中国电力科学研究院有限公司, 北京市 100192
China Electric Power Research Institute, Beijing 100192, China
In case of open-phase operation or asymmetric longitudinal fault occurring on one line of the multi-circuit transmission lines on the same tower, the zero-sequence directional protection of healthy lines with the same voltage on the same tower may mal-operate due to the zero-sequence voltage compensation. Zero-sequence voltage induced between the lines on the same tower with mixed voltages may also cause mal-operation. The electrical characteristics of asymmetric longitudinal faults and open-phase operation and the specific mechanism leading to mal-operation of zero sequence directional protection are analyzed. The influence of various factors on the process of mal-operation and the solution are discussed. A method for preventing mal-operation by extracting the states of transmission lines based on substation information is proposed. For multi-circuit transmission lines with the same voltage on the same tower, the method for preventing mal-operation by calculating the cross point of zero-sequence voltage and reversely compensating zero-sequence voltage is proposed. For multi-circuit transmission lines on the same tower with the mixed voltages, the method of identifying the failure characteristics of the lines based on the substation information and automatically blocking the zero-sequence directional protection is proposed. Real-time digital simulator(RTDS)is used to simulate the electrical characteristics of healthy lines and the mal-operation process when an asymmetric longitudinal/latitudinal fault occurs on multi-circuit transmission lines on the same tower under different work conditions. The effectiveness of the proposed method for preventing mal-operation is verified.
DAI Feiyang, WANG Xingguo, YANG Guosheng,et al.Substation Information Based Method for Preventing Mal-operation of Zero-sequence Directional Protection on Multi-circuit Transmission Lines on the Same Tower[J].Automation of Electric Power Systems,2019,43(13):131-138. DOI:10.7500/AEPS20180825004.