scholarly journals The influence of humidity fluxes on offshore wind speed profiles

2010 ◽  
Vol 28 (5) ◽  
pp. 1043-1052 ◽  
Author(s):  
R. J. Barthelmie ◽  
A. M. Sempreviva ◽  
S. C. Pryor
Keyword(s):  
Wind Speed ◽  
Wind Energy ◽  
Wind Turbine ◽  
Offshore Wind ◽  
Speed Profile ◽  
Relative Cost ◽  
Wind Speed Profile ◽  
Wind Speeds ◽  
Stable Conditions ◽  
Installed Capacity

Abstract. Wind energy developments offshore focus on larger turbines to keep the relative cost of the foundation per MW of installed capacity low. Hence typical wind turbine hub-heights are extending to 100 m and potentially beyond. However, measurements to these heights are not usually available, requiring extrapolation from lower measurements. With humid conditions and low mechanical turbulence offshore, deviations from the traditional logarithmic wind speed profile become significant and stability corrections are required. This research focuses on quantifying the effect of humidity fluxes on stability corrected wind speed profiles. The effect on wind speed profiles is found to be important in stable conditions where including humidity fluxes forces conditions towards neutral. Our results show that excluding humidity fluxes leads to average predicted wind speeds at 150 m from 10 m which are up to 4% higher than if humidity fluxes are included, and the results are not very sensitive to the method selected to estimate humidity fluxes.

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.

Wind Energy Perspectives in Myanmar

2020 ◽  
pp. 181-210
Author(s):  
Evgenii Ignatev ◽  
Galina Deryugina ◽  
Htet Myat Htoon ◽  
Mikhail Tyagunov
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
West Coast ◽  
Wind Farms ◽  
Offshore Wind ◽  
Optimal Composition ◽  
Construction Sites ◽  
Offshore Wind Farms ◽  
Installed Capacity ◽  
Energy Shortage

One of Myanmar's problems is energy shortage. Partially, energy shortage can possibly be decreased by the construction of sizeable grid-connected offshore wind farms. Eight prospective construction sites were selected and wind turbine models chosen. This chapter describes the method for determining the optimal composition of the wind farms complex, consisting of several offshore wind farms located at a considerable distance from each other in areas with significant wind regime asynchrony. To illustrate this method, the optimal composition with an installed capacity of 47.6 MW and located off Myanmar's west coast is defined.

The influence of the wind speed profile on wind turbine performance measurements

Wind Energy ◽  
2009 ◽  
Vol 12 (4) ◽  
pp. 348-362 ◽  
Author(s):  
Rozenn Wagner ◽  
Ioannis Antoniou ◽  
Søren M. Pedersen ◽  
Michael S. Courtney ◽  
Hans E. Jørgensen
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Speed Profile ◽  
Performance Measurements ◽  
Wind Speed Profile ◽  
Turbine Performance

Nonlinear Control of Variable Speed Wind Turbines With Switching Across Operating Regimes

2011 ◽  
Author(s):  
Tuhin Das ◽  
Greg Semrau ◽  
Sigitas Rimkus
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Equilibrium Points ◽  
Control Input ◽  
Variable Speed ◽  
Nonlinear Controller ◽  
Wind Speed Profile ◽  
Control Laws ◽  
Wind Speeds ◽  
Operating Regimes

One of the key control problems associated with variable speed wind turbine systems is maximization of energy extraction when operating below the rated wind speed and power regulation when operating above the rated wind speed. In this paper, we approach these problems from a nonlinear systems perspective. For below rated wind speeds we adopt existing work appearing in the literature and provide further insight into the characteristics of the resulting equilibrium points of the closed-loop system. For above rated wind speeds, we propose a nonlinear controller and analyze the stability property of the resulting equilibria. We also propose a method for switching between the two operating regimes that ensures continuity of control input at the transition point. The control laws are verified using a wind turbine model with a standard turbulent wind speed profile that spans both operating regimes.

scholarly journals Monitoring and Modeling Roof-Level Wind Speed in a Changing City

Atmosphere ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 87
Author(s):  
Kathrin Baumann-Stanzer ◽  
Sirma Stenzel ◽  
Gabriele Rau ◽  
Martin Piringer ◽  
Felix Feichtinger ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Energy ◽  
Wind Turbine ◽  
Urban Areas ◽  
Dispersion Model ◽  
Flow Direction ◽  
Energy Yield ◽  
Wind Speeds ◽  
Small Wind Turbine ◽  
Roof Level

