基于Hilbert-Huang变换的HVDC突变量方向纵联保护方法

摘要

高压直流输电线路的行波保护存在对装置采样率要求高及耐受过渡电阻能力差等问题.作为后备保护的纵联电流差动保护,为了防止线路分布电容等问题导致的误动,失去了速动性的优点,动作时间较长.利用HVDC线路发生区内外故障时,两端保护装置检测的电压和电流突变量的极性差异,提出基于Hilbert-Huang变换的突变量方向纵联保护方法.在分析不同故障时电压和电流突变量相位差别的基础上,采用Hilbert-Huang变换求取突变量相位差,识别两者的极性差异,进而判断故障发生的方向.基于PSCAD/EMTDC搭建了高压直流输电仿真模型,仿真结果表明,所提方法在各种故障情况下都能够实现保护的快速识别,可靠性高,且受过渡电阻的影响较小.%The traveling wave protection of HVDC transmission line is easily affected by fault resistance and requires high sampling rate of the device.While in order to prevent misuse caused by the line distributed capacitance,operation speed of the current differential protection which serves as a back-up protection is usually slow,losing the characteristic of fast speed.By the difference of the polarities of the fault components of voltage and current detected,this paper proposes a directional pilot protection method of fault component for HVDC transmission lines based on Hilbert-Huang transform.On the basis of analyzing the difference of the polarities of the fault components of voltage and current for different faults,the polarities of the fault components can be calculated by Hilbert-Huang transform to distinguish different fault directions.Based on PSCAD/EMTDC,a simulation model is built and the simulation results show that the proposed method can effectively identify the various faults with high speed,sensitivity and reliability and is less affected by the transition resistance.