一种高压直流输电系统接地极线路保护新方法

Novel method for HVDC power transmission system grounding electrode line protection

针对目前基于信号注入的接地极线路保护方法在某些故障情况下可能出现保护拒动的问题,提出一种基于频带电压幅值积分的接地极线路保护新方法。通过仿真分析发现在高压直流输电系统接地极线路故障后其首端电压频谱会出现明显变化,基于此提出一种利用小波包分析获取接地极线路首端电压不同频带分量,以频带电压幅值积分在一段时间内的变化为保护判据的接地极线路保护方法。基于PSCAD/EMTDC软件的大量仿真结果表明,该方法能有效检测到接地极线路上的各种故障,识别准确性不受过渡电阻的影响,具有良好的应用前景。

To deal with the problem that the existing grounding electrode line protections based on signal injection might have protection failure under certain fault conditions, a novel approach of grounding electrode line protection based on multi-band voltage amplitude integration is proposed. Simulative analysis indicates that the voltage spectrum of the head end changes greatly after the faults occurred in grounding electrode line. On this basis, the proposed approach utilizes the wavelet packet analysis to provide different frequency bands of head-end voltages, and the variation of voltage amplitude integration is used as fault identification criterion. Simulative results based on PSCAD/EMTDC indicate that the proposed protection method effectively identifies different types of faults on the grounding electrode line, and its performance is not affected by the fault resistance. Hence, the proposed approach has promising prospects for engineering applications.