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The upward discharge is a significant factor threatening the operation of wind farms. This paper investigates the inception and development of upward leaders of wind turbines' tip, where blade rotation prevents charge accumulation, using charge density models from laboratory discharges and artificially triggered lightning. The results indicate that larger return stroke currents create higher spatial potentials, and slower downward leader speeds allow for longer development time, favoring the development of upward leaders. As wind turbine sizes increase, the rotation of the blade tips resembles artificially triggered lightning, and the long air gap discharge model may underestimate the development of upward leaders. Calculations from the artificially triggered lightning model reveal improved upward leader formation when further laterally away from the downward leader within a certain distance, elucidating why multiple upward leaders are frequently observed around turbines. The striking distance and attractive radius are largely determined by the development of upward leaders. The absence of corona charge shielding at blade tips means upward leader inception is independent of downward leader velocity, emphasizing downward leaders' significant influence on turbines. Thus, the formula for estimating a wind turbine's lightning incidence requires integrating the return stroke current and velocity of the downward leader. [ABSTRACT FROM AUTHOR]

Lightning is the severest threaten to safe operation of wind turbines. In this letter, the authors present the first altitude‐triggered lightning experiment involving an elevated 12 m‐long wind turbine blade placed on the ground. A total of 50 precursors with amplitude over 62.9 A were observed through measurements of channel‐base current, fast electric field, and optical data. The air gap with around 3–5 m has been bridged between the wire's lower extremity and the metal blade tip during ascending of the rocket and it is observed to be luminous by slow framing rate camera. The precursors are classified into three groups, namely bipolar pulses, unipolar pulses, and group pulses. Excluding the precursors preceding the initial stage and M‐components at the late‐time of the initial stage, five stages are classified. In the first stage, the current remains limited at a relatively small value, while the electric field exhibited a slow rising behavior with positive polarity. In the second stage, the current starts to increase, and the electric field rapidly intensifies due to the accumulating charge, and the wire is assumed to experience an explosion. In the third stage, the reconnection process occurs. The current is characterized by a peak value of 1.45 kA with 10%–90% risetime of 10.4 μs. The electric fields suffer from notable decrease and are characterized by a microsecond‐scale V‐shape pulse. The current cutoff is quite short that almost not found. In the fourth step, the current is characterized by superimposed pulses. The final stage is the channel darkening. Plain Language Summary: Observation results are reported in detail about the altitude‐triggered lightning experiment involving an elevated 12 m‐long wind turbine blade placed on the ground. There are fruitful precursors prior to the beginning of the initial stage. The precursors demonstrate that the air gap with around 3–5 m has been bridged between the wire and the metal blade tip. The precursors are grouped into three groups, namely bipolar pulses, unipolar pulses, and group pulses. The initial stage is classified into five periods. The triggering wire is believed to be vapourized during the second stage. The so‐called initial current variation (ICV), also called reconnection process, occurs at the third stage. The superimposed pulses are found immediately after the reconnection process in the fourth stage. The late‐time of the initial stage is also characterized by superimposed pulses associated with M‐components. This work is potentially helpful to understand the physical process lightning strikes a wind turbine, and design lightning protection strategies for wind turbines. Key Points: First altitude‐triggered lightning experiment associated with an elevated 12 m‐long wind turbine blade has been conducted through simultaneous measurements of current, electric fields and optical dataThe 50 precursors over 62.9 A proceeding the initial stage are classified into three groups: (a) bipolar pulses with the notably initial positive peak and followed by the negative excursion; (b) unipolar pulses with the notably initial positive peak but with quite flat late‐time response; and (c) group pulsesFive stages associated with channel reestablishment are classified according to the measured current and electric field, in which the current cutoff is quite short that almost not found [ABSTRACT FROM AUTHOR]

This paper proposes an Artificial Neural Network (ANN) model using a Multi-Stage method to optimize the configuration of an External Lightning Protection System (ELPS) and grounding system. ELPS is a system designed to protect an area from damage caused by lightning strikes. Meanwhile, the grounding system functions to direct excess electric current from lightning strikes into the ground. This study identifies the optimal protection system configuration, reducing the need for excessive components. The ELPS configuration includes the number of protection pole units and the height of the protection poles. In contrast, the grounding system configuration consists of the number of electrode units and the length of the electrodes. This study focuses on the protection system configuration at a Photovoltaic Power Station, where the area is highly vulnerable to lightning strikes. Several aspects need to be considered in determining the appropriate configuration, such as average thunderstorm days per year, ELPS efficiency, total area of photovoltaic module, area to be protected, soil resistivity, electrode spacing factor, and the total required electrode resistance. The proposed multi-stage ANN model consists of three processing stages, each responsible for handling a portion of the overall system tasks. The first stage is responsible for determining the protection pole configuration. In the second stage, the Lightning Protection Level (LPL) classification is performed. Then, in the third stage, the process of determining the grounding configuration is handled. The analysis results show that the Multi-Stage ANN model can effectively determine the configuration with a low error rate: MAE of 0.265, RMSE of 0.314, and MPE of 9.533%. This model can also explain data variation well, as indicated by the high R 2 value of 0.961. The comparison results conducted with ATP/EMTP software show that the configuration produced by ANN results in fewer protection pole units but with greater height. Meanwhile, ANN produces a configuration with shorter electrode lengths but fewer units in the grounding system. [ABSTRACT FROM AUTHOR]

Distribution lines are an important component of a power system. Lightning disasters have serious adverse effects on the reliability of the power supply in distribution networks. In response to the current lack of research on lightning protection in distribution networks under continuous lightning strikes, we built a transient simulation model and calculated the lightning withstanding level and lightning outage rate of distribution lines under continuous lightning strikes. In addition, the impact of different factors on the lightning withstanding level and lightning outage rate of distribution lines under continuous lightning strikes was calculated for different lightning protection strategies. Finally, differentiated lightning protection strategies based on the lightning outage rate calculation were proposed. [ABSTRACT FROM AUTHOR]

