无功补偿外文翻译

1.无功补偿1.1.FACTS简介柔性交流输电系统（以下简称FACTS）是美国电力研究所（Electric Power Research Institule，EPRI）N.G.Hnigornai 博士于1986年首先提出。

它具有控制速度快、控制灵活、可靠性高、可连续调节、可迅速改变潮流分布等优点。

近年来成为电力系统稳定控制的一个重要研究方向。

目前，主要的FACTS 装置包括三大类。

第一类为并联装置，如静止无功补偿器（Static Var Compensator，SVC），它能够根据无功功率的需求自动补偿；静止无功发生器（Static Var Generator，SVG），它是最新出现的一种并联补偿装置，这是本文研究的主要对象。

第二类为串联装置，如静止同步串联补偿器（Static Synchronous Series Compensator，SSSC）、晶闸管控制串联电容器（Thyristor Controlled Series Capacitor，TCSC）等。

第三类为混合装置，如统一潮流控制器（United Power Flow Conrtollor ，UPFC）相间潮流控制器（Interphase Power Controller，IPC）等。

图1.1 无功补偿装置发展概况传统的静态无功补偿装置是无功补偿电容器，它具有结构简单、经济、方便等优点。

但是，它的阻抗是固定的，不能跟随负荷无功需求变化，也就是不能实现对无功功率的动态补偿。

且目前由于电力公司推行无功“返送正计”，即过补偿视为欠补偿，不可调的静态无功补偿会使功率因数大幅下降，所以要研究可调无功补偿技术。

1.2.可调无功补偿技术方案近几年，结合国外的先进技术，我国在无功补偿与谐波综合治理提出了许多可调无功补偿方案，无论哪种方案，都是力求基波下补偿牵引负荷感性无功功率，提高功率因数，并滤除（或抵消）指定谐波。

主要方案有：（1）真空断路器投切电容器。

reactive power auto-compensation controller1. GeneralThe controller is suitable for automatically adjusting of low voltage distribution sytem capacitor compensating device to make power factor get user’s predetermined state, increase service efficiency of power transformer reduce line loss,and inprove the voltage of power supply.2.Normal working and installation conditions2.1 Ambient temperature: -25℃~ +55℃2.2 Relative humidity: 40℃≤20%；20℃≤90%2.3 Altitude: ≤2500m2.4 Environmental conditions: no noxious gas and vapour; no conductivity or explosive dust; no violent mechnical vibration.3. Main structural features3.1 The capacity of the switched capacitor is calculated according to the reactive power and the compensation precision is high.3.2 High measuring precision of power factor and wide display range.3.3 Initial phase presetting (same polarity or current signal polarity is adjusted by software).3.4 Provided with two control modes such as power factor control mode and reactivepower controI mode.3.5 Friendly hUman-machine interface with convenient operation.3.6 Various fully digitalized control parameters，adjustable and visual with convenient use.3.7 Provided with two working modes such as automatic and manual running.3.8 Provided with protection functions for over-voltage and under-voltage.3.9 Provided with protection function for power failure to avoid data loss.3.10 Low current signal input impedance, ≤0.01Ω.4. Ordering notesUsers should supply the number of circuits, rated voltage, and type of switch (contactor or combination switch).无功补偿控制器1 概述无功功率自动补偿控制器，适用于低压配电系统电容器补偿装置的自动调节( 以下简称控制器)，使功率因数达到用户预定状态，提高电力变压器的利用效率，减少线损，改善供电的电压质量，从而提高了经济效益与社会效益。

电力专业常用英文单词翻译电力系统power system发电机generator励磁excitation励磁器excitor电压voltage电流current升压变压器step-up transformer母线bus变压器transformer空载损耗no-load loss铁损iron loss铜损copper loss空载电流no-load current有功损耗active loss无功损耗reactive loss输电系统power transmission system 高压侧high side输电线transmission line高压high voltage低压low voltage中压middle voltage功角稳定angle stability稳定stability电压稳定voltage stability暂态稳定transient stability电厂power plant能量输送power transfer交流AC直流DC电网power system落点drop point开关站switch station调节regulation高抗high voltage shunt reactor 并列的apposable裕度margin故障fault三相故障three phase fault分接头tap切机generator triping高顶值high limited value静态static (state)动态dynamic (state)机端电压控制AVR电抗reactance电阻resistance功角power angle有功（功率）active power电容器Capacitor电抗器Reactor断路器Breaker电动机motor功率因数power-factor定子stator阻抗impedance功角power-angle电压等级voltage grade有功负载: active load PLoad无功负载reactive load档位tap position电阻resistor电抗reactance电导conductance电纳susceptance上限upper limit下限lower limit正序阻抗positive sequence impedance 负序阻抗negative sequence impedance 零序阻抗zero sequence impedance无功（功率）reactive power功率因数power factor无功电流reactive current斜率slope额定rating变比ratio参考值reference value电压互感器PT分接头tap仿真分析simulation analysis下降率droop rate传递函数transfer function框图block diagram受端receive-side同步synchronization保护断路器circuit breaker摇摆swing阻尼damping无刷直流电机Brusless DC motor刀闸(隔离开关) Isolator机端generator terminal变电站transformer substation永磁同步电机Permanent-magnet Synchronism Motor异步电机Asynchronous Motor三绕组变压器three-column transformer ThrClnTrans双绕组变压器double-column transformer DblClmnTrans 固定串联电容补偿fixed series capacitor compensation 双回同杆并架double-circuit lines on the same tower单机无穷大系统one machine - infinity bus system励磁电流Magnetizing current补偿度degree of compensation电磁场:Electromagnetic fields失去同步loss of synchronization装机容量installed capacity无功补偿reactive power compensation故障切除时间fault clearing time极限切除时间critical clearing time强行励磁reinforced excitation并联电容器shunt capacitor<下降特性droop characteristics线路补偿器LDC(line drop compensation)电机学Electrical Machinery自动控制理论Automatic Control Theory电磁场Electromagnetic Field微机原理Principle of Microcomputer电工学Electrotechnics电路原理Principle of circuits电机学Electrical Machinery电力系统稳态分析Steady-State Analysis of Power System电力系统暂态分析Transient-State Analysis of Power System电力系统继电保护原理Principle of Electrical System's Relay Protection 电力系统元件保护原理Protection Principle of Power System 's Element 电力系统内部过电压Past Voltage within Power system模拟电子技术基础Basis of Analogue Electronic Technique数字电子技术Digital Electrical Technique电路原理实验Lab. of principle of circuits电气工程讲座Lectures on electrical power production电力电子基础Basic fundamentals of power electronics高电压工程High voltage engineering电子专题实践Topics on experimental project of electronics电气工程概论Introduction to electrical engineering电子电机集成系统Electronic machine system电力传动与控制Electrical Drive and Control电力系统继电保护Power System Relaying Protection主变压器main transformer升压变压器step-up transformer降压变压器step-down transformer工作变压器operating transformer备用变压器standby transformer公用变压器common transformer三相变压器three-phase transformer单相变压器single-phase transformer带负荷调压变压器on-load regulating transformer变压器铁芯transformer core变压器线圈transformer coil变压器绕组transformer winding变压器油箱transformer oil tank变压器外壳transformer casing变压器风扇transformer fan变压器油枕transformer oil conservator(∽drum变压器额定电压transformer reted voltage变压器额定电流transformer reted current变压器调压范围transformer voltage regulation rage 配电设备power distribution equipmentSF6断路器SF6 circuit breaker开关switch按钮button隔离开关isolator,disconnector真空开关vacuum switch刀闸开关knife-switch接地刀闸earthing knife-switch电气设备electrical equipment变流器current converter电流互感器current transformer电压互感器voltage transformer电源power source交流电源AC power source直流电源DC power source工作电源operating source备用电源Standby source强电strong current弱电weak current继电器relay信号继电器signal relay电流继电器current relay电压继电器voltage relay跳闸继电器tripping relay合闸继电器closing relay中间继电器intermediate relay时间继电器time relay零序电压继电器zero-sequence voltage relay差动继电器differential relay闭锁装置locking device遥控telecontrol遥信telesignalisation遥测telemetering遥调teleregulation断路器breaker, circuit breaker少油断路器mini-oil breaker,oil-mini-mum breaker 高频滤波器high-frequency filter组合滤波器combined filter常开触点normally opened contaact常闭触点normally closed contaact并联电容parallel capacitance保护接地protective earthing熔断器cutout,fusible cutout电缆cable跳闸脉冲tripping pulse合闸脉冲closing pulse一次电压primary voltage二次电压secondary voltage并联电容器parallel capacitor无功补偿器reactive power compensation device 消弧线圈arc-suppressing coil母线Bus,busbar三角接法delta connection星形接法Wye connection原理图schematic diagram一次系统图primary system diagram二次系统图secondary system diagram两相短路two-phase short circuit三相短路three-phase short circuit单相接地短路single-phase ground short circuit短路电流计算calculation of short circuit current自动重合闸automatic reclosing高频保护high-freqency protection距离保护distance protection横差保护transverse differential protection纵差保护longitudinal differential protection线路保护line protection过电压保护over-voltage protection母差保护bus differential protection瓦斯保护Buchholtz protection变压器保护transformer protection电动机保护motor protection远方控制remote control用电量power consumption载波carrier故障fault选择性selectivity速动性speed灵敏性sensitivity可靠性reliability电磁型继电器electromagnetic无时限电流速断保护instantaneously over-current protection跳闸线圈trip coil工作线圈operating coil制动线圈retraint coil主保护main protection后备保护back-up protection定时限过电流保护definite time over-current protection 三段式电流保护the current protection with three stages 反时限过电流保护inverse time over-current protection 方向性电流保护the directional current protection零序电流保护zero-sequence current protection阻抗impedance微机保护Microprocessor Protection。

附录1：外文翻译及资料A1.1实际中的谐波和无功补偿1．总述谐波在全世界的公共和工业网络中呈现一种增长的趋势。

这很明显的和工业和商业大厦中用到的非线性装载和设备有关。

这些非线性设备通常是可控硅整流器或二极管整流器，它们会造成电能质量的恶化，通常的以下的几种应用中会用到：-变速驱动(VSD)-为制造业和加工业-金属工业中的加热-大厦中的电梯、空调泵和风扇-工业和商业大厦中的不间断电源（UPS）-计算机和其他一些办公设备表1是典型DC驱动与6脉冲可控硅整流器整流器和表2是与6脉冲二极管整流器的典型的电压来源变换器驱动。

