A Fault Detection Device and Method for the Yaw System of a Wind Turbine

Abstract

The present invention discloses a yaw system fault detection device and method for a wind turbine. The device includes a signal acquisition module and a signal processing and fault diagnosis module. The signal acquisition module obtains the nacelle yaw status information and environmental status information of the wind turbine. The signal processing and fault diagnosis module includes a yaw frequency converter and a main control PLC unit capable of data interaction. The main control PLC unit is data-connected to the signal acquisition module, receives the environmental status information and the nacelle yaw status information to perform non-motor type fault detection. The yaw frequency converter performs motor type fault detection. Through the above detection device, the collection of the three-phase current of the yaw motor, the motor temperature, and the brake feedback signal can be realized, the collection of information such as yaw cable twisting, hydraulic pressure, wind speed and direction, and yaw vibration transmission can be realized, and through information processing, the fault diagnosis of the yaw system can be realized, and the accurate positioning of the motor fault can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power equipment detection, and particularly relates to a yaw system fault detection device and method for a wind turbine generator set. Background Art

[0002] As an important part of a wind turbine generator, the yaw system is used to receive commands from the main control system, control the nacelle to rotate to a set position, align the unit with the wind, and enable the wind turbine to track the changing and stable wind direction. At the same time, when the cable led out inside the nacelle is wound due to the yaw action of the wind turbine generator set, the automatic unwinding function can be realized.

[0003] The yaw system mainly consists of components such as a hydraulic system, a yaw motor, a yaw driver, a yaw reduction gearbox, and a yaw bearing. Since there are many components in the yaw system, when a fault occurs in the yaw system, it cannot be detected or accurately located in time. The unit will stop for a long time, reducing the power generation of the unit. Seriously, it may cause serious damage to components of the yaw system such as broken teeth on the yaw bearing gear ring and wear and fracture of the yaw brake disc.

[0004] In the prior art, on the one hand, various parameters of the yaw system can be collected through an on-line monitoring mechanism of the yaw system of the wind turbine generator set, the original data can be screened, and the screened data can be modeled and analyzed using the support vector machine algorithm. According to the fault diagnosis and life assessment methods, the fault diagnosis result can be obtained. The disadvantage of the above method is that the algorithm is too complex. On the other hand, the monitoring data collected in the yaw system can be obtained, and the monitoring data can be input into the yaw fault diagnosis model to output the fault diagnosis result. Among them, the fault diagnosis model is obtained by training with known fault diagnosis results and corresponding monitoring data. The monitoring data collected by the yaw system is input into the yaw fault diagnosis model in real time, and the yaw fault diagnosis model is used to determine whether a fault occurs in the yaw system and the specific fault diagnosis result when a fault occurs. However, the above method is for the judgment of the yaw system fault under the hard start control of the yaw motor, and is not applicable to the system fault judgment of the yaw frequency converter scheme, especially the one-to-many yaw motor scheme. At the same time, it is also impossible to accurately locate which motor in the yaw system has a fault. Summary of the Invention

[0005] The purpose of the embodiments of the present invention is to provide a yaw system fault detection device and method for a wind turbine generator set. Through the above detection device, the three-phase current, motor temperature, and brake feedback signal of the yaw motor can be collected, the information such as yaw cable twisting, hydraulic pressure, wind speed and direction, and yaw vibration transmission can be collected, and through information processing, the yaw system fault diagnosis can be realized, and the accurate positioning of the motor fault can be realized.

[0006] To solve the above technical problems, a first aspect of an embodiment of the present invention provides a yaw system fault detection device for a wind turbine, including: a signal acquisition module and a signal processing and fault diagnosis module;

[0007] The signal acquisition module acquires the nacelle yaw state information and the environmental state information of the wind turbine;

[0008] The signal processing and fault diagnosis module includes: a yaw frequency converter and a main control PLC unit capable of data interaction;

[0009] The main control PLC unit is data-connected to the signal acquisition module, and receives the environmental state information and the nacelle yaw state information to perform non-motor type fault detection;

[0010] The yaw frequency converter performs motor type fault detection.

