Dynamic Modeling and Stability Analysis of a Dual-Rotor Wind Turbine

2018 ◽  
Author(s):  
Oliver T. Filsoof ◽  
Morten H. Hansen ◽  
Anders Yde ◽  
Xuping Zhang
Keyword(s):  
Wind Turbine ◽  
Dynamic Modeling ◽  
Wind Turbines ◽  
Floquet Theory ◽  
Equations Of Motion ◽  
Response Analysis ◽  
Modal Response ◽  
Asymmetric Rotor ◽  
Modal Property ◽  
Fidelity Model

Various modal analysis methods are available for single-rotor wind turbines, but there is no report and guidance on the modal property analysis of multi-rotor wind turbines. This paper presents a dynamic modeling method for the modal response analysis of a wind turbine with two three-bladed isotropic rotors. The equations of motion are derived using Lagrange’s equations and are further linearized at a steady-state equilibrium. To avoid using Floquet Theory to remove the periodic coefficients, multi-blade coordinates are utilized. Comparison between the numerical simulations and a high-fidelity model in HAWC2 shows agreements in terms of modal frequencies. The results shows that the whirling modes splits into symmetric and asymmetric rotor modes.

Dynamic Load Response Analysis on Yaw Bearing of Wind Turbine to Turbulent Wind

2019 ◽  
Author(s):  
Jianwen Xu
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Gumbel Distribution ◽  
Operating Conditions ◽  
Likelihood Method ◽  
Coupled Analysis ◽  
Response Analysis ◽  
Turbulent Wind ◽  
Load Response ◽  
Yaw Bearing

Abstract Wind turbines are subjected to dynamic loads during their service life. The yaw bearing is an important part which also bears these loads. In this study, a series of 5-megawatt (MW) wind turbines are analyzed for their dynamic response under normal operating conditions while exposed to turbulent wind. These models are Onshore, Monopile, ITI Barge, Spar, Tension-Leg Platform (TLP), Semi-Submerisible. TurbSim is used to prescribe turbulent-wind inflow and a time domain FAST code is applied in order to conduct the Aero-Hydro-Servo-Elastic coupled analysis on the yaw loads of the wind turbines. Three different average wind velocities are examined to compare the load response of the wind turbine to turbulent wind on the yaw bearing. A Gumbel distribution coupled maximum likelihood method is used to predict ultimate loads. And the rain flow counting algorithm, the linear cumulative damage law and S-N curve theory are used to predict the damage equivalent load. The results should aid the fatigue design of yaw bearing and the yaw control system according to different wind turbine design.

Flutter stability analysis of a perforated damping blade for large wind turbines

2017 ◽  
Vol 21 (3) ◽  
pp. 973-989
Author(s):  
Da-Gang Sun ◽  
Jin-Jun Guo ◽  
Yong Song ◽  
Bi-juan Yan ◽  
Zhan-Long Li ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Turbine Blades ◽  
Time Integration ◽  
Response Analysis ◽  
Damping Factor ◽  
Deformation Model ◽  
Structural Stiffness ◽  
Structural Damping ◽  
Comparison Results

The flutter stability of wind turbine blades is one of the important contents in the research of wind turbines. The bending stiffness of blades has decreased with the development of large-sized wind turbines. To achieve damping flutter-suppressing on the long spanwise blades, perforated damping blade was proposed under the consideration of the structural damping factor and the structural stiffness in this paper. Through the study of the unit cell, the deformation model was established and the structural loss factor of the perforated damping blade was derived. The undamped blade and the perforated damping blade, combined with the relevant parameters of a 1500 kW wind turbine blade, were established to simulate the flutter-suppressing abilities and the structural stability. The dynamic response analysis was accomplished with the large deformation theory, and the MPC algorithm was used to realize grid mobile and data delivery, according to the Newmark time integration method. The comparison results show that the perforated damping blade has both a higher structural damping factor and a better structural 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.

