Feasibility Study of a Superconducting DC Direct-Drive Wind Generator

Superconducting (SC) direct-drive wind generators are proposed as a possible approach for offshore wind energy application. A lot of studies showed their benefits and superior performances. Small demonstrators up to several hundreds of kilowatts have been built and laboratory tested. More demonstrators will come in the future, and the success of these projects is very important for the large-scale prototypes to be realized. For most studies, the SC direct-drive generators are a synchronous generator concept. As the offshore wind farms are located far away from the land mainly due to the overall economic benefit, direct current transmission has been put forward. Hence, employing SC dc wind generators would be a good option. This enables a highly efficient and compact generator and, in addition, a new and also very efficient generator connection scheme at dc. For this reason, this paper investigates the feasibility of the large-scale SC dc direct-drive wind generator, in terms of torque, weight, and efficiency. In addition, the tape cost and commutation are discussed.