A polyacrylonitrile (PAN)/styrene-isoprene-styrene (SIS) composite fiber membrane was prepared by electrospinning method. The effects of different PAN/SIS ratios on its porosity, liquid absorption, thermal stability, mechanical properties were studied. The results show that when the ratio of PAN to SIS is 8∶2, the SIS/PAN composite membrane fiber prepared has the most cross-linked structures, uniform size, and the best mechanical properties. The tensile strength is 20.29 MPa, the porosity and absorption rate reach 47.8% and 310.7%, respectively, and the ionic conductivity is 2.03×10^-4 mS/cm. Under the condition of 0.2 C multiplier, the initial discharge specific capacity of Li-ion battery assembled by the composite fiber membrane is 146.4 mAh/g, the discharge specific capacity fluctuates little after 50 cycles, and the capacity retention rate is as high as 98.02%, showing good cycle stability.

The discharge characteristics of column-plate electrode structure under high frequency excitation were studied by combining experiment and simulation under different solution concentrations. The discharge characteristics of gas-liquid two-phase dielectric barrier discharge (DBD) were measured through experiment, and the electrical and luminescent characteristics under different solution concentrations and applied voltage amplitudes were obtained. On this basis, the equivalent circuit model corresponding to this experiment was established by combining with the physical process of gas-liquid two-phase discharge. The model parameters were determined by combining the experiment with the electric field simulation, and the circuit simulation model was established in Simulink. The voltage and current waveform, and Lissajous graph under different concentration and voltage amplitude were obtained through simulation. The correctness of the simulation model was verified by comparing simulation and experimental results. The discharge parameters, such as air gap voltage, liquid phase voltage, discharge channel current, and energy ratio, which could not be obtained in the experiment directly, were further extracted by the above model. The results show that the solution concentration has no significant influence on the voltage and current waveform and luminescence characteristics of the loop obtained by experiment. However, it is found through simulation that the proportion of energy consumed by gas phase and liquid phase are affected by it greatly. With the increase of solution concentration, although both liquid power and gas power increase, the liquid power increases faster, resulting in that the energy ratio of liquid phase increases obviously. The energy ratio of gas phase can be improved by increasing the excitation source voltage, which can inhibit the energy obtained by liquid phase to a certain extent.

PI nano composite films were conducted long-term multiple ageing at 270℃, 70℃ and 90%RH, and 320℃, and their thickness, dielectric spectra, conductivity, partial discharge initiation voltage, and insulation life at different ageing stages were tested. The results show that the insulating properties of the PI film has no obvious change after ageing at 270℃. The high humidity environment has a significant impact on the dielectric spectra, conductivity, and partial discharge initiation voltage of the PI film, but it does not shorten its insulation life. The internal structure of PI film would change under the high temperature of 320℃, which will shorten its insulation life by about 30%.

In this paper, the effect of DC-temperature composite field on the electrical tree growth characteristics was introduced. The effect mechanism of charge transport on the electrical tree deterioration under temperature and electric field coupling conditions and the research progress in electrical properties of epoxy nanocomposite dielectrics were reviewed.

The epoxy resin samples for dry type insulation equipment were conducted ageing test. The electric strength and dielectric spectrum of the samples with different ageing degree were tested, and their activation energy were calculated. It is found that with the increase of ageing degree, the activation energy of the epoxy resin shows a change trend of decreasing-increasing-slightly decreasing-increasing, and the electric strength shows a zigzag downward trend. The accelerated ageing time at high temperature can be converted into operating time at working temperature by the accelerated ageing factor (AF) obtained by Arrhenius equation. Taking that the electric strength decreases to 50% of the initial value as a sign of life end for material, we could obtain the activation energy corresponding to the life end of epoxy resin material, which is 209.7 kJ/mol. The judging method of the insulation state and life for epoxy resin dry type insulation based on activation energy is established, and the connection mode and test method of dielectric spectrum measurement for dry type insulation equipment are proposed by taking dry type transformer as an example. The life prediction method is applied to an actual dry type transformer in the project, it is obtained that the activation energy of the dry-type transformer is 69.4 kJ/mol, and the its minimum residual life is predicted to be 36.5 years.

