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双极MMC-HVDC系统站内接地故障特性及保护策略
作者:
作者单位:

1.国网冀北电力有限公司检修分公司,北京市 102488;2.国网冀北电力有限公司,北京市 100045;3.华北电力大学电气与电子工程学院,河北省保定市 071000

摘要:

针对双极柔性直流输电系统模块化多电平换流器(MMC)交直流出口接地故障,研究了换流器闭锁后的电压电流暂态特性,并推导了故障分量的数学解析式。研究结果表明,交流出口发生单相接地故障时,换流器闭锁后非故障相上、下桥臂分别出现了过电压和过电流现象,并且交流侧电流出现直流偏置导致故障相短路电流不存在过零点。直流出口发生单极接地故障,换流器闭锁后桥臂短路电流主要由交流系统注入的稳态电流和上下桥臂电抗间衰减的环流构成。针对交流出口发生单相接地故障这一特殊的故障特性,提出了一种选相跳闸保护策略,解决了故障电流不存在过零点时交流断路器无法正常断开的难题。最后搭建了张北四端环网结构柔性直流电网仿真模型,仿真结果验证了换流器出口故障特性分析的准确性以及所提选相跳闸保护策略的有效性和可行性。

关键词:

基金项目:

河北省自然科学基金资助项目(E2019502123)。

通信作者:

作者简介:

李振动(1984—),男,硕士,高级工程师,主要研究方向:柔性直流输电技术。E-mail: vibrateli@163.com
安海清(1990—),男,通信作者,硕士,工程师,主要研究方向:柔性直流输电技术、电能质量分析与控制。E-mail: 245932206@qq.com
樊小伟(1973—),男,硕士,高级工程师,主要研究方向:柔性直流输电技术。E-mail: yanshanzxf@163.com


Converter Grounding Fault Characteristics and Protection Strategy in Bipolar MMC-HVDC System
Author:
Affiliation:

1.Maintenance Branch of State Grid Jibei Electric Power Co., Ltd., Beijing 102488, China;2.State Grid Jibei Electric Power Co., Ltd., Beijing 100045, China;3.School of Electrical and Electronic Engineering, North China Electric Power University, Baoding 071000, China

Abstract:

In view of AC/DC outlet grounding faults of modular multilevel converter (MMC) in bipolar flexible high-voltage direct current (HVDC) transmission systems, the transient characteristics of voltage and current after converter fault blocking are studied. The mathematical analytical formula of the fault component is derived. The research results show that a single-phase grounding fault at the AC outlet will lead to the overvoltage and the overcurrent of the upper arm and the lower arm of blocked converter on the non-fault phase, respectively. And the DC bias on the AC-side current causes the fault phase short-circuit current to have no zero-crossing. When a pole-to-ground fault occurs at the DC outlet, the short-circuit current of the bridge arm of the blocked converter is mainly composed of the steady-state current injected by the AC system and the circulating current between the upper and lower arms. A phase-selective trip protection strategy is proposed for this special fault characteristic of single-phase grounding fault at AC outlet, which can solve the problem that the AC circuit breaker cannot be normally opened when the zero-crossing point of the fault current does not exist. A simulation model of the Zhangbei flexible DC grid of China is built. The simulation results show that the analysis of the fault characteristics at the converter outlet is accurate and the proposed phase-selective trip protection strategy is effective and feasible.

Keywords:

Foundation:
This work is supported by Hebei Provincial Natural Science Foundation of China (No. E2019502123).
引用本文
[1]李振动,安海清,樊小伟,等.双极MMC-HVDC系统站内接地故障特性及保护策略[J].电力系统自动化,2020,44(5):77-83. DOI:10.7500/AEPS20190715003.
LI Zhendong, AN Haiqing, FAN Xiaowei, et al. Converter Grounding Fault Characteristics and Protection Strategy in Bipolar MMC-HVDC System[J]. Automation of Electric Power Systems, 2020, 44(5):77-83. DOI:10.7500/AEPS20190715003.
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  • 收稿日期:2019-07-15
  • 最后修改日期:2019-12-03
  • 录用日期:
  • 在线发布日期: 2020-03-08
  • 出版日期:
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