Control of doubly-fed induction generators in a multiple wind turbine system operating in a stand-alone mode

This paper presents a method for controlling a multiple wind turbine system using doubly-fed induction generators (DFIG) in a stand-alone (i.e., off grid) operation mode. The DFIG operates in stand-alone mode by utilizing extracted aerodynamic energy for maintaining the output voltage under load. A synchronous reference frame is utilized in the modeling of DFIG and the formulation of the control law. A power coordinator controller distributes the real and reactive load power among multiple wind turbines according to their wind speeds. A three-phase voltage balancing control scheme maintains balanced output voltage under unbalanced loading conditions. The proposed control method is shown to be effective by computer simulations.