Towards a more reliable operation of compensated networks in case of single phase to ground faults

The first part of this paper contains a short review on problems related to distribution system operators´ (DSOs) current practice regarding earth fault location and sustained faulty operation of compensated networks. A new device and method are then presented that have been implemented recently at Hungarian DSOs. This technique uses current injection parallel to the Petersen coil for fault location, and the same device is further used to decrease the harmonics in the residual fault current during sustained earth-fault operation. First field test results are presented. It is also shown that the CTs installed along with the proposed device1eliminate the need for the additional resistor that was necessary to select the faulted feeder.