计及控制策略影响的MMC-HVDC直流单极接地故障特性分析

doi:10.16180/j.cnki.issn1007-7820.2021.08.011

摘要/Abstract

摘要：

针对现有柔性直流输电系统单级接地故障特性未充分考虑换流器控制的问题,文中提出了一种计及控制策略影响的MMC-HVDC直流单极接地故障暂态特性分析方法。根据系统中性点的接地方式,建立直流侧单极接地故障后短路电流流通路径模型,再通过分析故障后最近电平逼近控制策略对故障路径中各物理参数的影响,从而揭示出故障极所在桥臂上子模块投切个数的变化规律。通过推导短路电流和子模块电容电压的计算公式,精确描述MMC-HVDC系统单极故障暂态过程。实时数字仿真系统的实验结果验证了短路电流及电容电压表达式的正确性。

关键词: 单极接地故障, 控制系统, 子模块电容电压, 短路电流, 接地方式, 流通路径, 最近电平逼近控制, 故障特性

Abstract:

At present, in order to solve the problem that the converter control is not fully considered in the single-stage ground fault characteristics of the existing flexible HVDC transmission system, this study proposes a transient characteristics analysis method for single-stage ground fault of MMC-HVDC system considering the influence of control strategy. According to the grounding mode of neutral point, the short circuit current path model after the single point grounding fault on DC side is constructed. By analyzing the influence of the nearest level control strategy on the physical parameters in the fault path, the change law of number of sub-modules on the bridge arms that locates on faulted pole is revealed. The formulas of short circuit current and capacitor voltage of sub-modules are derived, which accurately shows the transient characteristic of single point fault on DC side for MMC-HVDC system. The RTDS simulation results show the validity of formulas of short circuit current and capacitor voltage.

Key words: single-stage ground fault, control system, sub-module capacitor voltage, short-circuit current, grounding mode, circulation path, nearest level approximation control, fault characteristic

中图分类号:

TP11

时熙,程鹏. 计及控制策略影响的MMC-HVDC直流单极接地故障特性分析[J]. 电子科技, 2021, 34(8): 64-70.

SHI Xi,CHENG Peng. Analysis of MMC-HVDC DC Single Pole Grounding Fault Considering the Influence of Control Scheme[J]. Electronic Science and Technology, 2021, 34(8): 64-70.

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参数	数值
额定交流电压	25 kV
额定直流电压	±20 kV
桥臂子模块个数	10
桥臂电感	0.003 1 H
子模块电容	1 200 μF
输电线路电阻	0.033 Ω·km^-1
输电线路电抗	2.7 mH·km^-1
输电线路长度	200 km