Development of Coupled Program fast-simdyn and Study of Non-Linear Hydrodynamics, Coupled With Negative Damping and Aerodynamics of Floating Offshore Wind Turbines

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Alwin Jose ◽  
Jeffrey Falzarano ◽  
Hao Wang
Keyword(s):  
Computer Program ◽  
Wind Turbines ◽  
Large Amplitude ◽  
Offshore Wind ◽  
Wave Forces ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Non Linear ◽  
Large Amplitude Motions ◽  
Negative Damping

Abstract Non-linear hydrostatic and wave forces on floating structures are very important during large amplitude waves. The computer program simdyn is a blended time domain program developed by Marine Dynamics Laboratory at TAMU and is capable of capturing the role of non-linear fluid forces. simdyn has previously been used to demonstrate that nonlinear hydrostatics have become very important in the problem of parametric excitation. In the current work simdyn is coupled with the computer program fast developed by U.S. National Renewable Energy Laboratory (NREL) for numerical simulation of floating offshore wind turbines (FOWTs). fast-simdyn is now a tool that is capable of studying large amplitude motions of FOWTs in extreme seas. fast-simdyn was then used to study the classic instability of negative damping that occurs in FOWTs that use conventional land-based control. The development of platform pitch and platform surge instability are studied in relation to different wave and wind scenarios. The intent was to do an analysis to see if the non-linear forces do play a significant role in large amplitude motions induced by negative damping. This study gives an indication of whether the development and application of higher fidelity hydrodynamic modules are justified.

A Study of Negative Damping in Floating Wind Turbines Using Coupled Program FAST-SIMDYN

2018 ◽  
Author(s):  
Alwin Jose ◽  
Jeffrey Falzarano ◽  
Hao Wang
Keyword(s):  
Computer Program ◽  
Large Amplitude ◽  
Numerical Models ◽  
Offshore Wind ◽  
Combined Loading ◽  
Offshore Wind Turbine ◽  
Scale Production ◽  
Non Linear ◽  
Large Amplitude Motions ◽  
Negative Damping

The Floating Offshore Wind Turbine (FOWT) is a fairly new concept. There are limited number of full-scale prototypes to provide real data. Therefore, most of the research today relies on numerical models. This is required, so that an adequate amount of confidence can be gained before venturing into large scale production. The major challenge ahead is proving their reliability and robustness. There needs to be supporting studies that consider most factors that can go wrong. The computer program FAST was a groundbreaking contribution from NREL in this regard. FAST is capable of doing combined loading analysis of FOWTs. The numerical model used for the hydrodynamics can, however, be improved further. Non-linear hydrostatic and wave forces on floating structures become very important during large amplitude waves. The computer program SIMDYN is a blended time domain program developed by Marine Dynamics Laboratory at TAMU and is capable of capturing the role of non-linear fluid forces. SIMDYN has previously been used to demonstrate that nonlinear hydrostatics become very important in the problem of parametric excitation. In the current work, SIMDYN is coupled with FAST. The FAST-SIMDYN is now a tool that is capable of studying large amplitude motions of FOWTs in extreme seas. FAST-SIMDYN was then used to study the classic instability of negative damping that occurs in FOWTs that use conventional land based control. The development of platform pitch and platform surge instability are studied in relation to different wave and wind scenarios. The intent was to do an analysis to see if the non-linear forces do play a significant role in large amplitude motions induced by negative damping. This study gives an indication of whether the development of an even more sophisticated hydrodynamic modules is justified.

Jump bifurcation phenomenon during varying wind speeds in floating offshore wind turbines

2022 ◽  
pp. 1-15
Author(s):  
Alwin Jose ◽  
Jeffrey M. Falzarano
Keyword(s):  
Transition Region ◽  
Wind Turbines ◽  
Large Amplitude ◽  
Offshore Wind ◽  
Nonlinear Phenomenon ◽  
Motion Response ◽  
Offshore Wind Turbines ◽  
Future Design ◽  
Wind Speeds ◽  
Floating Offshore Wind Turbines

Abstract Floating Offshore Wind Turbines (FOWTs) are susceptible to an instability which has come to be called negative damping. Conventional land based wind turbine controllers when used with FOWTs may cause large amplitude platform pitch oscillations. Most controllers have since been improved to reduce motions due to this phenomenon. In this paper, the motions induced using one of the original controllers is studied. The current study is performed using the coupled time domain program FAST-SIMDYN that was developed in Marine Dynamics Laboratory (MDL) at Texas A&M University. It is capable of studying large amplitude motions of Floating Offshore Wind Turbines. FOWTs use various controller algorithms of operation based on the available wind speed depending on various power output objectives i.e., to either maximize or level out power absorption. It is observed that the transition region for controllers is often chaotic. So most studies focus on operations away from the transition region below and above the transition wind speeds. Here we study the transition region using the theoretical insight of non-linear motion response of structures. This study reveals the presence of a very interesting and potentially hazardous nonlinear phenomenon, bifurcation. This finding could help explain the chaotic motion response that is observed in the transition region of controllers. Understanding the nature and cause of bifurcation could prove very useful for future design of FOWT controllers.

Jump Bifurcation Phenomenon During Varying Wind Speeds in Floating Offshore Wind Turbines

2020 ◽  
Author(s):  
Alwin Jose ◽  
Jeffrey Falzarano
Keyword(s):  
Transition Region ◽  
Wind Turbines ◽  
Large Amplitude ◽  
Offshore Wind ◽  
Nonlinear Phenomenon ◽  
Motion Response ◽  
Offshore Wind Turbines ◽  
Future Design ◽  
Wind Speeds ◽  
Floating Offshore Wind Turbines

Abstract Floating Offshore Wind Turbines (FOWTs) are susceptible to an instability which has come to be called “negative damping”. Conventional land based wind turbine controllers when used with FOWTs may cause large amplitude platform pitch oscillations. Most controllers have since been improved to reduce motions due to this phenomenon. In this paper, the motions induced using one of the original controllers is studied. The current study is performed using the coupled time domain program FAST-SIMDYN that was developed in Marine Dynamics Laboratory (MDL) at Texas A&M University. It is capable of studying large amplitude motions of Floating Offshore Wind Turbines. FOWTs use various controller algorithms of operation based on the available wind speed depending on various power output objectives i.e., to either maximize or level out power absorption. It is observed that the transition region for controllers is often chaotic. So most studies focus on operations away from the transition region i.e., both below and above the transition wind speeds. Here we study the transition region using the theoretical insight of non-linear motion response of structures. This study reveals the presence of a very interesting and potentially hazardous nonlinear phenomenon, bifurcation. This finding could help explain the chaotic motion response that is observed in the transition region of controllers. Understanding the nature and cause of bifurcation could prove very useful for future design of FOWT controllers.

scholarly journals Large-scale testing of a hydraulic non-linear mooring system for floating offshore wind turbines

2020 ◽  
Vol 206 ◽  
pp. 107386
Author(s):  
Magnus J. Harrold ◽  
Philipp R. Thies ◽  
David Newsam ◽  
Claudio Bittencourt Ferreira ◽  
Lars Johanning
Keyword(s):  
Wind Turbines ◽  
Large Scale ◽  
Offshore Wind ◽  
Mooring System ◽  
Offshore Wind Turbines ◽  
Large Scale Testing ◽  
Floating Offshore Wind Turbines ◽  
Non Linear

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.

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