Direct drive superconducting wind generators

Abstract

There are plans for a large expansion of offshore wind energy, particularly in Northern Europe where there is limited space for onshore turbines. One means to reduce the cost of offshore wind energy is to build wind farms with fewer larger turbines, reducing the number of costly offshore foundations. The emerging next generation of HTS technology, which offers the prospect of low cost high volume HTS wire production, can be used to build compact and lightweight generators at high rating and torque. These new generators will become the enabler for very large, direct drive wind turbines in the 10 MW class. Direct drive turbines also offer an improvement in reliability and effi ciency by removing the gearbox, which has been a troublesome component in many offshore wind farm projects, and replacing it with a much simpler mechanical system that is not sensitive to the misalignment or to fl uctuations in the shaft torque. Reliability is particularly important in offshore turbines where access is diffi cult and expensive and often prevented by weather conditions. Converteam UK Ltd. are in the fi nal stages of a project to design a direct drive HTS generator for this class of turbines, and to build and test a scaled prototype. Following on from this project will be the manufacture of a full size prototype and its demonstration on a 10 MW turbine. An economic analysis during earlier stages of the project calculated a reduction in the cost of energy of 17% from a 500 MW offshore wind farm by the use of this class of HTS direct drive turbines compared with the baseline case of 4 MW conventional DFIG turbines. This analysis did not include any additional cost reduction due to improved reliability and availability. 1 I ntroduction The wind turbine market is large and rapidly growing; while at the same time there has been a trend towards larger and larger turbines. Larger turbines are attractive