Designing and Basic Experimental Validation of the World's First MW-Class Direct-Drive Superconducting Wind Turbine Generator

Abstract

High temperature superconducting (HTS) technologies are expected to be a key enabler for lightweight and costeffective direct-drive (DD) trains for large wind turbines. This paper reports the designing and basic experimental validation of the world's first full-scale DD HTS generator demonstrated on a commercial wind turbine. The HTS generator has its rotor with an HTS field winding working below 30 K, which is achieved by using off-the-shelf Gifford-McMahon cryocoolers. The stator of the generator is essentially conventional, except that the armature winding has four segments to limit fault torques in case of sudden short circuits due to converter failures. Compared to an existing DD permanent magnet generator on the turbine, the air gap shearing stress of the HTS generator is doubled, and the weight is reduced by 24%. The overall design requirements from the turbine integration perspective, as well as the topological considerations, are first described in this paper. The electromagnetic and cryogenic designs are then presented, followed by performance testing of HTS coils. The basic experimental validation shows that the cryogenic design

Magnetization and Losses for an Improved Architecture of Trapped-Flux Superconducting Rotor

“…are not singled out in the FE model, where the averaged properties of the superconductor plus the substrate are considered. In addition, variations in the material properties at these temperatures begin to depart from the trends observed at higher ones [5]. However, due to the ferromagnetic materials surrounding them, the stacks are expected to work in a similar way as in [9] with a magnetic flux during magnetization and operation primarily in the normal direction and under a similar range of temperatures.…”

“…1) and its relatively high critical current density. This simple arrangement of the magnetic flux sources simplifies the construction of the rotor compared with other approaches that require current leads [5], since the rotor is an element of great complexity due to the required helium cooling system circulating between an internal fixed insert and the external moving sleeve [15]. The moving sleeve, which provides the mechanical attachment using dovetails for the electromagnetic-active component of the rotor, is maintained at 25 K during operation.…”

“…However, the application of this machine in airliner propulsion requires the fan for a turbopropulsor to move at a slow speed, which would exclude this approach unless a gearbox, with its associated weight, is added. Similar to wind generation, the trend has been to eliminate this element [5], thus, for airliner propulsion a low speed/very high torque electric motor is required. This is a highly demanding design that can be achieved either by acting on the currents of the stator or the flux produced by the rotor or both given the sharp increase in performance that is needed.…”

Performance of Multi-Layer and Stator-Shifting Fractional-Slot Concentrated Windings for Superconducting Wind Turbine Generators Under Normal and Short-Circuit Operation Conditions

“…In other words, they work as a shield to limit the AC loss production in the HTS field winding. Multi-layer insulation is placed next to the HTS field winding as a thermal barrier but this part does not have induced losses [23], [24].…”

Investigation Into Multi-Phase Armature Windings for High-Temperature Superconducting Wind Turbine Generators

“…Thus, they are being considered in 10+ MW offshore direct-drive (DD) wind turbines to reduce the levelized cost of energy (LCOE) [1]- [6]. The state of the art of HTS generators for wind turbines is that within the EcoSwing project a full-scale 3 MW-class DD HTS generator has been successfully commissioned on a real wind turbine [7], [8].…”