增加无功补偿

当电网中某一点增加无功补偿后,则从该点至电源点所串接的线路及变压器中的无功潮流将减少,从而使该点以前串接的元件中的电能损耗减少,达到了降损节能和改善电能质量的目的。增加无功补偿有三种可供选择,对于需要集中补偿的可按无功经济当量来选择补偿点和补偿容量;对于用户来说,可按提高功率因数的原则进行补偿,以减少无功功率受入;对于全电网来说,可根据增加无功补偿的总容量采用等网损微增率进行无功补偿。     

配电网无功补偿方式的研究

电压质量是衡量电力系统电能质量的重要指标之一,无功补偿是电网建设和改造的重要组成部分。本文指出了无功补偿对电网稳定运行的重要意义,介绍了无功补偿的原理、分类和无功补偿方式的选择方法。通过分析无功补偿对于电力系统的作用,并对配电系统四种无功补偿方案进行了技术比较,说明合理选择无功补偿的方式及容量,可提高功率因数,降低能量损耗,改善电压质量,从而达到节约电能和提高电能质量的目的。     

具有丰富谐波负荷的无功补偿和谐波抑制

建立了一个公共连接点短路参数(电感)与无功补偿电容的L-C并联谐振模型.谐振的驱动信号是用户晶闸管变流器产生250、350、550、650、850 Hz乃至更高频的谐波.谐振对电网、用户晶闸管变流器以及无功补偿装置都有危害.提出了在补偿电容上串联适当的限流电感把固有谐振频率控制在低于130 Hz的办法,这样电能质量能得到改善、用户能进行有效的无功补偿、无功补偿装置能保证可靠运行.     

无功补偿对电网的补偿效益

论述了电网无功补偿措施的优点.采用无功补偿可以提高电网效率,改善电能质量,降低电能损耗,发掘供电设备能力.     

配电网中的无功补偿方案及优化选择

无功补偿对电力系统的重要性越来越受到重视,合理地投停使用无功补偿设备,对调整电网电压、提高供电质量、抑制谐波干扰、保证电网安全运行都有着十分重要的作用。通过讨论无功补偿的意义、无功功率不足产生的不利影响、无功补偿的原则、如何确定无功补偿容量和方法、以及无功补偿电容器安装及运行中的安全问题等问题,希望做好无功优化,从客户的节能效益和提高电能质量为原则,积极探寻技术,以保证用电客户安全生产和经济运行。     

云南电网无功优化配置方案

在合理电网规划和电源规划的同时,进行无功规划是维持电网电压稳定和保证电能质量的不可缺少工作。根据"十二.五"云南电网规划,使用BPA软件对云南电网"十二.五"进行分层分区无功平衡分析。利用灵敏度分析找出无功补偿敏感点,从动态仿真角度研究了无功补偿类型。从优化角度论证了无功配置能够满足电网无功优化运行。提出的无功优化配置,对云南电网"十二.五"无功规划具有良好的指导意义。     

电能质量综合调节器UPQC研究

本文介绍了几种电能质量控制技术,利用电力电子技术来对电能进行控制是现在可行而且应用比较广泛的技术。重点介绍了统一电能质量调节器,它是一种彻底的改变电能质量问题的装置。它不仅能够补偿谐波和无功电流从而避免电网受到污染,而且还可以抑制各种各样的电能质量问题从而给用户提供高质量的电能。     

变电站母线无功功率平衡新方法探讨

变电站无功功率补偿,通常采用静止无功补偿装置,进行大容量集中补偿,主要是为了降低上级电网的无功损耗。根据变电站无功负荷性质的不同,采用不同的无功装置和补偿方案,可有效降低上级电网的电能损耗,提高电网的稳定运行。本文通过几种常用补偿方法的对比,提出采用“固定式＋新型自耦调压无功补偿”的混合型组合方法,对目前变电站建设及技术改造方案的选取较为适用。     

农村电网无功补偿与投切方式的探讨

介绍了农村电网无功补偿电源布点的实用方法及投切方式。无功容量的配置原则是：“全面规划，合理补偿，分级安装，就地平衡”。既要满足全规划区域总的无功电源平衡，又要满足分区、分线路的无功平衡，以便最大限度地减少电压和电能损耗。并应集中补偿与分散补偿相结合，以分散补偿为主。降损与调压相结合，以降损为主。供电部门补偿与用户补偿相结合。     

动态无功补偿装置在10kV配电系统中的应用

无功补偿是降低电网损耗,提高配电效率的有效手段,也是值得推广的一种节能措施。本文就动态无功补偿装置在10kV配电系统中的应用问题介绍了动态无功补偿装置的内涵和无功补偿的基本原理,对动态无功补偿装置的节能效益进行了分析,并提出了在10kV配电网中应用无功补偿存在的几个问题。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with