To research the strain characteristic and its measurement method of encapsulation insulation for dry-type air-core reactor, the methods of making test model, embedding sensor and strain gauge, and calculating strain were studied. A test model was made and a test system was built, and the internal strain of encapsulation was studied during the process of reducing temperature and applying current at different low temperatures. The results show that the circumferential thermal expansion coefficient of the encapsulation insulation is less than the axial thermal expansion coefficient and there is anisotropy, which makes the circumferential strain larger than the axial strain. During the process of reducing temperature, negative strain is produced by circumferential shrinkage of the encapsulation insulation, which decreases gradually with the temperature decreasing, the decline rate gradually slows down in the same cabin temperature, and the value increases significantly with the increase of temperature decline amplitude in different cabin temperatures. The axial strain is positive when the cabin temperature is higher, which gradually changes to a negative value with the temperature decreasing, and the change law also changes from gradually increasing to gradually decreasing with the temperature decreasing. During the process of reducing temperature, the circumferential and axial strains have negative jumps many times, resulting in shrinkage micro-cracks. The strain change during process of applying current is contrast to the process of reducing temperature, with the increase of temperature, the circumferential strain increases gradually, the axial strain decreases rapidly, and neither strain jumps. By calculating the maximum thermal stress, it is further verified that the circumferential compression stress is larger than the compression strength of the epoxy glass fiber, resulting in the damage of encapsulated insulation.

Current-carrying capacity is an important indicator of cable transmission capacity, which directly affects the operation reliability and economy of HVDC cables. According to the electric field distribution characteristics in the insulation layer of DC cable, an analytical calculation method of the electric field distribution inside and outside the insulation layer based on the equivalent conductivity was proposed. Taking a ±535 kV XLPE insulated DC cable as example, considering the highest operating temperature of cable conductor and the maximum allowable temperature difference of insulation layer, we obtained the load control domains of the HVDC cable under different operating conditions. The results show that the current-carrying capacity and application characteristics of HVDC cables can be analyzed by the electric thermal field decoupling method effectively, and the maximum temperature difference of insulation layer is the core factor limiting the current-carrying capacity of DC cable below critical ambient temperature. Under the critical ambient temperature, raising the highest operating temperature of conductor has limited influence on the current-carrying capacity, while optimizing the electrical resistance of insulating materials and cable structure is the key to improving the current-carrying capacity.

On the basis of laser ultrasonic technology, a peak reconstruction algorithm of surface wave was studied, and an experimental platform of two-dimensional laser excitation scanning laser ultrasonic detection for basin insulators was built. Then the artificial bubble, impurity, and crack defects were detected and studied, and the basin insulator with crack fault in practical field application was carried out off-line detection. The results show that the reconstructed peak image based on laser ultrasonic peak reconstruction algorithm can better reflect the defect information of basin insulator in scanning interval, which proves that this method can realize the off-line detection of surface crack defect on the basin insulator.

Firstly, a corresponding simulation model was built on the basis of terminal structure of 220 kV high-voltage dry cable, and combined with the nonlinear conductivity equation of insulating materials, the electric field distribution and temperature distribution in the terminal with different reinforced insulating materials, ambient temperature, and applied voltage were studied. And then, the electric field distributions of the terminal with defects such as misplacement of stress cone installation, surface bulge, and bubbles in the reinforced insulation were compared and analyzed. Finally, the corner shape of stress cone and the distance between stress cone edge and reinforced insulation were optimized, the electric field distribution of the terminal after optimization was analyzed, and the optimal distance between stress cone edge and reinforced insulation was proposed. The results show that the nonlinear silicone rubber insulating material can well homogenize the electric field. The change of external ambient temperature will decrease the temperature difference between the internal core and the external umbrella skirt, and the maximum field strength in terminal increases significantly with the increase of ambient temperature. The stress cone installation dislocation makes the field strength at the three-phase junction increase sharply. The bulge on stress cone surface makes the local field strength in terminal increase sharply. When there are bubbles in reinforced insulation, the bubble size has little effect on the maximum field strength in the cable terminal. By changing the corner shape of stress cone into a circular arc shape, the field strength at the corner decreases by 75.26%. By increasing the distance between stress cone edge and reinforced insulation to 5 mm appropriately, the field strength at the stress cone corner decreases.

