by making the count value m = m +1, in step S804. Then, in step S805, it may be determined whether the count value reaches a threshold number. According to an embodiment of the present disclosure, the threshold number may be, for example, an integer of 5 or more, but is not limited thereto. If the count value reaches the threshold number in step S805, it indicates that the first angle change amount and value and the second angle change amount and value for m consecutive predetermined time intervals both agree, and therefore, in step S806, the blade angle consistency adjustment operation may be stopped. Further, in step S806, a feathering operation may be performed on the blade corresponding to the first encoder, or the external pitch safety chain may be disconnected and an open-loop feathering operation may be performed. On the other hand, if the count value does not reach the threshold number in step S805, it may return to step S802 to calculate the first angle change amount and value and the second angle change amount and value again for the m-th predetermined time interval.

Alternatively, if in step S803 the first angle change amount and value for the mth predetermined time interval do not coincide with the second angle change amount and value, the method may be exited without performing a specific pitch operation on the blade corresponding to the first encoder. In other words, in this case, it is not assumed that the blade angle value measured by the encoder fluctuates, but other processing (for example, a consistency adjustment operation of the blade angle or other failure operation) is performed.

Fig. 9 is a block diagram illustrating a control apparatus of a wind turbine generator set according to an embodiment of the present disclosure.

The control device 900 of the wind park according to an embodiment of the present disclosure may be implemented in a main controller of the wind park. Alternatively, the control 900 of the wind park may be implemented in the individual pitch controllers of the wind park. As described above, when the control apparatus 900 of the wind park is implemented in each pitch controller of the wind park, each pitch controller may provide the blade angle value measured by the corresponding encoder to the main controller of the wind park and may receive the blade angle values measured by the other encoders from the main controller of the wind park.

Referring to fig. 9, the control apparatus 900 of the wind turbine may include a statistic calculation unit 910, a fluctuation determination unit 920, and a pitch control unit 930. The statistical value calculation unit 910 may periodically calculate a statistical value of the blade angle values measured by the encoder during the sampling time interval. The statistical values may include variance and standard deviation. The fluctuation determining unit 920 may determine that the blade angle value measured by the encoder fluctuates in response to the calculated statistical value of the consecutive sampling time intervals being greater than a predetermined threshold value. The pitch control unit may perform a specific pitch operation in response to determining that the blade angle value measured by the encoder fluctuates. Here, the encoder is an encoder of a pitch system of the wind park and the pitch system of the wind park comprises a plurality (e.g. 3) of encoders. Each sampling-time interval may include a plurality of sampling instants (e.g., without limitation, at least 5 sampling instants), and the number of consecutive sampling-time intervals may be, for example, 3 or more.

Pitch control unit 930 may perform a particular pitch operation in response to determining that the encoder measured blade angle values fluctuate. For example, in response to determining that the encoder measured blade angle values fluctuate, pitch control unit 930 may perform a feathering operation for each blade to shutdown the wind turbine or disconnect the external pitch safety chain and perform an open loop feathering operation. Further, the pitch control unit 930 may perform a specific pitch operation based on the encoder-measured blade angle value in which the measured blade angle values fluctuate for a consecutive plurality of predetermined time intervals and the blade angle value measured by another encoder (i.e., an encoder in which the measured blade angle values do not fluctuate).

