An improved procedure for the return stroke current identification

Return stroke current remote sensing, based on solving an inverse ill-posed problem

“…Another alternative is to directly solve the integral equations with the help of the collocation method, using Cebâşev or Geigenbauer base functions [4], [5]. These models show generally accepted errors in the range of about 16 to 20% [2].…”

Evaluation of Lightning Current and Velocity Profiles Along Lightning Channel Using Measured Magnetic Flux Density

“…Therefore, in order to use measured currents in the lightning studies, simulation using current functions can be done where the function parameters are determined based on measured current and using numerical methods [2,3]. Likewise, the lightning current can be evaluated based on measured electromagnetic fields at a number of observation points at different distances with respect to a lightning channel using inverse procedure algorithms [4][5][6][7][8]. The comparison between the direct measurement method and the inverse procedure algorithms shows that the direct measurement methods can consider only a limited number of lightning occurrences while the inverse procedure algorithms can cover a wide range of lightning occurrences based on recorded electromagnetic fields that arise from these events.…”

“…However, experimental measurements show that the return stroke velocity is actually a height dependent variable that has an increasing trend over the first few metres of height along a lightning channel and a decreasing trend after passing a peak value [14,15]. On the other hand, some inverse procedure algorithms consider all the field components in the frequency domain while they can evaluate current values at a number of sample frequencies by settling on a known current model and assuming the velocity as a constant value along a lightning channel [4][5][6]16]. These algorithms have some limitations on the number of sensors and the radial distances from a lightning channel while the synchronization of the recorded data over a large number of field sensors at different distances from the lightning channel is complicated.…”

Evaluation of Lightning Return Stroke Current Using Measured Electromagnetic Fields

“…For the direct effect, lightning strikes a tower or a power line while an indirect effect is caused by lightning striking the ground or any object around a power line and a voltage will be induced on the power line by coupling between the electromagnetic fields of the lightning and the line conductors. Several studies have been completed to evaluate the return stroke current which can be categorized into two groups; i.e., direct measurement of the current [1] and inverse procedure algorithms based on measured electromagnetic fields for the determination of the return stroke current [2,3]. In the direct measurement method, the current can be measured by setting current coils at the top of towers or by using the artificial triggered lightning technique to measure channel base currents [1,[4][5][6].…”

“…Different methods are available to evaluate the current although some of these methods only consider the fields measured at a far distance from the lightning channel and ignore the electrostatic and induction components of the fields [7][8][9][10][11][12]. Furthermore, some methods evaluate the current by using measured fields that are recorded up to intermediate distances from the lightning channel [3,[13][14][15], although they can only determine the current values at only selected sample frequencies The current model is a basic assumption in these methods. In this study, a general algorithm for the evaluation of the return stroke current using measured electromagnetic fields is proposed which considers the different field components unlike the previous methods.…”