Linear coupled model for floating wind turbine control

2018 ◽  
Vol 42 (2) ◽  
pp. 115-127 ◽  
Author(s):  
Alessandro Fontanella ◽  
Ilmas Bayati ◽  
Marco Belloli
Keyword(s):  
Degrees Of Freedom ◽  
Coupled Model ◽  
Control Design ◽  
Offshore Wind ◽  
Order Model ◽  
Reduced Order ◽  
Offshore Wind Turbines ◽  
Wind Turbine Control ◽  
Floating Offshore Wind Turbines ◽  
Three Degrees Of Freedom

This work deals with an analytical linear coupled model describing the integrated aero-hydrodynamics of floating offshore wind turbines. Three degrees of freedom (platform surge, platform pitch and rotor azimuth) were considered with the goal of building a reduced-order model suitable for being integrated in control design algorithms as well as to be used for a straightforward evaluation and comprehension of the global system dynamics.

scholarly journals Advances on Reduced-Order Modeling of Floating Offshore Wind Turbines

2021 ◽  
Author(s):  
Frank Lemmer ◽  
Wei Yu ◽  
Heiner Steinacker ◽  
Danai Skandali ◽  
Steffen Raach
Keyword(s):  
Wind Turbines ◽  
State Feedback ◽  
The State ◽  
Offshore Wind ◽  
Weight Functions ◽  
Elastic Model ◽  
Reduced Order ◽  
Offshore Wind Turbines ◽  
Modeling Uncertainties ◽  
Floating Offshore Wind Turbines

Abstract Aero-hydro-servo-elastic modeling of Floating Offshore Wind Turbines (FOWTs) is a key component in the design process of various components of the system. Different approaches to order reduction have been investigated with the aim of improving structural design, manufacturing, transport and installation, but also the dynamic behavior, which is largely affected by the blade pitch controller. The present work builds on previous works on the SLOW (Simplified Low-Order Wind Turbine) code, which has already been used for the above purposes, including controller design. While the previous rigid rotor model gives good controllers in most cases, we investigate in the present work the question if aero-elastic effects in the design model can improve advanced controllers. The SLOW model is extended for the flap-wise bending and coupled to NREL’s AeroDyn, linearized and verified with the OlavOlsen OO-Star Wind Floater Semi 10MW public FOWT model. The results show that the nonlinear and linear reduced-order SLOW models agree well against OpenFAST. The state-feedback Linear Quadratic Regulator (LQR) applied with the same weight functions to both models, the old actuator disk, and the new aero-elastic model shows that the LQR becomes more sensitive to nonlinear excitation and that the state feedback matrix is significantly different, which has an effect on the performance and potentially also on the robustness. Thus modeling uncertainties might even be more critical for the LQR of the higher-fidelity model.

Reduced-Order Model of a Mistuned Multi-Stage Bladed Rotor

2007 ◽  
Author(s):  
Alok Sinha
Keyword(s):  
Degrees Of Freedom ◽  
Maximum Amplitude ◽  
Reduced Order Model ◽  
Order Model ◽  
Mass Model ◽  
Reduced Order ◽  
Multi Stage ◽  
Bladed Rotor ◽  
The Impact ◽  
Three Degrees Of Freedom

This paper deals with a reduced-order model of a multi-stage rotor in which each stage has a different number of blades. In particular, it is shown that a reduced-order model can be developed on the basis of tuned modes of certain bladed disks. The validity of this algorithm is shown for a spring-mass model with three degrees of freedom per sector. In addition, the statistical distributions of the peak maximum amplitude are generated via Monte Carlo simulations, and the impact of mistuning is examined for a two-stage rotor.

