Gust Wind Speed Research Articles

Wintersturmschäden im Schweizer Wald von 1865 bis 2014

Forest damages from winter storms in Switzerland from 1865 to 2014 Winter storms cause the most catastrophic damages in Swiss forests. The present article analyses how these storm damages correspond with wind gust speed, growing stock and forest area, in regard to the whole country and individual cantons, and from 1865 to 2014. During the study period, 26 storm events each totalling a volume of at least 70,000 m3 damaged wood were registered. Winter storm damages were highly variable regarding absolute numbers (volume) and portions per area (m3 per ha) and per growing stock (%). In the past 150 years, the cantons Nidwalden, Freiburg, Aargau, Zurich and Zug were hit most often by storm events, with damages ranging per event in average from 2.2 m3 per ha (Zurich) to 3.1 m3 per ha (Nidwalden). At the turn of the millennium, not only the greatest damages occurred but also growing stock peaked as well did the wind gust speeds.

A Probabilistic Framework for Prioritizing Wood Pole Inspections Given Pole Geospatial Data

Managing the widely distributed wood pole assets owned by typical electric power utilities in the USA is challenging in the absence of appropriate analytical tools. The traditional method of inspecting poles by headquarters or strictly age is insufficient for effective management since natural hazards cause the largest instantaneous pole replacements. A probabilistic framework is developed and presented in this paper to address this issue. Fragility assessment is conducted using Latin hypercube sampling to estimate pole failure probabilities conditional on wind speed intensities. Failure probability estimates are obtained using age-dependent fragility functions and appropriate distribution functions for maximum 3 s wind gust speeds. Pole locations from an electric power utility’s database management system were imported into ArcMap, a component of Environmental Systems Research Institute geospatial processing program. Age distributions were extracted by county and used to estimate expected pole failures. A sort-algorithm on the failures—the inspection order indices gives the proposed appropriate order of pole locations to be inspected. These calculated values were added as a data layer into ArcMap generating a geospatial visualization of both the orders of pole inspections and probabilistic pole loss estimates for the electric utility by counties. Applying the framework will increase utilities’ visibility into the vulnerability of their pole plants. Emergency preparedness will also improve, strengthening customer-perception on utilities’ maintenance efforts.

Effects of pressure angle and tip relief on the life of speed increasing gearbox: a case study.

This paper examines failure of helical gear in speed increasing gearbox used in the wind turbine generator (WTG). In addition, an attempt has been made to get suitable gear micro-geometry such as pressure angle and tip relief to minimize the gear failure in the wind turbines. As the gear trains in the wind turbine gearbox is prearranged with higher speed ratio and the gearboxes experience shock load due to atmospheric turbulence, gust wind speed, non-synchronization of pitching, frequent grid drops and failure of braking, the gear failure occurs either in the intermediate or high speed stage pinion. KISS soft gear calculation software was used to determine the gear specifications and analysis is carried out in ANSYS software version.11.0 for the existing and the proposed gear to evaluate the performance of bending stress tooth deflection and stiffness. The main objective of this research study is to propose suitable gear micro-geometry that is tip relief and pressure angle blend for increasing tooth strength of the helical gear used in the wind turbine for trouble free operation.Electronic supplementary materialThe online version of this article (doi:10.1186/2193-1801-3-746) contains supplementary material, which is available to authorized users.

Effect of weather on back pain: results from a case-crossover study.

To investigate the influence of various weather conditions on risk of low back pain. We conducted a case-crossover study in primary care clinics in Sydney, Australia. A total of 993 consecutive patients with a sudden, acute episode of back pain were recruited from October 2011 to November 2012. Following the pain onset, demographic and clinical data about the back pain episode were obtained for each participant during an interview. Weather parameters (temperature, relative humidity, air pressure, wind speed, wind gust, wind direction, and precipitation) were obtained from the Australian Bureau of Meteorology for the entire study period. Weather exposures in the case window (time when participants first noticed their back pain) were compared to exposures in 2 control time windows (same time duration, 1 week and 1 month before the case window). Temperature, relative humidity, air pressure, wind direction, and precipitation showed no association with onset of back pain. Higher wind speed (odds ratio [OR] 1.17 [95% confidence interval (95% CI) 1.04-1.32], P = 0.01 for an increase of 11 km/hour) and wind gust (OR 1.14 [95% CI 1.02-1.28], P = 0.02 for an increase of 14 km/hour) increased the odds of pain onset. Weather parameters that have been linked to musculoskeletal pain such as temperature, relative humidity, air pressure, and precipitation do not increase the risk of a low back pain episode. Higher wind speed and wind gust speed provided a small increase in risk of back pain, and although this reached statistical significance, the magnitude of the increase was not clinically important.

