Wind Speed Area Research Articles

Adjustment of the summertime marine atmospheric boundary layer to the western Iberia coastal morphology

AbstractDuring summer (June, July, and August), northerly winds driven by the Azores anticyclone are prevalent over western Iberia. The Quick Scatterometer Satellite 2000 to 2009 summertime estimates reveal a broad high wind speed (≥7 ms−1) area extending about 300 km from shore and along the entire Iberian west coast. Nested in this large high‐speed region, preferred maximum regions anchored in the Iberian major capes, Finisterre, Roca, and S. Vicente, are found. Composite analyses of wind maxima were performed to diagnose the typical summertime synoptic‐scale pressure distribution associated with these smaller size high‐speed regions. The flow low‐level structure was further studied with a mesoscale numerical prediction model for three northerly events characterized by typical summertime synoptic conditions. A low‐level coastal jet, setting the background conditions to the marine atmospheric boundary layer (MABL) response to topography, was found in the three cases. The causes for wind maximum downwind capes were investigated, focusing on the hypothesis that western Iberia MABL responds to hydraulic forcing. For the three events supercritical and transcritical flow conditions were identified and expansion fan signatures were found downwind each cape. Aircraft measurements, performed during one of the events, gave additional evidence of the expansion fan leeward Cape Roca. The importance of other forcing mechanisms was also assessed by considering the hypothesis of downslope wind acceleration and found to be in direct conflict with soundings and surface observations.

Using artificial neural networks for temporal and spatial wind speed forecasting in Iran

Over the past few years, significant progress has been made in wind power generation worldwide. Because of the turbulent nature of wind velocity, the management of wind intermittence is a substantial field of research in the wind energy sector. This paper presents an investigation of this problem in two parts, the prediction of wind speed in both temporal and spatial dimensions, using artificial neural networks (ANNs). ANNs are novel methods applicable in modeling of complicated systems such as wind speed which generally investigated by a large amount of registered data exemplifying the behavior of.We first predicted the temporal dimension of wind speed at one-hour time interval, as a short-term wind speed prediction, in three wind observation stations (WOSs) in Iran. In the next part, estimation of wind speed data in a WOS using data from some other nearby WOSs was carried out. Due to the limitation of data collection, two groups of WOSs were selected for this target. The average value of the wind speed histogram error obtained from the best model in both groups is about 2.6% which is certainly promising.In Iran, the scarcity of meteorological data has resulted in the limited study of wind energy resources. Therefore, this type of spatial prediction is very useful in wind resource assessment in the Iranian wind energy industry. This is a valuable tool that enables the decision maker to precisely detect the high wind speed areas over an entire region in the first step of investigation.

Experimental Determination of Wind Flowing around a Building Configuration

This paper deals with a solution of air flow around the group of structures. Boundary layer for urban terrain was simulated in BLWT STU wind tunnel. The series of flow characteristics were investigated with boundary layer for the urban terrain, which was simulated with rough elements and barriers of different heights. Experimental results presented as mean velocity, turbulence intensity, integral length scale of turbulence and power spectral density were compared with [1] and ESDU data. Wind environment studies around idealized building and building configurations were carried out with the major focus on flow caused by strong wind with different directions. In this research, a series of parametric wind tunnel studies was carried out to investigate the effects of building width, height and the building configurations on the wind pressure distribution [2,3 and 4]. In the article, we will discuss this issue for atypical building configuration in the center of Bratislava. We will indicate the high wind speed areas for strong wind conditions and try to find optimal solutions in terms of the planned groups of new buildings. The wind pressure distribution on the structures is an important parameter in terms of wind load calculation.

Micro-Turbine Design, Production and Testing

Large scale utilization of electricity started at the end of 19th century with the construction first power plant and there phase current was introduced. Power plant technology evolved rapidly and electricity use has increased rapidly since then. Outbreak of energy crisis in 1970s and threat of the global warming has forced the people to search clean energy resources. Among the renewable energy sources, wind energy has become the most popular case. Development of the necessary technology for wind turbines reached a commercial competence In the 1990s. Turning to wind energy in Turkey began after 2006 and has shown a rapid increase until 2015. When considering the country's wind potential it tends to stay in rapid growth. In this study, 2 kW micro-turbines is designed, manufactured and tested by using local facility. The aim of this study is to design a micro-turbine for use in low wind speed area, create industrial infrastructure related to the production of micro-turbine, and develop different production technologies for local industry.

