Voltage-Dip Analysis of Brushless Doubly Fed Induction Generator Using Reduced T-Model

This paper presents the performance analysis of brushless doubly fed induction generator (BDFIG) during symmetrical voltage dips. The equivalent circuit consists of resistances and dependent voltage sources in its rotor loop; thus, its voltage-dip analysis becomes more challenging. To overcome such difficulty, a reduced full-order model of the BDFIG into a new T-model is presented. A detailed mathematical analysis is performed subject to voltage-dip conditions. The time variation for the machines fluxes, electromotive forces, voltages, currents, and active and reactive powers are analyzed and their analytical approaches are derived. The current/voltage stress of power converter during voltage dip is discussed. The accuracy of the proposed T-model and the theoretical voltage dip is confirmed via experimental tests on a 3-kW BDFIG, and simulation results of a 2-MW BDFIG.