The goal of the project is to investigate a new topology of generator system for wind turbines, consisting of a continuous variable transmission gear box and a synchronous generator with access to the rotor field winding.Focus is put on reactive power control and fault ride through capabilities of the generator.The prime mover is an induction motor, supplied from a 3 phase SFC and controlled with FOC. The generator has a constant speed and variable torque. Excitation voltage is supplied from a DC/DC converter.First, analytical models of the SG and IM are developed. The models are verified and validated through simulation before laboratory implementation.Principles of operation during grid connection and transient faults are presented. A setup was built in the laboratory. The control was achieved through dSpace. Three phase voltage faults were experimented. Results and conclusions are presented.