Novel damping control schemes using the unified power flow controller and fuzzy theory

This paper proposes a novel UPFC damping control scheme using fuzzy controllers working on local signals. The design of controller is based on the time-domain analysis of the system transient energy function (TEF) and implemented by using fuzzy controllers to damp low frequency electromechanical power oscillations. The detailed design procedure of fuzzy based damping controllers is firstly addressed. Comprehensive computer simulations are then carried out to verify the feasibility of the proposed control scheme. The control effectiveness of using a combination of different control modes in the UPFC system with respect to different local input signals to improve the transient performance of power systems is investigated and discussed in full. The simulation results on the IEEE 9-BUS test system reconfirm that the proposed damping control scheme is practically implementable and the UPFC is the most powerful FACTS device which is able to provide flexible control functions required for the real-time power flow regulation and fast transient control of power systems.