Lightning Strikes Research Articles

Penggunaan Metode Rolling Sphere untuk Pengamanan Jaringan 150 kV dari Sambaran Petir Langsung

Lightning strikes can cause protection failure at substations such as equipment damage at substations due to insulation failure or what is known as flashover. Because of that, a lightning strike protection system is needed to minimize the occurrence of direct lightning strikes to equipment and buses at the substation. This study discusses the modeling of the protection of the substation from direct lightning strikes using the rolling sphere method at the Wonosari-pedan 150 kV substation using lightning rod poles. The calculation results show that with the configuration of a lightning rod as high as 21 m and the use of a ground wire of 17.8 m it meets the safe criteria for the height of the protected area in the case study of this research.

An Empirical Modelling and Simulation Framework for Fire Events Initiated by Vegetation and Electricity Network Interactions

Electrical infrastructure is one of the major causes of bushfire in Australia alongside arson and lightning strikes. The two main causes of electrical-infrastructure-initiated fires are asset failure and powerline vegetation interactions. In this paper, we focus on powerline–vegetation interactions that are caused by vegetation falling onto or blowing onto electrical infrastructure. Currently, there is very limited understanding of both the spatio-temporal variability of these events and their causative factors. Bridging this knowledge gap provides an opportunity for electricity utility companies to optimally allocate vegetation management resources and to understand the risk profile presented by vegetation fall-in initiated fires, thereby improving both operational planning and strategic resource allocation. To bridge this knowledge gap, we developed a statistical rare-event modelling and simulation framework based on Endeavour Energy’s fire start and incident records from the last 10 years. The modelling framework consists of nested, rare-event-corrected, conditional probability models for vegetation events and consequent ignition events that provide an overall model for vegetation-initiated ignitions. Model performance was tested on an out-of-time test set to determine the predictive utility of the models. Predictive performance was reasonable with test set AUC values of 0.79 and 0.66 for the vegetation event and ignition event models, respectively. The modelling indicates that wind speed and vegetation features are strongly associated with vegetation events, and that Forest Fire Danger Index (FFDI) and soil type are strongly associated with ignition events. The framework can be used by energy utilities to optimize resource allocation and prepare future networks for climate change.

Lightning strike damage behavior of zirconium carbide and copper modified short-carbon-fiber-reinforced boron phenolic resin composites under 200 kA

By using artificial lightning of standardized Waveform A, this study explored the lightning strike protection (LSP) effect of zirconium carbide (ZrC) and copper (Cu) modified short-carbon-fiber-reinforced boron phenolic resin composites under a current peak of 200 kA. Based on the results of visual observation, micro-morphologies characterization, three-dimensional shapes and X-ray detection, we observed a remarkable LSP effect in this composite, which can be attributed to the high bending strength of the laminated structure, and the well thermal resistance of ZrC. Meanwhile, the addition of Cu powders with concentrations of 10% was demonstrated to enable efficiently withstand the lightning strike and prevent crack propagation since the electrically conductive path. Our findings proposed a promising LSP skin material for the aircraft, which will maintain structural stability under the impact of a lightning strike.

Integrated Model for Lightning Strikes on a Tall Structure: Application to a Wind Turbine System

This article presents an integrated model of the lightning channel and tall structure on the ground for lightning analysis, by considering their interaction. An extended distributed circuit is proposed for modeling the lightning channel, by including the dynamic behavior of the corona sheath. The nonlinear, nonuniform, and time evolution characteristics of the lightning channel are taken into account. Meanwhile, the wire structure on the ground is modeled with the partial element equivalent circuit method. A lumped voltage source is introduced to ensure an “undisturbed” current waveform at the attachment point. A procedure is provided to determine this voltage source in a nonlinear circuit. The proposed model is verified with the experimental data of lightning-striking tall towers. This model then is applied to simulate lightning surges on a wind turbine system. A comparison with the simple current source model is made. Significant oscillation is found with the simple current source model, which is not in correspondence with the observation result under natural lightning.

