基于相模变换的柔性直流电网短路故障电流计算  

A method for short-circuit fault current calculation in DC grids based on phase-mode transformation

作　　者：王泰基 张坤 许壮 郭彦勋 WANG Taiji;ZHANG Kun;XU Zhuang;GUO Yanxun(Guoneng Shendong Coal Group Co.,Ltd.,Ordos 017209,China;Xuji Electric Co.,Ltd.,Xuchang 461000,China;School of Electrical and Information Engineering,Zhengzhou University,Zhengzhou 450001,China)

机构地区：[1]国能神东煤炭集团有限责任公司,内蒙古鄂尔多斯017209 [2]许继电气股份有限公司,河南许昌461000 [3]郑州大学电气与信息工程学院,河南郑州450001

出　　处：《电力工程技术》2024年第5期247-255,共9页Electric Power Engineering Technology

基　　金：国家自然科学基金资助项目(52107130)。

摘　　要：精确的短路故障电流计算对柔性直流电网的器件选型、参数设计以及继电保护研究十分重要。针对现有短路故障电流计算方法未充分考虑直流线路极间耦合的问题,文中提出一种基于相模变换的柔性直流电网短路故障电流计算方法。首先,建立换流站与直流线路的故障等值模型;然后,利用相模变换实现柔性直流电网正极与负极的电气解耦,并获取柔性直流电网在模域内的节点阻抗矩阵;接着,结合柔性直流电网的故障边界条件,计算出柔性直流电网短路故障电流的复频域值,并利用矢量拟合得到故障电流的时域值;最后,利用PSCAD/EMTDC仿真验证所提故障电流计算方法的有效性。仿真分析结果表明,在直流电网发生故障且换流站尚未过流闭锁期间,所提故障电流计算方法能够精准描述直流故障电流的变化规律。Accurate short-circuit fault current calculation is important for device selection,parameter design and protection research of flexible DC grid.To solve the problem that existing fault current calculation methods do not consider the pole-to-pole coupling of DC lines,a short-circuit fault current calculation method based on phase-mode transformation is proposed.First,the equivalent fault models of the converter station and DC line are established.Then,the phase-mode transformation is used to achieve electrical decoulping of positive and negative poles,and the node impedance matrix of the DC grid in the mode-domain is obtained.Subsequently,combining the fault boundary conditions of the DC grid,the fault current of the DC grid is calculated in the complex frequency-domain,and the fault current in the time-domain is obtained by using vector fitting.Finally,the proposed fault current calculation method is verified by PSCAD/EMTDC.The simulation results show that the proposed method can accurately calculate the DC fault currents after the DC fault occurs and before the converter station blocks.

关 键 词：柔性直流电网 故障电流计算 换流站 相模变换 故障边界条件 故障等值模型 

分 类 号：TM721[电气工程—电力系统及自动化]