Effective Protection Distances of Low-Voltage SPD With Different Voltage Protection Levels

If surge protection devices (SPDs) are installed without consideration of the concept of lightning protection zones, the equipment to be protected might be damaged despite the correct energy coordination of SPDs. This damage is induced by the reflection phenomena on the cable connecting an external SPD and the load protected. These reflection phenomena depend on the characteristics of the output of the external SPD, the input of the loads, and the cables between the load and the external SPD. Therefore, the SPD has an effective protection distance under the condition of the specific load and the specific voltage protection level of SPD. In this paper, the equipment with different load characteristics and SPDs with different voltage protection levels are analyzed combinatorially under the operation of the surge combination wave. The influence of voltage protection level on the effective protection distance is discussed. Moreover, the effective protection distance of the SPD with the same parameter in a different voltage protection level is also analyzed in detail. The analyzed results show that the effective protection distance would be very long if the impedance of equipment is close to or smaller than the characteristic impedance of the connecting cable.     

Driving high surge currents into long cables: more begets less

Reality checks can and should be applied to proposals for characterizing the surge environment and application of surge protective devices (SPDs) to end-user, low-voltage power systems. One such check is the fact that driving a large current with steep front toward an SPD installed at the far end of a branch circuit cable could require such a high voltage that the connections at the near end of the cable will flashover, limiting the stress applied to the far-end SPD. Tests and numerical modeling were performed to support this thesis. The results of real-world measurements and modeling, presented in this paper, are in good agreement and validate each other. From that point on, the model allows parametric variations of power cable length and surge current amplitude and waveform, of which several examples are presented     

电源电涌保护器与被保护设备之间连接导线长度的计算

根据防雷规范的计算方法和实际条件,计算了末级电源线路电涌保护器（ SPD）与被保护设备之间的连接导线避免振荡保护距离和感应保护距离长度。计算结果表明,设计时末级电源SPD与被保护设备之间的避免感应保护距离和避免振荡保护距离应为6.36 m。     

限压型低压电涌保护器级间配合研究

采用电磁暂态程序(EMTP)仿真方法,研究了MOV限压型低压电涌保护器(SPD)两级保护电路.模型中采用传输线模型仿真电缆线,通过实验测量SPD在不同冲击电流下的残压值获得SPD仿真的必要电流和残压值参数.得到了两级在不同冲击电流大小、线缆长度连接时的电流分布情况和残压大小.对传输线的长度为5、10、20 m,冲击电流为8.9 kA时的仿真结果进行实验验证,实验结果和仿真结果基本一致.该项研究有助于雷电防护中SPD辅助工程设计.     

线路电阻对SPD配合的影响分析

为了准确分析用于低压配电系统过电压防护的多级浪涌保护器(SPD)的配合问题,通过建立SPD配合电路的拉氏运算方程,求解并分析线路电压降的解析解,理论研究了线路电阻对低压系统SPD配合的影响,指出忽略线路电阻将使通过后级SPD的电流被夸大,造成配合分析的不准确。理论分析表明,在前级SPD的残压一定的情况下,2级SPD间的电压差主要由后级SPD的V-I特性曲线、线路电感和线路电阻共同决定。通过对多种线路模型的SPD配合进行仿真计算,验证了理论分析的正确性。     

电涌保护器应用中几个问题的探讨

探讨了电涌保护器（SPD）应用中的4个颇有争议的问题，这就是SPD的响应时间、多级SPD的动作顺序、不同波形中冲击电流的等效变换以及SPD的残压与冲击电流峰值的关系。最后说明了SPD应用中各电压之间的相互关系。     

多级电涌保护器系统能量配合的应用

分布于建筑物的电源线路,通过设置多级电涌保护器（SPD）以释放雷电能量。SPD的布局及其相互的能量配合机制将直接影响保护效果。根据建筑物防雷区域和保护设备的需要布局SPD,形成多级SPD系统。分析了多级SPD能量配合的方法和保护机制,讨论各级SPD的参数选型,给出多级SPD系统能量配合的应用实例。研究表明,电源线路多级SPD系统中,需要各级SPD能量配合,才能形成系统防护效果。     

多分支系统中SPD配合的研究

通过理论分析和软件仿真,研究了低电压系统中多分支电路对开关型SPD和限压型SPD之间的配合,及限压型SPD间配合的不同影响.研究表明,各支路波阻抗的并联效果有利于设备的保护,使MOV型SPD间的配合效果提高,但开关型和MOV型SPD配合时,易造成开关型SPD不动作,在工程实践中应予注意.     

