基于泄漏电流三次谐波分析的高压设备在线监测方法

Online monitoring method of high voltage device based on leakage current third-harmonic analysis

避雷器在保证高压电网的安全可靠运行方面具有重要作用,目前许多避雷器在线监测和诊断方法都是通过将泄露电流分解为容性和阻性来实现,其中避雷器泄漏电流的阻性分量尤其是阻性分量中的三次谐波分量,与避雷器氧化锌阀片的降解程度直接相关。文中提出了一种能够在干燥和污染情况下对避雷器进行在线监测的方法,针对三种不同类型的绝缘子检测了它们的总泄露电流以及内部、外部泄露电流。这种方法主要是对实测电流信号的幅值、频率、相位角特征进行提取和分析,分析方法则使用Prony分析以及希尔伯特变换,使用MTLAB软件平台编程。测试结果显示该方法在避雷器在线监测中具有一定可行性。除此以外,文中基于PSCAD对避雷器进行了建模仿真,研究电压谐波对泄漏电流测量的影响。

Surge arresters(SAs)play a key role in protecting the safe and stable operation of high voltage power grid.Various diagnostic online monitoring methods of surge arrester are based on the decomposition of the measured leakage current into their capacitive and resistive components.The resistive component of the leakage current of surge arrester,in particular,the third harmonic component,is known as to be directly related to the degree of degradation of the ZnO blocks.This paper proposes an online monitoring method for the surge arrester under dry and pollution conditions when measuring either the total leakage current or both the internal and external leakage currents of three different types of surge arresters.The proposed technique of extracting the magnitudes and harmonic content of the measured voltage and current signals based on Prony analysis-Hilbert transform approach has proved its viability in handling both stationary and non-stationary signals with small number of samples.The test results show that the proposed method is feasible in the on-line monitoring of arresters.In addition,a modeling simulation is conducted based on PSCAD,and the effect of voltage harmonics on the leakage current measurement is studied as well.