CN115875200A - Fault detection method and controller for variable pitch system encoder - Google Patents

Abstract

The fault detection method for the encoder of the variable pitch system comprises the following steps: reading the angle value of the blade at each sampling moment in a preset time period of variable pitch operation; generating a discrete binarization sequence based on the leaf angle value at each sampling moment; and in response to the preset time period expiring, determining whether a variable pitch system encoder fails or not based on the fluctuation frequency of the discrete binarization sequence.

Description

Fault detection method and controller for variable pitch system encoder

Technical Field

The present disclosure relates generally to the field of wind power generation, and more particularly, to a fault detection method and controller for a pitch system encoder of a wind turbine generator system.

Background

The wind driven generator is a device for converting wind energy into electric energy, the wind energy drives the main shaft, the speed increasing box and the generator through the impeller to be converted into electric energy, and the converted electric energy is transmitted to a power grid through grid-connected control. The variable pitch system of the wind generating set plays a vital role in tracking the maximum power of the wind generating set and ensuring the safe shutdown of the wind generating set. The variable pitch system controls the rotating speed of the impeller (namely, the rotating speed of the wind driven generator) by controlling the angle of the blade, so that the output power of the wind driven generator set is controlled, and the wind driven generator set can be safely stopped in an aerodynamic braking mode. Blades of the wind generating set are connected with the hub through a variable pitch bearing, and each blade is provided with a relative independent electrically-controlled synchronous variable pitch system. The pitch system is meshed and linked with the inner teeth of the pitch bearing through a pinion. During normal operation of the wind park, when the wind speed exceeds the rated wind speed of the park (for example, between 12m/s and 25 m/s), the pitch angle is limited to between 0 and 30 degrees for controlling the power output (the pitch angle is automatically adjusted according to the change of the wind speed), and the rotating speed of the wind driven generator is kept constant by controlling the angle of the blades. The shutdown of the wind turbine generator system caused by any situation will cause the blades to feather to the 90 degree position (the blades will feather to the 91 degree limit position when the emergency feathering command is executed).

At present, a control method of a pitch system of a wind generating set comprises the following steps: the method comprises the steps that a main controller of a wind generating set detects an actual rotating speed value of the wind generating set, a target rotating speed value is set according to model characteristics of the wind generating set, PID operation is carried out on deviation between the target rotating speed value and the actual rotating speed value, a blade angle value is output, after a variable pitch system receives the target angle value issued by a main controller, the change of the blade angle value is collected by using an absolute value signal of an encoder, closed-loop PID negative feedback control is formed between the change of the blade angle value and a variable pitch motor, the rotating speed and the direction of the variable pitch motor are controlled, and the variable pitch motor is meshed with an inner gear ring of a propeller hub through a driving gear and directly controls the blade angle.

In addition, the driver of the pitch system (pitch driver) needs to acquire the incremental signal of the encoder to detect the rotation speed and direction of the pitch motor. For example, the positive rotation and the reverse rotation of the encoder can be distinguished by comparing the phase a and the phase B of the incremental signal, and the zero reference bit of the encoder can be obtained by the zero pulse. The incremental signal of the encoder is a function that can convert the rotational motion into an output signal. In combination with a mechanical transmission element (e.g. a rack and pinion, a measuring wheel or a spindle), the incremental signal can likewise measure linear movement. The encoder may convert the position change in increments into a continuous square wave signal output.

The encoder is a relatively precise and sensitive device. The abnormal working environment may cause the damage of the encoder. Generally, the main causes of encoder failure are: 1) The encoder has a fault or grating pollution, which means that the components of the encoder have faults; 2) The shielding wire of the encoder cable is not connected or falls off; 3) The encoder is installed and loosened: 4) Abnormal fluctuations in voltage cause the encoder to burn out.

