Research on Representative Engineering Applications of Anemometer Towers Location in Complex TopographyWind Resource Assessment

The typical location and number of anemometer towers in the assessed area are the key to the accuracy of wind resource assessment in complex topography.As calculation examples,this paper used two typical complex topography wind farms in Guangxi,Yunnan province in China.Firstly,we simulated the wind resource status of the anemometer tower in the Meteodyn WT software.Secondly,we compared the simulated wind resource with the actual measured data by the anemometer tower in the same situation.Thirdly,we analyzed the influence of anemometer tower location and quantity in the accuracy of wind resource assessment through the comparison results.The results showed that the range which the anemometer tower can represent is limited(<5 kilometers),and the prediction error more than 5%.Besides,the anemometer towers in special terrain areas(such as wind acceleration areas)cannot be used as a representative choice.The relative error of the simulated average annual wind speed by choose different number of anemometer towers is about 4%,and the grid-connected power generation more than 6%.The representative effect of anemometer towers is of crucial for improving the accuracy of wind resource assessment in engineering applications.

Assessment Method of Offshore Wind Resource Based on Multi-dimenssiional Indexes System

Traditional assessment indexes could not fully describe offshore wind resources,for the meteorological properties of offshore are more complex than onshore.As a result,the uncertainty of offshore wind power projects would be increased and final economic benefits would be affected.Therefore,a study on offshore wind resource assessment is carried out,including three processes of“studying data sources,conducting multidimensional indexes system and proposing an offshore wind resource assessment method based on analytic hierarchy process(AHP).First,measured wind data and two kinds of reanalysis data are used to analyze the characteristics and reliability of data sources.Second,indexes such as effective wind speed occurrence,affluent level occurrence,coefficient of variation,neutral state occurrence have been proposed to depict availability,richness,and stability of offshore wind resources,respectively.Combined with existing parameters(wind power density,dominant wind direction occurrence,water depth,distance to coast),a multidimensional indexes system has been built and on this basis,an offshore wind energy potential assessment method has been proposed.Furthermore,the proposed method is verified by the annual energy production of five offshore wind turbines and practical operating data of four offshore wind farms in China.This study also compares the ranking results of the AHP model to two multi-criteria decision making(MCDM)models including weighted aggregated sum product assessment(WASPAS)and multi-attribute ideal real comparative analysis(MAIRCA).Results show the proposed method gains well in practical engineering applications,where the economic score values have been considered based on the offshore reasonable utilization hours of the whole life cycle in China.

Comparative Analysis for Evaluating Wind Energy Resources Using Intelligent Optimization Algorithms and Numerical Methods

Statistical distributions are used to model wind speed,and the twoparameters Weibull distribution has proven its effectiveness at characterizing wind speed.Accurate estimation of Weibull parameters,the scale(c)and shape(k),is crucial in describing the actual wind speed data and evaluating the wind energy potential.Therefore,this study compares the most common conventional numerical(CN)estimation methods and the recent intelligent optimization algorithms(IOA)to show how precise estimation of c and k affects the wind energy resource assessments.In addition,this study conducts technical and economic feasibility studies for five sites in the northern part of Saudi Arabia,namely Aljouf,Rafha,Tabuk,Turaif,and Yanbo.Results exhibit that IOAs have better performance in attaining optimal Weibull parameters and provided an adequate description of the observed wind speed data.Also,with six wind turbine technologies rating between 1 and 3MW,the technical and economic assessment results reveal that the CN methods tend to overestimate the energy output and underestimate the cost of energy($/kWh)compared to the assessments by IOAs.The energy cost analyses show that Turaif is the windiest site,with an electricity cost of$0.016906/kWh.The highest wind energy output is obtained with the wind turbine having a rated power of 2.5 MW at all considered sites with electricity costs not exceeding$0.02739/kWh.Finally,the outcomes of this study exhibit the potential of wind energy in Saudi Arabia,and its environmental goals can be acquired by harvesting wind energy.

