Lightning Surge Analysis Research Articles

Grounding resistance model considering propagation time between grounding electrodes

The velocity of electric field in the soil is sufficiently lower than that in the air. Conventional grounding resistance models based on an electric circuit theory ignore the propagation time between grounding electrodes (GEs). If the GEs are connected using an aerial lead conductor, the propagation time along the lead conductor is apparently different from that along a grounding conductor (GC) in the soil. The propagation time of mutual grounding resistance between GEs should be considered in accurate lightning surge analysis. This paper proposes a simulation model of the mutual grounding resistance considering the propagation time between GEs.

Incorporating the LEMP Impact on Lightning Surge Analysis of Transmission Lines in EMT Simulators

Incorporating the LEMP Impact on Lightning Surge Analysis of Transmission Lines in EMT Simulators

A circuit model of electrical wiring nearby building structure for lightning surge analysis

AbstractA model expressing beams, pillars, and electrical wiring in a building for lightning surge simulation by circuit analysis method is proposed in this paper. The proposed model expresses the self‐surge impedance of the electrical wiring as a function of the distance between conductors and the radius of the electrical wiring. The mutual impedance is expressed by the distance between the surfaces of a structure and a nearby wire instead of the distance between the conductor centers. In the case of two conductors having far different radii in proximity, the distribution of electromagnetic fields around the two conductors is similar in horizontal and vertical arrangements. Thus, the electrical wiring nearby pillars can be treated as a horizontal conductor. The circuit analysis results show that the voltage difference generated between the structure and the electrical wiring is calculated more precisely by the proposed model than by the conventional model.

Direct Lightning Surge Analysis of Distribution Lines Considering LEMPs From Lightning Channel and Struck Pole in EMT Simulation

Direct Lightning Surge Analysis of Distribution Lines Considering LEMPs From Lightning Channel and Struck Pole in EMT Simulation

Lightning surge analysis for hybrid wind turbine-photovoltaic-battery energy storage system

Lightning surge analysis for hybrid wind turbine-photovoltaic-battery energy storage system

Influence of a shield wire flashover on the indirect lightning performance assessment of distribution lines

This paper presents a new aspect of shield wire (SW) modeling for assessing the indirect lightning performance of overhead medium-voltage distribution lines: a flashover (FO) between an SW and the reinforcing bars of a distribution pole or a crossarm (SWFO). In general, an SW is periodically grounded approximately every four to ten poles and not grounded at the other poles. However, owing to lightning-induced overvoltages, the voltage difference between the SW and the distribution pole may even exceed 100 kV, and the SWFO can occur. In this paper, we evaluate the effect of the SWFO on the number of FO occurrences of phase-conductor insulators by the Monte Carlo method using a 2D finite-difference time-domain-based indirect lightning surge analysis program. The effect of the SWFO is more significant in lines with high soil resistivity (a soil resistivity of 1000 Ωm was assumed) regardless of the installation of surge arresters: the total number of FO occurrences markedly differs by up to 50% between cases in which the SWFO is considered and not considered. The analysis presented in this paper will assist the formulation of lightning protection measures particularly, in regions with high-resistivity soils.

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.

Influence of configuration of power distribution lines on failure probability of surge arresters

In Japan, many surge arresters have been installed on 6.6 kV overhead distribution lines for reducing lightning overvoltages. The increase of surge arresters has resulted in a remarkable decrease of lightning outages of distribution lines caused by insulator flashovers. In contrast, several surge arresters have been damaged by direct lightning strikes to distribution lines. Studies of countermeasures for the failure of surge arresters are generally carried out by lightning surge analysis using the Electro Magnetic Transients Program (EMTP). In the previous studies, a simple model of a straight line is used, however, branch lines and termination points also exist in the actual distribution lines. In this paper, we present the influence of configuration of distribution lines on the failure probability of surge arresters obtained by the lightning surge analysis.

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.

Lightning Surge Analysis for Overhead Lines Considering Corona Effect

Corona discharge characteristics are measured in a corona cage. The difference is found between the q–u curves under double exponential and damped oscillation surges. The behavior of the minor loops is revealed for the q–u curves under positive and negative damped oscillation surges. An extended improvement is made on the traditional approach for modeling of the q–u curves under damped oscillation surges. The extended approach has the capability of describing the complicated trajectory feature of the minor loops. On the basis of the extended approach, an efficient method is proposed for performing lightning surge analysis of overhead lines considering the corona effect. In the proposed method, an overhead line with corona is divided into a certain number of line segments. Each segment is converted into a circuit unit consisting of a non-linear branch and a linear circuit. With these circuit units connected in sequence, a complete equivalent circuit is constructed for the overhead line with corona. The transient responses can be obtained from the solution to the equivalent circuit. Then, the calculated results are compared with the field test results on a test overhead line.