Lightning protection near the fan is the key point of lightning protection in wind farm, which affects the safe and effective delivery of wind power resources. At present, the three-phase multi-gap arrester installed on a base tower behind the collector can cooperate with the zinc oxide arrester to reduce the system failure caused by the arrester failure. However, the chopped wave generated by the multi-gap arrester when it acts is transmitted to the fan box transformer along the line, which may threaten the insulation of the transformer winding. Based on the above problems, this paper builds a simulation model on ATP to analyze the impact of wave clipping of multi-gap arrester on the insulation of fan transformer windings, considers the conventional installation mode and the limit installation mode of multi-gap arrester, and calculates that the wave clipping overvoltage generated by multi-gap arrester after being struck by lightning in two cases is the impact on the insulation of fan transformer. Through the simulation analysis, it is found that the higher the amplitude of the lightning current, the larger the amplitude of the overvoltage generated by the truncated wave, the steeper the wave head, and the greater the threat to the insulation of the fan box. The damage degree of round lightning is less than that of counter lightning. When a multi-gap arrester is installed in a collector tower, the 100 kA lightning current may destroy the insulation of the fan box transformer winding and require additional protective measures. It is recommended that the multi-gap arrester be installed from the next pole tower of the collector tower in the wind farm. [ABSTRACT FROM AUTHOR]

The impact of the topological formation of wind farms upon the lightning induced overvoltages injected into the grid was not covered earlier in literature. However, this topic is highly important to be investigated to allow the usage of the most reliable topology against lightning strikes. For such reason, the paper investigates this point with consideration of most damaging cases as lightning strikes to multi-blades. The testing used ATP software for four main topologies, radial, single-sided ring SSR, double sided ring and star topology. The features defining the similarities in response and the variance range between these topologies were recorded and analyzed. The multi-blade strikes gave an expected increase of 15% to 100% in the injected overvoltage to the grid for all topologies. The star topology showed the most reliable performance by allowing the least injected overvoltage to the grid. The percentage of reduction in the magnitude of the injected overvoltages reached 50.78%, 66.07% and 89.04% for SSR, DSR and star topology respectively with respect to radial topology. Recommendation was provided for design engineers to consider star topology during design phase in terms of more reliable lightning protection. [ABSTRACT FROM AUTHOR]

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Independent lightning rods are often installed in substation grounding systems for lightning protection. The concentrated discharge channel formed when a lightning current flows to the ground through a grounding electrode will cause electromagnetic interference to the directly buried secondary cable. And the three-dimensional structure of the discharge channel will affect the transient electromagnetic field distribution, thereby affecting the electromagnetic transients on cable shields. In order to explore the influence of soil discharge phenomena on the electromagnetic interference of the directly buried secondary cable, in this paper, we carried out experiments on cables in two different grounding modes, single-ended and double-ended grounding, and captured image of soil discharge channels. The results show that the cable grounding mode will affect the coupling mode that causes the shielding layer current. The relative spatial position of the soil discharge channel and the cable has a significant impact on the magnitude of the shielding layer current under both grounding modes. The water content and salt content of the soil also have different degrees of influence on the coupling current of the shielding layer in different grounding modes. [ABSTRACT FROM AUTHOR]

Lightning protection is important for weather radars to prevent critical damage or outages, but this can have negative effects on data quality. The existing lightning protection of the German Meteorological Service (Deutscher Wetterdienst, DWD) polarimetric C-band weather radar network consists of four vertical poles with a maximum diameter of 10 cm. During radar operation, these rods cause local scattering in the near field of the antenna, resulting in negative impacts on radar products. One effect is the removal of significant transmission power from the main beam axis and its addition to other areas or the side lobes. This results in wrongly localised precipitation fields in a radial direction. The second effect is the loss of transmitted and received power, appearing as a decrease in system gain, and subsequently an underestimation of all power-based radar moments in the vicinity of the rods. The underestimation in radar reflectivity Z then leads to a negative bias of approximately 20 % in the actual rain rate if a Z – R relationship is applied. These detrimental effects on data quality led to the requirement of developing a new lightning protection concept. The new concept must minimise the effect on data quality but also provide sufficient protection from lightning strikes according to the existing regulations and requirements. Three possible lighting protection concepts are described in this paper: two using vertical rods of different diameters (16 and 40 mm) and one with horizontally placed rods outside the antenna aperture. Their possible influence on data quality is quantified through a dedicated measurement campaign by analysing resulting antenna patterns and precipitation sum products. Antenna patterns are analysed with respect to the side-lobe levels compared to antenna patterns without lightning protection and the original lightning protection. With the newly tested lightning rods, the apparent side-lobe levels are slightly increased compared to an antenna pattern taken without lightning protection but are within the accepted antenna specifications. Compared to the original lightning protection, a decrease of up to - 15 dB in apparent side-lobe levels is found for all tested lightning protection options. Beam blockage is substantially reduced compared to the existing lightning protection, as shown by the evaluation of quantitative precipitation estimation (QPE) sums. These results and some structural considerations are a solid basis to recommend the installation of four rods with a maximum 40 mm diameter for all 17 radar systems of the DWD weather radar network. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of transmission line parameter calculation formulations on surge arrester performance in response to lightning strikes. This evaluation consists of comparing power and energy dissipated in surge arresters, as well as critical currents and line backflashover rates. The lightning performance of surge arrester installed in a typical Brazilian 138 kV transmission line is assessed by simulations in ATP software, while transmission line parameters are calculated in 3 different ways, namely: (i) Carson formulation, (ii) Nakagawa formulation considering the electrical parameters of the ground constant with the frequency, and (iii) Nakagawa formulation considering the frequency-dependent characteristics of the soil. Taking as reference the results determined by Carson's formulation (since this formulation is the most used in programs for calculating transients, such as ATP), it is shown that Nakagawa's formulations considering both constant and frequency-dependent soil parameters can lead to differences for the cases of unprotected lines, partially protected (lightning arresters in one or two phases) and fully protected (lightning arresters in all phases), resulting in an inaccurate prevision of insulation failure, leading to an increase in the backflashover rate. [ABSTRACT FROM AUTHOR]