Results of an observational campaign and model study are presented demonstrating how the wind field at roof-level in the urban area of Vienna changed due to the construction of a new building nearby. The investigation was designed with a focus on the wind energy yield of a roof-mounted small wind turbine but the findings are also relevant for air dispersion applications. Wind speed profiles above roof top are simulated with the complex fluid dynamics (CFD) model MISKAM (Mikroskaliges Klima- und Ausbreitungsmodell, microscale climate and dispersion model). The comparison to mast measurements reveals that the model underestimates the wind speeds within the first few meters above the roof, but successfully reproduces wind conditions at 10 m above the roof top (corresponding to about 0.5 times the building height). Scenario simulations with different building configurations at the adjacent property result in an increase or decrease of wind speed above roof top depending on the flow direction at the upper boundary of the urban canopy layer (UCL). The maximum increase or decrease in wind speed caused by the alternations in building structure nearby is found to be in the order of 10%. For the energy yield of a roof-mounted small wind turbine at this site, wind speed changes of this magnitude are negligible due to the generally low prevailing wind speeds of about 3.5 m s−1. Nevertheless, wind speed changes of this order could be significant for wind energy yield in urban areas with higher mean wind speeds. This effect in any case needs to be considered in siting and conducting an urban meteorological monitoring network in order to ensure the homogeneity of observed time-series and may alter the emission and dispersion of pollutants or odor at roof level.

Wind Energy Harnessing System for Low and High Wind Speeds

2019 ◽  
Author(s):  
Majid Rashidi ◽  
Jaikrishnan R. Kadambi ◽  
Renjie Ke
Keyword(s):  
Wind Speed ◽  
Wind Energy ◽  
Wind Turbine ◽  
High Speed ◽  
Power Transmission ◽  
Vertical Axis ◽  
Geographic Locations ◽  
Wind Speeds ◽  
Low Wind Speed ◽  
Energy Harnessing

Abstract This work presents the design and analysis of a novel wind energy harnessing system that makes use of wind defecting structures to increase the ambient wind speed at geographic locations with relatively low wind speed. The system however reacts to highspeed wind conditions by altering the profile of the wind defecting structure in order to eliminate wind speed amplification attribute of the system, thereby protecting the wind turbine assembly at high speed wind conditions. Although increasing the wind speed is advantageous at geographic locations that the wind speed is typically low; however, from times to time, there could be sustained high-speed wind conditions at the same locations that may damage the wind turbine systems that take advantage of the wind defecting structures. The present work disclosed a wind deflecting structure formed by at least two sail-like partial cylindrical structures that are supported atop of a tower-like foundation in a symmetric arrangement, where one or more wind turbines can be installed in the space between the two partial cylinders. The two partial cylinders, each substantially in form a quarter cylinder is made of plurality of parallel ribbed-like bars, hereafter referred to as “bars” with a flexible thin material that are mechanically supported by the bars. The bars are oriented in a direction perpendicular to the ground; allowing the wing deflecting structures to accept horizonal axis or vertical axis turbines in the space between them. The function of the bars is to allow the thin material, attached to them, to assume a curved configuration substantially in the form of a quarter cylinder. The apparatus is equipped with wind speed monitoring devices, and power source and power transmission means, such as cable-pulleys, chain-sprockets, gears, or mechanical linkages that all work in concert to deploy or stow the thin material along the vertical rods depending to the magnitude of the prevailing wind speed. Preliminary computational fluid dynamics analyses have shown that the wind deflecting structure proposed here in amplifies the wind speed by a factor of 1.65.

scholarly journals Aerodynamic Force and Comprehensive Mechanical Performance of a Large Wind Turbine during a Typhoon Based on WRF/CFD Nesting

2018 ◽  
Vol 8 (10) ◽  
pp. 1982 ◽  
Author(s):  
Shitang Ke ◽  
Wenlin Yu ◽  
Jiufa Cao ◽  
Tongguang Wang
Keyword(s):  
Wind Speed ◽  
Bearing Capacity ◽  
Wind Turbine ◽  
Aerodynamic Force ◽  
Ultimate Bearing Capacity ◽  
Wind Pressure ◽  
Dynamics Simulation ◽  
Speed Profile ◽  
Wind Speed Profile ◽  
Buckling Stability

