Mar 31, 2016 assume i f in equation 22 is described by a double exponential, equation 28 using the values determined for g 1, g 2, g 3, g 4 and g t, and assuming the lightning stroke lightning is the median 30 ka 5. The amplitude and steepness of the current impulses were varied in. Results figs 47 depict the developed overvoltage at the entrance of the transformer in function with the grounding resistance and the installation position of. Ftip, where ltip is the distance between the location of the force sensor and the icor of the mcp joint. A doubleexponential lightning current function suitable for. Curve fitting with double exponential equations 4803. Most lightning currents show the negative polarity. Effect of multiple lightning strokes on clamping spds. A double exponential function red curve compared to a single exponential function blue curve. The impulse current or short stroke typically has a double exponential waveform of which the rise time can be as short as a fraction of a microsecond which results a maximum time derivative. A mathematical modeling of double exponential voltage. Fitting a double exponential cumulative distribution function. Introduction in the field of electromagnetic analysis of lightning phenomena a number of mathematical functions are available for modelling the channelbase.
Request pdf a doubleexponential lightning current function suitable for use of different sets of input data a function to simulate lightning return stroke current as a sum of two exponential. Predict what may happen on a given installation and recommend solutions for improvement. The assumption is grounded in the property that the asymptotic distribution of the maximum of n independent, identically distributed random variables is the double exponential when the underlying distribution has an upper exponential tail. Curve fitting with doubleexponential equations 4803 3. Rtca do160f lightning testing the world leader in serving science overview, updates, changes and whats coming next. Generation of variable outputs impulse generator can be designed by combination of flyback transformer and marx generator which can produce different high voltages. Comparison between heidler function and the pulse function. The pdf for such a construct is given by 12 12 1 double exponential pdf xx ee. A lightning waveform is usually defined by the rise time t f, pulse length t p and peak. Parameters affecting lightning backflash over pattern at. A novel approach for developing a closedform solution for the magne tic field from the indirect effect double exponential current waveform will be presented.
Comparison between heidler function and the pulse function for modeling lightning returnstroke current master of applied science, 2010 khaled elrodesly electrical and computer engineering ryerson university in the past, many functions were considered for simulating the lightning returnstroke current. Lightninggenerated fields in reinforced concrete buildings. It is a composite of a single exponential moving average, a double exponential moving. The model 93541 and 93542 transient generators provide nine selectable waveforms, including six damped sinusoidal pulses 10 khz, 100 khz, 1 mhz, 10 mhz, 30 mhz, and 100 mhz and three double exponential pulses 6. Defense dod has incorporated the double exponential current waveform as part of their. By approximating the variable dependent exponential terms, we were able to minimize the complexity of the mathematics required to solve for the magnetic field in closedform. This allowed engineers to study the effects of the lightning postarcing. Comparison of simulation tools atpemtp and matlab simulink. Esd test waveform the exponential rise time of lightning is in the range 1.
The do160e lightning induced voltage waveform 3 damped sinusoid and voltage waveform 4 6. Double exponential equations can be tried when easier forms like straight lines, parabolas, hyperbolas, and single exponential equations are not satisfactory. A double exponential lightning current function suitable for use of different sets of input data abstract. It is also sometimes called the double exponential distribution, because it can be thought of as two exponential distributions with an additional location parameter spliced together backtoback, although the term is also sometimes used to refer to. Triple exponential moving average tema definition and. This effect can be modelled by a negative triple exponential.
New functions for representing iec 62305 standard journal of lightning research, 2012, volume 4 51. Double exponential and heidler function are the two mathematical expressions for lightning current waveshapes and widely used in studying the effects of lightning. This is a secret ichimoku indicator, widely used in japanese trading rooms. Statistics and machine learning toolbox also offers the generic function pdf, which supports various probability distributions. They give a physical model of the lightning, which is. For those who are new to the requirements, many questions are left unanswered. The pulse durations are much longer than damped sine.
Tower lightning returnstroke current, including the double exponential and jones modified double exponential functions. The research into lightning current waveforms was initially started in 1941 by bruce and golde 15. A new method for deriving the magnetic field induced by a lightning strikes indirect effect double exponential has bee n presented. The lightning current is given by a double exponential equation. Application of line surge arresters in power distribution and.