A study on the effects of electromagnetic coupling mechanisms in the event of an indirect lightning strike near photovoltaic arrays

Indirect lightning strikes hitting near photovoltaic installations are much more frequent than direct hits, and can generate overvoltage in their electric circuitry. The authors developed a method to estimate the induced overvoltage on single photovoltaic modules. Using a model of the whole array also including Inter-Module Coupling Mechanisms (IMCMs), a new approach to estimate overvoltage induced on full arrays is presented in this paper. The procedure first estimates lumped parameters, modelling either the coupling between the lightning channel and each module in the array or between each couple of modules in array. Several circuital simulations are then run using suitable equivalent circuits. The aim is to consider different array configurations and groundings schemes. This allows extracting the most relevant configuration parameters influencing overvoltage/overcurrent. Results show that the groundings scheme impacts negligibly, but the single module electric stress is decreased by 35% in the case of ungrounded configurations. Among the considered array configurations, the honey-comb and total cross-tied showed the smallest impact on overvoltage. Statistical analysis on random LC tortuous geometry leads to a non-negligible rise of overvoltage peak values, up to 24%. Finally, the relevance of different IMCMs is analysed, showing a strong impact just on frame-ground voltages and currents.

The Impact of Transmission Line Modeling on Lightning Overvoltage

In most of the work that investigates the backflashover phenomenon due to direct lightning strikes, using EMT-type simulators, transmission lines are represented by the J. Marti model and the ground effect is computed employing J. R. Carson’s formulations. Thus, the ground displacement current is neglected, the line voltage definition corresponds to the wire potential formulation, and soil resistivity is considered frequency-independent. These considerations can lead to erroneous measurements of the occurrences of the backflashover phenomenon in the insulator strings of transmission line. In this sense, this paper presents a systematic sensitivity analysis study of lightning overvoltage in insulator strings considering more physically consistent models of the transmission line, which consider the displacement current, ground admittance correction, rigorous voltage definition, and frequency-dependent soil parameters. According to the results, for the case study, transmission line parameters modeling can present a maximum percentual difference of around 71.54%, considering the frequency range of first strokes. This difference leads to a percent difference of around 5.25% in the maximum overvoltage across the insulator strings. These differences confirm that the occurrence or not of backflashover in the insulator strings, including the disruption time, are sensitive to the line model considered.

Developing Test Methods for Compression after Lightning Strikes

Research into residual strength after lightning strike is increasing within the literature. However, standard test methods for measuring residual compressive strength after lightning strikes do not exist. For the first time, a systematic experimental study is undertaken to evaluate modifications necessary to standard Compression After Impact (CAI) specimen geometry and test jig design to induce specimen failure at the lightning damage region. Four laboratory generated lightning strike currents with peak amplitudes ranging from 25 to 100 kA have been studied. Test set-up modifications were made considering the scale of the lightning damage and its potential proximity to specimen edges. Specimen geometry and anti-buckling guides were adjusted for each peak current to induce specimen failure at the lightning damage. The Compression After Lightning (CAL) strength was 28% lower than the pristine CAI strength even at a relatively low peak current of 25 kA. This study shows that the standard CAI test setup has the potential for CAL application, however, careful modifications are required depending on the peak amplitude of the applied lightning current waveform.

Lightning Prediction Using Electric Field Measurements Associated with Convective Events at a Tropical Location

Nowcasting of lightning occurrences is essential in tropical locations as lightening causes severe damage to life and property. This study attempts to nowcast lightning events during convective phenomena using an electric field monitor (EFM) at a tropical urban location, Kolkata (22.65°N, 88.45°E). Before the onset of heavy lightning occurrences, definite changes in the atmospheric electric field (EF) are observed, which in turn are associated with high cloud liquid water content (LWC) and low cloud base height (CBH). A model has been proposed to nowcast lightning strikes within about 17.5 km radius of the present location based on the EF standard deviation (EFSD) values. The proposed technique is tested with the lightning data provided by a collocated lightning detector, which yields a prediction efficiency of ~ 0.91 (~ 0.86), a false alarm rate of ~ 0.23 (~ 0.18), and a critical success index of ~ 0.71 (~ 0.72) with an optimal range of other performance parameters during the monsoon (pre-monsoon) periods, thereby generating an alarm 45 min before lightning events.