Lightning Surge Analysis of Transmission Line Towers With a Hybrid FDTD-PEEC Method

This paper addresses lightning surges on the transmission systems with a new hybrid method, using a 1D FDTD model for the transmission line and a PEEC model for the tower and lightning channel. Compared with other circuit-based models, mutual coupling between the lightning channel and other parts in the system can be fully considered. This hybrid method has been validated numerically and experimentally, and good agreements are observed. This method then is applied to analyze the lightning surges on a 500 kV double-circuit transmission line system. It is found that the lightning channel has a significant impact on the surge response of the tower struck. Ignoring the coupling from the channel to the tower will weaken the hazard of lightning strikes. However, the influence of its coupling to the transmission line is not critical. The choice of interfacing points between these two models is then suggested. Furthermore, the influence of the tower footing is inves tigated. It is found that the insulator voltage is made of inductive and resistive components. The inductive component becomes dominant in the case of high soil conductivity and low grounding resistance. The voltage generally increases with decreasing soil conductivity and tends to decay slowly with time.

Circuit Model of Vertical Double-Circuit Transmission Tower and Line for Lightning Surge Analysis Considering TEM-mode Formation

The electromagnetic fields, which are produced by lightning currents flowing into a transmission tower and into overhead ground wires, spherically expand with time, and propagate as non-transverse electromagnetic (TEM) waves at least within the round trip time of the traveling wave along the tower. In this paper, a distributed-parameter line model of a vertical double-circuit transmission tower with an overhead line struck by lightning is composed considering the non-TEM characteristics. The surge impedances of the tower, ground wires, and phase conductors increase with time and reach their TEM-mode or steady state values with time constants determined from the configuration. In addition, the significant wave attenuation along the tower is included in the circuit model according to the propagation characteristic determined by the tower configuration. The virtual inductive grounding impedance or damping circuits for approximately representing the wave attenuation is no longer needed. The proposed model is applied to four types of transmission towers. Waveforms of voltages across insulator strings computed by the finite-difference time-domain method, which are regarded as the reference, are well reproduced by the proposed model. Computation efficiency is drastically improved by the proposed model comparing to the numerical electromagnetic field analysis.

Lightning Surge Analysis of a Transmission Line Tower With an XLPE Power Cable and Metallic Cleats Using the FDTD Method

A direct lightning strike to a transmission line tower may cause overvoltages and insulation failures, and to avoid unexpected insulation failures and protect power equipment, it is necessary to install effective lightning protection measures. To design effective countermeasures, the prediction of lightning surge phenomena is required. The finite-difference time-domain (FDTD) method, one of the full-wave numerical approaches, which do not require the assumption of the transversal electromagnetic mode, has been an effective tool for predicting electromagnetic transient phenomena in 3-D structures, such as transmission line towers. In this article, using a technique for representing coaxial cables in the FDTD method, we simulate a reduced-scale model of a transmission line tower with a power cable, calculate the surge phenomena in the tower model when a surge current is injected into the top of the tower, and compare the FDTD results with the measured results for validation. Furthermore, we propose a technique for simulating the influence of using metallic cleats to fix a power cable to a transmission line tower for FDTD simulations in a 3-D arrangement, and we calculate surge phenomena in practical cross-linked polyethylene power cables placed over a ground plane and installed in a real-scale 77 kV transmission line tower. The FDTD results are validated through the comparison with measured results obtained in a previous study.

Application of the FDTD-based simulation code VSTL REV to the lightning surge analysis of a nuclear power plant

The installation of effective lightning protection is necessary to protect power equipment and sensitive electronic devices and guarantee human safety in nuclear power plants. To evaluate the effectiveness of countermeasures against lightning, it is necessary to predict lightning surge phenomena. Recently, the finite-difference time-domain (FDTD) method, which is one of the full-wave numerical approaches, has been applied for analyzing electromagnetic transient phenomena in three-dimensional structures such as lightning protection systems and buildings or grounding structures such grounding grids. In this study, we model buildings and grounding structures of a nuclear power plant using the FDTD-based surge simulation code VSTL REV, and we study the effect of soil resistivities on the step voltages around the reactor building and the voltages induced on grounding buses drawn into an auxiliary building and the metal sheaths of coaxial cables in the case of a direct lightning strike to the nuclear power plant.

