Özet:

Unified power flow controller (UPFC) is a complex Flexible AC Transmission System (FACTS) device. UPFC is capable of controlling selectively the transmission line parameters in order to power flow control and power oscillation damping. This paper presents an advance to power flow control in a power system with UPFC by two nonlinear controllers; one based on the Control Lyapunov Function (CLF) (named also as Direct Lyapunov Method (DLM)) and the other is based on Sliding Mode Control. A state variable control scheme is implemented to challenge the problems of reference tracking, robustness against parameter uncertainty and rejecting external disturbances. Chattering phenomena and discontinuity of the controllers are also removed to obtain a continuous and smooth controller. The proposed controllers are robust against uncertainties and reject external disturbances. Simulation results are given to illustrate the effectiveness and robustness of the proposed algorithm. As the most simply measurable states of the system are used in suggested controllers, there is no need to design state space variable observer system.

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