scholarly journals Study of Dynamic Response Characteristics of the Wind Turbine Based on Measured Power Spectrum in the Eyewall Region of Typhoons

2019 ◽  
Vol 9 (12) ◽  
pp. 2392
Author(s):  
Ran Han ◽  
Long Wang ◽  
Tongguang Wang ◽  
Zhiteng Gao ◽  
Jianghai Wu
Keyword(s):  
Power Spectrum ◽  
Dynamic Response ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Beam Theory ◽  
Dynamic Responses ◽  
Limit Values ◽  
Actual Measurement ◽  
Fluctuating Wind ◽  
Measured Power

The present research envisages a method for calculating the dynamic responses of the wind turbines under typhoon. The measured power spectrum and inverse Fourier transform are used to generate the fluctuating wind field in the eyewall of the typhoon. Based on the beam theory, the unsteady aerodynamic model and the wind turbine dynamic model are coupled to calculate the dynamic response. Furthermore, using this method, the aeroelastic responses of a 6 MW wind turbine at different yaw angles are studied, and a 2 MW wind turbine are also calculated to verify the applicability of the results for different sizes of wind turbines. The results show that the turbulence characteristics of the fluctuating wind simulated by the proposed method is in good agreement with the actual measurement. Compared with the results simulated by the recommended power spectrum like the Kaimal spectrum, the energy distribution and variation characteristics simulated by the proposed method represent the real typhoon in a superior manner. It is found that the blade vibrates most violently at the inflow yaw angle of 30 degrees under the coupled effect of the aerodynamic, inertial and structural loads. In addition, the load on the tower exceeds the design limit values at the yaw angles of both 30 degrees and 120 degrees.

scholarly journals Dynamic Response of Articulated Offshore Wind Turbines under Different Water Depths

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2784
Author(s):  
Pei Zhang ◽  
Shugeng Yang ◽  
Yan Li ◽  
Jiayang Gu ◽  
Zhiqiang Hu ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Dynamic Responses ◽  
Wind Pressure ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Offshore Area ◽  
Offshore Wind Turbines ◽  
Water Depths

Focusing on the transitional depth offshore area from 50 m to 75 m, types of articulated foundations are proposed for supporting the NREL 5 MW offshore wind turbine. To investigate the dynamic behaviors under various water depths, three articulated foundations were adopted and numerical simulations were conducted in the time domain. An in-house code was chosen to simulate the dynamic response of the articulated offshore wind turbine. The aerodynamic load on rotating blades and the wind pressure load on tower are calculated based on the blade element momentum theory and the empirical formula, respectively. The hydrodynamic load is simulated by 3D potential flow theory. The motions of foundation, the aerodynamic performance of the wind turbine, and the loads on the articulated joint are documented and compared in different cases. According to the simulation, all three articulated offshore wind turbines show great dynamic performance and totally meet the requirement of power generation under the rated operational condition. Moreover, the comparison is based on time histories and spectra among these responses. The result shows that dynamic responses of the shallower one oscillate more severely compared to the other designs.

Evaluation of the Dynamic-Response-Based Intact Stability Criterion for Floating Wind Turbines

2015 ◽  
Author(s):  
Marco Masciola ◽  
Xiaohong Chen ◽  
Qing Yu
Keyword(s):  
Wind Speed ◽  
Dynamic Response ◽  
Wind Turbines ◽  
Stability Criterion ◽  
Area Ratio ◽  
Operating Conditions ◽  
Dynamic Responses ◽  
Stability Criteria ◽  
Intact Stability ◽  
Overturning Moment

