真空断路器电磁瞬态仿真模型的研究与应用

由于真空断路器具有优良的开断和绝缘恢复性能，因此，可用来开断由于电弧不稳定而产生的高频电流。在一定的电网奈件下，在开断高频电流的过程中可能引起多次重燃和严重的过电压。本文的主要目的是用PSCAD建立真空断路器模型来展现断路器的真实特性。这个模型融合了燃弧时间、截流，介质恢复强度及断路器的熄弧能力等所有本质特性。采用开断实用的电炉用变压器来检验本文所开发的三相真空断路器的模型。并提供了检验结果。     

Clearing faults near shunt capacitor banks

Fault interrupting tests on high-voltage circuit breakers confirmed the problems of breaking a short-circuit current, which can occur in substations with shunt capacitor banks. Research was conducted on the behavior of different extinguishing media. Tests show that all types of circuit breakers (including the restrike-free breakers) have reignitions after the interruption of faults in the vicinity of a shunt capacitor bank. This is caused by the low rate of rise of the recovery voltage which gives the circuit breaker an opportunity to clear at short arcing times. Reignitions occur because of the low dielectric withstand capability of the small contact gap. Both tests and computer calculations show high overvoltages when the circuit breaker interrupts at one of the superimposed high-frequency current zeros which are created after reignition. Some breakers interrupt at a high-frequency current zero and thus create overvoltages. Other breakers do not interrupt at a high-frequency current zero and wait for a current zero of the power-frequency current, thus prolonging the arcing time. The overvoltages in three-phase circuits are higher than in single-phase circuits     

Extending the Application Field of Vacuum Circuit Breakers to Generators for Capacities up to 400 MW

The progress that has been achieved in the development and manufacture of vacuum circuit breakers opens the possibility of using them for a wider range of applications at power plants, including as generator circuit breakers. Such characteristics of modern vacuum circuit breakers as increased breaking capacity and high switching life are factors that make them closer in competitiveness to SF6 circuit breakers for generators with capacities up to 400 MW. The article considers problem aspects relating to clearing of short-circuit faults in the generator voltage circuits and interruption of out-of-phase making currents and no-load currents of generator transformers. Conditions leading to a longer period of time to the moment at which the switched current crosses zero are considered. It is pointed out that, unlike the IEC/IEEE Standard 62271-37-013, GOST (State Standard) R 52565-2006 does not specify the requirements for generator circuit breakers in full. The article gives the voltage drop values across the arc for different design versions of vacuum circuit breaker contacts and shows the effect the arc in a vacuum circuit breaker has on the time delay to the moment at which the current crosses zero. The standardized parameters of transient recovery voltage across the generator circuit breaker contacts are estimated along with the contact gap electric strength recovery rates ensured by modern arc quenching chambers. The switching overvoltages arising when vacuum circuit breakers interrupt short-circuit currents and no-load currents of generator transformers are analyzed. The article considers the most probable factors causing the occurrence of switching overvoltages, including current chopping, repeated breakdowns of the circuit breaker contact gap, and virtual current chopping. It is found that, unlike repeated breakdowns and virtual current chopping, an actual current chopping does not give rise to dangerous switching overvoltages. The article also determines the vacuum circuit breaker application field boundaries in which dangerous switching overvoltages may occur that would require additional measures for limiting them.     

应用相控合闸技术抑制并联补偿线路断路器直流偏置问题的研究

笔者对带有并联电抗器的线路,合空线操作时流过断路器电流的直流偏置问题进行了分析。在对直流偏置产生的原理、影响因素及可能引发故障风险的工况进行分析的基础上,对控制合闸相位、降低补偿度以及加装合闸电阻等抑制直流偏置的措施进行了比较。并进一步对应用合闸相位控制技术抑制直流偏置的相关技术进行了研究,包括控制策略、反馈参数以及对操作过电压的影响等方面。在此基础上针对典型线路对相控合闸技术的应用效果进行了实测,证明了限制效果的有效性,并对其适用范围进行了分析。     

特高压交流输电系统短路电流零点漂移影响因素分析及防治措施

在特高压输电系统中,当线路发生故障时,断路器动作会产生较高的瞬态过电压,其中直流分量部分可能会使故障电流出现零点漂移现象,使断路器灭弧室内燃弧时间延长,影响断路器的开断能力。为此,首先结合特高压示范工程,对影响零点漂移的因素进行了理论分析,并根据浙江北—上海西特高压输电线路,考虑断路器断开时的电弧模型,利用ATP/EMTP进行了仿真计算,得出:影响特高压零点漂移的因素有故障发生时刻、故障点的接地电阻大小、故障点的位置,以及负载电流的大小,其中负载电流的变化可能会引起长达2个周波以上较严重的零点漂移。最后总结出断路器串联50Ω的合闸电阻可有效减小短路电流首次过零时间。     

