变压器信号源内阻与传输线负载阻抗匹配研究

变压器作为电压的转换装置,在各种自动化、机械化设备中起到了关键作用。为此,为提高变压器性能,研究一种新的变压器信号源内阻与传输线负载阻抗匹配方法。该方法首先利用增大测量回路电阻法测量变压器信号源内阻值,然后利用史密斯图法计算传输线负载电阻,最后利用模拟退化智能算法实现变压器信号源内阻与传输线负载阻抗匹配。经测试,结果表明:与两种传统阻抗匹配方法相比,所提方法的变压器信号源内阻与传输线负载阻抗匹配度达到最大,说明所提方法性能更为优越,有效提高了变压器的可靠性和稳定性。     

A frequency dependent transmission line model for a counterpoise

This paper has proposed a methodology to obtain a frequency dependent distributed‐parameter model for a buried bare conductor employing a time‐domain fitting from measured transient voltages and injected currents. The transient characteristic impedance and propagation function are expressed by a rational function in a z‐plane and a genetic algorithm (GA) has been used as an optimization tool. Frequency dependence of the per unit line parameters (RLGC) is derived from the obtained propagation parameters. Simulation results by the proposed model agree well with that from the measured results. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

基于传输线变压器的高功率合成器设计

为了实现高功率和超宽带,在短波及超短波频段的宽带固态发射机中,通常采用传输线变压器理论设计多路功率合成器,解决发射机功率合成的关键技术.采用降阻抗和升阻抗的设计方法设计出四路合成器,简化合成级数,通过功率设计、热仿真设计,成功设计出2～30 MHz的5 kW四路合成器,插损≤0.25dB,电压驻波比≤1.25,功率加载...     

Application of Haar functions for transmission line and transformer differential protection

The development of algorithms, based on Haar functions, for extracting the desired frequency components from transient power-system relaying signals is presented. The applications of these algorithms to impedance detection in transmission line protection and to harmonic restraint in transformer differential protection are discussed. For transmission line protection, three modes of application of the Haar algorithms are described: a full-cycle window algorithm, an approximate full-cycle window algorithm, and a half-cycle window algorithm. For power transformer differential protection, the combined second and fifth harmonic magnitude of the differential current is compared with that of fundamental to arrive at a trip decision. The proposed line protection algorithms are evaluated, under different fault conditions, using realistic relaying signals obtained from transient analysis conducted on a model 400 kV, 3-phase system. The transformer differential protection algorithms are also evaluated using a variety of simulated inrush and internal fault signals.     

Design of multi-band multi-section transmission line transformer using particle swarm optimization

The design of N _t -section matching transformer operating at N _t arbitrary frequencies using the particle swarm optimization (PSO) method is presented. Although analytical methods based on standard transmission line theory can be used in such designs, however, the analysis becomes cumbersome if N _t exceeds two, and numerical methods should be used to solve the resulting nonlinear equations. The design using the PSO, however, is much easier, and gives the same results as the analytical methods. Different examples are presented and compared with published literature.     

Partial discharge localization in transformer windings using multi-conductor transmission line model

Multi-conductor transmission line model (MTLM) of transformer winding has been used to find partial discharge (PD) location in transformers. To decrease computational complexity of the model, two methods for calculation of model parameters were studied and the most suitable method was chosen based on comparison between measured and calculated transfer functions of a 132 kV/20 kV transformer. To investigate the accuracy of MTLM in PD localization, PD pulses produced by a PD calibrator were injected into different points of a research 20 kV/0.4 kV transformer and measured at both ends of the winding. The sectional winding transfer functions computed by the model were used to refer measured PD signals to possible PD locations. Then by comparison of referred signals, PD location in the winding was estimated.     

Characteristic analysis of a wideband balun transformer having a delay line element for phase compensation

The balanced‐unbalanced transformer (balun) is extensively used in radio communication and measuring instruments. In recent years, with the development of television and portable telephones, wideband transformers tend to be miniaturized. In this paper, the wideband transformer is analyzed in terms of distributed coupled‐line theory. A main result of the analysis is that the balance and unbalance transmission characteristics of the balun are markedly improved in the high‐frequency range by using a delay line element for compensation. If the connection point S_w between the coil winding and delay line is off the ground, the balance transmission band is about doubled in the low‐frequency range. If the point S_wis grounded and if the impedance ratio m² is small, a higher degree of unbalance attenuation can be obtained. Better balance transmission characteristics can be obtained when the matching factor K approaches half the optimum. In addition, we show that an in‐phase or anti‐phase transformer can be made on the basis of our isolation wideband transformer. The equivalent circuits of in‐phase and anti‐phase wideband n:1 transformers are obtained from our theoretical analysis and these can be formed by the same transformer. The transmission characteristics of in‐phase and anti‐phase wideband transformers are analyzed and improved characteristics are obtained in the high‐frequency range. The theoretical and experimental values agree well over the wide frequency range of 100 KHz to 1000 MHz. ©1998 Scripta Technica, Electr Eng Jpn, 126(2): 1–14, 1999     

一起110 kV线路故障引起主变后备保护动作的原因分析

在一次110 kV线路因覆冰影响发生单相接地故障时,造成线路保护与主变中压侧后备保护同时动作,经变电站运行人员检查设备动作情况,确定线路开关确已分开,主变中压侧后备保护动作并非线路开关拒动引起.进一步对主变中压侧后备保护的动作行为进行了分析,确定了主变中压侧后备保护动作的原因为零序过流保护与零序方向过流保护因灵敏度不同,造成保护失配,最后提出了应该吸取的经验教训.     

