Size Of Wind Turbines Research Articles

Dynamic response simulation of an offshore wind turbine suspended by a floating crane

Recently, a number of wind turbines are being installed due to the increase of the interest in green energy. Such wind turbines are installed on land or offshore, and most of them are being installed on land because of easy installation. However, because it is possible to get better wind quality in offshore, the request for an offshore wind turbine is increasing and some heavy industries including shipyards are producing different sizes of offshore wind turbines. A floating crane is used for constructing the offshore wind turbine because its weight amounts to several hundred tons. Thus, it is very important to secure the safety during the construction. In this study, a dynamic response simulation of the offshore wind turbine suspended by the floating crane is performed. For this, we supposed that the motion of the floating crane and the wind turbine has 14 degrees of freedom, and there is the interaction by constraints among them. In addition, hydrostatic and hydrodynamic forces which are independent of each other are considered as external forces acting on the floating crane. The simulation result can be used for the verification of the safety of the construction method which the offshore wind turbine is constructed by the floating crane and the application guidance of this method.

Wind turbine rotor fragments: impact probability and setback evaluation

With increasing installation of wind turbines, the exposure to the hazard of impact from blade fragments increases. Local authorities use setbacks to reduce the risk by limiting the distance from wind turbines to adjacent property lines and dwellings. Unduly conservative setbacks are a deterrent to wind energy development. To determine appropriate setbacks, the authors developed a fragment trajectory model based on fragment rotation and aerodynamics. The model was used to simulate fragment trajectories at various rotor speeds, with randomly generated inputs for wind speed, wind direction, rotor azimuth, and rotor break position. Four sizes of wind turbines were studied, with rated power of 750 kW, 1.5, 3 and 5 MW. A sensitivity analysis showed that a fragment trajectory is highly dependent on the input parameters. However, for multiple trajectories from a given turbine and rotor speed, the sensitivity of the impact probability to most inputs was negligible. The results indicate that the range increased with turbine rating and rotor speed. When the range was normalized by overall turbine height, the probability of impact at a particular normalized range decreases with turbine rating. Planning agencies use the normalized range for setbacks, and the results indicate that using a common setback for all turbine sizes would be reasonable. Existing setback standards of 2–3 overall turbine heights offer better than 1 in 1,000,000 probability of impact per year; however, setbacks approaching 1 turbine height will have an order of magnitude higher probability of impact.

Technological Diversity and Economics: Coupling Effects on Hydrogen Production from Biomass

This review evaluates a diverse portfolio of technologies that produce hydrogen from renewable energy sources. A number of literature surveys and efficient hydrogen formation pathways are compared. The continuous improvement in hydrogen production pathways is of crucial importance in the making of hydrogen from sustainable energy sources. Evaluation of the economics in producing hydrogen from natural gas (NG), coal, biomass, atoms, sunlight and wind shows that the key to commercialization of hydrogen energy depends on feedstock cost, raw material availability, capital costs of equipment and how long the technology has been established. Estimates reveal that the hydrogen production cost (HPC) from coal is expected to be 0.36 to 1.83 US$/kg, whereas for NG it is 2.48 to 3.17 US$/kg. Depending on the type and cost of raw material employed, the HPC from biomass is expected to be in range of 1.44 to 2.83 US$/kg, while the HPC from wind is expected to be 5.50 US$/kg depending on the size of wind turbines and type of electrolyzers used. Compared to the HPC from coal and NG, the HPC from solar energy is much more higher (by more than 3 orders of magnitude). Considering the capital cost, energy consumption and operating costs, a HPC of 8 US$/kg would be expected for the electrolysis of water. Nevertheless, if the cost of electricity is low, then it would be possible to produce hydrogen from solar and water electrolysis at a cheaper rate. This result implies that hydrogen production from coal, biomass and NG resources will be great enough to meet hydrogen demands in the near future. Of all of the current technologies employed for the yield of hydrogen from fuels, steam methane reforming (SMR) seems to be the most practical and established technology. By the SMR pathway, HPC from NG is expected to be 3.50 US$/kg and 1.25 US$/kg for small and large plant sizes, respectively, while the HPC from NG is estimated to have a cost of 6 US$/GJ. However, production technologies including thermochemical pathways such as biomass gasification, pyrolysis, and supercritical water gasification (SCWG) and biological pathways such as photosynthesis, fermentation, and biological water gas shift reactions (BWGS) are also discussed.

