MMC-HVDC系统直流侧非金属性短路故障电流计算方法

为研究基于模块化多电平换流器的高压直流输电(MMC-HVDC)系统直流侧短路电流的工程实用计算方法，基于金属性短路故障电流通用解析式，分析了MMC-HVDC系统发生非金属性短路故障时换流站放电电流的相互抑制作用以及放电回路的耦合机理，并基于所推导的解析表达式提出了故障电流的解耦计算方法。基于PSCAD/EMTDC对MMC-HVDC系统发生非金属性短路故障工况进行仿真分析，将仿真结果与解析计算值进行对比验证。搭建数字-物理混合仿真实验模型，在数字端和物理端分别设置短路故障，对比实验值与解析计算值。验证结果表明，所提故障电流计算方法能准确地表征MMC-HVDC系统直流侧非金属性短路故障电流的演变趋势。

Calculation method of nonmetallic short circuit fault current in DC side of MMC-HVDC system

To explore the practical engineering calculation method of DC side short circuit current of modular multilevel converter based high voltage direct current(MMC-HVDC) system, the mutual suppression of discharge current and coupling mechanism of discharge circuit under the condition of nonmetallic short circuit fault are analyzed based on the general analytical formula of metallic short circuit fault current. And the decoupling calculation method of short circuit current is proposed based on the deduced analytical formula. The nonmetallic short circuit fault condition of MMC-HVDC system is simulated based on PSCAD/EMTDC, and the simulative results are compared with the analytical calculation values. Meanwhile, a digital-physical hybrid simulation experiment model is established, and the short circuit faults are set at the digital and the physical terminals respectively to compare the experimental values with the analytical values. The verification results indicate that the proposed short circuit current calculation method can accurately characterize the current evolution trend of nonmetallic short circuit fault current in DC side of MMC-HVDC system.