Because the driver needs to acquire the incremental signal of the encoder, after the encoder is damaged, the position signal detected by the driver can be wrong, so that the operation of the variable pitch motor is abnormal, the current of the motor is increased, and even the driver is stopped due to internal triggering failure. After a driver of the variable pitch system breaks down, the variable pitch system can be blocked, and at the moment, the variable pitch motor can not drive the blades to feather to a safe position, so that great hidden danger is generated on the safety of the wind generating set. In addition, if the single-shaft propeller clamping device is adopted, in the running process of an impeller of the wind generating set, because the positions of the three blades are different, the acting force of wind energy received by the impeller can generate great deviation, namely the stress of the impeller is unbalanced, so that the load of the wind generating set can be greatly influenced, and the service life of the wind generating set is shortened.

However, during troubleshooting, because the encoder (especially the incremental signal of the encoder) does not have a detection signal and a detection device, the existing method for troubleshooting or detecting the encoder fault generally performs a test after the encoder is replaced, and the encoder is installed inside the variable pitch motor, which takes time for both disassembly and assembly, thereby bringing great inconvenience to operation and maintenance. In addition, because the encoder signal belongs to a high-frequency signal, no better device or circuit for detecting the encoder signal exists at present, so that the troubleshooting of the encoder fault is difficult and the time consumption is long.

Disclosure of Invention

The embodiment of the disclosure provides a fault detection method and a controller for a variable pitch system encoder, which can reduce the troubleshooting time of the encoder fault, improve the operation and maintenance efficiency, and reduce the downtime of a wind generating set caused by the encoder fault.

In one general aspect, there is provided a fault detection method of a pitch system encoder, the fault detection method comprising: reading a blade angle value at each sampling moment in a preset time period of variable pitch operation; generating a discrete binarization sequence based on the blade angle value at each sampling moment; and in response to the preset time period expiring, determining whether a variable pitch system encoder fails or not based on the fluctuation frequency of the discrete binarization sequence.

Optionally, the fault detection method further includes: updating the count values of a preset angle unchanged counter, an angle ascending counter and an angle descending counter based on the blade angle value at each sampling moment, wherein the step of determining whether the variable pitch system encoder fails or not based on the fluctuation frequency of the discrete binarization sequence comprises the following steps of: and determining that the variable pitch system encoder fails in response to the fact that the fluctuation frequency of the discrete binarization sequence is greater than a preset threshold value and the count values of the angle unchanged counter, the angle ascending counter and the angle descending counter meet preset conditions.

Optionally, the preset condition includes: the count value of the angle rising counter is greater than or equal to the difference between the number of sampling moments in the preset time period and the count value of the angle unchanged counter, and the count value of the angle falling counter is zero; or the count value of the angle down counter is greater than or equal to the difference between the number of sampling moments in the preset time period and the count value of the angle unchanged counter, and the count value of the angle up counter is zero.

Optionally, the step of generating binarized discrete data based on the leaf angle value at each time includes: in response to the fact that the angle value of the blade at the current moment is different from the angle value at the previous moment, setting the position, corresponding to the current moment, in the discrete binarization sequence to be 1; and in response to the blade angle value at the current moment being the same as the angle value at the previous moment, setting the position corresponding to the current moment in the discrete binarization sequence to be 0.

Optionally, the fault detection method further includes: reading a given variable pitch speed value at each moment in a preset time period, wherein the step of generating binary discrete data based on the blade angle value at each moment comprises the following steps: in response to the difference between the angle value of the blade at the current moment and the angle value at the previous moment, setting the position corresponding to the current moment in the discrete binarization sequence to be 1; in response to that the blade angle value at the current moment is the same as the angle value at the previous moment and the given variable pitch speed value at the current moment is not zero, setting the position corresponding to the current moment in the discrete binarization sequence to be 0; and in response to that the blade angle value at the current moment is the same as the angle value at the previous moment and the given variable pitch speed value at the current moment is zero, setting the position corresponding to the current moment in the discrete binarization sequence as the value of the position corresponding to the previous moment.

Optionally, the fluctuation frequency of the discrete binarization sequence is calculated based on the number of changes from 0 to 1 or the number of changes from 1 to 0 in the discrete binarization sequence and the duration of the preset time period.

