Candid inquest on modeling methods of doubly fed induction generator, and corroboration through simulation study

Abstract

The doubly fed induction generator (DFIG) based wind energy conversion system (WECS) is the ubiquitous system than its counterpart, the squirrel cage induction generator (SCIG), because of its attractive features such as the variable speed operation capability, the low operating noise, the mechanical stress mitigation, the flexible control over active and reactive power flows etc. Simulation studies on nascent WECSs necessitate the accurate and the restitution readied (for non-idealities) models of DFIG as inexact models will make past grave denouements in the stake. Generally, the modeling of electromagnetic machines can be realized as a differential equation (linear/non-linear) or a transfer function (Z/S domains) or in the state space form. Amid the host of DFIG models archived hitherto, there is neither a perennial nor a pristine model. This paper attempts to rekindle existing dynamic models of DFIG to assert the nuance in them, which will succor in culling the apposite model for nascent inquests, unequivocally. The tenet of each model is analyzed through mathematical equations and a comprehensive MATLAB 13 (Simulink-ode 23tb-solver) based simulation study. Comparison is on the basis of electromagnetic torque, rotor speed, rotor currents, real and reactive powers on stator and rotor side, etc.

Active and Reactive Powers Control of DFIG Based WECS Using PI Controller and Artificial Neural Network Based Controller

“…The stator active and reactive powers vector uncoupled control can be accomplished by orienting the Park frame (d,q) so that the (d) axis is aligned with the stator flux [2][3][4][5][6][7][8]. Hence, the stator flux becomes:…”

“…The MPPT control strategy is based on adjusting the rotor speed to track the optimal reference power. The rotor speed can be adjusted by controlling electromagnetic torque of the DFIG rotor [3][4][5][6][7][8][9].…”

“…Variable speed wind turbines are generally a megawatt class, especially in wind farms. Currently, doubly fed induction generator based wind turbines are the preferred choice for high capacity wind farms due of its unique features such as flexible control, low cost, high efficiency and ability to independently control active and reactive powers exchange with the grid system [1][2][3]. The DFIG stator winding is connected directly to the grid, while its rotor is connected indirectly to the same grid via a back-to-back power converter.…”