Metod och anordning för fellokalisering för distributionsnätverk

摘要

The present invention relates to a method for location of a fault which has occurred on one of a plurality of lines in a power distribution network where the location is performed with the said of measured values of the common supply voltage of the said plurality of lines and the currents of the said plurality of lines after the occurrence of a fault; calculating the equivalent positive-sequence impedance Zf/1k and zero-sequence impedance Zf/0k of the network in a pre-fault steady state for all M nodes based on knowledge of the configuration and topology of the network, and obtaining, via a superordinate protection system, which of said plurality of lines has become faulty and which type of fault has occurred. The invention is characterised by calculating the equivalent impedance Zek using fault loop calculation depending on the fault type as $wherekI\; =\; IpN\; DIVIDED\; 3Ip-IpN\; , Z1N\; =\; Vph\; DIVIDED\; Ip-IpN¾3\; ,,and:\; Vph\; -\; voltage\; at\; the\; faulty\; phase,\; Z1f\; -\; positive-sequence\; fault-loop\; impedance\; obtained\; from\; measurements,\; Ip,\; IpN\; -\; adequately:\; fault-loop\; and\; residual\; currents\; obtained\; from\; measurements,\; and\; checking\; if\; Im(Zek)\; \ge \; 0,\; k\; =\; 1,2,..M\; wherein,\; upon\; being\; fulfilled,\; the\; distance\; to\; fault\; is\; chosen.\mathop{\mathrm{image}}$