Analysis of Grid-Side Converter Dynamics and Dc-Link Controller Design in DFIG-Based Wind Turbines

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Abstract

This paper deals with the analysis of the grid side converter (GSC) dynamics and dc-link controller design in doubly fed induction generator (DFIG) based wind turbines. In this way, at first the current controller design for the GSC is proposed, and then power flow direction in rotor-side and grid-side converters at different slips is determined. Next, the dc link dynamics is extracted based on the instantaneous power exchanged between the converters and the dc-link capacitor. For the dc-link dynamics extraction, the dynamics of the GSC interface filter is taken into account. It is shown that the dynamics of the dc-link voltage by taking the dynamics of the interfaced filter into account exhibits no minimum phase behavior, and this in turn results in limitation on the achievable appropriate dynamic response. Then, the paper deals with the dc link controller design and selection of controller parameters. Finally, performance of the system under study is examined by the time domain simulations using MATLAB-SIMULINK software.

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