Multiple-vectors-based model predictive direct power control of doubly fed induction generator under unbalanced grid voltage condition

Abstract

Model predictive direct power control (MPDPC) has been widely noticed in the field of doubly fed induction generator (DFIG) control. The optimal vector is selected based on the principle of power error minimization. However, conventional MPDPC will produce high power ripples and large current distortion under unbalanced grid voltage condition. To achieve sinusoidal stator currents and/or constant powers, both positive and negative sequence extraction of stator voltage and/or currents are required to calculate the power or current compensation value. The calculation is really complicated. To cope with the problems above, this paper proposes an improved MPDPC using a new defined instantaneous reactive power. Furthermore, there will be two vectors (including one active-vector and one zero-vector) applied during the coming control period to achieve better steady-stage performance. In this way, the sinusoidal but unbalanced stator currents are obtained without complicated calculation of power or current compensation and positive/negative sequence extraction of stator voltage and/or currents. Simulation results for conventional and proposed MPDPC are presented and compared with each other to validate the effectiveness of the proposed method.