XLPE绝缘电老化中局放特性试验研究

利用TE571局放检测仪和超宽频带局放(PD)检测系统研究了XLPE电缆绝缘试样加速电老化过程中判断试样老化状态的局放统计参量和单次放电波形特性。结果表明,电老化过程中单次放电时域波形的上升沿变陡,从老化前50 ns降低为老化50 h的8 ns;脉冲幅值从老化前的2 mV增加到老化50 h的17 mV;放电频谱中特征峰的位置随着老化程度的加剧向高频方向移动,从老化前<15 MHz增加到老化50 h的<50 MHz和125~200MHz。该研究为放电单次波形检测技术评估XLPE电力电缆绝缘状态的基础研究。

Experimental Study on Partial Discharge in XLPE Insulation During Electrical Aging

The XLPE insulation samples are processed by an accelerated electrical ageing setup,and the characteristics of partial discharges(PD) during ageing are studied by the TE571 PD detector and the ultra-wide band PD measurement system.The TE571 PD detector detects the phase resolved PD signals,such as the phase resolved distribution of the maximum discharge magnitude,the mean discharge magnitude,and the number of discharges,while the ultra-wide band PD measurement system acquires the time-domain pulses of PD and obtains the PD waveform parameters,such as the rise times,fall times,and amplitudes of PD pulses.Thus,the statistical parameters and single waveform parameters are obtained respectively,and the former can also be used to evaluate the aging status of the XLPE samples.The experimental results show that the rising edge of PD pulses become steep,which decreases from 50ns before aged to 8ns after aged for 50 hours,the amplitude of PD pulses increases from 2mV to 17mV,and the characteristic peaks location in the spectrum move toward to high frequency band,which shift from below 15MHz before aged to 50MHz and 125~200MHz.This research is a foundation for evaluating the insulating status of XLPE power cables in service.