Transient analysis of coupled non‐uniform transmission line using finite element method

This paper presents a finite element time domain model for a numerical solution of a coupled non‐uniform transmission line problem. On the basis of the finite element method, a novel numerical procedure for the solution of a system of the non‐uniform multi‐conductor transmission line equations in the time domain is presented. The results obtained by the proposed method have been compared with the solution obtained using the finite difference time domain method, and an excellent correlation has been demonstrated. Copyright © 2014 John Wiley & Sons, Ltd.     

On the uniqueness of the numerical solution of non‐linearly loaded lossy transmission lines

The purpose of this paper is to investigate the uniqueness of the solution of lossy lines with frequency‐dependent parameters terminated with non‐linear resistors. Several solutions that satisfy the same initial conditions may exist if the terminal resistors are locally active. In these cases the uniqueness of solution is assured adding parasitic capacitances in parallel to the voltage controlled resistors and parasitic inductances in series to the current controlled resistors. In this way, among all the possible solutions, the only one that assures the time continuity of the current and voltage waveforms at the ends of the line is captured. In the light of these results, the properties of numerical models of these distributed circuits based on convolution techniques have been studied, and conditions assuring the uniqueness of the numerical solution have been found. Numerical simulations, when based on qualitative information of this type, enable us to obtain the quantitative properties in an efficient manner. In particular, a simple numerical method that enforces artificially the time continuity of the solution is proposed to circumvent the need of adding parasitics. Copyright © 1999 John Wiley & Sons, Ltd.     

基于双曲正切函数相位特性的高压长线路故障测距新算法

提出一种基于双曲正切函数相位特性高压长线路故障测距新算法,其在将故障位置作为已知条件看待并引入参考点与之匹配的思想基础上,构建了一个和双曲正切函数具有相同相位特性的测距函数。根据所取参考点与故障点相匹配时测距函数相位等于零这一特征进行定位。该方法理论上不存在伪根,所需运算量远小于传统方法的运算量,能有效克服传统方法存在的测距精度和测距速度此消彼长的矛盾。EMTDC仿真结果表明,该方法不受过渡电阻、故障位置和故障发生角等因素的影响,在线路参数严重不均匀情况下依然保持较高的测距精度,具有较好的鲁棒性。     

基于在线参数计算的同杆双回线的自适应故障测距

提出一种新的基于相量测量单元 (PMU)在线计算输电线路参数的同杆双回线故障测距的自适应算法。该算法利用PMU装置获得同杆双回线路两端的电压和电流相量,在线路正常运行时,在线计算同杆双回线的正序参数,并将该参数用于故障测距,解决了线路实际运行参数与电力局提供参数的不同,线路参数在运行过程中由于过负荷,区外故障等原因引起线路参数的变化所导致的测距精度问题。通过故障前后线路两端的采样数据获取突变的同序正序分量,计算线路两端的等效系统阻抗,解决了线路故障前系统运行方式的不确定性所引起的测距误差。大量的EMTP仿真计算结果表明,该测距算法能自适应系统运行方式的变化,不受故障点过渡电阻、故障类型、故障距离等因素的影响,具有很高的测距精度。     

Generalized non‐uniform transmission‐line models for local radiation from microstrip bends in MMICs

Although microstrip bends in high‐speed digital MMICs have been widely investigated for the past two decades, their local radiation characteristics rather than their reflection characteristics have not been completely explored yet. In this paper, the generalized non‐uniform transmission‐line equations are used in analysing the microstrip bends including their local radiations. In our new models, the whole structure of a bend is regarded as a non‐uniform transmission line that is totally governed by the generalized non‐uniform transmission‐line equations. Except for analytical simplification and broad bandwidth performance, the new analysis could indicate where the strongly local radiations along a bend structure come from. Copyright © 2003 John Wiley & Sons, Ltd.     

输电线路工频参数测试新方法的研究

强干扰电压下线路工频参数的测量是一个较难解决的问题。为此,通过分析目前国内外工频参数测试技术的现状,介绍了基于同步电源的工频参数测试新方法的原理和现场测试方法。该方法成功地解决了强干扰电压下的一次线路工频参数的测量难题,对促进继电保护的运行管理水平和电网的安全稳定运行具有很大的推动作用。     

Observation of lightning at 500‐kV transmission lines (part 1)

We investigated the phenomenon of lightning strokes on 500‐kV transmission lines from 1984 to 1993. The investigation covered the recording of lightning paths by still cameras and measurements of lightning current at the lower part of transmission tower on 31 towers, over a 12.7‐km‐long section of the transmission line. We also observed lightning on an isolated tower at a nuclear power station. In the course of lightning observations spanning a 10‐year period, we have confirmed the suitability of the lightning protection design on transmission lines. The distribution of lightning incidence angle (θ) expressed in terms of (cos^mθ) was characterized by exponent m = 2 for the three‐dimensional observations and m = 3.5 for the two‐dimensional observations. No cases of shielding failure on 500‐kV transmission lines were observed. The ratio of lightning current at the top of the isolated tower to the lower part was about 11 to 1. In addition, the lightning current waveform at the top of the isolated tower was similar to that at the lower part. © 1999 Scripta Technica, Electr Eng Jpn, 130(2): 59–67, 2000     

