Control of three-phase voltage source inverter for renewable energy applications

This paper introduces a fast and optimized control scheme for grid-connected voltage source inverters (VSI) used in renewable energy applications. To deliver power from a renewable energy source to the utility grid, a fast controller is required to maximize power delivery. Many grid-side control methods have been proposed in the literature, which present different approaches to this problem. The proposed method provides solutions for the drawbacks associated with conventional Pl-controller-based grid-side controllers. These drawbacks include slow dynamics, and distortion in the control feedback signal. This method uses a proportional resonant (PR) controller optimized through linear quadratic regulation (LQR) to track the reference current produced by an instantaneous power-based current reference generation method. The instantaneous power-based current reference generation method eliminates the delay inherent in average power-based current reference generation methods. The proposed control loop is fast due to the fast dynamics of the PR controller. It rejects the sinusoidal disturbance produced by the voltage at the point-of-common-coupling (PCC) due to the disturbance rejection capabilities of the PR controller at the resonant frequency. Finally, the PR controller coefficients are optimized through LQR in order for the controller to reach peak performance. Simulation results of this grid-side control method are presented, which verify its validity and feasibility.