关于加强电力施工企业内部控制活动的探讨

从施工合同的签订、材料的采购、分包工程的控制、工程工期的控制、废料的回收和工程尾款的回收等施工工程几个阶段的内部控制活动进行阐述,找到加强企业内部管理,提高电力施工企业竞争力的有效途径.     

基于MAS的矿用空压机智能保护系统的研究

分析了矿用空压机传统保护存在的缺陷,结合自适应模糊控制技术,对基于MAS的矿用空压机智能保护系统进行了研究和试验,进一步提高了整个保护系统的准确性和稳定性.重点讨论了空压机排气的卸载压力自适应调整方法.     

环型电网中备用电源自投系统的实现方案

以三亚电网部分110 kV电网为例,在具有多个电源点组成的环型电网中,在没有完善的通讯通道的情况下,提出了切实可行的解决方案。通过备自投系统中各装置相互配合,保证各变电站备自投装置都能可靠正确动作。各装置以采集本地信息为主,根据本地信息判断远方故障及装置的动作情况,而决定本装置应采取的动作措施。针对该电网中存在的大量小电源给备自投的正确动作带来问题,采取相角变化量作为进线电源跳闸的一条辅助判据。     

Iron Loss Characteristics of Electrical Steel Sheet under Inverter Excitation by Power Semiconductor with Extremely Low On‐Voltage Property

In this study, it is demonstrated that the iron loss from the SiC‐MOSFET, which represents a new power semiconductor with an extremely low on‐voltage for electric machine drives, is almost the same as that from an Si‐IGBT, which is a conventional power semiconductor. In order to evaluate the iron loss characteristics when an SiC device is used, two single‐phase pulse width modulation inverters were built and used for the excitation of a ring made up of electrical steel sheet. One of the inverter employed an SiC‐MOSFET, and the other inverter employed an Si‐IGBT. The iron losses for the two inverters are compared.     

ERP在电站设备制造企业物资管理中的运用

ERP（Enterprise Resources Planning）是企业资源计划系统的简称,这种管理系统利用信息技术实现对整个企业资源的一体化管理,是当今国际先进的企业管理模式。ERP系统的重要特点是更加注重于企业供应链（Supply Chain）的管理,而物资管理中的采购管理与库存管理是ERP系统供应链上的核心环节,对保证供应链上物料畅通和实现企业计划的监控与支持起着关键性的作用。因此,电站企业采用ERP系统管理内部资源,优化采购作业,保证生产活动的顺利进行,可使企业最大限度地获得利润,并能提高企业自身的市场竞争力。     

协调可靠性与经济性的园区综合能源系统优化规划

为了确定可靠性与经济性协调的园区综合能源系统规划方案,本文提出了一种由分层经济性优化模型和可靠性校验模型组成的园区综合能源系统优化规划方法。分层经济性优化模型内层以园区年等值费用最小为目标,外层以全寿命周期成本为目标,优化选择设备配置方案;可靠性校验模型对经济优化后的方案进行可靠性校验,分析可靠性提升的边际成本,并提出相应的可靠性提升措施,反馈至经济性优化模型并给出改进方案。通过对优化模型和校验模型的循环迭代,得到可靠经济的园区综合能源系统规划方案。最后,以江苏某综合能源系统园区为实例,给出了其规划方案,验证了所提方法的有效性。     

基于INT51X1芯片的调制技术在10kV配电网自动化通信系统中的应用

在10kV电力线上实现高速数据传输有着广阔的应用前景和经济价值，但是由于电力线信道存在着不可预期的高噪声、多径效应和信道衰落，严重制约了高速数据的传输。而近几年兴起的无线信道上实现高速数据传输的新技术，即OFDM(多载波正交频分复用)技术，是解决这些电力线通信问题的有效方法，文中提出了一种基于美国Intellon公司的INT51X1电力通信专用芯片并结合台湾Winbond公司32位ARM7TDMI内核的RISC微处理器W90N740的PLC通信系统的设计。     