Experimental investigations of fabric material against projectile impacts

Air supported structures made of PVC coated polyester fabric materials have been used in industrial and commercial building constructions. If they are used in cyclonic regions, the structure envelop might be impacted by windborne debris. The windborne debris might perforate the fabric material, which not only results in total collapse of the structure, flying debris at high speed also imposes threats to people and facilities inside the structure. In this study, the penetration resistant capability of PVC coated polyester fabric material commonly used in air supported structures construction was tested by using a pneumatic cannon system. The impact loading from windborne debris equivalent to a timber projectile of 4kg mass as specified in the Australian Wind Loading Code (AS/NZS 1170.2:2011) was applied in the test. The failure and damage modes under various projectile impact scenarios were observed and compared. Its capability of resisting projectile impact was assessed. The performances of PVC coated polyester fabric material were examined quantitatively in terms of projectile residual velocity and energy absorption. The effects of various projectile velocity, impact location, fabric pretension and boundary condition on their penetration resistance performance were studied. The testing results will benefit construction designers involved in the fabric material applications in high wind speed area.

Dynamic response improvement of hybrid system by implementing ANN-GA for fast variation of photovoltaic irradiation and FLC for wind turbine

Abstract In this paper, dynamic response improvement of the grid connected hybrid system comprising of the wind power generation system (WPGS) and the photovoltaic (PV) are investigated under some critical circumstances. In order to maximize the output of solar arrays, a maximum power point tracking (MPPT) technique is presented. In this paper, an intelligent control technique using the artificial neural network (ANN) and the genetic algorithm (GA) are proposed to control the MPPT for a PV system under varying irradiation and temperature conditions. The ANN-GA control method is compared with the perturb and observe (P&O), the incremental conductance (IC) and the fuzzy logic methods. In other words, the data is optimized by GA and then, these optimum values are used in ANN. The results are indicated the ANN-GA is better and more reliable method in comparison with the conventional algorithms. The allocation of a pitch angle strategy based on the fuzzy logic controller (FLC) and comparison with conventional PI controller in high rated wind speed areas are carried out. Moreover, the pitch angle based on FLC with the wind speed and active power as the inputs can have faster response that lead to smoother power curves, improving the dynamic performance of the wind turbine and prevent the mechanical fatigues of the generator

A preliminary energy and environmental assessment of a micro wind turbine prototype in natural protected areas

This paper presents a preliminary energy and environmental analysis of a vertical-axis micro wind turbine with a nominal electric power of 3.7kW. This prototype is called AM300.The main aim of the paper is to assess the amount of electric energy production of the AM300 and its feasible use in low wind speed areas. Furthermore, analyzing its low environmental impact, a potential installation in a natural protected area was considered.The turbine power curve was estimated by anemometric measurements. Furthermore, foreseeable prototype hybridization with PV array was analyzed.The environmental performance was assessed evaluating the soil, hydro geological, biodiversity and noise impacts. Finally, an analysis of the CO2 emissions avoided is reported. The obtained results show good sustainability perspectives.

Overview and Design of self-acting pitch control mechanism for vertical axis wind turbine using multi body simulation approach

Awareness about wind energy is constantly growing in the world. Especially a demand for small scale wind turbine is increasing and various products are available in market. There are mainly two types of wind turbines, horizontal axis wind turbine and vertical axis wind turbines. Horizontal axis wind turbines are suitable for high wind speed whereas vertical axis wind turbines operate relatively low wind speed area. Vertical axis wind turbines are cost effective and simple in construction as compared to the horizontal axis wind turbine. However, vertical axis wind turbines have inherent problem of self-start inability and has low power coefficient as compare to the horizontal axis wind turbine. These two problems can be eliminated by incorporating the blade pitching mechanism. So, in this paper overview of various pitch control systems is discussed and design of self-acting pitch mechanism is given. A pitch control linkage mechanism for vertical axis wind turbine is modeled by multi-body approach using MSC Software. Aerodynamic loads are predicted from a mathematical model based on double multiple stream tube method. An appropriate airfoil which works at low Reynolds number is selected for blade design. It is also focused on commercialization of the vertical axis wind turbine which incorporates the self-acting pitch control system. These aerodynamic load model will be coupled with the multi-body model in future work for optimization of the pitch control linkage mechanism. A 500 Watt vertical axis wind turbine is designed and it is planned to implement the self-acting pitch control mechanism in real model.

