The Study Of On-Line Monitoring Systerm For MOA

It is necessary for on-line monitoring system for Metal Oxide Arrester (MOA) to detect its problem and ensure the safe operation of the power system.According to equivalent circuit of MOA, the characteristic of leakage current of MOA and some disturb factors are discussed. The actual methods including the total current method, triphase grounding current methods, capacitance current compensate method, basic resistive wave current method are analyzed. Using basic resistance wave current as a monitoring element and it is realitied by digital waveform analysis. Next, as MOA leakage current is feeble and it exists on high-tension, ferromagnetic condition , a micro-current sensor was designed by theory analysis and experimentation. The structure of current sensor is a circle threading core structure and delicacy signal adjusting and multilayer shield technology are adopted.The hypogyny-machine hardware circuit was designed on the basis of ARM series AT91M40800. According to function of each module, the corresponding software program was designed. The programs, by FFT getting the basic resistance wave current of the amplitude and the phase angle, modifying FFT by window and interpolate arithmetic were provided.In order to promote its anti- interference ability, the system employed a series of methods. At last, in lab, corresponding setup was designed to examine the accuracy and operating reliability of the digital part of the synthetic on-line detecting system for MOA .The experimental studies showed the precision and reliability of the computation and measure.