库车火电厂2号给水泵二次事故分析

1事故概述2006年10月26日,库车火电厂2号给水泵启动时发生事故。事故过程如下:在给水泵启动10秒内,电机内部发出极大的噪声,凌晨0点整,给水泵顺启失败,速断保护动作,伴随着"铛"的一声巨响,电机内有火花冒出,并有焦糊味散出,DCS显示,整个启动过程,给水泵电机转速为0转,未发生变化,现场解体检查发现:电机定子绕组三相短路,其中B相、C相绕组匝间短路,且线圈对地绝缘击穿。     

开断感应电动机过电压事故分析

用少油断路器投切感应电动机的事故时有发生,如辽宁、山东及安徽等地用SN_(10)—10型断路器开断6kV 4000kW启动状态给水泵电机时,曾先后发生断路器自爆喷油着火,甚至造成发电机仃机的严重事故。1982年我省戚墅堰电厂在启动2000kW给水泵电机时,又发生一次过电压事故,但这次事故和通常情况不同,操作断路器和给水泵电机本身均完好无损,远离操作断路器40多米电缆处的发电机侧的厂用开关却发生了对地闪络并发展到三相短路,以致使一台发电机仃机解列。     

330MW机组给水泵变频改造

介绍大唐桂冠合山发电有限公司330MW火电机组给水系统给水泵变频改造情况,阐述改造后初次投运方案以及对给水泵系统控制逻辑的调整.改造后,给水泵电机噪音降低,电机启动电流冲击减少,且节能效果明显.     

给水泵电机启动时差动保护误动原因分析及处理

针对某电厂给水泵电机在启动过程中因电流互感器饱和造成差动保护误动事件进行了原因分析，从录波图中给水泵电机启动时引起电流互感器饱和的不同时刻直流分量进行了分析，得到了差动保护误动的原因，对二次回路、保护定值、软件程序、采样板硬件进行了优化，保证了给水泵电机能够正常启动，机组设备稳定运行。     

电动给水泵电机端部线圈故障分析与处理

介绍了某发电公司1,3号电动给水泵电机启动时发生的绝缘故障,以及2,4号电动给水泵电机端部线圈缺陷的情况,分析了电机绝缘故障及缺陷产生的原因为真空开关操作过电压、启动电流冲击、绕组绑扎工艺不良,并对1,3号电动给水泵电机绕组短路故障的具体原因进行了分析,最后提出了针对性的解决措施。     

中压电机启动引发辅变开关柜综合报警故障分析

在核电厂厂用电机负荷中,有不少大功率电机,如主冷却剂泵、电动给水泵、循环水泵等,额定功率均超过5000 W,这些大电机在启动时有可能导致其所在6 kV厂用电母线电压明显降低。通过对电动给水泵电机启动引发辅变开关柜综合报警故障的分析,阐述大电机启动对母线电压的影响,为相关技术人员提供了类似故障的分析方法和处理经验。     

LDQ系列高压鼠笼电机液体电机启动器的应用

通过在高压给水泵电机上安装LDQ系列高压鼠笼电机液体电机启动器,减小电机瞬间启动电流,保护了高压电机,延长了设备运行周期。     

全变频中压给水泵意外跳闸原因分析及改进

某发电厂锅炉房内使用2台中压给水泵给1台锅炉补水,电机采用变频器控制,但在某次日常维护中误碰非关键按钮导致设备意外跳闸,给整个锅炉系统的运行带来了极大的安全隐患.通过分析及优化变频回路,实现在不改变原有启动和运行模式的情况下,确保所有非关键按钮无法影响给水泵电机的正常运行.     

一起给水泵差动保护动作事故的原因分析

介绍了一起发电机组C给水泵差动保护动作事故。通过试验分析,确认引起故障的直接原因是:C号给水泵电机中性点C相电流回路的压板退出不完全造成差动电流回路分流,继而引发差动保护动作,提出了相应的改造措施和技术规范,以避免事故的再次发生。     

给水泵电机频繁烧毁原因分析及防范措施

简要分析了给水泵电机自投运以来频繁烧毁的原因 ,提出了电机防烧措施 ,对预防电机频繁烧毁事故的发生可起到指导作用。     

A generalized approach for the steady-state analysis of resonantinverters

A generalized approach is presented for the steady-state analysis of resonant inverters which leads to the selection of an optimum scheme for a particular application. Six load-commutation schemes are combined into a single commutation scheme, referred to as a generalized load-commutation circuit, and the steady-state analysis for the circuit with RL load is presented using a Fourier series approach in the continuous-current mode. The equations for different load-commutation circuits are obtained as the particular cases of the generalized configuration. This type of unified approach simplifies the method of analysis for different commutation schemes and eliminates the need for the separate analysis of different schemes. Also, in a computer program, the results for a particular configuration can be obtained simply by opening or shorting the nonrequired commutating components of the generalized scheme. The method of analysis is used to select resonant inverter schemes with resistive load, based on certain constraints. Experimental results are presented for the selected schemes to support the theory     

Emphasizing formal analysis in a software engineering curriculum

The integration of formal method application throughout a six course software engineering curriculum is outlined. Formal analysis skills were included in order to increase the complex program solving skills of the student. The five instruction-oriented courses presented highlight how formal analysis was introduced in and applied to the corresponding subject material. The materials presented, along with an accounting of the experiment, provide a basis for other academicians to teach formal analysis at their own institutions.     