Optionally, the step of updating the count values of the preset angle unchanged counter, the angle up counter and the angle down counter based on the blade angle value at each sampling time includes: in response to the blade angle value at the current moment being different from the angle value at the previous moment, incrementing the count value of the angle-unchanged counter by 1, and in response to the blade angle value at the current moment being the same as the angle value at the previous moment, keeping the count value of the angle-unchanged counter unchanged; increasing the count value of the angle increase counter by 1 in response to the blade angle value at the present time being greater than the angle value at the previous time, and maintaining the count value of the angle increase counter unchanged in response to the blade angle value at the present time being less than or equal to the angle value at the previous time; the count value of the angle down counter is incremented by 1 in response to the blade angle value at the present time being less than the angle value at the previous time, and the count value of the angle down counter is maintained in response to the blade angle value at the present time being greater than or equal to the angle value at the previous time.

Optionally, the count values of the angle no-change counter, the angle up counter and the angle down counter are cleared in response to the start of the preset time period.

Optionally, the step of determining that the pitch system encoder is malfunctioning comprises: and determining that the incremental signal abnormal fault occurs in the variable pitch system encoder, and outputting alarm information indicating the incremental signal abnormal fault.

According to another aspect of the present disclosure, there is provided a computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements a method of fault detection of a pitch system encoder as described above.

According to another aspect of the present disclosure, there is provided a controller including: a processor; and a memory storing a computer program which, when executed by the processor, implements the method of fault detection of a pitch system encoder as described above.

According to another aspect of the present disclosure, there is provided a wind park comprising a controller as described above.

According to the fault detection method and the controller of the encoder of the variable pitch system, whether the encoder has a fault can be directly judged only through the operation condition of the angle value of the blade, the method and the controller are suitable for variable pitch systems of various types, and the method and the controller have important significance for improving the fault elimination efficiency of the encoder and reducing the power generation loss.

In addition, according to the fault detection method and the controller of the variable pitch system encoder, early warning of encoder faults can be achieved, therefore, open-loop feathering of the variable pitch system can be triggered in advance, and the condition that the angles of the three blades are unbalanced due to short-time blade clamping is prevented.

In addition, according to the fault detection method and the controller of the variable pitch system encoder, the encoder fault can be effectively distinguished from the conditions of mechanical clamping stagnation, given speed fluctuation and the like, so that the fault detection precision is improved.

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 diagram showing a pitch cabinet topology of a wind turbine generator set and encoder signal transmission;

fig. 2 is a diagram showing an example of an incremental signal of an encoder;

fig. 3 is a graph showing a change curve of the angle values of three blades in the case where the incremental signal of the encoder is abnormal;

fig. 4 is a diagram showing a curve 301 in fig. 3 enlarged;

FIG. 5 is a flow chart illustrating a fault detection method of a pitch system encoder according to an embodiment of the present disclosure;

FIG. 6 is a block diagram illustrating a controller according to an embodiment of the present disclosure;

FIG. 7 is a diagram showing an application example of a fault detection method of a pitch system encoder according to an embodiment of the present disclosure;

FIG. 8 is a graph illustrating blade angle values that trigger pitch system open loop feathering when a pitch system encoder fails.

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 clarity and conciseness.

Fig. 1 is a diagram showing a pitch cabinet topology of a wind turbine generator set and encoder signal transmission.

Referring to fig. 1, the pitch controller 11 and the pitch drive 12 are disposed inside the pitch cabinet 10, while the encoder 13 is disposed outside the pitch cabinet 10 and mounted inside a pitch motor (not shown).

The signal lines of the encoder 13 are respectively connected to the devices inside the pitch control cabinet 10 through the wiring plugs on the cabinet body of the pitch control cabinet 10. For example, the absolute value signal of the encoder 13 is transmitted to an encoder signal acquisition module of the pitch controller 11 for calculating the blade angle value, and the incremental signal of the encoder 13 is transmitted to the pitch driver 12 for calculating the rotation speed of the pitch motor.