Analysis and design of Coleman transform‐based individual pitch controllers for wind‐turbine load reduction

AbstractAs the size of wind turbines increases, the effects of dynamic loading on the turbine structures become increasingly significant. There is therefore a growing demand for turbine control systems to alleviate these unsteady structural loads in addition to maintaining basic requirements such as power and speed regulation. This has motivated the development of blade individual pitch control (IPC) methodologies, many of which employ the Coleman transformation to simplify the controller design process. However, and as is shown in this paper, the Coleman transformation significantly alters the rotational system dynamics when these are referred to the non‐rotating frame of reference, introducing tilt–yaw coupling in the process. Unless this transformation is explicitly included in the model employed for IPC design, then the resulting controllers can yield poor performance. Therefore, in this paper, we show how to model the Coleman transformation in a form that is amenable to IPC analysis and synthesis. This enables us to explain why traditional design parameters of gain and phase margin are poor indicators of robust stability and hence motivate the need for a multivariable design approach. The robust multivariable IPC approach advocated in this paper is based upon loop shaping and has numerous desirable properties, including reliable stability margins, improved tilt–yaw decoupling and simultaneous rejection of disturbance loads over a range of frequencies. The design of a robust multivariable IPC is discussed, and simulation results are presented that demonstrate the efficacy of this controller, in terms of load reduction on both rotating and non‐rotating turbine parts. Copyright © 2014 John Wiley & Sons, Ltd.

Methods of modeling slope discontinuities in large size wind turbine blades using absolute nodal coordinate formulation

This paper describes and evaluates the use of the Absolute Nodal Coordinate Formulation (ANCF) in modeling large size wind turbine blades. Modern blade model can be divided into two regions classified by aerodynamic and structural function. The aerodynamic region, blade-span, is utilizing the thinnest possible airfoil section. On the other hand, the transition between the circular mount and the first airfoil profile is referred as blade-root region, which carries highest loads along the blade. In this investigation, an efficient procedure is developed for mapping NACA airfoil wind-turbine blades into ANCF thin plate models. The procedure concerns a complete wind turbine blade structure, blade-root as well as the blade-span regions with non-uniform and twisted nature. As a result, the slope discontinuity problem arises in both chord-wise and span-wise directions, and consequently presents numerical errors in dynamic simulation. The paper investigates the methods of modeling slope discontinuity resulting from the variations of the cross-sectional layouts across the blade. The developed method is applied for the gradient-deficient thin plate element in order to account for structural discontinuity. In addition, the aerodynamic loads are precisely expressed and the aerodynamic characteristics of such blades are examined with the ANCF and with the classical finite element method. The static and dynamic solutions of different operating conditions are obtained and results are compared with those obtained using ANSYS code. Both the limitations and advantages of using the ANCF in modeling large size wind turbine blades are concluded and discussed. A Dynamics for Design (DFD) procedure is presented with numerical example concerning large-rotation, large deformation wind turbine blades.

Analysis of load reduction possibilities using a hydraulic soft yaw system for a 5-MW turbine and its sensitivity to yaw-bearing friction

With the increasing size of wind turbines and with increasing lifetime demands, new methods for load reduction in the turbines need to be examined. One method is to make the yaw system of the turbine flexible, thereby dampening the loads to the system. This paper presents a hydraulic soft yaw concept and investigates the effect this has on critical loads in the turbine. To analyze the system, a novel friction model is developed and implemented for the yaw system using the NREL 5-MW turbine in the aerodynamic code FAST. Based on this model, the influence of friction is investigated and the results on load reduction for three different design load cases are presented and discussed. From the investigation, it is found that load reductions of up to 40% on fatigue loads and 37% on ultimate loads are possible when considering the yaw system.

