Dynamic Response of a Multi-Megawatt Wind Turbine Drivetrain Under Voltage Dips Using a Coupled Flexible Multibody Approach

Author(s):  
Bart Blockmans ◽  
Jan Helsen ◽  
Frederik Vanhollebeke ◽  
Wim Desmet

High turbine reliability is of utmost importance to keep the cost of wind energy to a minimum. A considerable problem in this regard is that of premature drivetrain failures, which have plagued the wind turbine industry since its inception. Accurate prediction of the loads encountered by the drivetrain components during their lifetime is essential for reliable wind turbine design. Of particular interest are transient load events, which are expected to have a detrimental effect on the lifetime of drivetrain components, especially when they give rise to torque reversals. At the electrical side of the wind turbine, transient events worth investigating include grid faults, emergency stops and grid loss. Unlike previous research on the impact of these events, which typically uses simplified gearbox representations, this paper investigates the dynamic behavior of wind turbine drivetrains during grid faults using a coupled simulation of a flexible multibody model of a commercial multimegawatt wind turbine drivetrain and a Simulink model of a doubly fed induction generator (DFIG) and its controller. The mathematical modeling of the DFIG as well as the flexible multibody modeling of the drivetrain are described. Both gear and bearing forces on several components of the gearbox are examined during a symmetrical and asymmetrical voltage dip, and the influence of gearbox flexibility on these loads is assessed.

Author(s):  
Jan Helsen ◽  
Klaas Vanslambrouck ◽  
Frederik Vanhollebeke ◽  
Wim Desmet

The continuous demand for increase in power output for new wind parks under strict cost constraints, the greater wind resource at elevation and the desire for fewer machines per Mega-Watt to reduce operations resulted in a demand for bigger turbines. The drive train is an important component in realizing reliable and robust wind turbines. This paper investigates a geared wind turbine. In this type a gearbox is used to convert the low rotor speed to the required high generator speed. In the market several solutions are available to constrain the gearbox in the nacelle. The used configuration significantly determines the gearbox response to rotor loads and the transmission of gearbox vibrations to the turbine. This paper investigates the effectiveness of three configurations: the three point mounting, the double bearing configuration and the hydraulic damper system. The flexible multibody modeling technique can be used to accurately characterize gearbox dynamics. The goal of this work is to use an experimentally validated multibody model of a wind turbine drive train to characterize the ability of the three configurations to minimize the introduction of non-torque loads in the gearbox and the ability to isolate the gearbox vibrations from the rest of the turbine.


2021 ◽  
Author(s):  
◽  
Ramesh Kumar Behara

The growing needs for electric power around the world has resulted in fossil fuel reserves to be consumed at a much faster rate. The use of these fossil fuels such as coal, petroleum and natural gas have led to huge consequences on the environment, prompting the need for sustainable energy that meets the ever increasing demands for electrical power. To achieve this, there has been a huge attempt into the utilisation of renewable energy sources for power generation. In this context, wind energy has been identified as a promising, and environmentally friendly renewable energy option. Wind turbine technologies have undergone tremendous improvements in recent years for the generation of electrical power. Wind turbines based on doubly fed induction generators have attracted particular attention because of their advantages such as variable speed, constant frequency operation, reduced flicker, and independent control capabilities for maximum power point tracking, active and reactive powers. For modern power systems, wind farms are now preferably connected directly to the distribution systems because of cost benefits associated with installing wind power in the lower voltage networks. The integration of wind power into the distribution network creates potential technical challenges that need to be investigated and have mitigation measures outlined. Detailed in this study are both numerical and experimental models to investigate these potential challenges. The focus of this research is the analytical and experimental investigations in the integration of electrical power from wind energy into the distribution grid. Firstly, the study undertaken in this project was to carry out an analytical investigation into the integration of wind energy in the distribution network. Firstly, the numerical simulation was implemented in the MATLAB/Simulink software. Secondly, the experimental work, was conducted at the High Voltage Direct Centre at the University of KwaZulu-Natal. The goal of this project was to simulate and conduct experiments to evaluate the level of penetration of wind energy, predict the impact on the network, and propose how these impacts can be mitigated. From the models analysis, the effects of these challenges intensify with the increased integration of wind energy into the distribution network. The control strategies concept of the doubly fed induction generator connected wind turbine was addressed to ascertain the required control over the level of wind power penetration in the distribution network. Based on the investigation outcomes we establish that the impact on the voltage and power from the wind power integration in the power distribution system has a goal to maintain quality and balance between supply and demand.


