电压互感器铁磁谐振过电压及防止

简要分析了ＴＶ（电压互感器）铁磁谐振过电压的。综合分析了下列谐振措施：ＴＶ开口三角线组接电阻或分频谐振装置,ＴＶ中性点经 地电阻接地或经ＸＸＱ－１０接地,在ＴＶ中性点串单相ＴＶ,采用抗谐振型电压互感器,提出了它们的适用范围。为城网改造,新建变电站ＴＶ的选型提供参考,以达到防止事故发生的目的。     

胜利油田电压互感器抑制铁磁谐振过电压研究

油田电网改造在提高电能质量的同时,配电网系统出线范围也相应变宽,而且由于电缆的广泛应用,10kV系统电容电流的范围从零点几安培上升到了几百安培。在这种情况下,中性点不接地系统中易发生基频铁磁谐振和分频铁磁谐振。一次消谐在不同的地区往往使用不同的方式,在油田电网中采取的措施是在三相五柱电压互感器中性点安装零序电压互感器,即在电压互感器高压侧中性点串接单相电压互感器。通过实践研究,在油田配电网中采取在三相电压互感器中性点串接零序电压互感器,以及在电压互感器二次绕组上安装微机消谐装置,来抑制电压互感器因为谐振过电压损坏事故的发生取得了良好效果。     

电容式电压互感器铁磁谐振及抑制

介绍CVT自身谐振典型事例。对CVT中几种阻尼装置进行了比较。特别对新型速饱和阻尼器存在的问题提出了对策,建议将铁磁谐振列为出厂试验。     

电磁式电压互感器铁磁谐振抑制的分析

以带PT合空母为例,提出等值计算模型和数值计算方法,对配电系统PT铁磁谐振过电压发展过程进行暂态仿真,对PT高压侧中性点接地电阻和高压侧等值电阻、系统中性点接地电阻和消弧线圈PT励磁特性等多个参数对PT铁磁谐振的影响以及各抑制措施的效果进行了分析,所得结论可为配电网PT非线性铁磁谐振的抑制提供参考依据.     

电磁式电压互感器铁磁谐振抑制方法分析

变电站的10kV、35kV电压互感器基本为电磁式电压互感器,该互感器的固有缺陷就是会与线路的对地电容等发生铁磁谐振,导致互感器高压熔丝熔断,甚至设备烧毁。针对该现象,分析了铁磁谐振的机理,比较了抑制铁磁谐振的方法,为故障的处理、预防提供了参考。     

电压互感器铁磁谐振及消谐措施

0 前言 电力系统中有许多电感、电容元件(如发电机、变压器、互感器等的电感;输电线路的对地电容及相间电容),它们可以构成一系列不同频率的振荡回路。当操作或发生故障时,外加的振荡频率等于振荡系统中的某一频率时,就会出现谐振现象,引起某些部分(或元件)出现谐振过电压。 谐振是一种稳定现象。因此,谐振过电压在操作或故障的过渡过程中产生,而且在过渡过程结束以后,较长时间内稳定存在,直到发生新的操作,谐振条件受到破坏为止。所以,谐振     

电压互感器现场单相校验法

电压互感器的现场校验是在设备停电的情况下 ,在安装地点接入标准互感器和升压设备 ,接通三相电源或单相电源 ,用互感器校验仪测出被校互感器在额定负荷和 1 / 4额定负荷下的误差 ,以判定其准确度是否合格。根据JJG 31 4 1 994《测量用电压互感器检定规程》的规定 ,在额定频率、额定功率因数及二次负荷为额定二次负荷的 2 5 %～ 1 0 0 %之间的任一数值内 ,0 .1～ 1级的测量用电压互感器的误差不得超过表 1的误差限值。表 1　测量用电压互感器的误差限值准确度级别比　值　差倍率因数额定电压百分值2 0 5 0 80 10 0 12 0相　位　差倍率因数…     

Application of common transformers faults diagnosis methods on biodegradable oil-filled transformers

Due to environmental concerns regarding the use of mineral oil, biodegradable oil is increasingly being used as an alternative dielectric fluid. This paper presents results of experiments performed in the laboratory on the use of biodegradable oils for transformer application. The investigations cover two important diagnostic techniques for insulation assessment: (i) an investigation of partial discharge (PD) activity and characteristics in such oils and (ii) an investigation of the standard hydrocarbon dissolved gas products produced due to transformer faults. The fundamental aim of the investigation was to provide information as to whether the existing analysis techniques of PD fault pattern recognition and dissolved gas analysis methods, developed for mineral oil, are valid when used for insulation assessment with biodegradable transformer oil. The experiments were conducted on test samples to simulate three common types of transformer faults: low-energy PDs, high-energy arcing/sparking, and overheating. For the purpose of comparison, the same tests were performed using a mineral oil (Shell Diala MX) and a biodegradable oil (Envirotemp FR3). Also, each oil type was tested at three different moisture levels and with or without the presence of solid insulating materials (pressboard). PD activity was monitored using the standard IEC60270 phase-resolved analysis method. The fault gases produced were extracted and analysed by standard gas chromatography methods. Test results indicate that the PD phase resolved patterns are, in general, similar for the two oil types and thus existing PD pattern interpretations can be used to distinguish different types of PD faults, e.g. corona versus surface discharges. However, the values of various discharge quantities (PD magnitudes, repetition rate, current, etc) are very different under the same test condition. The quantities and the trend of dissolved gases for faults in biodegradable oil are substantially different compared with mineral oil. For the PD fault, biodegradable oil was found to release only a limited number of gases. For arcing and overheating faults, the main key gas produced is different between the two oils. Also, the presence of cellulosic materials such as pressboard influences the extent of hydrocarbon gases dissolved in the oil. It was found that for biodegradable oil, fewer amounts of gases are produced as the oil gets wetter.     

