Static relays permit enhanced protection

Multi-function multi-phase static overcurrent relays, using digital technology available today, provide basic time, (51) (51G) (51N) and instantaneous (50) (50G) (50N) three phase and ground overcurrent protection, and may offer some or all of the following additional functions: undervoltage (27); overvoltage (59); reverse phase sequence (47); negative phase sequence voltage (47N); directional overcurrent (67) (67N); frequency (81O/U); reverse interlocking trip coil monitoring; and battery monitoring. This article describes two applications that use some of the additional functions in such a relay: reverse interlocking, also using the directional overcurrent (67) function; and ground fault detection for systems utilizing high resistance grounding. The first application was installed on a 4160 volt power system which was supplied by two 5000 kVA transformers     

DRS型发电机低压记忆过流保护装置原理分析与改进

通过对DRS型发电机低压记忆过流保护误动原因的分析,对保护原理提出改进措施,消除了装置的安全隐患。     

DW48-3200/2500型万能断路器自动重合闸功能的探讨

针对万能断路器具有欠电压脱扣的特点,在不改变该产品原设计功能的前提下,通过增加部分控制电路,使断路器欠电压跳闸后,当上级电压恢复正常时,能实现自动重合闸的目的,以此来缩短恢复送电时间,提高供电可靠性.     

基于稀疏矩阵的煤矿电网过流保护检验算法

为了避免矿井高压电网在实际运行过程中可能会出现越级跳闸或保护拒动现象,保证矿井高压电网供电安全,本文基于矿井高压供电网络特点,提出了一种基于稀疏矩阵的矿井高压电网过流保护检验算法,将稀疏矩阵和矿井高压过流保护检验算法相结合,获得支路节点和支路节点的供电关系矩阵,描述了故障电流计算方法,并以此为基础获得了最终需要执行跳闸操作的开关矩阵,对矿井高压供电系统图中相应开关执行跳闸操作。依据开关跳闸结果,即可判断出当前的过流保护设置是否合理。     

Before and during voltage sags

The relationship between the voltages and the tripping level for line-operated synchronous machines is discussed. Voltage sags may cause tripping and large torque peaks in electrical machines. Tripping is caused by undervoltage protection or overcurrent protection. The ability to keep synchronism for the synchronous machines is mostly related to the loading of the machine and not very related to the voltage before and after the voltage sag.     

微机式自适应馈线保护装置

介绍了ＷＸＢ－３２型微机式自适应馈线保护装置的特点、功能,硬软件及使用方法。能在只利用当地故障信息的条件下,在线识别系统的运行方式和故障状态,并在此基础上自动计算整定速断和过电流保护的定值,用户可以根据不同的要求选用不同功能的速断和过电流保护,达到了一机多用的效果;     

发电厂高压厂用分支母线保护优化

长期以来,高压备用变压器、高压厂用变压器低压分支母线通常仅配置复压过流保护,其延时整定为2.0～3.0s。当母线发生严重短路故障时,因复压过流动作时间较长,导致高压备用变压器、高压厂用变压器线圈烧损,影响电厂正常生产。从提高变压器的短路耐受力、装设分支母线差动保护和配置分支限时速断保护3方面的分析表明,增加限时速断保护是最简单有效的方法。首次系统论述了分支限时速断保护的整定计算和灵敏度校验方法,并给出了达拉特电厂高压备用变压器、高压厂用变压器限时速断保护的算例。动模试验和数字仿真试验表明,装设分支限时速断是可行的,目前此方案已经在达拉特电厂完成改造。     

锂离子电池的保护系统

介绍了一种单芯锂离子或锂聚合物电池供电系统的专用保护复合芯片,该芯片集成了保护电路芯片和N沟道MOSFET（Metal Oxide Semicoductor Field Effect Transistor,即：金属氧化物半导体场效应管）开关芯片,从而最大限度地减少了外围元器件需求,降低制造成本并提高产品的可靠性。经测试,其实现了过充电电压、过放电电压的保护,过充电电流、过放电电流的保护,短路保护等各项功能,且工作时功耗非常低。该芯片不仅用于手机设计,也适用于任何需要锂离子或锂聚合物可充电电池长时间供电的各种信息产品的应用场合,有较好的实用价值和推广价值。     