In response to determining that the encoder measured blade angle value fluctuates, according to embodiments of the present disclosure, pitch control unit 930 may calculate a first angle change amount and value for each of a consecutive plurality of predetermined time intervals, calculating a second angle change amount and a value for each of a plurality of consecutive predetermined time intervals, the first angle change amount and value and the second angle change amount and value for each predetermined time interval are compared, and in response to the comparison result indicating that the first angle change amount and value and the second angle change amount and value for each predetermined time interval both agree, the vane angle consistency adjustment operation is stopped. Here, each predetermined time interval may also include a plurality of sampling instants (e.g., without limitation, at least 5 sampling instants), similar to the sampling time intervals. Further, the time length of the predetermined time interval may be the same as or different from the time length of the sampling time interval. The number of consecutive predetermined time intervals may be, for example, 5 or more. For each predetermined time interval, the amount of angle change between the blade angle value measured by the first encoder at each sampling timing and the blade angle value measured at the last sampling timing may be calculated from the first sampling timing, and all the calculated amount of angle changes are summed as the first angle change amount sum value for the predetermined time interval. According to an embodiment of the present disclosure, the first encoder may be an encoder in which the determined measured blade angle value fluctuates. Alternatively, the last sampling instant of the first sampling instant of each predetermined time interval may be the last sampling instant of the previous predetermined time interval. For the first predetermined time interval, the last sampling instant of its first sampling instant may be the last sampling instant in the fluctuation detection process. Further, for each predetermined time interval, the amount of angle change between the blade angle value measured by the second encoder at each sampling timing and the blade angle value measured at the last sampling timing may be calculated from the first sampling timing, and all the calculated amount of angle change are summed as the second angle change amount sum value for the predetermined time interval. According to an embodiment of the present disclosure, the second encoder may be an encoder in which the measured blade angle value determined during the surge detection does not fluctuate.

In response to the comparison result indicating that the first angle change amount and the value for each predetermined time interval both coincide with the second angle change amount and value, pitch control unit 930 may perform a feathering operation for the blade corresponding to the first encoder. For example, the pitch control unit 930 may calculate the current blade angle value based on the blade angle value of the previous sampling time to the sampling time at which the blade angle value measured by the first encoder makes a transition, the first angle change amount and value for each predetermined time interval, and the number of sampling times for each predetermined time interval. Specifically, pitch control unit 930 may add the first angle change amount and the value for each predetermined time interval to obtain an angle change amount sum. Then, the pitch control unit 930 may multiply the sum of the angle change amounts by a sum of sampling times elapsed from a sampling time at which the blade angle value measured by the first encoder jumps to a current sampling time, and divide the result of the multiplication by the sum of sampling times of consecutive predetermined time intervals to obtain an additional angle change value. Finally, the pitch control unit 930 may add the blade angle value at the previous sampling time to the sampling time at which the blade angle value measured by the first encoder jumps and the additional angle change value as the current blade angle value. After calculating the current blade angle value, the pitch control unit 930 may perform a feathering operation for the blade corresponding to the first encoder based on the calculated current blade angle value.

Alternatively, in response to the comparison result indicating that the first angle variation amount and value and the second angle variation amount and value for each predetermined time interval both agree, the pitch control unit 930 may disconnect the external pitch safety chain and perform an open-loop feathering operation.

Fig. 10 is a block diagram illustrating a controller of a wind park according to an embodiment of the present disclosure.

Referring to fig. 10, a controller 1000 of a wind park according to an embodiment of the present disclosure may be, but is not limited to, a pitch controller, a main controller of the wind park, etc. As described above, three blades of the wind turbine generator set correspond to one shaft, and each shaft has a pitch controller, a pitch driver, and a pitch motor. The controller 1000 of a wind park according to embodiments of the present disclosure may comprise a processor 1010 and a memory 1020. Processor 1010 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), and the like. The memory 1020 stores computer programs to be executed by the processor 1010. Memory 1020 includes high-speed random access memory and/or non-volatile computer-readable storage media. The control method of the wind park as described above may be implemented when the processor 1010 executes a computer program stored in the memory 1020.

Alternatively, the controller 1000 may communicate with other components in the wind park in wired/wireless communication, and may also communicate with other devices in the wind park in wired/wireless communication. Further, the controller 1000 may communicate with a device outside the wind farm in a wired/wireless communication manner.

Referring to FIG. 11, through the fluctuation detection process and the specific pitch operation, the frequently fluctuating blade angle values (as shown by the thin solid lines in FIG. 11) may be restored to normal blade angle values (as shown by the thick solid lines in FIG. 11).

