Bifurcation of frequency perturbations analysis due to faults and power swings

The paper presents the result of faults and power swings transient measurements occurred at 400 kV Switching Station Girawali, Maharashtra State, India. It is having lines fed from Parali Thermal Power station, Super Thermal Power Station; Chandrapur, Solapur, Lonikand and indirectly connected to Koyna hydro power station. The oscillographs of phase currents and voltages with neutral parameters are measured online during transient processes of line faults and power swings to compare them with respect to the frequency perturbations. Computer simulation is performed to analyze frequency from point to point. The fluctuations and perturbations in frequency during fault stage and rotor dynamics stage are measured. An algorithm is developed to activate and block the power swing detection by measuring frequency changes. The occurrences of frequency fluctuations and perturbations are high in case of power swings as compared to faults. Logic is developed to utilize this feature for bifurcation