Development of a new connection scheme for variable-speed wind turbines using squirrel-cage generators

Nowadays it is mandatory for wind generation facilities to meet grid requirements much higher than the ones they had to comply with in the past, due mainly to the desire for an increase in the penetration of this type of energy source (S.A. Papathanassiou and N.D. Hatziargyriou, 2001). These requirements, along with the desire of variable speed operation, makes necessary the use of power electronics in the connection to the grid, by means of different topologies depending mainly on the type of generator used (induction, both doubly-fed or squirrel cage, or synchronous). The paper presents the development of a new connection scheme applied to a variable speed generation system using a squirrel cage machine, whose main goal is to increase the effective switching frequency in the grid side, in order to reduce the harmonic content of the injected currents