同样整流器在不同断电源(UPS)可以也被找到。

图3.用于开关方式电源的阶段整流器。

在表3是用于开关方式电源的带电容的阶段整流器。

这种电源是用途广泛在计算机，显示器和在许多其他电子设备。

整流器产生在谐波指令和频率下满足条件的谐波电流： 1±∙==p k f f n fn （1）这里：n f =谐波电流的频率f f =系统的基础频率n =谐波的指令k =1、2、3…p =整流器的脉冲数如果整流器被连接入大的总线，则谐波电流的振幅可以被计算如下： n l l n 1= （2）这里： n I =谐波电流的振幅‘n ’1I =整流器的基础电流n =谐波指令数 然而在真正的电网谐波电流比计算可能有比上面惯例(2)更高的振幅。

在下个章节有另外种类一些被测量的谐波电流整流器。

1.1在真正电网中的谐波电流表4是根本被测量的交流边，并且谐波电流直流驱动与它的装载信息。

能被看见第5谐波在这种情况下是28%对根本性的632A ，而它的根据惯例2的理论价值是20%。

图4 是带高负荷的直流驱动中的基波和谐波电流图 5 是低负荷直流驱动中的基波和谐波电流在表5有与表4一样，都是直流驱动，但是现有更低的负载，。

然而增加谐波的百分比之后基波电流从2261A被减少到1255A，例如第5谐波电流现在是基波电流的41%相当于515A.但是值得注意的是，谐波电流的绝对值是高在高装载情况之下。

电力系统 power system 发电机 generator 励磁 excitation励磁器 excitor 电压 voltage 电流 current升压变压器 step-up transformer 母线 bus 变压器 transformer空载损耗 no-load loss 铁损 iron loss 铜损 copper loss空载电流 no-load current 有功损耗 reactive loss 无功损耗 active loss输电系统 power transmission system 高压侧 high side 输电线 transmission line 高压 high voltage 低压 low voltage 中压 middle voltage功角稳定 angle stability 稳定 stability 电压稳定 voltage stability 暂态稳定 transient stability 电厂 power plant 能量输送 power transfer交流 AC 直流 DC 电网 power system落点 drop point 开关站 switch station 调节 regulation高抗 high voltage shunt reactor 并列的 apposable 裕度 margin故障 fault 三相故障 three phase fault 分接头 tap切机 generator triping 高顶值 high limited value 静态 static (state)动态 dynamic (state) 机端电压控制 AVR 电抗 reactance电阻 resistance 功角 power angle 有功（功率） active power 电容器 Capacitor 电抗器 Reactor 断路器 Breaker电动机 motor 功率因数 power-factor 定子 stator阻抗 impedance 功角 power-angle 电压等级 voltage grade有功负载: active load PLoad 无功负载 reactive load 档位 tap position电阻 resistor 电抗 reactance 电导 conductance电纳 susceptance 上限 upper limit 下限 lower limit正序阻抗 positive sequence impedance 负序阻抗 negative sequenceimpedance零序阻抗 zero sequenceimpedance无功（功率） reactive power 功率因数 power factor 无功电流 reactive current 斜率 slope 额定 rating 变比 ratio参考值 reference value 电压互感器 PT 分接头 tap仿真分析 simulation analysis 下降率 droop rate 传递函数 transfer function 框图 block diagram 受端 receive-side 同步 synchronization保护断路器 circuit breaker 摇摆 swing 阻尼 damping无刷直流电机 Brusless DC motor 刀闸(隔离开关) Isolator 机端 generator terminal变电站transformer substation永磁同步电机Permanent-magnet Synchronism Motor异步电机Asynchronous Motor三绕组变压器three-column transformer ThrClnTrans双绕组变压器double-column transformer DblClmnTrans固定串联电容补偿fixed series capacitor compensation双回同杆并架double-circuit lines on the same tower单机无穷大系统one machine - infinity bus system励磁电流 Magnetizing current 补偿度 degree of compensation电磁场:Electromagnetic fields 失去同步 loss of synchronization装机容量 installed capacity 无功补偿 reactive power compensation故障切除时间 fault clearing time 极限切除时间 critical clearing time强行励磁 reinforced excitation 并联电容器 shunt capacitor下降特性 droop characteristics 线路补偿器 LDC(line drop compensation)电机学 Electrical Machinery 自动控制理论 Automatic Control Theory电磁场 Electromagnetic Field 微机原理 Principle of Microcomputer电工学 Electrotechnics 电路原理 Principle of circuits电机学 Electrical Machinery电力系统稳态分析Steady-State Analysis of Power System电力系统暂态分析Transient-State Analysis of Power System电力系统继电保护原理Principle of Electrical System's Relay Protection电力系统元件保护原理Protection Principle of Power System 's Element 电力系统内部过电压Past Voltage within Power system模拟电子技术基础Basis of Analogue Electronic Technique数字电子技术Digital Electrical Technique电路原理实验Lab. of principle of circuits电气工程讲座Lectures on electrical power production电力电子基础Basic fundamentals of power electronics高电压工程High voltage engineering电子专题实践Topics on experimental project of electronics 电气工程概论Introduction to electrical engineering电子电机集成系统Electronic machine system电力传动与控制Electrical Drive and Control电力系统继电保护Power System Relaying Protection主变压器main transformer升压变压器step-up transformer降压变压器step-down transformer工作变压器operating transformer备用变压器standby transformer公用变压器common transformer三相变压器three-phase transformer单相变压器single-phase transformer 带负荷调压变压on-load regulating transformer器变压器铁芯transformer core变压器线圈transformer coil变压器绕组transformer winding变压器油箱transformer oil tank变压器外壳transformer casing变压器风扇transformer fan变压器油枕transformer oil conservator变压器额定电压transformer reted voltage变压器额定电流transformer reted current变压器调压范围transformer voltage regulation rage配电设备power distribution equipmentSF6断路器SF6 circuit breaker开关switch按button钮隔离开关isolator,disconnector真空开关vacuum switch刀闸开关knife-switch接地刀闸earthing knife-switch电气设备electrical equipment变流器current converter电流互感器current transformer电压互感器voltage transformer电源power source交流电源AC power source直流电源DC power source工作电源operating source备用电源Standby source强电strong current电weak current继电器relay信号继电器signal relay电流继电器current relay电压继电器voltage relay跳闸继电器tripping relay合闸继电器closing relay中间继电器intermediate relay时间继电器time relay零序电压继电器zero-sequence voltage relay差动继电器differential relay闭锁装置locking device遥控telecontrol遥信telesignalisation遥测telemetering调teleregulation断路器breaker,circuit breaker少油断路器mini-oil breaker,oil-mini-mum breaker高频滤波器high-frequency filter组合滤波器combined filter常开触点normally opened contaact常闭触点normally closed contaact并联电容parallel capacitance保护接地protective earthing熔断器cutout,fusible cutout电缆cable跳闸脉冲tripping pulse合闸脉冲closing pulse一次电压primary voltage二次电secondary voltage压并联电容器parallel capacitor无功补偿器reactive power compensation device消弧线圈arc-suppressing coil母线Bus,busbar三角接法delta connection星形接法Wye connection原理图schematic diagram一次系统图primary system diagram二次系统图secondary system diagram两相短路two-phase short circuit三相短路three-phase short circuit单相接地短路single-phase ground short circuit短路电流计算calculation of short circuit current自动重合automatic reclosing闸高频保护high-freqency protection距离保护distance protection横差保护transverse differential protection纵差保护longitudinal differential protection线路保护line protection过电压保护over-voltage protection母差保护bus differential protection瓦斯保护Buchholtz protection变压器保护transformer protection电动机保护motor protection远方控制remote control用电量power consumption载波carrier故障fault选择性selectivity速动性speed灵敏性sensitivity可靠性reliability电磁型继电器electromagnetic无时限电流速断保护instantaneously over-current protection 跳闸线圈trip coil工作线圈operating coil制动线圈retraint coil主保护main protection后备保护back-up protection定时限过电流保护definite time over-current protection 三段式电流保护the current protection with three stages 反时限过电流保护inverse time over-current protection方向性电流保护the directional current protection零序电流保护zero-sequence current protection阻抗impedance微机保护Microprocessor Protection。

河北科技师范学院外文翻译间歇性混乱运行开关功率变换器院(系、部名称:机电工程学院专业名称:电气工程及其自动化学生姓名:学生学号:指导教师:年月日河北科技师范学院教务处制间歇性混乱运行开关功率变换器在设计和施工过程中开关电源转换器,混乱的操作经常长时间间歇地观察正常运作。

在实践中,这种间歇性混沌操作就可消除融入设计相应的措施来打击假信号的干扰。

在本文中,我们解释导致间歇性混乱以一个受欢迎的形式的切换转换器,即电流型控制开关转换器建立电路模型用于研究现象具有耦合过程,通过伪信号耦合到当前遥感和斜坡补偿电路,导致边坡的调制补偿引起系统变得不稳定断断续续。

我们的分析表明,假信号耦合到斜坡补偿会导致间歇性混乱或次谐波操作。

关键词:开关电源转换器;电流型控制;间歇性混乱1 介绍间歇性混乱已被观察到开关电源。

尤其是当供给不适当保护,防止入侵的假讯号或寄生电感和电路存在,造成不必要的调制基本控制信号。

例如,在一个电流型控制功率转换器,电感电流采样和用于一个内环达到快速瞬态存在寄生电感、电容可能导致穗状或警告闯入的取样电感电流波形。

入侵也可以以不同的形式通过导电或辐射耦合路径。

有时,入侵者(假信号可以住在同一电路板或出席一个接近问题。

在本文中,我们展示了间歇性混乱运行在一个电流型控制开关转换器可适当进行建模和解释适应入侵的假讯号。

便于设计,我们确定临界参数,间歇性混乱操作和描述的方法来计算参数边界,间歇性混乱运行出现。

2概述的操作电流型控制提高转换器电流型控制的操作转换器可以这样描述如图1.指图1和略去了虚假的来源、提高转炉获得其周期切换方式,一个输入输出的作用,并定期重置时,电感电流等于参考水平。