基于红外半球摄影的无线叶面积指数传感器设计

叶面积指数（leaf area index, LAI)是研究林地生态系统和植被冠层结构的重要参量,高效、准确地测量LAI是森林资源清查工程中的一项重要工作。传统的LAI测量方式需要人工手持仪器至现场测量,费时费力,近年来随着物联网技术的发展,利用无线传感节点测量LAI的技术逐渐走向成熟,但仍有部分问题亟需解决。本文提出了一种基于红外半球摄影（digital infrared hemispherical photography, DIHP）的LAI测量方法,设计了针对红外摄影颜色空间的自适应分割算法,并部署在边缘计算平台“树莓派”上,解决了传统半球摄影法（digital hemispherical photography, DHP）容易受环境干扰的问题。所设计的传感节点测量值与手持式植被冠层分析仪HM-G20比较相关性显著,R值达到了0.99691,平均测量准确度可达93.57%,比DHP方式提高了13.85%。该DIHP节点运行功耗较低,满足林业物联网长期实地部署的要求,具有极大的应用前景。     

A Mixed-Mode Analogue and Switch Level Simulator

This paper describes an experimental mixed-mode simulation system which couples an incremental time analogue simulator to an event-driven switch level simulator. the analogue timing programme uses a variable-step-size, multi-order (VSMO) numerical integration algorithm which detects and uses latency while maintaining wave-form synchronization. the switch level programme uses piecewise linear wave-forms rather than discrete states to model the operation of logical networks. A unified format in which time responses are events is used for communication between the two programmes. the mixed-mode simulator operates without backtracking or translation between logical states and analogue wave-forms.     

铝电解供电整流柜专业点检流程

供电整流柜是铝电解生产的重要设备,它承担着整流和电能传输,是提供直流电能的必要设备;对铝电解平稳生产起着非常重要的作用。因此,将专业点检纳入到企业设备管理之中,借助专业工器具,按照预设周期和科学方法,对设备上的规定部位进行预防性周密检查。通过对设备的专业定期检查,收集数据,进行分析;从而对设备存在的问题进行推理判断、技术诊断等,能够及时发现设备潜在的故障倾向状态。但目前来说,铝电解供电整流柜的专业点检,并没有统一的标准,本文结合作者专业点检经验,阐述铝电解整流柜专业点检工作相关流程及工作思路。     

BTG项目中的厂用电量计算方法分析

火力发电厂设计中,厂用电量是反映电厂工艺流程设置和设备选择是否合理,评价工程设计质量的重要依据。总包合同把厂用电量设定为性能保证参数,同时规定了严格的考核约定。通过对海外市场BTG项目影响厂用电量的因素进行研究和分析,提出一种相对比较切合实际的厂用电量计算方法,以提高工程性能保证值的可靠性,降低工程风险。     

Equivalent turbogenerator model for design of multivariable controllers in multimachine systems

The design of multivariable controllers for turbogenerators is usually based on single-machine infinite-bus representations, which are not valid for multimachine power systems. Alternatively, an overall control strategy may be sought for all the generators in the system, but this arrangement is not feasible in practice and involves major mathematical difficulties. The paper describes a method for designing physically-realizable multivariable controllers for individual turbogenerators in multimachine systems, without the assumption of an infinite bus. This employs an equivalent model for each generator, which includes the effects of interconnections with other units in the power system. The method has been used to design optimal state-space controllers for a three-machine system, and results obtained by nonlinear computer simulation show that good performance is achieved.     

Product liability and malpractice

The expanded definition of liability, which includes the liability of those who design, manufacture, and sell products, is discussed. Also examined is malpractice, in which the engineer may be subjected to liability on an individual basis. It is noted that liability under both products liability and malpractice doctrines has also expanded beyond the physical limits of the state in which the corporate principal place of business is located to encompass any state in which a company sells products, not just that in which an engineer is employed. The significance of these developments for the individual engineer is examined     

Method of detecting the index position of a spindle motor for slim flexible disk drive

A slim flexible disk drive, which could be mounted on a hand-held personal computer, is now under intensive study in Japan. The spindle motor for the flexible disk drive has an index-position detecting means, an index magnet attached to the outer wall of the periphery of the rotor yoke, and a magnetic sensor which detects the magnetic flux from the index magnet. As a result, spaces for providing the index magnet and the magnetic sensor prevent the motor from being made smaller in size and reduced in thickness. This paper describes the method for detecting the index position of a spindle motor without both the index magnet and the magnetic sensor. This method detects an index position per rotation from two different kinds of frequency generating signals (main FG and sub FG) through an index-detecting circuit. The thin spindle motor to which this index-detecting method is applied, performed a smaller degree of rotational speed variation compared with another well-known one without both the index magnet and the magnetic sensor. This index-detecting method is most suitable for a less-inertia-thin spindle motor, and is easy to assemble.     

