Lightning Protection Performance Research Articles

Tower impulse grounding resistance measurement based on multiple frequency impedance

AbstractTower impulse grounding resistance is important for judging the lightning protection performance of transmission lines. Therefore, it is significant to accurately measure the tower impulse grounding resistance. Existing measurement methods mainly contain the real‐type test method and the impulse coefficient method. However, the real‐type test method requires heavy and complex excitation and measuring equipment, which is difficult to be used in a practical environment. The impulse coefficient method adopts the empirical equations, which could have large measurement errors in different environments. To solve the above problems, this paper studies a novel impulse grounding resistance measurement method (IGRMM) based on multiple frequency impedance. Spectrum characteristics of typical lightning currents and the calculation method of impulse grounding resistance of grounding electrodes are studied, the IGRMM is proposed. Finally, a case study and on‐site tests are carried out. The results show that the proposed IGRMM can accurately obtain the impulse grounding resistance by measuring grounding impedance at a few frequency points, which helps accurate and convenient evaluation of impulse grounding performance in practical environments and lightning protection performance of the power transmission systems.

Study on the Lightning Protection Performance for a 110 kV Non-Shield-Wired Overhead Line with Anti-Thunder and Anti-Icing Composite Insulators

Due to micro landforms and climate, the 110 kV transmission lines crossing the mountain areas are exposed to severe icing conditions for both their high voltage (HV) conductors and shield wires during the winter. Ice accumulation on the shield wire causes excessive sag, which leads to a reduced clearance between earth and HV wires, and could eventually result in tripping of the line due to phase-to-ground flashover. Due to the lack of effective de-icing techniques for the shield wires, removing them completely from the existing overhead line (OHL) structure becomes a reasonable solution to prevent icing accidents. Nevertheless, the risk of exposure to lightning strikes increased significantly after the shield wires were removed. In order to cope with this, the anti-thunder and anti-icing composite insulator (AACI) is installed on the OHLs. In this article, the 110 kV transmission line without shield wire is considered. The shielding failure after installation of the AACIs is studied using the lightning strike simulation models established in the ATP software. The lightning stroke flashover tests are carried out to examine the shielding failures on various designs for the AACIs. Assuming the tower’s earth resistance is 30 Ω, the LWL of back flashover and direct flashover are 630.88 kA and 261.33 kA, respectively, after the installation of AACIs on an unearthed OHL. Due to the unique mechanism of the AACI, the operational voltage level and the height of the pylon have a neglectable influence on its lightning withstand level (LWL). When the length of the parallel protective gap increases from 450 mm to 550 mm, the lightning trip-out rate decreases from 0.104 times/100 km·a to 0.014 times/100 km·a, and the drop rate reaches 86.5%. Therefore, increasing the gap distance for the AACI to provide additional clearance is proven to be an effective method to reduce the shielding failure rates for non-shield-wired OHLs.

Analysis of shielding failure of transmission line based on pilot model

Since the main way of power transmission in China is overhead line transmission, some overhead lines are in a harsh outdoor environment. Among them, the bypass attack is more serious. Shielding Failure is a severe form of lightning damage. Based on the situation, this article studies the lightning shielding phenomenon of transmission lines. This article uses the pilot development model to simulate the lightning strike process, analyzes the different target objects of the lightning strike, and elaborates and calculates the lightning shielding trip rate. In addition, by changing the protection angle, the height of the tower, the ground inclination of the area where the line is located, and the number of lines, the impact of these four factors on the lightning shielding trip rate is discussed. According to the influencing factors, measures to strengthen the lightning protection performance of the line are proposed.

