An efficient method is proposed for predicting the attenuation and distortion of the damped oscillation surges traveling on single-phase overhead lines under the influence of corona and frequency dependence of line parameters. The Finite Difference Time Domain (FDTD) algorithm is employed in the transient computation. The Suliciu's corona model is extended to simulate the charge-voltage curves with minor loops under the damped oscillation surges. The corona effect is considered by adding a corona current term in the telegraphers' equations. The frequency dependence effect is also taken into account by using the vector fitting and recursive convolution in time domain. The computed voltage waveforms are compared with the measured ones to examine the validity of the proposed method. The computed results show that the minor loops have a greater effect on the attenuation and distortion for the damped oscillation surges under negative polarity.

An exploration on the grounding characteristic of monopile foundation offshore wind turbines (WTs) is carried out in this paper by using the Grounding System Safe Analysis Software (GSSAS). A basic description is given for the structural feature of the monopile foundation. The discretization model is built for the monopile foundation by subdividing its continuous shell body into a discrete multiconductor system. The simulation computation is performed for analyzing the actual factors influencing the grounding resistance, including the seawater depth, thickness of clay layer, and resistivity of gravel layer. It is found from the simulation computation that the grounding resistance is mainly influenced by the seawater depth. Then, the result obtained from the software GSSAS is also compared with that from the software current distribution, electromagnetic fields, grounding and soil structure analysis for checking the validity of the GSSAS simulation in the exploration of grounding characteristic of offshore WTs.

In the high‐humidity environment, the epoxy resin (EP) insulating materials commonly used in reactors and other equipment are prone to accelerate ageing due to the damp and hot conditions, which affects the long‐term stable operation of the equipment. However, at present, the research on the blocking effect of carbon nano‐modified fillers on the invasion of water molecules into the epoxy resin matrix is still unclear. Based on this, we utilised molecular dynamics simulation technology to establish six EP models of EP materials under different conditions, including water molecule invasion (WI)/non‐invasion (WNI) and carbon nanomaterial modification/no modification. The carbon nano‐modified materials adopted Amido‐Amine Functionalised Carbon Nanotube (AFCNT) and Hydroxyl Functionalised Graphene (HFGNP). We studied the changes in key performance indicators such as relative permittivity, thermal conductivity, and glass transition temperature of six models. Eventually, it was found that the relative permittivity of the EP model significantly increased after water molecule invasion but decreased after doping with AFCNT. The thermal conductivity of the six EP models increased, and the increase in the AFCNT‐EP model was the most obvious, rising by 46.65% at 300 K. The glass transition temperatures of the models all decreased, but the decrease was reduced after doping and modification with carbon nanomaterials. Overall, except for thermal conductivity, the overall performance of the EP model deteriorated to varying degrees after water molecule invasion. However, the performance deterioration trend of the model was alleviated after doping with carbon nano‐modified fillers, and the performance of the model doped with AFCNT was significantly better than that of the EP model doped with HFGNP. This research can provide certain theoretical basis and technical support for the engineering application of epoxy resin materials under extreme conditions such as high humidity.

Interfacial stress concentration induced by curing shrinkage during the manufacturing of epoxy resin is a primary trigger for micro-nano defect formation and electrical performance degradation in power equipment. To address the computational complexity of traditional viscoelastic models and the thermoelastic behavior wherein the stiffness of the epoxy resin varies with temperature during curing, this paper proposes an improved viscoelastic constitutive model incorporating a thermo-elastic factor. By coupling curing kinetics, heat conduction, chemical shrinkage, and mechanical effects, a multi-physics simulation framework is constructed to describe the complete epoxy curing process, thereby revealing the spatiotemporal evolution of curing stress deformation. To verify the model’s accuracy, an in situ monitoring system based on Fiber Bragg Grating (FBG) sensors was established. A temperature compensation method was utilized to effectively decouple temperature and stress within the complex exothermic curing environment. This study reveals a significant strain gradient effect during the resin curing process. Experimental measurements indicate strains of 21,609 με and 5800 με at the interface and surface, respectively, with numerical simulations exhibiting high agreement with the experimental data. This research not only provides an efficient simulation approach for predicting curing stress but also offers a theoretical basis for the crack-resistant structural design of high-performance epoxy-based power equipment.

With the development of the new energy industry in high-altitude regions, epoxy resin insulating materials in electrical equipment face severe challenges from prolonged exposure to strong radiation environments. Strong ultraviolet irradiation induces the generation of free radicals such as alkyl (CH₂), alkoxy (CH₂O), and peroxyl (CH₂OO), which continuously attack the cross-linking structure of epoxy resin, leading to its degradation. This study employs molecular dynamics simulations to evaluate the enhancing effect of graphene quantum dots (GQDs) on the radiation resistance of epoxy resin (EP), proposing cross-linking structural integrity as an evaluation criterion. It compares and analyses pure EP (EP/neat), hydrogen-terminated GQDs (EP/GQD_C₅₄H₁₈), and carboxyl-terminated GQDs (EP/GQD_COOH) under three types of free radicals. The results indicate that the unique sp² hybrid structure and hydrogen-donating ability of GQDs can effectively inhibit the activity of free radicals, and improve the integrity of the cross-linked structure by 8% to 16% compared to EP/neat. While both types of GQDs demonstrate comparable behavior in response to alkyl free radicals, EP/GQD_COOH exhibits superior performance under the influence of oxygen-containing free radicals. This enhanced performance can be attributed to its augmented hydrogen-donating capacity and an increased number of active sites. This study investigates the extent to which GQDs with different structures enhance the radiation resistance of epoxy resins, providing an important theoretical basis for the modification of epoxy resins for applications in high-radiation environments.