通常,参考水平是衍生自1971年输出反馈在实践中。

此外,补偿斜坡信号强制合并消除固有的电流型变频器的控制。

在实践中,此外,补偿斜坡信号强制合并消除固有的电流型变频器的控制。

通常的排列图1显示的是和一些典型运行波形显示在图2。

文献翻译英文原文：Issues for reactive power and voltage control pricing in aderegulated environmentAbstractIssues related to reactive power, voltage support and transmission losses as dictated from a certain class of electric loads are addressed. Specifically, the impact of predominantly induction motor loads on voltage support, reactive power requirements, and transmission losses is examined. These issues are examined with a model, which explicitly models the induction motor mechanical load. Simulation results on a simplified electric power system are presented. Based on these results, a pricing structure for voltage and reactive power support is proposed. The basic assumption of the paper is that, in a deregulated environment, the expense of the incremental requirements for voltage control should be charged to the member causing the additional requirements. The results of this work can also be used to justify long-term pricing agreements between suppliers and customers.Keywords: Reactive power; Induction motor loads; Voltage support; Reactive power pricing1. IntroductionVoltage control in an electric power system is important for many reasons: _a.all end-use equipmentneed near-nominal voltage for their proper operation, _b. near-nominal voltageresults in near-minimum transmission losses, and _c. near-nominal voltages increase the ability of the system to with-stand disturbances _security.. A reasonable voltage profile throughout an electric power system is associated with the ability of the system to transferpower from one location to another. When the voltage sags to low values, this ability of the system is compromised. The onset of power transfer inability canbe detected with sensitivity analysis of reactive power requirements vs. real power load increases. This sensitivity is dependent on the characteristics of the electric load. Such sensitivity analyses have been performed using various electric load models, i.e. constant power load, constant impedance load, or combination of the two _voltage-dependent load. The majority of electric loadsare induction motors. These loads do not fit into any of the load model categories mentioned. Yet, they drastically affect the stability of the electric power system. In this paper, we assert the need to model induction motor loads within the power flow formulation and directly evaluate the effects of such loads on reactive power requirements. It is shown that the power flow formulation can be augmented to include the specific induction motor loads. Interesting nonlinear phenomena occur when the voltage at induction motor loads sags to low values. These phenomena affect the performance of the transmission system. In a deregulated environment, it makes sense to examine these phenomena and design a pricing model based on the economicimpact of these phenomena. The paper is organized as follows: first, a formulation is proposed, which explicitly models the induction motors. This formulation is introduced as an extension to the usual power flow problem.Then, a sensitivity analysis procedure is introduced. This sensitivity is basedon an extension of the co-state method. The proposed methods are applied toa simplified system comprising induction motor loads. The results of this system are discussed. A pricing approach for voltage support and reactive power requirements is presented.4. Example resultsThe application of the model presented in this paper is demonstrated on a simple electric power system, consisting of a generating substation, step-up transformer, a transmission line, step-down transformerand several induction motors. The system is illustrated in Fig. 2. Theparameters of the system have been selected to represent typical systems and they are shown in Table 1. It is important to realize that the motors may or maynot be controlled by variable voltage-variable frequency drives. For this system,we performed parametric studies of the voltage level, the reactive power requirement, and the transmission losses. The variable parameter is the total induction motor load. This parameter is denotedwith the variable y in Table 1. Also note that the model requires the mechanical load torque, T m . Theassumed mechanical torque is listed in Table 1.Fig. 3 illustrates the variation of the voltage magnitude and the generating unit reactive power outputas the total induction motor load increases. Note that, when the induction motor load increases beyond the value of 0.90 p.u., the reactive power requirement increase and the voltage magnitude decreases below 0.9 p.u. When the load increases beyond the value of 1.2 p.u., the voltage collapses.What happens in this case is that the induction motor moves to an operatingpoint of very high slip, in this case, ss0.27, absorbs higher reactive power and causes the termi-nal voltage to dip _voltage collapse.. Note that the voltage collapse is abrupt and unexpected. It is important to observe that this behaviorof the proposed Fig. 4. model is realistic and quite different from simplified models such as constant power or constant impedance load models.The performance of the system in the presence of induction motor loads canbe better understood by studying the sensitivity of voltage magnitude, reactive power requirements and transmission losses vs. induction motor load. Figs. 4–6 illustrate these sensitivities as functions of total induction motor rated load.In Fig. 4, it is apparent that the sensitivity of the voltage magnitude becomesvery high as the electric motor load approaches 1.2 p.u. It would be expedientto impose operating limits using the sensitivity of voltage magnitude. For example, if one is to apply limits to this sensitivity, i.e. 20%, then it is apparentthat for this system, the induction motor load should not be more than 0.8 p.u.of the system rated power. Similarly, one can observe in Figs. 5 and 6 that thesensitivity of reactive power requirements and transmission losses increase drastically as the induction motor load increases. It is important to note that when the induction motor load is 0.8 p.u., the sensitivity of reactive power torated load is 1.0, i.e. any additional 1 MW of load will require 1 MVA of generated reactive power. When the induction motor load becomes 1.0 p.u.,the sensitivity becomes 1.58 MVA /MW. Similarly, the transmission loss sensitivity with respect to load increases drastically as the induction motor load reaches 1.0 p.u. For example, when the load is 1.0 p.u., the incremental losses become 4%, a relatively high value.Figs. 4 –6 illustrate that at the point before the voltage collapse, the sensitivities become very high. Specifically, the voltage sensitivity is y1.0, the reactive power sensitivity is 3.8 MVA rMW and the transmission loss sensitivity is 0.094. This data can be used in two ways. First, application of limits onsystem sensitivities will ensure that the system never operates near the pointof voltage collapse. Second, the sensitivities can provide the basis for settingtariffs for voltage support and reactive power of predominantly induction motor loads. The basis of the tariff structure and its implementation is discussed in Section 5. One can argue that these tariffs may be applied to all loads for simplicity.The results in Figs. 3–6 were obtained for a specific system. The same information can be obtained for any system using the proposed model. Thenthis information can be utilized to impose tariffs for loads that arepredominantly induction motors.5. Tariff structureThe basis of the tariff structure is the cost of providing v oltage and reactive power support subject to acceptable system performance. Acceptable system performance can be established by imposing limits to the sensitivities of voltage magnitude and reactive power requirements. These limits are system dependent and should be decided upon extensive studies of the system. Thesame studies will providethe range of sensitivities of voltage magnitude, reactive power requirements and transmission losses. Adirect cost can be associated with the transmission losses. An investment costcan also be associatedwith reactive power requirements. Let x be the average transmission loss sensitivity and z be the maximum reactive power sensitivity. Then the cost of providing these services is:C=p1 x+p2 z ，where p1 is the price of electric energy, and p2 is the investment cost of reactive power sources.Note that the investment cost must be computed on the basis of the maximum requirements throughoutthe study period. The cost C provides the basis for establishing the actual tariffs. It is also important to note that, today, technology exists to monitor theimpact of a specific load on the system resources. Using this technology, onecan monitor the voltage magnitude, reactive power and most importantly the sensitivities of voltage magnitude, reactive power requirements, and transmission losses. It is conceivable that pricing can be performed in real timeon a use-of-resources basis.6. Summary and conclusionsThis paper has addressed the impact of predominantly induction motor loadson voltage magnitudes, reactive power requirements, and transmission losses.A model has been proposed to evaluate this impact on large-scale power systems. The proposed model incorporates the physical model of induction motors into the power flow formulation. As such, it is a realistic model and captures the true behavior of these loads.Example calculations were carried out on a simplified power system. For this system, the voltage level, the active and reactive power requirements, and the transmission losses were computed vs. the total induction motor load. The model provides sensitivities of these quantities with respect to the inductionmotor loads and can be used to predict the total amount of load, which can be supported by the system _voltage stability limit..It was shown that there is a critical value of the load and when the load increased beyond this value,the reactive power requirements and the transmission losses increase in a highly nonlinear fashion. Theonset of this condition is system dependent and can be determined with a series of simulations. A practical approach w ill be to use probabilistic simulation techniques, similar to those described in Ref., to obtain a statistical distribution of the critical induction motor loads.The results provide the basis for deriving aggregate electric load models andthe designing of a pricing schedule for voltage support and reactive power requirements. Specifically, the pricing is based on the cost function of the actual incremental losses and the cost of reactive power source requirements. Incremental loss cost is computed from the price of electric energy. The cost of reactive power sources is computed from the maximum required reactive power over a specified period of operation.译文：在解除管制的环境下功率和电压控制的定价问题摘要对由于处理某一类电负载而引起的功率、电压、传输损耗的相关问题的研究。