Damage detection method for wind turbine blades based on dynamics analysis and mode shape difference curvature information

Blades are among the key components of wind turbines. Blade damage is one of the most common types of structural defects and can cause catastrophic structural failure. Therefore, it is highly desirable to detect and diagnose blade damage as early as possible. In this paper, we propose a method for blade damage detection and diagnosis. This method incorporates finite element method (FEM) for dynamics analysis (modal analysis and response analysis) and the mode shape difference curvature (MSDC) information for damage detection/diagnosis. Finite element models of wind turbine blades have been built and modified via frequency comparison with experimental data and the formula for the model updating technique. Our numerical simulation results have demonstrated that the proposed technique can detect the spatial locations of damages for wind turbine blades. Changes in natural frequencies and modes for smaller size blades with damage are found to occur at lower frequencies and lower modes than in the larger sized blade case. The relationship between modal parameters and damage information (location, size) is very complicated especially for larger size blades. Moreover, structure and dynamic characters for larger size blades are different from those for smaller sized blades. Therefore, dynamic response analysis for a larger sized wind turbine blade with a multi-layer composite material based on aerodynamic loads’ (including lift forces and drag forces) calculation has been carried out and improved the efficiency and precision to damage detection by combining (MSDC) information. This method provides a low cost and efficient non-destructive tool for wind turbine blade condition monitoring.

A feasibility study of a stand-alone hybrid solar–wind–battery system for a remote island

This paper presents a detailed feasibility study and techno-economic evaluation of a standalone hybrid solar–wind system with battery energy storage for a remote island. The solar radiation and wind data on this island in 2009 was recorded for this study. The HOMER software was employed to do the simulations and perform the techno-economic evaluation. Thousands of cases have been carried out to achieve an optimal autonomous system configuration, in terms of system net present cost (NPC) and cost of energy (COE). A detailed analysis, description and expected performance of the proposed system were presented. Moreover, the effects of the PV panel sizing, wind turbine sizing and battery bank capacity on the system’s reliability and economic performance were examined. Finally, a sensitivity analysis on its load consumption and renewable energy resource was performed to evaluate the robustness of economic analysis and identify which variable has the greatest impact on the results. The results demonstrate the techno-economic feasibility of implementing the solar–wind–battery system to supply power to this island.

Techno-economic analysis of wind turbine–PEM (polymer electrolyte membrane) fuel cell hybrid system in standalone area

Providing reliable, environmentally friendly, and affordable energy has been a goal for many countries throughout the world. Hydrogen is presented as new energy sources during the last years which can be utilized instead of fossil fuel. One of the most promising clean methods of obtaining hydrogen is using renewable sources like wind and solar energy via electrolysis. In present work, a techno-economic evaluation of wind-hydrogen hybrid system (wind turbine, electrolysis, and PEM (polymer electrolyte membrane) fuel cell) in household size will be considered. In order to save the extra energy of wind turbine, electrolysis is used to convert this energy into hydrogen chemical energy. Generated hydrogen is stored in hydrogen storage tank. PEM fuel cell is applied to convert chemical energy of hydrogen into electrical power with high efficiency when extra power is required. Results show that wind energy in Manjil and Binaloud (two cities which have wind power plant in Iran) has greater wind speed in comparison with other cities. Also result shows that in standalone application, the size of wind turbine is bigger than the on-grid one to supply the full load consumption and it makes the standalone application too expensive.

Low voltage ride-through of DFIG and brushless DFIG: Similarities and differences

The brushless doubly fed induction generator (BDFIG) has been proposed as a viable alternative in wind turbines to the commonly used doubly fed induction generator (DFIG). The BDFIG retains the benefits of the DFIG, i.e. variable speed operation with a partially rated converter, but without the use of brush gear and slip rings, thereby conferring enhanced reliability.As low voltage ride-through (LVRT) performance of the DFIG-based wind turbine is well understood, this paper aims to analyze LVRT behavior of the BDFIG-based wind turbine in a similar way. In order to achieve this goal, the equivalence between their two-axis model parameters is investigated. The variation of flux linkages, back-EMFs and currents of both types of generator are elaborated during three phase voltage dips. Moreover, the structural differences between the two generators, which lead to different equivalent parameters and hence different LVRT capabilities, are investigated.The analytical results are verified via time-domain simulations for medium size wind turbine generators as well as experimental results of a voltage dip on a prototype 250kVA BDFIG.

