Optimization and comparison of flux-concentrating Nd-Fe-B generator considering variable power factor and wind conditions for a 6MW offshore wind turbine

摘要

A large proportion of offshore wind turbine designs are now based on directly driven permanent magnet synchronous generators using rare earth materials. During last few years, the price of Nd-Fe-B has increased and fluctuated significantly. The large price fluctuations encourage us to look at flux-concentrating Nd-Fe-B generator (where flux-concentrating characteristics helps to increase flux density in the air gap) and optimize that for offshore wind turbine generator. In this paper, a 6 MW generator using Nd-Fe-B magnet is designed analytically in MATLAB, where magnets are placed between magnetically conducting pole shoes to reinforce the air gap flux. The generator design is optimized for the best performance machine and lowest cost of energy. Further optimization is performed to compare the results with a 6 MW surface-mounted Nd-Fe-B generator. It is found that, the flux-concentrating Nd-Fe-B generator gives better cost of energy compare to surface mounted Nd-Fe-B generator. The effect of variable power factor and sensitivity to wind conditions are also estimated in this study.