A graph search algorithm for optimal placement of fixed and switched capacitors on radial distribution systems

Proper placement of fixed and switched shunt capacitors on primary distribution feeders reduces power and energy losses, increases the available capacity of the feeders, and improves the feeder voltage profile. This paper presents a practical solution technique to the capacitor placement problem that is easy to implement. The proposed approach uses a graph search algorithm. The method has been tested along with other methods on existing feeders using actual data. Test results indicate that the proposed approach is well suited to the problem and determines a near-optimal solution. The method can handle standard capacitor sizes and associated costs, and the resulting nondifferentiable objective function, with ease. It can also determine the type of capacitors to be installed, and the switching times of the switched ones. The algorithm is currently being used for placement of shunt capacitors on distribution systems of a large electric utility.