The widespread use of composite materials with low electrical conductivity in modern advanced aircraft has placed higher requirements on lightning protection for airborne equipment. To ensure the safe operation of aircraft under a lightning environment, the internal cables and cable tracks of composite aircraft are modeled. The lightning protection performance of cables is calculated for different types and shielding parameters, and the effect of the cable layout inside a composite aircraft on the protection performance is analyzed. The role of the cable track in lightning protection is also verified. The calculation results show that the cable shield and track structure can provide good lightning protection for the cable in the electromagnetic exposure area, and the layout of the cable inside the aircraft has a greater impact on the protection performance. The analysis of cable shielding measures and their influencing factors can provide a reference for the performance improvement of cable screening measures for the lightning protection of composite aircraft. [ABSTRACT FROM AUTHOR]

Introduction. Insulation coordination requires accurate prediction of overvoltages at various points within a substation. Computer simulations of electromagnetic transients in real structures of substations become more precise due to the improvements of used models. Goal. This paper discusses in a first step the use of the modified ZnO arrester dynamic model alongside other substation equipment models, considering electrical phenomena like the corona model for reproducing the stresses that lightning can cause in an air-insulated substation and (method) then conducting a statistical approach based on the Monte Carlo method. The implemented MATLAB/ATP procedure estimates not only the substation Mean Time between Failures (MTBF), but also is used to select surge arresters or substation basic insulation levels (BILs). In this procedure ATP transients program is used to calculate lightning overvoltages and multicore environment for the calculations. Results. The obtained MTBF curves offer guidance for selecting appropriate insulation levels based on specific system requirements and conditions. The obtained results comply well with existing international insulation standards. This valuable approach significantly contributes to the field of lightning protection. References 31, tables 3, figures 10. [ABSTRACT FROM AUTHOR]

The effects of generating pulsed radiation by a long spark discharge are important for the development of lightning models and applications related to lightning protection. In experiments with a Marx generator simulating a lightning discharge, we detected the radiation in the form of a single ultrawideband electromagnetic pulse (UWB EMP) about 200 ps in duration, and rising time about 100 ps. UWB EMP generation occurs during the breakdown of a "rod–rod" 4 m long gap. Pulses of almost unipolar shape are observed in more than half of all positive discharges. EMP emission occurs before the main stage, and corresponds to the start of the upward leader from a grounded electrode. In negative discharges, pulses are also observed, but less frequently and with a smaller amplitude. The UWB EMPs, given their large amplitude (more than 100 V/m at a distance of 90 m from the discharge), can be considered as possible new lightning damage factors. Plain Language Summary: A Marx generator with an operating voltage of several megavolts is used to simulate a lightning stroke of a grounded object. The generation of a short electromagnetic pulse (several hundreds of picoseconds long) has been detected during a breakdown of a long air gap using special electromagnetic probes. Such a pulse is observed in the majority of positive discharges in the "rod–rod" gap. Subnanosecond pulse can be regarded as possible new damage factor of lightning strokes. Key Points: Marx generator allows studying generation of ultra‐wideband electromagnetic pulses (EMPs) by long spark discharges that model lightningSingle EMP about 200 ps duration is generated by 4‐m long spark discharge in a rod‐rod geometryPulses of almost unipolar shape with up to 200 V/m amplitude are observed at 90 m distance from more than half of all positive discharges [ABSTRACT FROM AUTHOR]

Compressive performances of composite structures can be significantly decreased due to the lightning strike damage, so the structures with lightning frighten must be considered lightning protection design. In this study, compressive experiments after lightning strikes were conducted on non‐protected, 12‐layer interlaminar carbon nanotube film (CNF) protected, and traditional surface silver coating (TSSC)‐protected composite laminates. A numerical analysis procedure was established, incorporating a lightning strike ablation damage simulation (LSADS) module and compressive residual strength calculation (CRSC) module. The procedure's effectiveness was verified by the experiment results. Based on this procedure, the compressive performances and the possible failure mechanism of laminates after lightning strikes were analyzed. The results show that the laminates with TSSC protection and 12‐layer interlaminar CNF protection can increase compressive residual strength compared with non‐protected laminates. The predominant compressive damages of the laminates after lightning strikes are fiber‐matrix shear damage and fiber fracture damage. Optimized one‐layer interlaminar CNF protection with a thickness of 0.36 mm can increase the laminate compressive strength but decrease the structural weight. This study offers a reference and basis for the lightning strike protection design of composite structures. Highlights: CNF in lightning strike protection of composite structures.Compressive failure mechanism of composite laminates after lightning strikes.A numerical procedure to evaluate lightning damage and compressive performances.Design of interlaminar CNF protection. [ABSTRACT FROM AUTHOR]