Intense and Extreme Wind Speeds Observed by Anemometer and Seismic Networks: An Eastern U.S. Case Study

AbstractThe scale and intensity of extreme wind events have tremendous relevance to determining the impact on infrastructure and natural and managed ecosystems. Analyses presented herein show the following. 1) Wind speeds in excess of the station-specific 95th percentile are coherent over distances of up to 1000 km over the eastern United States, which implies that the drivers of high wind speeds are manifest at the synoptic scale. 2) Although cold fronts associated with extratropical cyclones are a major cause of high–wind speed events, maximum sustained and gust wind speeds are only weakly dependent on the near-surface horizontal temperature gradient across the front. 3) Gust factors (GF) over the eastern United States have a mean value of 1.57 and conform to a lognormal probability distribution, and the relationship between maximum observed GF and sustained wind speed conforms to a power law with coefficients of 5.91 and −0.499. Even though there is coherence in the occurrence of intense wind speeds at the synoptic scale, the intensity and spatial extent of extreme wind events are not fully characterized even by the dense meteorological networks deployed by the National Weather Service. Seismic data from the USArray, a program within the Earthscope initiative, may be suitable for use in mapping high-wind and gust events, however. It is shown that the seismic channels exhibit well-defined spectral signatures under conditions of high wind, with a variance peak at frequencies of ~0.04 s−1 and an amplitude that appears to scale with the magnitude of observed wind gusts.

Gust durations, gust factors and gust response factors in wind codes and standards

This paper discusses the appropriate duration for basic gust wind speeds in wind loading codes and standards, and in wind engineering generally. Although various proposed definitions are discussed, the 'moving average' gust duration has been widely accepted internationally. The commonly-specified gust duration of 3-seconds, however, is shown to have a significant effect on the high-frequency end of the spectrum of turbulence, and may not be ideally suited for wind engineering purposes. The effective gust durations measured by commonly-used anemometer types are discussed; these are typically considerably shorter than the 'standard' duration of 3 seconds. Using stationary random process theory, the paper gives expected peak factors, g w, as a function of the non-dimensional parameter (T/τ), where T is the sample, or reference, time, and τ is the gust duration, and a non-dimensional mean wind speed, U. T/L w, where U is a mean wind speed, and L w is the integral length scale of turbulence. The commonly-used Durst relationship, relating gusts of various durations, is shown to correspond to a particular value of turbulence intensity I u, of 16.5%, and is therefore applicable to particular terrain and height situations, and hence should not be applied universally. The effective frontal areas associated with peak gusts of various durations are discussed; this indicates that a gust of 3 seconds has an equivalent frontal area equal to that of a tall building. Finally a generalized gust response factor format, accounting for fluctuating and resonant along-wind loading of structures, applicable to any code is presented.

Investigation of time and weather effects on crash types using full Bayesian multivariate Poisson lognormal models

Previous research shows that various weather elements have significant effects on crash occurrence and risk; however, little is known about how these elements affect different crash types. Consequently, this study investigates the impact of weather elements and sudden extreme snow or rain weather changes on crash type. Multivariate models were used for seven crash types using five years of daily weather and crash data collected for the entire City of Edmonton. In addition, the yearly trend and random variation of parameters across the years were analyzed by using four different modeling formulations. The proposed models were estimated in a full Bayesian context via Markov Chain Monte Carlo simulation. The multivariate Poisson lognormal model with yearly varying coefficients provided the best fit for the data according to Deviance Information Criteria. Overall, results showed that temperature and snowfall were statistically significant with intuitive signs (crashes decrease with increasing temperature; crashes increase as snowfall intensity increases) for all crash types, while rainfall was mostly insignificant. Previous snow showed mixed results, being statistically significant and positively related to certain crash types, while negatively related or insignificant in other cases. Maximum wind gust speed was found mostly insignificant with a few exceptions that were positively related to crash type. Major snow or rain events following a dry weather condition were highly significant and positively related to three crash types: Follow-Too-Close, Stop-Sign-Violation, and Ran-Off-Road crashes. The day-of-the-week dummy variables were statistically significant, indicating a possible weekly variation in exposure. Transportation authorities might use the above results to improve road safety by providing drivers with information regarding the risk of certain crash types for a particular weather condition.

