Browsing by Author "Dumakude, Niniva"
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- ItemWind Turbine and slip permanent magnet coupler design analysis for small scale fixed speed wind generator systems(Stellenbosch : Stellenbosch University, 2018-03) Dumakude, Niniva; Kamper, M. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: Very recently has the concept of a slip coupler been introduced in wind energy applications. It forms part of the SS-PMG and there is extensive work being done in evaluating the technology. It's application is for a fixed speed and fixed blade pitch stall controlled wind turbine. The stall controlled wind turbine's aerodynamic performance is evaluated using BEM and CFD for various wind conditions where the gust winds are evaluated in case they pose a potential threat in the health of the system components. The optimum energy capture for proposed wind site is established and a cost analysis is performed in order to establish what size turbine and cost would yield optimum energy production per cost. A cost model for the SS-PMG system is proposed whereby a discrete cost package for the slip-PMC and the PMSG are developed, with the use of mass ratios of the SS-PMG components and some data from electrical machines manufacturers. A simple cost model for the wind turbine blades is established and with the available cost models, the drive train cost evaluation is performed in evaluating the competitiveness of the Aero Energy and the NREL Phase VI wind turbine. To minimise shaft stifiness, the slip-PMC is introduced in small-scale wind turbines. The analysis of such machines is proposed and evaluated. A spoke-mount PM coupler configuration is proposed and its performance is evaluated against that of the the surface-mount PM coupler which is widely studied in most literature. The machine performance sensitivity to magnet dimensions is done in a form of a optimisation of a PM rotor for a fixed wound rotor. The spoke-mount PM machine shows an improvement in torque performance for the same amount of PM material as the surface-mount PM machine. The slip-PMC torque performance is dependent on the effective resistance of the coils, thus assuming dc resistance only yields inaccurate prediction, especially at high frequencies. Thus slot leakage effect is accounted by introducing a multiple layer coil modelling technique whereby the average taken when only one coil layer is considered is minimised. Additionally the ac resistance is dominant where the skin depth of penetration is less than the actual coil depth, thus it is deemed necessary to evaluate the model performance assuming ac resistance at high slip frequencies. The low core loss which is deemed negligible in the design optimisation of such a machine is demonstrated using a static and time harmonic model. The conduction losses which are quite dominant and accounted for in the design optimisation are illustrated. Finally the slip-PMC concept is tested test rig prototype which shows is in agreement with the static FEM analysis method, in effect validating the slip-PMC concept.