Basin insulator is an important part of gas insulated closed combination switchgear (GIS) device, and its quality has an important impact on the construction and operation of power grid. In this paper, the failure causes of basin insulators were described, and the existing detection methods were compared in common cracking locations. According to the material characteristics of basin-type insulators and field test conditions, the probe frequency, K value, and chip size were calculated theoretically. An ultrasonic water immersion focusing oblique probe device was developed, a method of detecting cracks near the bolt holes of basin insulator by using the low-frequency dual-probe ultrasonic detection technology was proposed, and the test results were verified by laboratory penetration and ray detection. The results show that the ultrasonic refraction transverse wave with high signal-noise ratio can be generated in the basin insulator by using dual probes with 2 MHz 18×18 mm of model size and 24.8°-35.4° of angle (α_L) between the axis of the wafer emission acoustic beam and the normal line of workpiece interface. It is feasible to use special low frequency double probe ultrasonic detection technology to detect the defects of GIS basin insulators.

A novel film capacitor was prepared by using a mass-produced surface modified high dielectric polypropylene film, and the power density, energy storage properties, capacity retention ratio, and the cycle life under large current of the capacitors were studied. The results show that the maximum energy storage density of the new capacitors with the surface modification polypropylene film can reach to 3.2 J/cm³, and the capacitor shows excellent comprehensive performances.

Three kinds of soluble polyimide (PI) resins were prepared from 4,4′-hexafluoroisopropylidene)bisphthalic anhydride (6FDA) and three kinds of romatic diamine monomer containing rigid-rod amide bonds in the molecular chains by one-step high temperature solution polycondensation reaction, respectively. And then three kinds of transparent PI films were prepared by the N,N-dimethylacetamide (DMAc) solution of the above resins. The films were tested by attenuated total reflection Fourier transform infrared spectroscopy, thermogravimetric analysis, dynamic mechanical analysis, thermomechanical analysis, and UV-visible spectrum, and their yellowness index was tested. The results show that the PI films exhibit good optical transparency, their ultraviolet cutoff wavelength is below 380 nm and the optical transmittance is over 80% at the wavelength of 500 nm. In addition, the PI films exhibit good thermal stability with the glass transition temperatures (T_g) higher than 320℃ and the 5% weight loss temperatures (T_5%) over 520℃. The linear thermal expansion coefficients (CTE) of the PI films are all lower than 50×10^-6/K, indicating that the introducing of rigid amide bonds can efficiently enhance the high-temperature dimensional stability of the solution-processable fluoro-containing PI films.

The effect of different contents of bis-triethoxysilylpropyl tetrasulfide (Si69) and bis(tert-butylperoxy diisopropyl) benzene (BIBP) on vulcanization characteristics, mechanical properties, and electrical insulation property of EPDM were compared and analyzed. The results show that with the increase of Si69 and BIBP content, the curing speed increases, the process positive curing time decreases, the maximum torque increases, the crosslinking density of the rubber increases and the mechanical properties are improved. With the increase of Si69 content, the electrical insulation property of the rubber decreases; with the increase of BIBP content, the electrical insulation property of the rubber increases gradually.

In this paper, three metal-organic framework (MOF) materials MOF-505, Cu-BTC, and MIL-100(Fe) were prepared by solvothermal method, and Cu-BTC with the highest adsorption capacity was selected. The equilibrium adsorption capacity of Cu-BTC, activated carbon, 13X molecular sieve, and activated clay at different initial concentrations and adsorption temperatures was systematically studied. The difference among the adsorption characteristics for aminophenazone of the MOFs was explained by simulation calculations using simulation software. The results show that the adsorption capacity for aminophenazone of Cu-BTC is much higher than that of the other three adsorbents. Under different temperature, the equilibrium adsorption capacity of BTC for aminophenazone at different initial concentrations has much difference, thus the appropriate adsorption temperature should be selected to achieve the optimal adsorption capacity.

Crosslinked polyethylene/organic montmorillonite (XLPE/OMMT) nanocomposites were prepared by melting blending method. The performance of samples before and after thermal ageing were characterized by small angle X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), and mechanical properties test. The results show that with the mass fraction of 0.5%, OMMT can be well dispersed in the matrix before ageing. However, OMMT agglomerates when the filler doping amount increases. There are only a few chemical bonds between OMMT and XLPE matrix, they mainly coexist in the form of physical entanglement. The crystallinity of nanocomposites decreases due to the space steric effect of OMMT lamella. After ageing, the layer spacing of XLPE/OMMT-0.5% samples decreases and the crystallinity increases. With the increase of OMMT doping amount, the interlayer spacing of OMMT increases due to the breakdown of XLPE molecular chain and the thermal rearrangement of OMMT in matrix. Due to thermal ageing, the completeness of crystal structure of nanocomposites gets worse, the crystal size distribution becomes wider, and the crystallinity decreases significantly. The molecular chain structure of nanocomposites is seriously damaged by thermal oxidation and thermal cracking. The mechanical property of XLPE/OMMT-0.5% decreases slightly after ageing, and when the content of OMMT exceeds 0.5%, the mechanical properties of nanocomposites decrease seriously. And the samples become brittle and hard.