Doubly Fed Induction Generator Subject to Symmetrical Voltage Sags

• Published in: IEEE transactions on energy conversion Vol. 26; no. 4; pp. 1219 - 1229
• Main Authors: Rolán, A., Córcoles, F., Pedra, J.
• Format: Journal Article Publication
• Language: English
• Published: New York IEEE 01.12.2011; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aerogeneradors; Automatització i control de l'energia elèctrica; Circuit faults; Control algorithms; Doubly fed induction generator (DFIG); Electric machinery, Induction; Electric power system stability; Energia elèctrica; Energia eòlica; Energies; Enginyeria mecànica; Estabilitat; fault clearing; fault ride-through capability; Induction generators; Induction motors; Mathematical model; Motors; Motors elèctrics; Motors elèctrics d'inducció; Power quality; Sistemes elèctrics de potència; Stators; Steady-state; symmetrical voltage sag; Voltage fluctuations; Wind power; Àrees temàtiques de la UPC
• ISSN: 0885-8969; 1558-0059
• DOI: 10.1109/TEC.2011.2160397

The aim of this paper is to analyze the dynamic behavior of the doubly fed induction generator (DFIG) subject to symmetrical voltage sags caused by three-phase faults. A simple control algorithm is considered and assumed ideal: the rotor current in the synchronous reference frame is kept constant. This hypothesis allows the electrical transient to be solved analytically, providing a comprehensive description of DFIG behavior under symmetrical sags. The fault-clearing physics of symmetrical sags is also analyzed. That is, the fault is cleared in the successive natural fault-current zeros, leading to a voltage recovery in one, two, or three steps. This clearing process, called discrete fault clearing in this paper, results in a more accurate sag modeling than the abrupt or instantaneous fault clearing (the usual modeling in the literature). The fault-clearing process has a strong influence on the rotor voltage required to control the rotor current after fault clearing. To compare the effects of both abrupt and discrete sags, different wind turbine (WT) operating points, which determine different generated powers, are considered. This study helps in the understanding of WT fault ride-through capability.