电缆绝缘检测用20kV超低频余弦方波电压源

Development of a Novel 20 kV Very Low Frequency Cosine-rectangular Voltage Generator for Insulation Testing of Power Cables

随着电力电子技术的发展,半导体开关器件越来越广泛地应用于电力设备高电压试验领域。基于一种新型高压半导体开关,设计并制作了一套全新的多功能电力电缆检测设备,即超低频余弦方波测试系统,其既可用于耐压试验,也可用于局部放电检测与定位,还可用于介质损耗测量。基于绝缘栅双极型晶体管(IGBT)芯片串联结构的半导体开关动作速度快,性能稳定可控。实验搭建的余弦方波系统可输出最高20 kV的超低频余弦方波电压,满足国际标准IEEE 400.2的要求。最后,使用设计好的系统对一段300 m有缺陷的电缆进行了局部放电测试,验证了设备的有效性。

This paper covers research and development efforts to develop, design and test a novel very low frequency cosine-rectangular voltage generator specialized not only for a withstand test,but also a partial discharge test of standard medium voltage crosslinked polyethylene power cables.The system schematic and operating principle of the proposed system are presented and described.A charging and discharging switch is developed by means of an insulated gate bipolar transistor（IGBT） series-connected semiconductor switch.A laboratory prototype is assembled and tested.Maximum output voltage of the proposed cosine-rectangular voltage generator is measured as 20 kV,which is in accordance with the expected acceptance test voltage level given in standard IEEE 400.2.Finally,the proposed system is applied to partial discharge detection of a 300 m cable circuit with a built-in artificial defect, and the partial discharge locating results are presented, proving the system＇s feasibility.