Optimal placement and sizing of multiple APLCs using a modified discrete PSO

In this paper, a new method is proposed to optimize the placement and size of multiple Active Power Line Conditioners (APLCs). The objective is to minimize the investment cost, while the voltage total harmonic distortion and the individual harmonic distortion as constraints are maintained within the standard level. Since the APLC size is a discrete value, the objective function has a number of local minima. To deal appropriately with this, a Modified Discrete Particle Swarm Optimization (MDPSO) has been proposed. In this optimization method, DPSO has been developed by Genetic Algorithm (GA) operators in order to increase the diversity of the optimizing variables and decrease the risk of trapping in local minima. To evaluate the proposed method, two cases are studied. In case 1, the robustness and accuracy of the MDPSO are compared with other methods, DPSO, GA, Simulated Annealing (SA), and Discrete Nonlinear Programming (DNLP). The IEEE 14-bus distribution system is modified and used in this case. In case 2, a comparison is performed between the results obtained when the APLC cost function is assumed to be proportional with its rating, as done in almost all previously published papers, and when a more realistic APLC cost is considered. For this case, the IEEE 18-bus distribution system is employed as the test system. It is illustrated that the proposed method is more accurate and robust than other methods. This is also highlighted that the lowest cost planning is achieved when the realistic APLC cost function is used. (C) 2012 Elsevier Ltd. All rights reserved.