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 Proposal and Performance Study of a Novel Mooring System with Six Mooring Lines for Spar-Type Offshore Wind Turbines

2021 ◽  
Vol 11 (24) ◽  
pp. 11665
Author(s):  
Shi Liu ◽  
Yi Yang ◽  
Chao Wang ◽  
Yuangang Tu
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Offshore Wind ◽  
Irregular Waves ◽  
Offshore Wind Turbine ◽  
Mooring System ◽  
Mooring Lines ◽  
Included Angle ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

Spar-type floating offshore wind turbines commonly vibrate excessively when under the coupling impact of wind and wave. The wind turbine vibration can be controlled by developing its mooring system. Thus, this study proposes a novel mooring system for the spar-type floating offshore wind turbine. The proposed mooring system has six mooring lines, which are divided into three groups, with two mooring lines in the same group being connected to the same fairlead. Subsequently, the effects of the included angle between the two mooring lines on the mooring-system’s performance are investigated. Then, these six mooring lines are connected to six independent fairleads for comparison. FAST is utilized to calculate wind turbine dynamic response. Wind turbine surge, pitch, and yaw movements are presented and analyzed in time and frequency domains to quantitatively evaluate the performances of the proposed mooring systems. Compared with the mooring system with six fairleads, the mooring system with three fairleads performed better. When the included angle was 40°, surge, pitch, and yaw movement amplitudes of the wind turbine reduced by 39.51%, 6.8%, and 12.34%, respectively, when under regular waves; they reduced by 56.08%, 25.00%, and 47.5%, respectively, when under irregular waves. Thus, the mooring system with three fairleads and 40° included angle is recommended.

scholarly journals The Effect of the Second-Order Wave Loads on Drift Motion of a Semi-Submersible Floating Offshore Wind Turbine

2020 ◽  
Vol 8 (11) ◽  
pp. 859
Author(s):  
Thanh-Dam Pham ◽  
Hyunkyoung Shin
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Second Order ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wave Loads ◽  
Hydrodynamic Loads ◽  
Drift Motion ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

Floating offshore wind turbines (FOWTs) have been installed in Europe and Japan with relatively modern technology. The installation of floating wind farms in deep water is recommended because the wind speed is stronger and more stable. The design of the FOWT must ensure it is able to withstand complex environmental conditions including wind, wave, current, and performance of the wind turbine. It needs simulation tools with fully integrated hydrodynamic-servo-elastic modeling capabilities for the floating offshore wind turbines. Most of the numerical simulation approaches consider only first-order hydrodynamic loads; however, the second-order hydrodynamic loads have an effect on a floating platform which is moored by a catenary mooring system. At the difference-frequencies of the incident wave components, the drift motion of a FOWT system is able to have large oscillation around its natural frequency. This paper presents the effects of second-order wave loads to the drift motion of a semi-submersible type. This work also aimed to validate the hydrodynamic model of Ulsan University (UOU) in-house codes through numerical simulations and model tests. The NREL FAST code was used for the fully coupled simulation, and in-house codes of UOU generates hydrodynamic coefficients as the input for the FAST code. The model test was performed in the water tank of UOU.

Dynamic Responses of a Spar Type Floating Offshore Wind Turbine With Failed Moorings

2020 ◽  
Author(s):  
Yajun Ren ◽  
Vengatesan Venugopal
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Mooring System ◽  
Floating Offshore Wind Turbine ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Platform Motions

Abstract The complex dynamic characteristics of Floating Offshore Wind Turbines (FOWTs) have raised wider consideration, as they are likely to experience harsher environments and higher instabilities than the bottom fixed offshore wind turbines. Safer design of a mooring system is critical for floating offshore wind turbine structures for station keeping. Failure of mooring lines may lead to further destruction, such as significant changes to the platform’s location and possible collisions with a neighbouring platform and eventually complete loss of the turbine structure may occur. The present study focuses on the dynamic responses of the National Renewable Energy Laboratory (NREL)’s OC3-Hywind spar type floating platform with a NREL offshore 5-MW baseline wind turbine under failed mooring conditions using the fully coupled numerical simulation tool FAST. The platform motions in surge, heave and pitch under multiple scenarios are calculated in time-domain. The results describing the FOWT motions in the form of response amplitude operators (RAOs) and spectral densities are presented and discussed in detail. The results indicate that the loss of the mooring system firstly leads to longdistance drift and changes in platform motions. The natural frequencies and the energy contents of the platform motion, the RAOs of the floating structures are affected by the mooring failure to different degrees.