As described above, since there is no device dedicated to detecting the encoder incremental signal in the prior art, the existing method for checking or detecting the encoder fault generally replaces and observes the encoder, which brings great inconvenience to operation and maintenance. Furthermore, when an early slight abnormality occurs in the encoder increment signal, it is difficult to detect and find the abnormality in the conventional fault detection method.

Fig. 2 is a diagram showing an example of an incremental signal of an encoder.

Referring to fig. 2, the encoder directly outputs three sets of square wave pulses, i.e., a-phase, B-phase, and Z-phase pulses, using the photoelectric conversion principle. The phase difference between the A-phase pulse and the B-phase pulse is 90 degrees, and the rotation direction (forward direction or reverse direction) of the encoder (variable pitch motor) can be judged by judging whether the phase of the A-phase pulse is in front or the phase of the B-phase pulse is in front. In addition, the encoder generates one Z-phase pulse per revolution (360) for reference point positioning. CLK is the encoder's clock signal used to assist in the generation of the a-, B-, and Z-phase pulses.

The rotating speed value of the pitch motor is usually calculated according to the number of A-phase pulses and B-phase pulses in a certain time. Assuming that the number of pulses acquired by the pitch drive in t time is m and the number of pulses generated by the encoder per 360 ° rotation is N, the number of revolutions corresponding to the number of pulses m in t time is: a = m/N. Accordingly, the rotational speed value N =60 × 1000 × m/N × t of the pitch motor may be calculated. Because the frequency of the clock signal of the encoder can reach 4096 or 8192 pulses per revolution, the rotating speed value of the variable pitch motor can also reach high measurement accuracy.

From N =60 × 1000 × m/N × t, the value of the rotation speed of the pitch motor depends mainly on the number m of pulses in t time. When an abnormality (e.g., signal interference, disconnection) or the like occurs in the incremental signal of the encoder, the number of pulses m decreases, and the calculated rotation speed value decreases. Since pitch control requires that the measured rotational speed value track a given target speed, the voltage of the pitch motor will increase, for reasons described below.

The rotating speed calculation formula of the variable pitch motor is as follows: n =60f/p (1-s), where f is the supply frequency of the pitch motor and s is the rotational speed difference. From the above formula it can be seen that if it is desired to increase the rotational speed of the pitch motor, the frequency f needs to be increased. Furthermore, in the process of frequency conversion and speed regulation, the magnetic flux of the motor needs to be enabled

Essentially constant, u/f must be made ≈ const, i.e. the stator voltage u needs to be changed while the frequency f is changed. Hold and/or>

The unchanged approach is to keep the voltage regulation ratio ku equal to the frequency regulation ratio kf, i.e. ku = kf. Therefore, the voltage of the pitch motor is increased while the frequency is adjusted. On the other hand, since u/f ≈ const (constant), in the case where the frequency is low and the torque is insufficient, in order to make the pitch motor reach a sufficient output torque and track a given target speed, the current of the pitch motor needs to be increased.

Fig. 3 is a graph showing a change curve of the angle values of three blades in the case where the incremental signal of the encoder is abnormal.

Referring to fig. 3, the abscissa represents time, and the ordinate represents a blade angle value, where time 0 is a time at which a fault is triggered, that is, time 0 and left and right are blade angle values before and after the fault, respectively. Curve 301 is the vane angle value for the shaft with the encoder failing. As can be seen from fig. 3, when the wind turbine generator system triggers a fault shutdown, the remaining two blades are normally feathered, and the feathering speed shown by the curve 301 is slower because: when the encoder has an increment signal abnormal fault, the number of pulses in the same time is reduced, the variable pitch control angle and the operation frequency of the variable pitch motor are reduced, and finally the variable pitch speed of the shaft with the fault of the encoder is slowed down.

Fig. 4 is a diagram showing a curve 301 in fig. 3 enlarged.

Referring to fig. 4, the number of pulses in the same time is reduced, the pitch control angle adjustment and the number of times of driving the pitch motor to operate are reduced, and therefore, the angle value curve has a continuous and high-frequency intermittent interruption phenomenon, namely, a horizontal line segment (as indicated by a square frame in the figure) with no angle change as shown in fig. 4. According to the fault detection method of the variable pitch system encoder, detection and early warning of the increment signal abnormality of the encoder are realized just according to the working mechanism of the encoder when the increment signal is abnormal.

