Stability analysis for power swing protection

A transmission line trip during a power swing may cause instability of a power system. It is necessary to recognize the power swing from fault. Based on stability boundary, the power swing blocking relays must be set. To do that, first power swing should be analyzed. Second a way of probability of occurrence of fault must be found. Third, the critical condition under which the stability of a power system not disturbed is recognized. Finally the settings of the power swing relays are calculated. In this paper, analysis of the power swing occurrence has been made. By defining transmissions and generators sensitivities coefficients, the way of making the line under consideration full load is found. The way of minimization of distance between load impedance and the last zone of distance protection is given and the settings of the power swing relays are calculated.