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中英文对照外文翻译(文档含英文原文和中文翻译)Optimization of reactive power compensation indistribution systemThe reactive power compensation for distribution network,as the supplement of substation compensation can effectively improve the power factor, reduce line loss, improve the end voltage, ensure the quality of power supply, also bring good economic benefits for enterprise, has received extensive attention. The distributed reactive compensation, installing power capacitors on feeders, is the main distribution network compensation mode at home and abroad [1], but different installed location and different installed capacity, the benefit is different. With the application of reactive power compensation distribution increase gradually, how to choose appropriate reactive compensation location and compensation capacity to make the maximum benefit with less cost become people's research target. And the optimization of distributed reactive compensation of distribution network was raised .At present, the decision of the best compensation capacity and the best position in actual distribution reactive compensation, usually in accordance with ideal situations, such as, the reactive load along the road distributed uniformly, increasing, diminishing distribution or as isosceles distribution, and so on [2], [9]. This method has clear results, simple calculation, and has a certain engineering practical value. But the actual reactive load distribution is more complex, which is different from the ideal situation. So, in accordance with ideal situations to premise reactive compensation configuration optimization formula may be not satisfied. To study a more general distributed reactive compensation configuration optimized method is needed.This paper studies several kinds of typical optimal allocation of reactive compensation configuration with ideal load distribution. Then it details the distributed reactive compensation optimized mathematical model,- 11 -which is applied to any load distribution or distribution network structure, and gives the effective algorithm. At last, the paper introduces the practical application of the research of the model and the algorithm.The ideal load distribution is refers to the reactive power load distributed along the line meet a kind of ideal regular distribution, for example, in any point the road reactive load is equal, named uniform distribution, the reactive load from the first end increasing or decreasing, named increasing or decreasing distribution, and so on. This is an abstract of the actual load distribution, and in such a hypothesis premise the analytical expressions of the optimal location and capacity can be deduced, which can get the best reduce loss effect. And the results are showed in Table I and Fig 1, which can be chose in practical projects [3], [4], [6].When the actual power distribution is different from the ideal situation, using the results to guide the reactive compensation configuration, the effect may be not beautiful. It needs to study a more general reactive compensation configuration optimized method.The optimization of distribution network distributed reactive compensation is distributed as a mixed integer nonlinear optimization problems, which is to determine the reactive compensation position and capacity with some constraints [5]. Therefore, the compensation position and capacity are the two decision variables. Its mathematical model is a two layers optimized problem with constraint. First is the capacity optimization at determined location, second is the distribution optimization. Based on the optimization mathematical model and algorithm, the corresponding graphical calculation software has been developed. With the optimization results, some power capacitors are installed on ten lOkV rural feederswhich had lower power factor and higher line loss. And the actual operation showed good effect. As shown in Fig 3 and Table II, it is the optimization of a feeder named CHANG 7.the total length is 22.35 km, the conductor type of trunk line is LGJ-120，with a distribution capacity of 4760 kVA. The active power- 12 -was 1904 kW, and the power factor was 0.83. The objective power factor was set at 0.9, so the reactive compensation total capacity was 358 kvar. The parameters including length and conductor type of each section, nameplate parameters of transformers, and the reactive compensation total capacity were set in the graphical software. Yet, the graph of the feeder had been drawn too. Then the results were marked on the feeder graph automatically, such as Fig. 3.As shown in Table II, theory line loss rate got an obvious 0.4149 percents decrement, if reactive compensation devices were installed. Also, under the condition of total capacity, two installations made 0.007 percent lower than one, and three points installation made 0.0003 percent lower than two. Then more compensation installations got more decrement of theory line loss rate, but the decreasing rate become inconspicuous, In contrast, equipment maintenance cost increased a lot. Therefore, two installations were selected onCHANG 7 feeder at last.This work provides scientific and reasonable theory for reactive power optimization of distribution network, and gives a reference for the distribution network loss calculation. Also, it provides the convenience for improving the quality of voltage, energy saving and improving line loss management level.1) For solving distribution network reactive power optimization problem, this paper puts forward the double optimization mathematical model of distribution network distributed reactive compensation, the inner is compensation capacity optimization, the outer layer is the reactive compensation distribution optimization. The model can do distribution reactive compensation optimization with any load distribution and arbitrary distribution network structure forms.2) By introducing Lagrange multiplier and the necessary condition of extreme, the mixed integer nonlinear optimization problem is deduced to a linear one that can be easily solved by Gaussian elimination method. It is- 13 -very imple and efficient for computer programming.3) The model and the algorithm can give different optimized results and loss reduction for different number of capacitor installation. Engineering practice showed that optimized capacitors installation can make line loss rate get an obvious decrement. This research plays an important role in the actual reactive compensation equipment installation of distribution network and line loss management.Reasonable reactive power sources compensation of rural substations h as been becoming a hot issue since Chinese rural electric network alteration. The principal reactive power compensation mode of rural substations is still using fixed compensation capacitor to control voltage and reactive power at present in China. This compensation mode has some problems. such as capacity adjustment requires manual intervention under power outage, the phenomenon of over and under compensation may always happen, the rate of putting into operation of reactive power compensation is relatively low, and so on . At the same time, there is no sampling function at the primary side of the main transformer because of the special devices in rural substations. In order to realize the objectives that the power factor is not less than 0.95 at primary side and not less than 0.9 at secondary side at the highest load, in this paper,some optimal reactive power control strategies for rural substation were proposed. In accordance with the reactive power flow conditions of the rural distribution network , the pros and cons of two control strategies were analyzed. One of the strategies was sampling at the primary side of the main transformer , the other was sampling at the s econdary side and switching control by power factor of secondary side. After comparison of such analysis, an optimal control strategy was p roposed. The data were sampledin the substation secondary side, then t he sampled data were evaluated in equivalence to the primaryside, and then the power factor assessment criteria of primary side were used t o control capacitor switching . The compensation capacity should be c- 14 -alculatedafter electric motor compensation , transformer compensation an d distributed compensation on distribution line.The sampled values at se condary side and active loss and reactive loss of themaintransformer w ere used to calculate compensation capacity to meet the power factor o bjectives of primary side. Through the example calculation and analysiby Applying actual substation data a result were obtained.The result met ap praisal standards and the power factor of main transformer primary sid e was above 0.95 at the highest load . If the power factor of main tran sformer secondary side was above 0.98 , there was no need to co mpensate for substation . If the power factor of main transformer secondaryside was under 0.97,after the compensation by using the p roposed optimal compensation capacity and the primary side power f actor control method, the power facto r of the main transformer se condary side was not less than0.98 and the primary side reaches 0.95. T hese results show that the proposed optimal control strategy and compe nsation capacity calculation method are feasible, and the research haspra ctical significance of making full use of reactive power supply in rural di stribution network.Optimal allocation of reactive power compensation plays an important role in power system planning and design. However, as a non-linear, larg e scale combinatorial . optimization problem, Conventional methods are not normally appropriate for it.A mathematical model is firstly presented in this paper for comprehensive optimal configuration in distribution feeders based on the analysis of engineering factors of reactive power compensation, whose objective is to minimize the annual expenditure involving the devices investment and the income of energy saving, and satisfy all sorts of operation ，fixing and maintenance constrains . The control variable include the capacitor banks’number and capacity of various compensation schemes. RARW-GA algorithm is adopted to solve this problem.The result of calculation and analysis of BenXi Steel group c orporation power system shows that the proposed method is feasible- 15 -and effective.An improved TS algorithm is put forward on the condition that reactive power compensation location and capacity have been identified in rural distribution lines. The Algorithm is based on capacitor optimal on-off model aimed at a minimum network loss, it can control the capacitor on-off according to the load changing and the system operation status and keep real-time voltage qualified and network loss minimum. A distributed control system is designed by using the algorithm to realize reactive power optimization, which is composed of reactive power optimal terminals and background control center. The terminal is in charge of data collection and transmission, on-off instruction receiving and executing. The control center in in charge of receiving data from every compensation point, calling control algorithm to process data, forming and sending instructions. GPRS technology is adopted to realize the system’s foreground-background communication. The actual application in some experimental networks has proved that the system can realize global optimal control for distribution lines, and is suitable to be widely used in rural distribution network.In order to solve the optimization of distribution reactive compensation point and capacity, a double optimized model is proposed, which is sui able for reactive compensation optimizationwith random load distribution or random network structure. For the compensation position and capacity decision variables, the optimized model is described as two layers of optimization with constraint . The outer one is the capacity optimization at determined location , and the inlayer is the location optimization . By introducing Lagrange multiplier, the mixed integer nonlinear optimization is deduced to a linearone that can be easily solve by Gaussian elimination method. For illustration, an application of ten 10kV rural feeders is utilized to show the feasibility of the double optimized model in solving the optimization of distribution reactive compensation point and capacity. Empirical results show that the model can give the optimized result for different number of capacitor installa-- 16 -tion, and the result with highest line loss decrementwill be used as thefi nal decision.The research provides scientific theoretical basis for Reactive compensation and plays a vital role in reactive compensation equipment installation and line loss management.Taking account of the mutual impacts of distributed generation and reactive power , to determine the optimal position and capacity of the compensation device to be installed , the paper proposed an improved Tabu search algorithm for reactive power optimiza-tion . The voltage q uality is considered of the model using minimum network active power l oss as objective Function . It is achieved by maintaining the whole s ystem power lossa minimum thereby reducing cost allocation. On the ba sis of general Tabu search algorithm , the algorithm used memory gu idance search strategy to focus on searching for a local optimum va lue, avoid a global search blindness . To deal with the neighborhood so lution set properly or save algorithm storage space,some corresponding i mprovments are made, thus, it is easily to stop the iteration of partial optimization and it is more probable to achieve the global optimizationb y use of the improved algorithm.Simulations are carried out on standard IEEE 33 test system and results are presented.SupSuperconducting Magnetic Energy Storage SMES) can inject or absorb real and reactive power to or from a power system at a very fast rate on a repetitive basis. These characteristics make the application of SMES ideal for transmission grid control and stability enhancement. Superconducting Magnetic Energy Storage SMES) is an attractive apparatus for some power system applications because it is capable of leveling load demand with high efficiency, compensating for load changes, maintaining a bus voltage, and stabilizing power swings. Power system stability problems have attracted the attention of power system engineers for several decades. Considerable progress has been made on excitation control, governor control, control by static var compensator, etc. Modern power systems, which are growing in size and complexity, are characterized by long distance bulk power transmissions and- 17 -wide area interconnections.In such power systems, undamped power swings of low frequency can occur. This can be a serious problem since the instability often decreases the power transmission capacity. As a result, the power that can be transmitted in steady state and transient situations is limited. If the limit is exceeded, the generator loses synchronous operation and system instabilities occur. SMES may be an effective means of preventing these instabilities, thereby maximizing power transfer to meet increased load demand. A SMES system can be represented in dynamic simulations as a continuous controllable real and reactive power source. In steady-state simulations, SMES can be represented as a continuous controllable reactive power source since it can continuously operate throughout its range of reactive power. However, the output of real power from a SMES device is limited to the amount of energy stored in the coil. The first objective of this research is to determine the optimal internal control scheme needed to decide the controllable active and reactive power based on active and reactive power demanded by the power system. The second objective is to design and simulate SMES external control models which are dependent on the network configuration. The third objective is to determine how the optimal size of a SMES device varies for a given transient stability disturbance when alternative internal control models and external control models are used.With a big number of electric energy consumers and different characters electric energy quality depends on many factors in the modern power networks. It includes: power networks and working condition factors of consumers. One of them is the possibility of reactive power balances with an important reserve providing after emergency modes on the basic knots of the power system and voltage regulation on all networks.As the length of networks of a power system increases in modern conditions, we can reduce the reactive power streams, as well as operational and capital expenses. Rational voltage mode brings to the front plan the- 18 -technical一economic aspects of the power transmission EFFICIENCY. Analyses and economic calculations show that transferring the reactive power by short length lines means of a high voltage justifies. Therefore in most cases reduction of reactive power to the minimum is very effective for economically when the sources of reactive power settle down near the consumption centers.The increase of consumer loading and its structure qualitative causes considerable increase of reactive power and constant reduction of a power factor in distributed power networks [ 1」.Thus, the tendency of modern power systems development is characterized by one side with the increase of reactive power consumption (in some systems to 1 kVAR/kVt), on the other side with decrease of power plant generators usage expediency and possibility for the reactive power compensation purpose [2-5]. In such conditions reactive power compensation attains a specialurgency. Here the optimization's primary goal is optimum placing of reactive power sources andsupport of a necessary reserve of capacity QreZ for voltage regulation on loading knot. For example, Polish power engineers consider that capacity of compensators should be 50% of the established capacity of generators in power plants. In France, Sweden and Germany the capacity of compensators is 35% of active peak loading, in the USA and Japan this volume is 70%. In different power systems of the USA the established capacity of compensators is 100% of generators capacities [6-11].Reactive power compensation problem is a multidimensional problem on the technical andeconomic aspects and consequently it is resulted with the finding of a global extremum of criterion function with the set of local extreme. In this article the voltage support within the technical restrictions and definition of optimal placing of the reactive power sources with a technique of multi-purpose- 19 -optimization of reactive power in the power system is considered. By the problem consideration as one-target optimization within restrictions the criterion function is a linear combination from several factors. The problem decision is a unique optimum version and has lacks of alternative versions, and there is not dependency of an end result from the initial data.Thus, the purpose of reactive power sources optimal placing in a power system consists ofincrease the quality of voltage in all central points of a network, control the stability of the system, reduce the power losses and capacities in networks. As a result these will increase the economic efficiency in the power system. From the economic efficiency point of view the new compensating units intended for installation should be proved and given corresponding optimum recommendations.1 .Methods and multi-purpose optimization compensations algorithms have been developed with support of a necessary reserve for preservation of normal level of voltage taking into account technical restrictions in knots of an electric network of a power system. Results of computerization to realization have shown speed and high efficiency the developed algorithm providing minimization of losses of active capacity in a net.2. Based on genetic algorithm the power and installation locations of the static capacitor banks with the multicriteria optimization technique has given. In this case, as a criterion of optimality the minimum expenses for the installation and exploitation, the minimization of power losses during the required values of voltage and power factor and maximum saving and the minimum self-payment term are accepted.3. The report of the real electricity network is given for two cases: operation without the CB;with optimal placement of CB. The application of the proposed method can reduce the averagepower losses approximately 13一14% in the electric network.- 20 -配电系统无功补偿装置容量优化配电网无功补偿，作为补充的变电站补偿可以有效地提高功率因数，减少线路损耗，提高末端电压，保证供电质量，也能带来良好的企业的经济效益，已得到泛的注意。

