Physics-based recalibration method of cup anemometers

Cup anemometer is the most widely used instrument in the natural environment. However, the accuracy of cup anemometer is not robust due to their inertial structures. In this study, the equation of motion (EOM) relating rotational motion of the cup rotor to aerodynamic force is investigated to reveal the cause of measurement error of cup anemometer. A new methodology is proposed to recalibrate cup anemometer based on theoretical analysis of the dynamic response of the cup rotor and random process theory. The unknown dynamic coefficients of the EOM are quantified by the numerical method using measurement results from inertial and non-inertial anemometers. A detailed example is presented to demonstrate the efficiency of this new method in which coefficients of the EOM are quantified from laboratory and field data. Both mean wind speed and the entire time history could be recalibrated using this new method. Comparing with the non-inertial anemometer results, the improvement rate of the recalibrated cup anemometer results is 29%–99%.     

Copula-based JPDF of wind speed,wind direction,wind angle,and temperature with SHM data

Structural health monitoring (SHM) systems installed on long-span bridges can obtain environmental data around them. To deeply mine the correlation between types of data, this paper proposes a multivariant joint probability density distribution function (JPDF) based on copula theory. Specifically, the univariate probability density function (PDF) is characterized by the finite mixture (FM) method, that is, the 1D model. In addition, the parameters in the FM distribution are estimated by the genetic algorithm (GA). Then, the bivariate JPDF based on copula theory is established, i.e., the 2D model; next, the trivariate JPDF is derived, i.e., the 3D model. Furthermore, the quaternary JPDF of wind speed, wind direction, wind angle, and temperature is derived, i.e., the 4D model. The feasibility of the proposed model is verified by a case study of a specific bridge in China, on which the SHM system is installed to collect SHM data including wind speed, wind direction, wind angle, and temperature. The trivariate JPDF of wind speed, wind direction, and wind angle, and the trivariate JPDF of wind speed, wind direction, and temperature based on FM are established.     

风沙流对戈壁风区桥梁防风栅响应规律的研究

为明确兰新二线桥梁防风栅的防风效果以及防风栅背风侧流场分布情况,选取兰新二线新疆段桥梁中最具代表性的32 m箱梁结构建模,基于Fluent风沙两相流非定常模型,运用标准κ-ε湍流模型,对风沙环境下高速铁路桥梁及防风栅整体风场分布特征进行定性的模拟分析.结果表明:在设置单侧、双侧防风栅后,会在防风栅背风侧形成一个相对连续...     

Optimal economic study of hybrid PV-wind-fuel cell system integrated to unreliable electric utility using hybrid search optimization technique

This study addresses the problem of power outages in distant districts by taking advantage of the available renewable energy resources in the surrounding environment. This was done by proposing connecting the utility to a hybrid system constituting from photovoltaic (PV), wind turbine (WT), and fuel cell (FC) systems where this hybrid system is considered as a backup system that works when the grid is unavailable. This hybrid system proposed is used for feeding the load to a tourist resort in Hurghada, Egypt.The design of the introduced system has taken into consideration the cost of purchasing electric energy and the profit from selling it to the utility network. Component scaling was implemented to improve the net present cost of the proposed system using two grouped meta-heuristic techniques, which are the Hybrid Firefly and Harmony Search optimization technique (HFA/HS) and compared to the particle swarm optimization (PSO) technique.Simulation results have shown that the optimal system for solving the grid unavailability consists of eighty PVs, two WTs, twenty FCs, forty-one electrolyzers, and one hundred eighteen hydrogen tanks. The results also showed that the volume of exchange with the grid has reached 4 GW of purchase and 3 GW of sale. It is manifest from the results that the suggested system is economically viable with an LCOE of 0.0628 $/kWh, which is less than the purchase of electricity from the grid for commercial users in Egypt, which is 0.1 $/kWh.     