Combining with the relationships among the DC submarine selection, voltage level, and transmission capacity of HVDC submarine cable projects in China, taking the raw material input of DC submarine cable required per unit transmission capacity as a typical economic index, we find that with the increase of voltage level and current capacity of the single loop DC submarine cable, the economy of DC submarine cable increases. By comparing the materials consumable variation of different routes after improving the voltage level and transmission capacity, we find that it is more effective to improve the economy of DC submarine cable by increasing the electrical level of DC submarine cable insulation and the maximum operating temperature of conductor to improve the voltage level and transmission capacity, respectively. In addition, a ±525 kV DC submarine cable with the highest conductor operating temperature of 70℃ was selected as the typical specification, and its insulation field strength distribution variations were analyzed through finite element simulation when the applied voltage and conductor operating temperature increased to 972 kV and 90℃, respectively. The results show that the increase of voltage level and conductor operating temperature will both cause a further increase of field strength close to insulation shield after the insulation field strength reversal, and there is a synergism effect between them. On this basis, a semicircular protuberance with 0.125 mm of depth was set on the interface of insulation shield into insulation, and the finite element simulation results show that the field strength at the protuberance increased by 35.4% compared with the case without protuberance.

Aiming at the lack of metal passivator in oil for 22 transformers in a power grid company, a self-developed metal passivator adding device was used to add metal passivator, and the adding effect of metal passivator was verified by sampling and detecting the metal passivator content and corrosive sulfur regularly. The results show that adding metal passivator can alleviate the corrosion of corrosive sulfur to transformer effectively, and the key problems during the adding process of metal passivator are pointed out, which are preventing oil leakage, preventing air mixing in, controlling injection flow, and preventing pollutants mixing in.

A series of accelerated thermal ageing tests were conducted on some nuclear cables. On the basis of Arrhenius model, the apparent activation energy of nuclear cable materials was obtained using the elongation at break method and the dielectric loss spectrum method, and the effect of activation energy variation on the ageing life evaluation of nuclear cable materials was studied. Then the thermal ageing reference curves of nuclear cable materials were developed on the basis of fixed activation energy and varying activation energy, respectively, and verified by experiments. The results show that the apparent activation energy decreases gradually with the ageing of cable materials. A small change of apparent activation energy will have great impact on the life evaluation of cable materials. The thermal ageing reference curve on the basis of varying activation energy is more consistent with the actual ageing trend of cable materials, which can be used for the ageing life evaluation of nuclear cable materials.

DGEBA/OSC cross-linked epoxy resin blend systems with different proportions were constructed by molecular dynamics (MD) simulation using methyl tetrahydrophthalic anhydride (MTHPA) as curing agent, and the blend system samples were prepared. The thermodynamic properties of the blending systems were studied by simulation and experiment. The simulation and test results show that with the increase of the OSC proportion, the glass transition temperature (T_g) of the blend systems increases, when the molar ratio of DGEBA to OSC is 6∶4, the T_g increases by 30.7 K. The elastic modulus and strength of the systems increase at first and then decrease, and reach the optimum at 8∶2 of molar ratio. The addition of OSC can reduce the fractional free volume (FFV) and mean square displacement (MSD) of the systems, and weak the molecular segment movement ability. The calculation results of synergy rotational energy barrier and cohesive energy density (CED) show that the blend system with stronger molecular segment rigidity and larger interaction force between segments has better thermodynamic properties.

In order to deeply grasp the breakdown characteristics of AC 500 kV cross-linked polyethylene (XLPE) submarine cable insulation materials under electrical-thermal stress and establish an electrical-thermal combined lifetime model, we conducted electrical-thermal breakdown experiments on the XLPE material at 25, 40, 55, 70℃ under step stress firstly. The AC electric strength and voltage duration time were analyzed by Weibull distribution to obtain the equivalent AC electric strength and voltage duration time at different temperatures. Then the FALLOU, SIMONI, CRINE models were established by multiple linear regression method, and their error was analyzed. Finally, an E-T lifetime model for the AC 500 kV XLPE material was constructed. The results show that at the same temperature, the equivalent electric strength decreases with the increase of voltage duration time of each voltage stage. At the same voltage duration time of each stage, with the increase of temperature, the equivalent AC electric strength and voltage duration time both firstly increase and then decrease. The analysis on the electrical-thermal lifetime models indicate that the fitting error of FALLOU, SIMONI, CRINE models is large, and their fitting goodness do not meet the accuracy requirements. An improved electric-thermal combined ageing lifetime model is obtained by using stepwise regression to calculate the significance and correlation between electric-thermal variables and lifetime, and the error analysis show that it has better fitting accuracy.