Search

The regeneration of transformer oil is a trending topic in the dielectric research field. However, the normal way of regeneration requires high cost and complicate process. In this paper, the non-woven polypropylene (PP) electret films were modified by fluorination and corona method to achieve the regeneration function for transformer oil. The results show that the C-H bonds in polypropylene were replaced by C-F bonds during the fluorination process, resulting in the mean diameter of the fibers being decreased to a value of 1.7 μm. The increased roughness of the fibers leads to super hydrophobicity. Further research revealed that the insulation properties of aging oil recovered after filtration by corona charged fluorinated fiber membranes. The result is especially significant for breakdown voltage, the values of which reached half of the original insulating oil. In conclusion, the combination of fluorinating and corona charging method on PP fiber membrane shows great potential for insulation oil regeneration.

The grounding body of the transmission tower is of great significance to the safe operation of the power system, its corrosion state needs to be accurately detected to ensure a safe discharge channel for lightning current. In this paper, transient electromagnetic method is employed to detect the corrosion of tower grounding body. Based on the distribution characteristics of magnetic induction intensity, the location of grounding conductor with corrosion or breakpoint can be accurately located. The model of tower grounding body is established by COMSOL multiphasic software, and the influence of different corrosion degree, conductor material and soil resistivity on magnetic induction intensity is analyzed in detail. Field experiments are carried out to verify the effectiveness of the method.

For current photovoltaic devices, the portability is poor, the intelligence of device is low, and the stability of the system and the power conversion efficiency are not high. This design uses the photovoltaic panel as the input. By setting up the battery mathematical model and simulation, the maximum power MPPT is tracked to extend the service life of the photovoltaic cell system. The constant current charging and constant voltage discharge of the battery should be as high as possible to achieve efficient conversion control. The output of the battery is boosted to a stable value through the BOOST circuit, and the DC-DC and DC-AC systems are built separately. DC-DC and DC-AC perform linear regression using the SVM training parameters for the voltage and set values of the BUCK circuit and the inverter. By adjusting the fitting parameters offline, the PWM and SPWM of the BUCK circuit and the inverter circuit are respectively adjusted to meet the use of low-power AC-DC devices. The design of the control section is based on the MSP430F149. When the CPU is idle, it enters a low-power mode to meet the low-power requirements of the PV system. The device realizes the portability of the photovoltaic system and the intelligent voltage output, and the system has a stable conversion efficiency.

This paper aims to study the feasibility of improving pulsed current output by using High temperature superconducting (HTS) air-core transformer. Based on the theoretical analysis, the simulations are done. Results of the simulations indicate that the HTS air-core pulse transformer can magnify the output current magnitude and accelerate the velocity of discharge. However, when a series of inductor modules use the same one HTS air-core transformer, the residual current may influence the discharging waveform. To eliminate residual current, self-coupling discharging model is proposed. The simulated and experimental results illustrate that a self-coupling model can eliminate the residual current effectively. The results of this analysis contribute to the research of superconducting inductor pulsed current output.

For the magnet used in power apparatus, the inductance is an important parameter which may change the input-output characteristic of the apparatus. In research of the high temperature superconducting (HTS) magnet in energy storage system and other electric apparatus, we found the difference of the magnet's inductance between normal state and superconducting state. In this paper, the electromagnetic models of Bi2223/Ag tape and windings are established firstly. Based on the simulation analysis and measured results, the reason of inductance variation of HTS magnet has been clarified. The regularity of inductance variation of HTS pancake and magnet has been researched, and new requirement for the veracity in the process of superconducting magnet's design has been claimed.