A wind turbine generator set pitch control system safety protection method

Abstract

The present invention discloses a safety protection method for a variable pitch system of a wind turbine generator set, comprising: the variable pitch system performs real-time detection of wind turbine operating data; the wind turbine operating data includes output current, blade angle, and current wind speed; the variable pitch driver determines whether the current state has entered a stuck blade safety protection mode based on the wind turbine operating data; the normal axis of the variable pitch system controls its blades to complete normal emergency retraction; the blade driver triggered by the stuck blade mode classifies the danger level of the current stuck blade operating condition based on the blade angle of the current faulty axis and the real-time wind speed; the driver adopts different fault reset control strategies according to the current operating condition level to drive the blades to complete emergency retraction. The present invention reduces the occurrence and danger level of single blade non-retraction events, thereby improving the safety of the unit.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine generator set control systems, and in particular to a safety protection method for a wind turbine generator set pitch control system. Background Art

[0002] As wind turbines become increasingly larger, their blades become increasingly slender. If a single blade fails to retract to a safe position during operation due to a jammed drive unit or pitch bearing, the risk to very large wind turbines increases significantly. Currently, when a single blade fails to retract, the pitch system typically controls the other two functioning blades to complete the retraction, leaving the faulty blade at its current angle. This prevents fatal damage to the pitch bearing, pitch gearbox, pitch motor, or drive on its axis, even if the motor and drive still have output capacity. Summary of the Invention

[0003] In response to the situation where a single blade cannot complete emergency retraction to a safe position due to reasons such as the drive unit or the pitch bearing being stuck, the present invention provides a safety protection method for the pitch system of a wind turbine generator set. According to different external environments and conditions, different emergency retraction level classification methods are adopted, so that when the environment is extremely harsh or dangerous, the pitch system can output the drive blades to complete the pitching as much as possible, avoid single blades from not retracting, and protect the safety of the unit; if the environment poses a very small safety risk to the wind turbine, then after several failed attempts to retract the blades, the pitch motor and driver belonging to the faulty shaft will shut down the output, turn off the motor brake, and stop at the current angle to avoid continuous output overload causing damage to the transmission shaft system or damage to the pitch motor and driver.

[0004] The present invention discloses a safety protection method for a wind turbine generator set pitch control system, which includes:

[0005] Step 1: The pitch control system performs real-time detection of wind turbine operating data, including output current, blade angle, and current wind speed.

[0006] Step 2: The pitch drive determines whether the current state has entered the stuck pitch safety protection mode based on the wind turbine operating data;

[0007] Step 3: The normal axis of the pitch system controls its blades to complete normal emergency retraction. The blade driver triggered by the stuck blade mode classifies the danger level of the current stuck blade condition based on the blade angle of the current faulty axis and the real-time wind speed.

[0008] Step 4: The driver adopts different fault reset control strategies according to the current operating condition level to drive the blades to complete emergency retraction.

[0009] Furthermore, the step 1 includes:

[0010] The inverter module built into the pitch drive controls and detects the output current of the drive in real time. The blade angle is fed back to the drive through the signal of the rotary transformer at the tail of the pitch motor. The pitch drive and pitch motor are electrically connected by cables. The wind speed data is measured by the wind measuring equipment and then transmitted to the wind turbine main control system. The wind turbine main control system divides the current wind speed into multiple intervals according to the preset threshold, converts it into a digital output signal, and transmits it to the DI signal terminal of the servo drive in the pitch system through the signal loop of the wind turbine's communication slip ring. The pitch drive parses the signal combination of the DI terminal into the corresponding wind speed interval in the pitch protection control algorithm according to the combination of the DI terminal.

[0011] Furthermore, the step 2 includes:

[0012] After entering the stuck blade safety protection mode, the wind turbine safety chain is disconnected and the other two blades are urgently retracted back to a safe position. For wind turbines, if a single blade is not retracted, the greater the wind speed at that time, the more dangerous it is; the number of wind speed segments is related to the number of signal input and output signals directly between the pitch control and the main control.

