Development of an Actuator Line Model for Simulation of Floating Offshore Wind Turbines

2021 ◽  
Author(s):  
Alireza Arabgolarcheh ◽  
Ernesto Benini ◽  
Morteza Anbarsooz
Keyword(s):  
Wind Turbines ◽  
Computational Cost ◽  
Considerable Effect ◽  
Initial Position ◽  
Computational Method ◽  
Offshore Wind ◽  
Line Model ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Actuator Line Model

Abstract This study focuses on developing and applying an actuator line model (ALM) to predict the wake behind floating offshore wind turbines (FOWTs). A computational method is presented which implements an ALM, able to handle 6 Degree-of-Freedom (DOF) motion dynamics, coupled with a CFD solver. Computational grides used are cubic and do not require a boundary layer mesh. Results show that just about 300k grids are necessary for performance assessment of the NREL Phase VI case. Therefore, the proposed method leads to significantly lower computational cost and easier preprocessing compared to high-order methods used for solving RANS. On the other hand, coupled aerodynamic and motion analyses showed that pitch and surge motions have the most considerable influence on turbine performance due to their inherent effect on 3D local wind inclination in the relative frame. The peak power happened when the platform is in its initial position, where the platform motion velocity is maximum. Finally, it is shown that the wind turbine movement has a considerable effect on its wake characteristics. The gap distances between wake rings can also change wake interactions, and, for the case with platform pitch motion, the condition of the wake is even more complicated as such distance is not the same in all azimuthal sectors. The results show that the applied ALM method is beneficial for simulating the wake behind offshore wind turbines and the complex phenomena in the wake due to platform oscillation.

scholarly journals Hydro-Servo-Aero-Elastic Analysis of Floating Offshore Wind Turbines

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 200
Author(s):  
Dimitris I. Manolas ◽  
Vasilis A. Riziotis ◽  
George P. Papadakis ◽  
Spyros G. Voutsinas
Keyword(s):  
Structural Dynamics ◽  
Wind Turbines ◽  
Computational Cost ◽  
Physical Models ◽  
Offshore Wind ◽  
Mooring Lines ◽  
Rotor Aerodynamics ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Free Wake

A fully coupled hydro-servo-aero-elastic simulator for the analysis of floating offshore wind turbines (FOWTs) is presented. All physical aspects are addressed, and the corresponding equations are concurrently solved within the same computational framework, taking into account the wind and wave excitations, the aerodynamic response of the rotor, the hydrodynamic response of the floater, the structural dynamics of the turbine-floater-mooring lines assembly and finally the control system of the wind turbine. The components of the complex multi-physics system of a FOWT interact with each other in an implicitly coupled manner leading to a holistic type of modeling. Different modeling options, of varying fidelity and computational cost, are made available with respect to rotor aerodynamics, hydrodynamic loading of the floater and mooring system dynamics that allow for timely routine certification simulations, but also for computationally intense simulations of less conventional operating states. Structural dynamics is based on nonlinear multibody analysis that allows reproducing the large rigid body motions undergone by the FOWT, as well as large deflections and rotations of the highly flexible blades. The paper includes the description of the main physical models, of the interaction and solution strategy and representative results. Verification is carried out by comparing with other state-of-art tools that participated in the Offshore Code Comparison Collaboration Continuation (OC4) IEA Annex, while the advanced simulation capabilities are demonstrated in the case of half-wake interaction of floating wind turbines by employing the free-wake aerodynamic method.

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 Impact of Typhoons on Floating Offshore Wind Turbines: A Case Study of Typhoon Mangkhut

2021 ◽  
Vol 9 (5) ◽  
pp. 543
Author(s):  
Jiawen Li ◽  
Jingyu Bian ◽  
Yuxiang Ma ◽  
Yichen Jiang
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Safety Evaluation ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Motion Response ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Coupling Motion

A typhoon is a restrictive factor in the development of floating wind power in China. However, the influences of multistage typhoon wind and waves on offshore wind turbines have not yet been studied. Based on Typhoon Mangkhut, in this study, the characteristics of the motion response and structural loads of an offshore wind turbine are investigated during the travel process. For this purpose, a framework is established and verified for investigating the typhoon-induced effects of offshore wind turbines, including a multistage typhoon wave field and a coupled dynamic model of offshore wind turbines. On this basis, the motion response and structural loads of different stages are calculated and analyzed systematically. The results show that the maximum response does not exactly correspond to the maximum wave or wind stage. Considering only the maximum wave height or wind speed may underestimate the motion response during the traveling process of the typhoon, which has problems in guiding the anti-typhoon design of offshore wind turbines. In addition, the coupling motion between the floating foundation and turbine should be considered in the safety evaluation of the floating offshore wind turbine under typhoon conditions.

scholarly journals Performance Analysis on the Use of Oscillating Water Column in Barge-Based Floating Offshore Wind Turbines

