Cascaded doubly fed induction generator for mini and micro power plants connected to grid

Mini hydropower and wind power plants have a promising future in Poland. Variable speed cascaded induction generators could be an attractive alternative to conventional double output induction generators habitually applied in mini hydropower stations. Cascaded induction generators require lower maintenance due the absence of slip rings and brushes. Unidirectional power converters can be employed in such power plants to provide simple power electronics, reduce of the maintenance and increase availability. Different topologies of rectifiers with a function of power factor correction could carry the slip power from the secondary side of the cascaded generator during the supersynchronous operation. The main benefit of these clean power rectifiers in comparison with diode rectifiers is the ability of canceling the torque harmonics of cascaded generator. The paper discuss which topology of clean power rectifiers could be applied as machine side rectifier in mini and micro power plants utilizing cascaded induction generator connected to grid.