A control method of a wind park according to an embodiment of the present disclosure may be written as a computer program and stored on a computer readable storage medium. The computer program, when executed by a processor, may implement the control method of a wind park as described above. 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-RW, DVD + RW, DVD-RAM, BD-ROM, BD-R LTH, BD-RE, blu-ray or optical disk memory, hard Disk Drive (HDD), solid State Disk (SSD), card memory (such as a multimedia card, a Secure Digital (SD) card or an extreme digital (XD) card), magnetic tape, a floppy disk, a magneto-optical data storage device, an optical data storage device, a hard disk, a solid state disk, and any other device configured to store and provide computer programs and any associated data, data files and data structures in a non-transitory manner to a computer processor or computer such that the computer programs and any associated data processors are executed or computer programs. In one example, the computer program and any associated data, data files, and data structures are distributed over a network of networked computer systems such that the computer program and any associated data, data files, and data structures are stored, accessed, and executed in a distributed fashion by one or more processors or computers.

According to the control method and the control device of the wind generating set, disclosed by the embodiment of the disclosure, angle variation can be accumulated and summed based on the characteristics of angle value fluctuation and the characteristics of angle value recovery after jumping, so that the jumping value of the angle is effectively removed, and a real data value is restored. In addition, according to the control method and the control device of the wind generating set, the blade angle value measured by the encoder is subjected to fluctuation detection and processing, the toothed belt of the variable pitch motor can be prevented from being broken due to frequent fluctuation of a given value, the safety of mechanical parts is protected, and further loss is avoided. Optionally, after detecting that the blade angle value measured by the encoder fluctuates frequently, the control method and the control device of the wind generating set according to the embodiments of the present disclosure may collect and calculate the difference value between the blade angle values at two adjacent sampling moments, add up and sum the difference value, compare the sum value with the data of the normal axis, and if the comparison result is consistent, determine that the encoder actually fluctuates instead of the operation problem of the pitch system itself. Compared with the existing methods such as an amplitude method and a current method, the detection method is more effective in detecting the frequent fluctuation, and can not cause false detection and missed detection.

In addition, after the fluctuation of the blade angle value measured by the encoder is detected, the control method and the control device of the wind generating set according to the embodiment of the disclosure can stop the consistency adjustment of the three-blade angle, and prevent serious accidents caused by abnormal given speed. Compared with the existing angle jump detection method, the control method and the control device of the wind generating set according to the embodiment of the disclosure can accurately detect whether the angle value of the blade measured by the encoder fluctuates, and make up for the defects of the single jump detection method, and the reason is that: the single jump needs to be designed redundantly according to the motor current value, the given speed value or the actual speed at the previous moment, but under the condition that the angle value fluctuates frequently, the given speed changes, so that the motor current value changes, and the blade angle value measured at the previous moment cannot be used practically because the actual speed at the previous moment is also possible to jump.

In addition, compared with the existing methods such as an amplitude method and a current method, the method has the advantages that the algorithm can be simplified and better effect can be realized by accumulating and summing angle variation. This is because: if the slope is compared, the selection of the sampling period is not easy to select, and the period selection is not appropriate, so that the calculated slope still changes greatly. Therefore, the control method and the control device of the wind generating set according to the embodiment of the disclosure can accurately identify the fluctuation of the angle value measured by the encoder, protect the safety of the actuating mechanism of the pitch system, and can be applied to the condition of frequent fluctuation of the angle value caused by frequent interruption of PROFIBUS-DP communication.

Although a few embodiments of the present disclosure have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the disclosure, the scope of which is defined in the claims and their equivalents.

Claims

1. A control method of a wind generating set is characterized by comprising the following steps:

periodically calculating a statistic value of the angle value of the blade measured by the encoder in a sampling time interval;

determining that the encoder measured blade angle value fluctuates in response to the calculated statistical value for a consecutive plurality of sampling time intervals being greater than a predetermined threshold;

performing a particular pitch operation in response to determining that the encoder measured blade angle values fluctuate.

2. The control method according to claim 1, wherein performing a specific pitch operation comprises one of:

executing a blade retracting operation aiming at each blade so as to stop the wind generating set;

and disconnecting the external variable-pitch safety chain and executing open-loop feathering operation.