Power Curve of a Wind Generator Suitable for a Low Wind Speed Site to Achieve a High Capacity Factor

It is well known that energy generated by a wind generator (WG) depends on the wind resources at the installation site. In other words, a WG installed in a high wind speed area can produce more energy than that in a low wind speed area. However, a WG installed at a low wind site can produce a similar amount of energy to that produced by a WG installed at a high wind site if the WG is designed with a rated wind speed corresponding to the mean wind speed of the site. In this paper, we investigated the power curve of a WG suitable for Korea's southwestern coast with a low mean wind speed to achieve a high capacity factor (CF). We collected the power curves of the 11 WGs of the 6 WG manufacturers. The probability density function of the wind speed on Korea's southwestern coast was modeled using the Weibull distribution. The annual energy production by the WG was calculated and then the CFs of all of the WGs were estimated and compared. The results indicated that the WG installed on the Korea's southwestern coast could obtain a CF higher than 40 % if it was designed with the lower rated speed corresponding to the mean wind speed at the installation site.

PERFORMANCE ANALYSIS OF VARIOUS PARAMETERS BY COMPARISON OF CONVENTIONAL PITCH ANGLE CONTROLLER WITH FUZZY LOGIC CONTROLLER

This paper deals with a variable speed wind turbine coupled with a permanent magnet synchronous generator connected through a two mass drive train. This drive train is connected to synchronous generator and after the conversion process finally connected to grid and the idea of transmission over a long distance makes the use of converter necessary and at the receiving end. The inverter is used to convert it back and the inverter is designed with a proper gate signal to get the best output three phase voltages. The fuzzy logic controller is used to track generator speed with varying wind speed to optimize turbine aerodynamic efficiency in the outer speed loop. Pitch angle control of wind turbine has been used widely to reduce torque and output power variation in high rated wind speed areas .The machine side converter is designed to extract maximum power from the wind. In this work a WECS connected with grid is designed in Matlab and a Fuzzy controller is designed to improve the output and we can see the major difference in DC link voltage and reactive power in transmission line. From the outputs we can also go through the reactive power issue which system is best for inductive load or capacitive load. The simple PI system is good for capacitive load and the fuzzy system is better option for the inductive load. The results of both the system of normal controller and fuzzy controller is compared and analyzed.

CSP and PV Solar Tracker Optimization Tool

The support structure of CPV and PV trackers and heliostats are one of the most important cost elements of a solar plant because they typically contribute of ∼20% - ∼30% to the total cost of the system. Consequently, it is important to reduce the cost of solar trackers or heliostats as much as possible to improve the economic viability of a solar plant.In this paper, a new method is presented for optimizing trackers with arbitrary design and geometry. It is based on linear optimization and implemented as a custom-built finite element library, developed by the author. The user can choose from a set of configurable tracker geometries, which is extensible by arbitrary tracker geometries defined using a text file, and let the software optimize the amount of steel required for the support structure. Stress and buckling (lateral and local) validations are performed in conformity to Eurocode EN 1993-1-1 - Design of steel structures. Wind load assumptions are taken from the wind tunnel studies of Peterka and Derickson and applied as non uniform load distributions on the tracker surface. Additional national standards can be considered by setting appropriate safety factors for wind and dead load.In summary, this software represents a powerful tool for optimizing and performing a preliminary design of CSP and PV structures with the potential to reduce developing times significantly. The results of the performed investigation could be used to determine the specific weight of a tracker in kg/m2 as a function of the wind speed and tracker area with respect of the tracker aspect ratio.

Performance Testing and Dimensional Analysis of Multi-Blade Wind Turbine for Low Wind Speed Applications

This article is to present the study results of small multi blade wind turbine for use in low wind speed area. In this experiment, the wind turbine has a diameter is 1 m, 30 blades. Each blade has the chord length of 6.5 cm, the length of 0.25 m, which has a curvature plate ratio of 0.15, and blade setting angle of 30 degree. Wind turbine was tested by wind tunnel at wind velocity of 3, 4 and 5 m/s. The results from the test run of, this the wind turbine give maximum mechanical power in each wind velocity of 3.66, 9.91 and 21.76 watts, respectively. From the dimensional analysis of wind rotor turbine by using Buckingham Pi theorem, the wind turbine is up to two times as large that is 2 m diameter; give maximum mechanical power increased to 14.64, 39.24 and 87.04 watts, this power can be generate electric power or use for water pumping for a household.

