地线绝缘子间隙放电电流波形特征分析

Analysis on Characteristics of Ground Insulator Gap Discharge Current Waveform

地线绝缘子并联间隙长度的减小,使其在高感应电压影响下极易产生间隙击穿放电,直接威胁电力系统的安全运行。为了解地线绝缘子间隙放电电流波形特征,进行地线绝缘子不同间隙击穿放电试验研究。测量了试验过程中击穿放电电流波形,分析了其时域和频域特征。分析结果表明,放电电流波形起始段会产生一个大脉冲,脉冲电流幅值达到6 A左右;大脉冲电流过后出现正弦电流波形,其电流幅值约为0. 25 A,持续1～2个周波之后,电流降为0。正弦电流波形中会包含2～4个小脉冲,脉冲正负交替呈现,持续时间约25μs;且在不同间隙宽度下放电电流波形频率集中在50 Hz。同时研究发现将时域和频域特征分析所得结果作为特征量,可以对间隙放电电流波形进行识别。研究结果可以为地线放电故障电流监测提供参考依据。

The decrease of the length of the ground insulator in parallel makes it easy to produce the gap breakdown discharge under the influence of high induction voltage,which directly threatens the safe operation of the power system.In order to know about the characteristics of ground insulator gap discharge waveform,the study of the gap discharge test on ground insulator with different gap is presented.The breakdown discharge current waveform was measured and its time and frequency domain characteristics were analyzed.The analysis results show that a large pulse is generated in the initial section of discharge current wave,and the pulse current amplitude reaches about 6 A.The sinusoidal current waveform appears after the large pulse current,and its current amplitude is about 0.25 A.After a sustained period of 1~2 cycles,the current drops to zero.The sinusoidal current waveform would contain 2~4 small pulses,with alternating periods of plus or minus.Moreover,the frequency of current waveform is concentrated at 50 Hz in different gap widths.At the same time,the results of time and frequency domain analysis can be used as the characteristic quantity to identify the gap discharge current waveform.The results can provide reference for fault current monitoring of ground discharge.