1. © O. Anaya-Lara – EWEC 2006, Athens, Greece 1 EWEC 2006 – IEA ANNEX XXI SPECIAL SESSION Assessment of structural dynamics for model validation of induction generator-based wind turbines Olimpo Anaya-Lara, G. Ramtharan Ervin Bossanyi and Nick Jenkins IEA Annex XXI Dynamic Models of Wind Farms for Power System Studies

2. © O. Anaya-Lara – EWEC 2006, Athens, Greece 2 OBJECTIVES  Suggest which representation of the rotor structural dynamics is more appropriate for a particular study to ensure the correct validation of dynamic models of Fixed- Speed Induction Generator (FSIG) and Doubly-Fed Induction Generator (DFIG) wind turbines  Develop FSIG and DFIG performance assessment during electrical transient such as three-phase faults (voltage dip) and network frequency variations  Conduct studies in GH Bladed, which offers a suitable common platform with highly developed mechanical/electrical systems of FSIGs and DFIGs

3. © O. Anaya-Lara – EWEC 2006, Athens, Greece 3 Out-of-plane blade bending In-plane blade bending Rotor structural dynamics Flexible structure of a wind turbine rotor As rotor size increases blade flexibiities becomes significant and need to be represented Blade bending motions

4. © O. Anaya-Lara – EWEC 2006, Athens, Greece 4  Single-mass model: neglects blade and shaft flexibility  Typical two-mass model: only considers shaft flexibility  Full model in Bladed: Complete representation of rotor structural dynamics (shaft and blade flexibilities) Low-speed shaft torque response (and harmonic spectrum) with full rotor structural dynamics during a 50% voltage sag (300 kW FSIG-based wind turbine) Frequency components of full rotor dynamics Frequency component of typical two-mass model Natural frequency of vibration

5. © O. Anaya-Lara – EWEC 2006, Athens, Greece 5 Assessment during a three-phase fault 300kW FSIG during a three phase fault (80% voltage drop, 20% retained voltage) 2MW DFIG during a three phase fault (85% voltage drop, 15% retained voltage)

6. © O. Anaya-Lara – EWEC 2006, Athens, Greece 6 Assessment during frequency variation 300kW FSIG-based wind farm 2MW DFIG-based wind farm Applied frequency variation at the terminal of the generators

7. © O. Anaya-Lara – EWEC 2006, Athens, Greece 7 Conclusion and recommendations  Rotor structural dynamics can influence the wind turbine response during electrical faults. Hence, for fault studies a model of the structural dynamics that includes both shaft and blades flexibilities may be more appropriate.  Rotor structural dynamics have little effect on wind turbine performance in the event of loss of generation (frequency variations), therefore a simple single-mass model representation of the rotor structural dynamics may be appropriate for this type of studies