Abstract
In this paper, a novel voltage control strategy for stand-alone operation brushless doubly fed induction generators for variable speed constant frequency wind energy conversion systems was presented and discussed. Based on the model of the power generation system, the proposed direct flux control strategy employs a nonlinear reduced-order generalized integrator-based resonant sliding-mode control approach to directly calculate and regulate the output value of converter which the control winding stator requires so as to eliminate its instantaneous errors, without involving any synchronous rotating coordinate transformations. The stability, robustness and convergence capability of the proposed control strategy were described and analyzed. Owing to the fact no additional current control inner loops are involved, the system configuration is therefore simplified and the dynamic performance enhanced. A constant converter switching frequency was achieved by using space vector pulse width modulation, which reduces the harmonics of the generator terminal voltage. In addition, the feasibility and validity of the proposed scheme is verified by experiments, and excellent steady and transient performance is achieved.
Highlights
Among variable-speed constant-frequency (VSCF) wind energy conversion systems (WECS), a brushless doubly-fed induction generator (BDFIG) is a reliable option that inherits the doubly-fed induction generator (DFIG)’s benefits of low cost structure due to the facts that no permanent magnets materials are utilized and only a fractionally rated converter is needed
In order to tackle the disadvantages highlighted earlier, this paper presents a novel direct flux control (DFC) scheme for stand-alone operation BDFIG using a resonant(R)-based SMC approach
It directly regulate power winding (PW) stator flux by calculating and adjusting the control winding (CW) stator voltage, rather than extra CW stator current control loops involved in vector control (VC), it employed a reduced order generalized integrator (ROGI)-based resonant nonlinear SMC to eliminate the sinusoidal tracking error, whereas, the VC algorithm using PI controller linear regulates with decoupling work
Summary
Among variable-speed constant-frequency (VSCF) wind energy conversion systems (WECS), a brushless doubly-fed induction generator (BDFIG) is a reliable option that inherits the doubly-fed induction generator (DFIG)’s benefits of low cost structure due to the facts that no permanent magnets materials are utilized and only a fractionally rated converter is needed. The sliding-mode (SM) control (SMC) strategy is an effective scheme for nonlinear systems with uncertainties It features simple implementation, disturbance rejection, strong robustness, and sensitive responses. In order to tackle the disadvantages highlighted earlier, this paper presents a novel direct flux control (DFC) scheme for stand-alone operation BDFIG using a resonant(R)-based SMC approach. It regulates the instantaneous PW stator flux without extra CW current control or involving rotating coordinate transformations. The required CW stator voltage can be directly procured in the PW stator stationary reference frame and a nonlinear reduced order generalized integrator (ROGI)-based sliding surface is introduced.
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