IMPROVED CONTROL SCHEME OF DFIG WIND TURBINE SYSTEMS UNDER UNBALANCED GRID VOLTAGE

Tóm tắt

This paper proposes an enhanced nonlinear control technique based on a combination of feedback linearization (FBL) and resonant regulator as tracking controllers for the doubly-fed induction generator (DFIG) wind turbine system under unbalanced grid voltage. A nonlinear model of DFIG wind turbine system with the rotor-side converter (RSC) is firstly linearized, not by small signal analysis. Then, the proportional integral plus resonant (PI+R) regulators are utilized for tracking controller. With the combination of FBL technique and the tracking controllers based on resonant regulator, the oscillations of the power and generator torque can be much reduced in the transient and steady states. The effectiveness of the proposed scheme is verified by the simulation results for the 2 MW-DFIG wind turbine system under unbalanced grid voltage conditions.

Keywords: Current control, doubly-fed induction generator, feedback linearization theory, unbalanced grid voltage, wind turbine.