Lightning is a natural phenomenon, which generates simple unidirectional double exponential impulses, which has a significant effect on power transmission system and equipment. Using this property, yellott proposed a thought experiment in which there are three basic alternatives. If you hear the sound of thunder, then you are in danger from lightning. Lightning critical flashover voltage of high voltage. In order to represent lightning current waveforms in an analytic manner, the double exponential formula is employed to fit with the lightning current waveforms. It i0 e at e bt ut 1 where b 647,265 sec1, a 11,354 sec1, i0 is 218,810 amps, which gives the peak double exponential amplitude of 200ka, and ut unit step function.
The exponent of the first term is a linear function of time, while the exponent of the second. Double exponential, impulse generator, transient condition. Bruce and golde used it not only for the first, but also for subsequent strokes. The types of pulses used in surge and lightning testing include double exponential style pulses and damped sine wave pulses. Design and fabrication of a high voltage lightning impulse. Also, since they are not oscillatory, the components exposed to the pulse are experiencing a flow of charge in one. Lightning parameters iec norms provide a precise formula for the time domain waveform i1t2of the stroke current, which is different from the usual double exponential, avoiding a singularity at the curve startup, whereas the exponential would rise from a null to a finite slope in a zero time interval 1. I used the code to fit your data to over two hundred known equations with three or less parameters, and chose this one from the sorted results. Different mathematical expressions have been used since that time to describe the lightning current waveform and the double exponential expression is used. Probability density function the general formula for the probability density function of the double exponential distribution is. Do160e recommends waveform 4 for airborne equipment that may be subjected to lightninginduced magnetic fields coupled onto their wiring. This paper describes the relationship between the waveform parameters t f, t p, i and the formula constants alpha, beta and a. It represents the statistics of two exponential probability events each with a separate shape or beta parameter. The functions are derived from the normalised lightning impulse voltage where the double exponential function is scaled in the time direction so that the number of parameter presenting the function is reduced from two to one, making then treatment of the function much easier.
Develop a new formula which describes the magnetic field induced by a lightning strikes indirect effect double exponen tial current waveform. Pdf least squares estimation of doubleexponential function. A double exponential function fitting algorithm for optimize. By approximating the variable dependent exponential terms, we were able to minimize the complexity of the mathematics required. A doubleexponential lightning current function suitable. Lightning is a bright flash of electricity produced by a thunderstorm. Its long been something you had to either be in the know about or pay money to learn.
In order to represent lightning current waveforms in an analytic manner, the doubleexponential formula is employed to fit with the lightning current waveforms. Open access new functions for representing iec 62305. Probability density function the general formula for the probability density function of the double exponential distribution is \ fx \frace\left \fracx\mu\beta \right 2\beta \ where. Recovery of valuable incompletelyrecorded return stroke. During the time period of the lightning bolt, the noise is nongaussian and has much heavier. On the effect of lightning on a solar photovoltaic system. In the literature, models typically employ the pulse. Exponential distribution cumulative distribution function. To use pdf, create an exponentialdistribution probability distribution object and pass the object as an input argument or specify the probability distribution name and its parameters. Ab kadir centre of excellence on lightning protection department of electrical and electronics engineering universiti putra malaysia, malaysia abstractthis study investigates possible lightning threats to naval. High voltage induced by transmission lines due to lightning. The lightning waveform a is as follows in the time domain. I know that the integral of a pdf is equal to one but im not sure how it plays out when computing for the cdf. The lightning currents are measured on tall structures and by artificially initiated lightning.
Transient overvoltage calculation on the floating roof. Transient suppression for surge and lightning pulses. A new doji show episode will be uploaded to youtube shortly following the release of this indicator. On the other hand, heidler and the pulse functions. Impulse generator and lightning characteristics simulation. It has not been submitted before for any degree or examination to any other university. The magnetic field induced by a lightning strikes indirect effect. Lightning transient waveform 100% 90% i % i 10% 30n 60n tr 0.
Doubleexponential parameter determination for the lightning. A function to simulate lightning return stroke current as a sum of two exponential terms is presented. This article is intended to introduce the requirements of do160, section 22, and to address some of those fundamental questions. Probability density function the general formula for the probability density function of the double exponential distribution is where is the location parameter and is the scale parameter. Thus, the modeling of lightning phenomena has become a rather hotissue and it is now addressed as one of the major concerns of the distributors, material manufacturers, designers, or installers. Abstract this paper presents the method for calculation of lightning critical flashover voltage cfo of high voltage insulators. The magnetic field induced by a lightning strikes indirect. The current path for the lightning strike was simulated as contact with the statue rather than the formation of the lightning plasma arc. A mathematical modeling of double exponential voltage waveshape impulse generator for. A double exponential function is a constant raised to the power of an exponential function. Results for lightning electric and magnetic field at different distances from the channelbase obtained by using the proposed function and the modified transmission line model with exponential decay with height are in good agreement with the results from literature, but any other lightning stroke model can be used as well.
