跨海引水工程的控压措施研究

该文针对舟山.大陆跨海引水工程的特点,对舟山及宁波的陆上引水管道部分,采用空气阀以控制负压;对海底跨海管道的控压措施进行多种方案的研究和分析,最终选定以加大管道人海口处缓冲池容积及该处输水泵的转动惯量的方案为跨海段的控负压措施.经工程实施运行,实践证明效果良好,文中给出了计算模型、过渡过程分析及方案的确定.     

湋水倒虹钢筋混凝土管裂缝原因分析及处理

钢筋混凝土压力输水管的抗裂性问题,是水利水电建设中一个引人注目的问题。宝鸡峡湋水倒虹工程采用大直径钢筋混凝土管,其所承受的水头高达50米,于建成运用后产生纵向贯通裂缝。本文以该工程为例,对管道设计、施工情况及运用过程中出现裂缝的情况作一介绍并指出:由于设计上忽略了外露式管道运用期的温度应力,加之管顶混凝土的施工质量相对较低,是导致管道产生纵向贯通裂缝的主要原因。经对开裂后管道的安全度进行分析,决定采用管外复盖降温与管内防渗方案进行处理。管道裂缝处理后已运用多年,实践证明这一措施是成功的。     

西气东输抚州分输压气站压缩机组辅助系统防晃电改造

正西气东输是国家重点工程,主要为全国各地输送清洁的天然气能源。压缩机作为长输天然气管道的"心脏",能为管道天然气增压,其运行的稳定性对管网的安全运行至关重要。压缩机是比较复杂的大型增压设备,分为燃驱压缩机和电驱压缩机,每台压缩机均有复杂的辅助系统。晃电指雷击、短路或其他原因造成的电网短时电压波动或短时断电现象。随着电网并网、环网规模的日益扩大,电源晃电越来越频繁。     

单控制器轮驱电动汽车驱动装置

分析了轮驱电动汽车(EV)驱动系统的结构与工作原理.针对轮驱电动汽车两个电机协调控制的要求,采用XE164-FM单控制器实现两轮毂电机的控制,解决了轮驱电动汽车CAN控制的延迟性和不可靠性的问题.介绍了轮驱EV电子差速算法和无刷直流电机的控制方法,设计了基于XE164-FM控制的轮驱电动汽车驱动系统.试验结果表明,此方案可以方便、有效地对两个电机进行协调控制,证明了此方案的可行性和正确性.     

发电厂供热抽汽管道安全阀的选型

介绍了供热抽汽管道安全阀的功能和型式,结合太原钢铁(集团)有限公司自备电厂汽轮机供热抽汽管道安全阀选型计算进行了详细说明,同时对选型方案做了详细的比选并最终确定了适合工程需要的安全阀型式.     

直驱永磁同步风力发电系统控制策略研究

对直驱永磁同步风力发电(DDPMG)系统的功率解耦控制技术进行了研究.发电机功率经整流-逆变后接入电力系统,在变流器直流侧运用boost电路实现最大功率跟踪(MPPT);当风速高于额定值时,运用PI调解器完成变桨距控制;在风力发电网侧逆变器动态数学模型基础上,采用空间矢量脉冲宽度调制(SVPWM)方式和电网电压合成矢量定向,实现了电流有功分量和无功分量的解耦及功率因数的可调控制.对方案进行了MATIAB仿真研究.结果表明,系统动态响应快,具有MPPT和功率解耦控制功能,验证了方案的可行性和正确性,为直驱永磁同步风力发电系统的进一步研究提供了可靠的理论依据.     

电厂1000MW超超临界机组四大管道设计方案寻优比较

针对华能沁北电厂三期(2×1 000 MW)工程,分析了国内外1 000 MW超超临界机组通用管材的优劣,采用比选的方法对四大管道不同规格方案的运行和投资费用进行分析,同时研究了四大管道的弯管与弯头布置方式,给出了满足该电厂机组的四大管道合理规格和合理布置方式.     

高压加热器疏水排气系统管道设计分析

从参数设定、管道布置及支吊架设置三方面对高压加热器疏水管道及安全阀排气管道设计中的问题进行归纳总结。以某工程2号高压加热器疏水管道为例进行参数的计算和选取,对优化管道布置及支吊架设置给出了相应的方案。     

兴化湾波浪发电技术路线研究分析

介绍了目前福建兴化湾海域的相关特点,接着阐述了波浪能的相关技术路线,分析了各个技术路线特点,最终结合波浪能现有的技术特点和兴化湾海域的相关情况,阐述了直驱式更加适用于莆田兴化湾海域。根据目前直驱式波浪能发电的相关技术方案,指出了兴化湾波浪发电示范工程需解决的技术和工程应用问题,对于促进波浪能在应用工程示范落地具有重大意义。     

基于磁场定向的永磁同步发电机功率控制

在介绍永磁同步发电机(PMSG)数学模型和矢量控制理论的基础上,将传统的永磁同步电动机的矢量控制方法运用到发电机中来.在大功率永磁直驱风力发电变流器研究过程中采用该方法进行了实验研究,通过仿真实验验证了该方案的可行性.     