Control of Floating Offshore Wind Turbines: Reduced-Order Modeling and Real-Time Implementation for Wind Tunnel Tests

2018 ◽  
Author(s):  
Alessandro Fontanella ◽  
Ilmas Bayati ◽  
Marco Belloli
Keyword(s):  
Wind Tunnel ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Offshore Wind ◽  
Scale Model ◽  
System Response ◽  
Wind Tunnel Tests ◽  
Reduced Order ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

The present work deals with the implementation of a variable-speed variable-pitch control strategy on a wind turbine scale model for hybrid/HIL wind tunnel tests on floating offshore wind turbines. The effects that scaling issues, due to low-Reynolds aerodynamics and rotor structural properties, have in combination with the HIL technique developed by the authors are studied through a dedicated reduced-order linear coupled model. The model is used to tune the original pitch controller gains so to be able to reproduce the system response of the full-scale floating wind turbine during HIL tests.

On the Comparison of the Dynamic Response of an Offshore Floating VAWT System When Adopting Two Different Mooring System Model of Dynamics: Quasi-Static vs Lumped Mass Approach

2017 ◽  
Author(s):  
Debora Cevasco ◽  
Maurizio Collu ◽  
Matthew Hall ◽  
Cesare M. Rizzo
Keyword(s):  
Dynamic Response ◽  
Coupled Model ◽  
Wind Farms ◽  
Offshore Wind ◽  
Mooring Line ◽  
Lumped Mass ◽  
Offshore Wind Turbines ◽  
Research Activities ◽  
Floating Offshore Wind Turbines ◽  
Mooring Dynamics

The interest in floating offshore wind turbines (FOWT) has been growing substantially over the last decade and, after a number of prototypes deployed [1], the first offshore floating wind farms have been approved and are being developed. While a number of international research activities have been conducted on the dynamics of offshore floating HAWT systems (e.g. OC3-Phase IV2, OC4-Phase II3), relatively few studies have been conducted on floating VAWT systems, despite their potential advantages [2]. Due to the substantial differences between HAWT and VAWT aerodynamics, the analyses on floating HAWT cannot be extended to floating VAWT systems. The main aim of the present work is to compare the dynamic response of the FOWT system adopting two different mooring dynamics approaches. Two version of the in-house aero-hydro-mooring coupled model of dynamics for VAWT “FloVAWT” [3] are used: one which adopts a mooring quasi-static model, and solves the equations using an energetic approach [4], and a modified version of FloVAWT, which uses instead the lumped-mass mooring line model “MoorDyn” [5]. The floating VAWT system considered is based on a 5MW Darrieus type rotor supported by the OC4-Phase II3 semi-submersible. The results for the considered metocean conditions show that MoorDyn approach estimate larger translational displacements of the platform, compared to the quasi-static rigid approach previously implemented in FloVAWT. As expected, the magnitudes of the forces along the lines are lower, being part of the energy employed for the elastic deformation of the cables. A systematic comparison of the differences between the two approaches is presented.

scholarly journals The TripleSpar Campaign: Validation of a Reduced-Order Simulation Model for Floating Wind Turbines

2018 ◽  
Author(s):  
Frank Lemmer (né Sandner) ◽  
Wei Yu ◽  
Po Wen Cheng ◽  
Antonio Pegalajar-Jurado ◽  
Michael Borg ◽  
...  
Keyword(s):  
Simulation Model ◽  
Wind Turbines ◽  
Degrees Of Freedom ◽  
Coupled System ◽  
Offshore Wind ◽  
Drag Coefficients ◽  
Reduced Order ◽  
Irregular Wave ◽  
Floating Offshore Wind Turbines ◽  
Decay Tests

Different research groups have recently tested scaled floating offshore wind turbines including blade pitch control. A test conducted by the University of Stuttgart (Germany), DTU (Denmark) and CENER (Spain) at the Danish Hydraulic Institute (DHI) in 2016 successfully demonstrated a real-time blade pitch controller on the public 10MW TripleSpar semi-submersible concept at a scale of 1/60. In the presented work a reduced-order simulation model including control is compared against the model tests. The model has only five degrees of freedom and is formulated either in the time-domain or in the frequency-domain. In a first step the Morison drag coefficients are identified from decay tests as well as irregular wave cases. The identified drag coefficients depend clearly on the sea state, with the highest ones for the decay tests and small sea states. This is an important finding, for example for the design of a robust controller, which depends on the system damping. It is shown that the simplified model can well represent the dominant physical effects of the coupled system with a substantially reduced simulation time, compared to state-of-the-art models.