[0013] Furthermore, the step 2 includes:

[0014] If the motor brake is in the open state and the driver overload fault is triggered, and the angle change of the corresponding blade does not exceed the specified threshold within the statistical period, it is considered that the drive unit has failed or the bearing is stuck, and the propeller enters the stuck propeller safety protection mode.

[0015] Furthermore, the method for judging whether the driver is overloaded is that the current of the driver is greater than the set value within a continuous period of time. The set value is determined by the hardware of the servo driver. If the current is greater than the first specified value, the driver fault is immediately reported. If the current is less than the second specified value, the time for reporting the overload fault will increase accordingly, reflecting the accumulation of overcurrent within a certain period of time. After the driver reports the overload fault, the driver enters the self-protection state, turns off the output, and no longer drives the blades to adjust the angle.

[0016] Furthermore, the step 3 includes:

[0017] The blade to which the stuck blade belongs is divided into levels of emergency retraction of the pitch system in the control program of the pitch drive according to the current wind speed of the wind turbine and the angle of the faulty blade. The blade angle is divided into multiple intervals. For a wind turbine generator set, if a single blade is not retracted, the smaller the pitch angle, the more dangerous it is.

[0018] Furthermore, for wind turbines, if a single blade fails to retract, the greater the wind speed, the more dangerous it is. Based on the wind speed and angle conditions, emergency retraction levels are divided in the pitch drive control program, and different emergency retraction levels correspond to different reset strategies.

[0019] Furthermore, if the current shaft is in a Class I emergency retraction level operating condition, the driver will automatically reset the fault at certain intervals. After the driver meets the reset conditions and the fault is successfully reset, the driver and motor will drive the blades to feather within the set maximum capacity, regardless of whether an overload is reported again during the output process after the reset. Class I emergency retraction level operating conditions are the most dangerous.

[0020] Furthermore, if a mechanical component becomes stuck, the driver will report a fault again when the stuck propeller fault identification conditions are met. If the stuck mechanical component or the fault of the drive unit is temporary, the blades will be driven back to a safe position after the corresponding fault is reset; the mechanical components include pitch bearings and reducers.

[0021] Furthermore, if the current shaft is in a Class II emergency retraction level operating condition, the danger level is lower than that of a Class I emergency retraction level operating condition, and the driver uses the preset parameters in the program as the upper limit of the reset times Limit1 under this condition; that is, under the Class II emergency retraction level operating condition, after the driver meets the reset conditions and the fault is successfully reset, the driver and motor drive the blades to feather within the set maximum capacity range, and the accumulated number of faults reported by the driver before the limit switch is triggered is n. If n ≥ Limit1, the driver stops periodic resetting, turns off the output, turns off the motor brake, and the blades stop at the current position. The operation and maintenance personnel board the aircraft for inspection and maintenance.

[0022] Under each emergency propeller retraction level operating condition above Class II emergency propeller retraction level, there is a corresponding upper limit on the number of resets; the higher the emergency propeller retraction level, the greater the corresponding upper limit on the number of resets.

[0023] Due to the adoption of the above-mentioned technical solution, the present invention has the following advantages: when a blade is stuck or a drive unit fails, different control strategies can be adopted according to different external conditions to reduce the occurrence or degree of danger of a single blade not being retracted, thereby improving the safety of the unit; this solution does not rely on the information of the other two blades and the communication between the main control and the pitch control system. After adopting this solution in the three drivers, the implementation of the protection function can be completed independently. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments described in the embodiments of the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0025] Figure 1 Schematic diagram of a flow chart of a wind turbine generator set pitch control system safety protection method according to an embodiment of the present invention;

[0026] Figure 2 Schematic diagram of a pitch sticking protection system for a pitch control system according to an embodiment of the present invention;

[0027] Figure 3 The figure is a schematic diagram of the pitch sticking safety protection control flow of the pitch control system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The present invention will be further described with reference to the accompanying drawings and embodiments. The embodiments described are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by those skilled in the art should fall within the scope of protection of the embodiments of the present invention.