An electric traction drive for electric vehicles

Problems of expanding the range of speed regulation in electric transport vehicles by replacing gear-shift transmission with a two-channel electric drive comprising two electric motors, each coupled with its own reducing gear units possessing different gear ratios. The output shafts of these reducing gear units are coupled to one differential speed-reduction device. To solve this problem, a mathematical model of the electric-motor drive has been developed and the static characteristics of the individual motors and characteristics of the motors with their output shafts driving one differential speed-reduction device have been determined. Steady conditions of the operation of a two-channel electric drive are considered. To describe real changes in the speed variables, the electromechanical transducer is approximated in the mathematical model with nonperiodic first-order links. The functions of the controlling effects, which are formed on the basis of the criterion of fullest utilization of electric machines with respect to their electromagnetic torque in stable conditions and in transient processes, were determined. Recommendations are given on application of the proposed solution to traction mechanisms, which should meet increased requirements to acceleration of electric-motor vehicles.     

A traction electric drive for electric cars

It is advisable to use a controlled electric drive in electric drives of electric off-road vehicles due to its significant multiplicity of the supported torque (5: 1 and higher) in a low-power mode. Such overloads can be achieved, for example, in electric drives with a field-regulated reluctance machine, not only because of the capacity of the electric machines, but also due to the choice of the drive control system. Analysis of requirements for the electric drive of an electric vehicle is performed, and the influence of the control method on the specific parameters is considered. Analysis of the number of independent control actions in synchronous reluctance electric drives is provided. The possibility of increasing the overload multiplicity of the torque by abandoning the vector control in favor of structures similar to dc drive systems is shown.     

国外电力

1德国10月28日运行其首个海岸风电场,该风电场距离德国北海沿岸大约500 m。装机5 000 kW的示范电场所发电力将导入威廉港天然气和电力电站,足以供5 000个家庭使用。据悉,胡克希尔风电场是将要建设的大型风电场的样板电厂。德国北海     

Think electric

With biofuels being subjected to allegations of hidden carbon costs and causing food shortages in the developing world, it has never been a better time for makers of that other current viable petrol alternative, electric cars, to develop and market them.     

电动汽车充电机对电能计量的影响

建立考虑线路阻抗和配电变压器的电动汽车充电机模型,仿真分析了充电机直流大功率充电和脉冲充电对电能计量的影响。仿真分析结果表明:恒流充电时充电机向电网注入谐波功率,注入功率的大小随充电功率和线路阻抗的增大呈上升趋势,但总体上占基波功率比值很小,为0.012%,对电能计量造成的影响有限;充电功率变化时谐波功率的特点与恒流充电时基本相同;脉冲充电方式下,谐波电流受脉冲充电频率影响较大,高频脉冲充电时含有大量偶次谐波与间谐波,采用积分算法原理进行电能计量的误差大于0.5%。     

Dual-mechanical-port electric machines-concept and application of a new electric

In this article, the various possible structures of a dual mechanical port (DMP) electric machine are explored and operation features discussed. Further, dynamic modeling of the DMP electric machine is presented. In particular, the salient features and suitability of DMP machine to hybrid electrical vehicles (HEVs) are discussed.     

Features of traction electric equipment of prospective electric rolling stock

On the main railways in Russia, two types of current in the contact wire are used: dc voltage of 3 kV and ac voltage of 25 kV with a frequency of 50 Hz. Therefore, prospective electric rolling stock should have double the power. Improving the capacity and structural speed of locomotives is based on the use of asynchronous traction motors (ATDs) with a squirrel-cage rotor allowing increasing the tractive force and the weight of the train and the capacity and speed of cargo delivery, increasing reliability and reducing life cycle costs, and increasing service life. Electrical equipment for such rolling stock should be used when working from either contact system, dc or ac. In this article, the scheme of power circuits is considered using the example of a module of a traction drive in one bogie of dual-system electric locomotives. It is proposed to use the secondary winding of the traction transformer as a choke of the input filter when powered from a dc contact system. Regulation of operation modes of asynchronous traction motors is carried out from static semiconductor converters with a two-tier structure. Input transducers provide the exchange of electric energy between the contact system and the intermediate link of dc voltage, and the output converters regulate the traction motors by changing the magnitude and frequency of voltage on the stator windings of ATD depending on the speed of the locomotive and its operating mode. 4QS input converters and output converters are autonomous voltage inverters of the intermediate ac: in the case of single-phase input and output, they are three-phase. The basic ratios are given to determine voltages and currents of 4QS converters, to determine the variable component of a rectified current 4QS converter, and to formulate requirements for a resonant L₂C₂ filter configured for a frequency of 100 Hz. Expressions are given for determining the ratio of the input power of the converter, as well as recommendations for determining the basic parameters of electrical equipment.     

Asynchronous electric motors for variable-frequency electric drives of drilling rigs

Operation peculiarities of the main drilling rig mechanisms are considered. The key specification requirements to asynchronous variable-frequency electric motors of the main drives are presented. The possibility of designing and developing the batch production of competitive, domestically produced drilling electric motors at enterprises of RUSELPROM concern is grounded.