Maximizing Energy Extraction from Direct Grid Coupled Permanent Magnet Synchronous Generators

Bakbak A., Canseven H. T. , Altıntaş M., Ayaz M. , Meşe E.

2021 IEEE Applied Power Electronics Conference and Exposition (APEC), Arizona, United States Of America, 14 - 17 June 2021, pp.981-988

  • Publication Type: Conference Paper / Full Text
  • Doi Number: 10.1109/apec42165.2021.9487163
  • City: Arizona
  • Country: United States Of America
  • Page Numbers: pp.981-988


Direct Grid Connection of Permanent Magnet Synchronous Generators (PMSG) has well-known disadvantages such as unstable operation and poor energy extraction when the mechanical power from prime mover tends to change. Wind energy systems are the best examples to see these two drawbacks. On the optimistic side, the elimination of the power electronics present certain cost advantages for the installation stage. However, the advantage may disappear due to the lack of a power electronics system for tracking maximum power point in the face of changing wind speed. This paper proposes a novel PMSG design philosophy such that optimizing PMSG design at the initial stage would compensate for the drawback arising due to lack of Maximum Power Tracking (MPPT) algorithm. Pole numbers of PMSGs, which determine the operation speed, have much more impact on annual energy yield in fixed speed systems than variable speed systems. In this study, optimization of slot/pole combination is described for direct grid coupled PMSGs to extract as much energy as possible according to wind data. A new benchmark, adequacy factor is presented to determine the slot/pole combination. Cut-in wind speed equations are derived for both variable and fixed speed applications to calculate mean power properly. An analytical comparison is carried out between fixed and variable speed operations of PMSGs in terms of annual energy yield for MW power levels. Also, an experimental comparison study is performed by using a 5 kW prototype generator. Results have shown that fixed speed wind energy conversion systems with optimized parameters have more annual energy production than variable speed systems.