Fault detection system and method for operation condition of yaw transmission system of wind driven generator

Abstract

The invention provides a fault detection system and method for the operation condition of a yaw transmission system of a wind driven generator. The fault detection system comprises a system control module, a torque detection module, a temperature detection module and an early warning module. The torque detection module is used for detecting the torque magnitude and direction of the output main shaft and each input shaft of the yaw transmission system; the temperature detection module is used for detecting the temperature of each driving motor of the yaw transmission system and the environment temperature in a cabin of the wind driven generator; the system control module performs information interaction with the torque detection module, the temperature detection module and the early warning module, and is used for processing torque and temperature information collected by the torque detection module and the temperature detection module, judging whether an abnormal condition exists or not and obtaining a performance index value; and the working state of the yaw transmission system is detected according to the fault data model, and a processing result is transmitted to the early warning module to be output.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine fault detection, and in particular to a fault detection system and method for the operating condition of a yaw transmission system of a wind turbine. Background Art

[0002] With the development of wind power generation technology, wind power generation has become the main form of renewable energy generation. Large wind turbines have complex structures and are typical of large rotating mechanical equipment. Wind power plants are often built in remote areas, and their operation is easily affected by the environment. They have a high failure rate and a variety of failure mechanisms. Compared with conventional equipment, it is more difficult to identify changes in the operating state of wind turbines due to the randomness of wind. Once a wind turbine fails, it can cause grid fluctuations and affect the quality of power generation. In severe cases, it can cause grid failures, power failure, and safety accidents.

[0003] At the same time, the yaw system of modern large wind turbines is located at the top of the tower, and the maintenance and replacement process is complicated, making operation and maintenance difficult. However, there is currently no specific fault detection solution for the yaw system in existing wind turbines. Summary of the invention

[0004] In order to solve the problem that the yaw system of existing modern large wind turbines is located at the top of the tower, the maintenance and replacement process is complicated, and the operation and maintenance are difficult, the present invention provides a fault detection system and detection method for detecting the operating status of the yaw transmission system of a wind turbine based on torque and temperature measurement, which provides a solution for fault detection of the yaw system and can solve the problem of detecting the working status of the motor and main transmission components of the yaw transmission system of the wind turbine.

[0005] The fault detection system for the operating status of the yaw transmission system of a wind turbine provided by it includes: a system control module, a torque detection module, a temperature detection module, and an early warning module; wherein the torque detection module is used to detect the torque of the output main shaft and each input shaft of the yaw transmission system; the temperature detection module is used to detect the temperature of each drive motor of the yaw transmission system; the system control module exchanges information with the torque detection module, the temperature detection module, and the early warning module, the system control module processes the torque and temperature information collected by the torque detection module and the temperature detection module, and transmits the processing results to the early warning module, and the early warning module outputs the processing results, which provides a solution for the fault detection of the yaw system and can detect problems with the working status of the motor and main transmission components of the yaw transmission system of the wind turbine.

[0006] The present invention specifically adopts the following technical solutions:

[0007] A fault detection system for the operating status of a yaw transmission system of a wind turbine:

[0008] Including: system control module, torque detection module, temperature detection module and early warning module;

[0009] The torque detection module is used to detect the torque magnitude and direction of the output main shaft and each input shaft of the yaw transmission system;

[0010] The temperature detection module is used to detect the temperature of each drive motor of the yaw transmission system and the ambient temperature in the wind turbine cabin;

[0011] The system control module exchanges information with the torque detection module, the temperature detection module, and the early warning module to process the torque and temperature information collected by the torque detection module and the temperature detection module, determine whether there is an abnormal situation, and obtain performance index values; detect the working status of the yaw transmission system according to the fault data model, and transmit the processing results to the early warning module output.

[0012] Furthermore, the torque detection module is arranged on each input shaft and output shaft of the yaw transmission system, and the temperature detection module is placed on the drive motor; the torque measurement module uses a resistance strain gauge composed of a bridge circuit to measure the torque signal; the temperature measurement module uses a resistance temperature detector, and the temperature sampling points are symmetrically arranged on two sides of the drive motor.

[0013] Furthermore, after the torque detection module and the temperature detection module are installed, the wind turbine is operated normally for a period of time to collect historical data and establish a historical database, which at least includes the input shaft torque, output shaft torque, motor temperature, and ambient temperature of the yaw transmission system.