Evaluation of Wind Energy Generation and Site Pairing of Wind Turbines in Algeria

This paper addresses assessment of wind generation potentiality in Algeria and analyze of energy exchange between the wind and a Wind Energy Conversion System (WECS). Wind data gathered at 10 m high is based on the atlas of the wind of Algeria established by the National office of the Meteorology runs 37 stations of measures. The data is used for a feasibility analysis of optimum future utilization of Wind generator potentiality in 14 sites covering all landscape types and regions in Algeria. A mathematical formulation using a two-parameter Weibull wind speed distribution is further established to estimate the yearly mean wind speed and the yearly average available wind energy flux for each site. Detailed technical assessment for the ten most promising potential wind sites was made using the capacity factor and the site effectiveness approach. The investigation was performed assuming twelve models of small, medium and big size wind machines representing different ranges of characteristic speeds and rated power suitable for water pumping and electric supply. The results show that small wind turbines could be installed in some coast region and medium wind turbines could be installed in the high plateau and some desert regions and utilized for water supply and electrical power generation, the sites having an important wind deposit, in high plateau we find Tiaret site's but in the Sahara there is some sites for example Adrar, Timimoun, In Amenas and In Salah, in these sites could be installed a medium or a big size wind turbines, provided the correct wind machine-site is selected.

Evaluation of community response to wind turbine-related noise in western New York state.

As the boundaries of harvesting wind energy expand to meet the ever-increasing societal energy demands, the number and size of wind turbines being constructed rises. As part of a larger project to monitor sound in an operating wind park in western New York State, a cross-sectional survey was conducted among individuals living in and around the wind park to characterize the perception, level of annoyance, and self-reported health effects of residents. We conducted the study in a 126 MW wind park consisting of 84 turbines spanning approximately 19 square miles of farmland. Short-term outdoor and indoor sound level measurements were also performed at each dwelling in which a questionnaire was administered. To our knowledge, this study is the first to collect sound measurements at individual residences. There was no apparent exposure-response relationship between an individual's level of annoyance and the short duration sound measurements collected at the time of the survey. There was a correlation between an individual's concern regarding health effects and the prevalence of sleep disturbance and stress among the study population. The siting process is unique to each community with varying degrees of success. Additional sound level measurements inside and outside homes in larger cohorts in concert with detailed questionnaires would be useful in verifying those exposure-response relationships found in studies using calculated sound level data. Additional research should include a detailed investigation of sleep patterns and possible disturbance in those living in and near operating wind turbine projects.

Modeling and Simulation of Grid Connected Wind Energy Conversion System Based on a Doubly Fed Induction Generator (DFIG)

This paper deals with the analysis, modeling, and control of a grid connected doubly-fed induction generator (DFIG) driven by the wind turbine. Recent advancements in size and technology of wind turbines require sophisticated control systems to effectively optimize energy conversion and enhance grid integration. This article investigates the power flow analysis of grid connected Wind Energy Conversion System (WECS) in a highly fluctuating wind environment. The WECS is equipped with a DFIG and a back-to-back converter in the rotor circuit. A control technique is presented for extracting the maximum power from the wind turbine. The grid side converter maintains the DC link voltage and the task of the rotor side converter is to track the maximum power point for the wind turbine. The description for the proposed system is presented with the detailed dynamic modeling equations. Simulation results for different operating conditions are presented. speed. Because the power converter only process the slip rotor power, which is typically 25% of the rated output power, the DFIG offers the advantages of speed control for a reduction in cost and power losses (2)-(3). This paper presents a DFIG wind turbine system that is modeled in Matlab/Simulink and PLECS. A full electrical model is implemented that includes the power converter for the rotor side and a dq model of the induction machine. The aerodynamics of the wind turbine and the mechanical dynamics of the induction machine are included to extend the use of the model for variable wind speed conditions. For longer simulations that include these slower mechanical and wind dynamics, an averaged PWM converter model is presented. The averaged electrical model offers improved simulation speed at the expense of neglecting converter switching detail. The main feature of the implemented model is the possibility to investigate topics related to the diagnosis and Low Voltage Ride Trough (LVRT) capability of WECS. Simulation results for different operating conditions are presented in this paper, whereas the LVRT characteristics will be analyzed in a next paper.