铁磁谐振的分析预防与处理

分析了电力系统发生铁磁谐振的机理,指出发生谐振时产生的过电压与过电流对电力系统中的设备能够产生较大危害。通过对鹤岗供电区内以往发生的几起铁磁谐振现象的分析,针对目前的系统状况提出了一些预防谐振的方法及系统发生谐振时的处理建议。     

Dielectric response methods for diagnostics of power transformers

The dryness and aging state of oil-paper insulation is a key factor in both the short- and long-term reliability of a power transformer, since moisture has deleterious effects on dielectric integrity and insulation aging rates. Today, the water content of the cellulose in an in-service transformer is determined indirectly via moisture measured from oil samples, according to IEC 60422. This report summarizes the work performed by Cigre Task Force 15.01.09, and presents conclusions regarding the state of the knowledge on the applicability of the current diagnostic techniques.     

计及阻抗匹配平衡牵引变压器的电网短路计算方法

深入分析了阻抗匹配平衡牵引变压器的接线形式,分别提出了基于对称分量法的计及阻抗匹配平衡牵引变压器的电网短路计算方法以及基于相分量法的短路计算方法。给出了各种类型的故障计算公式。并将两种方法相比较,结合算例验证了方法的正确性和实用性。与基于相分量法的短路计算方法相比,基于对称分量法的短路计算方法更容易与现有普遍应用的基于对称分量法的电力系统故障计算程序相结合,只需在程序中添加相应的短路计算模块即可对阻抗匹配平衡变压器短路故障进行计算。利用所提基于对称分量法的计算方法开发的软件包已用于实际工程。     

电子式互感器数据传输方法的分析与改进

分析了当前电子式电压/电流互感器的数据传榆方案中存在的问题,在此基础上提出了改进的数据传输方案.方案包括数据传输的硬件结构设计以及串行通信协议.该方案采用CPLD作为通信控制器件,DSP作为接收数据的处理器件,简化了数据采集系统的硬件结构.通过全数字锁相环逻辑从曼彻斯特编码的基带信号中提取位同步信号,位同步精度显著提高,实现了可靠的串行通信.通信提供了可靠的误码检测手段,并对接收错误的数据采用Lagrange线性插值算法进行修复.分析与仿真表明该数据传输方案具有良好的性能.文中最后提供了一套设计实例作为电子式电压/电流互感器数据采集系统的设计参考.     

以科学为杠杆,撬动三峡工程的潜力

O前言 水电站所用的资源是水,来水时空分布的不均匀性、不确定性既涉及到防洪安全、泥沙淤积,又涉及到效益等各个方面.对于单一目标的电站是如此,多目标的水利水电枢纽也是如此,当然对于梯级电站则更是如此.因此,在对规律的认识和把握不充分的情况下,留有充分的余地是必然的选择.余地,也就意味着潜力.挖掘潜力的前提是对规律的认识和把握,途径是科学,即科学预测、科学调度、科学管理,还要解放思想,积极探索.     

地区电网采用高效变压器的节电潜力分析

对配电变压器的运行损耗进行了深入的分析,并根据3种变压器损耗算法建立了3种节电潜力评估模型。以广东电网公司某供电局的电网侧和该地区的用户侧配电变压器为例,分析了该地区电网更换低压配电变压器的节电潜力,结果表明,该地区电网低压配电变压器节电潜力巨大,若进行更换,可获得可观的效益。     

东莞配电网谐波对配电变压器危害分析

为了掌握电网运行的谐波状况及其危害,采用便携式电能质量分析仪FLUKE435对配电网变压器运行状况进行谐波普查,得到了大量典型负荷的实测数据.根据相关文献和标准中,对谐波造成配电变压器损耗增加(最高增加0.06%的损耗)、利用率下降(降容15%)、寿命减少(可减少寿命一半)和维修费用增加(最高增加一倍的费用)等问题进行...     

An application of dyadics to the analysis of power transformers

A simulation of power transformers following switching operations is presented in which each core section is represented by a non-linear inductance, the differential inductance being determined from the flux density in that section of the core. In analysing the resultant circuit model for the transformer it is shown that the circuit equations have dyadic properties which can be used to give a more efficient numerical solution.