[0014] Furthermore, the fault judgment model in the system control module is specifically as follows: judging the consistency between the torque direction of each input shaft and the direction of the output shaft, if the directions are inconsistent, it indicates that the current wind turbine yaw transmission system has a fault, if the directions are consistent, proceeding to the next step of judgment; after the direction judgment condition is met, comparing whether the performance index value meets the first threshold requirement, by comparing whether the performance index value meets the first threshold requirement, if it is satisfied, it indicates that the current wind turbine yaw transmission system is operating normally; if the first threshold requirement is not met, further verifying whether the performance index value meets the second threshold requirement, if not, it indicates that the current wind turbine yaw transmission system has a fault and needs to be shut down for maintenance; if the performance index value meets the second threshold requirement, it indicates that there is a hidden danger in the wind turbine yaw transmission system.

[0015] Furthermore, the mean and standard deviation of the difference between the input torque and the output torque of the yaw transmission system, the mean and standard deviation of the difference between the maximum input torque and the minimum input torque, and the mean and standard deviation of the difference between the motor temperature and the ambient temperature are calculated, and a mathematical statistical model is selected for fitting based on the mean and standard deviation of each group of performance index values; the first threshold is selected based on the 90% confidence interval of the statistical model, and the second threshold is selected based on the 95% confidence interval of the statistical model.

[0016] Furthermore, it is detected that the sum of the torques of the input shafts of the yaw transmission system and the torque of the output main shaft satisfy the following relationship:

[0017]

[0018] M1=M2=…=M n

[0019] Where M i is the torque of the input shaft, M o is the torque of the output spindle, where M i With M o The direction should be consistent;

[0020] The operating status of the wind turbine yaw drive system is determined by the following relationship:

[0021] M i *M o >0

[0022]

[0023] 0≤|M i max -M i min |≤ε 21 ≤ε 22

[0024] 0≤|T i max -T i min |≤ε 31 ≤ε 32

[0025] T i ≤T max

[0026] Where M i is the torque of the input shaft, M o is the torque of the output shaft, ε 11 , ε 21 , ε 31 is the first threshold of the corresponding indicator, ε 12 , ε 22 , ε 32 is the second threshold of the corresponding indicator, T i is the motor operating temperature, Tmax is the full load operating temperature, M imax Maximum input torque, M imin Minimum input torque.

[0027] And, a fault detection method for the operating condition of a yaw transmission system of a wind turbine:

[0028] A fault judgment model is established by selecting multiple indicators of the yaw transmission system of the wind turbine, including the difference between the total input torque and the output torque, the difference between the maximum input torque and the minimum input torque, and the difference between the temperature of each drive motor and the ambient temperature;

[0029] A mathematical statistical model of each index is established based on the historical data of the yaw system of the wind turbine; the historical data is the data recorded during the normal operation of the wind turbine, including the torque of each input shaft and the torque of the output shaft of the yaw transmission system, the temperature of each drive motor and the ambient temperature;

[0030] Establish various parameters in the fault judgment model based on mathematical statistical models;

[0031] Real-time collection of torque and temperature at the corresponding detection position of the wind turbine yaw transmission system to obtain various indicators;

[0032] Each index is input into the fault judgment model to judge the working status of the yaw transmission system of the wind turbine.

[0033] Furthermore, the fault judgment model is specifically as follows: judging the consistency between the torque direction of each input shaft and the direction of the output shaft, if the directions are inconsistent, it indicates that the current wind turbine yaw transmission system has a fault, if the directions are consistent, proceeding to the next step of judgment; after the direction judgment condition is met, comparing whether the performance index value meets the first threshold requirement, by comparing whether the performance index value meets the first threshold requirement, if it is satisfied, it indicates that the current wind turbine yaw transmission system is operating normally; if the first threshold requirement is not met, further verifying whether the performance index value meets the second threshold requirement, if not, it indicates that the current wind turbine yaw transmission system has a fault and needs to be shut down for maintenance; if the performance index value meets the second threshold requirement, it indicates that there is a hidden danger in the wind turbine yaw transmission system.

[0034] Furthermore, the mean and standard deviation of the difference between the input torque and the output torque of the yaw transmission system, the mean and standard deviation of the difference between the maximum input torque and the minimum input torque, and the mean and standard deviation of the difference between the motor temperature and the ambient temperature are calculated, and a mathematical statistical model is selected for fitting based on the mean and standard deviation of each group of performance index values; the first threshold is selected based on the 90% confidence interval of the statistical model, and the second threshold is selected based on the 95% confidence interval of the statistical model.

