基于VSC的直流电网输电线路单极接地故障分析
摘要：研究单极接地故障的故障特性对解决直流输电系统故障诊断、保护设计等关键问题具有重要意义。本文将直流输电系统的单极接地故障过程分为直流侧电容放电、网侧电流回馈和电压恢复3个阶段,并针对不同接地阻抗情况下系统暂态特性,推导出各故障过程中的电容电压和放电电流的时域表达式。通过分析故障过程中直流电压的振荡特性,直流系统可通过增加阻尼避免因网侧电流回馈导致该阶段二极管过流击穿。对于单极接地故障,直流系统可通过非故障相单极运行,使其在电压恢复阶段具备短时持续运行能力,为故障清除争取时间。通过搭建两端VSC-HVDC仿真系统,对直流系统的单极故障特性进行验证。
Abstract:A detailed analysis of the pole-to-ground fault characteristic is of great practical significance for solving such key problems as fault diagnosis and protection design of DC transmission system. In this paper, the pole-to-ground fault process of DC transmission system is divided into three stages, which are DC-side capacitor discharge, grid-side current feedback and voltage recovery. According to system transient characteristic under different grounding impedance, the time-domain expressions of capacitor voltage and discharge current in each stage are derived. By analyzing the oscillation characteristic of the DC voltage in the fault process, the increasing of damping for DC system can avoid the current feedback at grid-side that can make the diode breakdown in this stage. For pole-to-ground fault, the system can operate continuously through the single non-fault-phase, which makes it have the ability of short-time continuous operation during voltage recovery stage to support for fault clearing. In the end, the characteristic of pole-to-ground fault of DC system is testified through a two-terminal VSC-HVDC transmission system.
标题：基于VSC的直流电网输电线路单极接地故障分析
英文标题：Pole-to-ground Fault Analysis of Transmission Lines in VSC Based DC Power Grids
作者：张紫光, 付 媛, 王 毅,
关键词：直流输电, 直流线路故障, 单极接地故障, 故障特性, 故障分析,
发表日期：2017-02-09
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