Spatial-temporal Variation in Wind Resources at the Eastern Edge of Qaidem Basin, China

This paper analyzed time-series variation and spatial distribution characteristics of wind resources at the eastern edge of Qaidam Basin based on the wind resources gradient automatic observation system. Wind resources are relatively abundant in the study area, the cumulative number of hours of wind speed between 3–25m s -1 are more than 6600, equal to 275 days, exceeding 75% of total annual hours. Advantage wind velocity spectrum was in the scope of 3–9m s -1 at all gradients and the peak value of wind speed was 4–6m s -1 . Differences in the wind speed frequency distribution at other gradients were not apparent except for the 10m gradient. Compared with other layers, the occurrence frequency of small wind at the level of 10m was higher, while the occurrence frequency of wind speed between 6 and 12m s -1 was higher at other layers. The advantage wind direction in this area was northwest and the wind speed difference was not obvious. Wind speed and wind power density gradually increased with the increasing height, and differences among sites were apparent. The average wind turbulence intensity was 0.199 at each layer and the average shear index was 0.075; turbulence intensity and shear index gradually reduced from over a 10–70m gradient. Turbulence intensity had the same variation tendency as local temperature, whereby a high temperature corresponded to high turbulence and low temperature to low turbulence. The variation tendency of shear index was opposite to that for turbulence intensity; turbulence intensity gradually decreased from lower layers to top layers and shear index was most obvious between 10–30m. Turbulence intensity at each site at each level was between 0.10–0.25, and of medium intensity. These data will provide a technical gist for the layout of wind farms and the utilization of wind power resource at ground level throughout the study region.

Wind Energy Data Analysis and Resource Mapping of Dangla,Gojjam,Ethiopia

Energy is one of the most important factors in socio-economic development.The rapid increase in energy demand and air pollution has increased the number of ways to generate energy in the power sector.Currently,wind energy capacity in Ethiopia is estimated at 10,000 MW.Of these,however,only eight percent of its capacity has been used in recent years.One of the reasons for the low use of wind energy is the lack of accurate wind atlases in the country.Therefore,the purpose of this study is to develop an accurate wind atlas and review the wind resources using Wind Atlas Analysis and Application Program in Dangla so that the best sites used for the installation of wind farms can be easily identified.Wind climatology data,vector maps,and wind turbine data were used to model the Wind Atlas Analysis and Application Program.The wind data collected from National Meteorology Survey Agency over three years were used for the analysis.Besides,vector data for the survey area was prepared using Global Mapper V20.1.In this study,the Wind Atlas Analysis and Application Program tool was used to estimate wind resources.The wind resource map was developed at an altitude of 80 m above ground level,and a horizontal axis type wind generator called(i.e.,GridStreamer Vestas V1001.8 MW)was selected from the Wind Atlas Analysis and Application Program catalog to mimic the wind farm.The results obtained from the analysis of actual wind data showed that the minimum wind speed was 0.12083 m/s while the maximum wind speed was 9.96389 m/s.At a height of 10 m a.g.l.,the mean wind speed and wind power density were 1.8 m/s and 9 w/m2,respectively.The most common wind direction was also discovered to be 210 degrees.The maximum wind speed and capacity factor were available around hills,according to the wind resource map,and the net annual energy output of the Dangla wind farm at a turbine height of 80 m a.g.l.was found to be 282.726 GWh(or,32.27 MW).The farm’s capacity factor was also discovered to be 9.54 percent,indicating that the site is rated as low potential.

Spatiotemporal characteristics of wind energy resources from 1960 to 2016 over China

In the paper,daily near-surface wind speed data from 462 stations are used to study the spatiotemporal characteristics of the annual and seasonal mean wind speed(MWS)and effective wind energy density(EWED)from 1960 to 2016,through the methods of kriging interpolation,leastsquares,correlation coefficient testing,and empirical orthogonal function(EOF)analysis.The results show that the annual MWS is larger than 3 m s-1 and the EWED is larger than 75 W m-2 in northern China and parts of coastal areas.However,the MWS and EWED values in southern China are all smaller than in northern China.Over the past 50 years,the annual and seasonal MWS in China has shown a significant decreasing trend,with the largest rate of decline in spring for northern China and winter for coastal areas.The annual MWS in some areas of Guangdong has an increasing trend,but it shows little change in southwestern China,South China,and west of Central China.Where the MWS is high,the rate of decline is also high.The main spatial distributions of the annual MWS and the annual EWED show high consistency,with a decreasing trend year by year.The decreasing trend of wind speed and wind energy resources in China is mainly related to global warming and land use/cover change.

