Predictive Current Control of Three-Phase Grid-Connected Converters With Constant Switching Frequency for Wind Energy Systems

A predictive current controller with an extended-state observer (ESO) is proposed for grid integration of wind energy systems. In each sampling period, the proposed strategy calculates the converter switching time that minimizes a cost function defined as a sum of squared current errors, leading to constant switching frequency. To achieve excellent dynamic performance, the impact of sampling delay is analyzed, and detailed compensation methods are proposed. In addition, an ESO is constructed to suppress parameter variations and modeling errors, which affect the performance of the controller. The parameter tuning and the stability of the observer are analyzed. The proposed strategy not only presents rapid dynamic response due to the use of the predictive current controller but also possesses robust control performance as a result of the observation algorithm. Simulation and experimental results are given to validate the effectiveness of the proposed solution.