Optimal placement of UPFC for maximizing system loadability and minimize active power losses by NSGA-II

This paper presented application of a new variant of Genetic Algorithm, specialized in multi-objective optimizations problem known as Non-dominated Sorting Genetic Algorithm II (NSGA-II), to obtain the optimal allocation of Unified Power Flow Controller (UPFC) for enhancing the power system loadability as well as minimizing the active power loss in transmission line. An Optimal Power Flow (OPF) problem with mixed integer programming has been formulated for optimizing the above two objectives as well as obtaining the optimal location of the UPFC while maintaining the system security and stability margins, e.g., small signal stability, voltage stability index, and line stability factor. In addition, a fuzzy based mechanism has been employed to extract the best compromise solution from the Pareto front. The effectiveness of the proposed methodology has been investigated on a standard IEEE 30-bus and practical Java-Bali 24-bus of Indonesian systems. Results demonstrate that the static and dynamic performances of the power system can be effectively enhanced by the optimal allocation of the UPFC. Moreover, UPFC installation cost is also calculated and overall performance has been compared with existing method.