轻型直流输电在风能并网上的应用

介绍了新一代轻型直流输电技术在风能并网方面的优势与应用。作为新能源风力发电目前在使用交流并网和常规直流输电并网时存在着一些技术上的问题,而轻型直流输电主要通过使用绝缘栅双极晶体管、电压源换流器技术和脉宽调制技术,使轻型直流输电在风能并网方面具有优越的独特作用,可以直接促进风电并网消除并网中的障碍得以快速发展。     

亚洲首条柔性直流输电线路试运行

5月3日,亚洲首个柔性直流输电示范工程——上海南汇风电场柔性直流输电工程成功投入试运行。这是我国第一条完全拥有自主知识产权,达到世界一流水平的柔性直流输电线路,也是我国在大功率电力电子领域取得的又一重大创新成果。该示范工程输送容量20MW,直流电压±30kV,是国家电网公司的重大科技示范项目,标志着公司成为继ABB、西门子之后全球第三家掌握该技术的企业。     

你应该了解的电力系统新技术 柔性直流技术

正柔性直流技术是20世纪90年代发展起来的一种新型直流输电技术,国际上也称为轻型直流输电(HVDC Light)、新型直流输电(HVDC Plus),国内将其命名为"柔性直流输电"。"柔性"一词来源于英文Flexible,表示应用先进的电力电子技术为电网提供灵活的控制手段。柔性直流技术以电压源换流器、自关断器件和脉宽调制(PWM)技术为基础,具有响应速度快、可控性     

资讯

<正>世界首个采用真双极接线柔性直流输电工程开建近日,中国电力建设集团所属福建院和中南电力设计院联合设计的厦门柔性直流输电科技示范工程彭厝换流站开始进场施工,标志着厦门柔性直流工程正式开工建设。该工程是世界上首个采用真双极接线的柔性直流输电工程,电压和容量均达到国际之最的柔性直流输电工程,工程额定电压±320 kV,额定容量1000 MW。柔性直流输电工程具有向无源电网(孤岛)供电、快速独立控制有功与无功、运行方式灵活等优点,项目的实施将切     

35 kV交流XLPE电缆两站线路改为三极式直流运行的参数设计

直流输电与交流输电相比具有供电容量大、线路损耗小、无须无功补偿且能充分发挥分布式能源的价值等诸多优点.同时,随着柔性直流输电技术的发展及环境保护的迫切要求,将交流线路改造成直流线路逐渐获得广泛关注 [1~3].     

一句话新闻

<正>2016年12月26日,国家发展和改革委员核准建设渝鄂直流背靠背联网工程。该工程采用柔性直流输电技术,有助于带动我国柔性直流输电领域的科技进步,推动电工装备产业升级,对于转变电网发展方式及全球能源互联网发展具有重要的创新和示范意义。1月3日,国家电网公司电网运检智能化分析管控系统上线仪式在北京举行。该系统是智能运检体系的重要     

VSC-HVDC输电系统的特点与应用

轻型直流输电系统是基于VSC技术的新型直流输电技术。介绍轻型直流输电基本原理,对比轻型直流输电技术与传统直流输电技术在结构和功能方面的区别,阐述轻型直流输电的优点,并对其应用进行总结和展望,以期为轻型直流输电技术在我国的应用和发展提供一定参考。     

35kV交流XLPE电缆两端线路改为三极式直流运行的参数设计

<正>直流输电与交流输电相比具有供电容量大、线路损耗小、无须无功补偿且能充分发挥分布式能源的价值等诸多优点。同时,随着柔性直流输电技术的发展及环境保护的迫切要求,将交流线路改造成直流线路逐渐获得广泛关注~[1~3]。对交流线路进行直流改造时,一种简单易行的方案是把一回线路改造成双极式直流线路。文献[4]介绍了一条     

柔性直流输电在城市配电网中的应用

通过结合相关研究资料,从简单说明柔性直流输电技术入手,重点围绕其在城市配电网中的实际应用与具体运用成效进行简要分析研究。     

风功率可控性分析

<正>1风电有功控制仿真建立包含风电场的电网模型,包括一次系统电路模型和有功控制模型。一次系统电路模型包括风电场模型、常规能源机组模型、变压器、输电线路和负荷模型。有功控制模型,包括机组控制模型、风电场控制模型和系统级AGC控制模型等内容,用于模拟风电场并网后有功功率波动、临时脱网运行、风电控制模式引入对电网调频影响和实时调度与AGC协调控制效果等内容仿真分析。包含风电场的电网模型如图1所示。     

