1,720,952 research outputs found
Flight path planning in a turbulent wind environment
No full textTo achieve a high conversion efficiency and at the same time robust control of a pumping kite power system it is crucial to optimize the three-dimensional flight path of the tethered wing. This chapter extends a dynamic system model to account for a realistic, turbulent wind environment and adds a flight path planner using a sequence of attractor points and turn actions. Path coordinates are calculated with explicit geometric formulas. To optimize the power output the path is adapted to the average wind speed and the vertical wind profile, using a small set of parameters. The planner employs a finite state machine with switch conditions that are highly robust towards sensor errors. The results indicate, that the decline of the average power output of pumping kite power systems at high wind speeds can be mitigated. In addition it is shown, that reeling out towards the zenith after flying figure eight flight maneuvers significantly reduces the traction forces during reel-in and thus increases the total efficiency.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Delft University Wind energy research instituteWind Energ
Particle System Modelling and Dynamic Simulation of a Tethered Rigid Wing Kite for Power Generation
No full textKite Power research group at TU Delft developed the KiteSim framework for dynamic simulation of crosswind kite power systems. Currently, KiteSim has the capability to simulate leading edge inflatable kites. The use of rigid wing kites in crosswind kite power systems is becoming widespread. Accordingly, KiteSim framework is planned to be augmented to simulate the rigid wing kite power systems as well. Therefore, objective of this thesis is set to enhance the KiteSim framework in order to include the capability of the dynamic simulation of a rigid wing pumping crosswind kite power system by developing a particle system model to represent the tethered rigid wing. The particle system model of rigid wing consists of 6 point masses and 13 spring-damper elements. Positions and masses of the discrete particles are calculated in order to represent the rigid wing properties accurately. The spring-damper elements are interconnecting the particles. Lifting line theory and Kirke’s post stall correlation methods are used to create the full angle of attack aerodynamic model for wings and tails. Available atmospheric, tether and winch models of the KiteSim framework are also used for rigid wing dynamic simulations. Equation of the motion of the particle system model is formulated as an implicit problem, which is simulated by implicit Runge-Kutta method of fifth-order. Validation simulations are conducted with the particle system model of NASA SGS 1-36 flight test sailplane. Validation cases show satisfactory results with the flight test data. For the remaining simulations, AP2 PowerPlane of Ampyx Power is modelled as particle system and manually flown in KiteSim. Mass properties of the model is found to be highly accurate throughout the simulations. Power generation capabilities of the model is checked by flying figure-of-eight trajectories. Reel-out phases are investigated, a peak mechanical power of 45 kW and a mean power of 10 kW are obtained. Further comparison of the reel-out dynamic simulations with the quasi-steady theoretical calculations is done. Moreover, gliding and stalling manoeuvres are simulated for a plausibility check study. The developed particle system model for rigid wings shows satisfactory results and a potential for further development.Aerospace EngineeringAerodynamics, Wind Energy & PropulsionFlight Performance and Propulsio
A Methodology for the Design of Kite-Power Control Systems
No full textWind EnergyDelft University Wind energy research institut
Improving winch control performance in Kite Power Systems using gain scheduling and a compliant element
No full textRising demands in energy consumption necessitate the development of low-cost renewable power generation. A Kite Power Sytem (KPS) is a novel approach to harvest wind energy with kites at higher altitudes than is possible with conventional wind turbines, at a lower cost. In this thesis, an approach to improve the winch controller of a KPS will be proposed in order to increase the power output. Measurements of the test system revealed an especially poor performance during the reel out phase, where the tether force was constrained to a maximum. It was found that a propagation delay is present on the system input. A force tracking controller for the reel out phase therefore needs to be developed, which accounts for the system’s propagation delays. A nonlinear KPS model that can be used in control algorithm design was presented. To control the nonlinear system across its full operating region, a gain scheduled feedback controller was proposed. It was found that the stability of the modeled original system was compromised when the system delay is high enough. By extending the system with a compliant element, a larger delay can be allowed before instability occurs. Within the boundary conditions of the nonlinear KPS model, by applying gain scheduled feedback control with integral action and extending the system with a compliant element, the winch controller can asymptotically track a force reference across its operating region in case of system delays. Given that the correct force reference is supplied, this will increase the power output of the KPS.Embedded SystemsDCSCElectrical Engineering, Mathematics and Computer Scienc
Design of a Real-Time Micro-Winch Controller for Kite-Power Applications
No full textDesign of a real time steering and depowering controller for kite power applications. The controller includes kite tapes tension estimation, tension limitation, and current limitation.Embedded SystemsEmbedded SystemsElectrical Engineering, Mathematics and Computer Scienc
Feed-Forward Control of Kite Power Systems
No full textKite power technology is a novel solution to harvest wind energy from altitudes that can not be reached by conventional wind turbines. The use of a lightweight but strong tether in place of an expensive tower provides an additional cost advantage, next to the higher capacity factor. This paper describes a method to estimate the wind velocity at the kite using measurement data at the kite and at the ground. Focussing on a kite power system, which is converting the traction power of a kite in a pumping mode of operation, a reel-out speed predictor is presented for use in feed-forward control of the tether reel-out speed of the winch. The results show, that the developed feedforward controller improves the force control accuracy by a factor of two compared to the previously used feedback controller. This allows to use a higher set force during the reel-out phase which in turn increases the average power output by more than 4 %. Due to its straightforward implementation and low computational requirements feedforward control is considered a promising technique for the reliable and efficient operation of traction-based kite power systems.Aerodynamics, Wind Energy & PropulsionAerospace Engineerin
Downscaling of Airborne Wind Energy Systems
No full textAirborne wind energy systems provide a novel solution to harvest wind energy from altitudes that can not be reached by wind turbines with a similar nominal generator power. The use of a lightweight but strong tether in place of an expensive tower provides an additional cost advantage, next to the higher capacity factor and much lower total mass. This paper investigates the scaling eects of airborne wind energy systems. The energy yield of airborne wind energy systems, that work in pumping mode of operation is at least ten times higher than the energy yield of conventional solar systems. For airborne wind energy systems the yield is defined per square meter wing area. In this paper the dependency of the energy yield on the nominal generator power for systems in the range of 1 kW to 1 MW is investigated. For the onshore location Cabauw, The Netherlands, it is shown, that a generator of just 1.4 kW nominal power and a total system mass of less then 30 kg has the theoretical potential to harvest energy at only twice the price per kWh of large scale airborne wind energy systems. This would make airborne wind energy systems a very attractive choice for small scale remote and mobile applications as soon as the remaining challenges for commercialization are solved
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