Development Of Zinc Oxide Arrester On-Line Monitoring System

Zinc oxide arrester has become the main power system over-voltage protection device in recent years. Its application is more and more widely. The thermal damage,transient and syntonic over-voltage, inner moistened of Zinc oxide arrester and so on,will lead to arrester's damage even exploding. To protect the security of power system, it is necessary to monitor arrester on-line, so we can find out the hidden trouble and the anomalies of arrester in time.In recent years, status online monitoring of power equipment has become a hot topic. In emerge in endlessly on-line monitoring methods, the method that extracting its resistive component of leakage current from earth is relatively mature and precise.The method that regarding the phase B voltage zero point as the starting point to deduce a new method of impedance leakage current extraction, has been verified by the simulation which can effectively eliminate the power grid harmonic voltage and interphase interference coupling capacitance and accurately extract the resistance leakage current, timely and accurate diagnose the work condition of Zinc Oxide arrester.In this paper, a Zinc Oxide arrester on-line monitoring software and hardware system has been designed and manufactured. The system includes signal acquisition and data processing section. First, DSP TMS320F2812 is the core of the whole system hardware circuit, including signal sampling, filtering,and conditioning circuit,D/A conversion circuit, DSP minimum system, data storage, etc. On this basis the software programs have been designed, like the A/D sampling subprogram, filter algorithm subprogram, integral algorithm subprogram, FFT algorithm subprogram,resistance current extraction subprogram, etc. The programs have been tested by using the method of software programming and the method of signal generator producing testing wave. Low frequency interference has been found in the process of testing. A new type of digital integral used to solve the effects of the interference tothe integral link aimed at this phenomenon is proposed in this paper. Finally, zinc oxide varistor has been used in practical circuit instead of zinc oxide arrester. Then practical circuit experiment under low voltage grade has been done: data have been acquired and processed to extract the resistance leakage current. The results have been compared and analyzed in the last part. The results prove that this system is reasonable and effective.