This article investigates the structural optimization of a 20-MW offshore wind generator to minimize the torque ripple and mass. The surface-mounted permanent magnet topology will be chosen for the generator. In addition, the double-layer armature winding configuration will be utilized. The direct-drive technology will be adopted to increase the reliability of the offshore wind energy conversion system. The multi-objective optimization of the generator is carried out based on the particle swarm algorithm. Results show that the torque ripple of the optimal model is significantly reduced to as much as 0.41% at full-load conditions making the configuration suitable for the high-power offshore wind generator.

This article aims at reducing the cost of energy by targeting the optimal power of the wind generator of offshore wind farms in a region in Vietnam. The research employs various scaling laws for mass and cost calculations. The calculations are implemented using wind data of a specific region on the South-Central Coast. The permanent magnet synchronous generator with high efficiency, light-weight, and compact design will be used for the wind generator. The levelized cost of energy as a function of the generator’s nominal power is then built to figure out the optimal power of the wind generator. Results show that future offshore wind farms with monopile foundations having a mean wind speed of about 6.5 m/s should be installed with a turbine's nominal power of 7 MW.