超(特)高压输电线路高速行波差动保护

High speed traveling wave differential protection for EHV/UHV transmission line

提出了一种行波电流差动保护的新算法,首先利用形态学交替混合滤波器去除行波信号中的噪声,并提取方向电流行波波头对应的时间,然后计算从方向电流行波起始时间开始数十微秒内方向电流行波波形的积分值,将输电线路两端的同向电流行波积分值的差值作为行波电流差动保护的动作依据。当被保护线路外部短路故障时上述差值很小,而被保护线路内部短路故障时该差值很大,从而明显地区分出内部和外部故障。该算法由于只利用了行波起始部分数十微秒内的信号,其动作时间主要决定于线路两端的通信时间,因此一般动作时间只有几毫秒。分析和仿真表明该算法动作速度快、可靠性高,可以作为超(特)高压输电线路的主保护。

An algorithm of traveling wave differential protection is proposed,which applies a morphological alternating hybrid filter to remove the noise of traveling wave signal,extracts the corresponding time of the traveling wave head of directional current,calculates the integral value of directional current traveling wave for tens of milliseconds after its starting time,and takes the difference between the integral values of the same directional current at both ends of transmission line as the criterion of traveling wave current differential protection.The difference is very small when short-circuit fault occurs beyond the protected line while it is very large when internal short-circuit fault of the protected line occurs.Since the algorithm only needs tens of milliseconds,the protection action time depends on the communication speed between two ends of the line,i.e.several microseconds.Analysis and simulation show that the introduced algorithm has high speed and reliability,suitable for the primary protection of EHV/ UHV transmission line.