Lightning Surge Characteristics Research Articles

A comprehensive lightning surge analysis in offshore wind farm

The structure of offshore wind farm is completely different from that onshore, and it is threatened by intruding lightning surge from various routes. Little attention has been paid to the electric equipment installed on offshore power station so far. A comprehensive lightning surge analysis for offshore wind farm is investigated in this paper. The detailed model of electric equipment in the system is firstly developed, including the transmission tower, the power station, the wind turbine and so on. The supporting structure and the platform of offshore power station are then modelled based on method of partial element equivalent circuit. Considering three lightning strike scenarios, the overvoltages at critical nodes of the system are obtained, the mechanism for lightning surge characteristics within the farm are elucidated, the influence of submarine cable length on the transient overvoltage is discussed, and two surge arrester schemes have been proposed. The results indicate that the surge originating from onshore overhead line is the most serious situation. The submarine cable is beneficial to the lightning protection, and the incoming surge onshore decreases remarkably as the cable length increases. Surge arrester configuration needs to be adjusted based on the scale and the topology the system.

Simple Formula for Surge Impedance of Horizontal Grounding Conductor

Horizontal grounding conductor is often used to obtain low grounding resistance. Simulation results of voltages and currents in a circuit including a grounding system are sometimes different from measured results because the grounding resistance depends on temperature and water content. Lightning surge characteristics of a grounding conductor are important for lightning protection design. Simple formulas for the surge characteristics of the grounding conductor are useful for engineers to estimate the influence of parameters of grounding system on lightning overvoltages. This article describes measurement results of the surge characteristics of grounding conductors for various conductor lengths and terminal conditions. This article proposes simple formulas for surge impedance and propagation velocity of horizontal grounding conductor based on the measured results. A simple equivalent circuit of grounding conductor is described. The constants of the equivalent circuit are obtained using the proposed formulas. Simulation results of voltage on a grounding grid using the proposed formulas and the equivalent circuit of grounding conductor are compared with experimental results.

Lightning surge characteristics on inclined incoming line to substation based on reduced-scale model experiment

The lightning protection design of a substation is generally based on the surge overvoltage incoming to the substation, which is generated by the back-flashover across an insulator string of the transmission tower that is closest to the substation and struck by a lightning return stroke. In this case, surges propagate along non-horizontal or non-uniform lines such as the tower and the inclined lines incoming to the substation. Although the surge characteristics of a tower have been intensively studied as of today, those of inclined incoming lines to a substation have not yet been investigated. In this paper, experiments have been conducted using a reduced-scale model to clarify the surge characteristics of the conductor system that is composed of horizontal transmission line, two towers, inclined incoming line and a substation gantry. It turns out from the experiments that the potential (voltage) generated at the tower arm rises gradually, compared with the current injected in the tower top. Furthermore, it is found that the power line potential at the gantry is smaller than that that at the tower where the back-flashover occurs, while the opposite trend is obtained from a circuittheory- based simulation in which the inclined incoming line is represented by a horizontal line. The latter approximation has been usually employed in representing inclined incoming lines in lightning surge simulations using the Electromagnetic Transients Program (EMTP) or its alternatives. The fact that the power line potential at the gantry, evaluated by the present experiment, is smaller than the EMTPcomputed value would contribute to a more economical and rational design of a substation.

Lightning surge characteristics of an actual distribution line and validation of a distribution line model for lightning overvoltage studies

AbstractFor distribution lines in Japan, protection measures against lightning‐induced overvoltages have been taken and can be considered almost complete. The focus of lightning protection measures has moved to overvoltages due to direct lightning strokes. Studies of such overvoltages require simulations using the EMTP (Electro‐Magnetic Transients Program), and components of a distribution line must be modeled appropriately in the EMTP simulation environment. The authors have proposed an EMTP model of a distribution line in a separate paper. This paper consists of two parts. The first part presents surge characteristics of a distribution line obtained by measurement using an actual‐scale test distribution line. In particular, the result reveals noteworthy characteristics of the surge impedance of a reinforced concrete pole and the wavefront‐time dependence of insulator voltages. The second part presents a validation of the distribution line model previously proposed by the authors. The validation shows that the distribution line model accurately reproduces the measured voltage and current waveforms for various wavefront times of the injected currents. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(1): 1–10, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.21002

Analytical Study on Lightning Surge Characteristics of a Rail Track

AbstractThe development of the effective and economical protection measures is vital for the railway signaling systems because the lightning damages cause the disruption of the railway transportation systems. In general, the railway signaling systems are set up at a wayside and directly connected to the rails through cables. The lightning surges can invade the railway signaling systems via the cables and cause damages to the systems. Accordingly, clarifying the propagation characteristics of lightning surges along the rails is essential to develop the lightning protection measures in the railway signaling systems. We have carried out the field tests to examine both surge impedance and surge propagation velocity of the rails. This paper proposes a calculation model of the surge propagation characteristics along the rails. We measured the frequency‐dependent four‐terminal parameters of the rails to estimate the distributed parameter adopted in the calculation model. The results of surge impedance and surge propagation velocity calculated by the proposed model almost agree with the experimental results. Moreover, the proposed model can calculate the surge attenuation along the rails. This model is applicable to the development of lightning protection measures for the railway signaling systems. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Time- and Frequency-Dependent Lightning Surge Characteristics of Grounding Electrodes