Author(s):  
Curran A. Crawford

This paper provides a brief overview of functional design theory, which is then used to examine choices in wind turbine design. Definition of function is used to examine fundamental design choices in engineering a machine to capture energy from the wind. Specifically, rationalization is presented for a coning rotor wind turbine concept, potentially able to greatly reduce the cost of wind energy. The work presented here has provided a theoretical basis in design theory to motivate the development of specialized analysis tools and more detailed analysis of the concept.


Author(s):  
Jitendra P. Khatait ◽  
Dannis M. Brouwer ◽  
J. P. Meijaard ◽  
Ronald G. K. M. Aarts ◽  
Just L. Herder

The implementation of flexible instruments in surgery necessitates high motion and force fidelity and good controllability of the tip. However, the positional accuracy and the force transmission of these instruments are jeopardized by the friction, the clearance, and the inherent compliance of the instrument. The surgical instrument is modeled as a series of interconnected spatial beam elements. The endoscope is modeled as a rigid curved tube. The stiffness, damping, and friction are defined in order to calculate the interaction between the instrument and the tube. The effects of various parameters on the motion and force transmission behavior were studied for the axially-loaded and no-load cases. The simulation results showed a deviation of 1.8% in the estimation of input force compared with the analytical capstan equation. The experimental results showed a deviation on the order of 1.0%. The developed flexible multibody model is able to demonstrate the characteristic behavior of the flexible instrument for both the translational and rotational input motion for a given set of parameters. The developed model will help us to study the effects of various parameters on the motion and force transmission of the instrument.


Author(s):  
S. Schreck ◽  
M. Robinson

To further reduce the cost of wind energy, future turbine designs will continue to migrate toward lighter and more flexible structures. Thus, the accuracy and reliability of aerodynamic load prediction has become a primary consideration in turbine design codes. Dynamically stalled flows routinely generated during yawed operation are powerful and potentially destructive, as well as complex and difficult to model. As a prerequisite to aerodynamics model improvements, wind turbine dynamic stall must be characterized in detail and thoroughly understood. In the current study, turbine blade surface pressure data and local inflow data acquired by the NREL Unsteady Aerodynamics Experiment during the NASA Ames wind tunnel experiment were analyzed. The dynamically stalled, vortex dominated flow field responded in systematic fashion to variations in wind speed, turbine yaw angle, and radial location, forming the basis for more thorough comprehension of wind turbine dynamic stall and improved modeling.


2021 ◽  
Vol 9 ◽  
Author(s):  
Mingzhu Tang ◽  
Yutao Chen ◽  
Huawei Wu ◽  
Qi Zhao ◽  
Wen Long ◽  
...  

The number of normal samples of wind turbine generators is much larger than the number of fault samples. To solve the problem of imbalanced classification in wind turbine generator fault detection, a cost-sensitive extremely randomized trees (CS-ERT) algorithm is proposed in this paper, in which the cost-sensitive learning method is introduced into an extremely randomized trees (ERT) algorithm. Based on the classification misclassification cost and class distribution, the misclassification cost gain (MCG) is proposed as the score measure of the CS-ERT model growth process to improve the classification accuracy of minority classes. The Hilbert-Schmidt independence criterion lasso (HSICLasso) feature selection method is used to select strongly correlated non-redundant features of doubly-fed wind turbine generators. The effectiveness of the method was verified by experiments on four different failure datasets of wind turbine generators. The experiment results show that average missing detection rate, average misclassification cost and gMean of the improved algorithm better than those of the ERT algorithm. In addition, compared with the CSForest, AdaCost and MetaCost methods, the proposed method has better real-time fault detection performance.


