LIGHTNING is the main factor of outage and insulation breakdown of power system. The LIGHTNING event can produce dangerous overvoltage, equipment failures, and power supply interruption. In this paper, externally gapped Line arresters (EGLAs) performances have been investigated to evaluate the LIGHTNING performances of a typical 63 kV transmission line. A probabilistic analysis has been done to study the EGLA performance in transmission line by Monte-Carlo method. The results show the EGLA performance dependency to soil resistivity and LIGHTNING strike parameters.

LIGHTNING strikes that directly hit the wind turbine will probably attach to the blade could cause excess structural damage. The blade and hub usually represent around one fourth of the cost of a large modern machine and may be the most expensive components to replace. The blade is not only the link between wind energy and the mechanical energy going to the gearbox, but could be a LIGHTNING link to all the equipment associated with the wind turbine. In this paper a model of LIGHTNING channel progression towards the earth is given based on physics of discharge of cloud. The physical assessment of the electric field is done with the charge simulation method which is adopted to describe into MATLAB software the parameters which are involved in the progression of the negative downward channels towards the earth and in the inception and propagation of upward positive channels from earthed structures. The method and results can be used for designing LIGHTNING protection system of wind turbine.

The produced electric and magnetic fields due to LIGHTNING strikes to mountainous ground are determined in this paper. For the sake of simplicity a cone-shaped ground with finite conductivity is assumed to represent a natural nonflat ground. By this assumption, we deal with an axillary symmetrical structure so we use the cylindrical 2D-FDTD to save the simulation memory and time, dramatically. The return stroke channel is modeled using the antenna theory model with fixed inductive loading (ATIL-F) which is appropriately incorporated into the FDTD algorithm. We have derived the updating equations of 2D-FDTD for distributed resistance and inductance in ATIL-F model. Both the first and the subsequent return strokes are considered and their related radiated electromagnetic fields are determined and compared with each other. The fields are calculated at an intermediate horizontal distance from the cone-axis.The calculated results show that the presence of the cone-shape ground introduces an enhancement in electric and magnetic fields, for both first and subsequent return strokes. Since sharper lossy cone means larger current density in the ground, the increment in the amplitude of the fields is inversely proportional to the cone-angle. A hump is observed in electromagnetic field waveforms because of the current reflection form joint point of the cone-shape ground and the flat ground beneath it. It is more specific in the subsequent-stroke fields. simulation results for different cone-height are presented. It shows that for small values of height, the results approaches to thoseof the flat ground.

A new type of closed-type LIGHTNING protection multi-chamber arrester named impulse quenching line LIGHTNING protection device (LLPD) used for protection of overhead power lines is described. After the passing of LIGHTNING current, the multi-chamber system of the arrester prevents the occurrence of a network short-circuit current due to the total voltage drop across several thousand series-connected spark gaps that significantly exceeds the applied network voltage in magnitude. The total operating time of the LLPD is less than 1 ms which is not sensitive for microprocessor and relay protection of overhead lines. A computational estimation of the emergency outage rate of double-circuit overhead power lines without an overhead ground wire resulting from LIGHTNING overvoltage was carried out. Number of current impulses used when arresters are tested for quenching capacity as well as their parameters were determined by the mathematical modeling using the statistical Monte Carlo method. Results of calculation that make it possible to determine the efficiency of LIGHTNING protection of double-circuit overhead lines with various placement schemes of the line LIGHTNING protection device LLPD-110 of the company Streamer Electric AG are presented in the conclusion.

Wind turbines, because of their height and localization, are frequently subject to direct LIGHTNING strikes. Thus, the investigation on the performance of their grounding system is of paramount interest for the prediction of the potential threats either for people working in (or animals passing through) the wind farm area and for the power and control units installed in close proximity of the turbine towers. In this paper, we perform a comprensive study of the transient behavior of the earthing systems of wind turbines. The analysis is conducted in the frequency domain and an hybrid approach, based on circuit theory and Method of Moments, is adopted to fully account for resistive, inductive and capacitive couplings between elements of the ground system. The actual transient behavior is obtained by means of an Inverse Fourier Transform. The results, computed considering a typical wind turbine grounding system configuration, provide more insight on the nature of the early-time transient response of grounding systems and allow to draw up useful design guidelines.