Bearing Resistance of Wind Turbine Generator System

The vertical axis wind turbine generator is mainly used for small size wind turbine applications, and is independent of wind direction. Its rotating part (shaft unit) should be rotated by an extremely small torque so as to increase the generation efficiency. However, commercially available bearings are not necessarily suitable for the shaft unit because their static and dynamic load ratings are frequently larger than those required for the vertical axis wind turbine. As a result, the frictional force and the rotating torque of commercially available bearings are too large for the shaft unit to rotate lightly. In this study, through an experiment with an actual vertical axis wind turbine, the bearings used for the shaft unit are reviewed in accordance with IEC61400-2. The design of the shaft unit with the bearings having the most suitable load rating and frictional force for the vertical axis wind turbine is attempted. The newly designed shaft unit will be applied to the vertical axis wind turbine and will be tested.

Assessment Parameters and Matching between the Sites and Wind Turbines

Abstract The objective of this paper is to introduce the assessment parameters of the wind energy production of sites and pairing between the sites and wind turbines. The exploration is made with the wind data gathered at 10 m high is based on the atlas of the wind of Algeria established by the National office of the Meteorology runs 37 stations of measures. The data is used for a feasibility analysis of optimum future utilization of Wind generator potentiality in five promising sites covering a part of landscape types and regions in Algeria. Detailed technical assessment for the ten most promising potential wind sites was made using the capacity factor and the site effectiveness approach. The investigation was performed assuming several models of small, medium and big size wind machines representing different ranges of characteristic speeds and rated power suitable for water pumping and electric supply. The results show that small wind turbines could be installed in some coast region and medium wind turbines could be installed in the high plateau and some desert regions and utilized for water supply and electrical power generation, the sites having an important wind deposit, in high plateau we find Tiaret site's but in the desert there is some sites for example Adrar, Timimoun and In Amenas, in these sites could be installed a medium and big size wind turbines.

Along-wind simplified analysis of wind turbines through a coupled blade-tower model

A model is proposed to analyse the along-wind dynamic response of upwind turbines with horizontal axis under service wind conditions. The model takes into account the dynamic coupling effect between rotor blades and supporting tower. The wind speed field is decomposed into a mean component, accounting for the well-known wind shear effect, and a fluctuating component, treated through a spectral approach. Accordingly, the so-called rotationally sampled spectra are introduced for the blades to account for the effect of their rotating motion. Wind forces acting on the rotor blades are calculated according to the blade element momentum model. The tower shadow effect is also included in the present model. Two examples of a large and medium size wind turbines are modelled, and their dynamic response is analysed and compared with the results of a conventional static analysis.

Micro Wind Turbines for Energy Gathering in Build Up Areas

In a city environment, wind direction is often not predictable and is easily re-directed in different ways by all kinds of obstacles. Consequently, large size wind turbines do not work effectively, not to mention the requirement for planning permission often needed for their installation. In an attempt to overcome these problems, this paper proposes the design of vertical-axis micro turbines with a maximum diameter of 30cm, which generate electric power for low voltage DC loads. The paper looks at the design, simulation and construction of a combination of Savonius-type, H-type and Darrieustype blade turbines. A variety of mechanical and electrical aspects of the turbine design are studied in detail to enhance the electrical output efficiency of the turbines. The results indicate that the most efficient turbine makes use of a combination of different blade designs, resulting in a power coefficient of 42% and an average total efficiency of about 32%. Additionally, the turbine has a high electric power output, a good self-starting characteristic, and low starting and cut-in wind speeds of 2.25m/s and 2.75m/s respectively. It also benefits from a simple mechanical structure and can therefore be produced cheaply.