[0029] See also Figures 1 to 3 The present invention provides a wind turbine pitch system safety protection method, which detects the pitch system status in real time. If a drive unit or bearing stuck fault is identified, the method enters a pitch stuck safety protection mode. The specific steps are as follows:

[0030] S1, uses the pitch drive to perform real-time detection of key data such as output current, blade angle, and current wind speed;

[0031] S2: The internal propeller stuck recognition algorithm of the drive determines whether the current state has entered the propeller stuck safety protection mode;

[0032] In step S3, the other two normal axes of the pitch control system control their blades to complete normal emergency retraction. The internal stuck-pitch protection control algorithm of the blade driver triggered by the stuck-pitch mode classifies the emergency retraction condition according to the degree of danger based on the current blade angle of the faulty axis and the real-time wind speed.

[0033] S4: The internal stuck propeller protection control algorithm of the drive adopts different fault reset control strategies according to the current working condition level, and drives the blades to complete emergency retraction as much as possible.

[0034] In S1, the built-in inverter module of the pitch drive can control and detect the output current of the drive in real time. The blade angle is fed back to the drive through the signal of the rotary transformer at the tail of the pitch motor. The pitch drive and the pitch motor are electrically connected by cables. The wind speed data is measured by the wind measuring equipment and then transmitted to the wind turbine main control system. The wind turbine main control system divides the current wind speed into multiple intervals according to preset parameters, converts it into a digital output (DO) signal, and transmits it to the DI signal terminal of the servo drive in the pitch system through the signal loop of the wind turbine's communication slip ring. The pitch drive parses the signal combination of the DI terminal into the corresponding wind speed interval in the pitch protection control algorithm based on the combination of specific DI terminals.

[0035] In one embodiment, after entering the stuck blade safety protection mode, the wind turbine safety chain is disconnected and the other two blades are urgently retracted back to a safe position. Obviously, for a wind turbine generator set, if a single blade is not retracted, the greater the wind speed at that time, the more dangerous it is. The number of wind speed segments is related to the number of 24V signal input and output signals directly between the variable pitch and the main control. If the main control system and the variable pitch system are connected through two signal lines, such as Figure 2 As shown, the wind speed can be divided into 2 2 = 4 segments V1, V2, V3, V4. Obviously, if there are three signal connections, it can be divided into 2 3 =8 segments.

[0036] The reason for using a 24V hardware signal to transmit wind speed information is that if the wind speed information is transmitted to the main control system via CANOpen communication between the pitch control system and the main control system or other bus communication methods, in the event of a communication failure, the pitch control system will lose the wind speed information and will not be able to accurately classify the emergency pitch retraction level. However, the stability of the hard-wired signal is less affected by environmental and electromagnetic interference and has higher stability. Therefore, the wind speed information is measured by the anemometer and input into the main control system. The main control system controls the 24V DO (digital output) signal according to multiple threshold intervals V1...Vn, and connects it to the pitch control system through the hard wiring of the slip ring to ensure the stability of information transmission. The relationship between wind speed and DO signal is binary. For example, wind speeds greater than 25m / s are divided into the V1 interval, 15-25m / s are divided into the V2 interval, 8-15m / s are divided into the V3 interval, and less than 8m / s are divided into the V4 interval. In the main control system, the outputs of DO1 and DO2 are controlled in different wind speed intervals as shown in Table 1:

[0037] Table 1 Correspondence between different voltages and the outputs of DO1 and DO2

[0038] V1 V2 V3 V4 DO1 1 0 1 0 DO2 1 1 0 0

[0039] Similarly, on the driver side of the variable pitch system, the current wind speed range is obtained by looking up the table in the stuck pitch protection algorithm according to the received DI signal combination.

[0040] In one embodiment, the wind measuring equipment includes but is not limited to a mechanical anemometer and a laser anemometer.

[0041] In S2, the stuck propeller identification algorithm is characterized in that if the motor brake is in the open state AND the drive overload fault is triggered AND the angle change of the blade does not exceed a certain threshold within the statistical period, it is considered that the drive unit has failed or the bearing is stuck, and the stuck propeller safety protection mode is entered.

[0042] In one embodiment, the method for judging whether the driver is overloaded is that the driver current I2*t is greater than a set value. The size of the set value is determined by the hardware of the servo driver. If the current is very large, the driver fault will be reported quickly. If the current is relatively small, the time for reporting the overload fault will increase accordingly, reflecting the accumulation of overcurrent within a certain period of time. After the driver reports an overload fault, the driver will enter a self-protection state, turn off the output, and no longer drive the blade adjustment.