Algorithm for Solving Trip‐Out Rate Due to Shielding Failure of Bent Transmission Line

Accurate assessment of lightning protection performance of extra high voltage transmission lines is important for transmission line design and different lightning protection. Based on the electro‐geometrical model, this paper introduces the angle influence factor, and presents an algorithm for shielding failure trip‐out rate of angle tower, and the existing algorithm is expanded. By establishing the three‐dimensional geometric model of the angle tower, the electrical geometric relations of conductors and ground wires on both sides are analyzed, respectively, and the projection area algorithm for shielding failure is modified. To further verify the application value of the calculation algorithm, the change of the shielding failure trip‐out rate of the typical angle tower with the bending angle of transmission line and the tower height in a 500 kV transmission line is analyzed. The analysis results show that the trip‐out rate of the outside corner is higher than that of the inside one, and with the increase of the angle and the height of the tower, the trip‐out rate shows an upward trend. When the tension tower height is 71.5 m and the angle increases from 0° to 80°, the outside shielding failure trip‐out rate increased by 10.9% and the inside decreased by 9.3%. Compared with the classical electro‐geometrical model calculation, the difference of trip‐out rate is 4.3% when the bending angle is 80°. When the tangent tower height is 70 m and the angle increases from 0° to 40°, the shielding failure trip‐out rate on the outside increased by 5.9% while the inside decreased by 6.2%. The research results provide a simple algorithm for solving bending transmission line and give some reference for lightning protection design of EHV transmission lines. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Lightning protection performance of quadruple-circuit 500 kV transmission lines on the same tower with composite cross arm

In recent years, composite materials cross-arm (CMCA) towers have been gradually used in 10 kV, 35 kV or other transmission lines with lower voltage level in China. However, it is rarely used in higher voltage level transmission lines, especially in multi circuit lines on the same tower. Because of its higher height, we should pay more attention to the lightning protection performance of high voltage level multi circuit lines on the same tower. In this work, the simulation and calculation analysis of Lightning stroke model of quadruple-circuit 500 kV transmission line is done to compare CMCA tower with steel tower. The research shows that the tolerance lightning level of CMCA tower is superior to conventional steel tower, The lightning withstand level of single circuit flashover is 45% higher than that of steel tower and the minimum shielding failure lightning withstand level is 47% higher than that of steel tower. The data can provide the theoretical basis for the construction and optimization design of high voltage CMCA tower.

Lightning Shielding Failure Analysis of High Voltage Transmission Lines Based on Leading Development Model

Lightning strikes are one of the important causes of line faults. With the increase of voltage levels, the proportion of short-circuit trip accidents caused by shielding strikes is increasing. Therefore, accurate evaluation of the line’s shielding lightning resistance is important for power systems. Its safe and stable operation is of great significance. In this paper, based on the derivation of the pilot development model (LPM) for evaluating the shielding characteristics of the line, taking the 500kV single-circuit line network of the East China Power Grid as the research object, the lightning shielding trip rate and related influencing factors are analyzed and calculated, and the methods for enhancing the lightning protection performance are given. Measures.

Effective Grounding of the Photovoltaic Power Plant Protected by Lightning Rods

This article discusses the lightning protection performance of a grounding grid for photovoltaic (PV) systems protected by independent lightning rods. Several grounding grid configurations are investigated, and the transferred voltages between the dc cables and supporting structures at different points in the PV system are evaluated using the finite difference time domain (FDTD) method. In the PV system without a dedicated grounding grid for supporting structures, the transferred voltage is very high, and is even worse if the soil resistivity is high. Installing a dedicated grounding grid, which is very costly in a large PV power plant, can reduce the amplitude of the transferred voltage and eliminate the residual voltage effectively. It is found that the arrangement using a bonding network is superior to other grounding improvement approaches in lightning protection. More importantly, the proposed approach is simple to implement and cost-effective. With the bonding network, the soil with high soil resistivity will not lead to severe overvoltage in the system. It is highly recommended to be adopted in the PV power plant protected by independent lightning rods.