Overland water and salt flows in a set of rice paddies

Cultivation of paddy rice in semiarid areas of the world faces problems related to water scarcity. This paper aims at characterizing water use in a set of paddies located in the central Ebro basin of Spain using experimentation and computer simulation. A commercial field with six interconnected paddies, with a total area of 5.31 ha, was instrumented to measure discharge and water quality at the inflow and at the runoff outlet. The soil was classified as a Typic Calcixerept, and was characterized by a mild salinity (2.5 dS m⁻¹) and an infiltration rate of 5.8 mm day⁻¹. The evolution of flow depth at all paddies was recorded. Data from the 2002 rice-growing season was elaborated using a mass balance approach to estimate the infiltration rate and the evolution of discharge between paddies. Seasonal crop evapotranspiration, estimated with the surface renewal method, was 731 mm (5.1 mm day⁻¹), very similar to that of other summer cereals grown in the area, like corn. The irrigation input was 1874 mm, deep percolation was 830 mm and surface runoff was 372 mm. Irrigation efficiency was estimated as 41%. The quality of surface runoff water was slightly degraded due to evapoconcentration and to the contact with the soil. During the period 2001–2003, the electrical conductivity of surface runoff water was 54% higher than that of irrigation water. However, the runoff water was suitable for irrigation. A mechanistic mass balance model of inter-paddy water flow permitted to conclude that improvements in irrigation efficiency cannot be easily obtained in the experimental conditions. Since deep percolation losses more than double surface runoff losses, a reduction in irrigation discharge would not have much room for efficiency improvement. Simulations also showed that rice irrigation performance was not negatively affected by the fluctuating inflow hydrograph. These hydrographs are typical of turnouts located at the tail end of tertiary irrigation ditches. In fact, these are the sites where rice has been historically cultivated in the study area, since local soils are often saline-sodic and can only grow paddy rice taking advantage of the low salinity of the irrigation water. The low infiltration rate characteristic of these saline-sodic soils (an experimental value of 3.2 mm day⁻¹ was obtained) combined with a reduced irrigation discharge resulted in a simulated irrigation efficiency of 60%. Paddy rice irrigation efficiency can attain reasonable values in the local saline-sodic soils, where the infiltration rate is clearly smaller than the average daily rice evapotranspiration.     

农村剩余劳动力就业问题的探讨

论述了我国农村剩余劳动力就业的意义，并针对我国农村剩余劳动力的现状，提出多渠道促进农村剩余劳动力就业的途径和办法。     

车用发动机润滑油失效规律与更换周期研究

研究在正常使用条件下１０Ｗ／３０－ＱＣ级润滑油用于某型车用发动机时所表现的失效规律,确认期服从两参数Ｗｅｉｂｕｌｌ分布,并给出分布的尺度参数η和形状参数ｍ之最佳线性无偏估计（ＢＬＵＥ）同时,还为定量分析,计算车用发动机润滑油的使用可靠性和合理确定其更换周期提供了一套可供借鉴的方法,并给出了具体的计算实例。     

瓦房店市水果生产标准化发展研究

瓦房店市是我国重要的水果生产基地,在国内水果生产领域占有重要地位。随着水果市场化的不断深入,如何满足和适应国内外市场需求成为瓦房店市水果生产的关键问题。从瓦房店市水果生产实际出发,阐述了实施水果生产标准化的必要性,提出了发展水果生产标准化的具体措施。     

金谷子耐旱TG118引种试种及推广应用

对引进的谷子新品种金谷子耐旱TG118进行品种比较试验和多点试种。结果表明：该品种抗旱、耐瘠、适应性强,稳产、高产、抗病抗风抗倒伏强,品质优良,粮草兼用,种植简单,省工易管;一般产量在6000kg/hm2以上,比当地主栽品种增产20%以上。最高产量达9450kg/hm2,适于在辽西北地区推广应用。     

对《种子法》存在问题的探讨

《种子法》是我国种植业第一部法律。自实施以来,为依法加强种子管理提供了有力的法律支撑,促进我国种子产业发生翻天覆地的变化。但随着依法管理工作的深入和种子产业的快速发展,《种子法》及配套规章的一些问题逐步显现出来。对《种子法》及配套规章存在的问题进行深入分析,对需要进一步补充的章节以及需要调整的内容进行深入探讨,以求更加完善和明确。     

乡（镇）农业技术推广体系存在的问题及对策

乡（镇）农技推广体系是农业发展的关键。介绍朝阳市农业技术推广体系的现状,针对目前体制及运行机制、服务手段等方面存在的问题,提出适合朝阳市乡（镇）农技推广体系改革与发展的对策,以期对全省农技推广体系改革和发展起到一些借鉴作用。     

草莓的采收与贮藏

草莓果味酸甜爽口,营养价值高,为人们所喜爱的应市鲜果之一。由于草莓易受损伤和微生物侵染,因此其采收、贮藏过程极为重要。介绍草莓采收过程中的注意事项以及11种贮藏保鲜技术的实施步骤和操作方法,推介9种加工方式,为草莓产业化提供技术支持。     

和谐社会理论建设的几点哲学思考

在新世纪,面对机遇和挑战,党的十六大把“社会更加和谐”作为全面建设更高水平的小康社会的一个重要目标。中国人素有社会和谐的理想;西方人自古也向往社会和谐;借鉴东西方两种和谐社会思想的经验、教训,构建社会主义和谐社会理论。     

Review of the Egyptian experience in implementing land drainage projects

About 30 years have passed since the Government of Egypt embarked on implementing a series of large scale drainage projects. At present, about 3.8 million acres have been provided with drainage systems on the basis of systematic pre-drainage investigations and designs. The target is to provide drains in approximately 6.4 million acres in the Nile Valley and Delta.The implementation of the subsurface drainage system is carried out by the public sector and private contractors under direct supervision of governmental regional departments. The implementation process depends on many factors related to the drainage material, machinery, manpower, site requirements, farmers and organizations involved. Problems and constraints are sometimes challenging, however, the annual rate of implementation has gradually increased to 170,000 acre/year.This paper discusses the different aspects involved in the implementation process of drainage systems. The development in materials, machinery and construction technologies will be reviewed. Institutional and management factors are going to be also considered.