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To study the surface flashover characteristics of single-phase basin-type insulators in gas insulated metal-enclosed switchgear （GIS） under low-frequency transmission， an electro-thermal-fluid coupling simulation is employed. Considering the temperature rise due to the skin effect and the temperature-dependent properties of material parameters， this approach calculates the electromagnetic loss， temperature rise characteristics， and surface electric field distribution of the basin-type insulator at different operating frequencies. Based on the time volume theory， the paper comprehensively considers the impact of temperature on the electric field distribution at the gas-solid interface and the generation rate of effective carrier to determine the surface flashover probability of the basin-type insulator at various voltage amplitudes and frequencies. The simulation results indicate that low-frequency transmission can effectively mitigate electromagnetic losses and reduce the maximum temperature inside the GIS enclosure. Furthermore， it offers higher surface flashover voltage for the same insulation configuration. This study provides theoretical support for verifying the insulation levels of gas-insulated high-voltage electrical equipment at different operating frequencies.

The high penetration of renewable energy sources (RESs) and power electronics devices has led to a continuous decline in power system stability. Due to the instability of grid-following converters (GFLCs) in weak grids, the grid-forming converters (GFMCs) have gained widespread attention featuring their flexible frequency and voltage regulation capabilities, as well as the satisfactory grid-supporting services, such as inertia and damping, et al. Notably, the risk of wideband oscillations in modern power grids is increasingly exacerbated by the reduced number of synchronous generators (SGs). Thus, the wideband oscillation suppression method based on adaptive active power droop control of GFMCs is presented in this paper. First, the stability of the hybrid grid-forming and grid-following system is obtained according to the improved short circuit ratio (ISCR), where the GFMC is in parallel at the point of common coupling (PCC) of the GFLC. Then, an adaptive adjustment strategy of the active power droop control is proposed to enhance the oscillation suppression capability across the full frequency range, thereby mitigating the wideband oscillation caused by phase-locked loop (PLL) synchronization in the GFLCs. Additionally, a first-order inertia control unit is added to the active and reactive power droop controllers to mitigate frequency and voltage variations as well as suppress potential mid-to-high frequency resonance. Finally, the wideband oscillation suppression strategy is validated by the simulation and experimental results. [ABSTRACT FROM AUTHOR]