FIG. 5 is a flow chart illustrating a method of fault detection of a pitch system encoder according to an embodiment of the present disclosure. The fault detection method of the pitch system encoder according to the embodiment of the disclosure can be implemented in a pitch controller of a wind generating set, and can also be implemented in a main controller or other special controllers of the wind generating set.

Referring to fig. 5, in step S501, a blade angle value may be read at each sampling instant within a preset time period of a pitch operation. As described above, the vane angle value may be obtained by reading the absolute value signal of the encoder. Alternatively, the preset time period may be repeated periodically during a pitch operation, and the duration of the preset time period may be much greater than the scan period of the pitch controller. For example, the scanning period of the pitch controller is 20ms, and the duration of the preset time period may be 20 × 20ms =400ms, but is not limited thereto.

In step S502, a discrete binarization sequence may be generated based on the leaf angle value at each sampling time. Specifically, if the leaf angle value at the present time is different from the angle value at the previous time, the position in the discrete binarization sequence corresponding to the present time may be set to 1; if the leaf angle value at the current time is the same as the angle value at the previous time, the position in the discrete binarization sequence corresponding to the current time may be set to 0.

Further, in order to effectively distinguish the case of the encoder failure from the case of the given speed fluctuation, the method for detecting the failure of the encoder of the pitch system according to the embodiment of the present disclosure may further read the given pitch speed value at each time within a preset time period. In this way, in the step of generating the discrete binarization sequence, if the angle value of the leaf at the current time is different from the angle value at the previous time, the position in the discrete binarization sequence corresponding to the current time may be set to 1; if the angle value of the blade at the current moment is the same as the angle value at the previous moment and the given variable pitch speed value at the current moment is not zero, setting the position corresponding to the current moment in the discrete binarization sequence as 0; if the blade angle value at the current time is the same as the angle value at the previous time and the given pitch speed value at the current time is zero, the position corresponding to the current time in the discrete binarization sequence may be set to the value of the position corresponding to the previous time (i.e., the value of the position corresponding to the current time is made the same as the value of the position corresponding to the previous time).

Next, in step S503, in response to the expiration of the preset time period, it may be determined whether the pitch system encoder has failed based on the fluctuation frequency of the discrete binarization sequence. Here, the fluctuation frequency of the discrete binarization sequence may be calculated based on the number of changes of 0 to 1 or the number of changes of 1 to 0 in the discrete binarization sequence and the duration of a preset time period. That is, the fluctuation frequency of the discrete binarization sequence may be calculated based on the number of pulses in the discrete binarization sequence and the duration of the preset time period. For example, assuming that the duration of the preset time period is 400ms, if the discrete binarization sequence has only one pulse during the preset time period, the fluctuation frequency of the discrete binarization sequence is 1 × 2.5=2.5hz, and if the discrete binarization sequence has three pulses during the preset time period, the fluctuation frequency of the discrete binarization sequence is 3 × 2.5=7.5hz. For another example, assuming that the duration of the preset time period is 800ms, if the discrete binarization sequence has only one pulse during the preset time period, the fluctuation frequency of the discrete binarization sequence is 1 × 1.25=1.25hz, and if the discrete binarization sequence has eight pulses during the preset time period, the fluctuation frequency of the discrete binarization sequence is 8 × 1.25=10hz.

