Protective system for a high-power capacitor bank

A new protection system for capacitor banks in the case of a short-circuiting accident is described. A pulsed power system composed of many capacitor units and closing switches is well known for producing a controlled pulse current of high power as for the power source of a plasma experimental device, etc. According to the increase of capacity of a bank system, it becomes important to protect the whole bank system from a short-circuiting accident in a capacitor unit. Although some protective ideas have been proposed, these conventional ideas have not been sufficient to absorb the energy flowing into the failure unit from other normal units. Constructing the new 1-MJ capacitor bank for a plasma experimental device, a newly conceived protective device is designed. The new protection system can absorb the bank energy and suppress the short-circuiting current flowing into the failure capacitor units, and overcomes the defect in former protection systems. To confirm the utility of a new protection system, a test of a protection resistor imitating the actual bank circuit was made. The test result showed that absorbable energy for the unit ceramic resistor amounted to 1500 Joule/cc. The new system is adopted to the bank system of the TPE-1RM15 plasma experimental device.     

Bridge capacitor bank design and operation

The concept of a bridge capacitor bank installation was presented in a previous paper (see N.G. Andrei et. al., IEEE Trans. Power Systems, vol.8, no.4, p.1463-70, 1993). This paper discusses design and operation aspects related to the installation of a bridge capacitor bank in a substation. The 138/69 kV bridge capacitor bank installation presented by Andrei et. al. is analyzed. An automatic switching control relay scheme for the same test installation is also discussed. The control scheme takes into account the dual effect a bridge capacitor installation has upon the electrical power system: it generates reactive power on the station 138 kV bus and transfers reactive power from the 69 kV to the 138 kV bus. An unbalance protection scheme preventing the cascading type failure of the capacitor units in the 138/69 kV bridge capacitor bank is also presented. An unbalance protection scheme for high voltage, large MVAr size bridge capacitor banks is also discussed. Simple analytical formulas with practical value to evaluate the magnitude and frequency of the voltage transients generated by the energization of a bridge capacitor bank are presented. Recorded switching transient magnitudes and frequencies are compared with calculated values     

Shunt capacitor bank series group shorting (CAPS) design andapplication

This paper highlights results of a design study to optimize CAPS (capacitor bank series group shorting) as applied to EHV and HV shunt capacitor banks. The study concluded that CAPS can be built from standard, commercially available components, and can have economic advantage over conventional shunt capacitor banks in certain applications. While technically viable, the challenge is finding applications where the benefits are great enough to overcome the reluctance to try something new. Described are application considerations and possible applications evaluated at BPA     

真空断路器投切电容器组试验验证

为寻找真空断路器投切电容器组时发生爆炸的原因，在运行电网上进行了10kV真空断路器投切电容器组的试验，5组样机为不同批号和洁净度的真空灭弧室，将其安装于同一组真空断路器上投切同一组电容器组，通过分析试验结果，得到结论：爆炸原因是真空断路器投切电容器组时发生重击穿并产生较高的过电压；真空灭弧室内部洁净度是影响真空断路器投切电容器组重击穿率的重要因素；真空断路器在投运前进行50次以上的电气老练试验是必要的。     

电容器组不平衡保护动作原因分析

不平衡保护动作是电容器组故障的主要保护,介绍了电容量不平衡保护的方式,分析了不平衡电压的产生原因,总结了不平衡保护的动作原因并实际举例说明,得出了安装质量与实际故障设备对电容器不平衡保护的影响,为电力检修工作人员处理电容器组故障提供了思路。     

电容器组不平衡保护动作原因分析

不平衡保护动作是电容器组故障的主要保护,介绍了电容量不平衡保护的方式,分析了不平衡电压的产生原因,总结了不平衡保护的动作原因并实际举例说明,得出了安装质量与实际故障设备对电容器不平衡保护的影响,为电力检修工作人员处理电容器组故障提供了思路.     

