发电机励磁系统失磁及案例分析

本文通过介绍发电机励磁系统,分析发电机的失磁原因,发电机失磁对电力系统产生的危害,分析了发电机失磁保护容易误动的原因,最后解析了一个发电机失磁事故,并提出了相关预防措施。     

自并励励磁发电机对继电保护的影响

针对自并励励磁发电机与传统励磁同步发电机在励磁方式上的不同,分析了电力系统发生短路时发电机对系统及继电保护的影响。     

由于电流采样错误导致的停机事故分析

本文主要分析了一起由于电流采样错误导致的停机事故,并根据该事故提出整改措施,防止类似事故发生。     

电厂发电机定子接地故障原因分析与处理

介绍发电机定子线圈发生接地故障的情况,以及查找故障点的方法。对故障原因进行了分析,判定以往事故冲击和线棒局部放电是本次事故的主要原因,并提出了防范措施。     

汽轮发电机组励磁稳定性分析

对该厂一起汽轮发电梵失磁而引起全厂跳车事故进行了分析,并提出了汤轮发电机失磁的危害。     

6MW发电机逆功率运行分析及技术改造

针对云南天安化工有限公司一期800 kt/a硫酸装置配套的6 MW中压发电机组在运行过程出现逆功率运行的不正常运行现象,阐述了发电机逆功率运行的现象和实际危害.通过理论分析,提出了切实可行的技术改造方案,完善了发电机的主保护,从本质上避免发电机出现逆功率运行,减少设备损坏事故的发生,保证电网的安全运行.     

膨胀发电机试车损坏原因分析及预防措施

分析膨胀发电机在试车过程中发生部件损坏的原因,提出合理的预防措施,并试车成功,从而杜绝了此类事故的发生。     

发电机欠励运行的危害

由于励磁回路的部件及自动励磁调节装置发生故障或由于系统事故造成发电机欠励运行,严重时将破坏电力系统的稳定运行,威胁发电机的自身安全。为限制发电机的进相无功不超过允许范围需装设欠励限制器以限制励磁电流的减少。     

300MW汽轮发电机组闭式循环冷却水系统的优化改造

内蒙古能源金山热电厂汽轮发电机组氢气冷却器冷却水由闭式循环冷却水提供,原设计安装不能满足发电机在额定氢压（0.25 MPa）与低氢压（氢压为0.05MPa）运行时的要求（任何时候氢冷器冷却水压力都应小于氢压）,这样如发生氢冷器泄漏,会造成发电机内进水,发电机损坏事故。通过分析论证,采取了降低闭冷水箱安装高度的优化改造,降低了氢冷器冷却水压力,满足发电机低氢压运行的条件。     

浅谈发电机-电动机直流调速系统正负反馈检测方法

我公司采矿场配备三台WK-4A型电铲,由6kV移动电缆供电.该电铲系发电机一电动机直流调速系统,三台发电机由一台6kV交流电动机牵引,磁性触发器、可控硅控制调速.     

基于西门子7SJ62的变压器励磁涌流抑制保护

分析基于西门子7SJ62综合保护装置的变压器励磁涌流抑制的原理和对变压器在合闸过程瞬间产生的谐波分量,以及如何利用7SJ62综合保护装置的交叉闭锁功能检测二次谐波电流的涌流,并利用软件实现对涌流的抑制保护功能。     

电动机低电压保护误动作分析及处理

介绍电动机低电压保护的原理,针对DMP371微机电动机保护测控装置低电压保护误动作原因进行分析,采取改写DMP371微机电动机保护测控装置程序,解决低电压误动作的问题。     

Flexible Nanocomposite Generator Using PZT Nanorods and Ag Nanowires

This study presents a piezoelectric composite generator using PDMS polymer, PZT nanorods, and Ag nanowires. To enhance output power of the generator, we inserted the Ag NWs into the PDMS‐PZT composite, which play very important roles in our generator: First, it enables the PZT NRs well distributed in PDMS polymer. Second, it is to reinforce the applied stress of the device by enhancing its flexibility. Finally, conduction paths formed by the Ag networks can reduce the internal resistance of the device. To assess these effects, we have compared and evaluated output voltage and current of four different generators.     