Two phenomena dominantly influence the dynamic performance of grounding electrodes during lightning discharge: 1) the time-dependent nonlinear behavior related to soil ionization during high-current pulses and 2) the frequency-dependent electromagnetic (EM) effects related to fast rise-time current pulses. The first phenomenon improves the grounding performance, while the second might have the opposite effect of impairing the grounding characteristics. It is important to simultaneously analyze these opposing effects; however, modern approaches that take into account both phenomena are mostly based on circuit theory, which does not allow for accurate analysis of fast rise-time pulses. This paper proposes a procedure that combines a rigorous EM approach based on the method of moments with an approximation method for assessing soil ionization effects as recently recommended by the CIGRE and IEEE Working Groups. Based on this procedure, we derive a simple new formula for approximating the surge characteristics that include time-dependent ionization and frequency-dependent inductive effects. We verify the model and formula by comparing our data with published experimental results. We also describe a parametric analysis of the opposing ionization and inductive effects.

A Simulation Study of Lightning Surge Characteristics of a Distribution Line Using the FDTD Method

Recently, numerical electromagnetic field computation methods, which solve Maxwell's equations, have become a practical choice for the lightning surge analysis of power systems. Studies of lightning surge response of a transmission tower and lightning-induced voltages on a distribution line have already been carried out using the numerical electromagnetic field computation methods. However, a direct lightning stroke to a distribution line has not yet been studied.The authors have previously carried out pulse tests using a reduced-scale distribution line model which simulate the direct lightning stroke to a distribution line. In this paper, first, the pulse test results are simulated using the FDTD (Finite Difference Time Domain) method which is one of the numerical electromagnetic field computation methods, and comparisons are shown to validate the application of the FDTD method. Secondly, we present lightning surge characteristics of an actual-scale distribution line obtained by the FDTD method. The FDTD simulation takes into account the following items: (i) detailed structure of the distribution line; (ii) resistivity of the ground soil; (iii) propagation speed of the lightning return stroke.

Experimental and analytical studies on lightning surge characteristics of a buried bare wire

AbstractLightning surge analysis is very important from the viewpoint of insulation design of transmission lines and substations. Lightning surge analysis has many parameters, which include lightning surge characteristics of transmission towers, back flashover phenomena at an arcing horn, characteristics of footing resistance, effects of corona wave deformation, characteristics of electromagnetic fields caused by lightning, and other parameters. This paper describes experimental and analytical studies on lightning surge characteristics of a buried bare wire. The measurement of the lightning surge characteristics of the buried bare wire is carried out under various experimental conditions. The experimental parameters controlled in these experiments include earth resistance, length of the buried bare wire, and waveform of the injected current. The measured results are compared with analytical results based on the theoretical study by Sunde. A comparison of the measured results with the analytical results shows good agreement. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(3): 35– 41, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20532

Applications of Time-Domain Numerical Electromagnetic Code to Lightning Surge Analysis

Recently, applications of 3-D numerical electromagnetic analysis have been increasing either for lightning electromagnetic impulse (LEMP) studies or lightning surge analyses on transmission and distribution lines. This paper is mainly concerned with the use of time- and frequency-domain codes for electromagnetic analysis of lightning surges. The thin-wire in time-domain (TWTD) code and numerical electromagnetic code (NEC-2) in the frequency domain based on the method of moments are chosen for comparative studies. The accuracy of TWTD code in the analysis of lightning surge characteristics of a double-circuit transmission tower is first investigated by comparing the computed results with the measured results on a reduced-scale tower model, computed results by NEC-2 on a full-scale tower model, and those computed by electromagnetic transients program. In the latter part of the paper, a switch model is combined with the TWTD code, and its applicability in analyzing the lightning surge characteristics of a transmission tower equipped with a surge arrester or in analyzing lightning-induced voltage on an overhead line is demonstrated.

Experimental and analytical studies on lightning surge characteristics of ground mesh

AbstractLightning surge characteristics of a ground mesh have an influence on electromagnetic transient behaviors in low‐voltage and control circuits. This paper describes experimental and analytical studies on lightning surge characteristics of a ground mesh. The experimental studies are carried out under various conditions. The experimental parameters considered in this measurement include earth resistances, current injection points, and injection current waveforms. These measured results are compared with calculated results based on the theoretical studies by Sunde. A comparison of the measured results with the calculated results shows good agreement. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 160(4): 16– 23, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20559

Experimental and Analytical Studies on Lightning Surge Characteristics of Ground Mesh

Lightning surge characteristics of a ground mesh have influence on electromagnetic transient behaviors in low voltage and control circuits. This paper describes experimental and analytical studies on lightning surge characteristics of a ground mesh. The experimental studies are carried out under various conditions. The experimental parameters considering in this measurement include earth resistances, current injection points and injection current waveforms. These measured results are compared with calculated results based on the theoretical studies by Sunde. A comparison of the measured results with the calculated results shows good agreement.