Lightning Propagation Analysis on Telecommunication Towers Above the Perfect Ground Using Full-Wave Time Domain PEEC Method

Lightning surge propagation on telecommunication towers is essential to lightning protection design. Analysis of very fast surges in a telecommunication tower requires a full-wave solution of Maxwell's equations. This paper proposes a full-wave time domain partial element equivalent circuit (PEEC) method considering the effect of ground to evaluate the surge currents and voltages on vertical structures. The PEEC of the formulation is provided by using the method of image. This method can take into account the attenuation of the lighting surges, and has the potential to be implemented as a new type of solution for general lightning surge analysis. The proposed method is validated numerically with the finite-difference time domain method, and is used to analyze the surge propagation on cables mounted on two typical grounded telecommunication towers. The simulation shows that both the location of cable installations and the type of towers have a significant influence on the lightning protection performance.

Frequency and Current-Dependent Grounding Resistance Model for Lightning Surge Analysis

The frequency dependence as well as the current dependence of grounding resistance affects lightning overvoltages in electric power system. This paper proposes an equivalent circuit to simulate the frequency dependence of soil resistivity and permittivity. Constants of the equivalent circuit are determined based on empirical formulas for the frequency dependence of the soil parameters proposed by Alipio and Visacro. The equivalent circuit is represented in time domain. Therefore, the equivalent circuit is applicable to the calculation of the current dependence of the grounding resistance. An influence of the frequency dependence of the soil resistivity and permittivity on the current dependence of the grounding resistance is discussed by the use of the equivalent circuit. This paper proposes a modified CIGRE model to calculate the current dependence of the grounding resistance. The equivalent circuit is very convenient and useful for engineers to carry out lightning surge analysis.

A Study on Overvoltages in Windfarm Caused by Direct Lightning Stroke

Wind turbine generators in a windfarm are connected by underground cables. Lightning sometimes strikes a nacelle or a blade. Lightning overvoltages due to a direct lightning strike to the system cause damages in the underground cable. Many parameters should be investigated to establish a rational lightning protection design for wind power generation system. Numerical simulation is a useful method to discuss the influence of the parameters on the lightning overvoltages. This paper uses an Electro-Magnetic Transients Program for the lightning surge analysis. This paper discusses the influence of grounding method of metallic sheath of the cable and grounding resistance on the lightning overvoltages for the direct lightning strike to the generation system.

Study on Model of Lightning Surge Analysis for Railway Telecommunication Systems

Study on Model of Lightning Surge Analysis for Railway Telecommunication Systems

Lightning Surge Analysis on a Large Scale Grid-Connected Solar Photovoltaic System

Solar photovoltaic (PV) farms currently play a vital role in the generation of electrical power in different countries, such as Malaysia, which is moving toward the use of renewable energy. Malaysia is one of the countries with abundant sunlight and thus can use solar PV farms as alternative sources for electricity generation. However, lightning strikes frequently occur in the country. Being installed in open and flat areas, solar PV farms, especially their electronic components, are at great risk of damage caused by lightning. In this paper, the effects of lightning currents with different peak currents and waveshapes on grid-connected solar PV farms were determined to approximate the level of transient effect that can damage solar PV modules, inverters and transformers. Depending on the location of the solar PV farm, engineer can obtain information on the peak current and median current of the site from the lightning location system (LLS) and utilise the results obtained in this study to appropriately assign an SPD to protect the solar panel, inverter and the main panel that connected to the grid. Therefore, the simulation results serve as the basis for controlling the effects of lightning strikes on electrical equipment and power grids where it provides proper justification on the ‘where to be installed’ and ‘what is the rating’ of the SPD. This judgment and decision will surely reduce the expensive cost of repair and replacement of electrical equipment damages due to the lightning.

A Lightning Surge Analysis Example and Lightning Protection of High Voltage Power Receiving Equipment

A Lightning Surge Analysis Example and Lightning Protection of High Voltage Power Receiving Equipment