Lightning Surge Response Research Articles

Experimental and Analytical Studies on Lightning Surge Response of the Quadruple-Circuit Transmission Line

The compact design of a 500 kV quadruple-circuit transmission line can effectively reduce the line corridor area, but the height of the tower also increases, increasing the probability of suffering a lightning strike. The 500 kV quadruple-circuit transmission lines carry more energy, and because of this, lightning strikes that cause power line trips are more likely to result in large-scale power outages. Therefore, it is necessary to make an accurate assessment of the lightning performance of 500 kV quadruple-circuit transmission lines. First, simulated lightning-striking experiments were carried out on a scaled 500 kV quadruple-circuit transmission line in the laboratory, where transient voltages and currents were measured. Second, a numerical model was established with the Finite-Difference Time Domain (FDTD) method, which was then verified with the experimental results. Third, lightning surge responses of a 500 kV quadruple-circuit transmission line under near-real facility conditions are estimated with the verified FDTD model. In the simulations, influencing factors, such as the rise time of injecting current, the velocity of return-stroke current and the terrains, were taken into consideration, but not in previous lightning surge analysis with the Electromagnetic Transients Program (EMTP). Results show that insulator voltages on the same tower cross-arm are nearly identical, although the length of the cross-arm is large enough. Furthermore, it is found that the rise time and the lightning current velocity have great effects on the lightning surge response, and the terrains are less impactful but not negligible. Therefore, these factors should be considered carefully where higher accuracy lightning protection design is necessary.

Lightning Surge Response of a Transmission Tower with Overhead Lines Analyzed by TEM-delay Model

Lightning Surge Response of a Transmission Tower with Overhead Lines Analyzed by TEM-delay Model

Lightning surge response of a double-circuit transmission tower with incoming lines to a substation through FDTD simulation

A transmission tower model that can reproduce the lightning surge response is important for analyzing the lightning surge. In developing such tower model, however, studies have been conducted using a stand-alone tower or a condition where the tower and transmission lines are orthogonally crossed. This could be attributable to the difficulty in handling a complex layout in conventional experiments and theoretical studies. The present paper verifies the accuracy of the FDTD analysis, based on a comparison with the experimental results. Subsequently, it studies the influence of the layout and the inclined angle of the incoming lines to the substation on the surge response of the tower under near-real facility conditions via electromagnetic field analysis using the FDTD method. As a result, the voltage of the insulator strings peaked with a zero-degree incoming angle and it declined with increasing angle, namely by about 20% when the inclined angle was 37.5 degrees. Finally, the current waveform was analyzed in addition to the voltage characteristics and the generation mechanism of the line voltage was explained.

Lightning surge response of a double-circuit transmission tower with incoming lines to a substation through FDTD simulation

A transmission tower model that can reproduce the lightning surge response is important for analyzing the lightning surge. In developing such tower model, however, studies have been conducted using a stand-alone tower or a condition where the tower and transmission lines are orthogonally crossed. This could be attributable to the difficulty in handling a complex layout in conventional experiments and theoretical studies. The present paper verifies the accuracy of the FDTD analysis, based on a comparison with the experimental results. Subsequently, it studies the influence of the layout and the inclined angle of the incoming lines to the substation on the surge response of the tower under near-real facility conditions via electromagnetic field analysis using the FDTD method. As a result, the voltage of the insulator strings peaked with a zero-degree incoming angle and it declined with increasing angle, namely by about 20% when the inclined angle was 37.5 degrees. Finally, the current waveform was analyzed in addition to the voltage characteristics and the generation mechanism of the line voltage was explained.

A simulation method for lightning surge response of switching power

In order to meet the need of protection design for lighting surge, a prediction method of lightning electromagnetic pulse (LEMP) response which is based on system identification is presented. Experiments of switching power's surge injection were conducted, and the input and output data were sampled, de-noised and de-trended. In addition, the model of energy coupling transfer function was obtained by system identification method. Simulation results show that the system identification method can predict the surge response of linear circuit well. The method proposed in the paper provided a convenient and effective technology for simulation of lightning effect.

Experimental Evaluation of UHV Gantry Tower Model for Lightning Surge Analysis

An experimental investigation was performed on a UHV gantry tower model for the EMTP calculation of lightning overvoltage at substation. The various lightning surge response characteristics were measured on a 1/10 scale UHV gantry tower. We present the comparison between measured and calculated voltage waveforms at various point of gantry tower. It showed that measured waveforms were not reproduced in the conventional EMTP model. It was estimated that it did not take horizontal element into consideration. Since then, the model was improved in new model, which had a horizontal element. Measured waveforms were reproduced by the improved EMTP model. Surge impedance of the improved model is as the next. Vertical element is 220-ohm, horizontal element is 140-ohm.

Electromagnetic Analysis of Interconnected Groundings at Wind Farm

Interconnection of the grounding system of wind turbines reduces steady-state grounding resistance, however, the transient behavior during a lightning strike to an interconnected wind turbine grounding system remains to be discussed. This paper investigates the influence of interconnection on the lightning surge response of wind turbine grounding system. Two different numerical methods, Numerical Electromagnetics Code (NEC-4) based on Method of Moments (MoM), and Virtual Surge Test Lab (VSTL) based on Finite Difference Time Domain (FDTD) method, are used for lightning surge analysis of wind turbine grounding systems. Comparison of results using NEC-4 and VSTL are made to clarify the usefulness of these methods for transient analysis of a large grounding system. The influence of soil parameters, front time of injected current, and the type of a conductor employed for interconnection, on the response of interconnected wind turbine grounding is discussed.

