An open-source comprehensive numerical model for dynamic response and loads analysis of floating offshore wind turbines

Energy ◽  
2018 ◽  
Vol 154 ◽  
pp. 442-454 ◽  
Author(s):  
M. Barooni ◽  
N. Ale Ali ◽  
T. Ashuri
Keyword(s):  
Numerical Model ◽  
Dynamic Response ◽  
Open Source ◽  
Wind Turbines ◽  
Offshore Wind ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Loads Analysis

scholarly journals Simulation-Length Requirements in the Loads Analysis of Offshore Floating Wind Turbines

2013 ◽  
Author(s):  
Lorenz Haid ◽  
Gordon Stewart ◽  
Jason Jonkman ◽  
Amy Robertson ◽  
Matthew Lackner ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Ocean Waves ◽  
Offshore Wind ◽  
International Electrotechnical Commission ◽  
Wind System ◽  
Offshore Wind Turbines ◽  
Design Standard ◽  
Floating Offshore Wind Turbines ◽  
Loads Analysis ◽  
Design Requirements

The design standard typically used for offshore wind system development, the International Electrotechnical Commission (IEC) 61400-3 fixed-bottom offshore design standard, explicitly states that “the design requirements specified in this standard are not necessarily sufficient to ensure the engineering integrity of floating offshore wind turbines” [1]. One major concern is the prescribed simulation length time of 10 minutes for a loads-analysis procedure, which is also typically used for land-based turbines. Because floating platforms have lower natural frequencies, which lead to fewer load cycles over a given period of time, and ocean waves have lower characteristic frequencies than wind turbulence, the 10-min simulation length recommended by the current standards for land-based and offshore turbines may be too short for combined wind and wave loading of floating offshore wind turbines (FOWTs). Therefore, the goal of this paper is to examine the appropriate length of a FOWT simulation — a fundamental question that needs to be answered to develop design requirements. To examine this issue, we performed a loads analysis of an example FOWT with varying simulation lengths, using FAST, the National Renewable Energy Laboratory’s (NREL’s) nonlinear aero-hydro-servo-elastic simulation tool. The offshore wind system used was the OC3-Hywind spar buoy, which was developed for use in the International Energy Agency (IEA) Offshore Code Comparison Collaborative (OC3) project, and supports NREL’s offshore 5-MW baseline turbine. Realistic metocean data from the National Oceanic and Atmospheric Administration (NOAA) and repeated periodic wind files were used to excite the structure. The results of the analysis clearly show that loads do not increase for longer simulations. In regard to fatigue, a sensitivity analysis shows that the procedure used for counting half cycles is more important than the simulation length itself. Based on these results, neither the simulation length nor the periodic wind files affect response statistics and loads for FOWTs (at least for the spar studied here); a result in contrast to the offshore oil and gas (O&G) industry, where running simulations of at least 3 hours in length is common practice.

scholarly journals A Reference Open-Source Controller for Fixed and Floating Offshore Wind Turbines

2021 ◽  
Author(s):  
Nikhar Abbas ◽  
Daniel Zalkind ◽  
Lucy Pao ◽  
Alan Wright
Keyword(s):  
Wind Turbine ◽  
Open Source ◽  
Wind Turbines ◽  
Torque Control ◽  
Offshore Wind ◽  
Speed Ratio ◽  
Offshore Wind Turbine ◽  
Offshore Wind Turbines ◽  
Industry Standards ◽  
Floating Offshore Wind Turbines

