طراحي و كنترل توربين -ژنراتورهاي محركه مستقيم مبتني بر ماشين هاي شار محور و مبدل هاي الكترونيك قدرت چند سطحي

چكيده انگليسي :

Design and Control of Direct Driven Wind Power Systems using Axial Flux Generators and Multi level Converters Maryam Shokri m shokri@ec iut ac ir Date of Submission 2012 09 19 Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Persian Supervisor Ahmadreza Tabesh a tabesh@cc iut ac ir Abstract Currently wind energy systems due to maturity in technologies are among the most promising renewable energy resources Several countries have now considered deployments of wind farms as a part of sustainable energy solutions in energy development plans Three types of fixed speed partial variable speed and fully variable speed topologies are commonly used in wind turbine generators Recent high power wind turbine generators mainly use variable or partial variable speed topologies to achieve higher efficiency Direct drive wind turbine generators as an efficient alternative for high power wind power units have been of interest of researches during recent years In a direct drive topology for a wind power unit the gearbox is eliminated and the low speed shaft of the turbine is directly connected to the generator This topology improves the efficiency of the wind power units and it also reduces the maintenance costs which are significant due to modular structure of wind farms The main challenges for deployment of direct drive topologies are development of low speed less than 100 rpm high power generators with suitable power electronics interfaces for capturing and delivering the maximum wind power to a grid This thesis deals with topologies for direct drive wind turbine generators which address the above challenges In the first part of the thesis a poly phase axial flux machine will be investigated as a promising solution for low speed high torque generators Due to high power density axial flux machines can be used in direct drive wind power units with limited spaces The thesis investigates the dynamic model of an axial flux machine and develops a generalized control method for poly phase machines based on conventional qd frame of reference that have been widely used in literatures In the second part of the thesis applications of newly developed modular multi level converters for grid integration of wind units using poly phase axial flux machines will be presented In the proposed topology for capturing and tracking maximum wind power the output voltage of the poly phase axial flux machine is rectified to an almost ripple free dc voltage via using series connected three phase diode bridge rectifiers Then the dc voltage is converted to a multi level pulse width modulated ac voltage via using a modular multi level converter The control provision that is used for the proposed topology is to adjust the rotor speed of the generator via control of real power flow in the converter Meanwhile injected reactive power at the grid side converter has been also adjusted via using a feedback control loop that uses modulation index as an input control signal The significant features of the suggested topology for direct drive wind turbine generators are i using a poly phase machine in conjunction with diode interfaces which hugely reduce ripples and the required filter capacitor ii using a multi level topology that reduces the switching frequency which in turn improves the efficiency of the converter especially at high power applications The performance of the suggested topology has been tested via simulation of a study system including a 9 phase permanent magnet axial flux machine and a power electronic interface including a 3 stage diode rectifier and a 5 level converter Keyword Direct drive wind power Modular multi level converters Permanent magnet axial flux machines Poly phase axial flux machines

شكري، مريم

طراحي و كنترل توربين -ژنراتورهاي محركه مستقيم مبتني بر ماشين هاي شار محور و مبدل هاي الكترونيك قدرت چند سطحي

نيروگاه هاي بادي , اينورترهاي چند سطحي بخش پذير , ژنراتورهاي شار محور چند فاز