Direct Flux Control for Stand-Alone Operation

In this paper, a novel voltage control strategy of stand-alone operation brushless doubly 9 fed induction generator for variable speed constant frequency wind energy conversion systems 10 was presented and discussed particularly. Based on the model of the generator power system, the 11 proposed direct flux control strategy employs a nonlinear reduced-order generalized integrator 12 based resonant sliding-mode control scheme to directly calculate and regulated the output value of 13 converter which control winding stator required so as to eliminate the instantaneous errors of 14 power winding stator flux, and no involving any synchronous rotating coordinate transformations. 15 The stability, robustness and convergence capability of the proposed control strategy were 16 described and analyzed. Owing to no extra current control loops involved, therefore simplifying 17 the system configuration design and enhancing the transient performance. Constant converter 18 switching frequency was achieved by using space vector pulse width modulation, which reduce 19 the harmonic of generator terminal voltage. In addition, experimental results prove the feasibility 20 and validity of the proposed scheme, and excellent steady and dynamic state performance is 21 achieved. 22