小电流接地系统故障对电容器组零序电压保护的影响

1引言电网中并联补偿电容器组大部分装设在变电站10 kV,35 kV母线上,由于10 kV,35 kV系统中性点一般不接地(或经消弧线圈接地),为小电流接地系统,系统单相接地故障电流很小,两相短路接地时,短路电流较大,入地电流也很小〔1~3〕,显然,零序电流保护不会动作,其零序电压保护是否会     

基于实时预警的火电厂技术监督管理系统

针对目前火电厂技术监督管理信息较为分散,不能及时了解设备运行状态的现状。设计整合所有技术监督信息的技术监督管理系统平台,实现技术监督信息的实时处理与预警。详细介绍系统功能设计、实时数据库设计及系统特色。整个系统采用B/S/D结构,应用Java App let、Java Servlet、COM+、数据库触发器、数据挖掘等技术,实现了技术监督工作的在线实时监督。     

A measurement-based approach for power system instability early warning

Early warning of impending instability in a power system under disturbance conditions is important for preventing of system collapse. A measurement-based approach is proposed to assess the potential power system transient instability problem under cascading outages. Where a measurement-based index is obtained as the estimation accuracy of a linear autoregressive exogenous (ARX) model to estimate the dynamic response of the power system and indicate the system stability to some extent after a disturbance. The proposed approach was verified using a set of marginally stable cases in a 179-bus WECC equivalent power system.     

基于实时预警的火电厂技术监督管理系统

针对目前火电厂技术监督管理信息较为分散,不能及时了解设备运行状态的现状.设计整合所有技术监督信息的技术监督管理系统平台,实现技术监督信息的实时处理与预警.详细介绍系统功能设计、实时数据库设计及系统特色.整个系统采用B/S/D结构,应用Java Applet、Java Servlet、COM+、数据库触发器、数据挖掘等技术,实现了技术监督工作的在线实时监督.     

电网在线可视化预警调度系统

电力系统的运行日趋复杂,原有EMS的数据显示方式已不能满足实际需求。如何生动、明了地显示系统运行信息并予以共享,是电网可视化调度和预警系统要解决的问题。基于IEC 61970标准,提出了在线可视化调度和预警系统的设计方案。介绍了关键技术:可视化方案的确定,SVG图形标准的扩展,不同系统数据的关联和对应以及高效快捷的图形处理。重点阐述了系统设备的静、动态监视的三维展示方法,关键线路低频振荡模式动态阀值,可视化监视以及系统的性能指标。基于所提方案的系统先后在多个实际电网中得到了成功应用。     

Current sharing between diode clamps of polar capacitor bank

The layout of a capacitor bank with clamping diodes is investigated based on an experimental 5.5-kJ energy storage unit for pulsed power applications. While the current sharing between parallel-connected capacitors is good, it is not the case with parallel-connected clamping diodes. Despite a very-low-inductance busbar and attention to symmetrical layout, unequal current sharing results. Good agreement was obtained between measured waveforms and a detailed simulation model. The simulation model indicated that the unequal current sharing is due to small differences between the coupling factors of the parasitic busbar inductances near the capacitors at the ends and at the middle of the bank. It is concluded that the best solution is to place the parallel diodes as close as possible to each other at a position where best averaged coupling is achieved with the individual capacitors of the bank.     

智能电能表故障预警系统的设计与开发

智能电能表因其信息采集的便利性以及功能的完善性而广泛普及,如何高效且有针对性地对数量如此庞大的智能电能表进行维护是电力运营企业面临的挑战.针对此问题,文中提出了基于数据挖掘技术的智能电能表故障预警方法,即利用C 5.0算法构建智能电能表的故障预警模型,通过大量训练集对模型进行训练,再利用测试集计算模型的预警准确度.通过...     

