LINEAR MODAL ANALYSIS OF DOUBLY-FED INDUCTION GENERATOR (DFIG) TORSIONAL INTERACTION: EFFECT OF DFIG CONTROLLERS AND SYSTEM PARAMETERS

Clean energy sources like wind energy have received great attention due to growing demand for electrical energy and increase of environmental pollution. The Doubly Fed Induction Generators (DFIGs) are also in common use due to their ability to control the reactive power with no need for capacitor banks. Existence of active and reactive power controllers in DFIG may provide the possibility of adverse interaction with torsional modes of the turbine-generator set. Because of the importance of this phenomenon, in this paper, the interaction of DFIG controllers with other components of the wind turbine-generator, especially torsional modes, has been studied. As the variable speed wind turbine is used, the effects of rotor speed variation on the torsional interaction with the active and reactive power controllers have been investigated. Moreover, the effects of variation of other parameters such as local load, and mechanical and electrical parameters of DFIG on the torsional interaction have been studied. In order to study and analyze this phenomenon, the linear modal analysis is used. The obtained results demonstrate the effects of parameters in possible occurrence of interaction between the DFIG controllers and the DFIG turbine generator set. In addition, the obtained analytical results are verified via time domain simulation.