Discussion on the Assessment Method of Wind Energy Resources by Using Regional Meteorological Data

The exploitation status of wind energy resources was analyzed, and the distribution of wind energy resources and regional meteorological stations were introduced, and then the assessment method of wind energy resources by using data from regional meteorological station was studied taking Huangjin Regional Meteorological Station in Xinning County in Hunan Province for example, besides, corresponding software was compiled. By means of SQL database and program, the method was used simply and easily and had positive meaning for the development of wind energy resources and excavation of wind farm in inland region.

Evaluation Method for Offshore Wind Energy Resources Using Scatterometer and Weibull Parameters

The study discusses accuracy evaluation methods for offshore wind energy resources by using scatterometer SeaWinds-derived wind speed and Weibull parameters. The purpose of this study is to evaluate accuracies of SeaWinds-derived Weibull mean wind speed and energy density by considering uncertainties inherent in SeaWinds wind speed estimates. In this study, 1159 SeaWinds-derived wind speeds covering the KEO buoy are used for estimating two Weibull parameters, scale and shape. On the other hand, observed wind speeds from 2004 to 2008 at the KEO buoy are used for simulating three kinds of wind speeds in order to quantify some uncertainties inherent in SeaWinds-derived wind speeds. It is found that uncertainties associated with wind speed estimates （operational wind speed range, sampling time） show small differences in scale, shape and Weibull mean wind speed except energy density among the simulated datasets. Furthermore, the upper and lower bounds of 90% confidence interval corresponding to SeaWinds number of observations indicate 4-2.5% error of Weibull mean wind speed and 4-6.8% error of energy density, respectively.

HIGH-RESOLUTION NUMERICAL SIMULATION OF WIND ENERGY RESOURCE IN HAINAN PROVINCE AND ITS OFFSHORE WATERS

With high resolution （1 kin）, the distribution of wind energy resources in Hainan province and over its offshore waters is numerically simulated by using the Wind Energy Simulation Toolkit （WEST） model developed by Meteorological Research Branch of Environment Canada. Compared with observations from eight coastal anemometric towers and 18 existing stations in the province, the simulations show good reproduction of the real distribution of wind resources in Hainan and over its offshore waters, with the relative error of annual mean wind speed being no more than 9% at the 70-m level. Moreover, based on the simulated results of WEST grids that are closest to where the eight wind towers are located, the annual mean wind speeds are further estimated by using the Danish software Wasp （Wind Atlas Analysis and Application Program）. The estimated results are then compared with the observations from the towers. It shows that the relative error is also less than 9%. Therefore, WEST and WEST＋WAsP will be useful tools for the assessment of wind energy resources in high resolution and selection of wind farm sites in Hainan province and over its offshore waters.

Characteristics of Wind Speed Profiles under Complex Terrain Conditions in Loess Plateau

To reveal the changing characteristics of wind speed with altitude in under complex terrain conditions in Loess Plateau in Northern Shaanxi, based on the complete data of wind speed profiles of six wind towers in the region in a year, the diurnal, monthly, and seasonal variations of wind shear index of the wind towers as well as the changes of wind shear index with wind speed under complex terrain conditions were studied. The results showed that the wind shear index of each wind tower was positive, showing that wind speed tended to increase with the rising of altitude in most areas of Loess Plateau in Northern Shaanxi; terrain had obvious effects on wind speed profiles. The wind shear index of the wind towers was small during the day and large at night; the differences between day and night in the wind shear index of various wind towers were different; there were obvious seasonal variations in the wind shear index of the wind towers under different terrain conditions. With the increase of wind speed, the wind shear index of each wind tower increased firstly and then decreased, but the peaks of wind shear index of various wind towers ap- peared in different wind speed ranges. When wind speed varied from 3 to 12 m/s, wind shear index was larger than the comprehensive wind shear index of the wind towers, which is beneficial to the improvement of power generation of a wind power plant. Wind shear index can be used to assess wind resources of a wind power plant.

Seasonal Wind Characteristics and Prospects of Wind Energy Conversion Systems for Water Production in the Far North Region of Cameroon

This study aimed at investigating the characteristics of the wind power resource in the Far North Region of Cameroon (FNR), based on modelling of daily long-term satellite-derived data (2005-2020) and in-situ wind measurements data (1987-2020). Five different reliable statistical indicators assessed the accuracy level for the goodness-of-fit tests of satellite-derived data. The two-parameter Weibull distribution function using the energy factor method described the statistical distribution of wind speed and investigated the characteristics of the wind power resource. Six 10-kW pitch-controlled wind turbines (WT) evaluated the power output, energy and water produced. A 50 m pumping head was considered to estimate seasonal variations of volumetric flow rates and costs of water produced. The results revealed that the wind resource in FNR is suitable only for wind pumping applications. Based on the hydraulic requirements for wind pumps, mechanical wind pumping system can be the most cost-effective option of wind pumping technologies in FNR. However, based on the estimated capacity factors of selected WT, wind electric pumping system can be acceptable for only four out of twenty-one sites in FNR.

