LCC‑HVDC逆变侧换流站近区交流线路高阻接地故障保护

High Resistance Grounding Fault Protection of AC Line Near Converter Station at Inverter Side of LCC-HVDC

基于电网换相换流器的高压直流(LCC-HVDC)换流站近区交流线路高阻接地故障切除不及时易引发连续或后续换相失败,造成换流站单双极闭锁,威胁着系统运行安全性。文中分析了影响零序差动保护动作特性的关键因素,指出高阻接地故障保护需从传统的阈值整定模式调整为对被保护线路故障支路特性变化的定性描述和甄别。基于弧光高阻接地故障支路的非线性伏安特性辨识以及同塔并架相邻线路广域方向信息的配合,提出了适用于LCC-HVDC换流站近区交流线路的高阻接地故障启动元件、方向元件及保护方案。最后,通过仿真验证了保护方案的有效性。

Failure to remove the high resistance grounding fault of an AC line near a converter station of line commutated converter based high voltage direct current(LCC-HVDC)in time may easily cause continuous and subsequent commutation failures,resulting in unipolar and bipolar blocking of the converter station,threatening the operation safety of the system.This paper analyzes the key factors that affect the operation characteristics of zero-sequence differential protection,and points out that the high resistance grounding fault protection needs to be adjusted from the traditional threshold setting mode to the qualitative description and discrimination of the characteristics of the fault branch of the protected line.Based on the nonlinear volt-ampere characteristic identification of arc high resistance grounding fault branch and the cooperation of wide-area direction information of adjacent lines on the same tower,the high resistance grounding fault starting element,directional element and protection scheme suitable for AC lines near converter station of LCC-HVDC are proposed.Finally,the effectiveness of the protection scheme is verified by simulation.