变压器专业英语翻译1、元件设备三绕组变压器：three-column transformer ThrClnTrans双绕组变压器：double-column transformer DblClmnTrans 电容器：Capacitor并联电容器：shunt capacitor电抗器：Reactor母线：Busbar输电线：TransmissionLine发电厂：power plant断路器：Breaker刀闸(隔离开关)：Isolator分接头：tap电动机：motor-------------------------------------------------------------------------------- 2、状态参数有功：active power无功：reactive power电流：current容量：capacity电压：voltage档位：tap position无功损耗：reactive loss有功损耗：active loss功率因数：power-factor功率：power功角：power-angle电压等级：voltage grade空载损耗：no-load loss铁损：iron loss铜损：copper loss空载电流：no-load current阻抗：impedance正序阻抗：positive sequence impedance 负序阻抗：negative sequence impedance 零序阻抗：zero sequence impedance电阻：resistor电抗：reactance电导：conductance电纳：susceptance无功负载：reactive load 或者QLoad有功负载: active load Load遥测：YC(telemetering)遥信：YX励磁电流(转子电流)：magnetizing current 定子：stator功角：power-angle上限:upper limit下限：lower limit并列的：apposable高压: high voltage低压：low voltage中压：middle voltage电力系统power system发电机generator励磁excitation励磁器excitor电压voltage电流current母线bus变压器transformer升压变压器step-up transformer高压侧high side输电系统power transmission system输电线transmission line固定串联电容补偿fixed series capacitor compensation 稳定stability电压稳定voltage stability功角稳定angle stability暂态稳定transient stability电厂power plant能量输送power transfer交流AC装机容量installed capacity电网power system落点drop point开关站switch station双回同杆并架double-circuit lines on the same tower 变电站transformer substation补偿度degree of compensation高抗high voltage shunt reactor无功补偿reactive power compensation故障fault调节regulation裕度magin三相故障three phase fault故障切除时间fault clearing time极限切除时间critical clearing time切机generator triping高顶值high limited value强行励磁reinforced excitation线路补偿器LDC(line drop compensation)机端generator terminal静态static (state)动态dynamic (state)单机无穷大系统one machine - infinity bus system 机端电压控制AVR电抗reactance电阻resistance功角power angle有功（功率）active power无功（功率）reactive power功率因数power factor无功电流reactive current下降特性droop characteristics斜率slope额定rating变比ratio参考值reference value电压互感器T分接头tap下降率droop rate仿真分析simulation analysis传递函数transfer function框图block diagram受端receive-side裕度margin同步synchronization失去同步loss of synchronization 阻尼damping摇摆swing保护断路器circuit breaker电阻：resistance电抗：reactance阻抗：impedance电导：conductance电纳：susceptance导纳：admittance电感：inductance电容: capacitance-------------------------------------------------------------------------------- Absorber Circuit ——吸收电路AC/AC Frequency Converter ——交交变频电路AC power control ——交流电力控制AC ower Controller ——交流调功电路AC Power Electronic Switch ——交流电力电子开关Ac Voltage Controller ——交流调压电路Asynchronous Modulation ——异步调制Baker Clamping Circuit ——贝克箝位电路Bi-directional Triode Thyristor ——双向晶闸管Bipolar Junction Transistor-- BJT ——双极结型晶体管Boost-Buck Chopper ——升降压斩波电路Boost Chopper ——升压斩波电路Boost Converter ——升压变换器Bridge Reversible Chopper ——桥式可逆斩波电路Buck Chopper ——降压斩波电路Buck Converter ——降压变换器Commutation ——换流Conduction Angle ——导通角Constant Voltage Constant Frequency --CVCF ——恒压恒频Continuous Conduction--CCM ——（电流）连续模式Control Circuit ——控制电路Cuk Circuit ——CUK斩波电路Current Reversible Chopper ——电流可逆斩波电路Current Source Type Inverter--CSTI ——电流（源）型逆变电路Cycloconvertor ——周波变流器DC-AC-DC Converter ——直交直电路DC Chopping ——直流斩波DC Chopping Circuit ——直流斩波电路DC-DC Converter ——直流－直流变换器Device Commutation ——器件换流Direct Current Control ——直接电流控制Discontinuous Conduction mode ——（电流）断续模式displacement factor ——位移因数distortion power ——畸变功率double end converter ——双端电路driving circuit ——驱动电路electrical isolation ——电气隔离fast acting fuse ——快速熔断器fast recovery diode ——快恢复二极管fast recovery epitaxial diodes ——快恢复外延二极管fast switching thyristor ——快速晶闸管field controlled thyristor ——场控晶闸管flyback converter ——反激电流forced commutation ——强迫换流forward converter ——正激电路frequency converter ——变频器full bridge converter ——全桥电路full bridge rectifier ——全桥整流电路full wave rectifier ——全波整流电路fundamental factor ——基波因数gate turn-off thyristor——GTO ——可关断晶闸管general purpose diode ——普通二极管giant transistor——GTR ——电力晶体管half bridge converter ——半桥电路hard switching ——硬开关high voltage IC ——高压集成电路hysteresis comparison ——带环比较方式indirect current control ——间接电流控制indirect DC-DC converter ——间接DC- DC转换器insulated-gate bipolar transistor---IGBT ——绝缘栅双极晶体管intelligent power module---IPM ——智能功率模块integrated gate-commutated thyristor---IGCT ——集成门极换流晶闸管inversion ——逆变latching effect ——擎住效应leakage inductance ——漏感light triggered thyristo---LTT ——光控晶闸管line commutation ——电网换流load commutation ——负载换流loop current ——环流。

专业英语13章电气工程英语翻译第一篇：专业英语13章电气工程英语翻译12.3 Grounding of Electrical SystemsIn general, most electrical systems must be grounded.The purposeFig.12.4 Secondary high-voltage radial distribution system of grounding is to limit the magnitude of voltage caused by lighting, momentary surges, and accidental contact with higher voltages.System grounds must be seaweed to provide a path of minimum impedance in order to ensure the operation of over-current devices when a ground fault occurs.Current should not flow through the grounding conductor during normal operation.Direct-current systems generally have the grounding conductor connected to the system at the supply station, and not at the individual service.Alternating-current systems, on the ether hand, must be grounded on die supply side of the main disconnect al each individual service.For specific information an the location and methyl of funding, refer to NEC Article 250.(a)Secondary high-voltage distribution system;high-voltage radical.low-voltage loop(b)Consumer distribution system with high-voltage and low-voltage loops Fig.12.512.4 Grounding of Electrical EquipmentMetal conduit and cases which enclose electrical conductors must be grounded.If the ungrounded(hot)conductor comes in contact with a metal enclosure which is not grounded, a voltage will be present between the enclosure and the ground.This presents a potential hazard.Persona comic in contact with the enclosure and ground will complete a circuit.All non-current-carrying metal parts of electrical installations should be tightly bonded together and connected to a grounding electrode.Good electrical continuity should be ensured through all metal enclosures.The current caused by accidental grounds will be conducted through the enclosures, the grounding conductor, and the grounding electrode to the earth.If the current is false enough, it mill cause the over-current device to open.12.5 Ground Fault ProtectionA ground-fault protector(GFP)is a device which senses ground faults and opens the circuit when the currant to ground reaches a predetermined value.A ground-fault circuit interrupter(GFCI)is a device which opens the circuit when very small currents flow to ground.There is no way to determine in advance the impedance of an accidental ground.Most circuits are protected by 15 A(ampere)or larger over-current devices.If the impedance of a ground fault is low enough, such devices will open the circuit.What about currents of less than 15 A? It has been proven that currents as small as 50 mA through the heart, lungs, or brain can be fatal.Electrical equipment exposed to moisture or vibration may develop high-impedance grounds.Arcing between a conductor and the frame of equipment may cause a fire, yet the current may be less than 1 ampere.Leakage current caused by dirt and /or moisture may take place between the conductor and the frame.Portable tools are frequently not properly grounded.and the only path to ground is through the body of the operator.The ground-fault circuit interrupter was developed to provide protection against ground-fault currents of lessthan 15 A.the GFCI is designed to operate on two-wire circuits in which one of the two wires is grounded.Thestandard circuit voltages are 120 V and 277 V.The time it takes operate depends upon the value of the ground-fault current.Small currents of 20 mA or less may flow for up to 5 s before the circuit is opened.A current of 20 mA will cause the GECI to operate in less than 0.04 s.This time/current element provides a sufficient margin of safety without nuisance tripping.The GFCI operates on the principle that an equal amount of current is flowing though the two wires.When a ground fault occurs, same of the currant flowing through the ungrounded(hot)wire does not flow through the grounded wire;it completes the circuit though the accidental ground.The GFCI senses the difference in the value of current between the two wires and opens the circuit.GFCIs may be incorporated into circuit breakers installed in the line, or incorporated into a receptacle outlet or equipment.Ground-fault protectors are generally designed for use with commercial and/or industrial installations.They provide protection against ground-fault currents from 2 A(special types go as low as 50 mA)up to 2 000 A.GFPs are generally installed on the main, submain, and/or feeder conductors.GFCls are installed in the branch circuits.GFPs are generally used for three-wire, single-phase and for three-phase installations, while GECls are used for two-wire, single-phase circuits.A ground-fault protector installed on supply conductors must enclose all the circuit conductors, including the neutral, if present.When operating under normal conditions, all the current to end from the load flows through the circuit conductors.The algebraic sum of the flux produced by these currents is zero.When a phase-to-ground fault occurs, the fault currents returns through the grounding conductor.Under this condition an alternating flux is produced within the sensingdevice.When the flux current reaches a predetermined value, the magnetic flux causes a relay to actuate a circuit breaker.Sometimes the GFP is installed on the grounding conductor of the system.Under this condition, the unit senses the amount of phase-to-ground current flowing in the grounding conductor.When the current exceeds the setting of the GFP, it will cause the circuit breaker to open.The ground-fault protector is actually a specially designed current transformer connected to a solid-state relay.12.Three-Phase SystemsThe various three-phase systems in normal use will lie described.Under ideal conditions, these systems operate in perfect balance, and if a neutral conductor is present it carries zero current.In actual practice, perfectly balanced systems are seldom encountered.The electrical worker, therefore, must be to calculate values of current and voltage in unbalanced systems.Single-phase loads are frequently supplied from three-phase system.The single-phase load requirements vary considerably, making it virtually impossible to maintain a perfect balance.In a balanced three-phase system, the currents in the three lines are equal.The currents in the three phases are also equal.In other words, ILX=ILY=ILZ and Ip = Ip = Ip.if, however, ILX≠ILF≠ILZ, then IPX≠IPY≠IPZ and the system is unbalanced(see Fig.12.6).To calculate the line currents in an unbalanced three-phase system, the method in the following example may be used.Example 1Three pure resistance, single-phase loads are connected in a delta configuration across a three-phase supply, as illustrated in Fig.12.6.Load X requires 30 A, load Y requires 50 A, and load Z requires 80 A.Calculate the current through each line wire.Example 1 applies to loads of 100 percent power factorconnected in delta.With loads of different power factors, the phase angle will vary from 120°.For a wye connection, the line current is equal to the phase current.Some connections may be a combination of singe-phase and three-phase loads.Under these conditions, the phase angle between three-phase load and the single-phase load must be considered.12.7 Harmonic Effect of Fluorescent Lighting FixturesMost distribution systems in tile United States and Canada operate on a frequency of 60 Hz.certain types of electrical equipment produce secondary frequencies are multiples of the supply frequency.These secondary frequencies are called harmonics.For example, the second harmonic of 60 Hz is 120 Hz, the third harmonic is 180 Hz, and so onThe alienating flux developed by transformers, used in the ballasts of fluorescent lighting fixtures, produces a voltage which has a frequency of 180 hertz.This results in an additional current flowing in the supply conductors.The value of the current in the phase conductors is usual about 25 percent of the supply current.This third harmonic current adds to the supply current, causing a greater heating effect in the conductors.This increased heating effect is rather small, possibly in the vicinity of 380% greater than if the third harmonic current did not exist.CAUTION: When installing supply, feeder, and branch circuit conductors for heavy fluorescent loads, the size of the neutral conductor should be at least equal to that of the phase conductors.第二篇：电气工程专业英语1.It is conventional..B positive2.Electric..D amperes3.The energy..C voltage4.The plus..A voltage polarity5.According..B absorbed1.The switching..C the off2.The typical..B 0.7V3.The power..D highr4.The rate..C power 1.The DC-AC..B direct2.The Buck...C current3.The PWM...B pulse4.The gain..B the input control voltage 1.High power..C three2.The output..B sinusoidal3.The constant..B ac voltage4.Voltage..C inductive5.Output amplitude..B pulse-width1.A computer work..A a series of stored2.A keyboard..B an input3.The computer network..C a local4.A computer that..B client5.A hard..C a storage1.Logical..B the ALU 2.The 16..B sixteen bits3.A microprocessor..A more rapidly4.Data stored..B permanently5.The basic..C CMOS1.is used..C a network card2.are pri..C AGP slots3.The network..B LCDs4.Image..B dot5.Printer..A an ink1.The first complete..B1882 a dc2.The first three..C 18933.Power system..A transmission4.In North..C60hzcan..A the HVDC1The protective..C tripping2.When the rip..B switched off3.Any protection..A two4.Theof..D reliability5.The protective..B zeroThe concept of electric charge is电荷的概念是用来解释所有电气现象的基本概念。

