Measurement Of Metal Oxide Arrester Resistive Current And Implementation

As an important over-voltage protection device, Metal Oxide Arrester (MOA) iswidely used in modern power system. MOA mostly works in the outdoors, so itsinternal will be easily aging or damp, which will affect the work of MOA and morelikely cause accidents. So the regular detection is necessary to ensure its properfunctioning.Now most detection methods to inspect the performance of MOA are through theanalysis of the resistive current in its leakage current. But it is difficult to detect theresistive current, because the result of detection can be easily affected by other signalsin grid. Therefore, we need to design a MOA testing equipment which can simply beused to accurately detect the performance of MOA.On the basic of comparing the existent detection methods, this paper designs anoff-line MOA testing equipment according to the requirement of a venture. Thisequipment is controlled by a digital signal controller (DSC)-dsPIC30F6015, which cananalyze the leakage current by harmonic analysis to make a judgment. Except forcollecting data, this equipment can analyze, display, print and save the data. What’smore, the accuracy of testing result is improved.However, the distance between the site of collecting voltage data and the site ofcollecting leakage current is a little far in fact, sometimes it can be hundreds meters.Because of this, the off-line MOA testing equipment cannot be used to monitor theperformance of MOA in its work site. Then in this paper，a set of online monitoringsystem is designed by the technology of wireless communication. In the system, voltageand leakage current signals can be separately but synchronically collected, using themethod of synchronizing with the clock of GPS module. Then the collected data aretransferred to PC by wireless transfer module, and the designed software on computercan analyze, print and save these data. Compared to off-line testing equipment, thissystem is superior, because it can monitor the performance of MOA at real-time and it is safer to be used in MOA work site.In order to debug and verify the MOA testing equipment, this paper also designs astandard AC single-phase signal generator. The exam results show that voltage andleakage current data are accurately detected, and the accuracy can satisfy therequirement of the venture. Besides, the on-line monitoring system can work stably andreliably, so operators will able to monitor the performance of MOA far away from thetest site.