Wind Shear Investigation for Site-Specific Wind Turbine Performance Assessment

The wind energy assessment studies are generally performed referring to neutral stability conditions for the atmosphere; this is considered a good hypothesis because neutral conditions characterize the high wind situations. However the increasing size of modem multi megawatt wind turbines allows to produce energy even in low wind regimes and non-neutral conditions can involve significant production period. In such situations the variations of the vertical wind shear can affect the energy production in a sensible way and it could be fundamental to investigate how atmospheric stability and orography can affect the wind profile and the power conversion. In this paper meso-scale numerical data, CFD modeling and remote sensed wind data were used in order to analyze such behavior and to understand how wind shear influences the energy content and the discussion about how to adjust the power curve to the site specific conditions.

Wind Energy Generation Potential in Union Hidalgo, Mexico： A Preliminary Study

Union Hidalgo municipality in Oaxaca State, Mexico, is located in an area with attractive wind potential. For this reason, this paper presents a preliminary study of the technical feasibility of wind power generation in Union Hidalgo, by a micro-study with a higher resolution than that used in Wind Resource Atlas of Oaxaea, published in April 2004. In this work, the wind map of Union Hidalgo was generated using the micro-scale model WAsP 9.1, with a resolution of 50 meters. Wind speed and direction data recorded at 15 m and 32 m agl （above ground level） over four years and seven months in a surface anemometer station were used. With Class 7 wind patterns, the results show values that justify the installation of wind turbines to produce electricity in the area. Estimated capacity factors （55% on average） are comparable with those obtained in wind power plants already operating in areas near Union Hidalgo and sites with high wind potential in other parts of the world. The topography of the study area is predominantly flat, and together with the directional behavior of the wind, which comes from the NNW 44% of the time, this favors the introduction of wind power plants in the area.

Economic-Technical Feasibility Study of the ＂Sierra de Tineo＂ Wind Farm Expansion. Tineo-Principality of Asturias （Spain）

The aim of this work is double. Firstly, we want to stress out that investing in renewable energies in 2009 in Spain was a profitable activity. This question will be answered studying the possibilities of expanding ＂Sierra de Tineo＂ wind farm in the Principality of Asturias （location, wind resource, data analysis, simulation, legal standards and economic and sensitivity study of the investment）, and for that, data from the year 2009 have been used. And secondly, the goal is to set the bases for a future paper where the current situation of Spain （within the renewable framework）, will be compared with the 2009 scenario.

Analysis of Offshore Wind Power： Application to Southern Thailand

This paper presents an analysis of a pre-feasibility study of a 10 MW offshore wind power project in Nakhon Si Thammarat province, southern Thailand. The wind speeds at the hub heights of large scale wind turbine generators （WTG）, i.e. 80-100 m, were extrapolated using monthly mean wind shear coefficients and the l/7th exponent. Using WAsP 9.0, the annual energy production from several models of offshore wind farms using different WTG was analyzed. The capacity factor and the cost of energy were then computed. Using best available estimates, the analysis shows that the estimated annual mean offshore wind speeds at 80-100 m were in the range of 6.4 and 8.3 m/s. The annual energy production by the wind farm from nine models of wind turbine generators were in the range of 20-39 GWh/year, corresponding to a capacity factor in the range of 26-46%, while the cost of energy was 12-15 US cent/kWh.

Assessment of wind energy potential in China

China wind atlas was made by numerical simulation and the wind energy potential in China was calculated. The model system for wind energy resource assessment was set up based on Canadian Wind Energy Simulating Toolkit (WEST) and the simulating method was as follows. First, the weather classes were obtained depend on meteorological data of 30 years. Then, driven by the initial meteorological field produced by each weather class, the meso-scale model ran for the distribution of wind energy resources according each weather class condition one by one. Finally, averaging all the modeling output weighted by the occurrence frequency of each weather class, the annual mean distribution of wind energy resources was worked out. Compared the simulated wind energy potential with other results from several activities and studies for wind energy resource assessment, it is found that the simulated wind energy potential in mainland of China is 3 times that from the second and the third investigations for wind energy resources by CMA, and is similar to the wind energy potential obtained by NREL in Solar and Wind Energy Resource Assessment(SWERA) project. The simulated offshore wind energy potential of China seems smaller than the true value. According to the simulated results of CMA and considering lots of limited factors to wind energy development, the final conclusion can be obtained that the wind energy availability in China is 700～1 200 GW, in which 600～1 000 GW is in mainland and 100～200 GW is on offshore, and wind power will become the important part of energy composition in future.