电涌保护器的工作机制与应用分析

在电涌保护器（SPD）的结构、工作原理及工作参数基础上,讨论了SPD对雷电电涌的限压、分流机制,并给出了信号线路SPD的选型实例与分析。明确在雷电环境中,信号线路SPD通过限制暂态过电压和分流浪涌电流以保护线路及连接的设备正常工作。对选用SPD保护通信线路（或输电线路）及其连接设备不受雷电电涌破坏具有指导意义。     

低压配电系统中浪涌保护器配合机理

利用波过程理论和集中参数电路方法,研究了浪涌保护器(SPD)的配合机理问题。在利用波过程理论研究SPD的导通次序时,考虑了负荷对SPD导通次序的影响,给出了多种配合情况下SPD导通次序的判断公式。通过建立两级SPD配合的集中参数电路方程,分析了不同的导通次序对各级SPD分流浪涌电流的影响,并给出了SPD通流分配计算公式。给出了不同SPD导通次序下的SPD配合框图,进一步解释了SPD间的配合机理。文中对不同线路参数的SPD配合电路进行ATP-EMTP软件仿真,研究了线路参数对SPD配合结果的影响。     

电缆铺设对气象设备的防雷效果对比分析

安装在野外的气象设备一般需要输电线路提供电源,出于工程施工方便输电电缆往往采用架空方式铺设,由于架空电缆容易感应雷电脉冲,造成后端连接的设备受到冲击而损坏.为了分析研究输电线路不同铺设方式是否有不同的防雷效果,通过建立等效模型对输电电缆自身分布电容电感特性进行分析,以及对电缆不同铺设方式引起分布参数变化的分析,利用电缆分布参数能够对雷电脉冲产生的衰减作用,得出了电缆埋地铺设对系统设备具有较好的防雷效果.工程实例表明,供电电缆半埋方式效果一般,直埋入土壤防雷效果最佳,而且埋地长度越长防雷效果越好.     

A study of modeling of EMTP analysis for indoor distribution line

Damage to home electric appliances due to lightning surges has recently become more common. The installation of SPDs (surge protective devices) in interior wiring is a countermeasure against damage and is also becoming more widespread after amendment of the regulation on indoor wires in 2005. Past study showed an effective method in which the earth line of the SPD is connected with that of home appliances and is grounded at one place in the home. However, because the methods of installing the distribution line in homes vary, it is difficult to estimate the effect of SPDs in every home, and high‐precision analysis by EMTP for interior wiring and SPD in the home is required. In this study, experiments were conducted with interior wiring and varistors, which constitute SPDs, and this paper reports the results of those experiments and of EMTP analytical models. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 175(4): 24–33, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21062     

振荡波两级低压浪涌保护器配合情况的实验研究

在房屋引入线处和临近灵敏设备处安装的串级式浪涌保护器,要求能以每一级最佳的工作方式共同有效地抑制系统中的过电压。对振荡过电压下两种不同浪涌保护器的配合进行了实验研究,并计算了各压敏电阻上所吸收的能量,分析了各种配合的有效性。     

Surge transference through transformers

The article demonstrates the need for secondary surge protection on main utility tie transformers and low-voltage substation transformers. Investments in these surge protection devices are minimal and an insurance against insulation failures. A more elaborate transformer model could be used in EMTP simulations, however, the results based on the simplified transformer inductive/capacitance model are valid for practical purposes. The modeling of surge phenomena on EMTP is complex, and a modeling of all the possible surges of atmospheric origin or generated within a distribution system will be time consuming. The cost of providing secondary surge protection on unit transformers is rather small, though a coordination of the surge arrester characteristics is required. Considerations should be applied to the overvoltage withstand capability of solid-state protective devices, ASDs, and monitoring and control equipment, which is much lower than the insulation levels associated with the power equipment.     

