Multivariable discrete time sliding mode control based UPFC for power flow tracking over an UHV interconnection

This paper presents a Multivariable Discrete Time Sliding Mode Control (MDTSMC) based controller for a UPFC (unified power flow controller) to achieve rapid power flow reference tracking over an UHV interconnection between two stable power systems. The proposed controller, based on UPFC's discrete state dynamics and discrete sliding mode technique, overcomes the drawback of conventional linear continuous controllers, which are typically tuned for one specific operating condition and lacks robustness and transient accuracy. First, based on Kirchhoff's equations and (d-q) transformation, a dynamic model of UPFC is establish in state space then, the MDTSMC controller for the UPFC is designed based on the plant dynamics. The proposed control, when applied to drive the UHV interconnection, is validated via detailed simulation results which show that the proposed controller recover robustness, effectiveness and accuracy proprieties.