PROTECTIVE RELAY SYSTEM WITH SPACIAL DIFFERENCE FILTER AND SUMMING FILTER

摘要

A protective relay system for discriminating whether or not fault point of the power system exists within a predetermined range, which comprises an addition filter adapted to input sampling data vm, im of voltage v, current i of the power system to a filter having transfer function (1+Z-1+Z-2+ ··· +Z-n) (1+Z-1) (Z is Z transform operator to obtain voltage data vsm, current data ism as output, a difference filter adapted to input sampling data vm, im of the voltage v, current i to a filter having transfer function (Z-k-Z-q) (k+q=n+1; k q) to obtain voltage data vjm, current data ijm as output, a controlled variable calculation unit for calculating reactance value Xm on the basis of the following equation:Xm = -vsm·ism-p+ism·vsm-p-ijm·ism-p+ijm-p·ism from voltage vsm, current ism obtained at the addition filter and voltage vjm, current ijm obtained at the difference filter at time tm and voltage vsm-p, current ism-p obtained from the addition filter and voltage vjm-p, current ijm-p obtained from the difference filter at time tm-p, and an operation judgment unit for judging whether or not Xm ≦ Xs holds, from reactance value Xm and setting value Xs obtained at the controlled variable calculation means.