2020 ◽  
Vol 49 (2) ◽  
pp. 203-236 ◽  
Author(s):  
Frank Lemmer ◽  
Wei Yu ◽  
Birger Luhmann ◽  
David Schlipf ◽  
Po Wen Cheng

Author(s):  
Bryan E. Kaiser ◽  
Svetlana V. Poroseva ◽  
Michael A. Snider ◽  
Rob O. Hovsapian ◽  
Erick Johnson

A relatively high free stream wind velocity is required for conventional horizontal axis wind turbines (HAWTs) to generate power. This requirement significantly limits the area of land for viable onshore wind farm locations. To expand a potential for wind power generation and an area suitable for onshore wind farms, new wind turbine designs capable of wind energy harvesting at low wind speeds are currently in development. The aerodynamic characteristics of such wind turbines are notably different from industrial standards. The optimal wind farm layout for such turbines is also unknown. Accurate and reliable simulations of a flow around and behind a new wind turbine design should be conducted prior constructing a wind farm to determine optimal spacing of turbines on the farm. However, computations are expensive even for a flow around a single turbine. The goal of the current study is to determine a set of simulation parameters that allows one to conduct accurate and reliable simulations at a reasonable cost of computations. For this purpose, a sensitivity study on how the parameters variation influences the results of simulations is conducted. Specifically, the impact of a grid refinement, grid stretching, grid cell shape, and a choice of a turbulent model on the results of simulation of a flow around a mid-sized Rim Driven Wind Turbine (U.S. Patent 7399162) and in its near wake is analyzed. This wind turbine design was developed by Keuka Energy LLC. Since industry relies on commercial software for conducting flow simulations, STAR-CCM+ software [1] was used in our study. A choice of a turbulence model was made based on the results from our previous sensitivity study of flow simulations over a rotating disk [2].


2022 ◽  
Vol 7 (1) ◽  
pp. 1-17
Author(s):  
Alessandro Croce ◽  
Stefano Cacciola ◽  
Luca Sartori

Abstract. Wind farm control is one of the solutions recently proposed to increase the overall energy production of a wind power plant. A generic wind farm control is typically synthesized so as to optimize the energy production of the entire wind farm by reducing the detrimental effects due to wake–turbine interactions. As a matter of fact, the performance of a farm control is typically measured by looking at the increase in the power production, properly weighted through the wind statistics. Sometimes, fatigue loads are also considered in the control optimization problem. However, an aspect which is rather overlooked in the literature on this subject is the evaluation of the impact that a farm control law has on the individual wind turbine in terms of maximum loads and dynamic response under extreme conditions. In this work, two promising wind farm controls, based on wake redirection (WR) and dynamic induction control (DIC) strategy, are evaluated at the level of a single front-row wind turbine. To do so, a two-pronged analysis is performed. Firstly, the control techniques are evaluated in terms of the related impact on some specific key performance indicators, with special emphasis on ultimate loads and maximum blade deflection. Secondarily, an optimal blade redesign process is performed with the goal of quantifying the modification in the structure of the blade entailed by a possible increase in ultimate values due to the presence of wind farm control. Such an analysis provides for an important piece of information for assessing the impact of the farm control on the cost-of-energy model.


2021 ◽  
Vol 6 (6) ◽  
pp. 1491-1500
Author(s):  
Liang Dong ◽  
Wai Hou Lio ◽  
Eric Simley

Abstract. To provide comprehensive information that will assist in making decisions regarding the adoption of lidar-assisted control (LAC) in wind turbine design, this paper investigates the impact of different turbulence models on the coherence between the rotor-effective wind speed and lidar measurement. First, the differences between the Kaimal and Mann models are discussed, including the power spectrum and spatial coherence. Next, two types of lidar systems are examined to analyze the lidar measurement coherence based on commercially available lidar scan patterns. Finally, numerical simulations have been performed to compare the lidar measurement coherence for different rotor sizes. This work confirms the association between the measurement coherence and the turbulence model. The results indicate that the lidar measurement coherence with the Mann turbulence model is lower than that with the Kaimal turbulence model. In other words, the potential value creation of LAC based on simulations during the wind turbine design phase, evaluated using the Kaimal turbulence model, will be diminished if the Mann turbulence model is used instead. In particular, the difference in coherence is more significant for larger rotors. As a result, this paper suggests that the impacts of different turbulence models should be considered uncertainties while evaluating the benefits of LAC.


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