基于改进时域法的多端MMC-HVDC故障电流计算
摘要：为解决基于模块化多电平换流器 (modular multilevel converter，MMC) 的柔性直流输电 (high voltage direct current，HVDC) 故障电流解析计算精度不足的问题，提出一种计及远端站影响的多端MMC-HVDC故障电流改进时域求解法。首先，在分析故障后子模块电容放电路径的基础上，推导换流站等效电容值等系统参数，建立MMC-HVDC系统故障后网络等效模型。其次，将直流电网各换流站解耦，以故障后各支路电流近似解为初值，逐次修正计及远端站影响的多端MMC-HVDC线路等效电阻及等效电感，得到多端MMC-HVDC系统中各支路的故障电流值。最后，基于RT-LAB仿真平台搭建四端柔性直流电网模型，对故障电流计算值与详细电磁暂态仿真结果进行对比。结果表明，所提故障电流求解方法能够准确、有效地计算出多端MMC-HVDC短路故障后各支路电流值，最大误差小于5%。
Abstract:In view of the insufficient analytic calculation accuracy of the fault current in modular multilevel converter based flexible multi-terminal high voltage direct current (MMC-HVDC) transmission system, an improved time-domain solving method taking the influence of the converter stations located at far-end into account was proposed. Firstly, on the basis of analyzing the discharging path of the capacitor in the post-fault submodule, the systemic parameters such as the value of the equivalent capacitance in converter station and so on were derived, and an equivalent network model of the post-fault MMC-HVDC system was built. Secondly, decoupling the converter stations in DC network and taking the approximate solutions of post-fault currents in all branches as the initial values, the equivalent resistances and equivalent inductances of the lines in multi-terminal MMC-HVDC network were successively revised while the influences of far-end converter stations were taken into account, and then the values of fault currents of the lines in MMC-HVDC system were obtained. Finally, based on RT-LAB simulation platform a four-terminal flexible DC network model was constructed, by which the calculated values of fault currents and the simulation results of detailed electromagnetic transient were contrasted. Contrast results show that by use of the proposed solving method for fault currents, the values of currents after the short circuit fault in all branches of multi-terminal MMC-HVDC network can be effectively calculated, and the maximum error is less than 5%.
标题：基于改进时域法的多端MMC-HVDC故障电流计算
英文标题：An Improved Time Domain Method Based Fault Current Calculation for Multi Terminal MMC-HVDC Transmission System
作者：冯智博, 辛业春, 李国庆,
关键词：模块化多电平换流器(MMC), 柔性直流电网, 线路故障, 改进时域求解法, 短路电流计算,
发表日期：2020-12-10
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