Comparison between optimal control strategies applied to a system with unified power flow controller, shunt converter and series converter

Recent advances in the power system handling capabilities of static switches have made the use of the voltage source inverter (VSI) feasible at both transmission and distribution levels. This paper is focused on comparison between optimal control strategies applied to a system with unified power flow controller, shunt converter and series converter. The control strategies were tested using a power system distribution model. The presented results show that when the system is with one converter, there will be only two control inputs in the system, making it possible to track only two outputs in the system. If the objective is to maintain capacitor voltage constant, it is possible to track one output of the system for the capacitor voltage to be maintained constant. When the system is with two converters, then there will be four control inputs in system, and so it is possible to track four outputs in the system. The series converter can eliminate the voltage flicker that exists in the same branch the series converter is located in, while the shunt converter can eliminate the current harmonics. The UPFC can remove both the current harmonics and voltage flicker from the system.