Designed damping controller for SSSC to improve stability of a hybrid offshore wind farms considering time delay

This paper presents the stability improvement results of hybrid doubly fed induction generator (DFIG)-based and permanent magnet generator (PMG)-based offshore wind farms (OWFs) using a static synchronous series compensator (SSSC). An adaptive-network-based fuzzy inference system (ANFIS) controller of the proposed SSSC is designed to render adequate damping characteristics to the studied system. A frequency-domain approach based on a linearized system model using eigenvalue technique analysis is performed. A time-domain scheme based on a nonlinear system model subject to a three-phase short circuit fault at infinite bus with variations in the signal transmission delays has also been investigated to compare the damping of the studied system in cases of with and without controller. The simulation results with MATLAB/SIMULINK toolbox have been presented. It can be concluded from the simulation results that the proposed SSSC joined with the designed ANFIS damping controller can offer adequate damping performance to the studied hybrid DFIG-based and PMG-based OWFs under severe disturbance.     

光纤光栅感温火灾探测报警系统在原油罐区的应用

通过对现有罐区火灾自动报警技术的认真考察、对比,在石西集中处理站原油罐区安装了光纤光栅感温火灾探测报警系统.该报警系统的传感信号是光的波长变化,传感器及其探测系统是靠光缆连接而进入被测现场,它具有高安全性、高可靠性、高绝缘性、高抗电磁干扰性、防潮耐蚀、寿命长等其他传统火灾探测报警系统无法比拟的优越性能.阐述了其系统构成和运行效果.该系统在石西集中处理站运用效果良好.     

炼油厂成品油罐区调度优化问题研究

研究了以集合论为基础的调度优化模型。给出了该离散型优化问题的求解算法。根据优化结果，在G2实时智能平台上开发了包含监视子系统和调度子系统的调度支持系统。在中国石化股份有限公司长岭分公司的试用结果表明，该调度系统可以提高炼油厂的生产效率，从而提高炼油厂的经济效益。     

新库区储罐及地下钢结构阴极保护的应用及系统运行状况

新库区位于海滩上的回填土区 ,土壤pH值 5～ 6 ,地电阻≤ 2 5Ω·m ,土样含水量 12 %～ 2 4 % ,形成电导率高、透气性好和弱酸性的潮湿土壤 ,具有强的腐蚀性。此外 ,该区的土壤随着时间的推移 ,原海滩的盐碱通过扩散及毛细作用 ,使土壤的腐蚀性随含盐量增加而增强 ;因此 ,对新库区地下钢结构实施电化学阴极保护是很有必要的     

Analysis of lightning surge propagation in wind farm

Wind power generation is expected to become more important in future distribution systems. Although several prospective reports such as IEC 61400‐24 and NREL SR‐500‐31115 indicate an insulation scheme and grounding design for lighting protection, there still seems to be too few investigations on the problems. This paper therefore discusses lightning surge analysis using a wind farm model with 2 or 10 ideal wind turbines. Changing parameters such as grounding resistance and lightning strike points, several cases were studied. As a result of the analysis using digital simulator ARENE, it is clear that the surge tends to propagate toward the end of a distribution line in a wind farm and there is the possibility of insulation accidents at the other wind turbines when lightning attacks a wind turbine. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(2): 30– 38, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20364     

基于AHP的樱园农家乐SWOT分析及发展对策

利用AHP和SWOT分析理论,提出了西安樱园观光旅游农家乐的发展策略.根据实地调研,探讨了樱园农家乐发展所面临的优势、劣势、机遇和威胁,建立了总体层次分析评价指标体系,确定了各层次的指标权重,分析了四种备选的优化方案.最后建议,樱园农家乐的发展应充分发挥“体验参与模式”的优势,把握政府引导和政策支持的机遇.     

