Modelling and dynamic performance of a direct-drive direct-grid slip permanent magnet wind generator

In this paper a transfer function model is developed to evaluate the dynamic performance of the direct-drive direct-grid connected slip permanent magnet wind generator system. The modelling of the generator is done in the dq reference frame fixed to the PM-rotor, for both the grid frequency and slip-frequency generator components. The transient response of a single, 15 kW grid-connected system to changes in turbine torque and grid voltage and frequency is evaluated. It is shown that the generator is very stable under transient turbine-torque conditions and that it acts as a filter to prevent voltage flickering. The dynamic performance is confirmed by laboratory measurements on a 15 kW direct drive slip permanent magnet generator.