The growing use of thermoplastic composites (TPCs) like low-melting polyaryletherketone (LM-PAEK) matrices reinforced with unidirectional carbon fiber (CF) in aircraft structures presents a significant challenge in terms of lightning strikes and electromagnetic interference shielding during aircraft operations. This is due to the weak electrical conductivity of TPC structures, which results in widespread damage when struck by lightning. The repair and maintenance of these extended damaged sites can increase operational costs and loss of flights. Several lightning strike protection (LSP) systems have been developed and implemented to address these concerns. This study evaluated a highly conductive coating with a low filler rate for its effectiveness as an LSP solution for TPCs on exterior aircraft surfaces. The TPC panel without any coatings was first studied. Subsequently, the level of conductivity was increased by incorporating the nanoscale conductive fillers, silver-coated copper (Ag/Cu) nanoflakes, with a silver content of 20 wt.% (Ag20/Cu) and 30 wt.% (Ag30/Cu), correspondingly, into the coating at two loadings of 55 wt.% and 70 wt.% in an epoxy carrier for the surface coatings. The behavior of electrical and surface conductivity was thoroughly examined to understand the impact of Ag/Cu with a high aspect ratio and the effectiveness of the LSP solution. In addition, the spray-coated TPC panels underwent rigorous Zone 2A lightning strike testing using simulated lightning current, in agreement with the industry standard of Society of Automotive Engineers (SAE) Aerospace Recommended Practice (ARP) 5412B. Despite the higher resistance due to the lower conductive coating weight, the TPC panels with Ag30/Cu at loading of 70 wt.% achieved better results than those with Ag30/Cu at loading of 55 wt.%. This is evidenced by the minor structural delamination and CF breakage on the front surface, which proposes a new economic route for a sustainable post-processed LSP system in the aviation industry. [ABSTRACT FROM AUTHOR]

It is of great importance to choose low-cost, high-performance/efficient and operating and protection equipment in accordance with the applicable legislation in electrical facilities. It is necessary to make calculations for the selection of the most suitable cable/line, measuring and protection system equipment. In this study, panel-inverter compatibility calculation, voltage drop, current control, short circuit, lightning risk and protection calculations, grounding resistance and grounding conductor calculations and tilt angle calculation were made for a grid connected photovoltaic system with a power of 0.4 MWe. It has been calculated that the allowable voltage range and maximum powerpoint voltage values of the selected inverter are compatible with the panel system. With voltage drop and current control calculations, copper cable cross section for each inverter output and solar board output were found to be 3x70+35 mm2 and 2(3x185+95) mm2, respectively, and transformer low voltage busbar 60x10 mm2. In order not to deform the low voltage busbars in peak short-circuit current, they should be placed at 10 cm intervals for 80 cm length. According to the transformer low voltage side phase-earth short circuit current, the cross-section of the grounding conductor should be at least 53.97 mm2 copper conductor. In the lightning protection facility of the panels, according to the rolling sphere method, it has been calculated that the air termination rods should be at least 0.84 m above the upper point of the solar panel. The optimum fixed panel tilt angle was found to be 32.08°. The calculations used in the study will benefit the practitioners in the design of grid-connected photovoltaic systems, in the selection of the most suitable electrical equipment with minimum size. [ABSTRACT FROM AUTHOR]

This paper elaborates on the hazard mechanisms of diff erent types of lightning, such as direct lightning, electrostatic induction lightning, and electromagnetic induction lightning. Based on on-site investigation and laboratory testing, this paper analyzes the pathways of lightning intrusion into ZPW-2000A track circuits, comprehensively analyzes the hazard mechanisms and intrusion pathways, formulates corresponding horizontal and vertical lightning protection measures, and explains the lightning protection characteristics such as "leakage", "resistance", and "suspension". [ABSTRACT FROM AUTHOR]

The application of arresters is critical for the safe operation of electric grids against lightning. Arresters limit the consequences of lightning-induced over-voltages. However, surge arrester protection in electric grids is challenging due to the intrinsic complexities of distribution grids, including overhead lines and power components such as transformers. In this paper, an optimal arrester placement technique is developed by proposing a multi-objective function that includes technical, safety and risk, and economic indices. However, an effective placement model demands a comprehensive and accurate modeling of an electric grid's components. In this light, appropriate models of a grid's components including an arrester, the earth, an oil-immersed transformer, overhead lines, and lightning-induced voltage are developed. To achieve accurate models, high-frequency transient mathematical models are developed for the grid's components. Notably, to have an accurate model of the arrester, which critically impacts the performance of the arrester placement technique, a new arrester model is developed and evaluated based on real technical data from manufacturers such as Pars, Tridelta, and Siemens. Then, the proposed model is compared with the IEEE, Fernandez, and Pinceti models. The arrester model is incorporated in an optimization problem considering the performance of the over-voltage protection and the risk, technical, and economic indices, and it is solved using the particle swarm optimization (PSO) and Monte Carlo (MC) techniques. To validate the proposed arrester model and the placement technique, real data from the Chopoghloo feeder in Bahar, Hamedan, Iran, are simulated. The feeder is expanded over three different geographical areas, including rural, agricultural plain, and mountainous areas. [ABSTRACT FROM AUTHOR]

This paper discusses main characteristics and features of the use of metal perforated foils and metal knitted and knitted–soldered wire meshes in the creation of effective lightning-protection systems for carbon composite structures. [ABSTRACT FROM AUTHOR]

A review of materials used for lightning-protection systems of polymer composite materials has been presented. The features of the manufacture of metal perforated foils and metal knitted wire meshes used to create effective lightning-protection systems for carbon composite structures have been considered. [ABSTRACT FROM AUTHOR]

This paper presents a review of industrially produced lightning protection systems for PCM structures containing perforated metal foils and metal knitted wire meshes. [ABSTRACT FROM AUTHOR]

