Improvement of dynamic performance of doubly fed induction generator-based wind turbine power system under an unbalanced grid voltage condition

With the current increase in wind power penetration into the energy market, control and operation of wind turbine generators becomes a major research topic. Wind turbine based on doubly fed induction generator (DFIG), which is sensitive to grid disturbances, is widely used. Under an unbalanced grid voltage condition, oscillations of the DFIG´s electromagnetic torque and instantaneous stator powers strongly affect the dynamic performance of the DFIG. In this study, a new configuration based on vector proportional´integral (VPI) controller is proposed to eliminate such oscillations. This new configuration is employed in the rotor side converter (RSC) of the DFIG. With the proposed VPI control strategy, decomposition of sequential components and mathematical complexity are reduced. Compared with the conventional field-oriented control based on the standard single PI controller, the VPI controller can successfully eliminate torque and stator power oscillations. The effectiveness of the proposed control strategy is validated through simulation results obtained on a 1.5´MW DFIG-based wind turbine system model built in MATLAB/Simulink.