Stationary frame-based predictive sensorless current control with zero steady state error

This paper proposes a stationary frame-based sensorless predictive current controller with zero steady state error for inverter based distribution generation systems. Analytical expressions for the error sources in the predictive current controller are derived. The stability margin for the predictive current control gain is also presented. A digital adaptive algorithm based on the steepest descent method for the grid voltage has been embedded in the control system to eliminate steady state error. The adaptive controller gains are determined by minimizing a cost function that reduces the tracking error. The elimination of the steady state error is achieved by a better prediction of the grid voltage based on adaptive algorithm, which minimizes the cost function. The on line adaptive controller algorithm guarantees the high robustness of the proposed system. The grid voltage estimation expressions for sensorless operation are derived to enhance the system reliability and performance therefore; the number of measurement sensors is decreased. The proposed control solution provides high quality of current injected to the grid and, therefore, high power quality. Finally, simulated and practical results are included to verify the derived expressions and the performance of the proposed control system.