Dynamic Responses of Spar Type Floating Offshore Wind Turbine Under Mooring Failure Conditions

2021 ◽  
Author(s):  
YAJUN REN ◽  
Vengatesan Venugopal
Keyword(s):  
Wind Turbine ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Offshore Wind Turbine ◽  
Failure Conditions

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.

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.

Effects of Fish Nets on the Nonlinear Dynamic Performance of a Floating Offshore Wind Turbine Integrated with a Steel Fish Farming Cage

2020 ◽  
Vol 20 (03) ◽  
pp. 2050042 ◽  
Author(s):  
Y. Lei ◽  
S. X. Zhao ◽  
X. Y. Zheng ◽  
W. Li
Keyword(s):  
Wind Turbine ◽  
Nonlinear Dynamic ◽  
Dynamic Performance ◽  
Fish Farming ◽  
Ocean Waves ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Offshore Wind Turbine ◽  
Wind Sea

This paper aims to study the effects of fish nets on the nonlinear dynamic performance of a floating offshore wind turbine integrated with a steel fish farming cage (FOWT-SFFC). Fully coupled aero-hydro-servo-elastic numerical models of FOWT-SFFC, with and without nets, are constructed to probe the nonlinear time-domain stochastic response. The first-order potential flow model with quadratic drag forces is employed to calculate the hydrodynamic loading on the foundation. The effects of nets on the damping ratios of 6 degree-of-freedom motions and on their displacement response amplitude operators (RAOs) are respectively investigated in numerical decay tests and monochromatic regular waves. The results show that the nets help to increase the damping level for the whole system and reduce motion RAOs when wave periods are around the natural periods of motions, while nets play insignificant role in motions when wave periods are far away from motion natural periods. The dynamic performances of FOWT-SFFC with and without nets under random ocean waves, the combined random wind and random waves as well as current are comprehensively compared and discussed. The simulation results indicate that in wind-sea dominated conditions, the nets tend to slightly increase the dynamic responses of FOWT-SFFC, especially the components corresponding to natural periods. Nonetheless, under sea states that comprise both wind-sea waves and swell, nets help to reduce the dynamic responses of FOWT-SFFC by introducing additional damping.

scholarly journals Dynamic Response for a Submerged Floating Offshore Wind Turbine with Different Mooring Configurations

2019 ◽  
Vol 7 (4) ◽  
pp. 115 ◽  
Author(s):  
Yane Li ◽  
Conghuan Le ◽  
Hongyan Ding ◽  
Puyang Zhang ◽  
Jian Zhang
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Mooring Line ◽  
Offshore Wind Turbine ◽  
Intermediate Water ◽  
Mooring System ◽  
Mooring Lines ◽  
Floating Offshore Wind Turbine

The paper discusses the effects of mooring configurations on the dynamic response of a submerged floating offshore wind turbine (SFOWT) for intermediate water depths. A coupled dynamic model of a wind turbine-tower-floating platform-mooring system is established, and the dynamic response of the platform, tensions in mooring lines, and bending moment at the tower base and blade root under four different mooring configurations are checked. A well-stabilized configuration (i.e., four vertical lines and 12 diagonal lines with an inclination angle of 30°) is selected to study the coupled dynamic responses of SFOWT with broken mooring lines, and in order to keep the safety of SFOWT under extreme sea-states, the pretension of the vertical mooring line has to increase from 1800–2780 kN. Results show that the optimized mooring system can provide larger restoring force, and the SFOWT has a smaller movement response under extreme sea-states; when the mooring lines in the upwind wave direction are broken, an increased motion response of the platform will be caused. However, there is no slack in the remaining mooring lines, and the SFOWT still has enough stability.

Transient response of a TLP-type floating offshore wind turbine under tendon failure conditions

2021 ◽  
Vol 220 ◽  
pp. 108486
Author(s):  
Haoyu Wu ◽  
Yongsheng Zhao ◽  
Yanping He ◽  
Yanlin Shao ◽  
Wengang Mao ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Transient Response ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Offshore Wind Turbine ◽  
Failure Conditions

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 Effects of Second-Order Hydrodynamics on the Dynamic Responses and Fatigue Damage of a 15 MW Floating Offshore Wind Turbine

2021 ◽  
Vol 9 (11) ◽  
pp. 1232
Author(s):  
Xuan Mei ◽  
Min Xiong
Keyword(s):  
Wind Turbine ◽  
Fatigue Damage ◽  
Second Order ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Extreme Condition ◽  
Offshore Wind Turbine ◽  
Floating Platform ◽  
Floating Offshore Wind Turbine ◽  
The Cost

In order to investigate the effects of second-order hydrodynamic loads on a 15 MW floating offshore wind turbine (FOWT), this study employs a tool that integrates AQWA and OpenFAST to conduct fully coupled simulations of the FOWT subjected to wind and wave loadings. The load cases covering normal and extreme conditions are defined based on the met-ocean data observed at a specific site. The results indicate that the second-order wave excitations activate the surge mode of the platform. As a result, the surge motion is increased for each of the examined load case. In addition, the pitch, heave, and yaw motions are underestimated when neglecting the second-order hydrodynamics under the extreme condition. First-order wave excitation is the major contributor to the tower-base bending moments. The fatigue damage of the tower-base under the extreme condition is underestimated by 57.1% if the effect of second-order hydrodynamics is ignored. In addition, the accumulative fatigue damage over 25 years at the tower-base is overestimated by 16.92%. Therefore, it is suggested to consider the effects of second-order wave excitations of the floating platform for the design of the tower to reduce the cost of the FOWT.

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