基于泄漏电流基波阻性分量的绝缘子污秽度表示方法的研究

绝缘子污秽状态判断对电网安全工作意义重大。基于污秽绝缘子串等效电路的理论分析,建立了绝缘子串泄漏电流试验回路,对洁净及不同污秽情况下的绝缘子串泄漏电流进行了测量,并利用FFT变换分析绝缘子泄漏电流频谱,提取了泄漏电流基波阻性分量,研究了泄漏电流基波阻性分量同污秽度及相对湿度间的关系。结果表明,污秽干燥情况下,绝缘子泄漏电流较小且主要为容性电流;与洁净时相比,绝缘子串染污时总的泄漏电流及其基波分量的变化并不明显,而泄漏电流基波阻性分量同污秽盐密及相对湿度呈非线性关系,低湿度情况下变化更显著,可以通过泄漏电流基波阻性分量来表示绝缘子的污秽程度,这比利用总泄漏电流进行判断更有效;高湿度情况下泄漏电流基波阻性分量法已不适合判断绝缘子污秽度。且该方法无需对绝缘子串安装集流环,保证了系统安全性。

Representation Method of Insulator Pollution Degree Based on Leakage Current Fundamental Resistive Component

Based on the theoretical analysis of insulator strings’ equivalent circuit,this paper establishes a leakage current test circuit of insulator strings.The leakage currents of insulator strings in clean and pollution conditions are measured.The leakage current spectrum is analyzed by using FFT,and the leakage current fundamental resistive component is extracted.The relations among the leakage current fundamental resistive component,pollution degree and relative humidity are obtained.The results show that the leakage current is small and mainly contains capacitive current in dry pollution.Compared with the clean condition,the changes of leakage current and leakage current fundamental component of the polluted insulator are not obvious,however the leakage current fundamental resistive component has non-linear relations with the pollution’s ESDD and the relative humidity.The change of leakage current fundamental resistive component is more obvious in low humidity condition,therefore the pollution degree of insulator can be more effectively represented by measuring the leakage current fundamental resistive component instead of the leakage current.However,this method is not suitable for estimating the pollution degree in high humidity condition.Furthermore,the collector ring need not be fixed on the insulator strings,which ensures the system security.