As an alternative to the conventional intact stability criterion for floating offshore structures, known as the area-ratio-based criterion, the dynamic-response-based intact stability criteria was initially developed in the 1980s for column-stabilized drilling units and later extended to the design of floating production installations (FPIs). Both the area-ratio-based and dynamic-response-based intact stability criteria have recently been adopted for floating offshore wind turbines (FOWTs). In the traditional area-ratio-based criterion, the stability calculation is quasi-static in nature, with the contribution from external forces other than steady wind loads and FOWT dynamic responses captured through a safety factor. Furthermore, the peak wind overturning moment of FOWTs may not coincide with the extreme storm wind speed normally prescribed in the area-ratio-based criterion, but rather at the much smaller rated wind speed in the power production mode. With these two factors considered, the dynamic-response-based intact stability criterion is desirable for FOWTs to account for their unique dynamic responses and the impact of various operating conditions. This paper demonstrates the implementation of a FOWT intact stability assessment using the dynamic-response-based criterion. Performance-based criteria require observed behavior or quantifiable metrics as input for the method to be applied. This is demonstrated by defining the governing load cases for two conceptual FOWT semisubmersible designs at two sites. This work introduces benchmarks comparing the area-ratio-based and dynamic-response-based criteria, gaps with current methodologies, and frontier areas related to the wind overturning moment definition.

scholarly journals A Surface Ice Module for Wind Turbine Dynamic Response Simulation Using FAST

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Bingbin Yu ◽  
Dale G. Karr ◽  
Huimin Song ◽  
Senu Sirnivas
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Structural Response ◽  
Simulation Software ◽  
Offshore Wind ◽  
Foundation Soil ◽  
Offshore Wind Turbines ◽  
Ice Failure ◽  
Lock In

Developing offshore wind energy has become more and more serious worldwide in recent years. Many of the promising offshore wind farm locations are in cold regions that may have ice cover during wintertime. The challenge of possible ice loads on offshore wind turbines raises the demand of modeling capacity of dynamic wind turbine response under the joint action of ice, wind, wave, and current. The simulation software FAST is an open source computer-aided engineering (CAE) package maintained by the National Renewable Energy Laboratory. In this paper, a new module of FAST for assessing the dynamic response of offshore wind turbines subjected to ice forcing is presented. In the ice module, several models are presented which involve both prescribed forcing and coupled response. For conditions in which the ice forcing is essentially decoupled from the structural response, ice forces are established from existing models for brittle and ductile ice failure. For conditions in which the ice failure and the structural response are coupled, such as lock-in conditions, a rate-dependent ice model is described, which is developed in conjunction with a new modularization framework for FAST. In this paper, analytical ice mechanics models are presented that incorporate ice floe forcing, deformation, and failure. For lower speeds, forces slowly build until the ice strength is reached and ice fails resulting in a quasi-static condition. For intermediate speeds, the ice failure can be coupled with the structural response and resulting in coinciding periods of the ice failure and the structural response. A third regime occurs at high speeds of encounter in which brittle fracturing of the ice feature occurs in a random pattern, which results in a random vibration excitation of the structure. An example wind turbine response is simulated under ice loading of each of the presented models. This module adds to FAST the capabilities for analyzing the response of wind turbines subjected to forces resulting from ice impact on the turbine support structure. The conditions considered in this module are specifically addressed in the International Organization for Standardization (ISO) standard 19906:2010 for arctic offshore structures design consideration. Special consideration of lock-in vibrations is required due to the detrimental effects of such response with regard to fatigue and foundation/soil response. The use of FAST for transient, time domain simulation with the new ice module is well suited for such analyses.

Experimental Investigation on the Dynamic Response of a Three Legged Articulated Type Offshore Wind Tower

2016 ◽  
Author(s):  
Chinsu Mereena Joy ◽  
Anitha Joseph ◽  
Lalu Mangal
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Renewable Energy Sources ◽  
Offshore Structures ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Experimental Investigations ◽  
Offshore Wind Turbine ◽  
Ocean Engineering ◽  
Study Results

