Ensuring the protection of all components within power SYSTEMs from lightning-induced overvoltage is crucial. The issue of power interruptions caused by both direct and indirect lightning strikes (LS) presents significant challenges in the electrical sector. In medium voltage distribution feeders, the relatively low dielectric strength makes them susceptible to insulation degradation, which can ultimately lead to failures in the distribution SYSTEM. Therefore, implementing effective protective measures against LS is vital for maintaining an acceptable level of reliability in distribution SYSTEMs. This paper presents an analytical assessment of LS-induced SYSTEM overvoltage through high-frequency modeling of components within a 20kV distribution SYSTEM. The study utilizes EMTP-RV software for precise component modeling, including the GROUNDING SYSTEM, surge arresters, and distribution feeders. Additionally, the operational impacts of protective devices, such as ZnO surge arresters, shield wires, and lightning rods, are evaluated to mitigate LS-induced overvoltage. A frequency GROUNDING SYSTEM is implemented using the method of moments (MOM) to analyze the GROUNDING SYSTEM's influence on LS-induced overvoltage. Furthermore, eight different scenarios are explored to assess the anti-LS capabilities of the 20kV distribution SYSTEM. Each scenario involves evaluating dielectric breakdown and overvoltage across the insulator chain while proposing suitable protective solutions. The results indicate that the absence of shielding wires and surge arresters leads to higher breakdown voltages, with the lowest breakdown voltage occurring when surge arresters are installed during LS events. Additionally, the use of a frequency GROUNDING SYSTEM, due to its accurate modeling, yields more precise results compared to a static resistor approach. The MOM simulation reveals a 50% reduction in breakdown voltage under the worst-case scenario, and overall overvoltage experiences a 2% decrease.

Photovoltaic (PV) SYSTEMs are susceptible to lightning strikes. In this paper, a new accurate and efficient electromagnetic transient (EMT) model of GROUNDING SYSTEMs (GSs) is presented. The proposed approach considers the impact of frequency-dependent (FD) modeling of GSs on the overvoltage values in PV SYSTEMs in time domain analysis. The proposed wide-band model is significantly accurate for various types of GSs (single-port and multi-port GSs) and models the frequency dependence of the soil electrical parameters based on experimental data (conductivity and relative permittivity). The proposed model can be implemented in time domain without any GS impedance matrix inversion, so it has less complexity compared to previous approaches. Most of the existing studies suffer from low accuracy in the PV SYSTEM modeling during lightning transients because of neglecting the effects of the mounting SYSTEM, metal frame, and mutual coupling, which are considered in the present work. The results demonstrate that the PV factors and frequency dependence of soil have a great effect on the PV SYSTEM overvoltages. The proposed model offers improved accuracy by covering the entire frequency range of interest. Additionally, it takes into account the mounting SYSTEM, metal frame, and mutual coupling in EMT analysis.

In this paper, the performance of the EGLA (Externally Gaped Line Arresters) and its impact on the back flashover rate of a 400 kV transmission line have been investigated. The frequency behavior of the GROUNDING SYSTEM and soil resistivity has been modeled. To analyze the EGLA performance in relation to the GROUNDING SYSTEM's frequency behavior, a rod-shaped GROUNDING SYSTEM model has been implemented. By placing the EGLA at different phases of the transmission line, the best scenario has been identified to minimize back-flashover occurrences. Furthermore, the performance of the frequency GROUNDING SYSTEM to that of the nonlinear GROUNDING SYSTEM has been compared. The results clearly indicate that using a nonlinear GROUNDING SYSTEM leads to higher back flashover rates compared to the frequency GROUNDING SYSTEM. Additionally, the EGLA absorbs less energy when connected to a nonlinear resistor compared to the frequency GROUNDING SYSTEM. It can be concluded that modeling the GROUNDING SYSTEM's frequency behavior using the frequency GROUNDING model provides more accurate results, especially in investigations related to power grid insulation coordination.

Power equipment are subjected to multiple shock voltages during their operations that are generally caused by a lightning strike, switching of electronic power devices, or transient voltages which across available in the power SYSTEM. These impulses have a frequency range from several kHz to several MHz, which take pulses at very short intervals in several microseconds. Also, the equipment experiences the peak voltage and subsequently peak currents than their nominal values. These variations in voltage and current values, in very short intervals, have destructive effects on these equipment insulated SYSTEMs as well as on the accuracy of measuring ground impedance. The primary purpose of this study is to investigate the effect of standard and non-standard voltage impulse on power transformers windings by considering the mutual induction of transformer windings. Furthermore In this paper, by applying lightning pulse on power transformer windings for different models of ground voltage distribution SYSTEM on different disks of transformer windings terminal (20/0. 4KV, 100KVA, 9 disks continuous winding) and the disks voltage are calculated as outputs in MATLAB/Simulink. In previous studies, the calculations were in the time domain, while in this study, the ground impedance was measured in the frequency domain. The simulation results show that considering the model RC and considering the mutual induction, the voltage distribution on the disks is higher than other models. This study provides functional information for improving the design of insulations that are installed between windings and core the results of the present research may lead to the minimization of the dielectric failures. Furthermore, the results of this study can be used in future studies about non-standard impulse voltages. This investigation can certainly lead to modifying available standards or creating new standards in power transformers.