Safety protection method for variable pitch system of wind generating set

Abstract

The invention discloses a safety protection method for a variable-pitch system of a wind generating set. The safety protection method comprises the steps that the variable-pitch system detects operation data of a fan in real time; the fan operation data comprises output current, blade angle and current wind speed; the variable-pitch driver judges whether the current state enters a stuck-pitch safety protection mode or not according to the fan operation data; a normal shaft of the variable pitch system controls blades to which the normal shaft belongs to complete normal emergency pitch collection, and a blade driver triggered in a pitch clamping mode performs grade division on the danger degree of the current pitch clamping working condition according to the blade angle and the real-time wind speed of the current fault shaft; and the driver adopts different fault reset control strategies according to the current working condition grade so as to drive the blades to complete emergency blade retracting. According to the invention, the occurrence or danger degree of a single blade non-retracting event is reduced, and the safety of a unit is improved.

Description

Technical Field

[0001] The 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 the development of large-scale wind turbines continues to accelerate, wind turbine blades are becoming increasingly slender. If a single blade cannot be retracted to a safe position due to reasons such as the drive unit or pitch bearing being stuck during the operation of the wind turbine, the risk to super-large wind turbines will increase significantly. At present, when a single blade fails to retract, the pitch system usually controls the other two normal blades to complete the retraction, and the faulty blade stays at the current angle to avoid fatal damage to the pitch bearing, pitch reducer, pitch motor or driver of the shaft on which it is located. Even if the motor and driver still have output capacity, they will stay in the position. 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 a drive unit or a pitch bearing being stuck, the present invention provides a safety protection method for a pitch system of a wind turbine generator set. Different emergency retraction level classification methods are adopted according to different external environments and conditions. When the environment is extremely harsh or dangerous, the pitch system can output the drive blades to complete the pitch adjustment as much as possible to avoid a single blade not being retracted, thereby protecting the safety of the unit. If the environment poses little risk to the safety of the wind turbine, then after several failed attempts to retract the blades, the pitch motor and driver to which the faulty shaft belongs will shut down the output, turn off the motor brake, and stop at the current angle to avoid damage to the transmission shaft system or damage to the pitch motor and driver due to continuous output overload.

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

[0005] Step 1: The variable pitch system detects the wind turbine operating data in real time; the wind turbine operating data includes output current, blade angle and current wind speed;

[0006] Step 2: The pitch drive determines whether the current state enters the pitch stuck safety protection mode according to the wind turbine operation data;

[0007] Step 3: The normal axis of the pitch system controls the blades to which it belongs to complete normal emergency retraction, and the blade driver triggered by the stuck propeller mode grades the danger level of the current stuck propeller condition according to 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 comprises:

[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 through 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 stuck pitch protection control algorithm according to the combination of the DI terminal.

[0011] Furthermore, the step 2 comprises:

[0012] After entering the stuck propeller safety protection mode, the wind turbine safety chain is disconnected and the other two blades are urgently retracted back to a safe position. 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 signal input and output signals directly between the pitch control and the main control.

[0013] Furthermore, the step 2 comprises:

[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 stuck safety protection mode is entered.

[0015] Furthermore, the method for judging whether the driver is overloaded is that the current of the driver is greater than the set value for a sustained 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 an overload fault, the driver enters a self-protection state, turns off the output, and no longer drives the blades to adjust the angle.

[0016] Furthermore, the step 3 comprises:

[0017] The blade to which the stuck propeller 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 is not retracted, the greater the wind speed, the more dangerous it is. According to 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 drive the blades to straighten within the set maximum capacity range, 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 gets stuck, the driver will report a fault again when the stuck propeller fault identification conditions are met. If the jam of the 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 variable pitch bearings and reduction gearboxes.

[0021] Furthermore, if the current shaft is in a Class II emergency retraction level condition, the danger level is lower than that of a Class I emergency retraction level condition, and 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 the Class II emergency retraction level condition, after the driver meets the reset conditions and the fault is successfully reset, the driver and the motor drive the blades to feather within the set maximum capacity range, and the number of faults reported by the driver is n before the limit switch is triggered. 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, and the operation and maintenance personnel board the aircraft for inspection and maintenance;

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

[0023] Due to the adoption of the above-mentioned technical scheme, 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 retracting, thereby improving the safety of the unit; this scheme 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 scheme 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 drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded 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 A schematic 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 of a pitch system according to an embodiment of the present invention;

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

[0028] The present invention is further described in conjunction with the accompanying drawings and embodiments, and the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field 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 pitch system enters a pitch stuck safety protection mode. The specific steps are as follows:

