Performance Comparison of Large-scale Design-optimised Non-overlap and Overlap Winding Wound Rotor Synchronous Generators

The use of non-overlap windings rather than overlap windings is a topic for debate. Non-overlap windings are generally cheaper and easier to manufacture, but result in a high amount of magnetomotive force sub- and higher-order harmonics. A strategy to reduce these harmonics has been previously published and this study aims to provide a performance comparison of a large-scale wound rotor synchronous generator with a modified non-overlap winding and a classical overlap winding. Hence, design optimisations of a 16/18 and 16/72 pole/slot grid-connected 3 MW wound rotor synchronous generator for medium-speed wind generation are conducted. The optimisations are performed using the modified method of feasible direction gradient-based optimisation because of its simplicity and fast results. Optimal solutions for the 16/18 and 16/723 MW models are obtained and the performance of the solutions compared. The results show that the 3 MW 16/18 model performs favourably against the 3 MW 16/72 model, especially regarding the lower active mass.