[0043] In S3, the blade to which the stuck propeller belongs is further divided into the emergency retraction level of the pitch system in the control program of the pitch drive according to the current wind speed of the wind turbine and the angle of the faulty blade. The blade angle can also be divided into multiple intervals α1..α m For wind turbines, if a single blade is not retracted, the smaller the pitch angle, the more dangerous it is.

[0044] In one embodiment, the current blade angle α<5° can be set to α1, 5°<α<10° can be set to α2, 10°<α<30° can be set to α3, and 30°<α can be set to α4.

[0045] For wind turbines, if a single blade fails to retract, the higher the wind speed, the more dangerous it is. Based on wind speed and angle conditions, the variable pitch drive control program can be divided into emergency retraction levels: I, II, III, IV... Different emergency retraction levels correspond to different reset strategies; I represents the most dangerous operating condition.

[0046] In one embodiment, the relationship between the emergency retraction level classification and the wind speed and blade angle is shown in Table 2:

[0047] Table 2 Relationship between emergency retraction level classification and wind speed and blade angle

[0048]

[0049]

[0050] For the different emergency propeller retraction levels in the above table, the propeller jam protection control algorithm in the drive will have corresponding control strategies.

[0051] In one embodiment, if the current shaft is in Class I operating conditions, the driver automatically resets the fault at regular intervals. After the driver meets the reset conditions and the fault is successfully reset, the driver and motor drive the blades to feather within the set maximum capacity range, regardless of whether overload is reported again during the output process after the reset.

[0052] In one embodiment, if a mechanical component such as a pitch bearing or reduction gearbox becomes stuck, the driver will report a fault again when the previously described pitch stuck fault identification conditions are met. If the mechanical component stuck or the drive unit failure is temporary, the blades can be smoothly driven back to a safe position after the corresponding fault is reset, thereby improving the safety of the unit. As long as the reset conditions are met, the driver will continue to reset, doing its best to drive the blades to retract until the drive unit is damaged or the limit is triggered. This sacrifices the safety of the pitch motor and driver in the pitch system to ensure the safety of the entire unit as much as possible.

[0053] In one embodiment, the reset period may be set to 10s;

[0054] If the current shaft is in Class II operating conditions, which are less dangerous than Class I conditions, the driver uses the preset parameters in the program as the upper limit of the number of resets under this condition, Limit1. That is, under Class II conditions, after the driver meets the reset conditions and the fault is successfully reset, the driver and motor drive the blades to feather within the set maximum capacity range, and accumulate the number of faults reported by the driver before the limit switch is triggered (returning to a safe position). If n ≥ Limit1, the driver stops periodic resets, turns off the output, closes the motor brake, and the associated blades stop at the current position. Operations and maintenance personnel then board the aircraft for inspection and maintenance.

[0055] Correspondingly, under Class III, IV... working conditions, there are respective upper limits on the number of resets, Limit2, Limit3...; obviously, Limit1>Limit2>Limit3.

[0056] In one embodiment, Limit1 may be set to 10, Limit2 may be set to 5, and Limit3 may be set to 3.

[0057] For the stuck propeller safety protection control algorithm, if the limit switch corresponding to the blade of the shaft to which it belongs is triggered or the operation and maintenance personnel board the aircraft for inspection, the variable pitch system will be switched to manual maintenance mode and then exit the stuck propeller safety protection mode.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A wind turbine pitch control system safety protection method, characterized in that: include: Step 1: The pitch control system performs real-time detection of wind turbine operating data, including output current, blade angle, and current wind speed. Step 2: The pitch drive determines whether the current state has entered the stuck pitch safety protection mode based on the wind turbine operating data; Step 3: The normal axis of the pitch system controls its blades to complete normal emergency retraction. The blade driver triggered by the stuck blade mode classifies the danger level of the current stuck blade condition based on the blade angle of the current faulty axis and the real-time wind speed. Step 4: The driver adopts different fault reset control strategies according to the current operating condition level to drive the blades to complete emergency retraction.

