New method for identification and localisation of an earthfault in compensated networks

Abstract

Due to today´s increased demands on grid operation management, new methods for earth fault localization and detection are needed. The fault localization should be performed as quickly as possible and under the condition, that the fault current at the fault location will not be significantly increased. In today´s meshed compensated networks with increased length, only the transient relays work correctly. But these relays give a signalization only during the beginning of an earth fault. They are not able to give correct information after a change of the network-configuration. During the steady state of the earthfault more or less all existing methods cause problems. The new proposed method is based on injection of a zero-sequence current during an earthfault by tuning the Petersen-Coil. The relays have to use a simple evaluation of the zero-sequence current in the complex plane. Using this method, an identification of the faulty feeder as well as a distance estimation up to the earthfault location is possible. This paper will present the first results of this evaluation.