基于预充电的电容器组投切控制策略

为了减小配电网中无功补偿并联电容器组投切时所引起的涌流和过电压,对电容器组的投切过程及其自适应控制进行了研究,提出一种采用普通接触器的投切策略.该策略利用电网特性,通过二极管支路预先使三相电容器中的两相充电,使得一个周期内三相电压波形存在唯一一个同时过零点.在该过零点投入电容器组,能有效降低合闸涌流及过电压.仿真表明,采用该策略投切电容器,电容器合闸涌流被限制在2.5 p.u.以下,电压波形畸变很小.通过添加二极管支路预充电能有效地改善电容器组投切时的暂态性能,从而延长电容器的使用寿命.     

对电容器组串联电抗器的剖析

为了限制电容器组合闸过程中的涌流,限制操作过电压和抑制电网中高次谐波对电容器的影响,在电容器组中加装串联电抗器,会取得满意的效果;通过实例计算说明电容器、电抗器和电容器组的电压和电流的变化情况。     

无功补偿电容器组串联电抗器的参数匹配

串联电抗器是无功补偿电容器中重要的组成部分,串抗率选择不当,可能会使电容器组与系统发生谐振,影响设备的安全和系统的稳定。通过对某一变电站进行电力电容器投切试验和现场测试,得出无功补偿电容器组串联电抗器的参数不匹配是引起该案例中电容器熔丝群爆的直接原因。提出在有限流电抗器的情况下,电容器的设计除了选择合适的串抗率外,还应考虑电容器组等效串抗率,并结合现场实际情况,给出了相应的解决措施。同时分析了电容器组在不同串抗率的情况下,并联补偿支路各次谐波的情况。     

错峰预警信号系统的实现

错峰预警信号系统基于错峰用电方案,通过准确的负荷预测,并将负荷预测结果转化为预警信号,以短信息为通信手段引导客户迅速响应,最终实现有序用电。介绍了广东电网错峰预警系统结构、信号发布流程、畅通系统信道及监督检查方法。     

基于输电线路在线巡视系统的智能预警系统研究

以提高输电线路安全性和可靠性为目的,研究基于输电线路在线巡视系统的智能预警系统的原理。一种新的在线巡视系统采用可视监控、红外成像等技术,通过逐塔配置来替代人工巡视功能,并结合OPGW光电分离和EPON通信新技术实现海量数据的传输,在此基础上构建采用分级结构的智能预警系统。第一级位于杆塔终端主机,通过杆塔就地监测信息对输电线路的故障或异常状态进行初步判断,如利用图像差分等方法;第二级位于后台主机系统,通过系统建模与综合分析精确判断输电线路故障类型,如模糊评判方法。该智能预警系统的运用,可有效实现输电线路及其设备故障异常的智能识别。     

基于嵌入式系统的智慧管廊防灾预警系统设计

智慧管廊是智慧城市的“神经网络”,智慧管廊的安全稳定运营对城市发展、工业生产和居民日常生活有重要的意义.基于嵌入式系统设计了智慧管廊防灾预警系统,选用STM32F107互联型微处理器,实时在线监测管廊内部温度、天然气浓度等环境参数,对电力和燃气管道等重点区域进行全方位的监控,在环境参数超限时进行报警,并启动防灾装置,实现自动防灾预警功能.该系统的运用对保障综合管廊正常运营和居民正常生活具有重要的意义,并且可以与视频监控等系统进行联动,把管廊内部产生的大数据与智慧城市的管理相结合,助力智慧城市的发展.     

基于STM32的地质灾害预警监测系统

针对地质灾害发生后,救灾过程中次生灾害频繁发生的问题,设计实现了基于无线网络技术的在线监测系统.该系统以MSP430为CPU组成监测点,辅以CC2530、ADS1234以及各种传感器,部署于监控区域对雨量、震动、表面位移等信息进行采集、预处理和无线发送等工作;通过基于ARM Cortex-M3的嵌入式系统为控制点与GPRS或卫星连接,将数据处理后传输至控制中心或现场救灾中心;控制中心实现对数据的存储分析并得出预警级别.结果表明,系统实现了稳定可靠的数据传输,运行成本低,报警准确性高,适合监测次生灾害,保障施工区域人员及设备的相对安全.