Research And Application Of Partial Discharge Detection Of Switchgear Based On Transient Ground Voltage And Ultrasonic

With the rapid development of China's economy,the power system has entered a stage of rapid development,and high-voltage switchgear is an important electrical equipment in the system.After the switchgear works for a long time,it will generate heat,low efficiency,and reduced insulation strength,which will cause the number of faults in the switchgear to increase year by year and the reliability and instability of the power supply system.80% are caused by the deterioration of insulation characteristics caused by partial discharge.In view of this,the rapid and accurate detection of insulation defects caused by partial discharges in switch cabinets has become an issue of increasing concern to the power industry,and is also one of the hot topics discussed by related research units and personnel.Partial discharge is caused by early high and medium voltage insulation failures.If it is not controlled,this partial discharge phenomenon will gradually destroy the insulation medium in the high voltage switch cabinet and eventually lead to insulation damage.This article first introduces two methods that can effectively detect partial discharge in switchgear-transient earth voltage(TEV)detection method and ultrasonic detection method.Explained the theoretical basis of these two detection methods in detail,and then explained the principle and process of these two detection methods.Aiming at the insufficient sensitivity of the TEV detection method,the acquisition process was improved,and a test platform was built for comparative analysis.The results showed that the sensitivity of the TEV detection method was effectively improved after the amplification detection circuit was added.After comparing the advantages,disadvantages and limitations of a single detection method,in order to reflect the sensitivity and effectiveness of the combined detection of the two methods,four switchgear partial discharge models of the switchgear were designed for comprehensive test comparison,and then the two methods were combined.The detection can effectively detect the partial discharge of the switchgear.TEV and ultrasonic methods refer to and confirm each other,which can effectively determine the type of abnormal signal,improve the accuracy of partial discharge point positioning,and lay the foundation for actual field applications.In order to solve the problems of poor economy of the existing switchgear partial discharge online detection equipment and the insufficient portability of the live detection equipment,this paper developed a set of switchgear partial discharge online detection system suitable for operation in a variety of environments to improve the on-site switchgear On-line detection level of partial discharge.Finally,this article is based on the related research of transient ground voltage and ultrasonic detection method,combined with the application of the new switchgear partial discharge signal online monitoring system developed in this article in field examples,to verify the joint detection of TEV and ultrasonic method.Through the horizontal and vertical comparison,combined with the results of the transient ground voltage and the ultrasonic detection method applied in the field,the defect can be well located and distinguished.