Abstract

The Brushless Doubly-Fed Reluctance Generator (BDFRG) is a potential alternative to the Doubly Fed Induction Generator (DFIG) in wind power applications owing to its reasonable cost, competitive performance, and high reliability. In comparison with the Brushless Doubly-Fed Induction Generator (BDFIG), the BDFRG is more efficient and easier to control owing to the cage-less rotor. One of the most preferable advantages of BDFRG over DFIG is the inherently better performance under unbalanced grid conditions. The study conducted in this paper showed that conventional vector control of the BDFRG results in excessive oscillations of the primary active/reactive power, electromagnetic torque, and primary/secondary currents in this case. In order to address such limitations, this paper presented a new control strategy for the unbalanced operation of BDFRG-based wind generation systems. A modified vector control scheme was proposed with the capability to control the positive and the negative sequences of the secondary currents independently, thus greatly reducing the adverse implications of the unbalanced supply. The controller performance has been validated by simulations using a 1.5 MW BDFRG dynamical model built upon the positive and negative sequence equations. The main benefits of the new control strategy are quantified in comparison with conventional PI current control design.

Highlights

  • The continuously growing energy demands from depleting conventional sources and the accompanying environmental concerns with harmful green-house gas emissions and high pollution impose significant challenges to overcome

  • During the past few decades, they have been rapidly developed in response to increasing requirements for a wide range of new applications such as [1]: wind energy conversion systems (WECS), micro-grids, electric vehicles, more electric aircrafts, electric ship propulsion, high-power industrial drives, robotics, etc

  • In order to minimize these limitations and enhance its market competitiveness, further performance improvements are necessary, especially through the rotor optimization [2]. This promising machine technology is still evolving and according to the latest design and control advances it should be seriously considered as a viable substitute to Doubly Fed Induction Machine (DFIM), foremost as a wind turbine generator (BDFRG) [3]

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Summary

Department

Mathematics, Physics and Electrical Engineering, Newcastle City Campus, Northumbria University at Newcastle, Newcastle-upon-Tyne NE1 8ST, UK.

Introduction
BDFRM Model under Balanced Conditions
Mathematical Model under Unbalanced Grid Voltage Condition
Power and Torque Relationships
Methods for Real-Time Separation of Positive and Negative Sequences
Conventional Vector Control
Findings
Proposed Control Strategy under Unbalanced Grid Voltage Conditions
Full Text
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