CIRED2005 Session No 3REACTIVE POWER COMPENSATION AND VOLTAGE CONTROL IN JINAN POWER DISTRIBUTION SYSTEMYutian LIU Jiachuan SHI Xia QIANSchool of Electrical Engineering, Shandong University Jinan Electric Power Company Jinan 250061, China Jinan 250012, Chinaliuyt@ qianx@INTRODUCTIONThe main reasons of voltage and reactive power problems in Jinan power distribution system are unreasonable network structure, large load change ranges, lack of reactive power compensation and voltage regulation means. Based on engineering practice and current technology, some measures are presented for solving these problems. An optimal voltage regulation method is proposed for medium and low voltage (from 10kV to 0.4kV) distribution network. The regulating frequencies of no-load tap changers and capacitor banks are properly limited. Operating conditions are selected to cover load variations during a long period of time. The combinatorial optimization problem about tap-changers and shunt capacitors is solved by tabu search technology to get the global minima or acceptable results in reasonable time. The simulation results of a practical network in Jinan, China, show that the method is effective in improving the voltage profiles.VOLTAGE AND REAVTIVE POWER CONDITION IN JINAN POWER SYSTEMJinan city is the capital of Shandong province in east China. With increasing rapidly in recent years, the biggest electric power load is about 2200MW in 2004. The electric power is mainly supply from three power plants and one 500kV substation. There are 11 220kV substations, 24 110kV substations. More than 400 10kV lines supply about 1500 10kV/0.4kV power distribution transformers in the urban district.With social and economic development in Jinan city, the load difference between peak and valley time becomes so large that the voltage regulation is not enough to meet all the operating conditions. There exist usually lower voltage in peak time and higher voltage in valley time in the power transmission and distribution networks. The main reasons are unreasonable network structure, large load change ranges, lack of reactive power compensation and voltage regulations.Based on engineering practice and current technology, some measures are outlined for solving these problems. They are paying attention to the reactive power planning, building the reactive power management network, enforcing the power transmission network, keeping the voltage regulating equipments in good condition, improving the distribution network, adding reactive power compensation and voltage regulation devices, paying attention to voltage measurement, improving local reactive power compensation for large users, enforcing harmonic management and keeping high available rate of capacitors. With these measures being taken, the voltage qualified rate is improved and the active power loss is decreased. However, it is need to research in depth the reactive power compensation and voltage management in medium and low voltage distribution networks to ensure the voltage quality of 0.4kV end users.VOLTAGE REGULATION METHODVoltage regulation and/or reactive power optimization aims to improve voltage profiles and reduce active power losses by regulating reactive power flow distribution. Currently, little or no generator is installed in medium and low voltage distribution systems in Jinan, China. Therefore, the regulation means in distribution systems are mainly transformer tap-changers and shunt capacitors, which are discrete variables.Voltage regulation and/or reactive power optimization in distribution system in this paper is to form a regulation scheme for locations and sizes of capacitors and positions of transformer tap-changers to improve voltage profiles and minimize active power loss and. Therefore, it is a constrained combinatorial optimization problem.In most of the papers on voltage regulation and/or reactive power optimization in 10kV or higher voltage distribution networks [1-5], on-load tap-changers and shunt capacitors can be adjusted several times a day according to load variations. However, most of the transformers are of no-load tap changers and fixed shunt capacitors cannot be adjustedCIRED2005Session No 3automatically in the medium and low voltage (10kV-0.4V)distribution network in Jinan, China. Therefore, a medium voltage (10kV) distribution feeder based voltage regulation method aimed to improve secondary side voltage (0.4kV)profiles is presented in this paper. The regulating frequency of tap-changers and shunt capacitors is limited to several times a year by considering the variation of loads during a long period of time.Voltage Profiles AssessmentA trapezoid membership function is introduced to evaluate the network voltage profiles. The two main aims of var/voltage optimization, decreasing active power loss andimproving voltage regulation, may conflict. Generally,reactive power optimization trends to minimize active power loss by increasing voltage to upper voltage limit, which is not acceptable in practice considering variations of loads and source node voltage. If the voltage constraints are treated as “hard” constraints, that is, no voltage violation is allowed; it may be hard to find a feasible solution, especially considering two or more operating conditions. Thus, the voltage profiles constraints are considered as an objective by introducing a membership function to evaluate voltage eligibility of each node and voltage profiles. The membership function for each node voltage is described as01100011011 1 0 upper upper upper i i upper upperlower lower upper i i lower lower volt i lower upper i V L L V L L L V L L V L F V L L L V L (others)­ ° °° ° ® °°d d °°¯ (1)Where, F volt (V i ) is the voltage eligibility membership function for node i , L 0upper and L 0lower are unacceptable voltage limits,L 1upper and L 1lower are acceptable voltage margins, respectively.The value for voltage profiles assessment is the mean of the membership values of all nodes.Active Power Loss AssessmentDifferent from the membership function for voltage profiles evaluation, there is not a standard or limit for active power loss [4]. The active power losses in a radiating distribution network will decrease if all reactive power loads are fully compensated and tap-changers adjusted to their upper voltage limits. In such an imagined operating condition, power flow is calculated and the active power loss, P l_min , is considered as the minimum power loss. Each active power loss of trialsolutions, P l , is assessed by the following membershipfunction_min _min _min _min _min 0 2 22()1 l l_ori l l l ori lossl_l l_ori l l l oril l_P P P P P FP P P P P P P P­! ° ° d d ® °° ¯(2)Where F loss is the membership function for active power loss,P l-ori is the active power loss before optimization compensation and regulation, P l_min is the minimum active power loss in some imagined operating condition.Voltage Imbalance AssessmentVoltage imbalance is common in distribution networks because of the unbalanced impedances, single-phase loads,phase-to-phase loads and unbalanced three-phase loads.According to the symmetrical component theory, an unbalanced system can be decoupled into three balanced systems, that is, positive sequence, negative sequence and zero sequence system.As a part of power quality, the unbalance factor for each load should not be bigger than 1.3% in China. The unbalance factor for three-phase line-to-line voltage readings is defined by the IEC asH and2222444cabcabca bc ab VV VV V VE (4)Where İ is the unbalance factor, V ab , V bc and V ca are the line-to-line voltages, respectively.The membership function for the İ is defined as10101001 0 i unbal i i i İİx F İİİİİH H H H ­d °° ® °°t ¯(5)Where İi is the unbalance factor of node i , İ0 is anunacceptable unbalance factor limit and İ1 is an acceptable unbalance factor margin.Capacitor PlacementCIRED2005Session No 3Properly placed shunt capacitors can improve power factor and voltage quality, and reduce reactive power demand so that active power loss. The nodes with violated voltage-unbalance limits or much varying reactive power demands are considered as to compensate with automatic-switched capacitors (ASC). While fixed shunt capacitors (FC) are placed according to the following sensitivity coefficient of active power loss to reactive power injection under the heaviest load condition _lossi inject iP SC Q ww (6)Where SC i is the sensitivity coefficient, P loss is the active power loss of the branch, Q inject_i is the reactive power injection at node i .The nodes with highest sensitivity coefficient are pre-selected as the nodes to be compensated.Objective FunctionThe objective function including voltage profiles, active power loss and voltage unbalance under operation condition m is represented as_ obj m volt loss unbal m F F F F D E J (7)Where F obj_m is the objective function for operating condition m , Į, ȕ and Ȗ are weight factors for the three objectives.Thus, the voltage regulation problem is described as the following_1min maxmaxMax.. 0Mobj obj m m k k k cj cj F F s t T T T Q Q d d d d ¦ (8)Where M is the number of operating conditions, T k is the ratio of transformer k , Q cj is the reactive power of capacitors at node j . The restriction of power flow is not listed here.Optimization AlgorithmTo get the global minima or acceptable results in reasonable time, above-mentioned combinatorial optimization problem can be solved by a genetic algorithm or tabu searchtechnology. The process of the tabu search adopted is described as following.i)Read in initial data, including impedance of feeders,loads, regulation variables and inequality constraint conditions. Code the regulation variables.ii) Generate initial solution. Set the regulation variablesrandomly without breaking the constraint conditions,including power flow restriction. Calculate the objective function f(X), and set best solution vector X opt as X which is consisting of T k and Q cj .iii) Generate a group of trail solutions, X 1, X 2, … , X k , by“move” from X , and calculate the responding values of objective function, f(X 1), f(X 2), …, f(X k ).iv) Search neighborhoods. Get the best one, X* , from thetrail solutions. Update X with X*, if X* is not in the Tabu list, or X* fits the aspiration criteria. Try the next solution, if the former one cannot update X .v) Update Tabu list. Push the record of reversed move intothe Tabu list, which is a FIFO (First-In-First-Out) stack.vi) Update X opt with X*, if f(X*) is better than f(X opt ).vii) Terminate condition. Stop optimization and outputresults if f(X opt ) has not been improved for several iterations or the given maximum iteration number is met. Otherwise go to step iii) to continue.Software PackageA Client/Server software package based on the proposed approach is implemented in C++ with man–machine interactive procedures, which has following distinct features. i) Tabu search optimization technology is utilized in thesoftware to solve the optimization problem. Compared with the traditional mathematical optimization algorithms,the heuristic searching and optimizing technique can avoid trapping in local optimums and get the global optimum with high probability or acceptable solutions in reasonable time.ii) The package employs two kinds of databases. Customerdatabase is used to store the data of various customer networks, including node data, line data and transformer data. Common database is used to store the information of common devices, including line common data and transformer common data. The data of customer database can be inputted by users or selected from common database directly. Users can get data via ODBC from the SCADA system, which enhances the online optimization ability of the software package.CIRED2005Session No 3SIMULATION RESULTSThe effectiveness of the proposed method is verified by the application to a practical distribution feeder shown as Fig.1 in Jinan, China. Data are sampled by the SCADA system every15 minutes.Fig.1 Distribution network structureThree-phase power flow [5] is calculated by a forward-backward sweeping algorithm. All transformers in this network have no-load tap-changers (NLTC), which are of 5positions (1±2.5%×2). All the original positions are 3, that is,all the ratios are 1 p.u. The phase-to-neutral voltage upper and lower limits for 220V distribution networks are 7% (235.4V)and -10% (198V) respectively.The node (6000#) with most unbalanced reactive power demands is selected to compensate with nonsymmetrical auto-switched capacitors. So the reactive power loads at this node are almost fully compensated.Some of optimization results are given as following. Tap changers of all the transformers are regulated from position 3to position 1, that is, to decrease the ratios from 1 to 0.95 in p.u. Three transformers with biggest sensitivity values are selected to be compensated. They are node 6010#, 6007# and 6008#. The compensation capacities are 18, 12 and 18 kVar,respectively. Transformer 6010# is of the smallest VA capacity (250kVA), whose impedance is bigger than that of the others (315kVA or 400kVA). After optimization, the voltage profiles are improved quite effectively with small active power loss decrease. In other words, all the voltages at different conditions are in the permitted range.CONCLUSIONSThe main reasons of voltage and reactive power problems in Jinan power distribution system are outlined. Proper measures are presented based on engineering practice and current technology.An optimal voltage regulation method is proposed for medium and low voltage distribution networks. The reactive power optimization problem is formed as a multi-object optimization problem, which aims to improve voltage profiles, decrease active power losses and balance voltage imbalance. Membership functions are introduced to balance different objectives. The regulating frequencies of no-load tap-changers and capacitor banks are properly limited.Operating conditions are selected to cover load variations during a long period of time. The combinatorial optimization problem is solved by tabu search technology to get the global minima or acceptable results in reasonable time. The simulation results of a practical network show that the method is effective in improving the voltage profiles.REFERENCES[1] Y. Liu, et al. 2002, “Optimal voltage/var control in distribution systems”, Int J Elec Power, vol.24, 271-276.[2] Z. Hu, et al. 2003, “V olt/Var control in distribution systems using a time-interval based approach”, IEE P-Gener Transm D, vol.150, 548-554.[3] S. F. Mekhamer, et al. 2003, “Application of fuzzy logic for reactive-power compensation of radial distribution feeders” IEEE T Power Sys, vol.18, 206-213.[4] C. Su, et al. 1996, “A new fuzzy-reasoning approach to optimum capacitor allocation for primary distribution systems ”, Proceedings Industrial Technology, IEEE pp.237-241.[5] W. Lin, et al. 1999, “Three-phase unbalanced distribution power flow solutions with minimum data preparation”,IEEE T Power Sys, vol.14, 1178-1183.。

