避雷针保护范围的计算方法

常用避雷针(这里仅指单针)保护范围的计算方法主要有折线法和滚球法,为此,就“折线法”和“滚球法”的计算进行了初步的分析和探讨,得出：“折线法”的主要特点是设计直观,计算简便,节省投资．但建筑物高度大于120m以上不适用;“滚球法”的主要特点是可以计算避雷针(带)与网格组合时的保护范围,但计算相对复杂,投资成本相对大。     

Modelling lightning performance of transmission systems usingPSpice

Understanding the lightning performance of a transmission line requires visualization of the current waveform of the lightning stroke, the voltage wave produced by the lightning current, the propagation of this voltage wave, and the possible flashover of insulators and/or lightning arresters. Without the use of a simulation program, this topic would be difficult to understand. PSpice was selected as the software to generate the appropriate data needed to demonstrate this phenomenon graphically. A discussion is given of the models available in PSpice which were used to simulate this physical phenomenon successfully. The models developed to simulate the insulator strings and lightning arresters are also presented. These models are crucial to the complete simulation, and a study is provided which uses all the models discussed     

The basis of conventional lightning protection systems

The study of lightning protection system design encompasses nearly 300 years. Yet, many of the original sources for common design practices used today remain obscure. This paper traces the significant developments in lightning protection from the late 1700s to the modern day. Emphasis is placed on significant events in the history that have had direct consequences in the establishment of design practices for lightning protection. It is also demonstrated that many of the design practices used today were subject to significant scrutiny and empirical qualification. Our intent is to familiarize the student of lightning protection design with the original literature, testing, and other noteworthy contributions to the design of effective lightning protection systems.     

基于雷电定位系统的浙江电网线路雷击跳闸率评估

通过雷电定位系统观测的基础数据,评估浙江电网110～220 kV线路的雷击跳闸率,探讨传统雷击跳闸率算法的缺点,提出了算法改进的建议.     

Optimization of cable terminations

This paper describes a study of various termination constructions for medium voltage cross-linked polyethylene (XLPE) power cables. A special device was used for electrical field measurements around the cable termination which made it possible to monitor how stress relief materials with different permittivity and placement of isolated or grounded embedded electrodes (EE) affected electrical stress grading. The results of measurements for each configuration were examined by mathematical modeling based on the finite element method (FEM). Finally, the selected constructions of cable termination have passed severe test conditions with load cycling     

Early streamer emission lightning protection systems: An overview

Early streamer emission (ESE) lightning protection systems are a relatively new approach to the perennial problem of lightning damage, and these systems may hold promise for a more effective protection against lightning. However, the scientific and technical basis for this improved performance is far from certain and the efficacy of these technologies remains open to question. In this paper we examine the physical basis for ESE devices and identify areas of controversy and gaps in our knowledge of lightning and lightning protection that need to be considered in assessing ESE devices and in their future development     

雷电信息分析显示终端在电力系统的应用

雷电信息分析显示终端（LIADS）是雷电定位系统的三个组成部分之一。根据雷电信息分析显示终端的特点，探讨了雷电定位分析显示终端在电力系统中的应用，提出了在电力系统中一些新的应用范围。这对充分发挥雷电信息分析显示终端的作用，提高电力系统的安全，经济，可靠运行水平，具有重要意义。     

A computer program for designing the lightning shielding systems ofsubstations

A computer program is presented for designing the shielding systems of substations. The program is based on the most up-to-date version of the electrogeometric model (EGM). The calculation method is made free from the conservatism of some earlier versions of the EGM by introducing rational revisions. Shielding designs for typical layouts are also presented     

Integrated metering and protective relay systems

The process of converting sampled analog signals to digital numbers using a low-cost microprocessor and an A/D converter for motor protection is considered. Distribution fault records, relay performance with extremely saturated low ratio current transformers, and advanced methods of protecting high-inertia drive motors are presented. The discussion also covers: digital filtering; range of operation of a digital overcurrent relay; the function of the anti-aliasing filter; advances in motor protection; rotor thermal model; and maintainable structured software     

Experimental and analytical studies of lightning overvoltages in wind turbine generator systems

This paper presents the results of the experimental and analytical studies undertaken for the lightning protection of wind turbine generator systems by using a reduced-size wind turbine model. In the analytical studies, the FDTD (Finite Difference Time Domain) method is used. This study focuses on the overvoltages observed at the wavefronts of lightning surges. The lightning strokes on one of the blades and on the nacelle were considered, and the experiments and analyses were carried out by considering the cases of summer and winter lightning. The voltages and currents at various positions on the wind turbine model were considered.     

