Reseach On The Partial Discharge Detection And Diagnise Method In HV Swithgear Based On TEV And Ultrasonic Wave

High-voltage switchgear is an important electrical equipment in the power system,its safe and reliable operation ensure the safety and stability of the grid.Partial discharge is the main cause of HV switchgear insulation failure,but also an important sign of insulation deterioration.It is important to detect the local discharge of the switchgear quickly and accurately for timely removal of equipment defects and improvement of power supply reliability.In this paper,the ultrasonic detection method of HV switchgear and the method of PD detection of transient earth voltage(TEV)are studied.According to the characteristics of the PD of the switchgear,the development of the corresponding ultrasonic sensors and TEV sensors.Four typical PD defect models were designed and fabricated for needle discharge,creeping discharge,suspension discharge and internal discharge,and the PD test was carried out by pulse current method,AE method and TEV method respectively.At the same time,the feasibility of quantitative analysis of AE and TEV partial discharge detection is studied.The test results show that the discharge type,detection position,signal propagation path and so on will affect the TEV and ultrasonic signal detection amplitude,there is no uniform calibration formula,so the test results of TEV and AE methods can not really reflect the actual apparent discharge,can only be used as a relative value for reference.TEV and AE partial discharge detection calibration methods still need a lot of research.This article establishs the ultrasonic spectrum characteristics library of different kinds of typical discharge model with experiment.BP Neural Network and Support Vector Machine(SVM)were used to identify the pattern of typical partial discharge.The experimental results show that the recognition ability of SVM method is obviously superior in the BP Neural Network,accordingly it is recommended to use SVM algorithm to realize the pattern recognition of ultrasonic partial discharge signal,and its recognition accuracy can reach more than 97%.Finally,based on the above research results,it is proposed to use TEV and ultrasoni c combine method to realize partial discharge detection,and a set of high voltage switchgear integrated partial discharge detection system based on ultrasonic method and TEV method was developed.Based on the time difference between the TEV signal and the ultrasonic array signal,a partial discharge localization method based on the time difference of Arrival(TDOA)is proposed,and the experimental results show that the method has the advantages of simple realization and high positioning precision,which m eets the requirements of engineering application.The development of the high-voltage switchgear integrated partial discharge detection device has the advantages of simple operation,light weight,low cost,portable,single operation and so on,which reduc es the labor intensity of the local discharge cabinet detection.