Experts from DNV GL will showcase their expertise during the conference in both presentations and poster sessions:
Authors: A. Kumar, O. Hugues-Salas, B. Savini and W. Keogh
Poster title: D15: Tower Based Load Measurements for Individual Pitch Control and Tower Damping of Wind Turbines
Date: Thursday 6 October
Room: Main Hall
Session: Poster Session 2
The cost of IPC has hindered adoption outside of Europe despite significant loading advantages for large wind turbines. In this work we presented a method for applying individual pitch control (including for higher-harmonics) using tower-top strain gauge feedback instead of blade-root strain gauge feedback. Tower-top strain gauges offer hardware savings of approximately 50% in addition to the possibility of easier access for maintenance and installation and requiring a less specialised skill-set than that required for applying strain gauges to composite blade roots. A further advantage is the possibility of using the same tower-top sensor array for tower damping control. This method is made possible by including a second order IPC loop in addition to the tower damping loop to reduce the typically dominating 3P content in tower-top load measurements. High-fidelity Bladed simulations show that the resulting turbine spectral characteristics from tower-top feedback IPC and from the combination of tower-top IPC and damping loops largely match those of blade-root feedback IPC and nacelle-velocity feedback damping. Lifetime weighted fatigue analysis shows that the methods allow load reductions within 2.5% of traditional methods.
Presenters: W. Collier and J-M. Milian Sanz
Presentation title: Comparison of linear and non-linear blade model predictions in Bladed to measurement data from GE 6MW wind turbine
Date: Thursday 6 October
Room: Niemann Hall
Session: Modelling and simulation technology 4
The length and flexibility of wind turbine blades are increasing over time. Typically, the dynamic response of the blades is analysed using linear models of blade deflection, enhanced by various ad-hoc non-linear correction models. For blades undergoing large deflections, the small deflection assumption inherent to linear models becomes less valid. It has previously been demonstrated that linear and non-linear blade models can show significantly different blade response, particularly for blade torsional deflection, leading to load prediction differences. There is a need to evaluate how load predictions from these two approaches compare to measurement data from the field. In this paper, time domain simulations in turbulent wind are carried out using the aero-elastic code Bladed with linear and non-linear blade deflection models. The turbine blade load and deflection simulation results are compared to measurement data from an onshore prototype of the GE 6MW Haliade turbine.
Presenters: A. Beardsell, W. Collier and T. Han
Presentation title: Effect of linear and non-linear blade modelling techniques on simulated fatigue and extreme loads using Bladed
Date: Friday 7 October
Room: Diesel Hall
Session: Aeroservoelasticity, loads, structures and materials 1
There is a trend in the wind industry towards ever larger and more flexible turbine blades. Historically, the dynamic response of wind turbine blades has been analysed using linear models of blade deflection which include the assumption of small deflections. For modern flexible blades, this assumption is becoming less valid. In order to continue to simulate dynamic turbine performance accurately, routine use of non-linear models of blade deflection may be required. In this paper, Bladed is used to compare load predictions using single-part (linear) and multi-part (non-linear) blade models for several turbines. The study examines the impact on fatigue and extreme loads through reduced sets of load calculations based on IEC 61400-1 ed. 3. Differences in edgewise-torsional coupling and in edgewise damping between the multi-part and single-part models are noted, and a causal link is identified between torsional blade dynamics and changes in ultimate load results.
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