基于电流模量分析的MMC-MTDC系统直流输电线路故障识别

DC Transmission Line Fault Identification of MMC-MTDC System Based on Current Modulus Analysis

直流线路故障的快速、可靠识别是基于模块化多电平换流器(modular multilevel converter,MMC)的柔性多端直流输电(multi-terminal direct current,MTDC)系统发展的关键技术之一。通过分析柔性多端直流系统线路故障后电流的暂态特征,提出了一套基于单端电流模量分析的MMC-MTDC系统直流线路故障识别方案。该方案通过对电流一模故障分量动态偏差值极值极性与大小的检测实现了直流线路故障快速定位,并利用故障后电流零模故障分量的差异,从而实现了对故障极的快速判别。在PSCAD仿真平台上搭建了双极四端MMC型柔性直流电网的模型,通过仿真算例验证了该保护在不同故障位置和过渡电阻下均能快速、可靠地检测到直流线路故障并且准确识别故障极。

The fast and reliable identification of DC line faults is one of the key technologies for the development of flexible multi-terminal direct current (MTDC)systems based on modular multilevel converters (MMC).a DC grid fault identification scheme based on single terminal current modulus analysis is proposed by analyzing the transient characteristics of short-circuit faults in the line of flexible MTDC grids.The scheme realizes the rapid positioning of the DC line fault by detecting the polarity and magnitude of the dynamic deviation value of the current-mode fault component, and uses the difference of the current zero-mode fault component after the fault to realize the rapid determination of the fault pole.The four-terminal flexible DC grid model of the modular multilevel converter is built on the PSCAD simulation platform.The simulation example shows that the protection can detect the DC line fault quickly and reliably under different fault locations and transition resistances and accurately identify fault poles.