Compared with normal wind, typhoons may change the flow field surrounding wind turbines, thus influencing their wind-induced responses and stability. The existing typhoon theoretical model in the civil engineering field is too simplified. To address this problem, the WRF (Weather Research Forecasting) model was introduced for high-resolution simulation of the Typhoon “Nuri” firstly. Secondly, the typhoon field was analyzed, and the wind speed profile of the boundary layer was fitted. Meanwhile, the normal wind speed profile with the same wind speed of the typhoon speed profile at the gradient height of class B landform in the code was set. These two wind speed profiles were integrated into the UDF (User Defined Function). On this basis, a five-MW wind turbine in Shenzhen was chosen as the research object. The action mechanism of speed was streamlined and turbulence energy surrounding the wind turbine was disclosed by microscale CFD (Computational Fluid Dynamics) simulation. The influencing laws of a typhoon and normal wind on wind pressure distribution were compared. Finally, key attention was paid to analyzing the structural response, buckling stability, and ultimate bearing capacity of the wind turbine system. The research results demonstrated that typhoons increased the aerodynamic force and structural responses, and decreased the overall buckling stability and ultimate bearing capacity of the wind turbine.

scholarly journals Doppler Lidar Investigations of Wind Turbine Near-Wakes and LES Modeling with New Porous Disc Approach

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2101
Author(s):  
Takanori Uchida ◽  
Tadasuke Yoshida ◽  
Masaki Inui ◽  
Yoshihiro Taniyama
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Farms ◽  
Wind Speeds ◽  
Wind Speed Distribution ◽  
Wake Model ◽  
Turbine Wake ◽  
Swept Area

Many bottom-mounted offshore wind farms are currently planned for the coastal areas of Japan, in which wind speeds of 6.0–10.0 m/s are extremely common. The impact of such wind speeds is very relevant for the realization of bottom-mounted offshore wind farms. In evaluating the feasibility of these wind farms, therefore, strict evaluation at wind speeds of 6.0–10.0 m/s is important. In the present study, the airflow characteristics of 2 MW-class downwind wind turbine wake flows were first investigated using a vertically profiling remote sensing wind measurement device (lidar). The wind turbines used in this study are installed at the point where the sea is just in front of the wind turbines. A ground-based continuous-wave (CW) conically scanning wind lidar system (“ZephIR ZX300”) was used. Focusing on the wind turbine near-wakes, the detailed behaviors were considered. We found that the influence of the wind turbine wake, that is, the wake loss (wind velocity deficit), is extremely large in the wind speed range of 6.0–10.0 m/s, and that the wake loss was almost constant at such wind speeds (6.0–10.0 m/s). It was additionally shown that these results correspond to the distribution of the thrust coefficient of the wind turbine. We proposed a computational fluid dynamics (CFD) porous disk (PD) wake model as an intermediate method between engineering wake models and CFD wake models. Based on the above observations, the wind speed range for reproducing the behavior of the wind turbine wakes with the CFD PD wake model we developed was set to 6.0–10.0 m/s. Targeting the vertical wind speed distribution in the near-wake region acquired in the “ZephIR ZX300”, we tuned the parameters of the CFD PD wake model (CRC = 2.5). We found that in practice, when evaluating the mean wind velocity deficit due to wind turbine wakes, applying the CFD PD wake model in the wind turbine swept area was very effective. That is, the CFD PD wake model can reproduce the mean average wind speed distribution in the wind turbine swept area.

scholarly journals Turbin angin poros vertikal tipe Savonius bertingkat dengan variasi posisi sudut

2016 ◽  
Vol 6 (2) ◽  
Author(s):  
I.B. Alit ◽  
Nurchayati Nurchayati ◽  
S.H. Pamuji
Keyword(s):  
Wind Speed ◽  
Wind Energy ◽  
Wind Turbine ◽  
Electric Power ◽  
Rotor Blade ◽  
Rotation Speed ◽  
Simple Construction ◽  
Wind Speeds ◽  
Turbine Performance ◽  
Low Wind Speeds

Wind turbine is a technology that converts wind energy to electric power. A Savonius type rotor blade is a simple wind turbine that operates on the concept of drag. The turbine has a potential to be developed as it has a simple construction and it is suitable for low wind speeds. Savonius rotor can be designed with two or three blades in single level or multi-levels. This research was conducted to obtain two levels wind turbine performance characteristics with variations in wind speed and different positions of angle on each level. The variations of the angle position of the wind turbine were 0°, 30°, 45°, 60°, and 90° in each stage. The result shows that the performance of the wind turbine is inversely to the degree of the angle position. The maximum rotation speed of the rotor was about 150.6 rpm that was generated at the wind speed of 5 m/s and the angle position of 0°. 

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