Modal analysis of a grid-connected DFIG-based WT considering multi-timescale control interactions

• Published in: Journal of engineering (Stevenage, England) England), 2017, Vol.2017 (13), p.1118-1123
• Main Authors: Wan, Minhui, Hu, Jiabing
• Format: Article
• Language: English
• Subjects: angular velocity control; asynchronous generators; DC‐link voltage control; doubly fed induction generator; electric current control; grid‐connected DFIG‐based WT; machine control; modal analysis; multi‐timescale control interactions; multi‐timescale control loops; output active‐reactive power tracking; phase locked loops; phase‐locked loop; position control; power generation control; power grids; rotor current control; rotor speed control; rotors; stability; system stability; voltage control; weak AC grid condition; wind turbine system; wind turbines
• ISSN: 2051-3305; 2051-3305
• DOI: 10.1049/joe.2017.0503

In a grid-connected doubly fed induction generator (DFIG)-based wind turbine system, the multi-timescale control loops of DFIGs work together to keep the output active/reactive power tracking their references. In weak AC grid condition where the grid impedance cannot be neglected, interactions among those control loops are very strong. This study presents a modal analysis of the system containing a DFIG. The DFIG model for analysis considers multi-timescale control and its interactions. The effect of bandwidths of rotor speed control, phase-locked loop, DC-link voltage control and rotor current control on system stability is presented. Interactions among those control loops are explored. The analysis results indicate that the interactions among multi-timescale control are strong and will have an effect on the stability and the dynamics of the DFIG system under weak AC grid condition.