WU Yekai,ZHAO Zhihong,NIE Juanhong,et al.Impact of Secondary Neutral Line Disconnection in Current Transformer on Transmission Line Differential Protection and Preventive Measures[J/OL].Automation of Electric Power Systems, http://dx.doi.org/10.7500/AEPS20250608002.
WU Yekai,ZHAO Zhihong,NIE Juanhong,et al.Impact of Secondary Neutral Line Disconnection in Current Transformer on Transmission Line Differential Protection and Preventive Measures[J/OL].Automation of Electric Power Systems, http://dx.doi.org/10.7500/AEPS20250608002.DOI:
Impact of Secondary Neutral Line Disconnection in Current Transformer on Transmission Line Differential Protection and Preventive Measures
The reliable identification of secondary neutral line disconnection of current transformers in line protection remains imperfect. Based on the characteristic that secondary neutral line disconnection significantly affects the zero-sequence current but has little influence on the positive- and negative-sequence currents
a method is proposed in which the original pilot differential protection is enabled through positive- and negative-sequence differential protection elements
thereby preventing maloperation during external asymmetric ground faults and incomplete-phase conditions. According to the characteristics of the composite sequence network
a phase-region identification element for internal single-phase ground faults is proposed to prevent three-phase tripping caused by an internal single-phase fault after secondary neutral line disconnection
which would otherwise initiate three-pole tripping and block reclosing. A method for determining whether the fault current has been cleared is also proposed by identifying the return of both positive- and negative-sequence differential protection elements
which eliminates the defect whereby the original protection cannot retract the trip command even after single-phase tripping
resulting in delayed three-phase tripping and failure of reclosing. Simulation tests and practical case verification show that the proposed method can prevent protection maloperation and provide alarm information for secondary neutral line disconnection anomalies.
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references
黄少锋 . 电力系统继电保护 [M]. 北京 : 中国电力出版社 , 2015 .
Huang Shaofeng . Relay protection for power systems [M]. Beijing : China Electric Power Press , 2015 .
朱声石 . 高压电网继电保护原理与技术 [M]. 北京 : 中国电力出版社 , 2005 .
Zhu Shengshi . Principles and technology of relay protection for high voltage power grids [M]. Beijing : China Electric Power Press , 2005 .
景敏慧 . 电力系统继电保护动作实例分析 [M]. 北京 : 中国电力出版社 , 2012 .
Jing Minhui . Analysis of relay protection operation cases in power systems [M]. Beijing : China Electric Power Press , 2012 .
Wei Lin , Zhang Jiankang , Su Xiaohua , et al . Analysis and countermeasures for line protection mal-operation caused by current secondary circuit defects [J]. Automation of Electric Power Systems , 2019 , 43 ( 19 ): 194 - 199 .
Li Xianglin . Analysis of influence of current transformer N phase break line on differential protection action of main transformer [J]. Modern Information Technolog , 2022 , 6 ( 17 ): 48 - 52 .
Li lei , Zhou Pengpeng , Li Zhiyong , et al . Dynamic simulation test on neutral line disconnection of secondary circuit of current transformer [J]. Guangdong Electric Power , 2022 , 35 ( 3 ): 88 - 98 .
Wang Yucai , Li Zhiyuan , Li Fei , et al . Development and application of online detection device for hidden defects in current circuits [J]. Ningxia Electric Power , 2023 ( 5 ): 45 - 50 .
Huang Shaofeng , Chen Bowei , Wu Yekai . Influence of increase of neutral line resistance in current transformer on line differential protection [J]. Automation of Electric Power Systems , 2017 , 41 ( 23 ): 77 - 82 .
Yuan Yubo , Wu Xuefeng , Deng Jieqing , et al . Current transformer phase-to-phase current interaction impact on differential protection schemes [J]. Automation of Electric Power Systems , 2010 , 34 ( 21 ): 65 - 69 .
Dai Zhihui , Zhang Fuze , Yang Xin , et al . Intelligent comparison method for fault record waveform data based on the FDTW algorithm [J] Power System Protection and Control , 2023 , 51 ( 23 ): 82 - 91 .