英文原文Industrial enterprises of reactive power compensationAbstractThe improvement of industrial enterprises is to improve the power factor of electric power efficiency,an important means of saving energy. In this paper, theoretical analysis and application examples of the industrial enterprises,the significance of reactive power compensation and the role and view of the current power system,industrial enterprises,the problems for the proposed improvements and measures.IntroductionIn industrial enterprises,the vast majority of electrical equipment belongs to perceptual load，these devices in operation to absorb a large number of reactive power. An increase in reactive power supply system power factor to lower system voltage drop to occur,electrical equipment not fully utilized, increasing line losses and lower-powered equipment,power supply capacity and so on. In situ reactive power compensation and thus improve the power factor of the Energy Conservation has extremely important significance.The choice of method of compensationCompensation for reactive power compensation is divided into centralized and decentralized compensation for three kinds of compensation and in situ. Focus on compensation,that is,high and low voltage power distribution set up by several groups within the capacitor，capacitor connected to the power distribution bus,the compensation for the distribution of power within the reactive power,and to reach the required value of the total power factor above. This method of compensation can compensate for high and low voltage bus routes prior to the reactive power,which is equivalent to the reactive power source to move the electricity distribution companies,allowing users to power the system requirements for reactive power hasbeen reduction in the electricity sector to achieve the required power factor. And their distribution within the enterprise bus following the line of transformer and reactive power compensation can not play a role,there is still a large number of reactive power line flows within the enterprise and generate losses. Dispersion compensation is the capacitors were installed at various workshops at the switchboard,which will enable installation of distribution transformer and the substation to the plant lines can be due to a decrease in reactive load compensation effect. Local compensation is the reactive power compensation device directly connected to the induction motor terminals on the side or into the line. Focus on compensation methods used in the capacity of capacitor compensation or in-place than the grouping of compensation should be small,its utilization rate is even higher disadvantage is the change in distribution has not been compensated by the feeders,only lightened the load reactive power grid. Dispersion compensation in the way the utilization of capacitor compensation than the in situ high,so the total requirement of compensation is smaller than the spot is an economical and reasonable remedy. Reactive power compensation should follow the "overall planning,rational distribution，classification of compensation,in-place balance; focus on compensation and dispersion compensation combine to spread-based compensation; high compensation and low voltage compensation combined with low-pressure-based compensation; Regulator combined with lower losses,down are the main loss "principle [1].Compensation capacity to determineIn the power grid in the reactive power consumption is a big，about 50% of the reactive power consumed in transmission，transformation and the device，50% of the consumed electricity users. In order to reduce reactive power consumption，it is necessary to reduce the reactive power in the grid where flow. The best way to start from the user to increase reactive power compensation,improve user load power factor,so thatGenerator reactive power can be reduced and the reduction of transmission，transformation and distribution equipment in the reactive power consumption，so as to achieve the purpose of reducing wear and tear [2]. Compensation for reactive powercapacity of Qc for22121111cos cos c av Q P ϕϕ⎡⎤=---⎢⎥⎣⎦Load changes can be decided according to the static or dynamic compensation mode. When the load change is relatively stable,we should use the static method of compensation,which can not only reduce the line losses ， and investment; when the load change is large ， dynamic compensation method should be used ， stable voltage[3].Reduce line lossesIs located at a rated voltage,active power is constant,due to power factor changes,the line loss rate of change ΔP% for the212cos %1()100%cos P ϕϕ⎡⎤=-⨯⎢⎥⎣⎦ As can be seen from Table 1 to improve the power factor in lowering power consumption,improving economic efficiency plays an important role.Table 1 Power factor and power loss percentage of the corresponding dataI f a constant active power condition,the original power factor cosφ1 of0.59,compensated power factor cosφ2 of 0.98,its line loss rate reduction ΔΡ% to 64%. Dynamic compensation device.Group to track the power capacitor compensation ， power factor can be different from the stability provided in the context of the power factor to achieve adequate compensation purposes.Lines ， transformer capacity increaseLines,transformer capacity increased ΔS for the12cos 1cos S S ϕϕ⎛⎫=⨯- ⎪⎝⎭Additional compensation device,may improve the power factor,power factor on the business of direct economic benefit is obvious. Because the state electricity system,starting from the rational use of energy,according to the power company to adjust the price due to high and low values. The compensation device for enterprise and the entire power system economic operation all have significant economic effects .To improve the voltage qualityTo improve the voltage quality is the dynamic reactive power compensation equipment installed around the role of place in the line voltage compensation has increased slightly . 12211100%U U tg x U Q R tg xϕϕ-=⨯=+ Where tgφ1 - compensation device is not installed before the φ1 angle tangent;tgφ2 - compensation equipment installed after t he φ2 angle tangent;R ， x --- line resistance ， reactance.Industrial enterprises for the power system problems and solutionFig 1 for a diagram of power supply systems for heavy machine tool plant. At present,the total capacity of the plant transformer 17660kV A,a total of 20 transformers (1 # ~ 20， # transformers),each transformer capacity range of 50 ~ 1250 kV A ， changing the ratio of 10kV / 014kV . Transformer low voltage side of the load is mainly motor ， shown in the M1,M2 Mn shown. In general the rate of transformer load is basically maintained at 28% ~ 29%, and the maximum load of 7000kW.High and low voltage compensation to replace a combination of high concentration of compensationFrom the figure we can see the plant supply network focused on high-voltagepower factor compensation is compensation that is only in the high-voltage busbar 10kV substation capacitor banks on the pick,while the low pressure has not taken any compensation measures. The fixed capacitor compensation method there have been compensation or due compensation, and right below the second power supply bus power factor compensation circuit does not work. As the low power factor caused by the line losses and transformer equipment is a big loss,so compensation as far as possible when grading,installation of capacitors near the load. Therefore proposed that the high side to focus compensation and dispersion compensation for low-voltage side of a combination of method of compensation .Figure 1Power Supply System of a Heavy Machine Tool Plant diagramTo change the power supply as much as possible to avoid the "big horse-drawn cart" phenomenonIn making our selection,we should consider leaving a certain margin,to prevent heavy damage to equipment when,so most of the time caused by equipment,and severe underrun underrun the formation of the "big horse-drawn cart" Run. As the plant load factor of the transformer is basically 28% ~ 29%,and shows the transformer capacity is too large,transformer capacity can not be fully utilized,not only a waste of investment in equipment has increased the power loss. Rational choice by the transformer capacity and electrical equipment to reduce or limit the light-load or noload time to prevent the "big horse-drawn cart" phenomenon.To avoid the no-load operation of equipmentAt present，the plant is running a serious load of some equipment. Improving the power factor,the first consideration should be given a reasonable run the equipment to improve power factor of power the device itself. The plant main load is AC motor,its power factor load with it change, motor idling,the power factor of about 0.1 ~ 0.3 between the rated load at 0.8 ~ 0.85 between the motor and thus should be made near the rated load state run. We should improve the motor power factor,the simplest way is to use capacitors and electric motors in parallel,so to avoid the no-load operation device is to improve the power factor equipment, an important way.中文译文工业企业无功补偿摘要改善工业企业用电的功率因数是提高用电效率、节约电能的重要手段。

