Research On Insulation State Detection Method Of Wind Power Generator

The safty,stability,and reliability ooperation of a wind turbine is related to the stability of power grid and power quality.Because the wind turbine is usually in the harsh outdoor environment,the insulation material inside the generator is easy to deteriorate under the action of long-term extreme temperature,salt corrosion,and mechanical stress,resulting in partial discharge.If not detected early,when the partial discharge continues If it develops,it will eventually lead to internal insulation breakdown and even short circuit accidents.Therefore,it is very important for the stable and reliable operation of wind turbine to detect the early partial discharge inside the generator and carry out maintenance in a planned way.According to the maintenance characteristics of wind turbine,aiming at the shortcomings of single detection method,too large volume,inconvenient to carry and unable to judge from multiple angles,a set of multi-functional insulation state detector for wind turbine is developed,which integrates ultrasonic wave detection method,UHF detection method,high-frequency current detection method and infrared thermal imaging method The insulation state of wind turbine running on site can be detected quickly from multiple angles.Therefore,this paper studies the following aspects:(1)Firstly,several typical characteristics of wind turbine internal insulation fault are studied,and the generation mechanism,development process and harm of each fault are analyzed.Aiming at these fault characteristics,several detection methods are studied: ultrasonic method,UHF method,high frequency current method and infrared thermal imaging method.The principle,system installation structure and advantages of these detection methods are analyzed and shortcomings.(2)Then,a portable instrument for wind turbine insulation state detection is developed,which integrates ultrasonic detection,UHF detection,high frequency current detection and infrared thermal imaging,including hardware design and software system design.The design of hardware circuit includes sensor selection,a signal amplification circuit,a filter circuit,data acquisition circuit,communication circuit and the installation and detection method of the whole system.The software system design introduces the development platform and various functional modules of the system.(3)Finally,in order to verify the reliability and effectiveness of the project,the accuracy of the detection system of the designed equipment is verified by simulating the insulation defects and actual heating of the wind turbine based on the experimental system of doubly-fed wind power generation.The test results show that:the ultrasonic detection method has obvious directionality,and the intensity of the detected signal is closely related to the angle between the sensor and the discharge point;the UHF signal generated during partial discharge has strong radiation intensity,so the detection sensitivity of the UHF detection system is also very high.This method is suitable for rapid inspection,and the generator can be inspected quickly After the detection signal,ultrasonic detection method can be used to specific positioning detection and exclusion;high frequency current detection system has high sensitivity,can accurately detect the discharge signal of neutral point and outlet bus,and can filter out noise interference;infrared thermal imaging detection can clearly display the thermal distribution state of the starting motor,and can display the overall maximum temperature of the generator The minimum temperature and average temperature can quickly find local hot spots,which is convenient for on-site inspection.