Demand for renewable energy sources is rapidly increasing since they are able to replace depleting fossil fuels and their capacity to act as a carbon neutral energy source. A substantial amount of such clean, renewable and reliable energy potential exists in offshore winds. The major engineering challenge in establishing an offshore wind energy facility is the design of a reliable and financially viable offshore support for the wind turbine tower. An economically feasible support for an offshore wind turbine is a compliant platform since it moves with wave forces and offer less resistance to them. Amongst the several compliant type offshore structures, articulated type is an innovative one. It is flexibly linked to the seafloor and can move along with the waves and restoring is achieved by large buoyancy force. This study focuses on the experimental investigations on the dynamic response of a three-legged articulated structure supporting a 5MW wind turbine. The experimental investigations are done on a 1: 60 scaled model in a 4m wide wave flume at the Department of Ocean Engineering, Indian Institute of Technology, Madras. The tests were conducted for regular waves of various wave periods and wave heights and for various orientations of the platform. The dynamic responses are presented in the form of Response Amplitude Operators (RAO). The study results revealed that the proposed articulated structure is technically feasible in supporting an offshore wind turbine because the natural frequencies are away from ocean wave frequencies and the RAOs obtained are relatively small.

scholarly journals Foundations, Design, and Dynamic Performance of Wind Turbines: Overview and Challenges in Sudan

2021 ◽  
Vol 9 (1) ◽  
pp. 96-103
Author(s):  
Ruba Asim Hamza ◽  
Amged Osman Abdelatif
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Structural Damage ◽  
Renewable Energy Sources ◽  
Dynamic Performance ◽  
Scaled Model ◽  
Static Loads ◽  
Design Loads ◽  
Foundation Type

Sudan is one of the developing countries that suffers from a lack of electricity, where the national electrification rate is estimated at 38.5%. In order to solve this problem, it is possible to use renewable energy sources such as wind energy. Beside many aspects to be considered at the design of wind turbine foundations, more attention should be given to the geotechnical part. There are many types of foundations for wind turbines. The foundation must satisfy two design criteria: 1) It should be safe against bearing failure in soils under design loads and settlements during the life of the structure must not cause structural damage; 2) In addition to static loads, wind turbine foundations loads are extremely eccentrically and the loading is usually highly dynamic. Therefore, the selection of foundation type should consider these two criteria taking into account the nature and magnitude of these loads. This paper presents a review of different types of wind turbine foundations of focusing on on-shore wind turbine foundation types and the dynamic response of wind turbine. The paper also demonstrate experimentally the dynamic response of the wind turbines using wind tunnel facility test on a scaled model.  

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.

Resonance Avoidance of Offshore Wind Turbines

2010 ◽  
Author(s):  
Martin L. Pollack ◽  
Brian J. Petersen ◽  
Benjamin S. H. Connell ◽  
David S. Greeley ◽  
Dwight E. Davis
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Structural Response ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Support Structure ◽  
Offshore Wind Turbines ◽  
Wind Turbine System ◽  
Dynamic Forces ◽  
Technical Basis

Coincidence of structural resonances with wind turbine dynamic forces can lead to large amplitude stresses and subsequent accelerated fatigue. For this reason, the wind turbine system is designed to avoid resonance coincidence. In particular, the current practice is to design the wind turbine support structure such that its fundamental resonance does not coincide with the fundamental rotational and blade passing frequencies of the rotor. For offshore wind turbines, resonance avoidance is achieved by ensuring that the support structure fundamental resonant frequency lies in the frequency band between the rotor and blade passing frequencies over the operating range of the turbine. This strategy is referred to as “soft-stiff” and has major implications for the structural design of the wind turbine. This paper details the technical basis for the “soft-stiff” resonance avoidance design methodology, investigates potential vulnerabilities in this approach, and explores the sensitivity of the wind turbine structural response to different aspects of the system’s design. The assessment addresses the wind turbine forcing functions, the coupled dynamic responses and resonance characteristics of the wind turbine’s structural components, and the system’s susceptibility to fatigue failure. It is demonstrated that the design practices for offshore wind turbines should reflect the importance of aerodynamic damping for the suppression of deleterious vibrations, consider the possibility of foundation degradation and its influence on the support structure’s fatigue life, and include proper treatment of important ambient sources such as wave and gust loading. These insights inform potential vibration mitigation and resonance avoidance strategies, which are briefly discussed.

scholarly journals A comparison between the dynamics of horizontal and vertical axis offshore floating wind turbines