scholarly journals Iterative Frequency-Domain Response of Floating Offshore Wind Turbines with Parametric Drag

2018 ◽  
Vol 6 (4) ◽  
pp. 118 ◽  
Author(s):  
Frank Lemmer ◽  
Wei Yu ◽  
Po Cheng
Keyword(s):  
System Dynamics ◽  
Frequency Domain ◽  
Wind Turbines ◽  
Domain Model ◽  
Offshore Wind ◽  
Viscous Drag ◽  
Drag Coefficients ◽  
Reduced Order ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

Methods for coupled aero-hydro-servo-elastic time-domain simulations of Floating Offshore Wind Turbines (FOWTs) have been successfully developed. One of the present challenges is a realistic approximation of the viscous drag of the wetted members of the floating platform. This paper presents a method for an iterative response calculation with a reduced-order frequency-domain model. It has heave plate drag coefficients, which are parameterized functions of literature data. The reduced-order model does not represent more than the most relevant effects on the FOWT system dynamics. It includes first-order and second-order wave forces, coupled with the wind turbine structural dynamics, aerodynamics and control system dynamics. So far, the viscous drag coefficients are usually defined as constants, independent of the load cases. With the computationally efficient frequency-domain model, it is possible to iterate the drag, such that it fits to the obtained amplitudes of oscillation of the different members. The results show that the drag coefficients vary significantly across operational load conditions. The viscous drag coefficients converge quickly and the method is applicable for concept-level design studies of FOWTs with load case-dependent drag.

Pitch Angle Control of Floating Offshore Wind Turbines by H∞ Control

2014 ◽  
Vol 134 (8) ◽  
pp. 1096-1103 ◽  
Author(s):  
Sho Tsujimoto ◽  
Ségolène Dessort ◽  
Naoyuki Hara ◽  
Keiji Konishi
Keyword(s):  
Wind Turbines ◽  
Pitch Angle ◽  
Offshore Wind ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

scholarly journals Effect of Roughness of Mussels on Cylinder Forces from a Realistic Shape Modelling

2021 ◽  
Vol 9 (6) ◽  
pp. 598
Author(s):  
Antoine Marty ◽  
Franck Schoefs ◽  
Thomas Soulard ◽  
Christian Berhault ◽  
Jean-Valery Facq ◽  
...  
Keyword(s):  
Marine Species ◽  
Offshore Structures ◽  
Offshore Wind ◽  
Mooring Lines ◽  
Shape Modelling ◽  
Offshore Wind Turbines ◽  
Specific Effects ◽  
Hydrodynamic Loading ◽  
Floating Offshore Wind Turbines ◽  
Realistic Shape

After a few weeks, underwater components of offshore structures are colonized by marine species and after few years this marine growth can be significant. It has been shown that it affects the hydrodynamic loading of cylinder components such as legs and braces for jackets, risers and mooring lines for floating units. Over a decade, the development of Floating Offshore Wind Turbines highlighted specific effects due to the smaller size of their components. The effect of the roughness of hard marine growth on cylinders with smaller diameter increased and the shape should be representative of a real pattern. This paper first describes the two realistic shapes of a mature colonization by mussels and then presents the tests of these roughnesses in a hydrodynamic tank where three conditions are analyzed: current, wave and current with wave. Results are compared to the literature with a similar roughness and other shapes. The results highlight the fact that, for these realistic roughnesses, the behavior of the rough cylinders is mainly governed by the flow and not by their motions.

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