Optimal reactive/voltage control by an improved harmony search algorithm

This paper presents an improved harmony search algorithm for the optimal reactive/voltage control problem. Optimal reactive/voltage control is a mixed integer, nonlinear optimization problem which includes both continuous and discrete control variables. The proposed algorithm is used to find the settings of control variables such as generator voltages, tap positions of tap changing transformers and the amount of reactive compensation devices to optimize a certain objective. The objectives are power transmission loss, voltage stability and voltage profile which are optimized separately. In the presented method, the inequality constraints are handled by penalty coefficients. The study is implemented on the IEEE 30 Bus system and the results are compared with other evolutionary programs such as harmony search algorithm (HSA) and particle swarm optimization (PSO).