Observation and Simulation of Lightning Strikes in an Off-shore Wind Turbine Cluster

Observation and Simulation of Lightning Strikes in an Off-shore Wind Turbine Cluster

Enhanced through-thickness electrical conductivity and lightning strike damage response of interleaved vertically aligned short carbon fiber composites

Through-thickness electrical conductivity of carbon fiber reinforced polymers (CFRPs) is a key characteristic that determines the severity of lighting strike-induced damage. Carbon Fibers (CFs) are inherently electrically conductive and therefore provide high conductivity in the direction of the fiber orientation. However, electrical conductivities through the thickness and orthogonal to the CF orientation in CFRPs are governed by the insulating polymer matrix present between CFs. In this work, through the thickness alignment of short CFs in between layers of CFRP laminates is demonstrated to improve the through-thickness electrical conductivity. Composites with interleaved vertically aligned short CF fibers (<150 μm) will be referred as V-fiber composites hereafter. The effect of the V-fiber on the lightning strike damage is evaluated against an artificial lightning strike of 100 kA (modified waveform A of SAE ARP-5412B standard). The improved through-thickness electrical conductivity of CFRP laminates (1.15 S/cm) through vertical alignment of short CFs was compared to reference CFRP laminates (0.13 S/cm) and was found to dissipate the artificial lightning strike current more efficiently. The surface damage after the artificial lightning strike in the V-fiber composites was reduced to 12.69 cm2 compared to the reference CFRP surface damage of 57.67 cm2, a 78% reduction. It was also demonstrated that Joule heat generated due to lightning strike on the composites was significantly less than the reference sample using infrared (IR) thermography. A high retention (up to 78%) of flexural properties (modulus and strength) was observed in V-fiber composites post lightning strike impact as compared to only 47% retention in the reference panel.

Probabilistic impact assessment of lightning strikes on power systems incorporating lightning protection design and asset condition

Lightning strikes may result in widespread power outages with long supply interruption times and severe impacts to economy and society. To prevent this from happening now and in the future, power system planning and operation practices must be revisited so that the probability of outages caused by lightning strikes can be reduced. In this context, this article presents a probabilistic framework for impact assessment of lightning strikes on the grid which investigates power system exposure to lightning strikes. This new framework incorporates information about failure rates attributed to lightning protection system design and asset condition together with the probability of lightning activity over time for a probabilistic impact assessment of lightning strikes on the grid. Notably, the probability of lightning activity is conditioned by information about weather patterns and seasons obtained through collaboration with the Met Office. Furthermore, it is demonstrated in the reduced 29-bus Great Britain transmission system model with weather data collected from 2010 to 2019 and validated against historical fault data recordings provided by the National Grid’s Transmission System Performance Reports and by the National Fault Interruption Reporting Scheme. Therefore, the framework is envisaged to assist power system planners to investigate best design and maintenance practices and grid modernization interventions and power system operators to deploy smart operational measures that reduce the probability of power outages caused by lightning strikes.

Predicting the Class of Salt Contamination for Wind Turbine Blade under a Lightning Strike Using Fuzzy Inference System and Probabilistic Neural Network

This study predicts the class of salt contamination for wind turbine blades that undergo a lightning strike using a fuzzy inference system (FIS) and a probabilistic neural network (PNN). The experiment uses four classes of equivalent salt deposit density to determine the salt contamination status for a wind turbine blade. The greatest degree of salt contamination is 338.9 µg/cm2. The rotational speeds of the blades are set as 0, 50, 100, and 150 rpm. Many lightning strike surge experiments are conducted for different types of salt-contaminated blades. The lightning current signals in the grounding line are measured using a high-frequency current transformer. This study uses an experimental method to determine the effect of salt contamination on wind turbine blades during lightning strikes. In terms of prediction, FIS and PNN are used to predict the four classes of salt contamination. The peak absolute value and the average power of the measured signals are the input datasets for the FIS and the PNN. The predictions for the ESDD classes are 94.8% for a FIS and 88.8% accurate for a PNN. The research results show that the proposed method accurately predicts the salt contamination class for wind turbine blades.

