中文摘要：

直流局部放电测试是高压直流设备绝缘性能状态评估的主要手段之一。为掌握直流下局部放电波形的特性，对内部、表面、电晕3种典型缺陷的直流局部放电波形进行测试与分析。内部缺陷受放电电荷的反电场影响，在直流平稳区不能持续发生，断电后会出现反极性放电；表面放电与电晕放电均能在直流电压下稳定产生，却不能在断电后出现。分析直流电压下局部放电信号，3种放电脉冲的持续时间均有不同，且放电波形易叠加振荡。比较缺陷放电信号的频谱分析结果，3种放电的能量分别位于不同的区间，为直流下缺陷类型的识别奠定了基础。

英文摘要：

DCPD measurement is one of the insulation condition estimation methods on high voltage DC devices. To understand the characters of DCPD waveform, test and analysis were proceed on inner, surface and corona classical defects. Inner discharge can not happen continuously during flat period of DC voltage. But it will occur after cutting off the power. This is because of the inverse electrical field established by charge in defect. About surface discharge and corona discharge, they can happen stably under DC even after power off. It is found much difference among the three discharge signal waveforms. However surge easier on the waveform will affect the frequency spectrum analysis. Com- paring the frequency spectrum results of three defects, they have respective band range, which will do use to the defect type recognition under DC.