[0035] Furthermore, it is detected that the sum of the torques of the input shafts of the yaw transmission system and the torque of the output main shaft satisfy the following relationship:

[0036]

[0037] M1=M2=…=M n

[0038] Where M i is the torque of the input shaft, M o is the torque of the output spindle, where M i With M o The direction should be consistent;

[0039] The operating status of the wind turbine yaw drive system is determined by the following relationship:

[0040] M i *M o >0

[0041]

[0042] 0≤|M imax -M imin |≤ε 21 ≤ε 22

[0043] 0≤|T imax -T i min |≤ε 31 ≤ε 32

[0044] T i ≤T max

[0045] Where M i is the torque of the input shaft, M o is the torque of the output shaft, ε 11 , ε 21 , ε 31 is the first threshold of the corresponding indicator, ε 12 , ε 22 , ε 32 is the second threshold of the corresponding indicator, T i is the motor operating temperature, T max is the full load operating temperature, M imax Maximum input torque, M imin Minimum input torque.

[0046] Compared with the prior art, the present invention and its preferred embodiments have the following beneficial effects:

[0047] (1) The torque and temperature detection technology is applied to the yaw fault detection system to establish an effective condition monitoring and fault diagnosis mechanism, help the unit improve safety, stability and economy, timely understand the operation status of the internal components of the unit, make correct diagnosis of different fault types, and achieve the purpose of early prevention and timely troubleshooting.

[0048] (2) Compared with the existing wind turbine yaw transmission system, the working status of the yaw transmission system can be known without disassembling the main components of the transmission system, eliminating the need to shut down the machine to disassemble the components for maintenance, saving manpower and material resources.

[0049] (3) The design concept of this scheme can not only be applied to the yaw transmission system of the wind turbine, but can also be promoted and used in various transmission systems, such as: machine tool spindle feed system, vehicle gearbox, etc.

[0050] (4) A real-time measurement method for indirectly monitoring the working status of the transmission system is proposed. This method can obtain the working status of the transmission system without stopping the system or disassembling parts. It can also respond in real time through the early warning module, making it easy for maintenance personnel to grasp the current working status of the system in a timely manner, greatly improving the detection efficiency. The detection process does not interfere with the normal operation of the equipment, avoids downtime, and ensures the operation of the fan. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0052] Figure 1 is a flow chart of a method according to an embodiment of the present invention;

[0053] Figure 2 Schematic diagram of installation positions of modules related to fault detection of a yaw transmission system of a wind turbine according to an embodiment of the present invention;

[0054] Figure 3 Schematic diagram of the structure and installation position of the resistance strain gauge according to an embodiment of the present invention;

[0055] Figure 4 It is a schematic diagram of the composition of a fault detection system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0056] In order to make the features and advantages of the present invention more clearly understood, the following embodiments are specifically described in detail with reference to the accompanying drawings:

[0057] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0058] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0059] The embodiment of the present invention first provides a fault detection system for the operation status of a yaw transmission system of a wind turbine, comprising: a system control module, a torque detection module, a temperature detection module, and an early warning module;

[0060] Among them, the torque detection module is used to detect the torque of the output main shaft and each input shaft of the yaw transmission system;

[0061] The temperature detection module is used to detect the temperature of each drive motor of the yaw transmission system;

[0062] The system control module exchanges information with the torque detection module, the temperature detection module, and the early warning module. The system control module processes the torque and temperature information collected by the torque detection module and the temperature detection module, determines whether there is an abnormal situation, obtains the performance index value, establishes the corresponding mathematical statistical model, establishes the fault data model according to the mathematical statistical model and the performance index value, detects the working status of the yaw transmission system, and transmits the processing results to the early warning module. The early warning module outputs the processing results, such as Figure 4 shown.

[0063] like Figure 2 As shown, in a preferred embodiment, the torque detection module is placed on each input shaft 2 and output shaft 3, and the temperature detection module is placed on the drive motor 1. The measurement circuit is led to the industrial computer, which integrates and compares the information, makes a fault judgment, and outputs the detection results to the early warning module in real time.