Developing predictive models of wind damage in Austrian forests

Among natural disturbances, wind storms cause the greatest damage to forests in Austria. The aim of this study is to quantify the effects of site, stand and meteorological attributes on the wind disturbance regime at the operational scale of forest stands. We used binomial generalized linear mixed models (GLMMs) to quantify the probability of damage events and linear mixed models (LMMs) to explain the damage intensity at the forest stand level in four management units with a total forest area of approximately 28,800 ha. Timber stock volume, stand age, elevation, previous disturbances, wind gust speed and frozen state of soil contributed in explaining probability of wind damage. While the model of disturbance probability correctly classified 90 % of all cases in the data set (specificity 95 %, sensitivity 26 %), the model for damage intensity explained only low percentages of the variation in the observed damage data (full model R 2 = 0.38, fixed effects-only model R 2 = 0.09; cross-validation in the four forest management units yielded similar R 2 values). The developed models indicated that decreasing the proportion of Norway spruce (Picea abies [L.] Karst), limiting stand age and reducing the timber stock in course of tending treatments in stands exposed to wind disturbance can mitigate the risk and the expected damage intensity. High gust speeds and salvage cuts after earlier damage increase the probability of further wind disturbance events.

From the Editors

From the Editors

Wind Turbine and Photovoltaic Hybrid Generations under Extreme Operating Gust

A micro-grid consisting of a 300kW wind turbine and a 40kW photovoltaic array is investigated under extreme operating gust (EOG) wind scenarios. The micro-grid is connected to the 380-V utility through a utility-side converter using natural-frame control, which provides a constant voltage of the DC link between the micro-grid and utility. The impact of the extreme gust wind variations on the micro-grid performance is studied for variable speed wind energy system equipped with a squirrel-cage induction generator. The Hurghada city, Red Sea, Egypt is taken as a case study for the wind speed profile. A detailed model of extreme gust-wind speed variation is implemented and simulated using PSIM commercial software package, based on climate characteristics of Hurghada city. The indirect rotor field oriented control (FOC) method is implemented to the generator-side converter to keep the system stable under the extreme gust wind conditions and to control the squirrel-cage induction generator (SCIG) speed for maximum power-point tracker (MPPT) regime. Power quality of the utility-side converter in terms of operation at different power factors, voltage value and THD are verified.

Evidence from the Historical Record to Support Projection of Future Wind Regimes: An Application to Canada

ABSTRACTIn the field of climate change impact analysis, bidirectional changes in projections of future wind regimes varying among studies, locations, and models have been described in the literature, which is understandable from a global perspective. However, we should attempt to find evidence in the historical record to support these projections. This paper attempts to address this issue by analyzing historical wind gust observations for up to 57 years (1953–2009) over Canada. Two wind gust analysis techniques were used: the speed of daily wind gust events ≥50 km h−1 was compared with (1) the climatological daily temperature anomaly and (2) the climatological daily sea level air pressure anomaly. In addition, the frequency of daily wind gust events ≥90 km h−1 was compared with both daily temperature and pressure anomalies. The results indicate that during the past five decades gust wind speed over Canada increased significantly as the daily temperature anomaly increased and the daily pressure anomaly decreased. About 50–60% of daily wind gust events ≥90 km h−1 occurred with positive daily temperature anomalies and negative daily pressure anomalies. One major conclusion is that the methods used in and results derived from this study might be applied to climate change impact analysis to support projections of future wind regimes.

An extensive evaluation of wind resource using new methods and strategies for development and utilizing wind power in Mah-shahr station in Iran

In this study, the 10-min period measured short-term wind speed data at 10m and 40m heights for Mah-shahr station in Iran was statistically analyzed to determine the potential of wind power generation. In addition in this paper different distribution functions are compared to each other in order to find the best distribution in Mah-shahr which is compatible with the wind data. It is found that the Weibull distribution is the best function to model the wind data in Mah-shahr. It should also be mentioned that the different methods for calculating Weibull parameters were used and compared to each other. Moreover an extreme analysis of wind data in Mah-shahr was carried out to determine the maximum gust wind speed over a 50-year return period (Ve50). Using the method of “periodic maxima” for analysis of extreme winds, it was revealed that the 50-year wind speed at 80m in Mah-shahr which is 39.5m/s is lower than usual values of Ve50 limits for different wind turbines. This means that the risk of extreme wind gusts in Mah-shahr might not be a problem for installation of wind turbines. From the primary evaluation of wind data in Mah-shahr it is found the studied site has an acceptable potential of wind power for electricity generation. Energy production of different wind turbines at different heights is determined. Then a simple economic evaluation carried out to determine whether studied site is suitable for development of commercial or small and residential wind turbines. It became clear that the “Nordex N100/2500” with a rated power of 2500kW has the lowest price of electricity and has a high level of capacity factor. Thus in the second phase of the study an extensive economic evaluation of installing 10MW wind park using 4 Nordex N100/2500 wind turbines was performed on the RETScreen® international simulation software. For this purpose, four main scenarios have been taken into consideration. It was revealed that in the second scenario by assumption of the new proposed feed-in-tariff rate (4400 rials), the return period of investment was significantly reduced. It has been demonstrated that the government’s new policy for increasing the feed-in-tariff rate has been very effective for improving the financial viability of the proposed wind farm. In the final steps, effects of the clean development strategies have been taken into account.

