High Voltage最新文献

Fibre optic F-P sensor has become one of the mainstream detection methods for partial discharge faults due to their advantages of good insulation, high sensitivity, resistance to electromagnetic interference, simple structure and inexpensive pricing. The first-order resonant frequency of the acoustically sensitive diaphragm of the F-P sensor is given based on the theory of plate and shell vibration, and the fibre optic F-P sensing array is designed based on the Fabry–Perot interference principle. A sensor installation method is also proposed for introducing a fibre optic F-P probe into the power transformer interior using a fibre optic penetrator through flange at the power transformer oil change valve. A system of non-linear equations is developed by utilising the time difference of arrival (TDOA) of the partial discharge ultrasound signal propagation to the F-P sensing array. The Chan-WLS algorithm is used to convert the non-linear equations in the TDOA localisation method into a non-linear optimisation problem to be solved and experimentally verified on the 220 kV real power transformer. The experimental results show that the error in the partial discharge fault localisation is solved based on the Chan-WLS algorithm and the actual location is 20.27 cm, which is within the acceptable error.

To further study the thermal-oxidative ageing mechanism of crosslinked polyethylene (XLPE), the terahertz frequency domain dielectric parameters and relaxation phenomena of thermal-oxidative aged XLPE are analysed using terahertz time domain spectroscopy. It is found that the real part of the terahertz dielectric constant increases with the increase of thermal-oxidative ageing duration, and the imaginary part shows an overall upward trend. Relaxation of the complex dielectric constant of the aged XLPE samples is obvious. Through the second-order Cole–Cole equation fitting, it is found that there are two relaxation processes around 0.15 and 1.5 THz, and the relaxation strength gradually increases with the ageing time. To explain this phenomena, microstructure changes and crystallisation behaviours are characterised using Fourier transform infrared spectrum and differential scanning calorimetry, respectively. It is suggested that the two relaxations may be caused by elastic dipole polarisation originating from the angular deflection of polar groups and stretching rotation of hydrogen bond. In addition, by comparing the relaxation strength in different temperatures, the source of the relaxation process is further confirmed.

Effective monitoring and early warning of overhead power lines are critical for ensuring power supply stability and personnel safety. However, existing methods that rely solely on single vision or light detection and ranging (LiDAR) have limitations such as numerous invalid alarms, hardware equipment constraints, and lack of real-time monitoring capabilities. This article proposes an intelligent monitoring method for safety distance of the powerline corridor based on heterogeneous sensor information. Firstly, an optimised single-stage detector is designed to detect safety hazard objects. In the detector, the backbone network and the sample matching strategy are improved; in addition, the learning strategy is adjusted. Next, the pose transformation relationship is obtained through the visual matching of prior LiDAR information and images. The back projection transformation of 2D–3D is achieved according to the relationship. Finally, a monocular camera-based end-to-end distance measurement scheme is proposed by combining 2D object information with coordinate transformation relationships. The scheme is applied to the distance measurements from hazard objects to powerlines. The experimental results show that the optimisation method improves the detection accuracy and reduces the computational complexity of the model. Also, case experiments with continuous frame data verify the effectiveness of the safety distance monitoring scheme.

In the article, a new type boost high-voltage nanosecond pulse generator is proposed. The distributed inductance of the transmission line is utilised as the energy storage unit and cooperated with the variable impedance transmission line transformer to generate nanosecond pulses with extremely high-voltage gain. What’s more, the isolation effect caused by the transmission line time delay is applied to achieve modular stacking. The demand for charging power supply can be greatly reduced, and few switches are used. Finally, the topological principle is verified by experiments, and a prototype of the five-stage stacking prototype is built. With the charging voltage of 28 V, the generator can output pulse with a voltage amplitude of 10 kV and pulse width of 12 ns whose voltage gain is up to 357 times.

Tree-contact single-phase-to-ground faults (TSFs) present a significant fire hazard in electrical distribution systems, and research on the development, modelling, and monitoring is insufficient. This article investigates the electro-thermal coupling mechanisms during the current rise of TSFs, constructing a simplified power–frequency model that leverages actual physical parameters like tree size for prolonged simulations of the first TSF stage zero-sequence current. Validated through full-scale testing, the model enables digital simulations across various tree sizes, concluding that the detection sensitivity for grounding faults should not exceed 0.5 A to mitigate fire risks effectively. This approach surpasses the limitations of traditional high-impedance fault models reliant on empirical parameters and the shortcomings of generalised conclusions from experimental inductions, offering a new paradigm for TSF research that enhances the predictive accuracy and applicability of fault analysis in electrical distribution networks.