According to the embodiment of the present disclosure, in order to effectively distinguish between an encoder failure and an abnormal pitch (i.e., pitch motor forward-stop-reverse), an angle non-change counter, an angle up-counter, and an angle down-counter may be preset, and count values of the preset angle non-change counter, angle up-counter, and angle down-counter may be updated based on a blade angle value at each sampling time. In this case, it may be determined that the variable pitch system encoder fails in response to that the fluctuation frequency of the discrete binarization sequence is greater than a preset threshold value and that the count values of the angle no-change counter, the angle-up counter, and the angle-down counter satisfy a preset condition. Further, when the fluctuation frequency of the discrete binarization sequence is greater than a preset threshold value and the count values of the angle unchanged counter, the angle ascending counter and the angle descending counter meet preset conditions, it can be determined that an increment signal abnormal fault occurs in the variable pitch system encoder, and alarm information indicating that the increment signal is abnormal can be output. Here, the preset condition may include that the count value B of the angle up counter is greater than or equal to a difference between the number D of sampling times within the preset time period and the count value a of the angle unchanged counter, and the count value C of the angle down counter is zero (i.e., B ≧ D-a and C = 0); or the count value C of the angle down counter is greater than or equal to the difference between the number D of sampling moments in the preset time period and the count value A of the angle unchanged counter, and the count value of the angle up counter B is zero (i.e., C ≧ D-A and B = 0). Alternatively, the preset threshold may be set according to actual needs, for example, the preset threshold may be set in a range from 2Hz to 5Hz, but is not limited thereto. Generally, to effectively distinguish an encoder failure from a mechanical stuck condition, the preset threshold is generally not too low (e.g., not less than 2Hz, but not limited thereto).

According to an embodiment of the present disclosure, for the angle non-change counter, the count value of the angle non-change counter may be increased by 1 in response to the blade angle value at the present time being different from the angle value at the previous time, and the count value of the angle non-change counter may be maintained unchanged in response to the blade angle value at the present time being the same as the angle value at the previous time. For the angle up counter, the count value of the angle up counter may be increased by 1 in response to the vane angle value at the present time being greater than the angle value at the previous time, and the count value of the angle up counter may be maintained unchanged in response to the vane angle value at the present time being less than or equal to the angle value at the previous time. For the angle down counter, the count value of the angle down counter may be incremented by 1 in response to the vane angle value at the present time being less than the angle value at the previous time, and the count value of the angle down counter may be maintained unchanged in response to the vane angle value at the present time being greater than or equal to the angle value at the previous time. Alternatively, the count values of the angle no-change counter, the angle up counter, and the angle down counter may be cleared every time a preset time period starts.

According to the fault detection method of the encoder of the variable pitch system, whether the encoder breaks down or not can be directly judged only through the operation condition of the angle value of the blade, the method is suitable for variable pitch systems of various types, and has important significance for improving the fault elimination efficiency of the encoder and reducing the power generation loss. In addition, according to the fault detection method of the variable pitch system encoder, early warning of encoder faults can be achieved, therefore, open-loop feathering of the variable pitch system can be triggered in advance, and the condition that the angles of the three blades are unbalanced due to short-time blade clamping is prevented. In addition, according to the fault detection method of the variable pitch system encoder, the encoder fault can be effectively distinguished from the situations of mechanical clamping stagnation, given speed fluctuation and the like, so that the fault detection precision is improved.

Fig. 6 is a block diagram illustrating a controller according to an embodiment of the present disclosure. The controller according to embodiments of the present disclosure may be implemented as a pitch controller of a wind turbine generator system, as a main controller or other dedicated controller of the wind turbine generator system.

Referring to fig. 6, the controller 600 according to the present embodiment disclosure may include a processor 610 and a memory 620. The processor 610 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 620 may store computer programs to be executed by the processor 610. Memory 620 may include high speed random access memory and/or non-volatile computer-readable storage media. When the processor 610 executes the computer program stored in the memory 620, the wind-storage joint frequency modulation method as described above may be implemented.

Alternatively, the controller 600 may communicate with various other components in the integrated wind storage system in a wired/wireless communication manner, and may also communicate with other devices in the wind farm in a wired/wireless communication manner. Further, the controller 600 may communicate with a device external to the wind farm in a wired/wireless communication manner.

FIG. 7 is a diagram showing an application example of a fault detection method of a pitch system encoder according to an embodiment of the present disclosure.

