南方电网直流工程共用接地极的风险及影响分析
陈俊宇，张卓杰
(中国南方电网有限责任公司超高压输电公司广州局，广东 广州 510663)
摘 要：对于共用接地极的直流系统，存在其中一回直流单极大地运行或存在入地电流时，另一回直流开展单极大地、金属回线转换的操作，在此过程中接地网过流则导致保护动作闭锁, 运行极和接地极线路刀闸开断能力不够等系统问题和设备问题。研究了共用接地极情况下金属、大地转换过程中存在的风险，包括对设备选型和控制保护的影响，以及共用接地极入地电流在换流站的分流关系及形成的电位分布，明确共用接地极入地电流对换流站的人身和设备的安全影响，并指出了共用接地极在接地极线路检修时对站内的影响。
关键词：直流工程； 共用接地极；风险；影响
中图分类号：TM744 文献标识码：A 文章编号：1007-3175(2021)11-0019-04
Analysis on the Risks and Impact of Common Grounding Electrodes in the
DC Project of China Southern Power Grid
CHEN Jun-yu, ZHANG Zhuo-jie
（EHV Power Transmission Company Guangzhou Bureau of China Southern Power Grid, Guangzhou 510663, China）
Abstract: There are systemic and mechanic problems that exist in the common ground electrode of the DC system. For the DC system that shares the grounding electrode, when one of the DC units is in monopole-ground operation mode, or there is a current in the earth, the other DC is developing single-pole earth or metal loop operation. During the conversion operation, the overcurrent of the grounding grid will cause the protection action to block the running pole and the grounding pole circuit breaker and other system problems and equipment problems such as insufficient breaking capacity. This paper studies the risks in the conversion process between metal and earth in the case of shared grounding electrodes, including the impact on equipment selection and control protection. Besides, it discusses the shunting relationship of the current into the ground of the common grounding electrode in the converter station and the result of electric potential distribution. Moreover,it clarifies the impact of the common grounding electrode current on the operator and the equipment of the converter station. Finally, it figures out the influence of the common grounding electrode on the station during the maintenance of the grounding electrode line.
Key words: DC project; common grounding electrode; risk; impact
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