In this study, the active noise control (ANC) method was used to suppress high-decibel and low-frequency power transformer noise. An appropriate ANC system was selected based on the transformer noise characteristics and experimental condition. A new filter-X least mean square (FXLMS) adaptive ANC algorithm based on offline and online secondary-path modeling was proposed to realize faster and more stable secondary-path online modeling than that of the random white-noise FXLMS algorithm and to ensure the convergence, stability, and reduction in transformer noise control. Moreover, the genetic algorithm is adopted to optimize the convergence coefficient, while the effect of the convergence coefficient on the algorithm was analyzed using simulation and theory. In addition, the transformer noise online monitoring and active control system was designed including software and hardware, and the hardware devices were selected based on the noise feature. In the 50 000 KVA transformer noise reduction experiment, the system achieved a noise reduction of 8-15 dB and an 84.10-96.86% decrease in average sound energy density in a certain area.

The surface charge accumulation is very likely to trigger the surface flashover, which limits the large-scale application of DC GIL/GIS. This article comprehensively reviews the effect of six factors, including insulator-electrode shape, surface roughness of the insulator and conductor, metal particles, temperature, humidity, and gas type, on the insulator surface charging property. Furthermore, three models i.e. ‘analogous ineffective region’ expansion model, charge cluster triggered surface flashover model, and synergistic model of adsorbed gas, revealing the mechanism of charge triggered surface flashover phenomenon are reviewed and discussed. Future work from the perspective of theoretical analysis and engineering application are suggested in this field.

The winding is the core component of a transformer, and the technology used to diagnose its current state directly affects the operation and maintenance of the transformer. The mechanical vibration characteristics of a dry-type transformer winding are studied in this paper. A short-circuit test was performed on an SCB10-1000/10 dry-type transformer, and the vibration signal at the surface was measured. Based on actual experimental conditions, a vibration-simulation model of the transformer was established using COMSOL Multiphysics software. A multiphysics coupling simulation of the circuit, magnetic field, and solid mechanics of the transformer was performed on this model. The simulation results were compared with measured data to verify the validity of the simulation model. The simulation model for a transformer operating under normal conditions was then used to develop simulation models of transformer-winding looseness, winding deformation, and winding-insulation failure, and the winding fault vibration characteristics were analyzed. The results provide a basis for detecting and analyzing the mechanical state of transformer windings.

Atmospheric non-equilibrium plasma sterilization technology has been applied in the food processing, medical and health fields because of advantages such as short application time, low-temperature operation, high efficiency and safety. Research has shown that the active particles in the plasma play a decisive role in sterilization. However, the micromechanisms underlying the interaction between the active particles and biological components remain unclear. In this paper, with the common deteriorative microorganism Saccharomycodes as the research object, we examined the interaction between reactive oxygen species (O, OH, HO ₂ and H ₂ O ₂ ) and glucan in the cell wall using a reactive force field molecular dynamics (ReaxFF MD) simulation methodology. We found that these reactive oxygen species reacted with the glucan structure by hydrogen abstraction reactions to cleave chemical bonds (C–O and C–C), resulting in cell wall destruction. Of these species, the O and OH species attract H atoms from the structure; these atoms are highly active and can easily break C–C bonds and release monosaccharides from the branched glucan chains. The H atoms in HO ₂ and H ₂ O ₂ are strongly attracted to the glucan structure. Next, the C–O bonds are easily broken, leading to destruction of the chain structure, mainly because of the cleavage of the glucoside bonds. This simulation study adds to the understanding of the micromechanism of the ROS-mediated destruction of the cell wall glucan of Saccharomyces cerevisiae and of plasma sterilization at the atomic level.