Generator systems for wind turbines

This paper gives an overview of generator systems for wind turbines. First, the basic requirements for the drive system are related to the working principles of wind turbines. Next, the paper describes the three classical generator systems with their strengths and weaknesses: constant speed, variable speed with doubly-fed induction generator and variable speed with direct-drive generator. Besides, alternative generator systems and trends are discussed. There is a clear trend towards variable speed systems. Converters and permanent magnets are increasingly used because of their decreasing prices.