基于故障电流传播特性的高压直流输电线路单端保护方案

Single-end protection scheme for HVDC transmission line based on fault current propagation characteristics

针对高压直流输电线路现有行波保护故障识别准确率不高、耐过渡电阻能力不强等问题,提出一种基于故障电流传播特性的单端保护方案。基于高压直流输电系统的等效电路,分别分析故障电流从换流侧到线路、从线路到换流侧以及在线路上的传播特性,进而分析不同位置发生故障时整流站线路边界两侧故障电流特征的差异性。基于此,利用特征频段电流构造区内、区外故障的识别判据,设计直流线路单端保护方案。基于PSCAD /EMTDC软件的仿真结果表明,所提保护方案能够准确识别区内、外故障,且具有良好的耐过渡电阻及抗噪声干扰能力。

Aiming at the problems of low fault identification accuracy and poor transition resistance tole-rance of existing traveling wave protections for HVDC(High Voltage Direct Current) transmission lines, a single-end protection scheme based on fault current propagation characteristics is proposed. Based on the equivalent circuit of HVDC transmission system, the propagation characteristics of fault current from the commutation side to the line, from the line to the commutation side and in the line are analyzed respec-tively, and then the differences of fault current characteristics on both sides of the line boundary of the recti-fier station are analyzed when fault occurs at different locations. Based on this, the identification criterion of internal and external faults is constructed by using characteristic frequency band current, and the single-end protection scheme of DC line is designed. Simulative results based on PSCAD/EMTDC indicate that the proposed protection scheme can accurately identify internal and external faults, and has good resistance to transition resistance and anti-noise-interference ability.