Proposed controller and stability analysis for DFIG to suppress stator flux oscillations during autonomous operation

Abstract

Doubly fed induction generator (DFIG) driven wind turbines experience poorly damped stator flux oscillations at frequencies around the fundamental, limited low voltage ride through capability and output power fluctuation. In this study, a proposed controller to mitigate stator flux oscillations of DFIG is proposed during autonomous operation mode. In addition, super-capacitors based energy storage is integrated to manipulate wind speed vagaries and contribute to load demand. A 53rdorder small-signal analytical model and eigenvalues study is carried out to optimally determine control system parameters and pinpoint latent system dynamics and stability margins under various operation conditions. Also, a detailed non-linear system is modelled and simulated in Matlab/Simulink environment to assure small-signal model results. The results obtained confirm the accuracy of the analytical model and explore the significance of the proposed damping controller to mitigate stator flux oscillations even during contingencies.