[0011] Further, the signal acquisition module includes: a yaw twist cable encoder, a hydraulic pressure sensor, a wind speed and direction sensor, a yaw vibration sensor, and a motor current acquisition sensor, which are respectively connected to the signal processing and fault diagnosis module;

[0012] The yaw twist cable encoder is used to collect the angle of the nacelle yaw of the wind turbine;

[0013] The hydraulic pressure sensor is used to collect the pressure change during the yaw process of the yaw hydraulic system of the wind turbine;

[0014] The wind speed and direction sensor is used to collect the real-time wind speed and direction of the environment of the wind turbine;

[0015] The yaw vibration sensor is used to collect the vibration condition of the yaw speed reducer of the wind turbine;

[0016] The motor current acquisition sensor is used to collect the current of each motor branch of the wind turbine.

[0017] Further, the yaw frequency converter performs fault diagnosis on the yaw motor, mainly including: electric brake failure, motor overheating failure, motor blockage and current imbalance failure.

[0018] Further, the environmental state information includes: the wind speed and direction of the environment where the wind turbine is located, and the nacelle yaw state information includes: the angle of the nacelle, the hydraulic pressure, the vibration signal of the speed reducer, and the status word and fault word of the yaw driver;

[0019] The non-motor type fault detection performed by the main control PLC unit mainly includes: yaw twist cable fault, hydraulic pressure abnormal fault, speed reducer abnormal fault and yaw driver fault.

[0020] Further, the yaw frequency converter and the main control PLC unit perform data interaction through CAN communication.

[0021] Correspondingly, a second aspect of the embodiments of the present invention further provides a method for detecting faults in a yaw system of a wind turbine. Based on a fault detection device for the yaw system of the wind turbine, the method for detecting faults in the yaw system of the wind turbine includes the following steps:

[0022] Based on the main control PLC unit, it is determined in real time whether there are yaw faults related to yaw;

[0023] Classify the yaw faults and determine the fault types of the yaw faults;

[0024] When the yaw fault is a motor - type fault, the specific fault type is determined by viewing the fault word corresponding to the data communication. The specific fault types of the motor - type faults include: electric brake fault, motor over - temperature fault, motor blocked - rotor, and motor current imbalance fault;

[0025] When the yaw fault is a non - motor - type fault, the specific fault type of the yaw device is determined based on the yaw state information of the nacelle and the environmental state information. The specific fault types of the yaw device include: yaw cable - twisting fault, abnormal yaw hydraulic pressure fault, abnormal gearbox fault, and yaw driver fault.

[0026] Further, the detection condition for the electric brake fault is as follows: when the yaw brake is not opened, the internal contact of the brake is disconnected, and the low level is output to the corresponding channel of the driver 24VDI; when the yaw brake is opened, the internal contact of the brake is closed, and the high level is output to the corresponding channel of the driver 24VDI; when the 24VDI levels of the yaw brake action and feedback are inconsistent, it is determined that there is an electric brake fault;

[0027] The diagnosis condition for the motor over - temperature fault is: when the temperature value corresponding to the PTC resistor buried inside the motor detected by the analog - quantity detection channel of the yaw driver is greater than 130 °C, it is determined that there is a motor over - temperature fault;

[0028] The diagnosis condition for the motor blocked - rotor is: when the total output current of the motor exceeds the current value set by the driver, it is determined that there is a motor blocked - rotor fault;

[0029] The diagnosis condition for the motor current imbalance fault is: the yaw driver compares the effective values of the motor phase - sequence currents collected. If the deviation of a certain motor phase - sequence current from the average value of all motor phase - sequence currents exceeds the set value, it is determined that the current of a certain phase of the motor is unbalanced.

[0030] Further, the diagnosis condition for the yaw cable - twisting fault is: when the main control PLC detects that the cable - twisting signal output by the yaw cable - twisting encoder is at a high level, it is determined that there is a yaw cable - twisting fault; and / or

[0031] The diagnostic conditions for the abnormal yaw hydraulic pressure fault are as follows: when the unit stops yawing, the main control PLC collects that the hydraulic pressure exceeds the set value of the stop pressure deviation; or when the unit is yawing, the main control PLC collects that the hydraulic pressure exceeds the set value of the running pressure deviation, in which case it is determined that there is an abnormal yaw hydraulic pressure fault;

[0032] The diagnostic conditions for the abnormal speed reducer fault are as follows: when the main control PLC collects that the vibration signal of the yaw speed reducer exceeds the set value, it is determined that there is an abnormal speed reducer fault;

[0033] The diagnostic conditions for the yaw drive fault are as follows: when a fault occurs inside the yaw drive, the corresponding fault bit will be set. When the main control PLC detects through CAN communication that the fault position corresponding to the yaw drive fault word is set, it is determined that there is a yaw drive fault.