Development of wireless laser blade deflection monitoring system for mobile wind turbine management host

This study proposes a wireless laser displacement sensor system for in situ deflection monitoring of wind turbine blades. This system consists of a tower-installed laser displacement sensor system composed of a laser displacement sensor head, controller, Zigbee transmitter, and analog-to-digital converter module, combined with a mobile host that includes a Zigbee receiver and a laptop. In contrast to the approach of blade sensor installation, the laser displacement sensor system is installed in the tower to enable noncontact blade displacement monitoring. The concepts of direct noncontact remote sensing and actuation from the tower and remote power delivery from the tower to blade-installed sensors and actuators will enable various approaches for wind turbine structural health monitoring. The proposed system can easily identify problems related to deflection. The size of wind blades increases with energy demands. Due to the large size of wind turbines, current wind turbines are installed very high above ground level. It is impractical to monitor the results from laser displacement sensor through wired connection in these cases. Hence, wired connections of laser displacement sensors to base monitoring stations must be replaced with a wireless solution. This wireless solution is achieved using Zigbee technology. The output from the laser displacement sensor is fed to a microcontroller, which acts as an analog-to-digital converter. The output from the microcontroller is connected to the Zigbee transceiver module, which transmits the data, and at the other end, the Zigbee reads the data and displays it on a PC, from which users can monitor the condition of the wind blades.

Wind Tower System With a Helical Wind Deflecting Structure, Computational Fluid Dynamics, and Experimental Studies

A wind tower system having a three dimensional heliacal wind deflecting structure is studies in this work. The purpose of the helical structure is to increase the natural wind speed and direct the follow of the wind toward two columns of horizontal-axis rooftop-size wind turbines that are installed in the grooves of the helical structure, diametrically opposed to each other. Computational fluid dynamics analyses were conducted to determine the influence of the helical structure on the wind speed reaching the turbines. A wind speed amplification coefficient was determined for a helical structure of 6.7 m outer diameter. The velocity profiles of the wind flow around the helical structure were determined under a postulated wind speed of 4.47 m/s. The flow was modeled as turbulent with a Reynolds Number of 2,052,167. Standard “k–ε” turbulent model with “near wall treatment” and “standard wall function” were adapted in all analysis. A “y+” value of 50 was held constant in all simulation. The grid-size effects on the accuracy of the results were examined. Convergence criterion was satisfied in each case. This study shows that the helical structure having an outer diameter of 6.7 m results in an average wind speed increase factor of 1.52. An experimental wind tower system was fabricated and installed at an elevation of 40 m above the ground. The wind tower system comprised of four identical rooftop size wind turbines, each having 1.6 KW name-plate-rating. A helical wind deflecting structure of 11 m tall, and 7 m in major diameter was used in fabrication of the tower. An active yaw-control mechanism was used to orient the tower into the prevailing wind. The experimental results show that as the result of the use of the wind deflecting structure, an average power amplification factor of 4.69 was obtained for the tower, in comparison with the standard standalone installation of the four wind turbines.

Empirical correlation between hub height and local wind shear exponent for different sizes of wind turbines

Abstract The increasing rate of adverse environmental events has made people from all walks of life more aware of the utilization of clean and renewable sources of energy. Technological advancement and the availability of efficient wind turbines of a few tens of kilowatt to multi-megawatt sizes which cover all human applications have made the utilization of wind power the technology of choice. For its optimal utilization, the site-dependent analysis of the wind and its variation with height and the economics of increasing the tower height (hub height) have become necessary factors. This paper proposes a new correlation for the estimation of optimal hub height for harnessing the power of the wind on an economically competitive basis. The optimal hub heights for Dhahran, Dhulom, Gassim, Juaymah and Rawdat Ben Habbas were found to be 64, 66, 81, 70 and 82 m, respectively. Furthermore, seven empirical correlations were developed for seven sites for wind turbines of rated power of 600 to 5000 kW. Wind speed measurements made at 20, 30 and 40 m at seven sites were used in the present work.