Numerical study on the impacts of the bogus data assimilation and sea spray parameterization on typhoon ducts

The Weather Research and Forecasting model version 3.2 (WRF v3.2) was used with the bogus data assimilation (BDA) scheme and sea spray parameterization (SSP), and experiments were conducted to assess the impacts of the BDA and SSP on prediction of the typhoon ducting process induced by Typhoon Mindule (2004). The global positioning system (GPS) dropsonde observations were used for comparison. The results show that typhoon ducts are likely to form in every direction around the typhoon center, with the main type of ducts being elevated duct. With the BDA scheme included in the model initialization, the model has a better performance in predicting the existence, distribution, and strength of typhoon ducts. This improvement is attributed to the positive effect of the BDA scheme on the typhoon’s ambient boundary layer structure. Sea spray affects typhoon ducts mainly by changing the latent heat (LH) flux at the air-sea interface beyond 270 km from the typhoon center. The strength of the typhoon duct is enhanced when the boundary layer under this duct is cooled and moistened by the sea spray; otherwise, the typhoon duct is weakened. The sea spray induced changes in the air-sea sensible heat (SH) flux and LH flux are concentrated in the maximum wind speed area near the typhoon center, and the changes are significantly weakened with the increase of the radial range.

Comparison of Energy Yield of Small Wind Turbines in Low Wind Speed Areas

The objective of this paper is to compare the energy yield and generated electricity cost of several commercially available small wind turbines under low wind speed condition. Many small wind turbines were not able to generate the amount of electricity promised by the manufacturers. The predicted annual energy yield simulated using manufacturers' power curve were sometimes higher than actual measured values by up to a factor of two. Furthermore, above a rotor size of 3 m, large diameter turbines performed better, having both low generated electricity cost ( € /kWh) and high annual energy yield per swept area (kWh/m 2).

Computationally Inexpensive Approach for Pitch Control of Offshore Wind Turbine on Barge Floating Platform

Offshore floating wind turbine (OFWT) has gained increasing attention during the past decade because of the offshore high-quality wind power and complex load environment. The control system is a tradeoff between power tracking and fatigue load reduction in the above-rated wind speed area. In allusion to the external disturbances and uncertain system parameters of OFWT due to the proximity to load centers and strong wave coupling, this paper proposes a computationally inexpensive robust adaptive control approach with memory-based compensation for blade pitch control. The method is tested and compared with a baseline controller and a conventional individual blade pitch controller with the “NREL offshore 5 MW baseline wind turbine” being mounted on a barge platform run on FAST and Matlab/Simulink, operating in the above-rated condition. It is shown that the advanced control approach is not only robust to complex wind and wave disturbances but adaptive to varying and uncertain system parameters as well. The simulation results demonstrate that the proposed method performs better in reducing power fluctuations, fatigue loads and platform vibration as compared to the conventional individual blade pitch control.

Case Study of a Barrier Wind Corner Jet off the Coast of the Prince Olav Mountains, Antarctica

AbstractThe Ross Ice Shelf airstream (RAS) is a barrier parallel flow along the base of the Transantarctic Mountains. Previous research has hypothesized that a combination of katabatic flow, barrier winds, and mesoscale and synoptic-scale cyclones drive the RAS. Within the RAS, an area of maximum wind speed is located to the northwest of the protruding Prince Olav Mountains. In this region, the Sabrina automatic weather station (AWS) observed a September 2009 high wind event with wind speeds in excess of 20 m s−1 for nearly 35 h. The following case study uses in situ AWS observations and output from the Antarctic Mesoscale Prediction System to demonstrate that the strong wind speeds during this event were caused by a combination of various forcing mechanisms, including katabatic winds, barrier winds, a surface mesocyclone over the Ross Ice Shelf, an upper-level ridge over the southern tip of the Ross Ice Shelf, and topographic influences from the Prince Olav Mountains. These forcing mechanisms induced a barrier wind corner jet to the northwest of the Prince Olav Mountains, explaining the maximum wind speeds observed in this region. The RAS wind speeds were strong enough to induce two additional barrier wind corner jets to the northwest of the Prince Olav Mountains, resulting in a triple barrier wind corner jet along the base of the Transantarctic Mountains.

Sand erosion technique applied to wind resource assessment

One of the major challenges of the wind energy sector is to accurately predict the wind potential. This task is especially difficult in mountainous terrains where the topography can imply complex relief-induced flows. Wind tunnel testing is one of the possibilities to simulate and predict the wind for wind turbine micro-siting. Most advanced quantitative measurement techniques can be used in the wind tunnel, however, measuring the whole terrain to find the highest wind potential zones is very time-consuming. This paper proposes to use a very simple, quick and cheap technique to detect and evaluate the high wind speed areas over an entire model. Commonly used for pedestrian wind comfort assessment, the sand erosion technique is here applied to wind resource assessment. The technique can provide valuable qualitative information but can also give an order of magnitude of the local speed-up. It is first applied to a backward facing step flow and then on a mountainous terrain. An amplification factor and the fractional speed-up ratio (FSR) can be calculated over the entire mountain. For high speed positions results extracted from sand erosion appears to be comparable the one calculated by particle image velocimetry. The technique is repeatable, able to perform a detection of the high speed area, and capable of giving an estimation of the amplitude of the wind. The technique allows to restrict the use of quantitative measurements to the most interesting areas.