[0034] The above technical solutions of the embodiments of the present invention have the following beneficial technical effects:

[0035] Through the above detection device, the three-phase current, motor temperature, and brake feedback signal of the yaw motor can be collected, the information such as yaw cable twisting, hydraulic pressure, wind speed and direction, and yaw vibration transmission can be collected, and through information processing, the fault diagnosis of the yaw system can be realized, and the accurate positioning of the motor fault can be realized. Description of the Drawings

[0036] Figure 1 is a schematic diagram of the composition of the yaw system fault detection device for a wind turbine provided by an embodiment of the present invention;

[0037] Figure 2 is a schematic diagram of the single-motor type fault detection provided by an embodiment of the present invention;

[0038] Figure 3 is a schematic diagram of the yaw system fault detection flow provided by an embodiment of the present invention;

[0039] Figure 4 is a schematic diagram of the fault code provided by an embodiment of the present invention. Detailed Embodiments

[0040] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0041] Please refer to Figure 1 、 Figure 2 and Figure 3, in the first aspect of the embodiment of the present invention, a yaw system fault detection device for a wind turbine is provided, including: a signal acquisition module and a signal processing and fault diagnosis module; the signal acquisition module acquires the nacelle yaw state information and environmental state information of the wind turbine; the signal processing and fault diagnosis module includes: a yaw frequency converter and a main control PLC unit capable of data interaction; the main control PLC unit is data-connected to the signal acquisition module, receives the environmental state information and the nacelle yaw state information to perform non-motor type fault detection; the yaw frequency converter performs motor type fault detection.

[0042] Further, the signal acquisition module includes: a yaw cable twisting encoder, a hydraulic pressure sensor, a wind speed and direction sensor, a yaw vibration sensor, and / or a motor current acquisition sensor respectively connected to the signal processing and fault diagnosis module; the yaw cable twisting encoder is used to collect the yaw angle of the wind turbine nacelle; the hydraulic pressure sensor is used to collect the pressure change during the yaw process of the wind turbine yaw hydraulic system; the wind speed and direction sensor is used to collect the real-time wind speed and direction of the wind turbine environment; the yaw vibration sensor is used to collect the vibration condition of the wind turbine yaw speed reducer; the motor current acquisition sensor is used to collect the current of each motor branch of the wind turbine.

[0043] Further, the yaw frequency converter performs fault diagnosis on the yaw motor, mainly including: brake failure of the motor, over-temperature failure of the motor, motor blockage and current imbalance failure.

[0044] Further, the environmental state information includes: the wind speed and direction of the environment where the wind turbine is located, and the nacelle yaw state information includes: the angle of the nacelle, the hydraulic pressure, the vibration signal of the speed reducer, and the status word and fault word of the yaw driver; the non-motor type fault detection performed by the main control PLC unit mainly includes: yaw cable twisting fault, abnormal hydraulic pressure fault, abnormal speed reducer fault, and yaw driver fault.

[0045] Further, the yaw frequency converter and the main control PLC unit perform data interaction through CAN communication.

[0046] Specifically, as an important part of the wind turbine, the yaw system, in addition to realizing the wind control of the unit and the functions of cable twisting and untwisting, also needs to have the function of diagnosing and detecting its own faults, so as to quickly troubleshoot the yaw faults that occur and ensure the power generation efficiency of the unit. The following takes a 2.XMW unit with 4 yaw motors as an example for illustration.

[0047] The system composition of the yaw system fault detection device is as Figure 1As shown in the figure, the master PLC realizes information interaction with the yaw frequency converter through the CAN communication line, and issues start / stop, yaw drive fault reset commands and motor speed commands to the yaw frequency converter through the control word; the yaw frequency converter uploads the temperature of the frequency converter, actual speed, actual torque, active power, status word and fault word to the master PLC, where the status word includes yaw start / stop, motor rotation direction, brake status, and speed status; the fault word includes yaw frequency converter itself faults, yaw motor PTC abnormalities, motor brake braking circuit faults, motor overheating, overload, current imbalance, etc. When the PLC detects the position 1 of the fault word, it reports a yaw motor type fault, and confirms which specific fault it is by viewing the fault word corresponding to the CAN communication. If bit5 of the fault word is 1, it is a yaw motor PTC abnormality, corresponding to Figure 4 fault code 0301 in; if bit10 of the fault word is 1, it is a motor braking circuit fault, corresponding to Figure 4 fault code 0302 in; if bit13 of the fault word is 1, it is a yaw motor overheating, corresponding to Figure 4 fault code 0303 in; if bit14 of the fault word is 1, it is a yaw motor stall, corresponding to Figure 4 fault code 0304 in; if bit15 of the fault word is 1, it is a yaw motor current imbalance fault, corresponding to Figure 4 fault code 0305 in.

