Voltage Sensorless Control Scheme Based on Extended-State Estimator for a Grid-Connected Inverter

This article presents a robust voltage sensorless control scheme to eliminate the need of line-voltage sensors in an LCL-filtered grid-connected inverter system. The proposed control scheme is based on an extended-state estimator structure which consists of a state feedback regulator and an estimator. The main contribution of this article relies on the utilization of the linear matrix inequality approach and the internal model principle to synthesis a robust control scheme that equips a grid-connected inverter with the ability to withstand grid disturbances. As opposed to the existing works, the proposed control scheme can simultaneously deal with all types of grid disturbances, such as grid voltage distortion, grid voltage imbalance, and grid impedance variations. The effectiveness of the proposed controller is highlighted through comparative simulation results and in-depth analyses. Experimental results are also given to validate the practicality of the proposed control scheme.