复龙站阀水冷流量保护跳闸隐患分析及处理

阀内水冷系统安全稳定运行对于保证特高压直流输电系统的可靠运行具有重大意义。介绍了复龙换流站验收期间,通过阀内水冷主泵功能试验时发现低流量保护跳闸的重大隐患,分析了保护跳闸的主要原因是:变频器低电压控制功能设置不当、启动备用主泵的时间过长、低流量跳闸二段定值设置过高、站用电400V备自投时间定值设置过长。现场经过优化变频器控制功能、阀内水冷控制系统软件、阀内水冷低流量跳闸二段定值、400V备自投时间定值,有效解决了跳闸隐患,提高了特高压直流输电系统的运行可靠性。     

基于ATmega88单片机的新型电动车控制器的设计

介绍了以ATmega88单片机为控制核心的新型电动车控制器的软硬件实现方案。硬件方面,文中给出了控制器系统总框图并分模块详解了MOSFET驱动、电流检测、语音报警等主要硬件原理图。软件方面,文中画出了系统软件总框图并给出了一种抑制无刷直流电机转矩脉动的软件编程思想。该方案不仅保证了控制器具有传统的电池欠压保护、零启动、过流保护等一系列功能,还使其具有语音报警、自动检相等新型实用功能。经工厂性能测试该控制器取得了理想预期效果并已开始投入实际使用。     

多功能智能型铅酸蓄电池充电器的设计与实现

为了延长铅酸蓄电池的使用寿命,综合各种充电方式的优点,提出了预充、快充、均充和浮充的四阶段充电方法,并运用P89LPC916单片机进行控制,采用了数字滤波PID算法,实现了过压、欠压和过流、欠流保护,过温保护,反接与短路保护,充满电后自动停充的功能     

F35型多功能馈线管理继电器在单母线分段系统中的应用

F35型多功能馈线管理继电器是建立在通用平台上的新一代模块式数字化继电器，用于电气自动化及变电所的保护和控制、测量，以及管理电能质量、数字故障记录及预见性维修。标准应用为多馈线的保护和测量，当有母线电压测量时为5回线路，无母线电压测量时为6回线路。文中介绍如何用F35型多功能馈线管理继电器完成单母线分段系统的进线、母联及电压互感器的全部保护、控制、测量及其他功能。     

A shot in the dark

Investigations of recent blackouts indicate that the root cause of almost all of these major power system disturbances is voltage collapse rather than the underfrequency conditions prevalent in the blackouts of the 1960s and 1970s. The operation of today's power system with generation frequently being remote from the load centers has made the power system very dependent on the utility transmission system. When transmission lines trip, voltage drops at the load center, whereas frequency may remain normal until a complete system collapse occurs. Utilities have begun to recognize this problem and are installing UVLS programs. Also the industrial customers that have in-house generation that operates in parallel with the utility need to recognize the problem. These industrial cogeneration customers should consider the use of undervoltage separation schemes in addition to their existing underfrequency schemes to address the voltage collapse scenario. This article proposes undervoltage separation logic schemes that can be easily installed within digital relays to enhance the security of an undervoltage separation to prevent false operation due to slow-clearing system faults. The article also indicates the required point of installation of these relays so that they properly measure system voltage.     

