兼顾短路与断线故障识别的柔性直流电网行波保护方案

A traveling wave protection scheme for flexible DC power grids considering both short-circuit and breakage fault identification

目前大多数柔性直流电网行波保护在配置时仅考虑短路故障,当发生断线故障时,保护动作的正确性尚不明确。对此,首先分析了断线故障下传统行波保护的动作特性,得出了传统行波保护无法正确识别短路与断线故障的结论。在此基础上,探索了断线与短路故障下线路受端的第二个电流波头特征和线路电压特征,研究了两种故障下线路送端的电流首行波特征以及两端电压与电流变化量乘积的特征,提出了一种兼顾短路与断线故障识别的行波保护方案。基于PSCAD/EMTDC仿真平台对所提保护方案进行了性能验证。结果表明,该保护方案能准确识别并应对各种条件的故障,且具有较高的速动性和抗噪声干扰能力。

Currently,most traveling wave protection of flexible DC power grids only considers short-circuit faults when configured.When breakage faults occur,the correctness of protection actions is unclear.In response to this problem,the action characteristics of traditional traveling wave protection under breakage faults are first analyzed.It is concluded that traditional traveling wave protection cannot correctly identify short-circuit and breakage faults.Thus,the second current traveling wave front characteristics and line voltage characteristics at the receiving end of the line under breakage and short-circuit faults are explored.The first current traveling wave characteristics at the sending end of the line and the characteristics of the product of voltage and current changes at both ends under the two kinds of faults are studied.A traveling wave protection scheme considering both short-circuit and breakage fault identification is proposed.The performance of the proposed protection scheme is verified on the PSCAD/EMTDC simulation platform.The results show that the protection scheme can accurately recognize and cope with faults of various conditions and has high speed and resistance to noise interference.This work is supported by the National Natural Science Foundation of China(No.52207107).