When a pole-to-pole short-circuit fault occurs in an LCC-MMC hybrid DC transmission system, the fault characteristics are affected by the distributed capacitance and the transition resistance that cause a dead zone in the fault location and poor accuracy in determining the fault location. In view of this, this paper proposes a fault location method for the LCC-MMC hybrid DC transmission system. By analyzing the fault characteristics of the rectifier station and inverter station, the fault circuit equation of the rectifier side is analyzed, and the relationship between the fault distance and the transition resistance is deduced. The fault circuit of the inverter side is isolated by blocking CDSM-MMC, which can clear the fault current on the inverter side and thus eliminate the influence of the transition resistance. The steady-state fault information of the LCC DC outlet is used to eliminate the effect of distributed capacitance and achieve an accurate fault location. The LCC-MMC hybrid DC transmission system model is built on the PSCAD / EMTDC simulation platform. Simulation results show that the proposed fault location method can effectively avoid the transition resistance and distributed capacitance influences and thus obtain high fault location accuracy. Moreover, an accurate fault location can be achieved with a narrow fault data window length.

中文翻译：

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LCC-MMC混合直流输电系统极间短路故障定位方法研究

LCC-MMC混合直流输电系统发生极间短路故障时，故障特性受分布电容和过渡电阻的影响，导致故障定位盲区和判断精度差。故障位置。鉴于此，本文提出了一种LCC-MMC混合直流输电系统的故障定位方法。通过分析整流站和逆变站的故障特性，分析整流侧故障电路方程，推导出故障距离与过渡电阻的关系。通过阻断CDSM-MMC来隔离逆变侧的故障电路，可以清除逆变侧的故障电流，从而消除过渡电阻的影响。利用LCC直流插座的稳态故障信息，消除分布电容的影响，实现准确的故障定位。LCC-MMC混合直流输电系统模型建立在PSCAD/EMTDC仿真平台上。仿真结果表明，所提出的故障定位方法可以有效避免过渡电阻和分布电容的影响，从而获得较高的故障定位精度。此外，可以通过窄的故障数据窗口长度实现准确的故障定位。仿真结果表明，所提出的故障定位方法可以有效避免过渡电阻和分布电容的影响，从而获得较高的故障定位精度。此外，可以通过窄的故障数据窗口长度实现准确的故障定位。仿真结果表明，所提出的故障定位方法可以有效避免过渡电阻和分布电容的影响，从而获得较高的故障定位精度。此外，可以通过窄的故障数据窗口长度实现准确的故障定位。