MMC控制系统中子模块控制器的设计

为了保证模块化多电平变换器(Modular Multilevel Converters,MMC)的正常工作,实现电容电压的平衡控制,设计了MMC控制系统中的子模块控制器。首先阐述了MMC控制系统的总体结构和工作原理,介绍子模块控制器在MMC控制系统中的作用。然后介绍了子模块控制器的主要硬件模块和软件部分的设计,着重介绍了在硬件上实现对IGBT的欠压与过流保护和用软件产生带死区保护的PWM驱动脉冲。最后在基于MMC的直流/交流(DC-AC)变换器实验平台上验证了设计的子模块控制器的合理性和可行性。     

国家风光储示范电站黑启动中风机启动失败原因及对策分析

对风光储电站黑启动的试验过程中风机并网过程进行了分析。首先,重点分析了风机启动造成储能变流器跳闸的原因,并对风机参与黑启动的过程进行了仿真验证,指出由于风机缺少恰当的软启动过程,导致启动过电流,使得黑启动失败;然后,提出了风机参与黑启动过程中直流电压软启动的控制策略;最后,通过仿真对所提控制策略进行了验证,表明所提方法能够很好地避免风机变流器的启动过电流问题。     

IEC61850 standard-based harmonicblocking scheme for power transformers

Transformer Differential and overcurrent schemes are traditionally used as main and backup protection respectively. The differential protection relay (SEL487E) has dedicated harmonic restraint function which blocks the relay tripping during the transformer magnetizing inrush conditions. However, the backup overcurrent relay (SEL751A) applied to the transformer protection does not have harmonic restraint element and trip the overcurrent relay during the inrush conditions. Therefore, major contribution of this research work is the developed harmonic blocking scheme for transformer which uses element (87HB) of the transformer differential relay (SEL487E) to send an IEC61850 GOOSE-based harmonic blocking signal to the backup overcurrent relay (SEL751A) to inhibit from tripping during the transformer magnetizing inrush current conditions. The simulation results proved that IEC61850 standard-based protection scheme is faster than the hardwired signals. Therefore, the speed and reliability of the transformer scheme are improved using the IEC61850 standard-based GOOSE applications.     

西门子7SJ600在天津电网运行中的问题及解决方案

天津电网部分变电站的35kV,10kV线路采用了西门子7SJ600微机线路保护装置。首先．简介了该装置的保护功能、适用性．总结了装置的特点。说明了2座变电站开关越级跳闸的事故情况,分析了西门子7SJ600装置在天津电网运行中2次拒动的原因：1次是线路的过电流时间（1s）与开关速断保护时间（0．7s）不配合,造成相应开关跳闸;另1次是零序电流保护的设定参数错误。针对运行中的问题提出了解决方案：规范了装置参数设置的A,B,C方案,可保证装置的良好运行。     

Development of distributed relaying processor with digitalfiltering of fast sampled data

In order to cope with advanced relaying techniques, a multimicroprocessor-based digital relay was developed. The main features are distributed processing among five processors, 32-b floating-point operations, digital filtering of fast sampled data, and a personal computer based testing tool. Performance tests of this digital relay showed the following characteristics: (1) the error of any relaying element (distance, overcurrent and undervoltage) was less than 1%; (2) operating time was less than 20 ms when the processing interval was 1.67 ms; and (3) a single relaying processor had a computational capacity of six-phase (ground, short×4 steps×3 phases) distance relays based on differential equations, accompanying elements, and a self-diagnosis function in every processing interval     

东莞220 kV立新站和跃立站主变压器跳闸分析

介绍了东莞220kV立新站和跃立站3台主变压器跳闸的情况,对同杆双回线路雷击、故障录波、主变压器中性点保护方式和间隙动作原因进行了详细分析,指出：系统单相接地瞬间产生的暂态过电压作用于主变压器中性点,造成间隙放电,导致过流保护动作,主变压器跳闸。针对主变压器在线路重合前跳闸可能造成停电损失,建议延长间隙过流保护动作时限以躲开线路重合闸,避免主变压器不必要的停止运行。     

火电厂辅机高压变频调速系统的保护配置探讨

从火电厂辅机电动机的保护配置,具体从高压异步电动机的保护配置、电动机保护与高压变频器保护的关系、高压变频调速系统应具有的保护功能(如欠压保护、瞬时停机再启动功能、输入过流保护等)等方面探讨了火电厂辅机高压变频调速系统在保护功能配置方面应该注意的问题,谨供火电厂辅机进行高压变频调速系统的选型和方案确定参考.