Optimal design of hydro permanent magnet synchronous generators for improving annual cycle efficiency

Abstract In hydropower generation, the combination of permanent magnet generators and power electronic converters allows for variable speed operation and brings many advantages to the plant. Efficiency optimization is a valuable goal for the generator design. However, traditional optimization methods only optimize the rated efficiency without considering the overall efficiency improvement in the annual cycle. To overcome this drawback, this paper proposes a new design optimization method for permanent magnet synchronous generators in hydropower plants, which helps to improve the combined operating efficiency during the dry, normal, and rainy hydrological periods. First, the pre-operating conditions of the generator are obtained by studying the upstream periodic hydrological data and the optimal operating trajectory of the turbine. Secondly, an analytical model of generator efficiency under different hydrological conditions is developed based on an accurate subdomain model and weighted as the objective function. Furthermore, an improved genetic algorithm is proposed to solve the objective function to obtain the generator structural parameters. Finally, the improvement of the annual cycle efficiency of the generator is verified by simulation and experimental tests under different load conditions.