Mathematics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 475
Author(s):  
Payam Aboutalebi ◽  
Fares M’zoughi ◽  
Izaskun Garrido ◽  
Aitor J. Garrido
Keyword(s):  
Wind Turbines ◽  
Positive Impact ◽  
Offshore Wind ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Water Columns ◽  
Numerical Tools ◽  
Oscillating Water Columns ◽  
The Given ◽  
The Waves

Undesired motions in Floating Offshore Wind Turbines (FOWT) lead to reduction of system efficiency, the system’s lifespan, wind and wave energy mitigation and increment of stress on the system and maintenance costs. In this article, a new barge platform structure for a FOWT has been proposed with the objective of reducing these undesired platform motions. The newly proposed barge structure aims to reduce the tower displacements and platform’s oscillations, particularly in rotational movements. This is achieved by installing Oscillating Water Columns (OWC) within the barge to oppose the oscillatory motion of the waves. Response Amplitude Operator (RAO) is used to predict the motions of the system exposed to different wave frequencies. From the RAOs analysis, the system’s performance has been evaluated for representative regular wave periods. Simulations using numerical tools show the positive impact of the added OWCs on the system’s stability. The results prove that the proposed platform presents better performance by decreasing the oscillations for the given range of wave frequencies, compared to the traditional barge platform.

Open-Loop Control Co-Design of Floating Offshore Wind Turbines Using Linear Parameter-Varying Models

2021 ◽  
Author(s):  
Athul K. Sundarrajan ◽  
Yong Hoon Lee ◽  
James T. Allison ◽  
Daniel R. Herber
Keyword(s):  
Wind Turbines ◽  
Open Loop ◽  
Offshore Wind ◽  
Linear Parameter ◽  
Design Decisions ◽  
Linear Parameter Varying ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Parameter Varying ◽  
And Control

Abstract This paper discusses a framework to design elements of the plant and control systems for floating offshore wind turbines (FOWTs) in an integrated manner using linear parameter-varying models. Multiple linearized models derived from high-fidelity software are used to model the system in different operating regions characterized by the incoming wind speed. The combined model is then used to generate open-loop optimal control trajectories as part of a nested control co-design strategy that explores the system’s stability and power production in the context of crucial plant and control design decisions. A cost model is developed for the FOWT system, and the effect of plant decisions and subsequent power and stability response of the FOWT is quantified in terms of the levelized cost of energy (LCOE) for that system. The results show that the stability constraints and the plant design decisions affect the turbine’s power and, subsequently, LCOE of the system. The results indicate that a lighter plant in terms of mass can produce the same power for a lower LCOE while still satisfying the constraints.

Software-in-the-Loop Combined Machine Learning for Dynamic Responses Analysis of Floating Offshore Wind Turbines

2021 ◽  
Author(s):  
Peng Chen ◽  
Changhong Hu ◽  
Zhiqiang Hu
Keyword(s):  
Machine Learning ◽  
Experimental Data ◽  
Wind Turbines ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Learning Technology ◽  
Mean Values ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Brute Force Method

Abstract Artificial intelligence (AI) brings a new solution to overcome the challenges of Floating offshore wind turbines (FOWTs) to better predict the dynamic responses with intelligent strategies. A new AI-based software-in-the-loop method, named SADA is introduced in this paper for the prediction of dynamic responses of FOWTs, which is proposed based on an in-house programme DARwind. DARwind is a coupled aero-hydro-servo-elastic in-house program for FOWTs, and a reinforcement learning method with exhaust algorithm and deep deterministic policy gradient (DDPG) are embedded in DARwind as an AI module. Firstly, the methodology is introduced with the selection of Key Disciplinary Parameters (KDPs). Secondly, Brute-force Method and DDPG algorithms are adopted to changes the KDPs’ values according to the feedback of 6DOF motions of Hywind Spar-type platform through comparing the DARwind simulation results and those of basin experimental data. Therefore, many other dynamic responses that cannot be measured in basin experiment can be predicted in good accuracy with SADA method. Finally, the case study of SADA method was conducted and the results demonstrated that the mean values of the platform’s motions can be predicted with higher accuracy. This proposed SADA method takes advantage of numerical-experimental method, basin experimental data and the machine learning technology, which brings a new and promising solution for overcoming the handicap impeding direct use of conventional basin experimental way to analyze FOWT’s dynamic responses during the design phase.

Fault Tree Analysis of floating offshore wind turbines

2019 ◽  
Vol 133 ◽  
pp. 1455-1467 ◽  
Author(s):  
Jichuan Kang ◽  
Liping Sun ◽  
C. Guedes Soares
Keyword(s):  
Wind Turbines ◽  
Fault Tree ◽  
Fault Tree Analysis ◽  
Offshore Wind ◽  
Tree Analysis ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines
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