2015 ◽  
Vol 373 (2035) ◽  
pp. 20140076 ◽  
Author(s):  
M. Borg ◽  
M. Collu
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Vertical Axis ◽  
Static Stability ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Frequency Range ◽  
Aerodynamic Forces ◽  
Horizontal Axis Wind Turbine ◽  
Support Structure

The need to further exploit offshore wind resources in deeper waters has led to a re-emerging interest in vertical axis wind turbines (VAWTs) for floating foundation applications. However, there has been little effort to systematically compare VAWTs to the more conventional horizontal axis wind turbine (HAWT). This article initiates this comparison based on prime principles, focusing on the turbine aerodynamic forces and their impact on the floating wind turbine static and dynamic responses. VAWTs generate substantially different aerodynamic forces on the support structure, in particular, a potentially lower inclining moment and a substantially higher torque than HAWTs. Considering the static stability requirements, the advantages of a lower inclining moment, a lower wind turbine mass and a lower centre of gravity are illustrated, all of which are exploitable to have a less costly support structure. Floating VAWTs experience increased motion in the frequency range surrounding the turbine [number of blades]×[rotational speed] frequency. For very large VAWTs with slower rotational speeds, this frequency range may significantly overlap with the range of wave excitation forces. Quantitative considerations are undertaken comparing the reference NREL 5 MW HAWT with the NOVA 5 MW VAWT.

Dynamic Response of an Elastic-Supported Bridge Beam Subjected to Velocity-Varied Moving Loads

2012 ◽  
Vol 594-597 ◽  
pp. 2802-2807
Author(s):  
Fu Liang Mei ◽  
Gui Ling Li
Keyword(s):  
Dynamic Response ◽  
Beam Theory ◽  
Dynamic Responses ◽  
Force Model ◽  
Superposition Method ◽  
Moving Loads ◽  
Coupled Vibration ◽  
Vehicle Model ◽  
Vibration Model ◽  
Mass Spring

Dynamic response of an elastic-supported bridge under speed-varied moving loads was investigated. A mathematical model of vehicle-bridge coupled oscillation for an elastic-supported bridge was built up by means of 1/4 vehicle model (Mass-Spring-Mass) and Euler-Bernoulli beam theory. And then dynamic equations of vehicle-bridge coupled oscillation in matrix form were established using two former orders general coordinates of an elastic-supported beam and model superposition method. The influences of vehicle-bridge coupled vibration model, elastic-supported stiffness, entrance speeds and acceleration /deceleration of moving loads on the dynamic responses of bridges were studied. Vehicle-bridge coupled vibration model based on 1/4 vehicle model can more accurately describe the dynamic characters of bridges than that based on constant moving force model. Elastic-supported stiffness only has an impact on the fluctuation amplitudes of dynamic responses. The vehicle-induced impact factor is dependent on the entrance speeds, acceleration/deceleration of moving loads and elastic-supported stiffness.

Influence of Wind Turbine Aero-Elastic Load on Dynamic Response of Floating Platform

2012 ◽  
Vol 608-609 ◽  
pp. 649-652
Author(s):  
Fa Suo Yan ◽  
Hong Wei Wang ◽  
Jun Zhang ◽  
Da Gang Zhang
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Numerical Code ◽  
Floating Body ◽  
Response Analysis ◽  
Floating Platform ◽  
Floating Base ◽  
Wind Turbine System ◽  
The Difference

A numerical code, known as COUPLE, which has been developed to perform hydrodynamic analysis of floating body with a mooring system, is extended to collaborate with FAST to evaluate the interactions between wind turbine and its floating base. FAST is developed by National Renewable Energy Lab (NREL) for aeroelastic simulation of wind turbines. A dynamic response analysis of a spar type floating wind turbine system is carried out by the method. Two types of simulation of wind load are used in the analysis. One type is a constant steady force and the other is a six-component dynamic load from a turbulent wind model. Numerical results of related platform motions under random sea conditions are presented in time and frequency domain. Comparison of results is performed to explain the difference of two analyses. The conclusions derived in this study may provide reference for the design of offshore floating wind turbines.

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