Design of sliding mode controller for UPFC to improve power oscillation damping

In this paper, a new indirect method of sliding mode control (SMC) for series converter of unified power flow controller (UPFC) is proposed. In this method, the dynamic model of controller is obtained through special concepts of state variable transform, feedback linearization and differentially flat output. This new and simple control strategy has been developed base on the modified SMC principles which utilizes only the active and reactive output powers as the control inputs. Since these measurable control inputs are known as differentially flat outputs, they have a direct influence on the state variables of series converter to control them with the capability of power oscillation damping. The absence of discontinuous component input to UPFC controller avoids the chattering effect on state variables, especially on the dc capacitor voltage of inverters. For the validation of the proposed new controller, the obtained results were compared with results obtained from the PI controller.

► In this paper, a new indirect method of sliding mode control (SMC) for series converter of unified power flow controller (UPFC) is proposed.
► In this method, the dynamic model of controller is obtained through special concepts of state variable transform, feedback linearization and differentially flat output.
► This new and simple control strategy has been developed base on the modified SMC principles which utilizes only the active and reactive output powers as the control inputs.
► The absence of discontinuous component input to UPFC controller avoids the chattering effect on state variables.
► For validation of the proposed new controller, the obtained results were compared with results obtained from the PI controller.