DescriptionBackground: Wind energy driven by favorable Cost of Energy (CoE) is taking bigger share in electricity generation. The offshore sector has experienced large growth due to higher wind potential and lower social impact, even though CoE is significantly higher compared to onshore. With the constant pressure to reduce CoE, offshore wind industry has been a strong driver of new machine concepts particularly in the past decade with the development and deployment of offshore wind turbines where direct drive slow rotating generators have been foreseen as advantageous.
Depending on the application, trends of development of electrical machines have focused on energy savings, i.e. higher efficiency margins for industrial motors and high torque density motors – a trend dominantly driven by the automotive and wind turbine industry. Most recent development directions in wind turbine generator design have focused more and more on alternatives to permanent magnet synchronous machines (PMSM), that are less dependent on rare earth elements (Nd and Dy in NdFeB based magnets). With focus on torque density and less dependence on rare earth materials, superconducting machines have been proposed and studied as WT generators worldwide. Yet, no in-field demonstration has been accomplished so far although several companies are working on this goal.
Structure of the tutorial: The tutorial starts with basic principles of superconducting machines, such as motivation for using superconductors in electrical machines and the potential applications that are expected to benefit from this technology. The brief history of superconducting machines is followed by a presentation of past and present projects and prototypes of the technology.
An introduction to superconductivity and industrial conductors which could be used in wind turbine generators, including low temperature superconductors (LTS), first and second generation superconductors (1G and 2G HTS), and the latest development of MgB2 wires will follow. In order to have a comprehensive view point of merits and limitations of each conductor, physical properties of the conductors and materials, AC losses mechanisms, electrothermal instability characteristics and the overview of the production methods will be presented, followed by the present cost and cost forecast in the present and markets to come.
After presenting and comparing different superconducting machine topologies, including topologies that use bulk superconductors, HTS machines and fully superconducting machines, where both rotor and stator contain superconductors, the tutorial presents a design process of a 10MW superconducting wind turbine generator based on both 2G HTS and MgB2 superconductors. Simplified design process carried out will be a combination of conceptual, analytical and FE based approach where several key accepts of the design will be in the focus of the tutorial. Particular attention will be given to electromagnetic, structural and thermal aspect of the design including state of the art in AC loss calculation together with challenges associated with such calculation.
|Period||10 May 2015|
|Event title||IEEE International Electric Machine and Drives Conference: null|
|Location||Coeur d’Alène, Idaho, United States|