From the two decades, the utilisation of electronic equipment in aerospace applications drastically increased. High-intensity radiated fields highly influence the operation of electronic equipment. As per the survey, an economy flight is affected by a lightning strike for every 1000 hours of its journey. For the fabrication of the airplane structure, fibre-reinforced materials (FRP) were used, but there is a flaw in FRP's. FRP's having low conductance, which cannot flow the currents produced by the lightning strike, which causes delamination and embrittlement of the airplane structure. A different composite material was introduced as a lightning strike protection (LSP) layer to overcome the said problem. The electromagnetic protection is obtained in terms of reflection and absorption of the EM waves. Al6061 material is reinforced with SiC and flyash at different combinations and obtained good mechanical, absorption loss, and reflection loss properties. The maximum reflection loss of 32.61 dB and absorption loss of 32.60 dB was obtained. [ABSTRACT FROM AUTHOR]

The initial stage in aircraft lightning protection design and safety certification involves delineating the lightning attachment zone. The lightning leader's development is inherently random, favoring the shortest path to the aircraft fuselage. In response, we employ the enclosing ball method to establish the lightning attachment zone. First, define the center point of the aircraft as the coordinate position for the sphere's center, creating a sphere with a specified radius. The leader's initial position is then selected from any point on the sphere. Second, by calculating distances between the leader's position and various areas on the aircraft surface, we determine the shortest path. The corresponding aircraft surface area along this path is identified as the lightning attachment zone for the leader. Subsequently, choose a new leading position on the sphere and iterate through the calculation process until all sphere positions are considered. Finally, tally the occurrence frequencies for all calculated attachment areas, representing the attachment probability of each area based on its frequency of occurrence. This paper not only compares our method with the electrostatic field simulation method but also contrasts it with the probability distribution of lightning attachment points obtained from aircraft flight experiments. The comparison results are highly favorable, providing robust verification for the correctness of our approach. [ABSTRACT FROM AUTHOR]

Floating solar photovoltaic (FPV) technology has been gaining popularity in various parts of the world to address the growing clean energy demand and land scarcity challenges posed by conventional solar PV installations. This paper presents a comprehensive review of the recent progress in FPV research and actual implementations, highlighting advancements, challenges, and future prospects in this dynamic and promising field in Malaysia.

The gas blast arc-extinguishing lightning protection gap is a new type of lightning protection device based on airflow active arc-extinguishing. This paper establishes an airflow and arc mathematical model for calculating and analyzing air flow and arc motion processes. Besides, the finite element software ANSYS 14.0 is employed for the arc-extinguishing simulation in the pressure field, interaction arc, and airflow processes. Accordingly, the test analysis effects of the arc-extinguishing gap lightning protection test are verified. High-speed cameras, recording oscillograph arc-extinguishing images, and arc waveforms are employed in the process to obtain the airflow response time and arc-extinguishing time effectively based on the data analysis. Comparing the actual results with the simulation results demonstrates the arc-extinguishing reliability and provides an effective scientific basis for its practical application. [ABSTRACT FROM AUTHOR]

Lightning strikes can cause equipment damage and power outages, so the distribution system's reliability in withstanding lightning strikes is crucial. This research paper presents a model that aims to optimise the configuration of a lightning protection system (LPS) in the power distribution system and minimise the System Average Interruption Frequency Index (SAIFI), a measure of reliability, and the associated cost investment. The proposed lightning electromagnetic transient model considers LPS factors such as feeder shielding, grounding design, and soil types, which affect critical current, flashover rates, SAIFI, and cost. A metaheuristic algorithm, PSOGSA, is used to obtain the optimal solution. The paper's main contribution is exploring grounding schemes and soil resistivity's impact on SAIFI. Using 4 grounding rods arranged in a straight line under the soil with 10 Ωm resistivity reduces grounding resistance and decreases SAIFI from 3.783 int./yr (no LPS) to 0.146 int./yr. Unshielded LPS has no significant effect on critical current for soil resistivity. Four test cases with different cost investments are considered, and numerical simulations are conducted. Shielded LPSs are more sensitive to grounding topologies and soil resistivities, wherein higher investment, with 10 Ωm soil resistivity, SAIFI decreases the most by 73.34%. In contrast, SAIFIs for 1 kΩm and 10 kΩm soil resistivities show minor decreases compared to SAIFIs with no LPS. The study emphasises the importance of considering soil resistivity and investment cost when selecting the optimal LPS configuration for distribution systems, as well as the significance of LPS selection in reducing interruptions to customers. [ABSTRACT FROM AUTHOR]

The distribution line is widely distributed and the span of pole-towers is small. However, the existing lightning positioning system has limited positioning accuracy, and the lightning strike coordinates it locates have certain deviations for the distribution network. The lightning hazard risk divided by lightning density is not sufficient to support the differentiated lightning protection transformation of the distribution network. The environment of the underlying surface where the pole-tower is located has a significant impact on lightning activity, so this paper combines terrain, climate, lightning current characteristics, and historical lightning trip data to finely evaluate the lightning risk level in the distribution line pole-tower area. This paper provides a detailed analysis of the relationship between different underlying surface environments and lightning current characteristics and utilizes the entropy weight method to construct a comprehensive lightning disaster risk index, then evaluates the risk level of lightning disaster in different regions, and corrects it through lightning fault data. Overlaying the risk level of the area and the distribution map of the pole-tower foundation coordinates, it will obtain the distribution of lightning hazard-pregnant risk at the pole-tower area, which would contribute to guiding the differentiated lightning protection transformation of the line. Compared to traditional unified lightning protection renovation methods, differentiated lightning protection methods that integrate factors such as pole-tower structure, wire type, and lightning risk level can achieve significant lightning protection effects at a lower economic cost. Taking Nanchang City as an example, risk assessment and lightning protection renovation were conducted on 21 distribution lines. The average number of lightning trips per year is 55 before the renovation, but it is only 4 after the renovation, which the number of lightning trips significantly reduce. This verifies the effectiveness of using lightning hazard-pregnant assessment results to guide differentiated lightning protection methods. [ABSTRACT FROM AUTHOR]

