Extended Direct Voltage Control of the Stand-Alone Double Fed Induction Generator

A stand-alone power system with a doubly fed induction generator DFIG is described. A Direct Voltage Control DVC for the stand alone operation is based on the stator voltage vector represented in rotating polar frame. A synchronization of the produced stator voltage vector with a reference voltage vector produces an output signal, used as a reference rotor current angular speed. This way the control method does not need any information of the rotor speed or position. An amplitude and frequency control uses the positively rotated polar frame and positive sequence components, whereas the negative sequence components for voltage asymmetry correction are used. Using positive and negative sequence components an unbalanced load can be supplied.