Simulation of Cloud-to-Ground Lightning Strikes to Wind Turbines Considering Polarity Effect Based on an Improved Stochastic Lightning Model

The accurate determination of the annual lightning flash number to a wind turbine is essential for designing proper lightning protection measures. However, the method to assess the lightning risk of wind turbines recommended by the IEC is not associated with the actual lightning attachment process. Additionally, there is little research on positive cloud-to-ground (+CG) lightning. In this study, a lightning risk assessment method correlated with wind turbines on the basis of an improved stochastic lightning model is proposed. Based on the model, the influence of the lightning current amplitude, wind turbine heights and blade rotations on lightning strike risk are quantitatively analyzed. Moreover, the development and distribution characteristics of negative cloud-to-ground (−CG) lightning and +CG lightning are discussed. Finally, a more accurate calculation method of lightning strike risk is proposed considering the polarity effect. The results show that the effect of blade rotations on lightning risk cannot be ignored when the lightning current is large or when the wind turbine is tall. The −CG lightning has more bifurcation, but the dispersity of its development path and the lightning strike point are both small. The +CG lightning has scattered lightning strike points, and the development paths are tortuous, and. According to the verification calculation, the results calculated in this paper are in better agreement with the observation data than the results calculated by the IEC (International Electrotechnical Commission) recommended method.

Influence of photovoltaic support on lightning transient under direct lightning strike

• A new transient circuit model for calculating the transient response of PV support is developed. • The transient overvoltage caused by the mode of air-termination rod and lightning strike point are investigated. • The influences of additional leg, tile angle and equipotential bonding have been studied. • Four types of PV supports are chosen and their lightning transient responses under direct lightning strike are comprehensively investigated. Due to the large-scale installation of photovoltaic (PV) plants in open areas, PV plants is exposed to lightning strike at a high risk. The influence of PV support on lightning transient under direct lightning strike is investigated in this paper. Firstly, the PV support composed of multiple branches is classified into vertical conductor, horizontal conductor and oblique conductor. Their wave impedances are individually derived. Considering the air-termination rod and earthing system, four types of PV supports are chosen and their lightning transient responses under direct lightning strike are comprehensively studied. It suggests that the transient response is heavily dependent on the number of grounding legs. The greater the grounding legs, the lower the overvoltage. The equipotential bonding provides additional routes for the discharge of lightning current. Its presence would minimize the voltage but increase the risk for the entire PV system. The additional auxiliary leg also plays a role. The non-isolated air-termination rod is suggested install at the symmetrical center of the PV support from the perspective of discharging the lightning current.

Forensic-medical examination by the Van Forensic Medicine Group Directorate to deaths as a result of lightning strike

Lightning strikes may be a cause of death for farmers, sailors, and those engaged in outdoor sports. Death occurs due to damage to the cardiovascular and central nervous systems. In the autopsies performed in cases of lightning strikes, the information about the location of the incident, sociodemographic data, regions of burns and injuries on the body, histopathological findings, and cause of death are examined. In this study, a retrospective evaluation was made of 7 cases for which an autopsy was performed because of lightning strike in the city of Van in eastern Turkey. The deaths were seen to have occurred most often in spring, in the month of May. The 7 cases comprised 85.7% males and 14.3% females with a mean age of 28 years, and all were injured while shepherding. In 2 cases there was a witness, and in 6 cases, there were found to be burns and tears in the clothing. Singeing and flattening of the body hair was seen most often in the chest region. In addition to the findings of lightning strike, there were accompanying findings of blunt trauma (grazes, ecchymosis, lacerations) in 4 cases. There were first and second-degree burns in all the cases, with a mean 11.6% burned surface area. Histopathologically, focal subarachnoidal fresh bleeding was seen in 2 cases, subpleural and intra-alveolar fresh bleeding in the lungs in 2 cases, and interlobular rupture in the lungs in 2 cases. It must not be forgotten that lightning strikes are an uncommon natural catastrophe but have a high mortality rate. Together with the non-specific autopsy findings, examination of the scene of the incident and witness statements will be able to support the determination of the cause of death.

A Rare Case of Fatal Lightning Strike in Dammam with Unusual Cutaneous Findings

Determining the cause of death in lightning strikes could be easily reached if the circumstances were witnessed or if typical kerauno-pathologic features were found on the body. However, in rare cases, certain unusual skin features are found, which makes attribution to the cause of death more difficult, especially if unwitnessed. In this case, a witnessed lightning strokes a 42-year-old male while he was walking outdoors in a rainy day, leaving him with a rare finding of punctuate burns over the back of the body (crocodile skin) and nonspecific internal organ findings. The clothes were burnt and shredded, and the hair of the affected area was singed. Rare findings of lightning strikes need to be reported as they can be the key in leading investigations in unwitnessed strikes.