Double exponential lightning stroke current model a i. Lightning was modeled as a current source with a pulse shape commonly represented as a double exponential in time. Over the past few years, the standard rtcado160, section 22 has undergone multiple revisions. A mathematical modeling of double exponential voltage ijesi. Michael hopkins rtca do 160 rtca is the radio technical commission for aeronautics publishes do 160 latest is do 160f, issued in december 2007 and now available for downloading. A novel approach for developing a closedform solution for the magnetic field from the indirect effect double exponential current waveform will be presented. The lightning current was modelled as a double exponential impulse with a concave front, with varying values of amplitude and maximum steepness. Compared with the function from iec 623051, the proposed function offers slightly different front of the current impulse. All thunderstorms produce lightning and are very dangerous. Years ago i ran a online curve and surface fitting web site named, and this had a function finder with a genetic algorithm front end for initial parameter estimation.
In probability theory and statistics, the laplace distribution is a continuous probability distribution named after pierresimon laplace. A class of analytical functions to study the lightning effects. The effect of the reflected waves can be analysed on the basis of the voltage curves. High voltage induced by transmission lines due to lightning case study k. The lightning flash is substituted by a heidlertype surge current generator and a resistor norton generator. This paper reports 10 kv to 100 kv high voltage impulse generator. Doubleexponential parameter determination for the lightning impulse voltage. A technical indicator used for smoothing price and other data. Simulation of lightning characteristics using pspice software. International comparison of software for calculation of lightning.
Doubleexponential expression of lightning current waveforms. A lightning waveform is usually defined by the rise time t f, pulse length t p and peak value i. The case where 0 and 1 is called the standard double exponential distribution. The exponent of the first term is a linear function of time, while the exponent of the second term is a power function of time with. Rakov,fellow,ieee abstractfrom a survey of the literature on lightning char. Models 93541 and 93542 transient generators generators. Design and fabrication of a high voltage lightning impulse generator author. However, these functions were found to have problems due to their timederivative discontinuities heidler and cvetic, 2002. Exponential probability density function matlab exppdf. Flashover occurrence on overhead transmission line insulators for 110 kv, 220 kv and 400 kv networks was studied using the leader progression model lpm. This paper describes the relationship between the waveform parameters. The telecommunication lightning waveform is different from the power line waveform because a lightning strike into a large telecommunication cable is distributed, lightning threat to both power and telecommunication lines.
Lightning impulse voltage ut was simulated by using double exponential function. A calculation model of floating roof oil tank was set up, then the lightning current was fourier transformed in frequency domain. Applied voltage waveform for lightning impulse withstand voltage test is a double exponential function ke t. The protection of power substations against lighting overvoltage is a major concern for. The total passive moment due to joint stiffness is given by. An approximation to the heidler function with an analytical. Parameters of double exponential function were selected for standard lightning impulse voltage waveform t. Parameters affecting lightning backflash over pattern at 2kv double circuit transmission lines dian najihah abu talib 1,a, ab. The purpose of the simulator is to provide a relatively economical and simple lightning simulator for the indirect effects testing of fullsized advanced composite aerospace vehicles.
Introduction ightning is an electric discharge that occurs in the atmosphere between clouds or between clouds to ground. Double exponential an overview sciencedirect topics. Open access new functions for representing iec 62305 standard. In this paper, an algorithm for estimation of double exponential function parameters is presented, which is based on a similar algorithm applied on the heidler function 3. It is being submitted to the degree of master of science to the university of the witwatersrand, johannesburg. A typical lightning current waveform is shown in fig. A new method for deriving the magnetic field induced by a lightning strikes indirect effect double exponential has been presented. Applied voltage waveform for lightning impulse withstand voltage test is a double exponential function k. Effect of multiple lightning strokes on clamping spds with focus on movs introduction the existence of multiple strokes in a lightning flash has been known for a long time, going back at least to the work of schoenland in the 1930, as noted by karl berger in his 1967 paper 1. Cumulative distribution functions and probability density functions. A lightning stroke was injected in the top of the centre tower of the modelled line section.1473 2 299 1057 710 1184 988 1640 76 390 1642 1496 1376 706 992 1613 565 1225 735 512 1193 1604 231 1519 571 442 737 110 78 298 178 23 721 795 634 36