Thomas Haas PhD Researcher
KU Leuven
Department of Mechanical Engineering Turbulent Flow Simulation and
Optimization Celestijnenlaan 300 3001 Leuven Belgium thomas.haas@kuleuven.be www.mech.kuleuven.be/en/tme
Investigation of Airborne Wind Energy Farm Performance
for Different Operation Modes Using Large Eddy Simulation
Thomas Haas1, Jochem De Schutter2, Moritz Diehl2and Johan Meyers1 1KU Leuven
2University of Freiburg In their efforts to compete with conventional wind
tur-bines, leading airborne wind energy companies an-nounced their intentions to develop utility-scale systems with multi-megawatt power yields [1] and therefore, man-ufacturers of both ground-based and on-board power generation systems engaged in the scale-up process. At these large scales, significant velocity deficits and in-creased turbulence levels are observed in the airborne system’s wake. When operating in a farm, these wakes are expected to have a high impact on the operation of downstream systems, characterized by a decreased per-formance. We propose a simulation framework combing optimal control [2] and large eddy simulations to in-vestigate the interaction between airborne wind energy systems and the atmospheric boundary layer. In this study, we consider large-scale systems operating both in pumping-mode, i.e. flying crosswind maneuvers in al-ternating reeling-out and reeling-in phases as well as in drag-mode, i.e. wings with on-board generators operat-ing at a fixed tether length. The woperat-ing-tether system is modeled as a three degrees of freedom mass-point and we derive the equations of motions using a Lagrangian-based modeling procedure. The optimal flight trajectory is computed offline by solving an optimal control prob-lem which maximizes the power generated by the system
while subject to a set a constraints. A model predictive controller is used to track the optimal trajectory when the system is subject to changes in local wind conditions due to turbulence and upstream systems. The wind environ-ment is modeled as pressure-driven boundary layer and its dynamics are computed by means of large-eddy sim-ulations using the inhouse code SPWind developed at KU Leuven. The effects of the kite system are added onto the flow using an actuator sector method that deals with the difference of length- and timescales between flow and system dynamics. The objective of the work presented here is to investigate each generation mode in terms of wake characteristics and assess their effects on system performance for different layouts of airborne wind energy farms.
References:
[1] Kruijff M., Ruiterkamp R.: A Roadmap Towards Airborne Wind En-ergy in the Utility Sector. In: Schmehl R. (eds) Airborne Wind EnEn-ergy. Green Energy and Technology. Springer, Singapore, pp. 643ś662 (2018). https://doi.org/10.1007/978-981-10-1947-0_26
[2] awebox. Modelling and optimal control of multiple-kite systems for airborne wind energy (2019). https://github.com/awebox/awebox
