Interior/exterior point methods with inertia correction for the solution of the reactive optimal power flow problem with discrete variables

Interior and Exterior Points Methods have been used for solving the Optimal Reactive Power Flow (ORPF) problem. However, the solution of the the ORPF problem is hampered when transformers tap ratios and the shunts of capacitor banks and reactors are represented by discrete variables. This work investigates the ORPF solution with the representation of the discrete variables. The proposed solution approach treats such discrete variables by means of a sinusoidal penalty function and the penalized problem is solved by the method of interior/exterior points. Due to problems caused by the insertion of the penalty function, an inertia correction strategy is proposed to correct such problems and also to assure convergence to local optima for the penalized problem. Simulations are performed on IEEE 14- and 30-bus test systems by an implementation performed in Matlab. Results presented show the efficiency of the penalty function for handling the discrete variables of the ORPF problem. Results also highlight the need for using inertia correction strategy to assure that only local minima are obtained