The Research And Design Of The Calibration Instrument Of Arrester Monitor

Zinc oxide arrester and its monitors,which are mainly used for over-voltageprotection of power grid voltage, are widely used in China’s power plants.However,under the effect of power frequency voltage, the zinc oxide arrester becomes aged anddamp, which will affect the normal work. The zinc oxide arrester could monitor theleakage current of arrester on line and judge whether the Zinc oxide arrester’s workingconditions are good or bad. But as time goes by, its accuracy of monitoring willdecline, causing false judgments of the working conditions of the zinc oxide arrester.According to the problems listed above, this paper designed a zinc oxide arrestermonitor calibrator, which mainly checks the full current arrester monitor anddiagnoses the working conditions of Lightning arrester.Firstly, this paper introduced the basic characteristics of zinc oxide surgearresters, analyzed its equivalent circuit in detail, expounded the function,classification of the monitor, elaborated the monitoring methods,and researched ontwo commonly-used verification methods and presented their advantages anddisadvantages.Secondly, this paper proposed two ways of on-line calibration: softwarecompensation method and the improved resistive current harmonic analysis becauseof the defects that the commonly-used calibration method can not achieve onlinecheck. The main application of these two methods is to obtain site MOA wholeleakage of electric current, the resistive electric current and its third harmoniccomponent to determine the quality of the performance of the arrester and its monitor.In this paper, the MOA simulation model was built by the use of matlab simulationsoftware to carry out a detailed analysis and simulation of the two methods.Finally,based on the improved method of the resistive current harmonic analysis,it designed the soft software and hardware. The hardware system includes the circuitdesign of power supply, signal acquisition and conditioning, signal processing andcommunications, human-computer interaction and so on. The software systemincludes the program flow design of data acquisition, data processing and datacommunication module.