柔性直流输电对交流系统负序方向元件影响分析

摘要

介绍了柔性直流换流器等效模型,分析了负序方向元件在含柔性直流系统的交流系统电网中的适应性,并通过仿真研究对理论分析进行了验证,提出了保护配置建议.仿真结果表明,交流电网不对称故障时基于负序方向元件的纵联保护可能拒动或误动,对柔性直流换流站出线不宜采用基于负序方向元件的纵联保护.%The equivalent models of voltage source converter based high voltage direct current (VSC-HVDC) are described.The model of the negative sequence directional component is built, and the adaptability of the negative sequence directional component applied in the hybrid power grid of VSC-HVDC and AC power grid is analyzed in theory.The theoretical analysis is verified by simulation and suggestions for protection configuration are provided.The theoretical analysis and simulation results demonstrate that the positive and negative current decoupled controller can restrain negative fault current and have a good performance in fault ride through.The negative sequence directional component may refuse to trip when the AC power grid is unbalanced.The negative sequence directional component is inapplicable to the outgoing line of VSC-HVDC station.