Experimental and Analytical Studies on Lightning Surge Characteristics of a Buried Bare Wire

Lightning surge analysis is very important from the viewpoint of insulation design of transmission lines and substations. Lightning surge analysis has many parameters, which include lightning surge characteristics of transmission towers, back flashover phenomena at an arcing horn, characteristics of footing resistance, effects of corona wave deformation, characteristics of electromagnetic fields caused by lightning, and other parameters. This paper describes experimental and analytical studies on lightning surge characteristics of a buried bare wire. The measurement of the lightning surge characteristics of the buried bare wire is carried out under various experimental conditions. The experimental parameters controlled in these experiments include earth resistance, length of the buried bare wire and waveform of the injected current. The measured results are compared with analytical results based on the theoretical study by Sunde. A comparison of the measured results with the analytical results shows good agreement.

Numerical electromagnetic field analysis on lightning surge response of tower with shield wire

Lightning surge characteristics of a transmission line comprising a tower, a shield wire and phase conductors are studied with the help of NEC-2. A tower struck by a lightning stroke behaves as an antenna until a traveling wave makes several roundtrips in the tower. During this interval, the tower footing impedance appears to be higher than the footing resistance, and the coupling coefficient between a shield wire and a phase conductor is much lower than that in the TEM mode. These affect the estimation of insulator voltages of transmission towers subject to lightning currents having short rise times. On the basis of these findings, the parameters in the multistory tower model, which has been used widely in EMTP multi-conductor analyzes, are newly proposed.

実規模送電線の雷サージ特性

実規模送電線の雷サージ特性

数値電磁界解析手法による送電線サージ特性の検討

数値電磁界解析手法による送電線サージ特性の検討

77kV変電所で観測される侵入雷サージの特徴

77kV変電所で観測される侵入雷サージの特徴

Lightning surge test generator for telecommunication equipment

AbstractLightning surge which is induced on a telecommunication cable may damage telecommunication equipment. This paper proposes a design method for a lightning surge generator which can accurately predict reliability for the lightning surges in telecommunication equipment and the quality of the lightning surge generator developed based on this method is described.First, the characteristics of the lightning surge which is fed to the equipment are determined from such factors as the lightning surge inducing mechanism. Next, the testing surge waveform design method is determined in which evaluations of the lightning surge proof of equipment by the peak voltage, steepness (peak voltage/ front time) and energy of the lightning surge can be performed in one surge test. The testing surge waveform then is determined based on this design method.A method is described for realizing the lightning surge characteristics and the testing surge waveform using a basic impulse voltage generator circuit which consists of an LRC circuit with few circuit elements. Experimental results demonstrate that the developed lightning surge generator based on the proposed designing method can predict the malfunction rate accurately.It is shown also that it is highly practical because its size and cost are about one‐tenth that of a conventional testing device.

実雷撃による奥獅子吼試験送電線雷サージ特性観測結果

実雷撃による奥獅子吼試験送電線雷サージ特性観測結果

Lightning research advances with digital surge recordings

Some of the results of EPRI research project RP 2542-1, Characteristics of Lightning Surges on Distribution Lines, are discussed. The project utilized a large number of microcontroller-operated lightning transient recorders (LTRs) to perform an assessment of lightning surge characteristics occurring at metal oxide distribution arresters installed on 12.47 and 13.2 kV power distribution systems. The impact of digital recording techniques, microprocessor-controlled instrumentation, software that can perform automatic data sorting, and waveform analysis on lightning surge measurement and analysis capabilities is highlighted. Measurements were performed for two years; the first year arrester discharge voltages were measured, and the second year arrester discharge currents were measured. The LTR and its sensor were also evaluated during actual lightning conditions. The LTR and the specially designing voltage and current sensing arrester developed and used in conjunction with it are described, and the wave shape analysis procedure and results are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Lightning-caused distribution circuit breaker operations

As a part of EPRI Research Project 2542-1, Characteristics of Lightning Surges on Distribution Lines, a coincident lightning events detector (CLED) was developed, tested, and installed in a test area on the Florida Power Company distribution system in St. Petersburg, Florida. The CLED provided the data to determine the number of lightning-caused circuit breaker operations for the first time. During the 3-year recording period, a total of 546 faults causing circuit breaker operations occurred on the seven circuits in the test area. Of these faults, 415 (or 76%) were temporary faults. A lightning strike was coincident with 42% of the temporary faults. Improper operation of line fuses was traced to the absence of lightning arresters at line fuse locations.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>