Optimal coordinated design of UPFC and PSS for improving power system performance by using multi-objective water cycle algorithm

•A new optimization algorithm is used for UPFC and PSS placement.•The proposed algorithm also determines the parameters of controllers coordinately.•A mixed integer nonlinear problem is obtained for the design procedure.•The best Pareto optimal set is also attained by defining this problem as a multi-objective function.•The analytical analysis and simulations confirm the advantages of this method.

This paper presents an optimal design for simultaneously locating unified power flow controller (UPFC) and power system stabilizer (PSS). The parameters of their controllers are also tuned coordinately to enhance the power system stability. A mixed integer nonlinear problem is obtained for the design procedure due to the characteristics of selected objective functions. A new population-based meta-heuristic algorithm, called water cycle algorithm (WCA) is used to solve this problem. The best Pareto optimal set is also attained by defining this problem as a multi-objective function. The simulations results on IEEE 39-bus power system confirm the efficiency and the superior performance of the proposed method when compared with other algorithms.