Partial discharge detection is an important means to monitor and diagnose the insulation condition of electrical equipment.Detecting the partial discharge condition of equipment,finding and dealing with insulation defects in time can effectively avoid the occurrence of insulation failure.At present,a variety of partial discharge monitoring devices have been developed based on pulse current method,ultra-high frequency method,ultrasonic method and other common methods,but most of them are for single equipment such as GIS,transformer,switchgear and so on.The monitoring cost is high,the utilization rate of the device is low,and the maintenance workload is large,so it is difficult to popularize and apply them.Based on the research of UHF method,a multi-GIS partial discharge monitoring method based on loop time difference method is proposed.At the same time,multi-GIS partial discharge monitoring is carried out.The circuit time difference method is used to determine the discharge equipment quickly and accurately,and the location of the discharge is given.This method uses a set of devices to realize partial discharge monitoring and preliminary positioning in multi-GIS,which greatly reduces the cost of monitoring system and improves the monitoring efficiency.It has important engineering application value.The main research work of this paper is as follows:(1)The propagation characteristics of UHF signal and the location method based on loop time difference are studied.The propagation characteristics of partial discharge signal are analyzed,the topological structure and location method of monitoring system are designed,and relevant algorithms for signal validity judgment,signal start time judgment and feature parameter extraction are proposed.(2)A multi-GIS partial discharge monitoring system based on UHF method is developed.According to the requirement of high sensitivity and wide range monitoring of partial discharge,the hardware structure of stable and reliable monitoring device is designed,and the PC terminal software is developed to realize the functions of on-line monitoring,location,data storage and historical data analysis of partial discharge.(3)The performance of the monitoring system is tested.Selecting partial discharge simulator,various partial discharge models and built-in defects of GIS as partial discharge source,comparing with the mainstream equipment in the market,testing the system performance,then installing the system in the actual GIS equipment,testing the field work ability.The test results show that the monitoring system has strong stability,high sensitivity and accurate positioning.It can realize on-line monitoring and preliminary positioning of partial discharge in multi-GIS. |