[0048] The judgment condition of the motor brake fault bit10 is as follows: Select a 24V signal to serially connect the brake contacts of 4 motors, and connect the final output signal to the driver 24VDI7 channel. The driver 24VDO4 turns on to control the yaw brake power supply relay of 4 yaw motors, as Figure 2 shown. When the master does not issue a yaw start command and the driver DO4 turns on 0, the yaw brake power supply relay is disconnected at this time, the brake is not powered, the internal contacts of the brake are disconnected, and DI7 is 0; on the contrary, when the driver DO4 turns on 1, the yaw brake power supply relay is closed at this time, the brake is powered, the internal contacts of the brake are closed, and DI7 is 1. When the action of the yaw brake control DO4 and the feedback DI7 are inconsistent, it is determined that the motor brake is faulty, that is, bit10 is 1;

[0049] The judgment condition of the motor overheating fault bit13 is as follows: When the yaw driver analog detection channel detects that the temperature value corresponding to the PTC resistor buried inside each motor is greater than 130 °C, it is determined that the motor overheating fault, that is, bit13 is 1, as Figure 2 shown.

[0050] The judgment condition of the motor stall bit14 is as follows: When the total output current of the motor exceeds the current value set by the driver, it is determined that the motor is stalled.

[0051] The diagnostic condition for the motor current imbalance bit15 is as follows: The yaw drive compares the effective values of the motor U, V, and W phase currents collected. If the deviation of the U-phase current of a certain motor from the average value of the 12-phase currents of 4 motors exceeds the set value of 1.5 A, it is determined that the U-phase current of this motor is unbalanced; the collection of the 3-phase current of the yaw motor is as Figure 2 shown.

[0052] The system composition of the yaw system fault detection device is as Figure 1 shown. The main control PLC collects the wind speed and wind direction information collected by the wind speed and wind direction sensors through RS485 communication, and transmits the pressure signal of the hydraulic system collected by the pressure sensor and the acceleration signal of the yaw reduction gearbox collected by the vibration sensor to the PLC for calculation through the analog acquisition module X20AI4622; the yaw signal of the torsion cable encoder is collected through the digital quantity DI input module X20DI9371; the speed ABZ pulse signal of the yaw gear ring measured by the torsion cable encoder is collected through the digital pulse acquisition module X20DC137A to calculate the yaw speed. By collecting the above signals, the yaw-related torsion cable fault, hydraulic pressure abnormal fault, reduction gearbox abnormal fault, and yaw drive fault are judged.

[0053] The judgment condition for the yaw torsion cable fault is: when the main control PLC digital quantity DI input module X20DI9371 detects that the yaw signal output by the yaw torsion cable encoder is at a high level, it is determined that the yaw torsion cable fault, corresponding to Figure 4 fault code 0306;

[0054] The judgment condition for the yaw hydraulic pressure abnormal fault is: when the unit stops yawing, when the main control PLC analog acquisition module X20AI4622 collects that the hydraulic pressure exceeds the stop pressure range of (160 ± 15) bar; or when the unit is yawing, when the main control PLC collects that the hydraulic pressure exceeds the operating pressure range of (30 ± 10) bar, it is determined that the yaw hydraulic pressure abnormal fault, corresponding to Figure 4 fault code 0307;

[0055] The judgment condition for the reduction gearbox abnormal fault is: when the main control PLC collects that the acceleration signal of the yaw reduction gearbox exceeds the set value, it is determined that the reduction gearbox abnormal fault, corresponding to Figure 4 fault code 0308;

[0056] The judgment condition for the yaw drive fault is: when the main control PLC detects that the fault bit corresponding to the yaw drive fault word is set through CAN communication, it is determined that the yaw drive fault, corresponding to Figure 4 fault code 0309.