捞渣机链条张紧装置改造

为消除GBLl2AX26型捞渣机刮板及链条磨损严重、张紧架刚性不足变形、断链检测不精确、保护存在死区等问题,将捞渣机张紧装置改造为单向机械逆止机构的液压自动张紧装置,断链检测改为2个检测点,分别检测2个张紧轮。改造后捞渣机2根链条张紧力平衡恒定,刮板与底板摩擦阻力很小,断链保护装置动作灵敏可靠,确保了发电机组长周期经济稳定运行。     

Electrochemical generators of pulsating or alternating current

This paper concerns the design of three different electrochemical generators of nonsteady current: two generate a pulsating direct current, the third generates an irregular alternating current. The (Fe|NaBrO3(aq.)+H2SO4(aq.)|Pt) generator induces an alternating current in a secondary circuit connected to a transformer. The influence of electrode size and external resistance on current oscillation parameters and on power is shown. The shape of current oscillation in the generators (Fe|NaBrO3(aq.)+H2SO4(aq.)|Pt), (Zn/ZnSO4(aq.)||NaBrO3(aq.)+H2SO4(aq.)|Fe) and (Fe|NaBrO3(aq.) +H2SO4(aq.)|Fe) are also shown and the working of the three generators is explained.     

微机保护装置使用经验点滴

保护装置微机化是科技发展的必然,微机保护逐步成为保护装置的主流。定值整定、保护及二次回路接线、设备配合直接影响到装置的应用效果和被保护对象的安全运行。     

硫酸装置余热发电电气设计要点

硫酸装置余热发电机的安全运行对保证电力系统的正常工作和电能质量起着决定性作用,同时可提高硫酸装置生产的供电可靠性和经济效益。着重介绍了余热发电的发电机一次接线系统、二次回路、保护设置、同期点和解列点设置及同期装置的选择等设计要点,指出电气设计中需注意的几个问题。     

RESINE有源滤波装置在海油平台变频供电系统中的应用

文章介绍一个RESINE有源滤波装置在海油平台变频供电系统中的应用案例,并对滤波装置投运前后的主要参数进行了分析对比。实际运行效果显示,RESINE有源滤波装置可明显改善变压器负载侧电流波形,降低电压和电流畸变率,提高系统的功率因数,提升变压器或发电机的带负载能力。     

Forming-free,ultra-high on-state current,and self-compliance selector based on titanium-doped NbOx thin films

NbO₂-based selectors can effectively suppress cross-talk interference between memory cells in the high-density cross-point nonvolatile memory arrays. By doping titanium into the niobium oxide, the Pt/Ti:NbO_x/TiN selector device based on insulator–metal transition (IMT) effect presented typical threshold switching (TS) behavior. Compared with the undoped device (UD), the doped device (DD) performed forming-free, ultra-high on-state current and self-compliance properties. Meanwhile, its performances were stable in 1000 consecutive cycles of TS. Subsequently, the mechanism of the device was understood based on oxygen vacancies adjusted by Ti atom. This device provided an approach to drive memory for V-point structure due to the ultra-high on-state current.     

Characterization of leakage current on diamond Schottky barrier diodes using thermionic-field emission modeling

A diamond vertical Schottky barrier diode (SBD) with nonepitaxial crystallites (NCs) exhibits high leakage current in both its forward and its reverse characteristics. A shunt path current through the grain boundary of the NCs is the dominant mechanism. The defectless device shows a low leakage current of less than 10^− 11 A/cm², and the device yield corresponds to the density of the NCs. The reverse leakage current of the defectless device increases with the reverse field. The leakage current of the diamond SBD is in good agreement with the tunneling model described by thermionic-field emission (TFE) rather than the conventionally used barrier-lowering model. The TFE current dominates when the reverse electric field is larger than 1.2 MV/cm, and current density reaches 10^− 6 A/cm², even at 1.6 MV/cm, which is lower than the avalanche limit.