[0064] As a preferred embodiment, the torque measurement module uses a resistance strain gauge to measure the torque signal. Its structure and principle are as follows: Figure 3 As shown in the figure, the resistance strain gauge is pasted on the specified position of the measured spindle surface. When the measured spindle is strained by the force, the strain gauge used for testing also undergoes the same mechanical deformation, causing the resistance of the strain gauge to change accordingly. At this time, the resistance strain gauge converts the deformation of the spindle under the torque into the output of the resistance change, and the signal is processed by the conversion circuit to obtain the torque signal.

[0065] For metal strain gauges used to measure strain, it is hoped that the resistance of the strain gauge will only change with strain and will not be affected by other factors. However, in practical applications, the resistance of the strain gauge is greatly affected by the ambient temperature (including the temperature of the measured object), and the resistance change caused by the ambient temperature change is almost of the same order of magnitude as the resistance change caused by the specimen strain, which will cause a large measurement error. Therefore, the torque measurement module adopts a bridge circuit. When the resistance increments of adjacent arms of the bridge are opposite and the resistance increments of the relative arms are the same, the bridge output increases; when the resistance increments of adjacent arms of the bridge are the same and the resistance increments of the relative arms are opposite, the bridge output decreases. This characteristic is the addition and subtraction characteristic of the bridge. Using this characteristic, sensitivity can be improved, temperature compensation can be achieved, and interference factors can be eliminated.

[0066] Preferably, the temperature measurement module uses a resistance temperature detector (RTD). The resistance temperature detector is an electrical device. Unlike the voltage used by thermocouples, it uses another property of the material that changes with temperature - resistance. The resistance devices used can be divided into: RTD and thermistor. RTD is similar to thermistor, and the resistance changes with temperature. As long as the resistance change of the temperature-sensitive thermal resistor is measured, the temperature can be measured. The difference is that thermistors are made of semiconductor materials, while RTDs are made of metals, so they are also called platinum resistors, and some are made of nickel or copper. RTD can take many different shapes, such as winding, film, etc. RTD is the most accurate and stable temperature sensor, and its linearity is better than that of thermocouples and thermistors. In this embodiment, the temperature sampling points are symmetrically arranged on the left and right sides of the drive motor.

[0067] After the torque detection module and the temperature detection module are installed, the wind turbine operates normally for a period of time to collect historical data and establish a historical database, including input shaft torque, output shaft torque, motor temperature, ambient temperature, etc.

[0068] Based on the above system, the present invention adopts a fault detection method for the operation status of the yaw transmission system of a wind turbine, such as Figure 1 As shown, the following steps are included:

[0069] Step 1: Select multiple indicators to establish a fault judgment model;

[0070] Step 2: Establish mathematical statistical models of various indicators based on historical data of wind turbine yaw system;

[0071] Step 3: Establish the parameters in the fault judgment model based on the mathematical statistical model;

[0072] Step 4: The torque detection module and the temperature detection module collect the torque and temperature of the corresponding detection position of the yaw transmission system of the wind turbine in real time to obtain various indicators;

[0073] Step 5: Input each index into the fault judgment model to judge the working status of the yaw transmission system of the wind turbine.

[0074] The historical data is the data recorded during the normal operation of the wind turbine, including the torque of each input shaft and each output shaft of the yaw transmission system, the temperature of each drive motor and the ambient temperature.

[0075] According to the historical database, the data of various indicators can be obtained, including the difference between the sum of input torque and output torque; the difference between the maximum input torque and the minimum input torque; and the difference between the motor temperature and the ambient temperature. The mean and standard deviation of each group of performance indicator values ​​are calculated. According to the central limit theorem, when the sample is large enough, the performance indicator value should obey the normal distribution. The corresponding normal distribution model is established, and the model parameter inversion and parameter test are performed to obtain the mathematical statistical model of the corresponding indicator value.

[0076] In this embodiment, the sum of the torques of the input shafts and the torque of the output main shaft should satisfy the following relationship:

[0077]

[0078] M1=M2=…=M n

[0079] Where M i is the torque of the input shaft, M o is the torque of the output spindle, where M i With M o The direction should remain consistent.

[0080] In this embodiment, the temperature of each drive motor of the yaw system should be kept consistent and lower than the allowable temperature of the motor, that is:

[0081] T1=T2=…=T n

[0082] T i ≤T max

[0083] Where, T i is the motor operating temperature, T max is the allowable temperature of the motor.

