High Voltage最新文献

Interface design for synergistic improvement of the thermal conductivity and dielectric properties of dielectrics is urgently needed but still challenging for the next generation of electronic and electrical equipment development. Herein, the authors report a strategy to screen structural units for the interface design of polymer dielectrics working under high-frequency and high-voltage conditions. Thermal conductivity, dielectric loss, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) gap are employed as key parameters to be considered simultaneously in the interface design for the screening. The authors find that a rigid ring with hydroxyl groups at symmetric sites can suppress the steric hindrance of neighbouring hydrogen bonds, leading to a better phonon spectrum matching and more efficient suppression of molecular chain segment motion, which ensures the dielectric insulating performance and thermal conduction performance simultaneously. Typically, alkyl polyglucoside (APG) was selected as the optimal modifier to demonstrate the interface designing principle experimentally, exhibiting improved thermal conductivity and suppressed dielectric loss, ultimately resulting in a 4.98-fold increase in the high-frequency breakdown time. This study provides important insights into decisive structural factors necessary to achieve dielectrics with excellent insulating properties under high-frequency applications.

The thermal effect and hydrodynamic perturbation within a high-frequency pulse-periodic nanosecond coplanar surface dielectric barrier discharge (ncSDBD), are studied experimentally and numerically. The discharge is initiated in a coplanar open electrodes arrangement with 10 mm inter-electrode gap for pulse repetition frequencies (PRF) between 10 and 100 kHz. The discharge morphology, heat release, ozone distribution and refractive index perturbation with different repetition frequency are measured by intensified charge-coupled device (ICCD) imaging, spatially resolved emission spectroscopy, optical absorption methods and the background-oriented schlieren technique, respectively. With the increase of frequency and number of pulses, the discharge morphology changes from quasi-uniform structure at 10 kHz to filamentary mode, and a higher gas temperature is observed near the grounded electrode. In turn, the gas heating largely determines the dynamics of ozone. The discharge characteristics and hydrodynamic perturbation are modelled and analysed numerically. The existence of the exposed grounded electrode facilitates the connection between the positive and negative discharges. During the afterglow phase, a large amount of positive charge accumulates near the two exposed electrodes due to charge separation, resulting in a strong body force, which triggers the blowing up of the flow.

Improving the computational efficiency of multi-physics simulation and constructing a real-time online simulation method is an important way to realise the virtual–real fusion of entities and data of power equipment with digital twin. In this paper, a data-driven fast calculation method for the temperature field of resin impregnated paper (RIP) bushing used in converter transformer valve-side is proposed, which combines the data dimensionality reduction technology and the surrogate model. After applying the finite element algorithm to obtain the temperature field distribution of RIP bushing under different operation conditions as the input dataset, the proper orthogonal decomposition (POD) algorithm is adopted to reduce the order and obtain the low-dimensional projection of the temperature data. On this basis, the surrogate model is used to construct the mapping relationship between the sensor monitoring data and the low-dimensional projection, so that it can achieve the fast calculation and reconstruction of temperature field distribution. The results show that this method can effectively and quickly calculate the overall temperature field distribution of the RIP bushing. The maximum relative error and the average relative error are less than 4.5% and 0.25%, respectively. The calculation speed is at the millisecond level, meeting the needs of digitalisation of power equipment.