A new principle for high resistance earth fault detection during fast power swings for distance protection

The combined effects of a high impedance ground fault condit~on and a fast power swing condition cause the a p p a r ~ ~~mt pedance‘ seen’ by distance protection schemes to vary over a wide range. Previous research work has shown that d@tectioa~n d location of high impedance faults during power swings is very difficult. A new principle for high impedance fault detection during fast power swings is presented which overcome these deficiencies. This method forms a part of a c om~ l e ~poew er swing relaying scheme and can be implemented on sta~dard relaying hardware. Results are presented based on extensive simul~t~osntu dies carried out on a typical 400 kV e Electro~agnet~Tcr ansient program (EMTP).