[0084] In this embodiment, the operating status of the yaw transmission system of the wind turbine is determined by the following relationship:

[0085] M i *M o >0

[0086]

[0087] 0≤|Mi max -M i min |≤ε 21 ≤ε 22

[0088] 0≤|T i min -T i min |≤ε 31 ≤ε 32

[0089] T i ≤T max

[0090] Where M i is the torque of the input shaft, M o is the torque of the output shaft, ε 11 , ε 21 , ε 31 is the first threshold of the corresponding indicator, ε 12 , ε 22 , ε 32 is the second threshold of the corresponding indicator, T i is the motor operating temperature, T max is the full load operating temperature, M i max Maximum input torque, M i min Minimum input torque.

[0091] The first threshold for determining the relationship is selected based on the 90% confidence interval of the statistical model, and the second threshold is selected based on the 95% confidence interval of the statistical model.

[0092] The specific fault judgment process is as follows: judge the consistency between the torque direction of each input shaft and the direction of the output shaft. If the directions are inconsistent, it means that the current wind turbine yaw transmission system has a fault. If the directions are consistent, proceed to the next step of judgment; after the direction judgment conditions are met, compare whether the performance index value meets the first threshold requirement. By comparing whether the performance index value meets the first threshold requirement, if it is satisfied, it means that the current wind turbine yaw transmission system is operating normally; if the first threshold requirement is not met, further verify whether the performance index value meets the second threshold requirement. If it is not satisfied, it means that the current wind turbine yaw transmission system has a fault and needs to be shut down for maintenance; if the performance index value meets the second threshold requirement, it means that there is a hidden danger in the yaw transmission system of the wind turbine, and it is necessary to choose an appropriate time to check.

[0093] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other forms of fault detection systems and methods for the operating conditions of the yaw transmission system of a wind turbine under the inspiration of the present invention. All equivalent changes and modifications made within the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims

1. A fault detection system for the operation status of a yaw transmission system of a wind turbine, characterized in that: include: System control module, torque detection module, temperature detection module and early warning module; The torque detection module is used to detect the torque magnitude and direction of the output main shaft and each input shaft of the yaw transmission system; The temperature detection module is used to detect the temperature of each drive motor of the yaw transmission system and the ambient temperature in the wind turbine cabin; The system control module exchanges information with the torque detection module, the temperature detection module, and the early warning module to process the torque and temperature information collected by the torque detection module and the temperature detection module, determine whether there is an abnormal situation, and obtain performance index values; detect the working status of the yaw transmission system according to the fault data model, and transmit the processing results to the early warning module output.

2. A fault detection system for the operation status of a yaw transmission system of a wind turbine according to claim 1, characterized in that: The torque detection module is arranged on each input shaft and output shaft of the yaw transmission system, and the temperature detection module is placed on the drive motor; the torque measurement module uses a resistance strain gauge composed of a bridge circuit to measure the torque signal; the temperature measurement module uses a resistance temperature detector, and the temperature sampling points are symmetrically arranged on the two sides of the drive motor.

3. A fault detection system for the operation status of a yaw transmission system of a wind turbine according to claim 1, characterized in that: After the torque detection module and the temperature detection module are installed, the wind turbine is operated normally for a period of time to collect historical data and establish a historical database, which at least includes the input shaft torque, output shaft torque, motor temperature, and ambient temperature of the yaw transmission system.

4. A fault detection system for the operation status of a yaw transmission system of a wind turbine according to claim 1, characterized in that: The fault judgment model in the system control module is specifically as follows: judging the consistency between the torque direction of each input shaft and the direction of the output shaft, if the directions are inconsistent, it indicates that the current wind turbine yaw transmission system has a fault, if the directions are consistent, proceeding to the next step of judgment; after the direction judgment condition is met, comparing whether the performance index value meets the first threshold requirement, by comparing whether the performance index value meets the first threshold requirement, if it is satisfied, it indicates that the current wind turbine yaw transmission system is operating normally; if the first threshold requirement is not met, further verifying whether the performance index value meets the second threshold requirement, if not, it indicates that the current wind turbine yaw transmission system has a fault and needs to be shut down for maintenance; if the performance index value meets the second threshold requirement, it indicates that there is a hidden danger in the wind turbine yaw transmission system.

5. A fault detection system for the operation status of a yaw transmission system of a wind turbine according to claim 4, characterized in that: The mean and standard deviation of the difference between the input torque and the output torque of the yaw transmission system, the mean and standard deviation of the difference between the maximum input torque and the minimum input torque, and the mean and standard deviation of the difference between the motor temperature and the ambient temperature are calculated, and a mathematical statistical model is selected for fitting according to the mean and standard deviation of each group of performance index values; the first threshold is selected according to the 90% confidence interval of the statistical model, and the second threshold is selected according to the 95% confidence interval of the statistical model.

