Browsing by Author "Joos, G."

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    Design of a Robust Speed and Position Sensorless Decoupled P-Q Controlled Doubly-Fed Induction Generator for Variable- Speed Wind Energy Applications
    (IEEE, 2007-10) Gogas, K.; Joos, G.; Ooi, B. T.; Mwinyiwiwa, Bakari M. M.; Zhang, Y.
    This paper proposes an implementation of a decoupled P-Q control of a DFIG that does not rely on mechanical sensors and a speed and position sensorless algorithm that is robust to variations of the values of the machine parameters. In this paper, the sensorless control is based on a modified phase-locked loop with an improved positioning algorithm. This eliminates the need to estimate the speed based on the machine parameters, which results in a significant improvement in speed control robustness to parameter variations. In addition, the algorithm avoids using differentiation which can lead to significant inaccuracy due to the noise inherent in measured signals. Theoretical and simulation results were validated on an experimental setup, using a laboratory 5 hp DFIG.
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    Multi- Terminal UPFC for Power System Deregulation
    (IEEE, 2000-01) Mwinyiwiwa, Bakari M. M.; Lu, B.; Ooi, B. T.; Galiana, F. D.; McGillis, D.; Marceau, R.; Joos, G.
    One original purpose of FACTS controllers is to increase the transmission capacity of existing lines thus deferring the necessity of building new lines. FACTS, such as the unified power flow controller (UPFC), have also been regarded as controllers for routing power in the market-driven, deregulated power systems. Hitherto, the UPFC has been conceived to control the complex powers through a radial line. This paper presents the concept of a multi-terminal UPFC (M-UPFC), which serves to control the complex powers of several transmission lines converging towards (or radiating from) a transmission node. In order to show that a M-UPFC can be built, that it has stable operation and that it has all the control degrees of freedom of UPFCs, a laboratory model based on 3 units of 3-phase, voltage-source converters has been assembled and tested
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    Operating Limits of the Current Regulated Delta Modulated Current Source PWM Rectifier
    (IEEE Transactions on Industrial Electronics, 1991) Ooi, B. T.; Mwinyiwiwa, Bakari M. M.; Wang, X.; Joos, G.
    A stand alone, three-phase, delta-modulated, current-source PWM rectifier has been built and has been shown to be capable of operating with near sinusoidal current waveforms, unity power factor. and good DC current regulation. A mathematical model that has been justified against experimental measurements and results from digital simulations is presented. The current waveform distortion limit and the asymptotic stability limit are established. It is shown that the rectifier can operate safely within these limits in the entire range of its power ratings