Perspectives of China’s wind energy development

Wind energy is a kind of clean renewable energy, which is also relatively mature in technology, with largescale development conditions and prospect for the commercialization. The development of wind energy is a systematic project, involving policy, law, technology, economy, society, environment, education and other aspects. The relationship among all the aspects should be well treated and coordinated. This paper has discussed the following relationships which should be well coordinated: relationship between wind resources and wind energy development, relationship between the wind turbine generator system and the components, relationship between wind energy technology and wind energy industry, relationship between off-grid wind power and grid-connected wind power, relationship between wind farm and the power grid, relationship between onshore wind power and offshore wind power, relationship between wind energy and other energies, relationship between technology introduction and self-innovation, relationship among foreign-funded, joint ventured and domestic-funded enterprises and relationship between the government guidance and the market regulation, as well as giving out some suggestions.

Industrial Arrangement of Large-scale,Non-grid-connected Wind Power Industrial Zones in Coastal Areas of China

Constructing an industrial system for a large-scale,non-grid-connected wind power industry is a key step towards the diverse utilization of wind power.However,wind power exploitation is not only a technical challenge but an industrial problem as well.The objective of this study is to introduce a concept of large-scale,non-grid-connected wind power(LSNGCWP) industrial zones and establish an evaluation model to assess their industrial arrangement.The data of wind energy,industry,nature resources and socio-economy were collected in this study.Using spatial overlay analysis of geographic information system,this study proposes a spatial arrangement of the LSNGCWP indus-trial zones in the coastal areas of China,which could be summarized as the 'one line and three circles' structure,which will contribute to the optimization of the industrial structure,advance the wind power technology,coordinate the multi-industrial cooperation,and upgrade the industrial transformation of China's coastal areas.

Discussion on the Regional Division of the Development Stage of China's Wind Power

This paper constructs the index system of the regional division of the development stage of China's wind power resources,including the index of energy,the index of wind energy endowments and other indices.Based on principal component analysis and layered clustering analysis of these indices,and combined with the conceptual function of the development and utilization stage of the wind power,this paper divides the development and utilization stage of the wind power into four stages taking province as the basic yardstick:optimization growth stage,the rapid growth stage,the slow growth stage and the initial growth stage.In addition,this paper briefly discusses the basic strategy that should be adopted in each development stage of wind power resources.

Investigating the impacts of spatial-temporal variation features of air density on assessing wind power generation and its fluctuation in China

Air density plays an important role in assessing wind resource.Air density significantly fluctuates both spatially and temporally.But literature typically used standard air density or local annual average air density to assess wind resource.The present study investigates the estimation errors of the potential and fluctuation of wind resource caused by neglecting the spatial-temporal variation features of air density in China.The air density at 100 m height is accurately calculated by using air temperature,pressure,and humidity.The spatial-temporal variation features of air density are firstly analyzed.Then the wind power generation is modeled based on a 1.5 MW wind turbine model by using the actual air density,standard air densityρst,and local annual average air densityρsite,respectively.Usingρstoverestimates the annual wind energy production(AEP)in 93.6%of the study area.Humidity significantly affects AEP in central and southern China areas.In more than 75%of the study area,the winter to summer differences in AEP are underestimated,but the intra-day peak-valley differences and fluctuation rate of wind power are overestimated.Usingρsitesignificantly reduces the estimation error in AEP.But AEP is still overestimated(0-8.6%)in summer and underestimated(0-11.2%)in winter.Except for southwest China,it is hard to reduce the estimation errors of winter to summer differences in AEP by usingρsite.Usingρsitedistinctly reduces the estimation errors of intra-day peak-valley differences and fluctuation rate of wind power,but these estimation errors cannot be ignored as well.The impacts of air density on assessing wind resource are almost independent of the wind turbine types.