Referring to fig. 7, the horizontal axis represents the number of scanning cycles. Curve 701 represents the leaf angle values and curve 702 represents the discrete binarization sequence generated based on the leaf angle values at each sampling instant, wherein TRUE represents a high level of 1 and false represents a low level of 0. As can be seen from fig. 7, the fluctuation frequency of the discrete binarization sequence (pulse signal) is high, and two groups of distinct pulse signals appear in succession. The curve 703 represents the fluctuation frequency of the discrete binarization sequence (pulse signal). As can be seen from fig. 7, the minimum frequency value is 8Hz, and the maximum frequency value is 18Hz, which are both greater than a preset threshold value (e.g., 5 Hz). A curve 704 represents the failure detection result of the encoder, in which the curve 704 is TRUE (high level 1) when the fluctuation frequency of the discrete binarization sequence (pulse signal) is (i.e., the encoder fails), and the curve 704 is FALSE (low level 0) when the encoder does not fail. As can be seen from fig. 7, according to the fault detection method for the encoder of the pitch system in the embodiment of the disclosure, an incremental signal abnormal fault occurring in the encoder can be accurately detected, and an early warning function is realized.

Further, when the fault detection method of the variable pitch system encoder detects that an incremental signal abnormal fault occurs in the encoder, the open-loop feathering of the variable pitch system can be triggered in advance, and the condition that the angles of the three blades are unbalanced due to short-time blade clamping is prevented.

FIG. 8 is a graph illustrating blade angle values that trigger pitch system open loop feathering when a pitch system encoder fails.

Referring to fig. 8, the abscissa represents time, and the ordinate represents a blade angle value, where time 0 is a time at which a fault is triggered (i.e., open-loop feathering is triggered), that is, time 0 is left and right blade angle values before and after the fault, respectively. As can be seen from fig. 8, at time 0, the blade angle value (curve 801) of the shaft with the encoder failed is stuck for a time of about 8 seconds before the open-loop feathering is started. During this time, since the other two blades normally perform the feathering, the angular difference of the three blades becomes larger and larger, causing the pneumatic unbalance of the wind turbine impeller (the angular difference of the three blades reaches 35 ° at maximum). However, according to the fault detection method for the encoder of the pitch system, the occurrence of the increment signal abnormal fault of the encoder can be accurately detected, and the sudden stop of the pitch driver is triggered, so that the pitch system enters an open-loop feathering state in advance, and the situations of She Pianka paddle and three-blade aerodynamic imbalance are prevented.

The fault detection method of a pitch system encoder according to embodiments 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 a method of fault detection for a pitch system encoder 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 + 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 Disk (SSD), card storage (such as a multimedia card, a Secure Digital (SD) card or an extreme digital (XD) card), a 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 any associated data, and to enable a computer program and any associated data processing or data structures to be executed by a computer. In one example, the computer program and any associated data, data files, and data structures are distributed across 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 fault detection method and the controller of the encoder of the variable pitch system, whether the encoder has a fault or not can be directly judged only through the operation condition of the angle value of the blade, the method and the controller are suitable for variable pitch systems of various types, and have important significance for improving the fault elimination efficiency of the encoder and reducing the power generation loss. In addition, according to the fault detection method and the controller of the variable pitch system encoder, early warning of encoder faults can be achieved, therefore, open-loop feathering of the variable pitch system can be triggered in advance, and the condition that the angles of the three blades are unbalanced due to short-time blade clamping is prevented. In addition, according to the fault detection method and the controller of the variable pitch system encoder, the encoder fault can be effectively distinguished from the conditions of mechanical clamping stagnation, given speed fluctuation and the like, so that the fault detection precision is improved.

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 (12)

1. A fault detection method for a pitch system encoder is characterized by comprising the following steps:

reading the angle value of the blade at each sampling moment in a preset time period of variable pitch operation;

generating a discrete binarization sequence based on the blade angle value at each sampling moment;

and in response to the preset time period expiring, determining whether a variable pitch system encoder fails or not based on the fluctuation frequency of the discrete binarization sequence.

