A Complementary SVC-Based Controller Design for Damping Both Local and Inter-Area Oscillating Modes Using NSGA-II Algorithm

Static Var compensator (SVC) is one of flexible AC transmission system (FACTS) elements mainly used for reactive power and voltage control in power systems. This paper deals with multi-modal electromechanical oscillations damping in the presence of severe disturbances. These oscillations include local modes, inter-area modes and inter-plant modes. To enhance the damping of the oscillations, the complementary controller is added to voltage regulator of SVC. In order to design such a controller, as a significant contribution of this paper, either of oscillating modes is considered as a distinct objective function and a multi-objective optimization model is employed to improve all these oscillating modes simultaneously. Accordingly, in this paper, the non-dominated sorting genetic algorithm-II (NSGA-II) approach is used to optimize all the parameters of complementary controller with the aim of minimizing all three objective functions. By applying NSGA-II method 10 non-dominated solutions are generated, and a fuzzy method is utilized to select the best compromise solution among the produced solutions. The well-tuned complementary SVC-based controller is examined on a two area power system and results obtained through simulating different cases illustrate the robustness and the efficiency of the proposed controller.