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High-voltage transmission lines are the backbone of modern power systems, facilitating the delivery of electricity from diverse generation sources, including conventional power plants and renewable energy systems, to consumers. As the electricity demand grows, the expansion of transmission infrastructure becomes essential to connecting new consumers with power suppliers. However, traditional transmission lines require significant right-of-way, posing challenges related to land use and environmental impact, as well as limited loadability. To address this issue, compact unconventional High Surge Impedance Loading (HSIL) transmission lines offer a viable solution by reducing right-of-way requirements while enhancing line natural power, mainly leading to less voltage drop. Before the implementation of the new unconventional HSIL lines, it is crucial to assess key parameters, such as magnetic field distribution under the lines, to ensure compliance with environmental and safety standards. This paper presents a numerical analysis of the magnetic field characteristics of compact unconventional HSIL transmission lines with different subconductor configurations. The results show that the proposed HSIL designs can reduce the magnetic field at ground level by up to 71.74% compared to a conventional 500 kV line near the center, as well as by up to 74% at the right-of-way edge, while maintaining magnetic field levels well below the limits set by ICNIRP and state-specific regulations. This study evaluates the magnetic field distribution within the right-of-way, providing insights into the electromagnetic performance and potential implications for transmission line design. 

Incorporating nonlinear resistive field grading materials (FGMs) onto metal-brazed substrates has been widely investigated as an efficient electric field reduction strategy at triple points (TPs) within ultrawide bandgap [(U)WBG] power modules. However, most investigations have been carried out using either dc or sinusoidal ac voltages despite actual (U)WBG power modules operating with high-frequency square voltages featuring high-slew rate ( dv/dt ). Thus, this study introduces a field-dependent conductivity (FDC) layer to analyze electric field reduction under high-frequency, high-slew-rate square voltages. Using COMSOL Multiphysics, both coated and uncoated structures were modeled to evaluate electric field reduction. When employing nonlinear FDC coating, the findings demonstrate a notable decrease in field stress, even under square voltages with rapid rise times and high frequencies. However, relying solely on the nonlinear FDC layer may not adequately address the electric field concerns, particularly when factoring in protrusions on metallization layers and reducing layer coverage. In response to this challenge, protrusions at the metal ends are incorporated into a protruding substrate configuration. This entire structure is then coated with a nonlinear FDC layer. The combined impact of the protruding substrate and nonlinear FDC layer effectively reduces the electric field. However, when the rise time is shortened to 75 ns and the frequency is raised to 500 kHz, the electric field stress around TPs exceeds the insulation’s withstand strength. This finding underscores the need for further research into alternative strategies as the prevalent strategies are unable to effectively mitigate electric fields in real-world operating conditions of (U)WBG power modules. 

Electric vehicles (EVs) rely on robust inverter-to-motor connections to ensure high-efficiency operation under the challenging conditions imposed by wide-bandgap (WBG) semiconductors. High switching frequencies and steep voltage rise times in WBG inverters lead to repetitive transient overvoltages, causing insulation degradation and premature motor winding failure. This study proposes a wideband (WB) model of EV cables, developed in EMTP-RV, to improve transient voltage prediction accuracy compared to the traditional constant parameter (CP) model. Using a commercially available EV-dedicated cable, the WB model incorporates frequency-dependent parasitic effects calculated through the vector fitting technique. The motor design is supported by COMSOL Multiphysics and MATLAB 2023 simulations, leveraging the multi-conductor transmission line (MCTL) model for validation. Using practical data from the Toyota Prius 2010 model, including cable length, motor specifications, and power ratings, transient overvoltages generated by high-frequency inverters are studied. The proposed model demonstrates improved alignment with real-world scenarios, providing valuable insights into optimizing insulation systems for EV applications.