Research towards large scale superconducting wind generators
Final Report Abstract
With the rapid development of the second generation high temperature superconductors (HTS) and the increasing availability of this material by several manufacturers from all over the world, the usage in power devices has become more and more the focus of attention. The high current carrying capacity and the lack of electric losses under direct current operation enable power devices with higher power densities and better efficiencies compared to conventional ones. In relation to low temperature superconductors the second generation HTS tapes further allow a more economic operation temperature which is far above the temperature of liquid helium. Due to the continuous increase of the global installed wind power there is a driving demand for wind turbine generators with higher power ratings and reliability while at the same time reducing the costs and the volume-weight ratio of such machines. The enhancement to higher power ratings, especially in the offshore sector, means a reduction of the levelized cost of energy and therefore a more economic generation of wind energy. Whereas state of the art geared and direct-drive wind turbines are difficult to scale up, superconducting machines could reach power ratings above 10 MW and keeping the overall wind turbine system dimensions small. In this project, possible superconducting generator topologies for use in 10 MW wind generators are evaluated and a detailed consideration of the novel double stator flux modulation generator (DSFMG) and electrically excited synchronous generator (EESG) is undertaken. As a result, a complete 10 MW model of the DSFMG is developed. The two generator models are also investigated for their behavior in the event of a short-circuit current caused by a grid-side fault. It is shown that the special design of the DSFMG can significantly reduce the short-circuit currents and the torque peaks that occur. Furthermore, second generation HTS tapes and, for the first time, ferromagnetic materials are tested under cryogenic conditions. In addition, a series of superconducting coils are designed and constructed that better meet the requirements of coils in real generator applications in terms of design and size than the first demonstration coils. A novel winding method that completely eliminates the need for electrical insulation between the individual coil windings is used, thus making it possible to obtain extremely robust superconducting coils. The coils are successfully tested with regard to their superconducting properties. In addition, the coils are investigated both with measurements and with the aid of a specially developed simulation model with regard to their improved stability and the dynamic response changed by the novel winding method.
Publications
- ”Design of a Superconducting DC Demonstrator for Wind Generators,” in IEEE Transactions on Energy Conversion, vol. 33, 2018
Y. Liu, et al.
(See online at https://doi.org/10.1109/TEC.2018.2846721) - “A Novel Dual-Stator HTS Linear Vernier Generator for Direct Drive Marine Wave Energy Conversion,” in IEEE Transactions on Applied Superconductivity, vol. 29, no. 5, 2019
Y. Zhou, et al.
(See online at https://doi.org/10.1109/TASC.2019.2898334) - “A Novel HTS Wind Generator Having Permanent Magnets Between the Rotor Pole-Tips,” in IEEE Transactions on Applied Superconductivity, vol. 29, no. 5, 2019
Y. Cheng, et al.
(See online at https://doi.org/10.1109/TASC.2019.2908581) - “Comparison of 2D simulation models to estimate the critical current of a coated superconducting coil”, in Supercond. Sci. Technol. 32, 2019
Y. Liu, et al.
(See online at https://doi.org/10.1088/1361-6668/aae960) - “A Novel Modular Stator Fractional Pole-Pair Permanent Magnet Vernier Machine with Low Torque Ripple for Servo Applications,” in IEEE Transactions on Magnetics, 2020
R. Li, et al.
(See online at https://doi.org/10.1109/TMAG.2020.3017663) - “Design and Optimization of an HTS Claw-Pole Machine,” in IEEE Transactions on Applied Superconductivity, vol. 30, no. 4, 2020
Y. Zhang, et al.
(See online at https://doi.org/10.1109/TASC.2020.2977001) - “Development of no-insulation racetrack coils wound with second generation high temperature superconductor tapes for a stator system for wind generators”, in IEEE Transactions on Applied Superconductivity, vol. 30, 2020
F. Schreiner et al.
(See online at https://doi.org/10.1109/TASC.2020.2969112) - „Comparison of Electromagnetic Performance of 10-MW HTS Double-Stator Flux Modulation Generators With Different Topologies”, in IEEE Transactions on Applied Superconductivity, vol. 30, 2020
Y. Cheng et al.
(See online at https://doi.org/10.1109/TASC.2020.2975153) - „Fluorescent thermal imaging of a quench in insulated and non-insulatedREBCO-wound pancake coils following a heater pulse at 77 K”, in Supercond. Sci. Technol. 33, 2020
R. Gyuráki et al.
(See online at https://doi.org/10.1088/1361-6668/ab6dc0) - “Study of contact resistivity of a no-insulation superconducting coil”, in Supercond. Sci. Technol. 34, 2021
Y. Liu, et al.
(See online at https://doi.org/10.1088/1361-6668/abd14d)
