SIMULATION ANALYSIS OF DFIG CHARACTERISTICS UNDER d–q CONTROL STRATEGIES IN STATOR-VOLTAGE-ORIENTED FRAME

S. Li∗ and T.A. Haskew∗

Keywords

Wind power, doublyfed induction generator, AC machine d–q vector control, statorvoltage orientation frame, modeling and simulation

Abstract

The technology employed for electromechanical energy conversion in large wind turbines deviates from that used in traditional generation equipment. Induction machines, rather than synchronous generators, are used in most commercial wind turbines. The doubly-fed induction generator (DFIG) is a “special variable-speed induction machine widely utilized in modern large wind turbines. Unlike a conventional fixed-speed induction machine, a DFIG transfers power to the grid through both the stator and rotor paths, and its characteristics depend strongly on how the generator is controlled. To enhance control design and analysis, this paper investigates DFIG steady-state characteristics through computer simulation. The paper presents a steady-state model that allows (1) DFIG characteristic study under decoupled d–q control strategies in a stator-voltage-oriented frame and (2) power computation of both the stator and rotor paths. The steady-state model is validated through a transient simulation system by using SimPowerSystem. Extensive simulation-based studies are performed to investigate how DFIG characteristics are affected by different d–q control conditions in the stator-voltage-oriented frame.

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