Computation of a practical method to restore power flow solvability

As power systems become more heavily loaded, system operation will be increasingly constrained by contingent cases where the power flow equations have no real solutions. Since such cases often represent the most severe threat to system operation, it is critical that a computationally efficient method be developed to provide optimal control recommendations to mitigate these cases. Such an algorithm is developed in this paper. The degree of unsolvability is quantified using the distance in parameter space between the desired operating point and the closest solvable point. The sensitivity of this measure to different system controls is then calculated. These sensitivities are used to determine the best way to mitigate the contingency. The dynamic consequences of loss of solution are also discussed. The method is demonstrated on a small system and the IEEE 118 bus case.