Enhancing information for solar and wind energy technology deployment in Brazil

Brazil's primary energy matrix is based on more than 47% of renewables, and more than 85% of its electricity is generated by hydro power sources. Despite this large fraction of renewable energy resources, less than 0.3% of the national energy supply comes from solar or wind sources. This paper presents a diagnostic review on the penetration of the solar and wind energy technologies in Brazil. It also includes a survey of the latest government policies and incentives for renewable energies deployment by entrepreneurs, industry and commercial and residential consumers. In addition, the paper analyses how to best meet the requirements for policy support and information technology to boost the deployment of solar technology and wind energy in Brazil. This study was mostly based on results of a widely distributed survey covering key issues, and also by personal interviews carried out with key stakeholders in order to better understand the issues highlighted in the survey responses. The study pointed out some of the main obstacles to effectively promote and improve government policies and actions for investment in solar and wind energy market in Brazil.     

Policy analysis of authorisation procedures for wind energy deployment in Spain

The aim of this paper is to analyse the administrative procedures for the granting of authorisations for the siting of wind farms in Spain, currently the competency of regional authorities. The analysis reveals some commonalities and differences between the procedures across regions. Furthermore, some aspects regarding these procedures have raised the concern of different stakeholders, including the central government and wind energy investors. A conflict between the interests of the central and regional governments can be observed. Lack of coordination between the different administrative levels and the “more is better mentality” of regional authorities have led to a significant growth of wind energy requests for the (national) feed-in tariff. In turn, investors have complained about the discretionarity and non-transparency of those procedures and the lack of homogeneity across regions. This is likely to result in delays, uncertainty for investors and higher transaction costs. Although there has been a trend to a model which involves the use of multicriteria bidding procedures with more explicit, objective and precise criteria regarding project selection, the aforementioned problems suggest the need to improve coordination between the different administrative levels.     

Effect of temperature gradient on the erosion behavior of SiC coating for carbon/carbon composites in a combustion environment

SiC coating with a thickness of 50–70 µm was prepared on the surface of C/C composites by in-situ reaction method. The SiC coated C/C composites were then tested in a wind tunnel where a temperature gradient from 200 to 1600 °C could be obtained to investigate their erosion behavior. The results of wind tunnel test indicated that the service life of C/C composites was prolonged from 0.5 to 44 h after applying the SiC coating. After the wind tunnel test, three typical oxidation morphologies, including glassy SiO₂ layer, porous SiO₂ layer and clusters of honeycomb-like SiO₂ grains, were found on the SiC coated C/C composites. With the decrease of oxidation temperature, the amount of glassy SiO₂ declined and the thermal stress increased, which induced the cracking followed by the degradation of the SiC coating.     

国产1.5MW风力发电机组轮毂高度优化方案

以内蒙古西部某风电项目二期工程为例,提出打破以风电机组电机容量等级划分风机轮毂高度的旧有观念,面向发电能力最优的设计理念。通过将一期工程风电机组的轮毂高度由65m提升至70m,20年总收益提高1354万元,实现了风电场最佳投资收益。     

结构TMD风振控制最优参数设计方法

本文采用数值迭代法给出了风振控制中考虑主结构阻尼时ＴＭＤ最优参数实用设计表格。     

Parametric analysis of wind siting efficiency

The effect of wind climatic characteristics on the efficiency of the WECS is examined by means of the Weibull general model and a simple model of power curve. Two efficiency parameters—the plant utilization factor (F_u) and the site effectiveness (ε)—are considered as functions of three parameters: the Weibull shape parameter (k), a dimensionless mean wind speed (α), and the design ratio between rated and cut-in speed (φ). It is shown that only for intermediate values of α and φ the plant utilization factor can be considered independent of k, being otherwise either improved or penalized in no negligible measure by it, depending on the values of α and φ. The effect of increasing k on the site effectiveness is always beneficial. The effect of increasing α is beneficial for the plant utilization factor but largely penalizing for the effectiveness. However, no maximization is possible for neither of the efficiency parameters.It is shown that the correct use of F_u and ε for comparison is significant only for a given WECS, while the WECS data have to be used when comparing different or modified wind machines. The data of 35 commercial WECS are examined to show that the common assumption of constant rated or maximum efficiency is not acceptable.