A new distance protection scheme which can operate during fast power swings

The combined effects of a high impedance ground fault condition and a fast power swing condition cause the apparent impedance 'seen' by distance protection schemes to vary over a wide range. Previous research work has shown that detection and 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 also incorporates a scheme for one pole open fault detection. This method forms a part of a complete power swing relaying scheme and can be implemented on standard relaying hardware. Simulation results are presented for a typical 400 kV power system, using the Electromagnetic Transient Program (EMTP).