Showing 4 results for Overvoltage
A. Tavakoli, A. Gholami,
Volume 7, Issue 3 (9-2011)
Abstract
Gas-insulated substations (GIS) have different specifications in proportion to air-insulated substations. Transformer failures related to lightning and switching are often reported in the gas insulated substation (GIS). This problem is the voltage magnifications due to reflections of switching and lightning surges at various junctions within the GIS. thereby overvoltages in GIS are more important than air-insulated substation. There are methods to suppress the stresses created by lightning and switching. However, these methods are suitable before installing the substation and during the substation design period. This paper presents feasible methods for mitigation of the overvoltage magnitude. The advantages of the proposed methods are their simplicity and low cost for implantation along with producing minimal changes in the installed GIS.
M. Khodsuz,
Volume 18, Issue 2 (6-2022)
Abstract
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.
Aida Gholami, Masume Khodsuz, Valiollah Mashayekhi,
Volume 21, Issue 1 (3-2025)
Abstract
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.
Peyman Gholami, Nabiollah Ramezani, Faridoddin Safaei,
Volume 22, Issue 3 (9-2026)
Abstract
This study investigates overvoltages transmitted through low-voltage (LV) networks, which pose a significant risk to sensitive electronic devices. High-frequency component models of the LV network are employed to analyze overvoltages propagating through LV distribution transformers. To efficiently assess these transients, the Monte Carlo method is applied, enabling a focused analysis within a constrained simulation domain while reducing computational time. Furthermore, a protective algorithm is proposed to safeguard LV networks and connected loads against lightning-induced overvoltages. The study also evaluates the influence of significant mitigation measures, including spark-gap-based protection and the installation of surge protective devices (SPDs), on overvoltage suppression in LV distribution systems. Finally, the effects of lightning strikes on the load-side lightning protection system (LPS) and the resulting induced overvoltages in the LV network are investigated. The proposed network and its components are simulated using both MATLAB and ATP-EMTP to ensure comprehensive analysis. In addition to the computational efficiency achieved through the enhanced Monte Carlo method, the proposed methodology offers a practical and effective approach for improving overvoltage protection in LV distribution networks.
