针对雷击输电线路产生的暂态信号对行波保护的干扰,提出了一种雷击干扰与短路故障的积分识别方法。在详细分析雷击线路未造成故障、雷击造成故障和短路故障的暂态波形特征的基础上,构建综合识别判据。利用线路扰动后较短的时间内非故障雷击的波形对称性和故障时的波形单调性,分别对时间轴上方和下方的暂态电流波形进行积分运算。其一,根据二者的相对比值大小构成识别故障与非故障性雷击的主判据;其二,利用两个积分值的差构建辅助判据,以提高故障性雷击和非故障性雷击识别的可靠性。EMTDC仿真结果验证了所提积分识别判据的有效性和正确性。
Aiming at the impact of transient signals generated by lightning stroke on the travelling wave based protection, a novel identification algorithm is proposed. On the basis of analysis of transient current waveforms generated by fault and lightning stroke respectively, this paper presents a hybrid discrimination criterion. Using the characteristics of symmetric current waveform induced by lightning stroke without causing fault and that of asymmetric current waveform generated by general fault within a very short interval, the waveforms of transient current above and below time-axes are integrated, respectively. Firstly, through comparing their relative ratio value, the primary criterion identifying fault and lightning stroke is established. Secondly, to improve the reliability of discrimination between lightning stroke with and without causing fault, according to the difference of them, the secondary criterion is also defined. The EMTDC simulation results demonstrate that the proposed integral criterions are valid and correct.