This paper investigates the overvoltage stress distribution in transformer bushings subjected to high-frequency electromagnetic transients, such as lightning impulses. A comparative simulation approach was implemented using COMSOL Multiphysics to analyze both real and perfect conductor configurations of the bushing. The study applies a lightning impulse waveform to evaluate electric field behavior along the bushing structure. Results show that conductor geometry and internal foil arrangement significantly influence field intensity, with localized stress concentrations emerging before the onset of dominant skin effect. Additionally, the output pulse exhibits a damping effect, indicating energy dissipation over time due to bushing impedance characteristics. These findings provide insights for improving insulation coordination, optimizing bushing design, and enhancing surge protection strategies in high-voltage power systems.

The growing use of renewable energy in microgrids introduces uncertainty due to the variable nature of wind and solar generation. This study evaluates the reliability of a benchmark low-voltage microgrid using a probabilistic framework based on Monte Carlo Simulation and statistical modeling of load demand, wind speed, and solar irradiance. System adequacy is assessed using the Expected Energy Not Served (EENS) index. Three mitigation options are examined under the same stochastic conditions: installation of a micro-turbine with renewable curtailment, implementation of demand-side management (DSM), and integration of energy storage. A ten-year economic comparison is also performed to assess long-term feasibility. The results show that renewable generation alone does not fully eliminate supply shortages. DSM reduces deficits effectively with relatively low investment, while the micro-turbine improves reliability at higher capital cost. The contribution of energy storage depends strongly on installed capacity, and under the considered rating, its impact is limited during prolonged deficit periods. The study provides a consistent technical and economic comparison of alternative strategies for improving reliability in renewable-based microgrids.

The impact of inductance and skin effect in multilayer coaxial cables on the transient behavior of transformer bushings is studied in this paper. The transient behavior caused by lightning impulse is studied by creating an axisymmetric model with COMSOL Multiphysics. The research examines self and mutual inductance and shows how skin effect changes as the frequency is altered. The structure's coaxial design is similar to a bushing, letting us analyze how electromagnetic waves reflect, fade and connect or not connect to another material. Connecting circuits are analyzed using numerical and analytic methods to find their inductance and surface current distributions. Analysis shows that the results are controlled by inductance and the skin effect, proving that an oversimplified cable model is a viable technique for looking at bushings under sudden high voltages.