Wind effects on trees

The interactions between airflow and trees and forest stands are diverse. They include the reduction in nearsurface wind speed and production of turbulence by trees. Near-surface wind conditions affect physiological processes in trees, tree growth, and survival (Ennos 1997; Eugster 2008). Turbulent components of the flow field dominate the tree response behaviour (Mayer 1987; Gardiner 1995; Schindler et al. 2010) and drive the scalar exchange at the forest–atmosphere interface (Finnigan 2000). Wind–tree interactions take place at a wide range of temporal and spatial scales (de Langre 2008). Aerodynamic drag at all surfaces of the aerial parts of trees—from individual leaves (Vogel 1989) to whole tree crowns (Kane et al. 2008)—perturbs the airflow inside forest canopies (Shaw et al. 1974; Baldocchi and Meyers 1988; Turnipseed et al. 2003). Therefore, detailed information on forest structure is an essential precondition for understanding wind–tree interactions and the successful application of flow models to tall canopies. In flow models, forest structure is often represented by the mean vertical profile of the plant area density. Queck et al. (2011, this issue) present a method that can be used to record detailed 3D stand structure from terrestrial laser scanning. They investigated the relationship between wind speed, aerodynamic drag, and plant area density and show how 3D laser scanner data can be used to derive turbulence parameters for flow models. The structure of windward forest edges (Mitscherlich 1973; Dupont and Brunet 2008a, b) as well as the stand structure (Gardiner et al. 1997; Marcolla et al. 2003; Dupont and Brunet 2008b, c; Queck and Bernhofer 2010) affects the flow field within and above forests. In the nearedge region, pronounced gradients of flow quantities provoke high wind load on trees (Stacey et al. 1994; Peltola 1996; Gardiner et al. 1997), which may trigger damage in strong wind conditions. Although Gardiner and Stacey (1996) as well as Dupont and Brunet (2008a) report that tapered forest edges reduce wind loading and related bending moments of trees near the edge, it is still not completely clear, how changes in edge and stand structure affect the flow field at the canopy near forest edges, and whether these changes can contribute to the mitigation of damage in high wind conditions. In a detailed wind tunnel study, Ruck et al. (2011, this issue) investigated the effect of changes in taper angle of windward forest edges on the flow field for different stand densities. Their results demonstrate the impact of edge shape and stand density on quantities of the flow field near the canopy top, the region most relevant for tree failure in strong wind conditions. The aerial parts of trees start to vibrate in response to wind excitation (Sellier and Fourcaud 2005; Rodriguez et al. 2008). In forests, dynamic tree responses are not only observed at the single tree level (Mayer 1987; Gardiner 1995; Peltola 1996; Flesch and Wilson 1999; Rudnicki et al. 2008; Schindler et al. 2010) but also at the tree group level (Rudnicki et al. 2001, 2003; Schindler et al. 2011, this issue). At both levels, the resulting tree response patterns are complex and complicated. So far, even in horizontally homogeneous terrain, not all physical and biological This article belongs to the special issue ‘Wind Effects on Trees’.

Optimizing Design of Direct Air-Cooled Condenser

The optimizing design approach of direct air-cooled system was described in detail in this paper. Based on the approach, the wind speed, ambient temperature and heat transfer area of air-cooled condenser were considered to meet the design parameters and the rated power. The optimizing results and economic analysis were discussed.

Wind tunnel study of pedestrian level wind environment around tall buildings: Effects of building dimensions, separation and podium

It is well known that high-rise buildings affect the surrounding pedestrian level wind environment. In recent years, awareness and concern has increased about the creation of low wind speed areas around tall buildings which may lead to poor out-door air ventilation. In addition, new building developments are often not restricted to a single building, but comprise a row of buildings, which may have complex plan-forms, and some integrating an extensive podium. This paper aims at providing a fundamental understanding of wind–structure interactions that govern the effects of building dimensions and separations, a row of buildings and podium on the pedestrian level wind environment, for both weak and strong wind conditions, by a series of parametric wind tunnel studies. The study area covered an extensive area which covered up to 400 m downstream of the test buildings. The results show that a single wider building created adverse effects on the natural air ventilation at pedestrian level around the building while a taller building improved the near-field air ventilation conditions. In the studies of building separation effects, the results show an adverse effect on natural air ventilation at pedestrian level when the building separations are less than half the building width. Inclusion of a podium was also found to adversely affect the air movement around buildings.