scholarly journals Structural Modeling and Failure Assessment of Spar-Type Substructure for 5 MW Floating Offshore Wind Turbine under Extreme Conditions in the East Sea

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6571
Author(s):  
Kwangtae Ha ◽  
Jun-Bae Kim ◽  
Youngjae Yu ◽  
Hyoung-Seock Seo
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Three Dimensional ◽  
Offshore Wind ◽  
East Sea ◽  
Offshore Wind Turbine ◽  
Fe Model ◽  
Offshore Wind Energy ◽  
Floating Offshore Wind Turbine ◽  
Load Analysis

Not only the driving for offshore wind energy capacity of 12 GW by Korea’s Renewable Energy 2030 plan but also the need for the rejuvenation of existing world-class shipbuilders’ infrastructures is drawing much attention to offshore wind energy in Korea, especially to the diverse substructures. Considering the deep-sea environment in the East Sea, this paper presents detailed modeling and analysis of spar-type substructure for a 5 MW floating offshore wind turbine (FOWT). This process uses a fully coupled integrated load analysis, which was carried out using FAST, a widely used integrated load analysis software developed by NREL, coupled with an in-house hydrodynamic code (UOU code). The environmental design loads were calculated from data recorded over three years at the Ulsan Marine buoy point according to the ABS and DNVGL standards. The total 12 maximum cases from DLC 6.1 were selected to evaluate the structural integrity of the spar-type substructure under the three co-directional conditions (45°, 135°, and 315°) of wind and wave. A three-dimensional (3D) structural finite element (FE) model incorporating the wind turbine tower and floating structure bolted joint connection was constructed in FEGate (pre/post-structural analysis module based on MSC NASTRAN for ship and offshore structures). The FEM analysis applied the external loads such as the structural loads due to the inertial acceleration, buoyancy, and gravity, and the environmental loads due to the wind, wave, and current. The three-dimensional FE analysis results from the MSC Nastran software showed that the designed spar-type substructure had enough strength to endure the extreme limitation in the East Sea based on the von Mises criteria. The current process of this study would be applicable to the other substructures such as the submersible type.

Global Responses and Loads Analysis of a 750-kW Semi-Submersible Floating Offshore Wind Turbine Under Extreme Environmental Conditions

2019 ◽  
Author(s):  
Thanh Dam Pham ◽  
Junbae Kim ◽  
Byoungcheon Seo ◽  
Rupesh Kumar ◽  
Youngjae Yu ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Environmental Conditions ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
East Sea ◽  
Offshore Wind Turbine ◽  
Test Model ◽  
Scaled Model ◽  
Floating Offshore Wind Turbine ◽  
Extreme Loads

Abstract A pilot floating offshore wind turbine project of Korea was proposed for installing in the East Sea of Korea. The prototype is a semisubmersible platform supporting a 750-kW wind turbine. A scaled model was tested in the basin tank of the University of Ulsan at scale ratio 1:40. The 750-kW floating offshore wind turbine was modeled by using the NREL-FAST code. Numerical results were validated by comparing with those of the test model. This paper analyzes dynamic responses and loads of the wind turbine system under extreme environmental conditions. Extreme environmental conditions based on metocean data of East Sea Korea. Extreme responses and extreme loads are important data for designing the structure of the 750 kW semi-submersible floating offshore wind turbine.

Advanced Concept Offshore Wind Turbine Development

2014 ◽  
Vol 18 (5) ◽  
pp. 728-735 ◽  
Author(s):  
Abdollah A. Afjeh ◽  
◽  
Brett Andersen ◽  
Jin Woo Lee ◽  
Mahdi Norouzi ◽  
...  
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Cost Savings ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Offshore Wind Energy ◽  
Offshore Wind Turbines ◽  
Floating Foundation ◽  
The Cost

Development of novel offshore wind turbine designs and technologies are necessary to reduce the cost of offshore wind energy since offshore wind turbines need to withstand ice and waves in addition to wind, a markedly different environment from their onshore counterparts. This paper focuses on major design challenges of offshore wind turbines and offers an advanced concept wind turbine that can significantly reduce the cost of offshore wind energy as an alternative to the current popular designs. The design consists of a two-blade, downwind rotor configuration fitted to a fixed bottom or floating foundation. Preliminary results indicate that cost savings of nearly 25% are possible compared with the conventional upwind wind turbine designs.

Floating offshore wind turbine fault diagnosis using stacked denoising autoencoder with temporal information

2021 ◽  
pp. 014233122110579
Author(s):  
Xujie Zhang ◽  
Ping Wu ◽  
Jiajun He ◽  
Yichao Liu ◽  
Lin Wang ◽  
...  
Keyword(s):  
Fault Diagnosis ◽  
Wind Energy ◽  
Wind Turbine ◽  
Temporal Information ◽  
Offshore Wind ◽  
Superior Performance ◽  
Series Data ◽  
Offshore Wind Turbine ◽  
Denoising Autoencoder ◽  
Floating Offshore Wind Turbine

Currently, the offshore wind turbine has become a hot research area in the wind energy industry. Among different offshore wind turbines, floating offshore wind turbine (FOWT) can harvest abundant wind energy in deepwater areas. However, the harsh working environment will dramatically increase the maintenance cost and downtime of FOWTs. Wind turbine fault diagnosis is being regarded as an indispensable system for maintenance issues. Owing to the complexity of FOWT, it imposes an enormous challenge for effective fault diagnosis. This paper develops a novel FOWT fault diagnosis method based on a stacked denoising autoencoder (SDAE). First, a sliding window technique is adopted for time-series data to preserve temporal information. Then, SDAE is employed to extract the features from high-dimensional data. Based on the extracted features from SDAE, a classifier using multilayer perceptrons (MLP) is developed to determine the health status of the FOWT. To verify the performance of the proposed method, a FOWT simulation benchmark based on the National Renewable Energy Laboratory (NREL) FAST simulator is employed. Results show the superior performance of the proposed method by comparison with other relevant methods.

