Transient algorithm based on earth capacitance estimation for earth-fault detection in medium-voltage networks

This study presents a new earth-fault detection algorithm for both unearthed and compensated neutral medium-voltage networks. The proposed algorithm is based on the transient estimation of the earth capacitance of the background network during the first one-eighth of the power frequency period. The effects of feeder impedances and the Petersen coil (in compensated networks) are compensated using proposed compensation factors. The estimated capacitance accurately indicates if the feeder is faulted or not. The capacitance can be estimated with a maximum error of +/- 10 \%. The algorithm is not reliant on the fault resistance and the faulted feeder parameters; it mainly depends on the background network. The network is simulated using the ATP/EMTP program. Different fault conditions are covered in the simulation process, including different fault inception angles and high fault resistances.