基于线圈电流和触点状态的断路器故障分析

介绍了一种基于线圈电流信号与触点状态的高压断路器故障诊断专家系统。首先,分析了高压断路器的操作过程,并根据其操作特性提取隐含在线圈电流和触点状态中的有效信息;其后,在找出特征参数与断路器状态对应关系的基础上,设计了基于规则的断路器故障诊断专家系统;最后,以锁勾润滑不足、分闸线圈故障2种故障为实例,分析专家系统的推理过程。经试验验证,该专家系统可以准确地诊断出断路器多种故障,并在目前断路器维护现状的基础上给出合理的检修建议。     

智能相控断路器在35kV并联电容器投切中的应用

某500 kV变电站利用SF 6断路器投切35 kV并联电容器组时,连续发生2起串联电抗器设备故障,分析原因是在投切操作过程产生了较大的涌流及过电压,引起干式空心电抗器发生匝间短路故障,严重威胁系统的安全运行。为了避免此类故障的再次发生,提出采用适用于投切35 kV并联电容器组的智能相控断路器来抑制合闸涌流,降低分闸重燃概率。为验证智能相控断路器的有效性,首先分析了投切涌流及过电压产生的原因和相控开关技术的原理,然后将智能相控断路器应用于该500 kV变电站的35 kV无功补偿系统,并分别对智能断路器与普通断路器进行多次分合闸对比试验,试验结果表明:普通断路器随机投切电容器组产生的最大涌流为4.2(标幺值,下同),过电压为1.81;智能相控断路器投切电容器组产生的最大涌流为2.3,过电压为1.4。试验结果证实智能相控断路器的应用能够从源头抑制合闸涌流和过电压,提高无功投切效率和系统安全性。     

Hydro-Quebec's concerns related to performances of SF6circuit-breakers

Hydro-Quebec's concerns regarding circuit breaker reliability are presented. Emphasis is placed on two aspects crucial in determining line charging current breaking capacity, i.e., the arc duration and the test circuit configuration. The importance of manufacturing quality for the arcing contacts, nozzles and gasket is discussed. Test criteria at 20°C for simulating breaking tests at -50°C are given. Hydro-Quebec's requirements for testing the tightness of SF₆ breakers are presented together with a reliable leakage-measuring method     

Total Motor Branch Circuit Protection with Instantaneous Trip Type Circuit Breakers and High Fault Circuit Protectors (HFCP)

Instantaneous trip type circuit breakers can protect controllers against damage due to overcurrents above six and up to 13 times full load motor currents (FLMC). They may be used for full protection if the starter and wire are self-protected up to 13 times FLMC. Molded case circuit breakers take at least 1/2 to 1 cycle to interrupt. An interrupting time of 1 cycle is too long at high let-through currents to protect contactors from being damaged and, in many cases, to protect heaters from being burned out. A line of high fault circuit protectors is described that protect all branch circuit components in case the available short circuit current is so high that the let-through current would, without protectors, be higher than a current that the branch circuit elements could with-stand for at least 1 cycle. A system is described that insures tripping of the circuit breaker whenever a high fault circuit protector opens. Tests, physical arrangements, coordinated system selections, and applications are described.     

电抗耦合与不同期合闸对10kV并联电容器组合闸暂态的影响分析

重庆市电力公司变电站近年来多次出现10 kV系统并联补偿电容器组合装置合闸过程中断路器(柜)故障事件.笔者从实际安装运行条件对合闸的过渡过程进行深入的理论分析:建立了1个含耦合电感的三相二阶电路模型,对该电路进行等效解耦和Laplace变换及反变换,分析了电感之间存在不对称耦合电感对三相电路过渡过程的影响;建立了含对地...     

±800kV侨乡换流站500kV交流滤波器小组断路器选相合闸问题分析

±800 k V侨乡换流站500 k V交流滤波器562、583小组断路器选相合闸功能投入后,出现无法在电压过零点进行准确合闸的问题。通过分析断路器选相合闸装置的功能原理和实际配置,进行了断路器机械性能和带电分合等试验,认为选相合闸装置的电气合闸时间要短于机械合闸时间,选相合闸的定值整定应适当考虑预击穿时间,必须对断路器的机械特性、预击穿特性进行试验验证,才可以确定正确定值序列,同时保留合理裕度。在合理设置选相合闸控制定值后,最终实现交流滤波器在电压过零点准确合闸。     

10kV开关柜合闸线圈连续烧损故障分析

对10 kV开关柜断路器频繁烧损合闸线圈的原因进行了分析,判定为断路器底盘车内机械拉杆变形导致断路器机械合闸闭锁装置失灵,并从断路器的搬运、验收开关柜的制造质量等方面提出了相关防范措施。     