The expression "lightning never strikes twice" is questioned in this paper because, among the randomness of lightning impacts, some spots are hit even more than twice year after year. This article introduces the recurrent lightning spots (RLS) concept, which are locations periodically impacted by cloud‐to‐ground lightning every consecutive year over a certain period. RLS are investigated in two regimes, with markedly different lightning climatology but similar orography, for 10 consecutive years: Catalonia (North East of Spain, Europe) and Barrancabermeja (North Central Colombia, South America). Results revealed 148 and 916 RLS in Catalonia and Barrancabermeja, respectively. RLS in both regions are typically found to be related to tall structures, mountain peaks, and steep terrain. The method allowed us to identify those tall towers and orographic relief frequently affected by lightning that are not detected with the mere computation of the ground flash density. In the case of Catalonia, some RLS are found offshore. Besides the scientific interest in understanding lightning, the new concept of RLS provides additional and valuable information applicable to lightning protection engineering. Plain Language Summary: The expression "lightning never strikes twice" is questioned in this paper because it shows that some spots are hit even more than twice: year after year. The RLSs (RLS) concept is presented, which are locations where lightning strike them periodically. The two regions of study with markedly different lightning climatology but similar orography are Catalonia (North East of Spain, Europe) and Barrancabermeja (in North Central Colombia, South America). RLS in both regions are typically found to be related to tall structures, mountain peaks and steep terrain. In the case of Catalonia, some RLS are found offshore. RLS new concept provides valuable information to lightning protection engineering. Key Points: Recurrent lightning spots (RLS) are targets with at least one cloud‐to‐ground lightning per year during a certain number of consecutive yearsIn Catalonia (Spain), 13% of the RLS are tall towers, 72% are mountainous peaks and 5% are offshore sitesThe method effectively finds tall structures affected by lightning in tropical climates [ABSTRACT FROM AUTHOR]

The study of lightning radiation spectra is of great importance for the scientific study of lightning physics and lightning protection systems of the electromagnetic threat of lightning. The frequency spectra characteristics of very high frequency (VHF) electric field radiation with the corresponding low frequency (LF) electric field changes during various events of the physical process of the seven positive ground flash events have been analyzed using the short-time Fourier transform (STFT) method. It was found that the frequency range of initial breakdown (IB), leader (L), and continuing current (CC) was 24-52 MHz, 30-50 MHz, and 30- 50 MHz, respectively, with the arithmetic mean (AM) initial breakdown (IB), leader (L), and continuing current (CC) of 39 MHz, 39 MHz, and 38 MHz, respectively. The differences in the frequency spectral pattern range of 24-52 MHz between different positive ground flash events may indicate that these events have different discharge mechanisms and that frequency domain information is required to identify these various discharge events. We also found that time delay between wideband and narrowband return stroke (RS) radiation is about 2-17 µs. [ABSTRACT FROM AUTHOR]

Indonesia is frequently plagued by intense lightning activity, leading to a multitude of incidents causing harm and devastation. As a proactive measure to mitigate future damages, an extensive research endeavor focusing on lightning peak currents was under taken in the maritime tropical continent region, particularly in Cilacap. This research aimed to curtail potential risks and enhance safety measures in the region. The impetus for this investigation stemmed from a series of incidents involving tank explosions in Cilacap, located in Central Java, Indonesia. These occurrences served as pivotal triggers, prompting a comprehensive analysis of lightning peak current statistics. According to the data collected, there exists a 85% probability of a lightning event in Cilacap producing a peak current of 18 kA. The implications of this research extend beyond the local scope, as the statistical insights gleaned from this study can serve as a foundational basis for the development of both national and international lightning protection standards. By integrating local statistics into the broader framework, a more comprehensive and effective approach to lightning protection can be devised, fostering greater resilience and safety measures not only in Cilacap but also in regions facing similar challenges globally. [ABSTRACT FROM AUTHOR]

A separable connector is used for the power cables and apparatuses in renewable energy systems. The shield of the collector cable is sometimes an open circuit at one end to reduce power loss due to the shield current. However, this has a disadvantage from the viewpoint of lightning protection. The semiconductive part of the separable connector is grounded for safety. The ground potential rise due to a direct lightning strike to a wind tower sometimes damages the collector cables and power apparatuses in the wind tower. Combustion in a cable is one of the most serious types of lightning‐caused damage. This paper describes an experimental study on fire ignition in a collector cable caused by a ground potential rise due to a direct lightning strike to a receptor. The mechanism leading to fire ignition is discussed based on the experimental results. This paper also proposes a countermeasure against such fire ignition. [ABSTRACT FROM AUTHOR]

A 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. [ABSTRACT FROM AUTHOR]

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This paper systematically studies the flashover probability of wind turbine blade lightning arrester and the impact of strong electromagnetic pulses on the local and surrounding wind turbines during lightning strikes. The research results indicate that the flashover probability of direct lightning strikes by the wind turbine blade lightning arrester is almost negligible, and the strong electromagnetic pulse of wind turbine blade during lightning strikes has a serious impact on the electronic equipment of the machine, while the impact on the surrounding wind turbine is relatively small. At the same time, the calculation formula for the reflection of lightning current on the carbon brush between the wind turbine hub and the engine compartment during the flashing of the wind turbine blades is provided, and the calculation method for calculating the spatial gradient distribution of electromagnetic field intensity using Biot -- Savart Law theorem is applied. The limitations of using wind turbine blades for lightning protection are pointed out, and a technical route for achieving wind turbine lightning safety is proposed, which can be used as a reference for wind turbine lightning protection technicians. [ABSTRACT FROM AUTHOR]