Response Analysis of a General Asymmetric Rotor-Bearing System

1980 ◽  
Vol 102 (1) ◽  
pp. 147-157 ◽  
Author(s):  
T. Inagaki ◽  
H. Kanki ◽  
K. Shiraki
Keyword(s):  
Dynamic Properties ◽  
Equations Of Motion ◽  
Harmonic Balance Method ◽  
Field Measurements ◽  
Transverse Mass ◽  
Response Analysis ◽  
Mass Moment ◽  
Rotor Bearing ◽  
Asymmetric Rotor ◽  
Bearing System

This paper presents an analytical method for the evaluation of the synchronous response of a general asymmetric rotor-bearing system. In the analysis, slightly asymmetric shaft stiffness in bending and shearing, which distribute along the rotor, and asymmetric transverse mass moment of inertia are considered. The dynamic properties of bearings and pedestals are assumed to be anisotropic and coupled in each direction. The equations of motion with periodic time dependent coefficients are solved by the Harmonic Balance Method and formulated to the transfer matrix. These solutions include the “Modified Holzer-Myklestad-Prohl Method by Lund & Orcutt” as a special case. The results of the analysis are confirmed by a simple model test and field measurements of large turbosets.

scholarly journals Low-Height Lifting System for Offshore Wind Turbine Installation: Modelling and Hydrodynamic Response Analysis Using the Commercial Simulation Tool SIMA

2020 ◽  
Author(s):  
David Vågnes ◽  
Thiago Gabriel Monteiro ◽  
Karl Henning Halse ◽  
Hans Petter Hildre
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Renewable Energy Sources ◽  
Weather Conditions ◽  
Economic Feasibility ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Response Analysis ◽  
Offshore Wind Turbines ◽  
Lifting System

Abstract With the increasing demand for renewable energy sources in the past years, the interest in expanding the use of wind energy has grown. The next frontier in this expansion process is the use of floating wind turbines offshore. One of the main factors dictating the economic feasibility of such wind turbines is the complexity of their installation process. The dimensions of modern offshore wind turbines, the distance from the installation sites to the coast and demanding environmental factors all contribute to the difficult of developing an efficient installation concept for this kind of structures. In this work, we present a new concept for a catamaran vessel capable of handling the deployment of offshore wind turbines on floating spar platforms using a low-height lifting system that connects to the lower end of the wind turbine. The low-height lifting system is controlled by an active heave compensation system and constant tension tugger wires attached to the turbine mid-section are used to ensure the balance of the tower during the installation process. We conducted a series of hydrodynamic analysis using the software suit SIMA to study the dynamic response of the proposed system under different weather conditions and different operational layouts. This preliminary concept was proven feasible from a hydrodynamic point of view and can now be pushed forward for further studies regarding other aspects of the operation, such as impact and structural loads and mechanical design of components.

scholarly journals Recent Advances in Integrated Response Analysis of Floating Wind Turbines in a Reliability Perspective

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Torgeir Moan ◽  
Zhen Gao ◽  
Erin E. Bachynski ◽  
Amir R. Nejad
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Early Stage ◽  
Response Assessment ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Response Analysis ◽  
Stage Of Development ◽  
System Integrity ◽  
Integrated Response

Abstract Offshore wind provides an important source of renewable energy. While wind turbines fixed to the seabed in shallow water have already been industrialized, floating wind turbines are still at an early stage of development. The cost of wind power is decreasing fast. Yet, the main challenges, especially for novel floating wind turbine concepts, are to increase reliability and reduce costs. The reliability perspective here refers to the lifecycle integrity management of the system to ensure reliability by actions during design, fabrication, installation, operation, and decommissioning. The assessment should be based on response analysis that properly accounts for the effect of different sub-systems (rotor, drivetrain, tower, support structure, and mooring) on the system behavior. Moreover, the load effects should be determined so as to be proper input to the integrity check of these sub-systems. The response analysis should serve as the basis for design and managing inspections and monitoring, with due account of inherent uncertainties. In this paper, recent developments of methods for numerical and experimental response assessment of floating wind turbines are briefly described in view of their use to demonstrate system integrity in design as well as during operation to aid inspection and monitoring. Typical features of offshore wind turbine behavior are also illustrated through some numerical case studies.

Parametric Instability and Localization of Vibrations in Three-Blade Wind Turbines

2018 ◽  
Vol 13 (7) ◽  
Author(s):  
Takashi Ikeda ◽  
Yuji Harata ◽  
Yukio Ishida
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Parametric Instability ◽  
Vertical Wind Shear ◽  
Coupled System ◽  
Basins Of Attraction ◽  
Response Curves ◽  
Softening Behavior

Nonlinear vibration characteristics of three-blade wind turbines are theoretically investigated. The wind turbine is modeled as a coupled system, consisting of a flexible tower with two degrees-of-freedom (2DOF), and three blades, each with a single degree of freedom (SDOF). The blades are subjected to steady winds. The wind velocity increases proportionally with height due to vertical wind shear. The natural frequency diagram is calculated with respect to the rotational speed of the wind turbine. The corresponding linear system with parametric excitation terms is analyzed to determine the rotational speeds where unstable vibrations appear and to predict at what rotational speeds the blades may vibrate at high amplitudes in a real wind turbine. The frequency response curves are then obtained by applying the swept-sine test to the equations of motion for the nonlinear system. They exhibit softening behavior due to the nonlinear restoring moments acting on the blades. Stationary time histories and their fast Fourier transform (FFT) results are also calculated. In the numerical simulations, localization phenomena are observed, where the three blades vibrate at different amplitudes. Basins of attraction (BOAs) are also calculated to examine the influence of a disturbance on the appearance of localization phenomena.

