空心电抗器投切下的电场和电动力分析

针对频繁投切操作对干式空心电抗器绝缘产生的影响,为保障电力系统的安全稳定运行,文中采用仿真和实验分析的方法,对空心电抗器稳态和投切暂态下的电场和电动力进行分析。通过建立基于Maxwell的空心电抗器仿真模型,进一步比较两种状态下电场和电动力的分布特性及数值变化。研究结果表明,投切下的电场强度和电动力较稳态运行下均有明显增大,绝缘厚度需要达到0.032 5 mm才能约束投切过程中产生的径向电动力。投切暂态过程对电抗器绝缘厚度提出了更高的要求,为空心电抗器的工业设计提供了一定的理论依据。     

基于微功率无线射频技术的干式空心电抗器故障专家分析与在线预警系统研究

干式空心电抗器在运行时温度分布不均匀,存在局部过热现象,现在的温升试验方法不足以反映电抗器绕组的实际运行温升情况.因此找准其封包温度场的分布,分析确定关键发热部位或者高温范围,并依据封包内绝缘材料最高耐温极限值,采取有效的温度在线监测预警,至关重要.这样能及时发现设备各个包封温升情况,预防事故的发生和扩大.本文研究着重分析了微功率无线射频技术的干式空心电抗器故障专家分析与在线预警系统,期望能够为同行人士提供理论帮助.     

一种埋入式FBG应变传感器在干式空芯电抗器健康监测中的应用

为实现干式空芯电抗器的长期健康监测,提出了一种适用于强电磁环境的可埋入式光纤Bragg光栅(FBG)应变传感器。传感器结构简单且抗电磁干扰,可直接埋在干式空芯电抗器包封内。在包封制作过程中,将2个FBG应变传感器和1个FBG温度补偿传感器埋入在干式空芯电抗器的包封内,其中2个应变传感器分别按轴向和径向布设。温升实验结果表明,随着通电时间的增长,35kV干式空芯电抗器包封的轴向和径向应变量沿负向增加,约5h后趋于稳定,此时包封轴向应变量约为-3 200με,径向应变量约为-4 100με。埋入式FBG应变传感器稳定可靠,可实现极端环境下干式空芯电抗器的健康监测,对维护电网及电力设备的安全有重要意义。     

变电站中电涡流引起的危害和防范措施

本文以变电站干式空心电抗器电磁感应引起的围栏结构发热为例,分析了干式电抗器引起围栏结构发热的原因,并介绍了行之有效的处理办法,最后提出了几点对于电抗器使用安装的建议,希望对干式空心电抗器的布置安装设计、施工以及运行管理有一定的参考作用。     

空载输电线路的工频过电压仿真软件设计

本文以空载输电线路的工频过电压为研究对象,建立了在任意位置连接并联电抗器情况下的等效电路模型,获得了沿线电压表达式.在GUI基础上,设计了工频过电压仿真软件.分别介绍了该软件的交互式界面、基本功能和仿真实例.对空载输电线路的工频过电压进行了分析和演示,加深学生对工频过电压的理解和认识,增强学生的实践能力,对电力系统类教...     

基于阻抗特性试验的空心电抗器匝间故障分析要素浅析

本篇简述了目前空心电抗器匝间绝缘试验的技术现状,讨论了一种基于空心电抗器阻抗频谱测试方法的故障分析思路,重点分析了阻抗频谱的频谱特征、时域分布特性,并浅析了基于非破坏性阻抗频谱测试用于分析空心电抗器匝间绝缘特性的后续研究方向.     

基于平面结构的正交可控电抗器磁通特性分析方法

正交可控电抗器的三维磁路模型结构较为复杂,适用于分析正交电抗器某些特性,但无法直观表达该电抗器的磁路结构.文中提出一种平面结构用于分析正交可控电抗器磁通特性,并通过仿真软件FEMM对正交可控电抗器的平面结构,进行磁通分布情况和磁路结构的分析,该方法便于正交可控电抗器的磁通特性分析,通过磁通和磁势的仿真数据结果对比,可以进一步得到正交可控电抗器的磁路模型和磁动势方程.     

IEC60076标准草案中干式变压器的几项特殊试验

本文着重阐述了IEC60076-11<干式变压器>标准草案中规定的气候等级、环境等级、耐火等级的试验标准和方法.并与欧洲标准HD464/S1进行对比,以云变SCR包封型干式变压器的试验情况为例进行说明和讨论.     

双子表面活性剂14-3-14·2Br的表面活性与室内驱油实验

实验室合成了一种新型的双子表面活性剂14-3-14·2Br,并对其一系列表面性能进行了测定,在此基础上对不同浓度的表面活性剂驱油效率进行了室内研究。室内试验表明:14-3-14·2Br的临界胶束浓度为3.4×10-4mol·L-1,对应表面张力为22.7mN·m-1,具有较高的表面活性。通过对比,14-3-14·2Br的表面活性远远优于常用的表面活性剂。驱油实验研究表明,在水驱采收率很高的情况下仍可大幅度提高采收率,是一种性能良好的驱油剂。     

浅析同步发电机转子过电压及其保护

随着我国电力工业的迅速发展,发电机的额定电压随着发电机额定容量的增大而不断提高,以及可控硅整流励磁的利用,使得同步发电机转子回路的过电压问题更加显得突出。本文分析探讨了同步发电机转子回路过电压的几种来源,并以辽宁华电铁岭发电有限公司300MW发电机转子回路过电压保护为例,设计了一套较完整的保护方案,以供参考。     

Hole Mobility in Poly（N—vinylcarbazole） Thin Film Based on Silicium^①②

The mobilities of holes in thin,spin-casting films of poly( N -vinylcarbazole)(PVK) based on silicium are measured using a time-of-flight (TOF) technique.The drift of hole mobility is strongly dependent on the electric field and temperature.At room temperature and an electric field of 2×10 5 V·cm -1 ,the effective mobility of hole is 7.14×10 -6 cm 2·V -1 ·s -1 ,in a 200 nm thick sample.     