Electric Arc Recoil–A Novel Method for Reducing Lightning Strike Potential Difference for Transmission Line

Increasing arc pressure by tens of times with fine pouring tube, a positive shock wave by the pouring arc entering the closed space of the thin tube (electric arc recoil wave). The pressure of electric arc recoil wave is 8 to 23 times than that of the arc tube pouring wave. Since the recoil wave has more pressure than the arc tube pouring wave, and their directions are opposite, the tube poring arc is driven away from the tube channel by the recoil wave. The arc completely emptying and a large scale truncation to the electric arc are formed. Therefore, the truncation arc interrupts the lightning current, and recombusts to form a new tube pouring wave and backwash wave. The arc truncation and recombustion are caused by arc tube pouring and electric arc recoil alternately, and forming the intermittent lightning discharge, a large decrease in the amplitude of lightning current, steepness and discharge time. The results show that the amplitude of lightning current can reduce from 67.14 kA to 35.1 kA, and the lightning current steepness can decrease 77.3%. This attenuation method of lightning current amplitude could significantly reduce the lightning current flowing into the ground, the induced overvoltage and the ohm potential difference. Additionally, the problem of lightning strike step voltage in high soil specific resistivity areas and electromagnetic induced overvoltage can be solved by the method in this paper. The probability of original fault is reduced, and the operation reliability is enhanced. The method can lower the cost of ground network and improve the lightning protection performance.

Overview of lightning location systems

Lightning location systems provide valuable and vital data for study of lightning on the earth. Developed nations already built not only one but aslo many lightning location networks in their territories in order to collect highly reliable national dataset of lightning. Moreover, these national lightning detection systems are linked together to increase both the collecting range and the accuracy. However, in Vietnam, lightning location systems are not payed enough attention on. Therefore, the authors attempt to provide an overiew of lightning location systems and their importance to the field of lightning protection in this research. The paper provides an overview of the operating principles of popular lightning location systems in the world. Besides, typical lightning activity data extracted from Blitzortung lightning location system in Vietnam are presented. In addition, a number of studies around the world using lightning data from these location systems to improve the lightning protection performance of transmission lines are briefly introduced. These results and information show the vital role of lightning location systems not only in lightning protection but also in analyzing the causes of failures on power systems.

Application of a Gapless Arrester to Protect 77/66 kV Temporary Overhead Cables

Lightning protection is an issue for temporary overhead cables installed on overhead transmission lines. Existing line surge arresters for overhead transmission line are not expected to provide sufficient lightning protection performance due to the air‐gap discharge delay. Accordingly, a gapless arrester has been developed to protect temporary overhead cables. This paper reports on the results of development tests and experimental constructions. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Computational Investigation of Effects of Expanded Metal Foils on the Lightning Protection Performance of a Composite Rotor Blade

Lightning is one of the most important threats to the safe operation of an aircraft. Rotorcraft can experience lightning strikes on the main rotor blades and tail rotor blades which can seriously affect the rotorcraft and its components in several ways. When lightning strikes a rotor blade made of composite material, electrical–thermal multi-physical phenomena such as the Joule heating effect occur. In this study, an electrical-thermal computational simulation of lightning strikes on composite rotor blades was performed. The simulation analyzed various situations including the presence of a lightning protection system on the composite rotor blade. Emphasis was placed on the effects of geometric parameters of expanded metal foil on the lightning protection performance. In addition, the effects of curvature on thermal and electrical response were investigated. The thermally damaged area was found to substantially increase in inner layers compared to the flat plate case.

Considerations of Photovoltaic System Structure Design for Effective Lightning Protection

Photovoltaic (PV) systems are susceptible to lightning strikes. During a lightning strike, an induced overvoltage is generated in the PV system. This overvoltage can damage the inverters connected to the dc cables. In this article, a comprehensive study is presented to address the installation issues that will influence the induced voltage between the +dc and -dc cables in the PV system. By using the partial element equivalent circuit method, the skin effect and ferromagnetic property of the mounting structures are well modeled. The wiring in the PV module is also considered in the simulation. The influences of the mounting systems, lightning protection systems, PV frames, and dc cable arrangements are thoroughly investigated. The simulation results and discussions provide guidance for PV structure design for maximizing lightning protection performance without adding additional protective devices.