基于IEC61850的断路器剩余电寿命监测系统设计

基于触头相对电磨损与相对电寿命法研究断路器剩余电寿命监测功能,并依据IEC61850标准构建数学模型。通过实时监测分/合闸电流及次数实现对电磨损量的监测折算,在此基础上构建适应IEC61850要求的电寿命监测分析系统。该系统可实现采样值的数字化传输与逻辑节点的无缝衔接,确保电流采样和分合闸位置监测数据并行传输时的传输实时性与一致性。实例分析表明,该断路器剩余电寿命监测系统稳定可靠,具有工程应用价值。     

The effect of DC offset on instantaneous operating characteristicsof low-voltage circuit breakers

This paper addresses the effect of asymmetrical currents on factory adjustments and field verification of low-voltage circuit breaker instantaneous trip units. Both molded case circuit breakers (MCCBs) and power circuit breakers are pertinent. Factory adjustment of low-voltage circuit breakers, based on test results using asymmetrical current, may cause the circuit breaker instantaneous unit to perform improperly and result in inadequate protection and coordination of electrical system apparatus. Similarly, field testing conducted to verify proper performance of low-voltage circuit breakers, using asymmetrical current, may lead to the erroneous conclusion that the circuit breaker's instantaneous unit is out of specification. In addition to addressing the difficulties presented by this phenomenon, this paper also proposes an approach to identifying and overcoming these testing difficulties     

一种断路器开断燃弧时间检测新方法

准确测量断路器燃弧时间的关键是确定电弧的起弧时刻.根据断路器开断时开断电弧的模型,详细分析了断路器开断前后电流的变化过程和开断相角等因素对燃弧时间的影响,提出了一种基于暂态电流的燃弧时间检测方法.通过对线路发生故障后的部分故障线路的三相电流录波数据滤波后进行拟合,预测之后的电流变化,并与实际电流数据比较,求得电流畸变量.当畸变量大于设定阈值时,即可认为该时间点为断路器的触头始分点;断路器首开相的触头始分点即起弧时刻.开断完成的时间点即熄弧点为相电流小于设定阈值的时间点,末开相的熄弧点为熄弧时刻.起弧时刻与熄弧时刻之间的时间差为断路器的燃弧时间.利用电磁暂态分析程序EMTP仿真证明了该方法的可行性和较高的可靠性.     

考虑电动力效应的高压断路器动力学特性仿真分析

创新地利用多体动力学仿真软件包ADAMS建立了VSl型真空断路器操动机构的动力学模型，并用试验对模型的有效性进行了验证。同时，还建立了真空断路器电动力计算模型，将开断和关合过程中的电动力分为洛仑兹力和霍尔姆力。以上述两个模型为基础，对断路器短路开断过程进行了仿真，研究了不同的开断条件下电动力对断路器机械特性的影响，从而为断路器的优化设计和状态检测提供了必要的理论依据。此后采用试验的方法对仿真结果进行了部分验证，验证结果表明，仿真在一定程度上揭示了断路器的运行规律。     

应用PTC限流元件的低压断路器

传统的低压断路器由于依靠电弧来消耗电弧分断能量,所以分断能力受到约束。本文介绍一种新型的PTC限流元件,它与传统断路器组合后,能吸收大部分的分断能量,从而大大提高断路器的分断能力。     

测量仪器输入阻抗对断路器分合闸速度的影响

进行断路器的型式试验时,国家标准要求测量断路器的机械特性,一般利用滑动电阻器测量断路器分、合闸速度。通过对测量设备的输入阻抗对测量精度影响的讨论分析,明确了输入阻抗与测量精度的关系,有利于测量时设备的正确选择,保证测量结果的准确性。     

特高压断路器的瞬态恢复电压研究

结合晋东南—南阳—荆门1 000 kV特高压试验示范工程，研究了交流1100 kV断路器瞬态问题中的断路器开断短路电流或失步解列后的瞬态恢复电压(transient recovery voltage，TRV)内容。在此基础上提出了我国交流1100 kV特高压断路器的工作条件建议，分析了特高压断路器TRV问题的前景。认为我国特高压电网断路器在不采用分闸电阻的条件下，可满足IEC断路器扩展标准和正在修订的我国电力行业断路器标准中对TRV的要求。     

核电厂发电机出口断路器失灵保护设计

核电厂发电机机端与升压变压器之间都装设发电机出口断路器,而且装设了发电机出口断路器失灵保护。文中分析核电厂发电机所配置的保护及其定值,发现发电机出口断路器失灵保护设计存在问题:某些启动跳发电机出口断路器、灭磁、关闭主汽门的电气保护,因电流判据不满足而不能直接有效地启动发电机出口断路器失灵保护;汽轮发电机组在程序跳闸过程中,发电机出口断路器发生故障而不能跳开,也不能启动发电机出口断路器失灵保护。对上述问题所造成的危害,文中提出核电厂发电机出口断路器失灵保护设计的改进措施,完善了核电厂发电机出口断路器失灵保护设计。