Direct Power Control of a Doudly Fed Induction Generator with a Fixed Switching Frequency

This paper presents the implementation of a direct active and reactive power control of a doubly fed induction generator (DFIG) applied to a wind generation system as an alternative to the classical field oriented control (FOC). The FOC is known to have complex control structure, which consists of current controller, power controller and frame transformations, and also depend highly on parameter variation such as rotor and stator resistances and inductances. The proposed direct power control (DPC) method produces a fast and robust power response without calling for complex structure and algorithms. However, it has high power ripple during steady state. In this paper, active and reactive power controllers and space-vector modulation (SVM) are combined to replace the hysteresis controllers used in the original DPC drive, resulting in the fixed switching frequency of power converter. The simulation results with FOC and DPC for a 3 kW DFIG are given and discussed and experimental results for the same machine are shown to illustrate the feasibility of the proposed control strategy.