Abstract. This paper describes the development of a new reference controller framework for fixed and floating offshore wind turbines that greatly facilitates controller tuning and represents standard industry practices. The reference wind turbine controllers that are most commonly cited in the literature have been developed to work with specific reference wind turbines. Although these controllers have provided standard control functionalities, they are often not easy to modify for use on other turbines, so it has been challenging for researchers to run representative, fully dynamic simulations of other wind turbine designs. The Reference Open-Source Controller (ROSCO) has been developed to provide a modular reference wind turbine controller that represents industry standards and performs comparably to or better than existing reference controllers. The formulation of the ROSCO controller logic and tuning processes is presented in this paper. Control capabilities such as tip-speed ratio tracking generator torque control, minimum pitch saturation, wind speed estimation, and a smoothing algorithm at near-rated operation are included to provide a controller that is comparable to industry standards. A floating offshore wind turbine feedback module is also included to facilitate growing research in the floating offshore arena. All the standard controller implementations and control modules are automatically tuned such that a non-controls engineer or automated optimization routine can easily improve the controller performance. This article provides the framework and theoretical basis for the ROSCO controller modules and generic tuning processes. Simulations of the National Renewable Energy Laboratory (NREL) 5-MW reference wind turbine and International Energy Agency 15-MW reference turbine on the University of Maine semisubmersible platform are analyzed to demonstrate the controller's performance in both fixed and floating configurations, respectively. The simulation results demonstrate ROSCO's peak shaving routine to reduce maximum rotor thrusts by nearly 14 % compared to the NREL 5-MW reference wind turbine controller on the land-based turbine and to reduce maximum platform pitch angles by slightly more than 35 % when using the platform feedback routine instead of a more traditional low-bandwidth controller.

scholarly journals Numerical and Physical Modeling of a Tension-Leg Platform for Offshore Wind Turbines

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3554
Author(s):  
Daniel Walia ◽  
Paul Schünemann ◽  
Hauke Hartmann ◽  
Frank Adam ◽  
Jochen Großmann
Keyword(s):  
Numerical Model ◽  
Wind Turbines ◽  
Model Testing ◽  
Offshore Wind ◽  
Scaled Model ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Cost Efficient ◽  
Decay Tests ◽  
Floating Platforms

In order to tap the world wide offshore wind resources above deep waters, cost efficient floating platforms are inevitable. Tension-Leg Platforms (TLPs) could enable that crucial cost reduction in floating wind due to their smaller size and lighter weight compared to spars and semi-submersibles. The continuous development of the GICON®-TLP is driven by computer-aided engineering. So-called aero-hydro-servo-elastic coupled simulations are state-of-the-art for predicting loads and simulating the global system behavior for floating offshore wind turbines. Considering the complexity of such simulations, it is good scientific praxis to validate these numerical calculations by use of scaled model testing. This paper addresses the setup of the scaled model testing as carried out at the offshore basin of the École Centrale de Nantes, as well as the numerical model for the GICON®-TLP. The results of dedicated decay tests of the scaled model are used to validate the computational model at the first stage and to determine the natural frequencies of the system. Besides different challenges to the scaled model during the survey, it was possible to take these difficulties into account when updating the numerical model. The results show good agreements for the tank tests and the numerical model.

Full-System Linearization for Floating Offshore Wind Turbines in OpenFAST

2018 ◽  
Author(s):  
Jason M. Jonkman ◽  
Alan D. Wright ◽  
Greg J. Hayman ◽  
Amy N. Robertson
Keyword(s):  
Wind Turbines ◽  
Wind Engineering ◽  
Offshore Wind ◽  
Design Standards ◽  
Offshore Wind Turbines ◽  
Engineering Software ◽  
Floating Offshore Wind Turbines ◽  
Loads Analysis ◽  
System Equations ◽  
System Properties

The wind engineering community relies on multiphysics engineering software to run nonlinear time-domain simulations (e.g., for design-standards-based loads analysis). Although most physics involved in wind energy are nonlinear, linearization of the underlying nonlinear system equations is often advantageous to understand the system properties and exploit well-established methods and tools for analyzing linear systems. This paper presents the development of the new linearization functionality of the open-source engineering tool OpenFAST for floating offshore wind turbines, as well as the concepts and mathematical background needed to understand and apply it.

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.

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