Terminal voltage control of a wind turbine driven isolated induction generator using stator oriented field control

This paper presents the voltage build up process and terminal voltage control in an isolated wind powered induction generator driven by a variable speed wind turbine using stator flux oriented vector control. Here three-phase induction generator is excited using a PWM inverter/rectifier connected to a single capacitor on the DC side. Wind powered isolated induction generators have an input, wind, which is not controllable, but they can be set to operate within a given variation of speed. Unlike a grid connected induction generator, in an isolated induction generator there should be a control system that keeps the DC bus voltage at a constant value when the speed of the rotor is varied. This paper present the control system to maintain the DC bus voltage at a constant value by varying the flux in the induction generator when the rotor speed is varied. During voltage build up the variation of magnetizing inductance is taken into consideration.