基于前行波波形特征的柔性直流输电线路单端行波保护

Single Terminal Traveling Wave Protection for Flexible HVDC Transmission Lines Based on Forward Wave Shape Information

柔性直流输电具有更好的新能源消纳能力,对于解决大规模新能源的消纳问题具有重要意义。而现有保护原理在雷击干扰下会发生误动,相应雷击干扰识别判据硬件要求高或理论性不强。针对该问题,提出了一种基于前行波波形特征的单端量保护原理。与区内短路故障相比,区外短路和雷击干扰行波时域特征体现为波头变缓以及波尾下降,利用通式参数分别对上述波形特征进行描述,并据此分析故障前行波的波形特征,最后提取能表征波头陡度和波尾下降的前行波波形特征实现区内故障的有效识别。仿真验证结果表明该保护方法能有快速有效的完成故障识别,且具有较强的耐受过渡电阻能力和抗雷击、噪声干扰能力。

The flexible DC transmission,as a better new energy absorption capacity,is of great significance for solving the problems in large-scale new energy consumption.However,the existing protection principles may malfunction under the lightning interference,causing the high hardware requirements or weak theoretical supportings in the corresponding lightning interference identification criteria.In response to this problem,this paper proposes a single-ended protection principle based on the waveform characteristics of the forward wave.Compared with the internal short-circuit faults,the timedomain characteristics of the external short-circuit and the lightning interference traveling wave are reflected in the slowing-down of the wave head and the falling-down of the wave tail.This article uses the general parameters to describe the above-mentioned waveform characteristics and analyzes the characteristics of the forward wave of the faults.Finally,the waveform characteristics of the forward waves that characterizes the steepness of the wave head and the drop of the wave tail are extracted to realize the effective identification of the faults in the area.The simulation verifies that the protection method may quickly and effectively complete the fault identification.It has a strong ability to withstand the transition resistance,and the lightning and noise interference.