[0057] Correspondingly, a second aspect of the embodiments of the present invention further provides a method for detecting faults in a yaw system of a wind turbine, which performs fault detection on the yaw system of the wind turbine based on a fault detection device for the yaw system of the wind turbine, and includes the following steps:

[0058] Based on the master control PLC unit, it is determined in real time whether there are yaw faults related to yaw;

[0059] Classify the yaw faults and determine the fault types of the yaw faults;

[0060] When the yaw fault is a motor - type fault, the specific fault type is determined by viewing the fault word corresponding to the data communication. The specific fault types of the motor - type faults include: brake failure of the motor, over - temperature failure of the motor, motor stalling, and unbalanced motor current failure;

[0061] When the yaw fault is a non - motor - type fault, the specific fault type of the yaw equipment is determined based on the yaw state information of the nacelle and the environmental state information. The specific fault types of the yaw equipment include: yaw cable - twisting fault, abnormal yaw hydraulic pressure fault, abnormal gearbox fault, and yaw driver fault.

[0062] Furthermore, the detection condition for the brake failure of the motor is as follows: when the yaw brake is not opened, the internal contact of the brake is disconnected, and a low level is output to the corresponding channel of the 24VDI of the driver; when the yaw brake is opened, the internal contact of the brake is closed, and a high level is output to the corresponding channel of the 24VDI of the driver; when the 24VDI levels of the yaw brake action and feedback are inconsistent, it is determined that there is a brake failure of the motor;

[0063] The diagnosis condition for the over - temperature failure of the motor is: when the temperature value corresponding to the PTC resistor buried inside the motor detected by the analog - quantity detection channel of the yaw driver is greater than 130°C, it is determined that there is an over - temperature failure of the motor;

[0064] The diagnosis condition for motor stalling is: when the total output current of the motor exceeds the current value set by the driver, it is determined that there is a motor stalling fault;

[0065] The diagnosis condition for the unbalanced motor current failure is: the yaw driver compares the effective values of the motor phase - sequence currents collected. If the deviation of a certain motor phase - sequence current from the average value of all motor phase - sequence currents exceeds the set value, it is determined that the current of a certain phase of the motor is unbalanced.

[0066] Furthermore, the diagnosis condition for the yaw cable - twisting fault is: when the master control PLC detects that the cable - twisting signal output by the yaw cable - twisting encoder is at a high level, it is determined that there is a yaw cable - twisting fault;

[0067] The diagnostic conditions for abnormal yaw hydraulic pressure faults are as follows: when the unit stops yawing, if the main control PLC detects that the hydraulic pressure exceeds the set value of the stop pressure deviation; or when the unit is yawing, if the main control PLC detects that the hydraulic pressure exceeds the set value of the operating pressure deviation, it is determined that there is an abnormal yaw hydraulic pressure fault;

[0068] The diagnostic conditions for abnormal faults in the speed reducer are as follows: when the main control PLC detects that the vibration signal of the yaw speed reducer exceeds the set value, it is determined that there is an abnormal fault in the speed reducer;

[0069] The diagnostic conditions for yaw drive faults are as follows: when a fault occurs inside the yaw drive, the corresponding fault bit will be set. When the main control PLC detects through CAN communication that the fault position corresponding to the fault word of the yaw drive is set, it is determined that there is a yaw drive fault.

[0070] The embodiments of the present invention aim to protect a yaw system fault detection device and method for a wind turbine, with the following effects:

[0071] Through the above detection device, it is possible to collect the three-phase current, motor temperature, and brake feedback signal of the yaw motor, collect information such as yaw cable twisting, hydraulic pressure, wind speed and direction, and yaw vibration transmission, and through information processing, it is possible to achieve yaw system fault diagnosis and accurate positioning of motor faults.

[0072] It should be understood that the above specific embodiments of the present invention are only used for exemplary illustration or explanation of the principle of the present invention, and do not constitute a limitation to the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and scope of the present invention shall be included within the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundary of the appended claims, or equivalent forms of such scope and boundary.

Claims

1. A yaw system fault detection device for a wind turbine, characterized in that Comprising: A signal acquisition module and a signal processing and fault diagnosis module; The signal acquisition module acquires the nacelle yaw state information and environmental state information of the wind turbine; The signal processing and fault diagnosis module includes: a yaw frequency converter and a main control PLC unit capable of data interaction; The main control PLC unit is data-connected to the signal acquisition module, receives the environmental state information and the nacelle yaw state information to perform non-motor type fault detection; The yaw frequency converter performs motor type fault detection, and the yaw frequency converter performs fault diagnosis on the yaw motor, including: electric brake fault, motor over-temperature fault, motor blocked rotation and current imbalance fault.

