Predictive Current Control of Doubly Fed Induction Generators

This paper presents a predictive current control (PCC) strategy for doubly fed induction generators (DFIGs). The method predicts the DFIG´s rotor current variations in the synchronous reference frame fixed to the stator flux within a fixed sampling period. This is then used to directly calculate the required rotor voltage to eliminate the current errors at the end of the following sampling period. Space vector modulation is used to generate the required switching pulses within the fixed sampling period. The impact of sampling delay on the accuracy of the sampled rotor current is analyzed and detailed compensation methods are proposed to improve the current control accuracy and system stability. Experimental results for a 1.5-kW DFIG system illustrate the effectiveness and robustness of the proposed control strategy during rotor current steps and rotating speed variation. Tests during negative-sequence current injection further demonstrate the excellent dynamic performance of the proposed PCC method.