1. 南京南瑞继保电气有限公司, 江苏省南京市 211102; 2. 国家电网公司华中分部, 湖北省武汉市 430077
1. NR Electric Co. Ltd., Nanjing 211102, China; 2. Central China Branch of State Grid Corporation of China, Wuhan 430077, China
目前高压/特高压直流输电工程中基于行波等原理的直流线路快速保护的耐高阻能力不强，而针对高阻接地故障的基于差动等原理的慢速保护的动作速度又很慢。交流线路保护中靠近电源侧的前加速先无选择性地快速动作，而后再通过重合闸来纠正这种非选择性动作。文中将前加速概念引入直流输电线路快速保护中，达到直流线路故障下保护既快速又能适应高阻接地的目的；先动作移相而后通过闭锁等措施来纠正这种非选择性动作。分析了增加前加速段后需要考虑的问题，对故障过渡电阻阻值进行了估算。仿真验证显示线路末端500 Ω接地故障约2 ms动作时区分区外故障仍然存在较大的裕度。
At present, the travelling wave principle based DC line fast protection used in high voltage direct current(HVDC)/ultra-high voltage direct current(UHVDC)projects has the shortcoming of low ability of enduring transition resistance. And the differential principle based slow-speed protection for DC line grounding fault with high transition resistance usually trips slowly. In the AC line protection, a pre-acceleration used in near power side can trip fast without any selection. Then this non-selective trip can be rectified by reclosing breaker. This paper introduces the concept of pre-acceleration into DC line fast protection and aims to fast protect DC line under grounding fault with high transition resistance. The DC line pre-acceleration can trip fast without any selection, and then this non-selective trip can be rectified by several measures such as blocking converter. This paper analyzes several problems after introducing pre-acceleration into DC line protection, and estimates the value of transition resistance under the fault. The simulation verification shows that the DC line protection with pre-acceleration level can trip and have a margin to distinguish the fault in outside zone within 2 ms under line-end grounding fault with 500 Ω transition resistance.
WANG Junsheng,LIU Huanzhang.Pre-acceleration of Protection for HVDC Transmission Lines[J].Automation of Electric Power Systems,2019,43(9):1-8. DOI:10.7500/AEPS20190102001.