Damage inflicted upon facilities and equipment within a building primarily results from lightning strikes. Consequently, the installation of lightning rods emerges as a vital necessity to augment the overall protection of a structure. This not only serves the collective welfare but also aligns with governmental interests. The imperative nature of this measure lies in its role in safeguarding a myriad of equipment and production activities that involve the use of flammable materials. These materials come in various forms, encompassing solids, liquids, and gases, both within the building and its surrounding areas.Within the realm of lightning protection systems (LPS), this research specifically adopts the conventional Franklin rod as the preferred choice for factory buildings. The study accentuates the essential need for a Level IV protection rating within the LPS framework. Furthermore, it strongly advocates for the multiplication of lightning protection rods to fortify the defense mechanism. A minimum recommendation of four rods per building roof is proposed, highlighting the critical significance of proactive measures. These measures are indispensable to ensure comprehensive protection against potential damages caused by lightning strikes in industrial settings. The proactive installation and adherence to these protective measures underscore the commitment to maintaining a secure and resilient environment for both equipment and personnel. [ABSTRACT FROM AUTHOR]

The global PV market has grown extensively for small- to large-scale systems. Inevitably, this leads to the increased development of PV technology. PV systems are intrinsically exposed to weather phenomena. One such phenomenon is lightning. Direct and indirect effects of lightning can cause damage to PV systems. However, lightning protection for PV systems is often neglected and existing standards for protection are underdeveloped. In this paper, previous work is analysed to understand the interaction between lightning and PV systems and to ascertain gaps in current knowledge thereof. Investigation of these aspects will ultimately assist in understanding lightning risk, protection system design and aid in the development of lightning protection standards for PV in the renewable energy industry. The article also presents a specific case study, outlining the lightning protection system of a 3200W photovoltaic plant on a farm. The work includes a thorough description of the lightning protection system, addresses issues related to the contamination of PV surfaces, and proposes practical measures to ensure the safe and reliable operation of photovoltaic systems under adverse weather conditions. The experimental results affirm the significance of implementing lightning protection systems to ensure the robust performance of solar power plants.

Abstract This paper conducts the frequency‐dependent grounding system impact on externally gapped line arresters (EGLAs) operation and their placement effects on the lightning performance of a transmission line (TL). The study involves placing EGLAs at different phases of a 400‐kV double‐circuit TL with two downstream shield wires and selecting the optimal state with fewer back‐flashover incidents. The results show that using a non‐linear grounding system leads to a higher back return current from insulators or EGLAs, resulting in a higher flashover rate compared to the frequency grounding system (FGS). Installing four EGLAs in the middle and upper phases of the TL provides satisfactory lightning protection, and the flashover probability is zero and 4.2% for the FGS and the non‐linear grounding system, respectively. A sensitivity analysis including soil resistor variation, economic analysis, and grounding electrode configuration has been performed that confirms installing downstream shield wires and EGLAs is an effective and economical technique for lightning protection.

Distribution lines are an important component of a power system. Lightning disasters have serious adverse effects on the reliability of the power supply in distribution networks. In response to the current lack of research on lightning protection in distribution networks under continuous lightning strikes, we built a transient simulation model and calculated the lightning withstanding level and lightning outage rate of distribution lines under continuous lightning strikes. In addition, the impact of different factors on the lightning withstanding level and lightning outage rate of distribution lines under continuous lightning strikes was calculated for different lightning protection strategies. Finally, differentiated lightning protection strategies based on the lightning outage rate calculation were proposed.

Distribution of lightning plays a key role in lightning protection of transmission lines. The design of wind deviation under lightning overvoltage of the transmission tower is an empirical parameter in the transmission line design code. Meteorological data from Hong Kong are investigated to analyze the joint distribution of lightning and wind speed. It has been uncovered that daily cloud-to-ground (CG) flashes follow the Burr distribution, which is highly skewed toward a few days with notable lightning. The lightning and wind follow a Gumbel copula joint distribution. According to empirical and theoretical distribution, there are 239 days with more than 1,000 CG lightning flashes per day, and approximately 20% of these days have a maximum wind speed of approximately or over 15 m/s. In 5 days with the number of CG lightning flashes above 30,000, 3 days have a maximum wind speed of over 15 m/s and the other 2 days have a maximum wind speed of over 10 m/s, which suggests that the severe convection with a squall line contributes much to the likelihood of the days with high wind and lightning storms. [ABSTRACT FROM AUTHOR]

This paper conducts the frequency‐dependent grounding system impact on externally gapped line arresters (EGLAs) operation and their placement effects on the lightning performance of a transmission line (TL). The study involves placing EGLAs at different phases of a 400‐kV double‐circuit TL with two downstream shield wires and selecting the optimal state with fewer back‐flashover incidents. The results show that using a non‐linear grounding system leads to a higher back return current from insulators or EGLAs, resulting in a higher flashover rate compared to the frequency grounding system (FGS). Installing four EGLAs in the middle and upper phases of the TL provides satisfactory lightning protection, and the flashover probability is zero and 4.2% for the FGS and the non‐linear grounding system, respectively. A sensitivity analysis including soil resistor variation, economic analysis, and grounding electrode configuration has been performed that confirms installing downstream shield wires and EGLAs is an effective and economical technique for lightning protection. [ABSTRACT FROM AUTHOR]

