长串绝缘子高海拔人工污秽试验泄漏电流分析

Leakage Current Analysis of Long String Insulators Under High-altitude Artificial Pollution Tests

为获得长串绝缘子泄漏电流随盐密及海拔的变化规律,开展了不同海拔高度、不同盐密类型下的绝缘子人工污秽试验,获得了泄漏电流波形数据,通过傅里叶变换将泄漏电流从时域变换到频域。对泄漏电流幅频和相位特性的分析结果表明随着泄漏电流幅值的增大,3次谐波的含量逐渐减少,电流波形越接近正弦波,电流电压相位差也逐渐减小,在泄漏电流幅值为54.23、101.50、355.28 m A时,3次谐波含量分别为47%、38.6%、20.6%,电流电压相位差分别为–18.04°、–17.17°、–13.68°。对不同盐密的绝缘子串的泄漏电流峰值进行分析发现,可用泄漏电流峰值表征绝缘子污秽度。通过对不同海拔下泄漏电流峰值分析发现,泄漏电流峰值与海拔高度满足一定的关系式。研究结果表明不同海拔地区的绝缘子的防污闪预警泄漏电流阈值应进行差异化设定,该研究规律对高海拔地区绝缘子安全稳定运行具有一定的指导意义。

In order to obtain a law that the leakage current of long string insulators changes with salt deposit density（SDD） and altitude, we carried out the artificial contamination tests at different altitudes and different SDDs, and obtained the waveform data of leakage current. Then we changed the leakage current from the time domain to the frequency domain through Fourier transform. The analysis results of the leakage current amplitude-frequency and phase characteristics show that, with the increase of leakage current amplitude, the content of third harmonic decreases, the current waveform more approaches sine wave, and current and voltage phase difference is gradually reduced. When the leakage current amplitude is 54.23 mA, 101.50 mA, and 355.28 mA, the third harmonic content is 47%, 38.6%, and 20.6%, the current and voltage phase difference is -18.04°, -17.17°, and-13.68°, respectively. Through analyzing the insulator strings＇ leakage current peak in different SDDs, it can be found that insulators＇ contamination degree can be characterized by leakage current peak. Through analyzing the leakage current peak at different altitudes, it can be found that leakage current peak and altitude satisfy a certain formuila. The results show that the insulator contamination flashover leakage current warning threshold should differentiate at different altitudes, the rule has a certain significance for safe and stable operation of insulators in high altitude areas.