Integrated protective systems for operational acceleration-inducedloss of consciousness

Systems that can protect pilots from not only acceleration-induced loss of consciousness (G-LOC) but also from exposure to chemical, biological, and nuclear weapons are discussed. Hazards such as fire, drowning, and ballistic injury are not considered. Physiological stresses, protection methods, and their impact on G capability at increased altitudes are examined, as are stresses induced by the environment (heat stress, cold stress, and cold water immersion). Sustained and short-duration acceleration effects are described. Requirements for protection against chemical, biological, radiological, and laser weapons and the incorporation of mission-enhancement devices are addressed. Concepts for integration of all of these elements are discussed     

Performance of protective rod gaps for medium voltage networks inthe presence of dust particles under lightning impulses

Single and multiple rod gaps are used for the overvoltage protection of various power system apparatus. These are mostly located outdoors and are subjected to particulate contamination in desert lands. This paper discusses the influence of pollution on the breakdown voltage and breakdown time of protective air gaps. The rod radius and its end profile are changed to find the configuration which is least affected by pollution. In addition, practical protective gaps used across transformer bushings are tested to check their performance in clean and polluted conditions. It is found that such pollution drastically changes the gaps performance. Specific recommendations are made regarding the choice of suitable protective rod gap configuration for arid regions     

s-Domain analysis of lightning surges in three-phase systems using nonuniform single-phase line model

Surge response of the transmission tower in a three-phase transmission system is computed using s-domain nonuniform single-phase transmission line modelling. First, tower top voltage is obtained considering the tower and the ground wire by excluding the effect of the phase conductors, and then the induced voltages on the phase conductors as a result of the current flowing through the ground wire are computed using the magnetic coupling between the ground wire and the phase conductors. The first step of the analysis is the formulation of the system response in the s-domain, and the second step is the frequency to time domain conversion, which is carried out using fast inverse Laplace transform (FILT). The voltages on the phase conductors and the voltages across the tower insulators are computed, and some of the results obtained using s-domain analysis are compared with those obtaining using electromagnetic transients program (EMTP). The effect of frequency dependence of the line parameters is investigated.     

Contamination performance of silicone rubber cable terminations

The authors describe the results of a systematic study of the performance of silicone rubber terminations under contaminated conditions. The terminations evaluated were of the 15 kV class cold shrink type for concentric neutral cables. They were evaluated in a fog chamber where the electric stress, water conductivity, water flow rate, and the deenergization time between subsequent fog chamber exposures were varied in order to alter the test severity. Changes in the surface hydrophobicity were monitored periodically by analyzing the samples using ESCA (electron spectroscopy for chemical analysis), SEM (scanning electron microscopy), and contact angle measuring techniques. The results indicate that the experimental conditions play a significant role in the outcome of the tests. It was demonstrated that the recovery of hydrophobicity can be studied by using several techniques     

Comparison between utility sub-station and imitative earthing systems when subjected under lightning response

A comparison study between the utility substation and imitative earthing systems under lightning response is investigated. The utility sub-station is a non-operational sub-station, and the imitative earthing system is the earthing system that is purposely built to emulate the real earthing systems. However, no equipment is placed or connected to the earthing systems. The imitative earthing system is of a smaller size and is built separately at a different site. Both sites were designed according to the IEEE standard 80. Earth resistance measurements at low magnitude currents and at power frequency were also conducted for both earthing systems based on the IEEE standard 81. When impulse tests were conducted for both configurations, surprisingly the post-ionisation earth resistance of the imitative earthing system under lightning response was found to be similar to those tested under low magnitude currents. However, for the utility sub-station, the earth resistance under lightning response was found to be higher than that designed at steady-state conditions. The results in terms of time delays were also found to be different than that found in literature.     

Lossless 2-ports between non-reactive terminations

Lossless reciprocal 2-ports between terminations with even impedance functions are considered. They are the unifying concept for the synthesis of FDNR and leapfrog RC-active filters in their most general form. The scattering matrix of lossless reciprocal 2-ports with respect to such terminations is defined, its canonic form deduced and the transfer of active power discussed. This scattering matrix is related to the usual scattering matrix of the same 2-port but with respect to unit resistance terminations. In such a way the precise structure of the 2-port as an LC ladder can be deduced from properties of the original transfer function and the termination impedances and the LC synthesis can be performed by conventional methods and programs. An exhaustive enumeration of the different cases that may arise is given. It can give a general outlook on the different RC-active filters that may be obtained.     

基于GIS平台对防绕击侧针应用方案的研究

微地形是影响绕击跳闸率的一个重要的因素.因此,防绕击侧针的应用必需考虑微地形的影响.基于地理信息系统(GIS)提出了考虑各种微地形条件下(线路大跨越河流、山谷,沿着山脊、山腰走向等)防绕击侧针的应用方案.并结合500 kV架空输电线路进行实例分析.研究表明此方案直观、形象,且易于对防雷措施进行管理,对实际防雷工程有参考价值.     

浙江电网雷电定位系统落雷密度图分级应用的研究

分析了浙江电网各地区2004~2006年线路雷击跳闸次数与落雷密度的相关性、3年间多次雷击跳闸的线路雷击故障点与落雷密度分布的相关性,从而发现高落雷密度区域线路雷击跳闸率高于低落雷密度区域的特点,据此提出了落雷密度图分级应用的初步设想。     

Comparative testing of simple terminations of high-voltage cables

In HV systems, cable terminations are one of the weakest links. The majority of failures occur on the ground shield side. This side is especially stressed by the electric field in free space connections. Field control and rigorous technological processes are key to reliable functioning. The first was realized for a century by stress relief cones in conjunction with solid dielectric fillings. Later, stress-grading nonlinear materials in the form of paint, tapes, and tubes were used with much success (see, e.g., [1]-[3] and their bibliography). In dc applications, which are the main interest of this paper, the falling resistivity-field characteristic effectively pushes the electric field off the shield terminus, where it is strongest.