基于SWT的GIS电压互感器二次侧干扰分析

PT secondary interference of GIS based on synchronous compression wavelet transform

特快速暂态过电压(VFTO)是气体绝缘变电站(GIS)中切换隔离开关时产生的特殊电磁暂态现象。VFTO会以传导和辐射方式影响二次设备的正常运行。为探究VFTO对二次设备的干扰特性,文中采用自制的二次侧干扰测量装置对某1000 kV GIS的电压互感器(PT)二次侧共模干扰进行现场实测。接着,对比了5种时频分析方法的性能,采用其中性能较优的同步压缩小波变换(SWT)对实测波形进行了时频分析。实测结果表明:PT二次侧的共模干扰电压峰峰值最高可达9.65 kV。微脉冲的时频分析结果表明:7.8 MHz频率分量幅值高,且贯穿波形的始终,是PT二次侧干扰的主导频率分量。该分析结果可为GIS中二次设备的电磁抗扰度测试和电磁防护设计提供参考。

Very fast transient overvoltage(VFTO)is a special electromagnetic transient phenomenon when the isolation switch is switched in a gas insulated substation(GIS).VFTO affects the normal behavior of secondary equipments through conduction and radiation.In order to explore the interference characteristics of VFTO on secondary equipments,a self-made interference measuring device is used in this paper to conduct field measurement of the common mode interference on the secondary side of the potential transformer(PT)in 1000 kV GIS.Secondly,the performances of five time-frequency analysis methods are compared,and the time-frequency analysis of the measured waveforms is carried out using the synchronous compression wavelet transform with the better performance.The measured results in this paper show that the peak-to-peak voltage of common-mode interference voltage on the secondary side of PT reaches up to 9.65 kV.The time-frequency analysis results show that the 7.8 MHz frequency component has the highest amplitude,so it is the dominant frequency component of PT secondary side interference throughout the waveform.The results in this paper provide references for the electromagnetic immunity test and electromagnetic protection design of secondary equipment in GIS.