Computation of closest bifurcations in power systems

Voltage collapse and blackout can occur in an electric power system when load powers vary so that the system loses stability in a saddle node bifurcation. This paper computes load powers at which bifurcation occurs and which are locally closest to given operating load powers. The distance in load power parameter space to this locally closest bifurcation is an index of voltage collapse and a minimum load power margin. The computations are illustrated for several power systems. Monte-Carlo optimization techniques are applied to obtain multiple minimum load power margins. The use of load power margin sensitivities to select system controls is discussed