Standalone DFIG based power system supported by energy storage or auxiliary power unit

A paper describes cooperation of the standalone doubly fed induction generator with an energy storage or auxiliary power unit coupled with the DC bus of the main back-to-back power electronics converter. The control method and the energy management of the energy storage coupled through a bidirectional DC/DC converter with a DC-link of the main back-to-back converter is proposed. The control method allows to stabilize the stator voltage in a wide range of speed and load during deficit of mechanical energy on the shaft, and charging the energy storage during mechanical energy surplus. The overcharge and deep discharge protections are applied in the control method of the energy storage converter. The management structure for the system with auxiliary power source is simplified in relation to the energy storage support, as in the case of auxiliary power a protections of overcharge and deep discharge are not applicable. A laboratory tests results of the standalone system supported by a supercapacitor are shown.