国有企业的技术创新问题与对策研究

指出技术创新是企业发展的必然趋势,因此,搞好技术创新对国有企业的发展至关重要。由于一些国有企业起步晚、基础薄弱、后劲不足,因而使其技术创新存在许多亟待解决的问题。针对这些问题,笔者通过认真思考,提出了自己的观点,从企业自身和外部环境2个方面,分析了国有企业技术创新的障碍,探究了其发展受制约的原因,并提出了一些行之有效的解决方法。     

Impacts of a marine fish farm in Argolikos Gulf (Greece) on the water column and the sediment

The aim of this study was the qualitative and quantitative assessment of impacts on the physicochemical characteristics of the water column and the sediment caused by an intensive marine fish farm. The study area was the Plateia Island which is located in an open seawater area in the outer part of Argolikos Gulf (Northeastern Peloponnese, Greece). The particular plant has been in operation since 1988, producing about 350-400 tons per year of Gilthead seabream (Sparus auratus) and European seabass (Dicentrarchus labrax). The samples were taken on a three-season period started in August 2001 and ended in May 2002. During this study, the main physical and geochemical parameters on the water column and the sediment were investigated. Specifically, the parameters that were measured included: ammonium-nitrogen, phosphate and suspended solids in the water column and organic matter, organic carbon, and phosphorus (total and inorganic) in the sediment samples. The conclusions drawn from this work clearly verify that the most important impacts, mainly identified as increased nutrients and organics concentrations both in the water column and the sediment, were realized at the stations closest to the farm. These concentrations gradually decreased with increasing distance from the cages. The peak values in most of the parameters measured were obtained during summer or spring. However, it has to be mentioned that although the measured concentrations clearly depict the influence of the fish farm especially on the sediment, their values were, in general, considerably lower than those reported in relative studies in Greek fish farms.     

鲁北平原养鸡场周边包气带与地下水砷化合物分布规律

洛克沙胂(3-硝基-4-羟基苯胂酸)被广泛用作饲料添加剂,但大部分以原体形式随粪便排出,进入环境的洛克沙胂在微生物和光照作用下最终转化为毒性较大的As(V)和As(III)等,并在雨水或农灌的淋滤冲积下污染周边土壤、地表水和地下水。以鲁北平原某养鸡场为研究区,对鸡粪、饲料、周边表层土壤、鸡粪堆积和背景包气带垂向剖面以及地下水进行洛克沙胂及其代谢物的检测,结果饲料中洛克沙胂浓度为34mg/kg,鸡粪中HAPA(3-氨基-4-羟基苯胂酸)浓度为11 mg/kg,距离鸡场越近的表层土壤砷含量越高。三个包气带垂向剖面均以As(V)为主,As(III)含量较小。鸡粪堆积处垂向剖面上HAPA、As(V)和As(III)在土壤表层含量最高,浓度随深度增加而呈下降趋势,同时受到土壤岩性的影响,砷化合物主要的吸附层位为0~30cm与200cm以下;背景包气带垂向剖面上各砷化合物含量均明显低于鸡粪堆积处包气带垂向剖面的砷化合物含量;在鸡场内旧井中检测到浓度为165μg/kg的As(V)。结果证实鸡粪堆积导致土壤包气带、周边土壤和地下水砷含量增加,且这种污染很难消除。     

基于AdaBoost.MH的Reyes渲染架构时间预估算法

在大规模真实感渲染系统中,需要对渲染任务进行分解和调度,将其优化后分配给不同的可用计算资源,实现快速集群渲染。为了实现渲染任务的有效分解和调度,提高并行效率,高精度的时间预估算法是不可欠缺的。通过深入研究使用RenderMan规范的渲染器常用的Reyes渲染架构中对渲染时间产生影响的各种因素,分析提取出影响渲染时间的7大要素特征,提出了基于AdaBoost.MH的渲染时间预估算法。通过在基于Reyes渲染架构的渲染引擎中的实验与测试表明,训练集和测试集的准确率分别达到79%和78%,为渲染任务的并行调度奠定了基础,同时也为渲染费用预估提供了依据。