Wind Loads on a Medium-Rise Building by Using Five Major International Wind Codes and Standards

Wind load calculations are done for a medium-rise building with 48 m height locates in an urban area of Sri Lanka. Five different international wind loading standards were selected to calculate wind loads according to prevailing conditions in Sri Lanka. Available 3 second gust wind speed is converted in to mean hourly wind speed and 10 minutes average wind speed to use selected wind loading standards. The difference of wind load calculations is evaluated by using member forces in columns, beams, and shear walls obtained from a 3–D finite element modelling. The comparison displays that both the Australian standards yields higher wind loads compared to other selected standards. The use of higher terrain-height multiplier for cyclone prone zone 1 contributes much larger member forces compared to other cases. None of the standards exceeds the serviceability criteria, which evaluate by means of drift index. ENGINEER, Vol. 47, No. 01, pp. 25-35, 2014

Can dynamically downscaled windstorm footprints be improved by observations through a probabilistic approach?

AbstractWindstorms are a main feature of the European climate and exert strong socioeconomic impacts. Large effort has been made in developing and enhancing models to simulate the intensification of windstorms, resulting footprints, and associated impacts. Simulated wind or gust speeds usually differ from observations, as regional climate models have biases and cannot capture all local effects. An approach to adjust regional climate model (RCM) simulations of wind and wind gust toward observations is introduced. For this purpose, 100 windstorms are selected and observations of 173 (111) test sites of the German Weather Service are considered for wind (gust) speed. Theoretical Weibull distributions are fitted to observed and simulated wind and gust speeds, and the distribution parameters of the observations are interpolated onto the RCM computational grid. A probability mapping approach is applied to relate the distributions and to correct the modeled footprints. The results are not only achieved for single test sites but for an area‐wide regular grid. The approach is validated using root‐mean‐square errors on event and site basis, documenting that the method is generally able to adjust the RCM output toward observations. For gust speeds, an improvement on 88 of 100 events and at about 64% of the test sites is reached. For wind, 99 of 100 improved events and ~84% improved sites can be obtained. This gives confidence on the potential of the introduced approach for many applications, in particular those considering wind data.

Santa Ana winds and predictors of wildfire progression in southern California.

Santa Ana winds have been implicated as a major driver of large wildfires in southern California. While numerous anecdotal reports exist, there is little quantitative analysis in peer-reviewed literature on how this weather phenomenon influences fire progression rates. We analysed fire progression within 158 fire events in southern California as a function of meteorologically defined Santa Ana conditions between 2001 and 2009. Our results show quantitatively that burned area per day is 3.5-4.5 times larger on Santa Ana days than on non-Santa Ana days. Santa Ana definition parameters (relative humidity, wind speed) along with other predictor variables (air temperature, fuel temperature, 10-h fuel moisture, population density, slope, fuel loading, previous-day burn perimeter) were tested individually and in combination for correlation with subsets of daily burned area. Relative humidity had the most consistently strong correlation with burned area per day. Gust and peak wind speed had a strong positive correlation with burned area per day particularly within subsets of burned area representing only the first day of a fire, >500 ha burned areas, and on Santa Ana days. The suite of variables comprising the best-fit generalised linear model for predicting burned area (R 2 = 0.41) included relative humidity, peak wind speed, previous-day burn perimeter and two binary indicators for first and last day of a fire event.