现代架空线输电系统中的高压电缆段(英文)

Electrical power transmission is dominated by overhead line systems at present.This is mainly based on more than hundred years of experience of utilities in running overhead lines.Furthermore,overhead lines have proven their operational reliability and functional assurance.In the past,cables were used in distribution networks in urban areas for the most part with the exception of direct current submarine cables.New developments of high voltage XLPE cables make it possible to use this technology for EHV level applications in transmission networks.Within this paper,mixed network configurations,consisting of overhead lines and high voltage cables,are investigated.An exemplary EHV transmission line with a total length of about 100 km,which is quite typical for Central Europe,has been studied.Several different line combinations are discussed with varied rates between overhead line sections and cable sections length in practice.The length of the cable sections are ranging from several kilometers up to lengths of 100 km.In this paper the work focuses on the transient behavior of combined 400 kV overhead and cable lines during switching processes and lightning impacts.A number of calculations were carried out to get an overview of the transient stress in numerous network nodes along the transmission system.Numerical programs like ATP/EMTP have been used for these simulations.Peak values and wave shapes of the transient voltage stress have been evaluated,based on different systems and within possible combinations.In respect of the insulation coordination and transient stress at network nodes,the voltage-time trends are also analyzed.The combination of high voltage overhead and cable transmission systems,especially such with lengths of more than about 50 km,are making tightened and extended demands to the network design,to the operational management and of course to the network protection also.As an output of this investigations,the results might influence the strategy in running this new type of combined transmission systems.     

大型光伏发电站防雷研究

大型光伏发电站户外场的雷击及过电压侵入是光伏发电的重要威胁之一.采用仿真软件对光伏户外场的光伏电池阵列、汇流箱、逆变器和浪涌保护器（SPD）等设备进行建模仿真,研究不同雷电流幅值、不同接地电阻和不同雷击位置对光伏电池板的危害,以及过电压侵入波所产生的危害,并通过降低接地电阻和加装SPD改善光伏发电站户外场内设备的过电压,取得了良好的防雷效果.     

大型光伏发电站防雷研究

大型光伏发电站户外场的雷击及过电压侵入是光伏发电的重要威胁之一。采用仿真软件对光伏户外场的光伏电池阵列、汇流箱、逆变器和浪涌保护器（SPD）等设备进行建模仿真,研究不同雷电流幅值、不同接地电阻和不同雷击位置对光伏电池板的危害,以及过电压侵入波所产生的危害,并通过降低接地电阻和加装SPD改善光伏发电站户外场内设备的过电压,取得了良好的防雷效果。     

Protecting load devices from the effects of low-side surges

Wherever lightning and poor utility power system grounds exist, distribution secondary systems are subjected to high-voltage surges due to lightning current seeking ground through low-voltage circuits. Utilities are becoming aware of this low-side surge phenomena and are taking measures to protect their distribution transformers' secondary windings. These measures can increase the voltage stress at the customer service entrance. If any ground paths exist on the customer side of the service entrance, surges can penetrate further into the customer's system and damage loads. Damage caused by low-side surges can be avoided if properly coordinated arresters are installed at the transformer secondary, at the service entrance, and at load devices. This work describes the secondary surge phenomena and the importance of protecting the service entrance and critical load devices effectively, especially when the transformer secondary is protected. A properly coordinated and effective protection scheme is described and recommended     

控制电缆电阻值超标问题分析及实例计算

变电站运行中控制电缆电阻值超标极易带来事故隐患。采用实测的电阻值超标的控制电缆数据,对不同用途（控制及信号回路电缆、测量表计电流回路电缆、保护电流回路电缆、电压回路电缆）下控制电缆的长度进行了计算,得出该型号电缆在实际工程中使用的极限长度,为电力电缆设计、工程施工提供参考。     

防雷接地设计中电涌保护器的应用

主要介绍了电涌保护器(SPD)的分类、保护水平Up与被保护设备的关系和配合.探讨了在不同的配电系统中如何根据接地形式正确选用SPD.