2. The wind turbine yaw system fault detection device according to claim 1, wherein The signal acquisition module includes: a yaw cable twisting encoder, a hydraulic pressure sensor, a wind speed and direction sensor, a yaw vibration sensor, and a motor current acquisition sensor respectively connected to the signal processing and fault diagnosis module; The yaw cable twisting encoder is used to collect the yaw angle of the nacelle of the wind turbine; The hydraulic pressure sensor is used to collect the pressure change during the yaw process of the yaw hydraulic system of the wind turbine; The wind speed and direction sensor is used to collect the real-time wind speed and direction of the environment of the wind turbine; The yaw vibration sensor is used to collect the vibration condition of the yaw reduction gearbox of the wind turbine; The motor current acquisition sensor is used to collect the current of each motor branch of the wind turbine.

3. The wind turbine yaw system fault detection device according to claim 1, wherein The environmental state information includes: the wind speed and direction of the environment where the wind turbine is located, and the nacelle yaw state information includes: the angle of the nacelle, hydraulic pressure, vibration signal of the reduction gearbox, and status word and fault word of the yaw driver; The non-motor type fault detection performed by the main control PLC unit mainly includes: yaw cable twisting fault, abnormal hydraulic pressure fault, abnormal reduction gearbox fault, and yaw driver fault.

4. The wind turbine yaw system fault detection device according to any one of claims 1-3, wherein The yaw frequency converter and the main control PLC unit perform data interaction through CAN communication.

5. A yaw system fault detection method for a wind turbine, characterized in that Based on the wind turbine yaw system fault detection device according to any one of claims 1-4, the fault detection of the wind turbine yaw system includes the following steps: Based on the main control PLC unit, it is determined in real time whether there is a yaw-related yaw fault; Classify the yaw fault and judge the fault type of the yaw fault; When the yaw fault is a motor type fault, the specific fault type is determined by checking the fault word corresponding to the data communication. The specific fault types of the motor type fault include: electric brake fault, motor over-temperature fault, motor blocked rotation and motor current imbalance fault; When the yaw fault is a non-motor type fault, the specific fault type of the yaw device is judged based on the nacelle yaw state information and the environmental state information. The specific fault types of the yaw device include: yaw cable twisting fault, abnormal yaw hydraulic pressure fault, abnormal reduction gearbox fault, and yaw driver fault.

6. The fault detection method for the yaw system of a wind turbine according to claim 5, wherein: The detection condition for the electric motor brake fault is as follows: when the yaw brake is not opened, the internal contact of the brake is disconnected, and a low level is output to the corresponding channel of the driver 24VDI; when the yaw brake is opened, the internal contact of the brake is closed, and a high level is output to the corresponding channel of the driver 24VDI; when the 24VDI levels of the yaw brake action and feedback are inconsistent, it is determined that the electric motor brake is faulty; The diagnostic condition for the electric motor overheating fault is as follows: when the temperature value corresponding to the PTC resistor buried inside the motor detected by the analog detection channel of the yaw driver is greater than 130 °C, it is determined that the electric motor overheating fault occurs; The diagnostic condition for the electric motor blocked rotation is as follows: when the total output current of the motor exceeds the current value set by the driver, it is determined that the electric motor blocked rotation fault occurs; The diagnostic condition for the electric motor current imbalance fault is as follows: the yaw driver compares the effective values of the motor phase sequence currents collected. If the deviation of a certain motor phase sequence current from the average value of all motor phase sequence currents exceeds the set value, it is determined that the current of a certain phase of the motor is unbalanced.

7. The fault detection method for the yaw system of a wind turbine according to claim 6, wherein: The diagnostic condition for the yaw cable twisting fault is as follows: when the main control PLC detects that the cable twisting signal output by the yaw cable twisting encoder is at a high level, it is determined that the yaw cable twisting fault occurs; The diagnostic condition for the abnormal yaw hydraulic pressure fault is as follows: when the unit stops yawing, the main control PLC collects that the hydraulic pressure exceeds the set value of the stop pressure deviation; or when the unit is yawing, the main control PLC collects that the hydraulic pressure exceeds the set value of the operating pressure deviation, and it is determined that the abnormal yaw hydraulic pressure fault occurs; The diagnostic condition for the abnormal reduction gearbox fault is as follows: when the main control PLC collects that the vibration signal of the yaw reduction gearbox exceeds the set value, it is determined that the reduction gearbox is abnormally faulty; The diagnostic condition for the yaw driver fault is as follows: when a fault occurs inside the yaw driver, the corresponding fault bit is set. When the main control PLC detects through CAN communication that the fault position corresponding to the fault word of the yaw driver is set, it is determined that the yaw driver is faulty.

Images