Of Moa, Insulation Monitoring Device Design And Signal Processing Issues Discussed

In power system, over voltage does great harm to the installation. In order to protect the installation and ensure that the power work economically and reliably, Metal Zinc Oxide Arrester (MOA) has used in almost all types of installation. With the accretion of the power network capacity and the continuous enhancement of voltage level, the preventive test of arrester is not more and more satisfied with the need of the safety and reliability on power supply. The status maintenance, based on on-line monitoring for insulation, could inspect and monitor the equipments' characters automatically, continuously or timing under without cutting power and breaking away from running system. It can reflect the equipment running status and provide the maintenance standards.Based upon the worse capability of anti-jamming and the low accuracy in MOA on-line monitoring, this paper presents a centralized and decentralized monitoring device for substation by probing particularly the ways of monitoring and theirs qualities. In the device, some measures, about hardware and software, are taken to restrain effectively the disturbance and to improve the accuracy and precision. For hardware, the sensor and wave sampling system are improved. For software, according to the impact of white noise, an algorithm of denoising based on wavelet transform is presented. According to the impact of higher voltage harmonic, an algorithm of harmonic analysis based on anti-alias Fourier transform is discussed. Compared with the traditional way, FFT harmonic analysis, the algorithm increases the monitoring precision and the veracity.Through running insulation on-line monitoring system, the two ways presented in paper, signal denoising algorithm based on wavelet transform as well as harmonic analysis based on anti-alias Fourier transform, are proved to be effective.