2. The method according to claim 1, characterized in that The step 1 comprises: The inverter module built into the pitch drive controls and detects the output current of the drive in real time. The blade angle is fed back to the drive through the signal of the rotary transformer at the tail of the pitch motor. The pitch drive and pitch motor are electrically connected by cables. The wind speed data is measured by the wind measuring equipment and then transmitted to the wind turbine main control system. The wind turbine main control system divides the current wind speed into multiple intervals according to the preset threshold, converts it into a digital output signal, and transmits it to the DI signal terminal of the servo drive in the pitch system through the signal loop of the wind turbine's communication slip ring. The pitch drive parses the signal combination of the DI terminal into the corresponding wind speed interval in the pitch protection control algorithm according to the combination of the DI terminal.

3. The method according to claim 1, characterized in that The step 2 includes: After entering the stuck blade safety protection mode, the wind turbine safety chain is disconnected and the other two blades are urgently retracted back to a safe position. For wind turbines, if a single blade is not retracted, the greater the wind speed at that time, the more dangerous it is; the number of wind speed segments is related to the number of signal input and output signals directly between the pitch control and the main control.

4. The method according to claim 1, wherein The step 2 includes: If the motor brake is in the open state and the driver overload fault is triggered, and the angle change of the corresponding blade does not exceed the specified threshold within the statistical period, it is considered that the drive unit has failed or the bearing is stuck, and the propeller enters the stuck propeller safety protection mode.

5. The method according to claim 4, characterized in that The method for judging whether the driver is overloaded is that the driver's current is greater than the set value for a sustained period of time. The set value is determined by the servo driver's hardware. If the current is greater than the first specified value, the driver fault is immediately reported. If the current is less than the second specified value, the time for reporting the overload fault will be increased accordingly, reflecting the accumulation of overcurrent within a certain period of time. After the driver reports an overload fault, it enters a self-protection state, shuts down the output, and no longer drives the blades to adjust the angle.

6. The method according to claim 1, characterized in that The step 3 comprises: The blade to which the stuck blade belongs is divided into levels of emergency retraction of the pitch system in the control program of the pitch drive according to the current wind speed of the wind turbine and the angle of the faulty blade. The blade angle is divided into multiple intervals. For a wind turbine generator set, if a single blade is not retracted, the smaller the pitch angle, the more dangerous it is.

7. The method according to claim 6, characterized in that For wind turbines, if a single blade fails to retract, the higher the wind speed, the more dangerous it is. Based on the wind speed and angle conditions, emergency retraction levels are divided in the pitch drive control program, and different emergency retraction levels correspond to different reset strategies.

8. The method according to claim 1, characterized in that If the current shaft is in a Class I emergency retraction level operating condition, the driver will automatically reset the fault at regular intervals. After the driver meets the reset conditions and the fault is successfully reset, the driver and motor will drive the blades to feather within the set maximum capacity, regardless of whether an overload is reported again during the output process after the reset. Class I emergency retraction level operating conditions are the most dangerous.

9. The method according to claim 1, characterized in that If a mechanical component is stuck, the driver will report the fault again when the stuck propeller fault identification conditions are met. If the stuck mechanical component or the drive unit fault is temporary, the blades will be driven back to a safe position after the corresponding fault is reset. The mechanical components include pitch bearings and reducers.

10. The method according to claim 1, characterized in that If the current axis is in the Class II emergency propeller retraction level working condition, the danger level is lower than that of the Class I emergency propeller retraction level working condition. The driver uses the preset parameters in the program as the upper limit of the reset number Limit1 under this working condition. That is, under the Class II emergency propeller retraction level working condition, after the driver meets the reset conditions and the fault is reset successfully, the driver and motor drive the blades to feather within the set maximum capacity range, and the number of faults reported by the driver is accumulated before the limit switch is triggered. If n ≥ Limit1, the driver stops periodic reset, turns off the output, turns off the motor brake, and the blades stop at the current position. The operation and maintenance personnel board the aircraft for inspection and maintenance. Under each emergency propeller retraction level above Class II emergency propeller retraction level, there is a corresponding upper limit on the number of resets; The higher the emergency propeller retraction level, the greater the upper limit of the corresponding reset times.

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