高压储能电容器的直流局放测试

针对直流电压从零加压到稳定的这一过程,提出直流局部放电的测试分为过渡区和平稳区两个阶段并根据被测试样电容器的参数,确定了相应的过渡区与平稳区的测试时间与方式,采用触发采集方式以适应直流条件下长时间采集的要求。过渡区测试时间为420s;平稳区每次测试时间为10min,测量10次,通过多次统计分析得出局部放电统计谱图。结果证明:两个阶段的统计结果不一样,能分别反映被测试样的缺陷特性。

Measurement of DC Partial Discharge of High-voltage Storage Capacitor

Insulation capability of high-voltage storage capacitor is important to the work reliability of impulse power system.The direct current partial discharge(DCPD) measurement is one of major insulation tests for the electrical instruments whose work processes are charged by direct current source and discharge with large impulse.The DCPD measurement process is divided into transition section and flat section.Because of the rise time of voltage,free electron was easy to occur as the main element for partial discharge.This effect will even continue to the inceptive period of steady value voltage.During the steady value,few change of voltage makes discharge difficult to take place.Based on the parameters of capacitors and actual test,the measurement time and method in the two sections can be determined.The measurement time of transition section is 420 s.Each measurement time in flat section is 10min,which should be repeated 10 times.As for the long-time acquisition demand,trigger acquisition way was brought out.Then PD spectrum was calculated by the multi-time statistic analysis technology.Experiments indicated that the partial discharge characteristics in two sections are different,including the maximal discharge magnitude,discharge number and the interval between adjacent discharges.They explained the respective characteristics of capacitors.The discharge results during transition section could illustrate the defect amount and dimension of small cavity.However,the discharge results on flat section could indicate the main defects geometry and insulation capability of material.