Design Requirements for Floating Offshore Wind Turbines

2013 ◽  
Author(s):  
Xiaohong Chen ◽  
Qing Yu
Keyword(s):  
Wind Turbine ◽  
Case Studies ◽  
Wind Turbines ◽  
Offshore Wind ◽  
Design Parameters ◽  
Offshore Wind Turbine ◽  
Support Structure ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Design Requirements

This paper presents the research in support of the development of design requirements for floating offshore wind turbines (FOWTs). An overview of technical challenges in the design of FOWTs is discussed, followed by a summary of the case studies using representative FOWT concepts. Three design concepts, including a Spar-type, a TLP-type and a Semisubmersible-type floating support structure carrying a 5-MW offshore wind turbine, are selected for the case studies. Both operational and extreme storm conditions on the US Outer Continental Shelf (OCS) are considered. A state-of-the-art simulation technique is employed to perform fully coupled aero-hydro-servo-elastic analysis using the integrated FOWT model. This technique can take into account dynamic interactions among the turbine Rotor-Nacelle Assembly (RNA), turbine control system, floating support structure and stationkeeping system. The relative importance of various design parameters and their impact on the development of design criteria are evaluated through parametric analyses. The paper also introduces the design requirements put forward in the recently published ABS Guide for Building and Classing Floating Offshore Wind Turbine Installations (ABS, 2013).

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 Experimental Validation of Aero-Hydro-Servo-Elastic Models of a Scaled Floating Offshore Wind Turbine

2019 ◽  
Vol 9 (6) ◽  
pp. 1244 ◽  
Author(s):  
Kasper Jessen ◽  
Kasper Laugesen ◽  
Signe M. Mortensen ◽  
Jesper K. Jensen ◽  
Mohsen N. Soltani
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Experimental Validation ◽  
Numerical Models ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Scaled Model ◽  
Floating Offshore Wind Turbine ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

Floating offshore wind turbines are complex dynamical systems. The use of numerical models is an essential tool for the prediction of the fatigue life, ultimate loads and controller design. The simultaneous wind and wave loading on a non-stationary foundation with a flexible tower makes the development of numerical models difficult, the validation of these numerical models is a challenging task as the floating offshore wind turbine system is expensive and the testing of these may cause loss of the system. The validation of these numerical models is often made on scaled models of the floating offshore wind turbines, which are tested in scaled environmental conditions. In this study, an experimental validation of two numerical models for a floating offshore wind turbines will be conducted. The scaled model is a 1:35 Froude scaled 5 MW offshore wind turbine mounted on a tension-leg platform. The two numerical models are aero-hydro-servo-elastic models. The numerical models are a theoretical model developed in a MATLAB/Simulink environment by the authors, while the other model is developed in the turbine simulation tool FAST. A comparison between the numerical models and the experimental dynamics shows good agreement. Though some effects such as the periodic loading from rotor show a complexity, which is difficult to capture.

Validation of the Motion Analysis Method of Floating Offshore Wind Turbines Using Observation Data Acquired by Full Scale Demonstration Project

2019 ◽  
Author(s):  
Haruki Yoshimoto ◽  
Ken Kamizawa
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Demonstration Project ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Analysis Method ◽  
Floating Structure ◽  
Floating Offshore Wind Turbine ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

Abstract In recent years, the social demands for the introduction of renewable energy are increasing, demonstration projects of floating offshore wind turbine are being implemented and planned around the world. In Japan, a demonstration test named Fukushima FORWARD (Fukushima Floating Offshore Wind Farm Demonstration Project) has been conducted since 2011. Fukushima FORWARD is a project carried out by the Ministry of Economy, Trade and Industry, the world’s first floating offshore windfarm with a total capacity of 14 MW, including three floating offshore wind facilities and one floating offshore substation. In Fukushima FORWARD, Japan Marine United Corporation is in charge of floater part EPCI (Engineering, Procurement, Construction and Installation) of one floating offshore wind facility and one floating offshore substation. The floating offshore wind turbine (Ship Name: Fukushima Hamakaze) designed and built by Japan Marine United Corporation is equipped with a downwind 5 MW wind turbine. The floating structure adopts the advanced spar shape in order to reduce wave frequency motions and is moored by six spread catenary mooring lines. In the design of floating offshore wind turbines, it is important to estimate motions with high accuracy. Especially floating offshore wind turbine equipped with horizontal axis wind turbine requires heavy RNA (Rotor Nacelle Assembly) to be installed on the tower, and the floater motion greatly influences the design of the tower base. The tower base is required to have sufficient reliability because it directly leads to collapse of the wind turbine if it is damaged. On the other hand, the tower base is generally constructed with a cylinder made of extremely thick steel plate which is difficult to bend and weld, and if it has excessive safety factor the cost has increased greatly. Also, estimating the motion is the basis for estimating the load on the floating structure. In this paper, statistical analysis of long-term data measured by Fukushima FORWARD floating offshore wind turbine focusing on the motion and its features are introduced. In addition, we compare the motion obtained by potential theory and coupled analysis with actually measured motion using the measured wave and wind data and evaluate the validity of the analysis method.

