A Wind Turbine Generator Design and Optimization for DC Collector Grids

This article presents the design and optimization of a multiphase doubly excited generator (DEG) for wind turbine applications in a dc grid. The DEG has two rotors: 1) a wound field excited (WFe) rotor, which in principals is similar to a conventional synchronous generator (SG) and 2) a surface-mounted permanent magnet excited (PMe) rotor that has a similar operation as a PM generator. The DEG is connected to a multileg passive rectifier whose output is connected to a dc wind grid. The dual rotor topology allows modification of the output power and voltage of the DEG while eliminating the need for an active power electronic converter. The DEG is parametrized and undergone a multiobjective optimization solved by employing a differential evolution algorithm (DEA). The DEG output power, mass, and efficiency are optimized subject to a list of prescribed constraints. To verify the design procedures a small-scale DEG is built and tested in the laboratory, whose results are presented in this article.