Analysis of the influence of non-full-phase operation on line zero-sequence current protection
DOI:DOI: 10.19783/j.cnki.pspc.211662
Key Words:non-full-phase operation  line zero-sequence current protection  setting calculation  zero-sequence branch coefficient  override
Author NameAffiliation
HAO Yihua 1. State Key Laboratory of Advanced Electromagnetic Engineering and Technology (Huazhong University of Science and Technology), Wuhan 430074, China
2. China Southern Power Grid Power Dispatching and Control Center, Guangzhou 510663, China
3. Liupanshui Power Supply Bureau, Guizhou Power Grid Co., Ltd., Liupanshui 553001, China 
CHEN Zhao 1. State Key Laboratory of Advanced Electromagnetic Engineering and Technology (Huazhong University of Science and Technology), Wuhan 430074, China
2. China Southern Power Grid Power Dispatching and Control Center, Guangzhou 510663, China
3. Liupanshui Power Supply Bureau, Guizhou Power Grid Co., Ltd., Liupanshui 553001, China 
huiHE Jinfeng 1. State Key Laboratory of Advanced Electromagnetic Engineering and Technology (Huazhong University of Science and Technology), Wuhan 430074, China
2. China Southern Power Grid Power Dispatching and Control Center, Guangzhou 510663, China
3. Liupanshui Power Supply Bureau, Guizhou Power Grid Co., Ltd., Liupanshui 553001, China 
LI Yinhong 1. State Key Laboratory of Advanced Electromagnetic Engineering and Technology (Huazhong University of Science and Technology), Wuhan 430074, China
2. China Southern Power Grid Power Dispatching and Control Center, Guangzhou 510663, China
3. Liupanshui Power Supply Bureau, Guizhou Power Grid Co., Ltd., Liupanshui 553001, China 
SHI Dongyuan 1. State Key Laboratory of Advanced Electromagnetic Engineering and Technology (Huazhong University of Science and Technology), Wuhan 430074, China
2. China Southern Power Grid Power Dispatching and Control Center, Guangzhou 510663, China
3. Liupanshui Power Supply Bureau, Guizhou Power Grid Co., Ltd., Liupanshui 553001, China 
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Abstract:Non-full-phase operation is a common asymmetric operational state in a power system. It will affect line zero-sequence current protection, causing it to lose selectivity and override. Therefore, the setting calculation principle of line zero-sequence current protection is studied. Then the calculation formulas of the zero-sequence branch coefficient under short-circuit fault and non-full-phase operation are deduced. By comparing the calculation formula of zero-sequence branch coefficient in two cases, the reason for the override of zero-sequence current protection under non-full-phase operation is analyzed. Compared with the zero-sequence branch coefficient of a short-circuit fault, the greater the zero-sequence branch coefficient of non-full-phase operation is, the easier the occurrence of override. Combined with the example of the IEEE39 bus system, it is verified that the increase of zero-sequence branch coefficient may cause the line zero-sequence current protection to override in the condition of non-full-phase operation. Finally, given the problem that zero-sequence current protection may override during non-full-phase operation, coping strategies are given from the two aspects of settings off-line verification and on-line management. This work is supported by the National Key Research and Development Program of China (No. 2016YFB0900100).
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