考虑交直流侧协调的模块化多电平换流站直流线路保护方案  

DC line protection scheme for modular multilevel converter station considering coordination of AC and DC sides

作　　者：戴志辉[1] 朱惠君 苏怀波 刘雪燕 金丽萍[2] 陈曦[2] DAI Zhihui;ZHU Huijun;SU Huaibo;LIU Xueyan;JIN Liping;CHEN Xi(Hebei Key Laboratory of Distributed Energy Storage and Microgrid,North China Electric Power University,Baoding 071003,China;State Grid Baoding Power Supply Company,Baoding 071000,China)

机构地区：[1]华北电力大学河北省分布式储能与微网重点实验室,河北保定071003 [2]国网保定供电公司,河北保定071000

出　　处：《电力自动化设备》2019年第9期109-115,共7页Electric Power Automation Equipment

基　　金：国家自然科学基金资助项目（51877084）;国家重点研发计划项目（2016YFB0900203）;河北省自然科学基金资助项目（E2018502063）;中央高校基本科研业务费专项资金资助项目（2017MS096）~~

摘　　要：在换流站保护中,交直流保护之间往往缺乏配合,且存在直流保护的速动性难以满足要求、故障区域难以确定等难点。为此,根据模块化多电平换流器(MMC)闭锁前后直流二次谐波电流与交流负序电流特征,提出了换流站交直流故障辨识方法,可有效区分交、直流故障,确定故障区域。在此基础上,提出了交、直流侧协调配合的换流站直流保护方案。最后,结合光伏直流汇集接入系统的PSCAD/EMTDC模型,验证了交直流故障辨识方法的可行性以及交、直流侧协调配合的直流保护方案的可靠性。结果表明,所提方法能有效识别交、直流故障,且受过渡电阻的影响较小。In the protection of converter station, the coordination between AC and DC protections has not been fully addressed, and the tripping speed of DC protection is not quick enough and the fault area is difficult to be identified accurately. Therefore, an approach for discriminating AC and DC faults near MMC(Modular Multilevel Converter) station is proposed based on characteristics of DC-side second harmonic current and AC-side negative-sequence current before and after the blocking of MMC, which can effectively distinguish AC faults from DC ones and determine the fault area. On this basis, a DC protection scheme for MMC station considering the coordination between AC and DC side protections is proposed. Finally, the feasibility of the AC/DC fault discrimination approach and the reliability of the DC protection scheme considering the coordination between AC and DC side protections are verified by the PSCAD/EMTDC model of a photovoltaic grid-connected system. Results demonstrate that the proposed approach can discriminate AC and DC faults while being slightly affected by the transition resistance.

关 键 词：模块化多电平换流器 交直流故障识别 继电保护 保护配合 2次谐波 负序分量 

分 类 号：TM773[电气工程—电力系统及自动化] TM721.1