Control of a squirrel cage induction generator wind farm connected to a single power converter

The aim of this paper is to analyze the control of several wind power generators based on squirrel cage induction generators with one common power converter. This configuration is especially useful for offshore wind farms with a VSC-HVDC transmission. A comparison with a configuration where each generator is connected to one power converter, is done focusing in the total power extraction. Scalar-controlled squirrel cage induction generators have been implemented in both cases. The control scheme has been modified implementing an aggregated model in order to allow the common converter to perform appropriated control tasks. A fault ride-through control protects the DC bus from overvoltages, it varies the torque and slip reference to limit the total output power. Results have been validated by means of simulation in both scenarios showing the differences in the total power obtained and the influence of the generator operating point. The performance of the system under onshore grid faults has been simulated.