南方電網直流工程共用接地極的風險及影響分析
陳俊宇，張卓杰
(中國南方電網有限責任公司超高壓輸電公司廣州局，廣東 廣州 510663)
摘 要：對于共用接地極的直流系統，存在其中一回直流單極大地運行或存在入地電流時，另一回直流開展單極大地、金屬回線轉換的操作，在此過程中接地網過流則導致保護動作閉鎖, 運行極和接地極線路刀閘開斷能力不夠等系統問題和設備問題。研究了共用接地極情況下金屬、大地轉換過程中存在的風險，包括對設備選型和控制保護的影響，以及共用接地極入地電流在換流站的分流關系及形成的電位分布，明確共用接地極入地電流對換流站的人身和設備的安全影響，并指出了共用接地極在接地極線路檢修時對站內的影響。
關鍵詞：直流工程； 共用接地極；風險；影響
中圖分類號：TM744 文獻標識碼：A 文章編號：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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