3. The control method according to claim 1, characterized in that the step of performing a specific pitch operation comprises:

performing the specific pitch operation based on the blade angle values measured by the encoder and the blade angle values measured by another encoder in a plurality of consecutive predetermined time intervals, wherein the other encoder is an encoder in which the measured blade angle values do not fluctuate.

4. A control method according to claim 3, characterised in that the step of performing a specific pitch operation comprises:

calculating a first angle change amount and a value of each of the consecutive predetermined time intervals;

calculating a second angle change amount and a value for each of the consecutive predetermined time intervals;

comparing the first angle change amount sum value and the second angle change amount sum value for each predetermined time interval;

in response to the comparison result indicating that the first angle change amount and value and the second angle change amount and value for each predetermined time interval both agree, the vane angle consistency adjustment operation is stopped,

wherein each predetermined time interval comprises a plurality of sampling instants, each sampling time interval comprises a plurality of sampling instants,

wherein the first angle change amount and the value of any one predetermined time interval are calculated by: calculating an angle change amount between the blade angle value measured by the encoder at each sampling timing and the blade angle value measured at the last sampling timing from a first sampling timing, and summing all the calculated angle change amounts as a first angle change amount and a value for the arbitrary one predetermined time interval,

wherein the second angle change amount and the value of any one predetermined time interval are calculated by: calculating an angle change amount between the blade angle value measured by the other encoder at each sampling timing and the blade angle value measured at the previous sampling timing from the first sampling timing, and summing all the calculated angle change amounts as a second angle change amount sum value for the arbitrary one predetermined time interval,

wherein the last sampling time of the first sampling time is the last sampling time of the previous predetermined time interval, and the last sampling time of the first predetermined time interval is the last sampling time of the consecutive plurality of sampling time intervals.

5. The control method according to claim 4, wherein the step of performing a specific pitch operation further comprises:

and in response to the comparison result indicating that the first angle variation and value and the second angle variation and value of each preset time interval are consistent, executing a feathering operation for each blade to stop the wind generating set.

6. The control method according to claim 5, wherein the step of performing a feathering operation for each blade to stop the wind turbine generator set comprises:

calculating a current blade angle value based on a blade angle value at a sampling moment before the sampling moment when the blade angle value measured by the encoder jumps, a first angle variation and value at each preset time interval, and the number of the sampling moments at each preset time interval;

and executing a blade retracting operation aiming at the blade corresponding to the encoder based on the current blade angle value.

7. The control method of claim 6, wherein the step of calculating the current blade angle value comprises:

adding the first angle change amount and the value of each preset time interval to obtain the angle change amount sum;

multiplying the sum of the angle variations by a sum of sampling times from a sampling time at which a blade angle value measured by the encoder jumps to a current sampling time, and dividing a result of the multiplication by the sum of the sampling times at the consecutive predetermined time intervals to obtain an additional angle variation value;

and adding the blade angle value of the blade angle value measured by the encoder at the previous sampling moment of the sampling moment when the blade angle value jumps to the additional angle change value to obtain the current blade angle value.

8. The control method according to claim 4, wherein the step of performing a specific pitch operation further comprises:

and in response to the comparison result indicating that the first angle variation and value and the second angle variation and value at each preset time interval are consistent, disconnecting the external variable-pitch safety chain and executing open-loop feathering operation.

9. The control method according to claim 4, wherein a time length of the predetermined time interval is the same as a time length of the sampling time interval or the predetermined time interval is different from the time length of the sampling time interval.

10. A control device of a wind turbine generator set, characterized in that the control device comprises:

a statistic calculation unit configured to periodically calculate a statistic of the blade angle values measured by the encoder during a sampling time interval;

a fluctuation determining unit configured to determine that the encoder measured blade angle value fluctuates in response to the calculated statistical value of the consecutive plurality of sampling time intervals being greater than a predetermined threshold value;

a pitch control unit configured to perform a specific pitch operation in response to determining that the blade angle value measured by the encoder fluctuates.

11. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out a method of controlling a wind park according to any one of claims 1 to 9.

12. A controller, characterized in that the controller comprises:

a processor; and

a memory storing a computer program which, when executed by the processor, implements the method of controlling a wind park according to any one of claims 1 to 9.