Numerical Study on Aero-Hydrodynamics With Inter-Turbine Spacing Variation for Two Floating Offshore Wind Turbines

2019 ◽  
Author(s):  
Yang Huang ◽  
Decheng Wan
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Numerical Study ◽  
Offshore Wind ◽  
Hydrodynamic Characteristics ◽  
Offshore Wind Turbine ◽  
Analysis Tool ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Spacing Variation

Abstract To investigate the influence of the inter-turbine spacing on the performance of the floating offshore wind turbine (FOWT) in the floating wind farm, coupled aero-hydrodynamic simulations of two spar-type FOWT models with inter-turbine spacing variation under shear wind and regular wave conditions are performed in the present work. An unsteady actuator line model (UALM) is embedded into in-house code naoe-FOAM-SJTU to establish a fully coupled CFD analysis tool for numerical simulations of FOWTs. From the simulation results, the unsteady aerodynamic power and thrust are obtained, and the hydrodynamic responses including the six-degree-of-freedom motions and mooring tensions are available. Detailed flow visualizations of wake velocity profiles and vortex structures are also illustrated. The coupled performance of floating offshore wind turbines with inter-turbine spacing variation are analyzed, and the influences of inter-turbine spacing on aero-hydrodynamic characteristics of coupled wind-wave flow field are discussed. It is found that the power output of downstream wind turbine increases with inter-turbine spacing. Coupled aero-hydrodynamic characteristics of flow filed are significantly affected by inter-turbine spacing.

scholarly journals Improving the Strategy of Maintaining Offshore Wind Turbines through Petri Net Modelling

2021 ◽  
Vol 11 (2) ◽  
pp. 574
Author(s):  
Rundong Yan ◽  
Sarah Dunnett
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Petri Net ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Maintenance Costs ◽  
Offshore Wind Turbines ◽  
Major Repair ◽  
Wind Turbine System ◽  
Periodic Maintenance

In order to improve the operation and maintenance (O&M) of offshore wind turbines, a new Petri net (PN)-based offshore wind turbine maintenance model is developed in this paper to simulate the O&M activities in an offshore wind farm. With the aid of the PN model developed, three new potential wind turbine maintenance strategies are studied. They are (1) carrying out periodic maintenance of the wind turbine components at different frequencies according to their specific reliability features; (2) conducting a full inspection of the entire wind turbine system following a major repair; and (3) equipping the wind turbine with a condition monitoring system (CMS) that has powerful fault detection capability. From the research results, it is found that periodic maintenance is essential, but in order to ensure that the turbine is operated economically, this maintenance needs to be carried out at an optimal frequency. Conducting a full inspection of the entire wind turbine system following a major repair enables efficient utilisation of the maintenance resources. If periodic maintenance is performed infrequently, this measure leads to less unexpected shutdowns, lower downtime, and lower maintenance costs. It has been shown that to install the wind turbine with a CMS is helpful to relieve the burden of periodic maintenance. Moreover, the higher the quality of the CMS, the more the downtime and maintenance costs can be reduced. However, the cost of the CMS needs to be considered, as a high cost may make the operation of the offshore wind turbine uneconomical.

scholarly journals Physical Modelling of Offshore Wind Turbine Foundations for TRL (Technology Readiness Level) Studies

2021 ◽  
Vol 9 (6) ◽  
pp. 589
Author(s):  
Subhamoy Bhattacharya ◽  
Domenico Lombardi ◽  
Sadra Amani ◽  
Muhammad Aleem ◽  
Ganga Prakhya ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Prior Experience ◽  
Physical Modelling ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Foundation Design ◽  
Offshore Wind Turbines ◽  
Sea Bed ◽  
Geological Conditions

Offshore wind turbines are a complex, dynamically sensitive structure due to their irregular mass and stiffness distribution, and complexity of the loading conditions they need to withstand. There are other challenges in particular locations such as typhoons, hurricanes, earthquakes, sea-bed currents, and tsunami. Because offshore wind turbines have stringent Serviceability Limit State (SLS) requirements and need to be installed in variable and often complex ground conditions, their foundation design is challenging. Foundation design must be robust due to the enormous cost of retrofitting in a challenging environment should any problem occur during the design lifetime. Traditionally, engineers use conventional types of foundation systems, such as shallow gravity-based foundations (GBF), suction caissons, or slender piles or monopiles, based on prior experience with designing such foundations for the oil and gas industry. For offshore wind turbines, however, new types of foundations are being considered for which neither prior experience nor guidelines exist. One of the major challenges is to develop a method to de-risk the life cycle of offshore wind turbines in diverse metocean and geological conditions. The paper, therefore, has the following aims: (a) provide an overview of the complexities and the common SLS performance requirements for offshore wind turbine; (b) discuss the use of physical modelling for verification and validation of innovative design concepts, taking into account all possible angles to de-risk the project; and (c) provide examples of applications in scaled model tests.

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