Investigation of Lightning Attachment Risks to Small Structures Associated With the Electrogeometric Model (EGM)

A 3-D Monte Carlo-type random walk model was constructed for the assessment of lightning attachment probabilities to small structures. The simulation assumed buildings had a negligible impact on the propagation of lightning. A purely stochastic propagation model based on a previously proposed gas and charged particle diffusion process was employed. The attachment was based on the electrogeometric model in which striking distance is determined by return stroke peak current. This model allows for hundreds of thousands of samples to be evaluated in the window of a few minutes on readily available consumer computing hardware. Using this model, it became possible to enable characterizing building protection as a probability distribution of striking distance. Such was done to provide a deeper understanding of the impact of building protection design choices than is readily available from binary testing. The model was calibrated for minimum input resolution, which is found to be insensitive to variations in step length and moderately insensitive to variations in propagation angle distribution, resulting in normalized errors of less than 15% (rms). A parametric sweep of geometric features was performed for a large (100 m $\times $ 50 m) rectangular building with catenary wire protection. For heights of less than 30 m, lightning was found to bypass protection structures and strike to the building itself at rates that were insensitive to variations in building height. The extent to which the protection may be recessed from the building’s perimeter was found to have a significant impact. Variations in building aspect ratio were found to be of limited impact except for cases of extreme aspect ratio where competition with the ground appears to have resulted in much better lightning protection performance.

The effect of lightning impulse characteristics and line arrester to the lightning protection performance on 150 kV overhead lines: ATP-EMTP computational approach

This simulation study presents the effect of lightning strikes on the performance of arresters at 150 kV overhead lines. Lightning strikes have several parameters that affect the performance of line arresters (LA), namely lightning charge, and impulse energy. The simulation was attempted by injection of a direct strike to the ground wire with the peak voltage of 10 MV. The peak voltage was varied in terms of wavefront time (Tf) and the duration of lightning impulses (tau). In order to calculate current, charge and impulse energy of LA from various variations of Tf and tau, the trapezoidal numerical integration method is used. The current and impulse energy arising due to direct strikes and various variations of Tf and tau will be compared for each phase so that the influence of Tf and tau can be obtained from the performance of the LA and the current charge and impulse energy values are still within the limits of the IEEE C62.11 standard. The installation of LA and the position of arresters affected the peak voltage of lightning on the phase line when lightning struck it. The line arresters provide a drop in the peak voltage of lightning in phase lines. By installing line arresters in each tower, it will reduce the peak voltage of lightning on the phase line more significantly than the standalone line arrester. It is shown that the line arresters have to install at least six towers to reduce the peak voltage in the phase lines.

Experimental and Numerical Analysis of the Effect of a New Lightning Protection System on Lightning Protection and Aerodynamic Noise Performance of Wind Turbine Blades

In order to tackle the problem of the high failure rate of blades of large wind turbine units due to lightning damage, a new lightning protection system (NLPS) for wind turbine blades is proposed based on the lightning damage mechanism of blades. Firstly, 10 high-voltage discharge tests are performed for blades with and without the NLPS to study the effect of lightning protection. The results show that when the surface of the blade without the NLPS is struck by lightning 10 times, the damage rate of the blade is 100%; for the blade with the NLPS and the lightning attachment position is always on the NLPS in 10 discharge tests, the damage rate of blades is 0% and the lightning protection rate of blades is 100%, indicating that the lightning protection effect for blades with the NLPS is greatly improved. Moreover, the static electric fields of the blades with and without the NLPS are calculated. The results show that the NLPS can shield the electric field around the lower lead wire of the blade, thus effectively reducing the electric field intensity. The NLPS initiates the upward leader more easily than the lower lead wire; therefore, the lightning attachment point is located on the NLPS, thus protecting the blade. Secondly, the aerodynamic and aero-noise characteristics of the blade with and without the NLPS are calculated. The results indicate that the NLPS has little influence on the aerodynamic performance of the blade but has some influence on the aero-noise of the blade. The aero-noise of the airfoil can be reduced at angles of attack of 4°, 8°, 11°, and 15°, but the influence of different phase angles of the airfoil on the amplitude of the sound pressure level (SPL) varies. The aero-noise of the airfoil with the NLPS decreases by 16% and 8% at angles of attack of 4° and 8°, respectively. In general, the design of the NLPS reaches the desired requirements, but it still needs to be further optimized in combination with the blade manufacturing process.

