• CSCD核心库收录期刊
  • 中文核心期刊
  • 中国科技核心期刊

电力建设 ›› 2018, Vol. 39 ›› Issue (9): 39-46.doi: 10.3969/j.issn.1000-7229.2018.09.005

• 基于直流配电网的新能源汇集技术 栏目主持 王毅教授 • 上一篇    下一篇

交直流混联系统单极接地故障对变压器直流偏磁及电流差动保护的影响分析

戴志辉,苏怀波,王雪,焦彦军   

  1. 分布式储能与微网河北省重点实验室(华北电力大学),河北省保定市 071003
  • 出版日期:2018-09-01
  • 作者简介:戴志辉(1980),男,博士,副教授,主要研究方向为电力系统保护与安全控制; 苏怀波(1992),男,硕士研究生,主要研究方向为电力系统保护与控制; 王雪(1978),男,博士,讲师,主要研究方向为电力系统保护与控制; 焦彦军(1963),男,博士,教授,主要研究方向为电力系统保护与控制。
  • 基金资助:

    国家重点研发计划项目(2016YFB0900203);河北省自然科学基金项目(E2018502063);中央高校基本科研业务费资助项目(2017MS096)

Impact of Pole-to-ground Faults on Transformer DC Bias and Differential Current Protection in Hybrid AC/DC Power Systems

DAI Zhihui,SU Huaibo,WANG Xue,JIAO Yanjun   

  1. Key Laboratory of Distributed Energy Storage and Microgrid of Hebei Province(North China Electric Power University),Baoding 071003,Hebei Province,China
  • Online:2018-09-01
  • Supported by:
    This work is supported by National Key Research and Development Program of China(No. 2016YFB0900203),Hebei Natural Science Foundation of China(No. E2018502063) and Fundamental Research Funds for the Central University (No. 2017MS096).

摘要: 交直流混联系统发生单极接地故障时,会导致模块化多电平换流器(modular multilevel converter, MMC)交流出口电压出现直流偏置,若联接变压器采用Dyn11经电阻接地方式,当变压器接地电阻较小时,直流单极故障后产生的直流电流会流入变压器,导致变压器直流偏磁,出现励磁涌流并可能引起其差动保护误动。该文首先针对交直流混合配电网中YNd11型联接变压器及经不同电阻接地的Dyn11型联接变压器,分析了直流单极故障对其直流偏磁的影响,总结了影响因素。其次,以光伏直流接入系统为例,在PSCAD/EMTDC中建立混联系统模型,并在换流器出口设置单极接地故障,对理论分析的正确性进行了验证。最后,提出变压器出现直流偏磁时的应对措施,并针对单极接地故障与单相接地故障引起的保护误动作进行了分析,给出了识别策略。

关键词: 单极接地, 直流偏磁, 励磁涌流, 接地方式, 交直流混联系统

Abstract: Pole-to-ground faults in the hybrid AC/DC power system may result in DC-bias voltage on the AC side of the MMC converter. If the transformer is Dyn-11 connected with small grounding resistance, the DC current caused by the pole-to-ground fault would pass the transformer and lead to DC bias in magnetic field, which would further produce the magnetizing inrush current and the malfunction of differential current protection of transformers. In this paper, with respect to YNd-11 connected transformers and Dyn-11 connected transformers with different grounding resistance in hybrid AC/DC distribution grids, the impact of pole-to-ground faults on the DC bias of transformers are analyzed. Influencing factors are subsequently concluded. Secondly, as an example of hybrid AC/DC systems, the DC-access PV grid-connection system model is established in PSCAD/EMTDC to verify the correctness of the theoretical analysis. Finally, countermeasures for DC bias, as well as the identification of pole-to-ground fault and single-phase grounding fault are given after analyzing the protection misoperation caused by DC bias.

Key words: pole-to-ground fault, DC bias, the magnetizing inrush current, grounding mode, hybrid AC/DC power systems

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