Research On Contactless On-line Monitoring Of Over-voltage In Powergrid

The operation experience and research shows that overvoltage is the main factor which caused grid insulation damage in the power system, but also the main reference option of electrical equipment in insulation conditions selection. Studying various overvoltage causes, duration and amplitude size etc, and taking measures to limit these characteristics, is the premise of the electric power system choosing insulation coordination, and it has great significance to guarantee the safe operation of electric power system and the continuous electrical equipment manufacturing.In addition to the theoretical analysis of overvoltage, we also need to monitor and analyse various overvoltage occurred in actual power system operation. At present our country mainly rely PT or CT on overhead busbar voltage monitoring, this paper puts forward a new kind of contact-less voltage measuring device. According to maxwell electrostatic equation, we can get the relationship between voltage and charge of n long straight wires parellel with, to deduct the equations about the relationship of busbar voltage and measure-line voltage. Compared with the traditional PT,CT, this contact-less device has advantages with small size, low cost, safety, stable operation, no ferromagnetic parts etc.This article built various overvoltage circuit models by the ATP-EMTP, and by simulation waveform we can see the overvoltage features consistent with calculation.