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.

Study on lightning risk assessment and early warning for UHV DC transmission channel

Operation data show lightning faults account for >70% for the main ultra-high voltage (UHV) DC transmission channels, very different from the design view. In order to accurately master the lightning characteristics and the lightning protection performance of the line so as to propose solutions to weak points, this study firstly obtains and analyses the density and strength distributions of lightning risk source. Then the study proposes a set of risk assessment process where the key model electrogeometric model is improved according to the polarity effect of DC line. Then the work realises the calculation of the lightning shielding failure risk of single tower and whole line. The example shows the assessment result is consistent to the line's actual operation. Next, to further evaluate and predict the lightning risk in real time, the study adopts the backpropagation neural network algorithm to integrate the lightning detection data, atmospheric electric fields, and radar echoes to develop the early warning model of lightning risk source, and proposed a method to realise the early warning of lightning damage risk for UHV DC channels. The results show that the effective warning ratio is 73% and the failure-to-warn ratio is 27% which indicates very good application effects.

Parametric Analysis of Lightning Induced Voltage on Distribution Lines using EMTP

Analysis of lightning induced overvoltage has been accepted as one of important subjects for design of better lightning protection system for power lines, especially for distribution system with lower system voltage rather than transmission line system. For estimation of lightning protection performance of power lines, parametric analysis is very useful and necessary to design better lightning protection system taking many factors, such as distance between surge arresters, into account. In this paper, LIV-ATP, which is MODELS code for lightning induced voltage analysis inside ATP (Alternative Transient Program), was compiled to overcome slow execution time and the compiled LIV-ATP was used for parametric analysis of Korea’s 22.9kV distribution system.

Discharge characteristics of different lightning air terminals under composite voltages

Different types of lightning air terminals have been designed over the years. Concern regarding the effect of different types of air terminals, especially the early streamer emission (ESE)-type, remains controversial. This paper describes the discharge characteristics of different types of air terminals, two of which are quite similar to the ESE-type dynasphere, and concludes that the tested non-standard air terminals have discharge characteristics similar to those of Franklin rods and that their lightning protection performance should be similar.

Comparison of lightning protection performance of carbon/epoxy laminates with a non-metallic outer layer

This study shows how a lightning protection layer can be designed to effectively mitigate lightning damage in underlying composite structures. A parametric study was performed to characterize critical lightning protection layer properties that improve composite lightning damage resistance. Simulated 50 kA and 200 kA lightning strikes to pitch-based carbon fiber paper (PCFP)-protected AS4/3506 carbon/epoxy composites were considered in this study. The lightning protection characteristics of various PCFP outer layers were assessed by varying in-plane and through-thickness properties: electrical and thermal conductivities, and electrical and thermal gap conductances. The predicted matrix decomposition in the outermost AS4/3506 ply was significantly reduced by increasing the PCFP in-plane electrical conductivity. While predicted lightning damage decreased slightly with a decrease in thermal gap conductance, varying the electrical gap conductance and the in-plane and through-thickness thermal conductivities did not significantly affect the damage development. Among various PCFP properties, the PCFP in-plane electrical conductivity was the most critical factor in reducing thermal damage development (thus, protecting the underlying AS4/3506 laminate). This parametric study demonstrates that it may be possible to tailor lightweight non-metallic lightning protection layers as an effective alternative to traditional metallic projection layers.