Existing transmission lines and pipelines are frequently crossed and erected in parallel, meaning that if lightning strikes a wire and causes insulator flashovers, the resulting lightning current will spread through the grounding of the tower where the flashover insulator is located. This dispersion of current can lead to overvoltage effects on nearby pipelines. This study performs simulation calculations to analyze the overvoltage experienced by pipelines due to the dispersion of grounding current from the tower. Furthermore, this paper proposes a method for protecting the pipeline from such an overvoltage. Firstly, the lightning transient calculation model of a transmission line tower is constructed using the electromagnetic transient software ATP-EMTP 5.5. The model calculates the effects of lightning peak currents and soil resistivity on the distribution characteristics of lightning current in the tower, specifically in the area where the flashover insulator is located. Subsequently, a calculation model of the tower grounding grid–natural gas pipeline is developed, taking into account the distribution characteristics of lightning current in the tower. This model analyzes the impact of lightning peak currents, soil resistivity, and pipeline spacing on pipeline overvoltage. Finally, the effectiveness of the solid-state decoupler in mitigating lightning overvoltage in the pipeline is verified. The results demonstrate a positive correlation between the lightning current entering the tower grounding grid through the flashover insulator and the lightning current distribution characteristics. The solid-state decoupling device proves to be effective in reducing the voltage of the pipeline insulation layer, and the simulation results provide the optimal laying length of the bare copper wire. [ABSTRACT FROM AUTHOR]

In Hokuriku area, where lightning strikes with a large amount of electric charge occur in winter, failure rate of lightning protection devices such as surge arresters and devices with built‐in zinc oxide (ZnO) elements tends to be high. In order to prevent failure of surge arresters, 5 kA surge arresters which have a larger energy capability are installed on terminal poles of distribution lines. As for lightning protection of pole‐mounted distribution transformers, insulators with ZnO are utilized to support medium‐voltage drop wires connected to the transformers on non‐terminal poles. In this paper, we have studied the effect of insulators with 5 kA ZnO which have a larger energy capability as a lightning protection measure for transformers on terminal poles using lightning‐surge analysis. The lightning outage rate, which is the total of insulation breakdown rate and failure rate of a lightning protection device, is found to be lower in the case of insulators with 5 kA ZnO than in the case of 5 kA surge arresters. In addition, by replacing 5 kA surge arresters with insulators with 5 kA ZnO, a cost reduction effect is found to be also expected. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As wind energy is recognized as an inexhaustible source, the use of equipment, such as turbines, is essential for generating electricity. One critical aspect in the wind farm design process revolves around ensuring lightning protection for the equipment in Wind Turbines (WT). Failures in the receivers placed within wind turbine blades to intercept lightning strikes can lead to the destruction of the blades or the entire wind turbine. Therefore, the receiver plays a pivotal role in determining the effectiveness of the Lightning Protection System (LPS) on the wind turbine. This study focuses on the numerical implementation of eight types of receivers on the blades of a typical wind turbine to analyze their impact on the LPS. A Finite Element (FE) computer model is developed to estimate the electric field's intensity at the blade surface caused by lightning. The study assesses the ability of various receiver positions to intercept lightning by comparing the maximum expected field intensity surrounding the receivers and the number of electric field lines intercepted by the receivers. Additionally, the positioning of lightning attachment points on the wind turbine blade aligns closely with those derived from laboratory measurements, validating the accuracy of the numerical method. [ABSTRACT FROM AUTHOR]

Problem. Modern international standards in the field of lightning protection, when assessing the probability of a lightning strike into an object, do not take into account the statistical distribution of the lightning current. Goal. Justification of the expediency of taking into account the statistical distribution of the lightning current with a determined probability of lightning striking the elements of the object, and the effectiveness of the application of the improved «rolling sphere» method. Methodology. Method of mathematical modeling, based on RSM with additional consideration of the probability distribution of lightning current. Results. The expediency of taking into account the statistical distribution of lightning current at the determined probability of lightning striking the elements of the object has been proven. The effectiveness of the improved «rolling sphere» method, implemented in the form of a computer program, which takes into account the given probability distribution of lightning current in the range from 2 kA to 200 kA, has been proved. The expediency of introducing the concept of «average value of the area of the collection area» is substantiated, taking into account the probability of lightning with a current in a given range. It has been established that the application of the standardized formula leads to a significant (many times) overestimation of the predicted number of lightning strikes to the object, if the height of the object exceeds 20 m. The reasons for the difference, according to the author, are due to the following properties of the standardized methodology: usually, the real shape of the object is not taken into account; statistical distribution of lightning current is not taken into account; it is based on the results of experimental studies obtained mainly for mast or rod-type objects in laboratory conditions with a limited discharge interval. Practical value. This approach will provide an opportunity to optimize the layout of lightning arresters during the restoration of objects, taking into account green reconstruction. The obtained results are proposed for consideration by the Technical Committee TC 81 IEC for inclusion in the next editions of the standards.

Abstract Tower 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.

Although the electrical properties of carbon fibers and carbon fiber composites are critical to the design of composite materials, a direct measurement of the transverse electrical resistivity of a single carbon fiber has not yet been reported. Significant challenges arise in fabricating specimens and making electrical resistance measurements due to the geometry and small diameter of a single carbon fiber (about 4–7 μm). In this study, we report a specimen design and fabrication technique for measuring the transverse electrical resistance of an individual carbon fiber by the van der Pauw method. IM7 carbon fiber specimens are fabricated by a combination of photolithography and the focused ion beam. Specimen thickness, which is required for resistivity calculations, is measured by atomic force microscopy. We measure mean transverse electrical resistivity of (9.3 ± 0.3) × 10−5 Ω m, which is roughly six times greater than the reported longitudinal values. Our measurement technique can be applied to a range of conductive fibers. More accurate measurements of the electrical conduction in carbon fibers are critical for applications such as electromagnetic interference shielding, structural health monitoring, and lightning strike protection. [ABSTRACT FROM AUTHOR]