scholarly journals Dynamic Responses for WindFloat Floating Offshore Wind Turbine at Intermediate Water Depth Based on Local Conditions in China

2021 ◽  
Vol 9 (10) ◽  
pp. 1093
Author(s):  
Shan Gao ◽  
Lixian Zhang ◽  
Wei Shi ◽  
Bin Wang ◽  
Xin Li
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Water Depth ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Mooring Line ◽  
Offshore Wind Turbine ◽  
Floating Offshore Wind Turbine ◽  
Coupled Method ◽  
Simplified Method

Offshore wind energy, a clean energy resource, is considered to be a possible alternative to fossil energy. Floating offshore wind technology is considered to be a proper concept to develop abundant wind energy in deep water. Considering the reality of offshore wind energy development in China, the floating offshore wind turbine concept is expected to be developed at moderate water depths. In this paper, a mooring system of the WindFloat semisubmersible floating offshore wind turbine (SFOWT) at a water depth of 60 m is designed. The dynamic responses of the WindFloat SFOWT under different wind–wave combination conditions are investigated using the coupled method and the simplified method, which do not include the effect of the tower top motion in the aerodynamic calculation. The results show that the dynamic responses of the WindFloat SFOWT, including the platform motions, tower loads, and mooring line tensions, perform fairly well at a moderate water depth. A comparison between the coupled method and simplified method shows that the calculated results are slightly different between the different conditions for the time domain results, response spectra results, and fatigue results. In addition, mooring line 1 (ML 1) suffers higher fatigue damage than ML2, which should be paid more attention.

scholarly journals Experimental and Numerical Analysis of a 10 MW Floating Offshore Wind Turbine in Regular Waves

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2608
Author(s):  
Hyeonjeong Ahn ◽  
Hyunkyoung Shin
Keyword(s):  
Wind Turbine ◽  
Model Test ◽  
Model Tests ◽  
Offshore Wind ◽  
East Sea ◽  
Irregular Waves ◽  
Offshore Wind Turbine ◽  
Regular Waves ◽  
Floating Offshore Wind Turbine ◽  
Floating Offshore Wind Turbines

Floating offshore wind turbines (FOWTs) experience fluctuations in their platforms, owing to the various wave and wind conditions. These fluctuations not only decrease the output of the wind power generation system, but also increase the fatigue load of the structure and various equipment mounted on it. Therefore, when designing FOWTs, efficient performance with respect to waves and other external conditions must be ensured. In this study, a model test was performed with a 10 MW floating offshore wind turbine. The model test was performed by scaling down a 10 MW FOWT model that was designed with reference to a 5 MW wind turbine and a semisubmersible platform by the National Renewable Energy Laboratory and the DeepCwind project. A scale ratio of 1:90 was used for the model test. The depth of the East Sea was considered as 144 m and, to match the water depth with the geometric similarity of mooring lines, mooring tables were installed. The load cases used in the model test are combined environmental conditions, which are combined uniform wind, regular waves and uniform current. Especially, Model tests with regular waves are especially necessary, because irregular waves are superpositions of regular waves with various periods. Therefore, this study aimed to understand the characteristics of the FOWTs caused by regular waves of various periods. Furthermore, in this model test, the effect of current was investigated using the current data of the East Sea. The results obtained through the model tests were the response amplitude operator (RAO) and the effective RAO for a six degrees-of-freedom motion. The results obtained from the model tests were compared with those obtained using the numerical simulation. The purpose of this paper is to predict the response of the entire system observed in model tests through simulation.

Fully-Coupled Aero-Hydrodynamic Simulation of Floating Offshore Wind Turbines by Different Simulation Methods

2018 ◽  
Author(s):  
Ping Cheng ◽  
Decheng Wan
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Platform ◽  
Hydrodynamic Simulation ◽  
Floating Offshore Wind Turbine ◽  
Floating Offshore Wind Turbines ◽  
Fully Coupled

To accurately predict the critical loads due to wind and wave is one of the common challenges in designing a floating offshore wind turbine (FOWT). The fully-coupled aero-hydrodynamic simulation of a floating offshore wind turbine, the NREL-5MW baseline wind turbine mounted on a semi-submersible floating platform, is conducted with two methods. Firstly, the in-house code naoe-FOAM-os-SJTU, which is developed on the open source platform OpenFOAM and coupled with the overset grid technique, is employed for the directly CFD computations. And another in-house code FOWT-UALM-SJTU developed by coupling the unsteady actuator line model (UALM) with naoe-FOAM-SJTU is also utilized for coupling simulations. In both models, the three-dimensional Reynolds Averaged Navier-Stokes (RANS) equations are solved with the turbulence model k-ω SST, and the Pressure-Implicit with Splitting of Operations (PISO) algorithm is applied to solve the pressure-velocity coupling equations. Both two solvers provide reasonable results of main aerodynamic loads as well as the main hydrodynamic forces. The FOWT-UALM-SJTU solver achieves better computational efficiency by simplifying the blade structure as actuator line models, while the naoe-FOAM-os-SJTU solver provides more accurate detailed flow information near the turbine blades.

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