Research And Design Of Lightning Arrester Intelligent On Line Monitoring System

With the improvement of people’s living standards,people have higher and higher requirements for the safe operation of power system.Zinc oxide arrester(MOA)is an important civil power equipment to ensure the stable and safe operation of China’s power grid.In this paper,a real-time monitoring system for MOA of 500 k V substation is designed.This paper analyzes the working principle and equivalent circuit of MOA,and analyzes the advantages and disadvantages of the commonly used MOA online monitoring methods.The arrester online monitoring system consists of CT monitoring module,PT monitoring module,main control module and upper computer.The CT monitoring module mainly completes the acquisition of leakage current signal,converts it into digital signal,and synchronously uploads it to the main control module.Its hardware mainly includes: high precision zero flux current transformer,controller STM32F407ZGT6,analog-to-digital converter AD7606,wireless communication module Smart Node N616,etc.PT monitoring module mainly completes the acquisition of voltage signal,converts it into digital signal,and synchronously uploads it to the main control module.Its hardware circuit is basically the same as CT monitoring module,only the front-end signal acquisition circuit is different.The main control module mainly receives and processes leakage current and voltage signals,and its hardware mainly includes controller STM32F407ZGT6,wireless communication module Smart Node N616,485 communication interface,etc.The three module structure is used to separate the leakage current and voltage signal effectively,so as to avoid mutual interference between them.The software design of arrester monitoring system consists of CT monitoring module,PT monitoring module,main control module and upper computer software design.The software design of CT monitoring module includes initialization program design,interrupt program design,A/D acquisition and calculation program,clock module program design,temperature and humidity acquisition module program design and synchronous communication module program design.The software design of Pt monitoring module is basically the same as that of CT monitoring module.The software design of the main control module includes the program design of the receiving and sending module of the synchronizer,the program design of the data processing module and the program design of the upper computer communication module.The leakage current and voltage signals are processed by harmonic analysis.The amplitude and phase difference of leakage current and voltage are calculated by fast Fourier transform(FFT).The phase is corrected and the resistive current and capacitive current are calculated.The upper computer realizes data monitoring and historical data query,can monitor real-time data independently,and display leakage current waveform,voltage waveform,leakage current,phase difference,capacitive current and resistive current.Build a test platform,collect a lot of data,through data analysis,the system performance indicators fully meet the design requirements of this topic.