Management of reactive power resources is essential for the secure and stable functioning of power systems in the standpoint of voltage stability. The principal aim of optimal reactive power dispatch (ORPD) is to detect the settings of control variables such as the voltage rating of generators, reactive power injection of VAR compensators and tap ratios of the tap setting transformers in order to decrease the grid congestion with one or more objective of minimizing the active power loss for a fixed economic power schedule while meeting a given lot of constraints. In this paper, Flexible AC Transmission System (FACTS) controllers named as Unified Power Flow Controller (UPFC) is added with conventional ORPD problem for active power loss minimization with voltage profile improvement. Also, this paper demonstrates the application of sine cosine algorithm (SCA) to discover the optimal solution of ORPD (with UPFC) of power system with different test systems with distinct cases such as minimization of active power losses and improvement of voltage profile. Simulation results show the high quality and accuracy of the proposed algorithm, and considering the quality of the solution obtained, the proposed algorithm appears to be efficient and robust to solve the ORPD problem comparing with existing literatures.

The major purpose of optimal reactive power dispatch (ORPD) is to detect control variables like the voltage ratings of the generator, switchable shunt condenser banks, and the tap ratio of the tap setting transformer to reduce the active power loss for fixed economic power planning when taking on a set of constraints. This paper introduces the application of the sine cosine algorithm (SCA) to find the novel solution for the reactive power dispatch of power systems with different test systems (Standard IEEE 14-bus, IEEE 57-bus and IEEE 118- bus) with specific cases like reducing active power losses and increasing bus voltages in test systems. Obtained results validate the high tone of the proposed algorithm, with better, fast and consistent results comparing with existing literatures.