[0030] S1, real-time detection of key data such as output current, blade angle, current wind speed, etc. through the variable pitch drive;

[0031] S2, the propeller stuck recognition algorithm inside the drive determines whether the current state enters the propeller stuck safety protection mode;

[0032] S3: The other two normal axes of the pitch system control their blades to complete normal emergency retraction. The internal pitch protection control algorithm of the blade driver triggered by the pitch mode divides the emergency retraction condition into different levels 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 propeller jam protection control algorithm of the drive adopts different fault reset control strategies according to the current working condition level to drive 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 through 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 stuck pitch protection control algorithm according to 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 24V hardware signal to transmit wind speed information is that if the wind speed information is transmitted through CANOpen communication between the variable pitch system and the main control system or other bus communication methods to the main control, in the case of communication failure, the variable pitch system will lose the wind speed information and cannot accurately divide the emergency pitch retraction level. The stability of the hard-wired signal is less affected by the environment and electromagnetic interference, and the stability is higher. Therefore, the wind speed information is measured by the anemometer to input the current wind speed into the main control system. The main control system controls the 24V DO (digital output) signal according to the multi-segment threshold interval V1...Vn, and connects to the variable pitch system through the hard wiring of the slip ring loop to ensure the stability of information transmission. The relationship between wind speed and DO signal is binary representation. For example, the wind speed greater than 25m / s is divided into the V1 interval, 15-25m / s is divided into the V2 interval, 8-15m / s is divided into the V3 interval, and less than 8m / s is divided into the V4 interval. In the main control system, in different wind speed intervals, the output of DO1 and DO2 is controlled 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 drive side of the variable pitch system, the current wind speed range is obtained by looking up a 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 driver 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 current I2*t of the driver is greater than the set value. The size of the set value is determined by the hardware of the servo driver. If the current is 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 blades for adjustment.

[0043] In S3, the blade to which the stuck propeller belongs is further divided into the 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 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 is not retracted, the greater the wind speed, the more dangerous it is. According to the wind speed and angle conditions, the emergency retraction levels can be divided into Ⅰ, Ⅱ, Ⅲ, Ⅳ... in the variable pitch drive control program. Different emergency retraction levels correspond to different reset strategies; Ⅰ represents the most dangerous working 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 the motor drive the blades to feather within the set maximum capacity range, regardless of whether an 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 a reduction gearbox is stuck, the driver will report a fault again when the previously described pitch fault identification conditions are met. If the mechanical component is stuck or the drive unit fails temporarily, 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 reset and do its best to drive the blades to retract until the drive unit is damaged or the limit is triggered, thereby ensuring the safety of the entire unit as much as possible by sacrificing the safety of the pitch motor and driver in the pitch system.

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

[0054] If the current shaft is in Class II working condition, the danger level is lower than that of Class I working condition, and the driver uses the preset parameters in the program as the upper limit of the reset times Limit1 under this working condition; that is, under Class II working condition, after the driver meets the reset conditions and the fault reset is successful, the driver and the motor drive the blades to feather within the set maximum capacity range, and accumulate the number of faults n reported by the driver before the limit switch is triggered (return to the safe position). 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;

[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 to which its axis 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 rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant 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 within 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 variable pitch system detects the wind turbine operating data in real time; the wind turbine operating data includes output current, blade angle and current wind speed; Step 2: The pitch drive determines whether the current state enters the pitch stuck safety protection mode according to the wind turbine operation data; Step 3: The normal axis of the pitch system controls the blades to which it belongs to complete normal emergency retraction, and the blade driver triggered by the stuck propeller mode grades the danger level of the current stuck propeller condition according to 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 through 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 stuck 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 comprises: After entering the stuck propeller safety protection mode, the wind turbine safety chain is disconnected and the other two blades are urgently retracted back to a safe position. 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 signal input and output signals directly between the pitch control and the main control.

4. The method according to claim 1, characterized in that: The step 2 comprises: 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 stuck safety protection mode is entered.

5. The method according to claim 4, characterized in that 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 an overload fault, the driver enters a self-protection state, turns off 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 propeller 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 is not retracted, the greater the wind speed, the more dangerous it is. According to 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 certain intervals. After the driver meets the reset conditions and the fault is successfully reset, the driver and motor will drive the blades to straighten 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 a 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. Mechanical components include pitch bearings and reduction gearboxes.

10. The method according to claim 1, characterized in that If the current axis is in the Class II emergency retraction level working condition, the danger level is lower than that of the Class I emergency retraction level working 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 working condition, after the driver meets the reset conditions and the fault reset is successful, the driver and the 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; Under each emergency propeller retraction level 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 upper limit of the corresponding reset times.

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