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The Science of Making Torque from Wind (TORQUE 2018)

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Room: BL.27.02
Chaired by: Po Wen Cheng | USTUTT
Topic: CM. Control and Monitoring
Form of presentation: Oral
Duration: 110 minutes

Authors:
Davide Astolfi, Francesco Castellani, Ludovico Terzi

Abstract:
The target of improving efficiency of wind kinetic energy extraction has stimulated a certain attention to wind turbine retrofitting. This kind of interventions has material and labour costs and producible energy is lost during installation. Therefore, a precise estimation of performance improvement is fundamental. In this work, a SCADA-based method is formulated for estimating the improvement in energy production of wind turbines, having 2.3 MW of rated power each, sited in Italy in a very complex terrain. The blades of some wind turbines in the farm have been optimized by installing vortex generators and passive flow control devices. One key point is that the nacelle transfer function hasn’t been updated by the manufacturer after the retrofitting: therefore, the nacelle wind speed measurements are not reliable. In this work, an Artificial Neural Network model is employed: the output is the power of the retrofitted wind turbine and the inputs are the powers of some reference wind turbines. The production increase is estimated by observing how the difference between simulated and measured power output changes after the installation of the aerodynamic upgrade. The average improvement is estimated being of the order of 4% of the energy produced below rated power.

Authors:
Zili Zhang, Christian Høeg

Abstract:
This paper investigates the use of two different liquid column dampers for vibration control of spar-type floating offshore wind turbines (FOWTs). A 16-degree-of-freedom (16-DOF) aero-hydro-servo-elastic model for the FOWT is first established using multi-body based formulation and the Euler-Lagrangian equation, taking into consideration the full coupling of the blade-drivetrain-tower-spar vibrations, a collective pitch controller and a generator controller. It is found from the simulation results that due to the coupling to the spar rigid-body motion, the eigenfrequency of the tower vibration is significantly changed, which needs to be accounted for when tuning the liquid dampers. Tuned liquid column damper (TLCD) is investigated for controlling the lightly damped (due to low aerodynamic damping) tower side-side vibration and blade edgewise vibrations. Further, a newly proposed liquid column damper, the circular liquid column damper (CLCD) is also investigated for blade edgewise vibration control. The large centrifugal acceleration from the rotating blade makes it possible to use liquid column dampers with rather small masses for effectively suppressing edgewise vibrations. By properly tuning the dampers, both types of liquid column dampers are effective in mitigating tower and blade vibrations.  Performances of the dampers are compared in terms of the control efficiency and practical considerations.

Authors:
Bastian Ritter, Edwin Camilo Mora Gil, Thorsten Schlicht, Axel Schild, Ulrich Konigorski

Abstract:
This contribution investigates different adaptive Kalman filters with respect to their usability for wind turbine application. Since advanced model-based control schemes arise as promising alternative for standard industrial controllers, the necessity for robust and adaptive state estimation techniques has simultaneously emerged as an important topic. The simulation study proves that adaptive filters are beneficial since they solve two typical problems involved with static Kalman filter design: First, filter parameter adaptation enables to compensate incorrect assumptions of noise statistics online. Secondly, adaptation rules prevent poor filterperformance from conservative static design for systems with time-varying statistical properties.

Authors:
Róbert Ungurán

Abstract:
The objective of this paper is to evaluate how the feedforward controller performance is affected when the telescope parameters are fixed compared to the use of wind speed dependent dynamic parameters. First the telescope parameters for both cases are determined, then the robust feedback controllers are extended with and inverse based feedforward individual pitch and trailing edge flap controller to alleviate the 1P and 2P loads of the flapwise blade root bending moments.The results are promissing with respect to the applicability of the blade-mounted LiDAR. Since dynamic parametrisation of the telescope,around and above rated wind speed, provides only a marginal improvement compared to fixed parameter case.

Authors:
Lorenzo Colone

Abstract:
The research aims at defining a performance measure for inportant mechanical failures starting from a normal behaviour modelling of damage sensitive features. The feature selected is the main bearing temperature. The reliability of the warning system is then quantified based on a cost-benefit analysis, where a cost is associated to false alarms against the benefit of the early prediction of a failure. A case study of 3 main bearing failures from an offshore wind farm is analysed.

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