后续换相失败引发的换流变零序差动保护误动场景分析及策略  

Analysis of mal-operation scenarios of zero-sequence differential protection of converter transformer caused by subsequent commutation failure and corresponding strategy

作　　者：翁汉琍[1] 王胜 饶丹青 郑玉民 李振兴[1] 黄景光[1] WENG Hanli;WANG Sheng;RAO Danqing;ZHENG Yumin;LI Zhenxing;HUANG Jingguang(Hubei Key Laboratory of Cascaded Hydropower Stations Operation&Control,China Three Gorges University,Yichang 443002,China;Jiujiang Power Supply Company,State Grid Jiangxi Electric Power Co.,Ltd.,Jiujiang 332000,China;Hanjiang Water Conservancy and Hydropower(Group)Co.,Ltd.,Wuhan 430048,China)

机构地区：[1]三峡大学梯级水电站运行与控制湖北省重点实验室,湖北宜昌443002 [2]国网江西省电力有限公司九江供电分公司,江西九江332000 [3]汉江水利水电(集团)有限责任公司,湖北武汉430048

出　　处：《电力自动化设备》2021年第3期64-70,共7页Electric Power Automation Equipment

基　　金：国家自然科学基金资助项目(51607106);国家留学基金资助项目(201908420183)。

摘　　要：发生后续换相失败后直流接地极入地电流经地网耦合与大直流共同入侵换流变压器中性线,分析了该工况下换流变压器中性线零序电流的特征及其对换流变中性线零序电流互感器传变特性的影响,并探讨了该工况下换流变零序差动保护的误动风险。利用细化的快速傅里叶变换对零序差动电流的幅频特征进行细分,将零序差动电流在低频频带与工频频带的幅值之比作为辅助判据,识别所讨论的工况,闭锁零序差动保护。仿真结果表明,所提策略能有效防止所讨论的工况引发的换流变零序差动保护误动作。The grounding electrode’s ground current caused by subsequent commutation failure is coupled by grounding network and then intrudes into the neutral line of converter transformer with large DC current.The characteristics of zero-sequence current of the converter transformer’s neutral line and its influence on the transmission characteristics of zero-sequence CTN(Current Transformer of Neutral line)of converter transformer under this condition are analyzed.The mal-operation risk of the zero-sequence differential protection under the discussed condition is studied as well.The ZOOM-FFT(ZOOM of Fast Fourier Transform)is used to subdivide the amplitude frequency characteristics of the zero-sequence differential current,and the ratio between the amplitude of zero-sequence differential current in low frequency band and that in power frequency band is applied as an auxiliary criterion to identify the discussed condition,and block zero-sequence differential protection.The simulative results indicate that the proposed strategy can effectively prevent the mal-operations of zero-sequence difference protection caused by the discussed condition.

关 键 词：高压直流输电 后续换相失败 换流变压器 零序差动保护 细化的快速傅里叶变换 

分 类 号：TM77[电气工程—电力系统及自动化]