特高压半封闭气体绝缘组合电器的暂态电压仿真分析

特高压系统的电压等级高、容量大,暂态电压现象严重。为了提高特高压系统暂态电压计算的准确率,结合我国某特高压开关站建立半封闭气体绝缘组合电器(HGIS)系统整体模型。根据多导体传输线理论和相模变换方法,建立了HGIS外壳传输特性模型。除此之外,采用π型等效电路表示接地体单元,并结合HGIS内部暂态模型,详细计算了隔离开关操作时产生的特快速瞬态过电压(VFTO)和暂态壳体电压(TEV),分析了HGIS内部关键设备处VFTO和相应壳体上TEV的最大值和频谱特性,进一步分析了不同壳体接地方式和接地网对VFTO和TEV的影响。研究结果表明:在考虑接地网的情况下,VFTO的最大值为1 296kV,TEV的最大值为83kV,都要比不考虑接地网时的最大值小,且良好的接地方式是降低特高压HGIS系统暂态电压的有效方法。研究结果可供HGIS设计和相关电气设备绝缘结构设计参考。

Simulation Analysis on Transient Voltage of UHV Hybrid Gas Insulated Switchgear

In order to improve the accuracy of calculation of UHV system transient voltages,taking ultra-high voltage switching substation in China as example,we established a model symbolizing the transmission characteristics of hybrid gas insulated switchgear(HGIS) enclosure on the basis of theory of the multi-conductor transmission lines and phase-mode transformation method.In addition,using π-type equivalent circuit to express grounding unit and combining with internal HGIS transient model,we calculated the very fast transient over-voltage(VFTO) and transient enclosure voltage(TEV) produced by operation of disconnector.On the one hand,we analyzed VFTO of key equipment at HGIS and the maximum values and spectral characteristics of TEV,on the other hand,we analyzed the effects of different shell grounding and grounding network on the TEV and VFTO.The results show that,while considering the case of grounding network,the peak value of VFTO is 1 296 kV,and the peak value of TEV is 83 kV,which are lower than those without considering grounding network.A proper grounding is effective way to reduce the transient voltage of UHV HGIS system.The calculation and research results could be used as reference for electrical design of HGIS and relative electric devices.