日最大瞬間風速の超過確率に基づく風環境評価に用いる ガストファクターの提案

A criterion for pedestrian wind environment based on probability of exceedance of daily maximum gust wind speed is commonly used in Japan. We usually use gust factors to estimate the daily maximum gust wind speeds, using daily maximum mean wind speeds. But there still remains an unsettled problem of how to determine the appropriate gust factors. “A Working Group for Urban Wind Environment Assessment” in the Japan Association for Wind Engineering has been studying this problem to establish rational wind environment assessment method. The WG proposes a model equation of the gust factors based on field observation data at 152 sites, and confirms the applicability of it to the assessment of pedestrian wind environment

Modeling and investigation of Gulf El-Zayt wind farm for stability studying during extreme gust wind occurrence

This paper investigates the impact of extreme gust wind as a case of wind speed variation on a wind farm interconnected electrical grid. The impact of extreme gust wind speed variation on active and reactive power of the wind farms is studied for variable speed wind farm equipped with Doubly Fed Induction Generators (DFIGs). A simulation model of the under implementation 120MW wind farm at Gulf El-Zayt region, Red Sea, Egypt, is simulated as a case study. A detailed model of extreme gust wind speed variation is implemented and simulated, using MATLAB/Simulink toolbox, based on International Electrotechnical Commission IEC 61400-1 and climate characteristic of Gulf El-Zayt site. The simulation results show the influence of different extreme gust wind speed variations on the fluctuation of active power and reactive power at the Point of Common Coupling (PCC) of the studied wind farm.

Explosive development of winter storm Xynthia over the subtropical North Atlantic Ocean

Abstract. In winter of 2009–2010 south-western Europe was hit by several destructive windstorms. The most important was Xynthia (26–28 February 2010), which caused 64 reported casualties and was classified as the 2nd most expensive natural hazard event for 2010 in terms of economic losses. In this work we assess the synoptic evolution, dynamical characteristics and the main impacts of storm Xynthia, whose genesis, development and path were very uncommon. Wind speed gusts observed at more than 500 stations across Europe are evaluated as well as the wind gust field obtained with a regional climate model simulation for the entire North Atlantic and European area. Storm Xynthia was first identified on 25 February around 30° N, 50° W over the subtropical North Atlantic Ocean. Its genesis occurred on a region characterized by warm and moist air under the influence of a strong upper level wave embedded in the westerlies. Xynthia followed an unusual SW–NE path towards Iberia, France and central Europe. The role of moist air masses on the explosive development of Xynthia is analysed by considering the evaporative sources. A lagrangian model is used to identify the moisture sources, sinks and moisture transport associated with the cyclone during its development phase. The main supply of moisture is located over an elongated region of the subtropical North Atlantic Ocean with anomalously high SST, confirming that the explosive development of storm Xynthia had a significant contribution from the subtropics.

The Study of Wind Turbine Based on Fuzzy Logic

Due to the lack of fossil fuels, people are paying more and more attention to renewable energy. Wind energy is one of the important renewable energy. Unpredictability and volatility of the wind source make the output power unstable, so we need to control the active Power. This paper uses fuzzy control method, and the simulation results show that fuzzy control method mentioned in this paper is better than the conventional PI control for Wind power, the nonlinear system. Based on the analysis of pitch control theory and control process, we design fuzzy pitch controller and its model. We simulates gust wind speed imitates, wind turbine control and verifies the effects of the blur pitch control in a constant speed and constant frequency wind power generation system. According to the results of the simulation, we know the pitch controller of fuzzy logic has a better effect on the active control of the generator of the wind power generation system.

The Response of the Dines Anemometer to Gusts and Comparisons with Cup Anemometers

Abstract The Dines pressure tube anemometer was the primary wind speed recording instrument used in Australia until it was replaced by Synchrotac cup anemometers in the 1990s. Simultaneous observations of the gust wind speeds recorded using both types of anemometers during tropical cyclones have, however, raised questions about the equivalency of the gust wind speeds recorded using the two instruments. An experimental study of the response of both versions of the Dines anemometer used in Australia shows that the response of the anemometer is dominated by the motion of the float manometer used to record the wind speed. The amplitude response function shows the presence of two resonant peaks, with the amplitude and frequency of the peaks depending on the instrument version and the mean wind speed. Comparison of the gust wind speeds recorded using Dines and Synchrotac anemometers using random process and linear system theory shows that, on average, the low-speed Dines anemometer records values 2%–5% higher than those recorded using a Synchrotac anemometer under the same conditions, while the high-speed Dines anemometer records values 3%–7% higher, depending on the mean wind speed and turbulence intensity. These differences are exacerbated with the adoption of the WMO-recommended 3-s moving average gust wind speed when reporting the Synchrotac anemometer gust wind speeds, rising to 6%–12% and 11%–19% for low- and high-speed Dines anemometers, respectively. These results are consistent with both field observations and an independent extreme value analysis of simultaneously observed gust wind speeds at seven sites in northern Australia.