平行双回线两点故障测距算法的研究

以分布参数作为高压输电线路的模型,对平行双回线一回线上两点异相故障及两回线上两点故障提出了一种新的测距算法。该方法利用线路两端电压、电流的正序和负序分量,不需选代计算,并适用于一点故障情况。其测距精度不受系统阻抗变化、过渡电阻及不同步采样数据的影响。仿真计算表明该方法有效     

同杆并架双回输电线路感应电压的计算

分析了两回线路同杆并架时停运线路上感应电压产生的原因,并进行了仿真计算,分析了接地线位置和接地电阻大小,导线排列,运行线路载荷及投切操作,杆塔接地电阻等因素对感应电压的影响。得出了接地线位置和其电阻的大小是影响停电线路上感应电压大小的重要因素的结论。     

带并补电抗线路电弧性故障固有频率特征研究

超/特高压输电线路发生电弧性故障时由于线路电容电感构成谐振回路会产生固有频率分量,利用并联电抗电流量的频率特征有助于实现线路保护的故障识别和重合闸的无故障判别。电弧性故障时先后经历一次电弧、二次电弧、恢复电压3个不同的物理阶段,各阶段分别由储能元件构成自振网络,由于各阶段自振网络结构的差异将产生不同的特征频率分量。通过相模变换实现三相耦合线路模量网络的固有特征频率的计算模型及特征分析,明确了利用并联电抗器电流的主要固有频率分量特征能够识别电弧性故障所处的物理阶段,为线路保护的故障识别和三相重合前的无故障判别提供有效的特征信息。最后PSCAD仿真分析结果表明,所分析的不同物理阶段的固有特征频率的相关理论的正确性,为下一步利用固有频率特征实现线路保护和重合闸方案提供了较好的理论基础。     

基于小波变换的超高压输电线路故障选相新原理

介绍了连续小波变换定义、基于多分辨分析的Mallat快速小波分解算法。根据超高压(EHV)输电线路故障暂态电流的特点。提出了基于小波变换能量特征的故障选相新原理和算法。借助MATLAB/SIMULINK仿真分析软件,研究了一实际电网EHV输电线路在区内不同故障条件下选相原理的有效性。结果表明,该方案是可行的。     

Single-ended time domain fault location based on transient signal measurements of transmission lines

Precise fault location plays an important role in the reliability of modern power systems. With the increasing penetration of renewable energy sources, the power system experiences a decrease in system inertia and alterations in steady-state characteristics following a fault occurrence. Most existing single-ended phasor domain methods assume a certain impedance of the remote-end system or consistent current phases at both ends. These problems present challenges to the applicability of conventional phasor-domain location methods. This paper presents a novel single-ended time domain fault location method for single-phase-to-ground faults, one which fully considers the distributed parameters of the line model. The fitting of transient signals in the time domain is realized to extract the instantaneous amplitude and phase. Then, to eliminate the error caused by assumptions of lumped series resistance in the Bergeron model, an improved numerical derivation is presented for the distributed parameter line model. The instantaneous symmetrical components are extracted for decoupling and inverse transformation of three-phase recording data. Based on the above, the equation of instantaneous phase constraint is established to effectively identify the fault location. The proposed location method reduces the negative effects of fault resistance and the uncertainty of remote end parameters when relying on one-terminal data for localization. Additionally, the proposed fault analysis methods have the ability to adapt to transient processes in power systems. Through comparisons with existing methods in three different systems, the fault position is correctly identified within an error of 1%. Also, the results are not affected by sampling rates, data windows, fault inception angles, and load conditions.     

Investigation of lightning tripouts on 150‐kV transmission lines in West Sumatra in Indonesia

Lightning activity in Indonesia is very high, and the ratio of lightning tripouts of the transmission line is also very high, reaching 66%. The results of our investigation show that a positive correlation exists between the number of lightning tripouts on a 150‐kV transmission line and the tower‐footing resistance and that the main cause of the tripouts is the back‐flashover. Moreover, it turns out that the flashover at the lower arm increases in case of high tower‐footing resistance. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A new false‐root identification method based on two‐terminal fault location algorithm for double‐circuit transmission lines