EXPERIMENTAL AND ANALYTICAL STUDIES OF VERTICAL AXIS WIND TURBINES

2018 ◽  
pp. 51-58
Author(s):  
B. P. Khozyainov
Keyword(s):  
Wind Turbine ◽  
Flow Velocity ◽  
Wind Power ◽  
Wind Turbines ◽  
Power Efficiency ◽  
Air Flow ◽  
Geometrical Parameters ◽  
Wind Speeds ◽  
Analytical Studies ◽  
Air Flow Velocity

The article carries out the experimental and analytical studies of three-blade wind power installation and gives the technique for measurements of angular rate of wind turbine rotation depending on the wind speeds, the rotating moment and its power. We have made the comparison of the calculation results according to the formulas offered with the indicators of the wind turbine tests executed in natural conditions. The tests were carried out at wind speeds from 0.709 m/s to 6.427 m/s. The wind power efficiency (WPE) for ideal traditional installation is known to be 0.45. According to the analytical calculations, wind power efficiency of the wind turbine with 3-bladed and 6 wind guide screens at wind speedsfrom 0.709 to 6.427 is equal to 0.317, and in the range of speed from 0.709 to 4.5 m/s – 0.351, but the experimental coefficient is much higher. The analysis of WPE variations shows that the work with the wind guide screens at insignificant average air flow velocity during the set period of time appears to be more effective, than the work without them. If the air flow velocity increases, the wind power efficiency gradually decreases. Such a good fit between experimental data and analytical calculations is confirmed by comparison of F-test design criterion with its tabular values. In the design of wind turbines, it allows determining the wind turbine power, setting the geometrical parameters and mass of all details for their efficient performance.

SHAPING OF AN AUTONOMOUS POWER SYSTEM FOR GUARANTEED POWER SUPPLY WITH THE PREDOMINANCE WIND ENERGY

2018 ◽  
pp. 28-50
Author(s):  
S. G. Ignatiev ◽  
S. V. Kiseleva
Keyword(s):  
Energy Storage ◽  
Wind Speed ◽  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Energy Demand ◽  
Diesel Generator ◽  
Average Wind Speed ◽  
Wind Speeds ◽  
Average Wind

Optimization of the autonomous wind-diesel plants composition and of their power for guaranteed energy supply, despite the long history of research, the diversity of approaches and methods, is an urgent problem. In this paper, a detailed analysis of the wind energy characteristics is proposed to shape an autonomous power system for a guaranteed power supply with predominance wind energy. The analysis was carried out on the basis of wind speed measurements in the south of the European part of Russia during 8 months at different heights with a discreteness of 10 minutes. As a result, we have obtained a sequence of average daily wind speeds and the sequences constructed by arbitrary variations in the distribution of average daily wind speeds in this interval. These sequences have been used to calculate energy balances in systems (wind turbines + diesel generator + consumer with constant and limited daily energy demand) and (wind turbines + diesel generator + consumer with constant and limited daily energy demand + energy storage). In order to maximize the use of wind energy, the wind turbine integrally for the period in question is assumed to produce the required amount of energy. For the generality of consideration, we have introduced the relative values of the required energy, relative energy produced by the wind turbine and the diesel generator and relative storage capacity by normalizing them to the swept area of the wind wheel. The paper shows the effect of the average wind speed over the period on the energy characteristics of the system (wind turbine + diesel generator + consumer). It was found that the wind turbine energy produced, wind turbine energy used by the consumer, fuel consumption, and fuel economy depend (close to cubic dependence) upon the specified average wind speed. It was found that, for the same system with a limited amount of required energy and high average wind speed over the period, the wind turbines with lower generator power and smaller wind wheel radius use wind energy more efficiently than the wind turbines with higher generator power and larger wind wheel radius at less average wind speed. For the system (wind turbine + diesel generator + energy storage + consumer) with increasing average speed for a given amount of energy required, which in general is covered by the energy production of wind turbines for the period, the maximum size capacity of the storage device decreases. With decreasing the energy storage capacity, the influence of the random nature of the change in wind speed decreases, and at some values of the relative capacity, it can be neglected.

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