Positional protection of transmission line using fault generatedhigh frequency transient signals

This paper presents a new technique for high-speed protection of transmission lines, the positional protection technique. The technique uses a fault transient detector unit at the relaying point to capture fault generated high frequency transient signals contained in the primary currents. The decision to trip is based on the relative arrival times of these high frequency components as they propagate through the system. Extensive simulation studies of technique were carried out to examine the response to different power system and fault conditions. Results show that the scheme is insensitive to fault type, fault resistance, fault inception angle and system source configuration, and that it is able to offer both very high accuracy and speed in fault detection     

750kV主变压器超高频局部放电在线监测

在银川东750kV变电站投运的＂750kV变电站电气设备绝缘状态在线监测系统＂,采用超高频局部放电检测技术（UHF）实现了对750kV主变局部放电缺陷的监测。介绍了750kV主变超高频局部放电检测的技术特点及实现方式,并对其应用效果进行了分析。     

甘肃陇南地区早成线低频振荡分析

对甘肃陇南地区早成线出现的低频振荡现象进行了描述,基于电力系统综合分析程序对陇南电网进行了小干扰计算,通过对比不同运行情况下电力系统稳定器投入和退出小干扰计算结果,得出结论:若发电机机组的PSS参数设置不合理,不仅起不到抑制低频振荡的作用,反而会进一步削减系统的阻尼,使系统更容易发生低频振荡。建议位于网架变化较大电网的发电机组,重新进行发电机组的参数测试,并进行系统联调试验,得出最佳的电力系统稳定器参数,保证电网安全稳定运行。     

电力变压器频率响应分析法综述

电力变压器频率响应分析法在系统运用多年,在实践中积累了不少经验,为检测变压器绕组变形提供了有效的技术支持。文中总结了频率响应分析判断方法以及实际应用频响法测试中的影响因素分析,并对频率响应分析法技术进行了展望。     

High frequency model of transformer winding

A high frequency model of transformer winding is used to analyze the voltage oscillations due to various excitations such as the very fast transient overvoltage which occurs at the time of disconnecting switch operations. Usually, a circuit of interlinked inductances and capacitances is used for this purpose, in which circuit parameters have to be properly determined. Previously, those constants have been estimated taking the coil section pair as a unit. In the method proposed here, the section pair can be further subdivided. The time‐domain calculation is conducted combining the frequency analysis and FFT technique. The voltage oscillations of the winding subjected to the lightning impulse are calculated. The correspondence with the experimental results is satisfactory. The response to a chopped impulse shows this method's applicability to high frequency analysis. Since the constants are calculated directly from the design parameters of transformer winding, this technique is particularly useful in developing and designing transformers. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(3): 8–16, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10280     

变压器在线监测探讨

论述了国内外变压器在线监测的基础研究领域近期的发展现状,介绍了变压器在线监测涉及的基本概念,以及两种基本的检测方法：局部放电法和变压器油色谱分析法。     

超声电机阻抗匹配变压器的设计

在超声电机特性阻抗分析的基础上、从阻抗和电感匹配的角度,提出了目前超声电机常用的推挽逆变电路中脉冲变压器的设计准则,并进行了实验验证,效果良好。     

输电线路工频电磁场监测分析及防护措施

为研究高压输电线路的电磁辐射,对黑龙江省220 kV和110 kV单、双回输电线路进行了监测,并对监测结果进行了分析.结果表明:高压输电线路工频电磁场强度随测点距离中心导线对地投影距离的增加而减少,电磁场强度随输电线路对地高度的增加而减少.据此,针对输电线路工频电磁场的影响因素提出了防控制措施,以期待治理输电线路电磁辐射造成的污染.     

A new transmission line fault locating system

The paper describes a new fault locating system that has been developed at Mehta Tech, Inc (USA). The distance calculating technique of the system is based on the reactance method of fault distance estimation, using data from one terminal of a transmission line. The technique compensates for errors caused by factors such as load flow and fault resistance. The system has been in commercial use by some reputable electric utilities, both local and international for over three years. The paper also presents some field results that have been obtained from some of these electric utilities that are using the new fault locating system     

长线频域测试法研究

本文根据长线传输理论,提出了一种通过长线端口的频率特性来推算其工作状态和各种参量的频域测试法。与传统长线的空域测试法相比,它具有不破坏长线的原工作状态、自动化程度高、测量迅速的特点;其误差可以分析和控制。特别是“频域测试法”可以直接观察传输线的工作状态与负载随频率变化的特性,在高频电信号传输和辐射工程中有很大实用价值。文中给出了长线“频域测试法”的理论分析和测试实例。     

Accuracy of LLP system and lightning frequency map evaluated from transmission line faults

The accuracy of an LLP system and a lightning frequency map are evaluated by using transmission line faults in the Hokuriku area from November 1993 to October 1996. The accuracy and efficiency of the system are calculated by statistical methods. From these results, a lightning frequency map with a 10-minute grid was proved that can replace the Isokeraunic Level Map with a 15-minute grid now used for lightning protection design. However, the correlation between the number of detected lightning flashes and transmission line faults in each mesh was found to be weak. This result suggests that a more detailed analysis taking into account the length of the transmission lines in each mesh is necessary. The correlation is stronger in winter than in summer, despite the fact that there is a difference in the lightning current distribution in each mesh in winter. This characteristic can be explained if upward flashes from transmission lines are dominant among lightning faults in winter. © 1999 Scripta Technica, Electr Eng Jpn, 129(4): 45–57, 1999     

500 kV紧凑型输电线路工频电磁场分布特性

对单回500 kV紧凑型输电线路和常规水平排列、中相V串布置的单回500 kV输电线路进行对比测试,分析得出500 kV紧凑型输电线路的工频电场、磁感应强度分布特性,并对不同导线排列方式的架空线路工频电场、磁感应强度分布规律进行比较分析.