A fault location algorithm without synchronization for double‐circuit transmission lines does not require sampling synchronization, reduces the cost, and has a higher engineering value, but the algorithm still needs to be improved in the false‐root identification. This paper conducts further studies on this issue. First, the false‐root problem of the fault location algorithm without synchronization is analyzed, and then a new false‐root identification method is proposed, which is based on the difference of the existence of the false root in the calculation of the voltage amplitude along the line with different electrical moduli. It can solve the problem of the traditional method, which cannot distinguish between voltage amplitudes when they are close. Second, considering the shortcoming of the existing phase‐mode transformation matrix, a new phase‐mode transformation matrix applied to double‐circuit lines is deduced, which is based on the six‐sequence component method; it can be combined with the new false‐root identification method, thereby realizing false‐root identification under various types of faults. Finally, fault location is realized by using the moduli in the mold domain. The principle does not need to synchronize data in two terminals and is not affected by the fault types, fault resistances, and other factors. As is shown in a large number of Alternative Transients Program version of Electro‐Magnetic Transients Program (ATP‐EMTP) simulation results, the fault location has a higher accuracy © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

同塔四回输电线路故障选线新方案

从参数不对称同塔四回输电线路入手,结合四回线内部存在的线间及相间电磁耦合的特点,分析推导出适合的相模变换矩阵对各回线阻抗进行解耦处理,并且通过仿真对比的方式论证了解耦方法的正确性。基于解耦出的独立模量间的关系,定义4个参数K_1—K_4,根据这4个参数在不同回路故障时的取值不同,构造新的故障选线判据。大量的PSCAD/EMTDC仿真数据表明,所提出的故障选线方案速度快、简单、可靠,且不受故障距离、过渡电阻以及负荷电流和系统运行方式的影响。     

一种考虑对各种误差综合修正的线路双端测距算法

在输电线路故障测距的研究中,由于线路参数可能变化或提供的参数不准确,以及其他不利因素的存在,对故障测距的精度会产生很大的影响。该文提出了一种基于分布参数模型和等效参数估计的双端测距算法,该算法只利用故障前的电压电流,在线估计出线路等效参数,对各种误差能够起到综合补偿的效果,从而提高了测距精度。EMTP仿真结果表明,该算法较之不带参数修正的算法测距精度有明显提高,具有很强的参数自适应能力和收敛能力。     

Theory on asymmetrical coupled‐parallel‐line transmission and reflection zeros

This paper treats an innovative methodology on the synthesis mechanism of the coupled‐parallel‐line (CPL) transmission zero (TZ) and reflection zero (RZ). The CPL structure under study is configured as a reflection type distributed arbitrarily loaded stub circuits. On the basis of the equivalent Z‐matrix analysis, the CPL input impedance theoretical model is established. Mathematical analysis is performed to predict accurately the TZ and RZ frequency shifts in function of the CPL physical parameters. The input impedance behavioral model in function of asymmetrical CPL load parameters is determined. The TZ and RZ existence conditions are established. Then, the characteristic equations illustrating the TZ and RZ fundamental formulas in function of the CPL coupling coefficient and characteristic impedances are examined. Furthermore, innovative graphical representations of the TZ and RZ existence conditions in function of the CPL parameter ranges are explored. The developed CPL model was validated with different cases of simulated microstrip proof of concept. As expected, a good correlation between the TZ and RZ frequency shifts from the analytical calculations and simulations is obtained. The developed CPL model is useful for the TZ and RZ frequency shifts fast monitoring during the Radio Frequency (RF)/microwave circuit design phase. Copyright © 2017 John Wiley & Sons, Ltd.     

同塔多回输电技术特点及其应用分析

采用同样架设多回架空输电线路方式是解决输电走廊紧张矛盾的根本措施之一,阐述了采用这一技术的技术要点,包括杆塔结构、耐雷水平、线路保护故障判别、绝缘子型式的选择与环境影响、运行与检修特点等。并详细介绍了国内外应用情况。     

基于双端不同步采样数据的高压输电线路故障测距

提出了一种基于双端不同步采样数据的高压输电线路故障测距算法。该算法考虑了线路的分布参数特性,利用线路双端电压和电流量进行故障测距,从而保证测距不受过渡电阻的影响。对于不换位三相线路,采用模分量法,使相互耦合的相空间三相线路解耦为相互独立的模量。为了避免求解导数的复杂性,该文采用Powell方向加速法进行求解。仿真计算表明,算法对整个线路长度区间内的任何故障点都能精确测距。     

2010年全国输变电设施可靠性分析

通过对2010年全国220 kV及以上电压等级输变电设施可靠性分析,特别是对220 kV、330 kV、500 kV变压器、断路器、架空线路3类主要输变电设施的计划停运及非计划停运方面的分析,从技术及责任原因中找出影响其运行可靠性的薄弱环节,并通过设备型式、部件分析、进口与国产设备指标对比,找出了可靠性的变化趋势,为规划、设计、施工、生产等各环节电力企业制定确保输变电设施可靠性有效措施提供参考依据。