真空断路器投切电抗器过电压分析

对于变压器低压侧负荷较小的运行状况,使用真空断路器投切电抗器可能由于过电压造成设备损坏.本文分析了在投切电抗器过程中产生过电压的原因,提出了过电压抑制方案,并进行了试验验证,试验证明过电压抑制方案切实可行.     

青藏高原东北部双极性窄脉冲放电物理参数模型反演

利用青藏高原东北部青海地区三维定位数据和双极性窄脉冲电场波形同步数据,基于三种模型和粒子群优化算法,拟合并反演了双极性窄脉冲放电通道中电流峰值、通道尺度等特征参数,统计分析了不同传输线模型拟合得到的双极性窄脉冲的物理参数.结果表明：在基于流光-先导的准静电场传统空气热击穿机制的TL模型和MTLK模型中,相比TL模型,MTLK模型考虑了电流传输过程中能量的损耗,更符合实际;而基于准静电场相对逃逸雪崩击穿机制的MTLEI模型,相比较另两种传输线模型,表现为更窄放电通道内存在长时间随着高度呈指数递增的电流强度.三种传输线模型反演得到的电偶极矩范围为100～800 C·m,而更高处发生的双极性窄脉冲事件(narrow bipolar event, NBE)通常具有更大电偶极矩.     

Filter networks for long cable drives and their influence on motor voltage distribution and common-mode currents

Filter networks for long cable drives have been studied in the last decade to solve the overvoltage problem at the motor terminals. However, little research has been dedicated to analyze their influence on the voltage distribution in the motor stator winding and on the circulation of the common-mode currents. In this paper, the project of dv/dt filters through simulation and analysis from previous work is extended, including the motor voltage distribution and common-mode current analysis. Simulation and experimental results are presented, demonstrating the usefulness of the filter networks on the motor overvoltage mitigation. Three filter topologies will be discussed and compared here: RLC filter at the motor terminals, RLC filter at the inverter output and reactor filter, which is extensively used in the industry. Simulation and experimental results demonstrate that the RLC filter at the inverter output is the most interesting solution among the main types of passive filter networks.     

Electron Mobility in Tris（8—Hydroxyquinolinolato）Aluminum Thin Film Based on Silicium^①②

We have measured the mobilities of electrons in thin,vapor-deposited films of tris(8-hydroxyquinolinolato) aluminum(Alq 3) based on silicium using a time-of-flight(TOF) technique.The drift of electron mobility is strongly electric field and temperature dependent.At room temperature and an electric field of 2×10 5 V·cm -1 ,the effective mobility of electron is 1.0×10 -5 cm 2·V -1 ·s -1 for 200 nm thick sample.     

大模场低损耗光子晶体光纤的研究与设计

为了改善高功率光纤激光器的非线性效应,提出并设计了一种新型的无源、单模、低损耗、大模场的光子晶体光纤结构.利用时域有限差分法并结合完美匹配层边界条件,分析了光子晶体光纤有效模场面积的影响因素,得到光子晶体光纤性能随波长及几何结构的变化规律,从而得到实现更大模场面积的结构参量.结果表明,保证单模传输的情况下,在1.064...     

磁控溅射法制备Bi2Te3热电薄膜的研究

Bi2Te3薄膜是室温下热电性能最好的热电材料,利用磁控溅射在长有一薄层SiO2的n型硅样品上制备Bi/Te多层复合薄膜,经后续退火处理生成Bi2Te3。通过分析Bi2Te3薄膜的生长和退火工艺,探讨Bi/Te中Te的原子数分数对薄膜热电性能的影响。采用XRD和SEM对薄膜的结构、形貌和成分进行分析,并测量不同条件下的Seebeck系数。薄膜Seebeck系数均为负数,表明所制备样品是n型半导体薄膜,且最大值达到-76.81μV.K-1;电阻率ρ随Te的原子数分数增大而增大,其趋势先缓慢后迅速。Bi2Te3薄膜的热电性能良好,Te的原子数分数是60.52%时,功率因子最大,为1.765×10-4W.K-2.m-1。     

Repair-unit location models for power failures

Extreme weather conditions such as ice storms often cause significant damage to electric power transmission and distribution systems and result in large-scale power failures. In such cases, electric utilities need to repair the transmission and distribution systems as expeditiously and economically as possible. In this paper, for the electric utilities, the authors present three mathematical goal programming models: (1) a tactical model that provides the optimal repair-unit dispatch plan after a forecast of severe weather conditions; (2) a short-term strategic model that provides the optimal repair-unit location plan under normal weather conditions; and (3) a long-term strategic model that provides the optimal number of repair units. These models will assist electric utilities to locate and dispatch repair units and to restore the transmission and distribution failures efficiently. The authors illustrate some features of these models with a numerical example. Finally, a comparative study shows how these models could be more efficient than a modified conventional model     

Cost-effective design of an inverter output reactor in ASDapplications

In this paper, the cost-effective design of an output reactor which is used to suppress the overvoltage at the motor terminal in an adjustable-speed drive (ASD) application is proposed. The overvoltage suppression mechanism of an output reactor in an ASD application is analyzed and the dominant parameters of the output reactor for the overvoltage suppression are extracted. Using these parameters as the design values and considering the high-frequency characteristics of the iron core in the reactor, a new cost-effective structure of the output reactor is proposed. Experimental results of the conventional reactor and the proposed reactor with a 15-kW induction motor are given to verify the proposed scheme