Available transmission capacity (ATC) and its value under openaccess

Strictly engineering aspects of available transmission capacity (ATC) are analyzed first. Nonlinear network theory is used to provide several key conditions under which one could define a notion of ATC and specific novel algorithms for its evaluation. Next, the fundamental problem which prevents one from developing an economically efficient distributed transmission market based on the ATC is identified. It is suggested that for an electric power network of an arbitrary topology it is not possible to map the computed ATC onto its market value. All findings are illustrated using examples of small power systems     

Valuation of harmonic injection costs

Proper valuation of harmonic injections and distortion is critical if an efficient solution is to be provided for any harmonic problem, which may exist. Indeed without proper tools to value harmonic distortion, it is not possible to quantify the extent of any problem. This paper demonstrates that is possible to develop marginal prices for harmonic injections, which will accurately reflect the value of the injections to the rest of the network. Given an allocation of harmonic pollution rights these prices act to coordinate each member of the network to act in a globally optimal manner.     

Heat Pump Water Heater Control

A control system is described for a heat pump water heater which uses the thermostat on an existing electric water heater to determine the need for water heating. The control system allows an installer to wire in an electric water heater with the heat pump using the same connections for supplying power to the water heater which would normally be used. This control system will also automatically turn off the heat pump when frost forms on the evaporator coil and will allow the electric elements in the tank to heat the water. The system is easy to install, provides reliable operation of a heat pump, does not create any unusual safety problems, and gives uninterrupted hot water service.     

A Bit-Slice Microprocessor System for Teaching Microprogramming

This paper describes a microprocessor development system, which was designed for demonstrating the use of bit-slice microprocessors, for teaching microprogramming and for simulating other small microprocessors. The system contains two 2901 bit-slice microprocessors together with the necessary control and sequencing logic, a 256 × 56 bit microprogram control memory, a macromemory with associated address and interface registers, and an interface to an MDS-80 microcomputer development system. A monitor program which runs on the MDS-80 controls the execution of the 2901 microprograms. This monitor provides for loading microprograms, examining and changing both the microprogram and macroprogram memory, examining and changing 2901 internal registers, setting breakpoints, and tracing microprogram execution. The monitor also provides an interactive editor for altering microprograms. A cross-assembler for the 2901 microcode was also developed. This cross-assembler accepts inputs in a register-transfer format and generates the 56-bit wide microcode words ready for loading into the 2901 control memory. Student projects which have been completed using the system range in difficulty from a binary multiplier to an emulator for the M6800 microprocessor instruction set. The system is easy to use, is relatively low in cost, and has proven to be a valuable educational tool.     

Recursive blind image deconvolution via dispersion minimization

This paper presents an adaptive autoregressive (AR) approach to the blind image deconvolution problem which has several advantages over standard adaptive FIR filters. There is no need to figure out the optimum filter support when using an AR deconvolution filter because it is the same as the support of the blur. Thus there is no distortion introduced by the finite support of the FIR filter. While an FIR filter provides an approximate inverse to the blur at convergence, the AR filter converges to an approximation of the blur itself. Hence, the method can be used for blur identification. Simulations suggest that convergence of the adaptive AR filter coefficients occur rapidly and the improvement in signal‐to‐noise ratios are higher than in the FIR case for a given blur (and with the same step‐size for the adaptive algorithms). When the adaptive AR method is derived naively to minimize the dispersion, it requires a recursion within a recursion which is computationally complex. We propose a simplification that removes the inner recursion, and prove conditions under which this simplification is valid when dealing with binary images. Simulations are used to show that the method may also be applied to certain multi‐valued images as well. Copyright © 2005 John Wiley & Sons, Ltd.