Output power dispatch control for a wind farm in a small power system

Nowadays, a wind turbine generator (WTG) is required to provide control capabilities as the output power of WTG fluctuates. Under this scenario, this paper proposes an output power control method of a wind farm (WF) connected to a small power system using pitch angle control. In this control approach, the WF output power control is achieved by two control levels: central and local. In the central control, the WF output power command is determined by considering the frequency deviations and wind speeds using a fuzzy function. Then, the local output power commands for each of the WTGs are based on the proposed dispatch control. In the proposed dispatch control, the output commands of each WTG are determined by considering wind conditions for each of the WTGs. The simulation results by using an actual detailed model for the wind power system show the effectiveness of the proposed method. Copyright © 2010 John Wiley & Sons, Ltd.     

厌氧池/人工湿地/生物塘系统处理奶牛养殖场废水

采用厌氧池/人工湿地/生物塘的组合工艺对某奶牛养殖场废水进行处理.结果表明,该系统的处理效果良好,SS和COD主要在厌氧池和人工湿地中被去除,NH 4-N、TN和TP主要在人工湿地和生物塘中被去除,整个系统对SS、COD、NH 4-N、TN和TP的平均去除率分别为91%、74%、72%、62%和85%,出水水质可达到<农田灌溉水质标准>(GB 5084-2005)的要求.该系统的成本低廉且易于运行维护,具有良好的经济效益与环境效益.     

Exploring public preferences for traditional farming landscapes

Given that an increasing share of budgetary resources are now being spent on measures aimed at protecting the visual quality of agricultural landscapes it will be important to better understand individuals’ landscape preferences and the factors that influence those preferences. Within this context, using a nationally representive survey of Irish residents, the central aim of this study was to gain more insight into people's preferences regarding traditional farming landscapes. Individuals rated agricultural landscapes in terms of beauty quite highly but given a choice prefer traditional more extensive farming landscapes over more modern intensive farming landscapes. Moreover, the results suggest that there are systematic differences in preferences for traditional farm landscapes between different demographic groupings and also depending on individuals’ environmental value orientations. Accordingly, in studying preferences for agricultural landscapes in particular areas it will be necessary to consider the social and demographic characteristics of the population as well as the physical aspects of the landscape.     

罐区可燃气体探测器覆盖率评估及布置优化

液化烃属于甲A类火灾危险液体,一旦发生泄漏,遇点火源会产生严重后果.为了有效预防液化烃储罐气体泄漏,以某石化液化烃罐区为例,采用FLACS软件模拟液化烃泄漏及可燃蒸气气云溢散分布,通过分析蒸气云扩散规律对现有可燃气体探测器布置方案进行评估,并提出优化方案.结果表明,原有布置方案下可燃气体探测器覆盖率为46.88％,优化...     

从阜新市看资源枯竭型城市劳动力转移新规律

辽宁省阜新市是国务院确定的全国资源枯竭型城市经济转型唯一试点,阜新市经济转型和安置下岗失业矿工再就业最具有特色的做法是向现代农业和农产品深加工转移。本文肯定阜新市的做法是就业思路创新,是资源枯竭型城市劳动力转移一条新规律,提出在5种情况下可以运用这条规律以及要运用好这条规律必须注意解决的一些问题。     

海上风力发电现状与发展趋势

介绍了国外海上风电发展现状,提出了风电技术的发展降低了海上风电开发的成本,政府支持是海上风电发展的主要因素。从海上风能资源评估、风电机组及风电场设计等方面论述了海上风电技术的发展。研究结果表明,海上风电技术朝着低成本、大风电机组等方向发展,对我国海上风电发展具有参考价值。     

鄱阳湖区单退圩区水土资源利用的调研

通过对鄱阳湖区单退圩垸的水土资源利用、避洪农业开展的现状及存在的主要问题进行实地调研,提出了单退圩区农业产业结构调整的建议.     

季节性冻土对风电场杆塔基础稳定性影响研究

本文分析了风电场架空输电线路的特点以及季节性冻土对线路基础的危害,并结合风电场中35 kV直流输电线路杆塔基础的稳定进行分析.计算结果表明,在季节性冻土地区,特别是对冻深较大的地区,在基础埋深达到要求的同时,切向冻胀力也会对基础的稳定造成不利影响.因此,对季节性冻土地区的输电线路基础工程除按一般地区的要求进行设计施工外...     

配电系统潮流计算中风电场节点的处理方法

20世纪80年代以来,风力发电在世界范围内得到了迅猛发展.并网运行的风电场对配电系统的电能质量,潮流与网损等都将产生一定影响.潮流计算是对这些影响进行评估的最基本手段.介绍了含风力发电的配电系统的确定性潮流计算及随机潮流计算中风电场节点的不同处理方法,并进行比较,得出各自的适用场合.     

垂直坡度地形风电场的风资源特性研究

为了准确评估垂直坡度地形风电场的风资源特性,选取了风电场内两个具有代表性的位置进行现场测风,对测风数据进行综合对比分析表明,如果来流风向上存在垂直或近似垂直的坡度地形,会对坡顶边缘位置的风速和湍流产生不利影响,而随着向腹地的深入,不利影响将逐渐减弱.因此,机位选址时,在主风向上应尽量避免选择垂直坡度地形的坡顶边缘位置,...