Multiobjective optimization in combinatorial wind farms system integration and resistive SFCL using analytical hierarchy process

This paper presents a positive approach for low voltage ride-through (LVRT) improvement of the permanent magnet synchronous generator (PMSG) based on a large wind power plant (WPP) of 50 MW. The proposed method utilizes the conventional current control strategy to provide a reactive power requirement and retain the active power production during and after the fault for the grid codes compliance. Besides that, a resistive superconducting fault current limiter (RSFCL) as an additional self-healing support is applied outside the WPP to further increase the rated active power of the installation, thereby enhance the dc-link voltage smoothness, as well as the LVRT capability of the 50 MW WPP. This is achieved by limiting the exceed fault current and diminishing the voltage dip level, leading to increase the voltage safety margin of the LVRT curve. Furthermore, the effect of the installed RSFCL on the extreme load reduction is effectively demonstrated. A large WPP has a complicated structure using several components, and the inclusion of RSFCL composes this layout more problematic for optimal performance of the system. Hence, the most-widely decision-making technique based on the analytic hierarchy process (AHP) is proposed for the optimal design of the combinatorial RSFCL and 50 MW WPP to compute the three-dimensional alignment in Pareto front at the end of the optimization run. The numerical simulations verify effectiveness of the proposed approach, using the Pareto optimality concept.     

城市中心“农业生态建筑”解读

解读以建筑农场为代表的农业生态建筑的形成背景、类型特点及生态技术,分析城市环境、居民与农业建筑、自然资源之间构成的生态循环特征,探讨我国未来都市农业发展方向。     

Turbulent times: tourists’ attitudes towards wind turbines in the Southern Highlands in Iceland

As a response to the threat of climate change, many nations are increasing their use of renewable energy, including wind energy. Large wind farms often conflict with other land uses, particularly tourism, which is a growing industry worldwide. In Iceland, tourism has recently become the largest export sector, with majority of tourists travelling to the country to experience its nature. This paper examines tourists’ opinions and perceptions of wind power development in the Southern Highlands of Iceland and compares how number, size and proximity of wind turbines, and the landscape in which they are situated, influence tourists’ perceptions. The study is based on an on-site questionnaire survey conducted in 2015. The results indicate that one-third of the travellers would be less likely to visit the Southern Highlands if a proposed wind farm were built, and two-thirds think that wind turbines would decrease the area’s attractiveness.     

Power quality impacts of high-penetration electric vehicle stations and renewable energy-based generators on power distribution systems

High-penetration renewable energy-based generators (REGs) in distribution systems have increased the importance of impact assessment involving these systems. This assessment focuses on power quality (PQ) and compatibility between REGs and existing system components. Electric vehicle (EV) technology has also recently achieved a substantial market share. This technology requires the development of charging stations similar to current petroleum fuelling stations in the near future. Thus, the effect of EV stations (EVSs) on PQ must also be considered. This study presents a PQ analysis on the effects of high-penetration EVS and REG systems, including wind turbines, grid-connected photovoltaics (PVs), and fuel cell (FC) power generation units on a modified 16-bus distribution system under different loading and weather conditions. All data on EVS, wind farm, PV, and FC units as well as weather conditions presented in this paper were collected from different power companies and the Malaysian Meteorological Department. The system is modelled and simulated using the MATLAB/Simulink software to study the effects of these technologies on system performances at various penetration levels. Simulation results indicated that the presence of high-penetration EVSs and REGs can cause severe PQ problems such as frequency and voltage fluctuations, voltage drop, harmonic distortion and power factor reduction.     

以单片机为核心的农用车性能综合测试仪

介绍了以MCS—51单片机为核心的农用车性能综合测试仪的主要性能、硬件结构和软件特点。     

北部引嫩渠首嫩江枯水期来水量与渠道引入量的分析

黑龙江省北部引嫩无坦引水工程，为大庆地区工业及沿途农业灌溉供水运行１６年来，由于引水口上拦沙坡和引水口上游江道河床的变化，枯水期嫩江来水量和供水量发生了矛盾。本文根据实测资料分析分流比减小的原因，并提出若干建议及措施。     

Metabolic and endocrine changes in response to endotoxin administration with or without oral arginine supplementation

This study was performed to investigate blood metabolite, tumor necrosis factor-alpha, and hormone responses to intravenous administration of lipopolysaccharides (2 microg of endotoxin of Escherichia coli 026:B6/kg body weight at times of feeding) in veal calves orally supplemented with arginine (0.25 g/kg of body weight twice daily for 4 d; group GrA) compared with calves not supplemented with arginine (group GrC). Arginine supplementation alone caused a significant rise of plasma arginine, urea, and insulin concentrations, whereas glucagon concentrations tended to increase, but there were no significant group differences. Concentrations of triglycerides, NEFA, glucose, protein, albumin, growth hormone, insulin-like growth factor-I, 3.5.3'-triiodothyronine, and thyroxine were not affected by arginine supplementation. Lipopolysaccharide administration alone caused a rise of tumor necrosis-factor-a, lactate, and cortisol concentrations and concentrations of tumor necrosis-factor-a after 1 h, and of triglycerides and urea after 6 h were higher, whereas of glucose after 3 h were lower in GrA than in GrC. Concentrations of NEFA, glucose, protein, albumin, insulin, growth hormone, insulin-like growth factor-I, 3.5.3'-triiodothyronine, and thyroxine were not affected by lipopolysaccharide administration. In conclusion, arginine supplementation had selective effects on plasma metabolites and hormones, but barely modified lipopolysaccharide effects. Effects of lipopolysaccharides in the postprandial state were different from what is usually seen in the fasted state.     

农用运输车发动机与传动系优化匹配的研究

针对目前农用运输车设计、生产中普遍存在的发动机-传动系匹配不够合理的现象,提出了以加速时间和变工况油耗为目标函数、多个约束的优化方法,用以确定当发动机给定后最佳的传动系速比,计算结果令人满意。     

高湿度高山风电场调研及设计特点分析

笔者通过对高湿度高山风力发电场、电力电缆生产厂家的走访、调研,结合规程规范对风电场接线设计、电缆集电线路选型、敷设工艺要求、运行维护注意点等事项进行了充分有效的沟通、交流并进行经验总结。     

航空摄影测量新方法在风电场大比例尺成图中的应用

针对传统航测成图方法的作业效率难以满足工程项目现实性需求的这一现状,文章通过对传统航空摄影测量成图的生产流程分析找寻改进空间,分别借助电子刺点作业模式、立体采集的规范化管理、基于AutoCAD Lisp的符号转码归层程序批量处理,对3个关键环节进行了技术改进,提高了成图效率。