Modelling the daily probability of lightning-caused ignition in the Iberian Peninsula

Background Lightning is the most common origin of natural fires, being strongly linked to specific synoptic conditions associated with atmospheric instability, such as dry thunderstorms; dry fuels are required for ignition to take place and for subsequent propagation. Aims The aim was to predict the daily probability of ignition by exploiting a large dataset of lightning and fire data to anticipate ignition over the entire Iberian Peninsula. Methods We trained and tested a machine learning model using lightning strikes (&gt;17 million) in the period 2009–2015. For each lightning strike, we extracted information relating to fuel condition, structural features of vegetation, topography, and the specific characteristics of the strikes (polarity, intensity and flash density). Key results Naturally triggered ignitions are typically initiated at higher elevations (above 1000 m above sea level) under conditions of low dead fuel moisture (&lt;10–13%) and moderate live moisture content (Drought Code &gt; 300). Negative-polarity lightning strikes (−10 kA) appear to trigger fires more frequently. Conclusions and implications Our approach was able to provide ignition forecasts at multiple temporal and spatial scales, thus enhancing forest fire risk assessment systems.

Lightning Protection of Buildings: Its Types, Solutions and Choice Options

Abstract Lightning safety in private and public buildings is a seriously evaluated issue that requires an appropriate and safe long-term solution to protect property from destruction during or due to the consequences of a lightning strike. Relatively easy-to-replace home appliances such as a TV-set or a vacuum cleaner, larger and more expensive appliances such as a heat pump, alarm system or antennas can be damaged from a lightning strike. The aim of the study is to explore the ways of lightning protection in buildings and to develop recommendations for its effective use. Lightning protection is part of a set of electrical assembly and fire protection measures of property, which are performed during construction or renovation of property and the installation thereof is determined by the regulatory framework of the Republic of Latvia. Over time, two types of lightning protection systems have been developed: the classic or passive lightning protection system, which, if hit by lightning, captures and drains the electrical charge generated by lightning to the ground, and the active lightning protection system, which attracts the electricity generated by lightning with energy generated by itself and then drains the charge to the ground. Consequently, both lightning protection systems can be considered to have their advantages and disadvantages, so it is necessary to assess the choice of the most appropriate protection system on a case-by-case basis, also taking into account the criteria such as the complexity of the building project, the size and accessibility of the protected area and the cost of each individual site.

Studying Direct Lightning Stroke Impact on Human Safety Near HVTL Towers Considering Two Layer Soils and Ionization Influence

A lightning strike is considered one of the most risky natural phenomena that can lead to human harmful and the surrounding soil layers. To tackle this issue, this article investigates the influence of direct lightning characteristics in terms of human body safety. Specifically, such investigation is carried out on the effect of resistivities of two-layer soils on human safety when lightning stroke hits the towers of the high voltage transmission lines (HVTLs). The merit of the proposed study is that the soil ionization phenomenon is taken into consideration. Further, the study focuses on the current passing through the human heart, when step and touch (contact) voltages are generated by grounding potential rise, caused by direct lightning strikes transmission tower and the produced potential rise that a person could be exposed. Also, studying the effects of peak current and time of lightning strokes are investigated. Additionally, the paper presents the effect of different reflection factors on human safety. For validation purposes, the ATP program is used in the simulation of the grounding system as well as the human body model. Numerous simulations were accomplished in order to examine the behavior of the current passing through with the human heart. Based on the simulation results, it was concluded that the soil characteristics have superior influences on the contact and step potentials and, accordingly, the survival threshold.

A Novel Transient Model of Photovoltaic Module Considering Electromagnetic Coupling

Photovoltaic (PV) arrays are threatened by lightning strikes due to the wide-open installation area. Lightning surges can not only damage the insulating structures of PV modules but also reduce the efficiency of a cell. Considering the electromagnetic coupling between the PV-cell string and the metal frame, a novel transient model of PV module is developed in this article. The proposed model is compared with the method of moments and validated by the previous experimental results. The effect of PV-cell wiring on lightning-induced voltage is comprehensively analyzed. The result indicates that the induced voltage of PV module is determined by the impulse magnetic field. The wiring scheme has a great impact on the induced voltage since it changes the area of the loop. The lightning overvoltage between the PV module and the bracket can be reduced by the use of an additional down conductor. The proposed model is more comprehensive and efficient than previous studies. It can be used to evaluate the induced voltage of PV module and predict the failure mode of the bypass diode caused by a lightning strike.