附录附录一英文资料Recent advances in var compensatorsG]~ZA JOOS . Department of Electrical and Computer Engineering, Concordia University 1445, de Maisonneuve W, Montreal, Canada H3G 1M8e-mail: geza@ece.concordia.caAbstract. Static var compensators have been, for many years, an essential co mponent in the operation of power transmission systems. They are part of a fam- ily of devices known as Flexible AC Transmission System (FACTS) devices. The advent of large capacity force-commutated semiconductor switches allows many developments in power electronic converters to be applied to the implem- entation of high power compensators. This paper describes the principles of co- ntrolled reactive power compensation, particularly in the context of power syst- ems. It focuses on active static power converter-based compensators and discu- sses issue related to the power circuit topology and control techniques including the impact of Pulse Width Modulation (PWM) techniques. Compensators based on current and voltage source converters and on ac controllers, both in the shunt and series configurations, are covered. Methods to enhance power capacity usin -g multi-level and multi-pulse arrangements are discussed.Key words. Reactive compensation; power electronic converters; powers ystems.1.IntroductionReactive power (var) compensation has long been recognized as an essential fun ction in the operation of power systems. At the distribution level, it is used to i- -mprove the power factor and support the voltage of large industrial loads, such as line commutatedthyristor drives and electric arc furnaces. Reactive power co- mpensation also plays a crucial role at the transmission level in supporting the l- -ine voltage and stabilizing the system. Rotating synchronous condensers and m- echanically-switched capacitor and inductor banks have been replaced in the 19 70s by thyristor-based technologies: in typical installations, a thyristor-contro- lled reactor (TCR) provides variable lagging vars, and fixed or thyristorswitched capacitors (TSC) provide the leading vars. The combination of both devices in parallel allows continuous control of vars over a wide range of values, from lea -ding to lagging vars (Gyugyi 1979). A large number of units have been succes -sfully installed and operated for many years. At the same time, the potential of var compensators based on static power converters have also been recognized an -d a number of configurations proposed and investigated (Gyugyi 1979). However, thyristor technology only allows the implementation of lagging var generators, unless complex force-commutation circuits are used. This drawback has been eliminated with the introduction of Gate Turn-Off (GTO) thyristors (La -rsen et al 1992). This has allowed the development of a number of configuratio -ns based on the use of synchronous voltage sources (Gyugyi 1993). Prototype GTO-based var compensation units, known as STATCOMs have been installed and tested by utilities (Schauder etl 1995). The STATCOM and other static var compensators have recently been grouped, together with other types of transmiss -ion system control devices, under the heading of Flexible AC TransmissionSystem (FACTS) devices.Reactive power compensators are typically connected in shunt across transmis -sion and distribution systems. An alternative connection, the series connection, has recently received much attention from utilities (Gyugyi et al 1996). Techno -logical solutions have been developed to solve problems associated with insula -ting the equipment from ground and the full potential of series connections can now be exploited. The latest development in var compensation technology has b -een the combination of series and shunt static compensators into one unit, know -n in the area of power systems under the name of Unified Power Flow Controll -er, or UPFC (Gyugyi 1992).Static power converters have been successfully applied to a large number of power conversion problems at low and medium power levels. However adapting these solutionsto high power transmission and distribution levels raises special issues. Although the capacity of power semiconductor switching devices has gra -dually increased, large ratings still require combining devices in series and par -allel. In addition to the large power handling capacity, static compensators must have very high efficiency, since losses have a negative impact on both the initial and operating costs of the power system. Switching losses are therefore a prima -ry concern and switching frequencies must therefore be kept low. This may res -ult in large harmonic waveform distortion, unless special power circuit configu -rations are used.This paper reviews the various methods available for generating reactive pow -er (var) by means of force-commutated static power converters, taking into acc -ount the above constraints. It discusses topologies suitable for use with devices such as GTOs and the more recently available high power IGBTs and addressesswitch gating issues, including the use of Pulse Width Modulation (PWM) tech -niques. Methods for designing high power converters suitable for transmission level compensation are presented, particularly multilevel and multi-module top -ologies.2. Principles of var compensationVar compensation can be viewed as the injection of reactive power, leading or lagging, into the ac system. In its simplest form, reactive power injection is ach -ieved by inserting fixed capacitors or inductors in either series or shunt into the ac system. Assuming a compensation reactance Xc is inserted in a transmission system, the generated var Qc is derived as follows.Figure 1. Principles of vat compensation in transmissi6n systems. (a) Shuntcompensation. (b) Series compensation.(a) For the shunt connection, figure la,a reactive current Icq is generated, allowing in particular line voltage support at the point of connection, Vc:cq 2//C CC C C I V X Q V X ==(b) For the series connection, figure lb the reactive impedance Xcpartially com-pensates the line reactance, and a reactive voltage Vcq is inserted in series, the current Ic being the line current:cq 2C CC C C V I X Q I X ==In addition to the lack of controllability of the reactive power injection, fixed capacitive compensation can lead to ac system instability, such as in the pheno -menon known as subsynchronous resonance, or SSR, associated with series c- ompensation (Ooi & Dai 1993; Gyugyi et al 1996). In order to control the amo -unt of reactive power injected, the reactive impedance must be varied. Equiva- lently, a variable current or variable voltage is injected into the system, emulat- ing a variable reactance, figure 1 b.The apparent reactive impedance of a fixed element can be varied using ac s- witches, or ac controllers. On the other hand, the current or voltage required to e -mulate a variable reactance can be injected into the ac system by means of syn -thetic sources, which can be realized using static power converters (Agaki et al 1984; Campos e t a l 1994). In addition to providing reactive power, these active compensators can also supply real power, either transiently or for a number of periods of the ac supply. This real power can be used to dampen power system oscillations or temporarily support the power system voltage under fault condi -tions. Furthermore, since the compensator is fully controllable, resonant freq -uencies associated with the use of capacitors are eliminated and the potential for instability suppressed.Figure 2. Thyristor-controlledv ariable reactance compensators.(a) Thyristor-controlled reactor (TCR) and thyristor-switched capacitor (TSC) shunt compensator• (b) Transfer characteristics of a TCR with fixed capacitor. (c) Thyristor-controlled series capacitor compensator (TCSC).3. AC controller-based structures3.1 Conventional thyristor-controlled reactorThe basic scheme, figure 2a, consists of an ac controller which varies the appa- rent inductance of the inductor as reflected onto the ac line (Gyugyi 1979). The thyristor-controlled reactor (TCR) provides continuously controllable lagging vars and is biased using fixed, or more often, thyristor-switched capacitors(TSC). The injected vars can therefore be continuously adjusted from leading to lagging, figure 2b. However, the var injection or voltage regulation capability of the com -pensator is limited by the value of the reactance and is therefore line voltage de-pendent, figure 2b. Advantages of the system however include ruggedness, high efficiency, good dynamic performance and competitive cost. The disadvantages include injection into the line of large low frequency harmonic currents, domin- ant being the 5th and 7th components (300 and 420 Hz for a 60 Hz system) for the basic ac controller. Harmonics can be moved to higher frequencies by para- lleling units and using special transformer configurations. Harmonic currents ca -n be reduced by means of tuned LC filters. These however are costly and can c -ause voltage oscillations resulting from the added system resonant frequencies.3.2 Force-commutated ac controller structuresAn alternative to the thyristor-based ac controllers is the force-commutated ac controller, figure 3a (Jin et a11994; Venkataramanan & Johnson 1997). The use of force-commutated switching devices removes the requirement for operating the converter in synchronism with the ac supply and allows gating the switches more than once per cycle. Arbitrary gating patterns can be implemented, partic -ularly PWM patterns (Jin et a11994). The principles of PWM pattern generat- ion are explained in § 6.2. Assuming the inductor current is sinusoidal, a pattern with constant duty cycle yields ac line side currents that only contain harmonics around the switching frequency and its multiples. This pattern is simple to impl -ement and allows control of the equivalent inductance; therefore, the amount of vars absorbed can be varied from 0 to a maximum value. Since losses associated with switching large currents at high voltages increase significantly with switch -ing frequency, this frequency must be kept low, typically a few hundred hertz for GTOs. In order to reduce the distortion of injected currents, while keeping the switching frequency low, elementary modules are connected in parallel, figure 3b, and gated so that harmonics are minimized . This also allows therealization of var compensators of large ratings (Lopes et al 1996).Figure 3. Variable reactance scheme based on force-commutated ac controllers (Bias capacitorsart not shown). (a) Basic ac controller structure.(b)Multi-module converter附录二中文翻译无功功率补偿的最新进展作者：G]~ZA JOOS ，电气与计算机工程系，肯考迪娅大学， 1455年纳芙钨，加拿大蒙特利尔H3G 1M8 ，电子邮箱：geza@ece.concordia.ca摘要静止无功补偿器已有多年的发展历史，是电力传输系统中一个必不可少的环节。