Experimental and Analytical Studies on Lightning Surge Response of 500-kV Transmission Tower

This paper presents experimental and analytical studies on the lightning surge response of a 500-kV transmission tower without overhead lines. A number of experimental studies on the lightning surge response of transmission towers have been carried out. However, in these studies, the influence of the current injection angle was ignored. In this paper, an experimental investigation is conducted to assess the influences of the angle and direction of current injection. It is clearly shown that the lightning surge response of the tower depends on the angle and direction of current injection. These experimental results are compared with results calculated using numerical electromagnetic (EM)-field analysis. These calculated results agree with the experimental results. This suggests that numerical EM-field analysis can be employed for evaluating the surge response of a tower. Based on this, the surge response of a tower under a vertical lightning stroke is estimated. It is shown that the surge response under vertical current injection is approximately 30% higher than that under horizontal current injection. It is also shown that the angle and direction of the return stroke are important factors in determining the lightning surge response of a transmission tower.

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 Study on Lightning Surge Response of 500-kV Transmission Tower With Overhead Lines

This paper presents the measurement of the lightning surge response of a 500-kV transmission tower with overhead lines including ground wires and phase wires. A number of experimental studies on the lightning surge response of transmission towers have been carried out using freestanding structures such as scale models or actual transmission towers. However, these experiments have ignored the effects of transient electromagnetic coupling among the injection current, the overhead lines, and the tower. This paper reports a new method of measurement considering the arrangement of an actual tower and overhead lines. It is clearly shown that the measured voltage waveform across insulator strings at each crossarm depends on the direction of the injection current. Moreover, the measured current value flowing into the ground wires varies with the direction of the injection current. These results predict that the surge response of a transmission tower depends on the direction of the return stroke current. This is important for the modeling of towers with overhead lines and the estimation of the lightning performance of transmission systems under a lightning stroke.

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.

Transient analysis of nonuniform lossy transmission lines with frequency dependent parameters

An s-domain method for transient analysis of lossy, frequency dependent nonuniform transmission lines having parameters arbitrary varying with space is presented. Nonuniform line is divided into adequate number of sections which are then assumed uniform. The terminal equation for the nonuniform line is calculated by using the terminal equations of the uniform line sections. By using the boundary conditions, total response in s-domain is obtained. Fast inverse Laplace transform is used for frequency to time domain conversion. In one of the examples, the step response of an open ended nonuniform line is obtained and the results are compared with those obtained by lattice-diagram technique. The effect of number of sections is investigated and it is concluded that for sufficiently large number of sections, the results approach to the analytical solutions which can be obtained only for very special nonuniform lines. In the second example, the method is applied for the calculation of transmission tower lightning surge response.

95/01554 Modified fourier transform lighting surge analysis of an overhead line-underground coaxial (CV) cable system Part II. System lightning surge response

95/01554 Modified fourier transform lighting surge analysis of an overhead line-underground coaxial (CV) cable system Part II. System lightning surge response

Experimental evaluation of a UHV tower model for lightning surge analysis

An experimental investigation was performed on a UHV tower model for the EMTP multiconductor calculation of lightning overvoltage at substations associated with back-flashover at an adjacent transmission tower. The various lightning surge response characteristics were measured on an actual UHV tower, and parameters of a multistory transmission tower model that can reproduce voltages across the insulator strings, voltages of the crossarms, and voltages of the power lines were determined. A value of 120 /spl Omega/ was determined as the surge impedance at each section of the multistory tower model, which closely agreed with the tower surge impedance measured for the UHV tower alone.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Modified Fourier transform lightning surge analysis of an overhead line-underground coaxial (CV) cable system Part II. System lightning surge response

The lightning surge analysis of an overhead line-underground CV cable transmission system has been carried out using the modified Fourier transform with a multiconductor representation. The frequency dependence of the transmission system components such as the overhead transmission line, underground cable and towers has been analyzed. A digital simulation based on this analysis has been developed and applied to a 77 kV three-phase single-circuit system. The results for a direct hit by a lightning stroke at the riser pole tower top show that the overvoltages at the riser pole increase with increase in the tower footing resistance and that the phase conductor overvoltages are greatly affected by the CV cable. The cable open-tie overvoltages decrease with increase in the cable length.

Tower modelling for lightning surge analysis using Electro-Magnetic Transients Program

For economical insulation co-ordination in transmission and substation equipment, it is necessary to accurately predict the lightning surge overvoltage that occurs in an electric power system. The lightning surge response of transmission towers is one of the main factors that influences the magnitude and the waveshape of the surge arriving at a substation. The paper presents a tower model, based on a finite-difference transmission-line model, that can be used with EMTP. Computation results obtained, for a typical double-circuit 500 kV tower, are in good agreement with field test measurements.

Lightning surge response of ground electrodes

Lightning surge currents cause nonlinear ionization and transient propagation when injected into ground electrodes. The low-current footing resistance is modeled in terms of electrode length and surface area. The ionization process follows a similarity method originated by A.V. Korsuncev (1958). Calculation and experiment show the surge response of a conducting ground plane. Electrode shape, soil type, ionization and propagation are then combined to provide a comprehensive model of tower footings for use in predicting the lightning outage rates of overhead transmission lines. The model is compared with previous experimental and analytical work and is shown to provide a reasonable match.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Lightning Surge Response of Transmission Towers

Lightning Surge Response of Transmission Towers