Control design for a voltage regulator in a single-phase grid-connected PV inverter

Abstract

This work presents the design guidelines of a control for direct regulation of the voltage amplitude at the connection point of a single-phase gridconnected PV inverter. The parameters of such control are designed for ensuring locally asymptotic stability for a given range of the impedance. Usually, the design of the controllers are done by applying the drop method approximation. This work evaluates the application of another method, that consists in a linearization of the non-linear curve relating the amplitude of the voltage at the connection point with the injected active and reactive power. It has been studied the control strategy of drop method and new control strategy, which considers the real function and its linearization. Numerical simulations for the last method confirm the expected proper voltage regulation and the control robustness with respect to the grid impedance variations without the requirement of any estimation or measure of the actual impedance. This thesis shows, through a comparison between the drop method and the linearization method, what is the more realistic one. The results show that the linearization method is faster and has more accuracy than the drop method. This is more evident when one or more control parameters change.