The Design And Realization Of On Line Monitoring System For Metal Oxide Arrester

With the development of power grid intellectualization,The real-time on-line state monitoring system,as an integral part of building the smart grid,has been widely studied and applied.MOA(Metal Oxide Arrester)is mainly used to protect the power equipment by releasing the over current caused by lighting,breaker operation,short circuit and etc.And its working condition makes a significant sense to the security operation of power system.Thus,design an on-line monitoring system is necessary for MOA's lifecycle information management.This article,first introducing the existing MOA online monitoring methods,and get the external influencing factors through the research and analysis of the existing MOA online monitoring methods.Than,for better planning and design of MOA online monitoring system,through the in-depth analysis on several existing on-line monitoring methods,this paper adopts harmonic analysis method to monitor the leakage current.Furthermore,pointed to the limited times of releasing lightning current for ZnO arrester,an electronic counter been designed to record the operating times for MOA.Thus MOA can be real-time monitored through two function modules—leakage current monitor module and operating times counter module.Experimented with both module confirmed the design can absolutely meet requirements.To simultaneously monitor the leakage current of milliampere and the impulse urrent of hundreds ampere,the paper developed a special lightning sensor,it combined the existing leakage current detecting techniques and MOA act counting technique,can achieve synthetic judgment based on various parameters and effectively detect the real-time status of MOA.Based on AT89C55WD processor,a scheme of on-line monitoring system was given in the paper.The scheme adopted AT89C55WD as center processor,and through RS-485 to communicate,it considered physics characteristics of leakage current and lightning current.What's more,the paper designed hardware circuit,related PCB(Printed Circuit Board)was accomplished and debugging works have been done.On the basis of hardware platform,flow diagrams for each module have been designed,a communication protocol between upper computer and lower computer was also given based on RS485 buses,and some part of the software program based on AT89C55WD was wrote and debugged.Using Visual Studio2013,a MOA monitoring information management system was designed;the field collection date was send to monitoring database through RS485 and formed the statement.In the end,by remote real-time monitoring and analyzing the historical dates,MOA can be effectively monitored.