Voltage Sensorless Control for Grid-connected Power Converters based on State Feedback and State Observer

Grid-connected power converters have been increasingly utilized to inject renewable energy into the grid. To reduce installation cost and the same time to increase system stability, this paper presents control design for grid-connected power converters with only current sensors. The proposed control scheme mainly consists of a state-feedback controller and a state observer. To guarantee the stability of the closed-loop system, linear matrix inequality approach is employed to obtain control gains. As opposed to the existing approaches, the proposed scheme offers superior dynamic performance under voltage sag. Such improvement is achieved by incorporating the internal model of proportional controller into the state-feedback controller. The effectiveness of the proposed controller is validated by simulations under various operating conditions.