PROJECT TITLE :

Control Scheme for DC Voltage Regulation of Stand-Alone DFIG-DC System - 2017

ABSTRACT:

A scheme for the dc output voltage management of a stand-alone DFIG-dc system is proposed. Any load variation on the dc link will primarily affect the active part of stator current. The modification in reactive part of a stator current is minimum, that can conjointly manifest in an exceedingly slight variation within the stator voltage and frequency. The management philosophy is meant such that the active rotor current is determined by a vigorous stator current, whereas the dc-link voltage is made and maintained by a flux loop with a reactive rotor current. Stator voltage/flux ratio is nearly constant, since the flux is set by the voltage loop. This will indirectly maintain stator frequency around a constant reference frequency. The main benefits of this scheme are direct control of the load current, load independent dc voltage regulation, indirect stator frequency regulation, and stator voltages sensorless. Control scheme is verified experimentally and demonstrated with results for 2 cases: with and without the use of step-down transformer between stator and rectifier.