6. A fault detection system for the operation status of a yaw transmission system of a wind turbine according to claim 4, characterized in that: The sum of the torques of the input shafts of the yaw transmission system and the torque of the output main shaft satisfy the following relationship: M1=M2=…=M n Where M i is the torque of the input shaft, M o is the torque of the output spindle, where M i With M o The direction should be consistent; The operating status of the wind turbine yaw drive system is determined by the following relationship: M i *M o >0 0≤|M i max -M i min |≤ε 21 ≤ε 22 0≤|T i max -T i min |≤ε 31 ≤ε 32 T i ≤T max Where M i is the torque of the input shaft, M o is the torque of the output shaft, ε 11 , ε 21 , ε 31 is the first threshold of the corresponding indicator, ε 12 , ε 22 , ε 32 is the second threshold of the corresponding indicator, T i is the motor operating temperature, T max is the full load operating temperature, M imax Maximum input torque, M imin Minimum input torque.

7. A method for detecting the operating condition of a yaw transmission system of a wind turbine, characterized in that: A fault judgment model is established by selecting multiple indicators of the wind turbine yaw transmission system, including the difference between the total input torque and the output torque, the difference between the maximum input torque and the minimum input torque, and the difference between the temperature of each drive motor and the ambient temperature; A mathematical statistical model of each index is established based on the historical data of the yaw system of the wind turbine; the historical data is the data recorded during the normal operation of the wind turbine, including the torque of each input shaft and the torque of the output shaft of the yaw transmission system, the temperature of each drive motor and the ambient temperature; Establish various parameters in the fault judgment model based on mathematical statistical models; Real-time collection of torque and temperature at the corresponding detection position of the wind turbine yaw transmission system to obtain various indicators; Each index is input into the fault judgment model to judge the working status of the yaw transmission system of the wind turbine.

8. A method for detecting the operating condition of a yaw transmission system of a wind turbine according to claim 7, characterized in that: The fault judgment model is specifically as follows: judging the consistency between the torque direction of each input shaft and the direction of the output shaft, if the directions are inconsistent, it indicates that the current wind turbine yaw transmission system has a fault, if the directions are consistent, proceeding to the next step of judgment; after the direction judgment condition is met, comparing whether the performance index value meets the first threshold requirement, by comparing whether the performance index value meets the first threshold requirement, if it is satisfied, it indicates that the current wind turbine yaw transmission system is operating normally; if the first threshold requirement is not met, further verifying whether the performance index value meets the second threshold requirement, if not, it indicates that the current wind turbine yaw transmission system has a fault and needs to be shut down for maintenance; if the performance index value meets the second threshold requirement, it indicates that there is a hidden danger in the wind turbine yaw transmission system.

9. A method for detecting the operating condition of a yaw transmission system of a wind turbine according to claim 8, characterized in that: The mean and standard deviation of the difference between the input torque and the output torque of the yaw transmission system, the mean and standard deviation of the difference between the maximum input torque and the minimum input torque, and the mean and standard deviation of the difference between the motor temperature and the ambient temperature are calculated, and a mathematical statistical model is selected for fitting according to the mean and standard deviation of each group of performance index values; the first threshold is selected according to the 90% confidence interval of the statistical model, and the second threshold is selected according to the 95% confidence interval of the statistical model.

10. A method for detecting the operating condition of a yaw transmission system of a wind turbine according to claim 8, characterized in that: The sum of the torques of the input shafts of the yaw transmission system and the torque of the output main shaft satisfy the following relationship: M1=M2=…=M n Where M i is the torque of the input shaft, M o is the torque of the output spindle, where M i With M o The direction should be consistent; The operating status of the wind turbine yaw drive system is determined by the following relationship: M i *M o >0 0≤|M i max -M i min |≤ε 21 ≤ε 22 0≤|T i max -T i min |≤ε 31 ≤ε 32 T i ≤T max Where M i is the torque of the input shaft, M o is the torque of the output shaft, ε 11 , ε 21 , ε 31 is the first threshold of the corresponding indicator, ε 12 , ε 22 , ε 32 is the second threshold of the corresponding indicator, T i is the motor operating temperature, T max is the full load operating temperature, M imax Maximum input torque, M imin Minimum input torque.

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