A fast nonlinear control technique for a grid-connected voltage source inverter with LCL filter used in renewable energy power conditioning systems

This paper presents a new controller scheme for a grid-connected voltage source inverter with an LCL filter based on the Control Lyapunov Function (CLF). Conventional Proportional Resonant (PR) controllers are not able to provide a fast transient response due to their limited bandwidth. Therefore, they have difficulties handling severe load transients. Additionally, they can only reject the disturbance created by the grid voltage to some extent. The proposed CLF-based controller is able to increase the bandwidth of the closed loop control system, while providing guaranteed stability and perfect disturbance rejection. Since the proposed controller is based on the system model, it is able to completely remove the disturbances caused by the grid voltage. The integral terms of the error are also incorporated into the Lyapunov function in order to account for parameter uncertainties in the system model. The performance of the proposed control scheme has been compared to the PR controller through experimental results. The experimental results demonstrate the superior performance of the proposed control scheme over the conventional PR controller.