LMI-Based Optimal Linear Quadratic Controller Design for Multiple Solar PV Units Connected to Distribution Networks

In this paper, a state feedback linear quadratic regulator (LQR) controller is designed for multiple PV units which are connected to distribution networks in a networked structure instead of the point of common coupling (PCC). The proposed control scheme is designed for voltage source converters (VSCs) used with different PV units to couple with existing distribution networks. The control inputs are derived using appropriate feedback gains where an linear matrix inequality (LMI)-based LQR scheme is applied to determine these gains in such a way that tracking errors for all states are minimized. The performance of the proposed scheme is evaluated through rigorous simulations under different operating conditions and compared with a conventional proportional integral (PI) controller in terms of the capability to deliver power and minimize total harmonic distortions (THDs) in the inverter output current.