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不对称双极多端柔性直流电网短路电流特性分析
作者:
作者单位:

1.临沂大学自动化与电气工程学院,山东省临沂市 276000;2.清华大学电机工程与应用电子技术系,北京市 100084;3.山东大学电气工程学院,山东省济南市 250061

作者简介:

通讯作者:

基金项目:

国家重点研发计划资助项目(2016YFB0900500)。


Characteristic Analysis on Short-circuit Current for Asymmetric Bipolar Modular Multilevel Converter Based Multi-terminal Direct Current Grid
Author:
Affiliation:

1.School of Automation and Electrical Engineering, Linyi University, Linyi 276000, China;2.Department of Electrical Engineering, Tsinghua University, Beijing 100084, China;3.School of Electrical Engineering, Shandong University, Jinan 250061, China

Fund Project:

This work is supported by National Key R&D Program of China (No. 2016YFB0900500).

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    摘要:

    含金属回线的不对称双极柔性直流电网的短路电流特性分析是其故障类型判别和故障隔离的基础。不对称双极电网发生各种故障时的短路电流具有相似的特性,难以区分。文中针对不对称双极多端直流电网的短路电流特性进行分析。首先,建立直流电网的等效电路,其中换流器和线路分别简化为RLC串联电路和RL串联电路;然后,基于建立的等效电路,分析了单端换流站的短路电流特性;最后,基于单端换流站短路电流特性,分析各换流站的放电回路,研究了不对称双极多端柔性直流电网在各种故障类型下的短路电流特性。张北双极柔性直流电网的仿真结果验证了分析得到的多端柔性直流电网短路电流特性的正确性。

    Abstract:

    Characteristic analysis on short-circuit current for asymmetric bipolar modular multilevel converter based multi-terminal direct current (MMC-MTDC) grid with dedicated metallic return (DMR) is the foundation of its fault type discrimination and fault isolation. The characteristics of short-circuit currents with different faults are similar, which makes them difficult to be distinguished. This paper analyzes the short-circuit current characteristics of asymmetric bipolar MTDC grids. First, the equivalent circuit of the MTDC grid is established, where the converter and overhead line are simplified to RLC series circuit and RL series circuit, respectively. Then, based on this, the short-circuit current characteristics of a single-terminal converter station are analyzed. Finally, the short-circuit current characteristics of the asymmetric bipolar MMC-MTDC grid following various faults are studied by analyzing the discharge circuit of MMCs based on the above short-circuit current characteristics of a single-terminal converter station. Test results on the Zhangbei bipolar MMC-MTDC grid validate the correctness of the characteristic analysis on short-circuit current for MMC-MTDC grids.

    表 1 Table 1
    表 8 Table 8
    表 9 Table 9
    表 4 Table 4
    表 2 Table 2
    图1 单端换流站极对极短路时的放电回路Fig.1 Discharge circuit of a single-ended converter station with pole-to-pole fault
    图2 直流线路i-j发生极对极短路时i侧网络的等效电路Fig.2 Equivalent circuit of network at i side when pole-to-pole fault occurring at the DC line i-j
    图3 线路2-3和1-4中点分别发生极对金属回线短路接地故障时的放电回路Fig.3 Discharge circuits of MMCs with pole-to-DMR-to-ground faults occurring at the midpoint of lines 2-3 and 1-4, respectively
    图4 线路2-3中点发生不同故障时的短路电流Fig.4 Short-circuit currents with different types of fault occurring at the middle of line 2-3
    图 MMC的结构及其等效电路Fig. Structure and equivalent circuit of an MMC
    图 直流架空线路用不同模型表示时的短路电流Fig. Short-circuit currents for a dc overhead transmission line when it is represented by different models
    图 单端换流站极对极故障时的等效模型Fig. Equivalent model of a single converter station under a pole-to-pole fault
    图 四端柔性直流电网示意图Fig. Schematic diagram of a four-terminal MTDC grid
    图 线路2-3发生不同故障时四端直流电网的等效电路及其放电回路Fig. Equivalent model and the discharge path of the four-terminal dc grid when different faults occur on line 2-3.
    图 线路发生极对地短路故障时的放电回路;(a)线路2-3中点;(b)线路1-4中点;Fig. Discharge paths of the MMCs under a pole-to-ground fault.
    图 线路2-3的末端分别发生极对极和正极极对金属回线故障时的短路电流Fig. Short-circuit currents under different types of faults that occur at the end of line 2-3.
    图 不同地点正极对金属回线短路接地时的短路电流Fig. Short-circuit currents under positive pole-to-DMR-to-ground faults that occur at different places.
    图 不同地点发生正极对地短路时的短路电流Fig. Short-circuit currents under positive pole-to-ground faults occurring at different places.
    图 线路2-3上不同位置发生不同故障时的电流i20pFig. Currents i20p when a dc fault occurs at different places of line 2-3.
    表 3 Table 3
    表 7 Table 7
    表 6 Table 6
    表 5 Table 5
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引用本文

何莉萍,高仕林,叶华.不对称双极多端柔性直流电网短路电流特性分析[J/OL].电力系统自动化,http://doi.org/10.7500/AEPS20190729014.
HE Liping,GAO Shilin,YE Hua.Characteristic Analysis on Short-circuit Current for Asymmetric Bipolar Modular Multilevel Converter Based Multi-terminal Direct Current Grid[J/OL].Automation of Electric Power Systems,http://doi.org/10.7500/AEPS20190729014.

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  • 收稿日期:2019-07-29
  • 最后修改日期:2020-04-15
  • 录用日期:2020-02-24
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