Search

This article proposes an improved vector control scheme based on the magnetizing current for the dual-stator brushless doubly fed induction generator during the standalone operation. The conventional scheme of the standalone control chooses the control winding current as the control object for the inner current loop, suffering from the large variation of the output voltage caused by the large output impedance. The improved scheme of this article selects the power winding magnetizing current as the control object, which can reduce the demagnetizing influence of the load current. Meanwhile, the design of the outer voltage loop can be simplified because of the direct relationship between the output voltage and the power winding magnetizing current. The main aim of this article is to design an improved standalone controller to enhance the transient performance of the system. A prototype of the dual-stator brushless doubly fed induction generator, which employs the proposed scheme, is measured for validation. [ABSTRACT FROM AUTHOR]

This paper presents a finite-set model predictive power control (FS-MPPC) method for the brushless doubly fed twin stator induction generator (BDFTSIG) in variable speed constant frequency generation applications. The FS-MPPC controller is developed in a general reference frame from which all other reference frames can be deduced readily. The invariant feature of the predictive power model in various reference frames contributes to the reference frame-free characteristic of the developed FS-MPPC controller, enabling its application more flexible and universal. Besides, the arduous process of control winding flux estimation is avoided in the FS-MPPC controller by choosing state variables that are easy to be obtained. Moreover, the influence of rotor circuit that has long been neglected in the existing controllers for the brushless doubly fed induction machines is embedded within the predictive power model and inherently considered in the FS-MPPC controller, which contributes to accurate power control of the BDFTSIG. Furthermore, the feasibility and effectiveness of the developed FS-MPPC controller regarding different power levels and grid fault conditions are briefly discussed. Finally, numerical simulations and experimental tests are carried out, which demonstrates the effectiveness of the developed FS-MPPC controller. [ABSTRACT FROM AUTHOR]

Brushless doubly fed induction machine (BDFIM) with apparent cost advantage and high potential in reliability is regarded as a viable alternative to the commonly applied doubly fed induction machine in modern energy conversion systems. Design and analysis of the current controller, which are key points for effective control of BDFIM, are for the first time intensively studied in this paper. The complete model of control winding current loop is developed in form of complex transfer function, and its differences from the conventional simplified model are clearly revealed. An improved feedforward current control method is proposed based on the complete model, offering simple and compact control structure with only few parameters involved. Stability and transient performance analysis is carried out on both conventional and improved current controllers, which theoretically proves stability improvement and faster dynamic performance of the improved current controller. The effectiveness and superiority of the proposed current controller, as well as the consistence between theoretical analysis and actual performance, are validated by experimental results performed on a prototype BDFIM system. [ABSTRACT FROM AUTHOR]

This paper presents a dual-stator brushless doubly fed induction generator-based stand-alone wind energy conversion system (DSBDFIG-SA-WECS). With the advantages of compact structure, high reliability, and low cost, the DSBDFIG-SA-WECS shows great potential in wind energy applications. Based on the traditional stator-flux-oriented control (SFOC), an improved direct voltage control (DVC) is proposed for stand-alone operation. Performance analysis is carried out to evaluate SFOC and DVC in the aspects of control objects, orientation, feedback, and parameters involved. The DVC method is simple, robust, and cost-effective with the outer stator current sensors eliminated, and there are no extra parameters involved that the control performance can be enhanced. Fair comparisons are made in simulation to demonstrate better performance of the proposed DVC, and the effectiveness of DVC is further validated by experiment under variable speed condition. [ABSTRACT FROM PUBLISHER]

A detailed spiral vector model of the dual-stator brushless doubly fed induction machine is developed, which unifies the steady-state and dynamic analysis into a single-phase basis through introducing complex exponential variables. The modeling method is generalized to well apply to any ac machine with arbitrary winding layout. To validate the effectiveness of the proposed spiral vector model, steady-state characteristics are predicted based on the proposed model and experimentally demonstrated under all possible operation modes, namely, simple induction, cascaded induction, doubly fed synchronous, and double-cascaded induction. The dynamic performance under open-loop operation and closed-loop control is simulated, which is followed by experimental verifications. [ABSTRACT FROM AUTHOR]