2. The fault detection method of claim 1, wherein the fault detection method further comprises:

updating the count values of a preset angle unchanged counter, an angle ascending counter and an angle descending counter based on the blade angle value at each sampling moment,

the step of determining whether the variable pitch system encoder fails or not based on the fluctuation frequency of the discrete binarization sequence comprises the following steps of:

and determining that the variable pitch system encoder fails in response to the fact that the fluctuation frequency of the discrete binarization sequence is greater than a preset threshold value and the count values of the angle unchanged counter, the angle ascending counter and the angle descending counter meet preset conditions.

3. The fault detection method of claim 2, wherein the preset conditions include:

the count value of the angle rising counter is greater than or equal to the difference between the number of sampling moments in the preset time period and the count value of the angle unchanged counter, and the count value of the angle falling counter is zero; or

The count value of the angle down counter is greater than or equal to the difference between the number of sampling moments in the preset time period and the count value of the angle unchanged counter, and the count value of the angle up counter is zero.

4. The failure detection method according to claim 1, wherein the step of generating binarized discrete data based on the leaf angle value at each time comprises:

in response to the fact that the angle value of the blade at the current moment is different from the angle value at the previous moment, setting the position, corresponding to the current moment, in the discrete binarization sequence to be 1;

and in response to the blade angle value at the current moment being the same as the angle value at the previous moment, setting the position corresponding to the current moment in the discrete binarization sequence to be 0.

5. The fault detection method of claim 1, wherein the fault detection method further comprises:

reading a given pitch speed value at each moment in a preset time period,

the step of generating the binary discrete data based on the leaf angle value at each moment comprises the following steps:

in response to the difference between the angle value of the blade at the current moment and the angle value at the previous moment, setting the position corresponding to the current moment in the discrete binarization sequence to be 1;

in response to that the blade angle value at the current moment is the same as the angle value at the previous moment and the given variable pitch speed value at the current moment is not zero, setting the position corresponding to the current moment in the discrete binarization sequence to be 0;

and in response to that the blade angle value at the current moment is the same as the angle value at the previous moment and the given variable pitch speed value at the current moment is zero, setting the position corresponding to the current moment in the discrete binarization sequence as the value of the position corresponding to the previous moment.

6. The failure detection method according to claim 4 or 5, characterized in that the fluctuation frequency of the discrete binarization sequence is calculated based on the number of changes of 0 to 1 or the number of changes of 1 to 0 in the discrete binarization sequence and the duration of the preset time period.

7. The fault detection method according to claim 2, wherein the step of updating the count values of the preset angle no-change counter, angle-up counter and angle-down counter based on the blade angle value at each sampling timing comprises:

in response to the blade angle value at the current moment being different from the angle value at the previous moment, incrementing the count value of the angle-unchanged counter by 1, and in response to the blade angle value at the current moment being the same as the angle value at the previous moment, keeping the count value of the angle-unchanged counter unchanged;

increasing the count value of the angle increase counter by 1 in response to the blade angle value at the present time being greater than the angle value at the previous time, and maintaining the count value of the angle increase counter unchanged in response to the blade angle value at the present time being less than or equal to the angle value at the previous time;

the count value of the angle down counter is incremented by 1 in response to the vane angle value at the present time being less than the angle value at the previous time, and the count value of the angle down counter is maintained unchanged in response to the vane angle value at the present time being greater than or equal to the angle value at the previous time.

8. The failure detection method according to claim 2, wherein the count values of the angle no-change counter, the angle up counter, and the angle down counter are cleared in response to a start of the preset time period.

9. The fault detection method of claim 2, wherein the step of determining that a pitch system encoder is faulty comprises:

and determining that the incremental signal abnormal fault occurs in the variable pitch system encoder, and outputting alarm information indicating the incremental signal abnormal fault.

10. A computer-readable storage medium having stored thereon a computer program, characterized in that the computer program, when being executed by a processor, carries out a method of fault detection of a pitch system encoder according to any of claims 1 to 9.

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

a processor; and

a memory storing a computer program which, when executed by the processor, implements a method of fault detection of a pitch system encoder according to any of claims 1 to 9.

12. A wind park according to claim 11, wherein the wind park comprises a controller.

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