Design, fabrication, back-to-back test of 14200-hp two-polecylindrical-rotor synchronous motor for ASD application

This paper describes the design aspects, fabrication, and testing of a 14200-hp two-pole cylindrical-rotor synchronous motor used with a load-commutated inverter (LCI) adjustable-speed drive (ASD) to drive a refrigeration compressor for a refinery alkylation plant. The motor design aspects include extensive finite-difference analysis of the rotor cage assembly and laboratory bench testing of a wedge assembly to verify finite-difference analysis results prior to fabrication. Torsional and harmonic analysis results are also presented. Special considerations are discussed regarding rotor heating due to harmonic currents and mitigation methods for handling the harmonic currents and heating. Mechanical design aspects are presented of the rotor cage, including rotor slot design, wedge, and end ring assembly. Two motors and drives were built, for companion projects, allowing for verification of the rotor-cage assembly by a back-to-back (BTB) test. Test preparation, setup and results are presented, including rotor temperature mapping, vibration data and torsional results. Finally, test results are compared with calculated values     

Instrumentation of a NASAP Subroutine

A program for the detection of loops in a circuit analysis is presented. This program, a FORTRAN routine entitled LOOPS, is the heart of the UCLA version of NASAP (Network Analysis for Systems Applications Program). In order to study the execution of LOOPS, it has been subjected to an automatic instrumentation process developed at UCLA. Results of this analysis are presented showing the most time-consuming portions of the routine and other performance measurements.     

1 000 MW汽轮发电机端部磁-热耦合分析

基于有限元方法，对1 000 MW汽轮发电机端部行波电磁场和三维温度场进行了时谐耦合场分析。在发电机额定短路运行工况下，端部结构件的耦合场数值分析计算结果和相应温度实测数据间的误差满足工程分析精度要求，表明构造的时谐耦合场计算模型和分析方法的正确、有效性；并给出了空载、额定负载和进相0.95等运行工况下结构件的涡流损耗及其温度分布。该文采用的方法可用来指导电机的稳定安全运行，并为预测汽轮发电机的进相运行能力提供了可靠的理论分析基础。     

研究大规模互联电网区域间振荡的特征值分析方法

分析了小干扰稳定性分析方法的现状及存在的问题,介绍了大型电力系统分析软件NETOMAC所特有的特征值分析程序NEVA中适用于大规模互联电网小干扰稳定性分析的特征值算法.该程序及其算法具有极强的实用性,为互联电网的区域间振荡分析及阻尼控制研究提供了一种应用级的有效手段.最后以跨欧洲互联电网为例进行研究,说明了所介绍程序和算法的强大分析能力.     

A simple introduction to finite element analysis of electromagneticproblems

An elementary tutorial introduction in finite-element numerical analysis is presented. The finite-element method is applied to Laplacian electrostatic field problems. Suggestions are offered on how the basic concepts developed can be extended to finite-element analysis of problems involving Poisson's or the wave equation. A step-by-step procedure for coding the numerical method is presented; a useful, working FORTRAN program is also included     

Blind adaptation of decision feedback equalizers: Gross convergence properties

An analysis of the stochastic dynamics of the blind adaptation of decision feedback equalizers is presented. The analysis accounts for the presence of decision errors which, under feedback, are propagated. A number of blind algorithms are presented and a theory is developed to explain gross convergence properties observed through simulations. The possibility of and mechanism behind undesirable local minima are highlighted and a detailed case study is given. The potential capture by local minima shows the importance of good initialization. These results superficially resemble those obtained for blind adaptation applied to linear equalizers.     

利用六序分量复合序网法分析同杆双回线故障的新方法

本文结合同杆双回线的特点,引入六序故障分量,推导出同杆双回线120种故障的六序故障分量解析计算式,由此提出了六序复合序网分析同杆双回线故障的新方法,此方法在计算同杆双回线故障时非常简单,并且六序故障分量之间的相位关系和幅值关系可在复合序网中很直观地表现出来.通过EMTP仿真计算证明了本文所提方法的正确性.     

时间同步监测分析系统的开发与应用

介绍了时间同步监测分析系统的设计和实现.提出了基于实时监测层、实时分析层和综合应用层3层架构的时间同步监测分析技术框架,讨论了时间偏差抑制、时间一致性分析、自守时精度分析、误差综合诊断、网络时间协议(NTP)时间戳性能监测等关键技术.介绍了系统的工程实现,探讨了时钟状态分析、时间误差诊断和系统性能分析等系统应用.