Comparison Study of Superconducting Wind Generators With HTS and LTS Field Windings

Large-scale direct-driven wind turbines are preferred for offshore wind generation from the viewpoint of cost of energy and system reliability. However, direct-driven generators of traditional technology are very difficult to be scaled up to a rated power of 10 MW or above. Superconducting generators offer a candidate to fill that gap. A feasible superconducting wind generator topology has rotor field windings made of superconductors and traditional copper stator windings carrying alterative currents. Nowadays, two kinds of superconductors are available in the market: the low-temperature superconductors (LTS) and the high-temperature superconductors (HTS). They have great differences in terms of material characteristics, product performance, price, and the relevant cryogenic and refrigeration system, which have a great influence on the design of superconducting generators. In this paper, a comparison study of superconducting wind generators with HTS and LTS rotor field windings is carried out, considering the performance and cost of superconductors and the cryogenic and refrigeration system. From the viewpoint of initial capital, technology maturity, and engineering feasibility, the LTS wind generator is recommended for subscale or full-sized prototype development in the near future.