Topology Comparison of Superconducting Generators for 10-MW Direct-Drive Wind Turbines

Abstract

This paper aims at finding feasible electromagnetic designs of superconducting synchronous generators (SCSGs) for a 10-MW direct-drive wind turbine. Since a lower levelized cost of energy (LCoE) increases the feasibility of SCSGs in this application, twelve generator topologies are compared regarding their LCoE in a simplified form of levelized equipment cost of energy (LCoEeq). MgB2 wires are employed in the field winding. Based on the current unit cost and critical current density capability of the MgB2 wire at 20 K, the topologies with more iron have a much lower LCoEeq than the topologies with more non-magnetic cores. The fully iron-cored topology with salient poles has the lowest LCoEeq. Then a scenario study shows that the difference of LCoEeq between the topologies will become much smaller when the unit cost of the MgB2 wire drops to a quarter and the current density capability of the MgB2 wire increases to 4 times. Then the topologies with more non-magnetic cores will become comparable to those with more iron. Aiming at a lower LCoEeq to increase the feasibility of SCSGs for large wind turbines, those topologies having the most iron in the core are the most promising for both now and the long term. If low weight is required, the topologies with more non-magnetic cores should be considered.