矿用高压电缆局部放电测量传感器的研究及应用

Research and application of high-frequency current transformers for partial discharge measurement of mining cables

监测矿用高压电缆中局部放电信号对于在线评估电缆寿命和分析绝缘状况意义重大。对比了电缆绝缘监测的常用方法,其中采用高频电流传感器监测局部放电是一种有效手段。运用无损耗传输线理论建立了少匝数分裂式高频电流传感器的模型,分析了不同材料制作的传感器频率响应差异,测试了NiZn铁氧体高频电流传感器的幅频特性,并在不同匝数NiZn传感器和耦合电容情况下,分别测量和比较了基于针板电极下电树枝化试样的局部放电。实验结果表明:所研制的传感器能够测量放电量大于10 pC,频率范围在0.3~20 MHz的局部放电脉冲,具有在线测量矿用高压电缆局部放电的能力。

It is of a great significance to monitor the partial discharge( PD) of mining cables for evaluating cables' life and analyzing the insulation condition. Through briefly comparison of conventional methods to monitor the insulation states of mining cables in this paper,it is concluded that the high-frequency current transformer( HFCT) is an effective mean to measure PD pulses. A model of the split HFCT with a small number of turns was established based on the lossless transmission line. On this model,the frequency response of HFCT made from different materials was analyzed and then magnitude-frequency characteristics of NiZn HFCTs were experimentally tested. PD pulses of electrical treeing samples produced by the needle-plate electrode were measured by means of different NiZn HFCT and a coupling capacitance. Based on the comparison of the tested results,it is shown that HFCT can be used to measure the PD pulses which quantity is greater than 10 pC and frequency is the range from 300 kHz to 20 MHz and it also can be used to measure the insulation state of mining HV cables online.