The performance of polypropylene film determines the reliability of capacitors.This paper studies the change of insulation characteristics of the insulation dielectric polypropylene of high-voltage capacitors during t...The performance of polypropylene film determines the reliability of capacitors.This paper studies the change of insulation characteristics of the insulation dielectric polypropylene of high-voltage capacitors during the long-term operation process.Moreover,the correction of the insulation failure model of polypropylene media is implemented.Some conclusions are drawn from a series of experiments.The breakdown strength of the insulation dielectrics decreases as the withstand time rises,with amaximum decrease of 37.91%compared to the polypropylene sample without withstand voltage.As the electric field increases from−20 to−100 kV/mm,the total amount of space charge,the trap energy level and the trap density inside the polypropylene increase by 524.15%,18.99%and 773.36%,respectively.In the capacitor simulation model,the electric field in the capacitor increases by 19.62%after presetting space charge relative to the nonspace charge.The experimental data are substituted into the inverse power model,and the trap parameters are used to modify the model.The results show that the ageing state of the polypropylene has a negative exponential relationship with the trap parameters.This paper provides an important reference for the study of the failure mechanism of polypropylene in high-voltage capacitors and the assessment of polypropylene ageing state.展开更多
Surface discharge is a typical fault type in electric power equipment.High temperature in long-term operation can easily lead to ageing of materials,resulting in changes in surface characteristics and surface discharg...Surface discharge is a typical fault type in electric power equipment.High temperature in long-term operation can easily lead to ageing of materials,resulting in changes in surface characteristics and surface discharge faults.In this paper,a method of surface discharge identification of silicon rubber(SiR)based on spectral detection technology is presented.The surface discharge spectral characteristics of SiR with different ageing degrees are investigated,and the changes of microphysical and chemical properties and surface insulation properties caused by thermal ageing are analysed.The dynamic evolution of charge during surface discharge is simulated.The experimental results show that the spectral intensity of the surface discharge of the SiR material is mainly concentrated at 350,600 and 750-900 nm bands.The spectral intensity reaches the maximum value when the ageing time is 168 h.With the intensification of ageing,no new characteristic peaks generate in the discharge spectrum,but the proportion of the same characteristic peaks to the overall wavelength is different.The type of discharge material and ageing state are determined by the characteristic light intensity ratio Ib.The evolutionary mechanism of the discharge spectrum is revealed by the variation of flashover voltage,trap charge density,resistivity and other parameters.The simulation results show that the increase of electron density will lead to more intense electron collision,which will release more photons,resulting in enhanced spectral intensity.This work can provide a reference for the detection of surface discharge and the evaluation of ageing state of the equipment inside the high voltage box.展开更多
基金supported in part by the National Natural Science Foundation of China(Grant 52277153).
文摘The performance of polypropylene film determines the reliability of capacitors.This paper studies the change of insulation characteristics of the insulation dielectric polypropylene of high-voltage capacitors during the long-term operation process.Moreover,the correction of the insulation failure model of polypropylene media is implemented.Some conclusions are drawn from a series of experiments.The breakdown strength of the insulation dielectrics decreases as the withstand time rises,with amaximum decrease of 37.91%compared to the polypropylene sample without withstand voltage.As the electric field increases from−20 to−100 kV/mm,the total amount of space charge,the trap energy level and the trap density inside the polypropylene increase by 524.15%,18.99%and 773.36%,respectively.In the capacitor simulation model,the electric field in the capacitor increases by 19.62%after presetting space charge relative to the nonspace charge.The experimental data are substituted into the inverse power model,and the trap parameters are used to modify the model.The results show that the ageing state of the polypropylene has a negative exponential relationship with the trap parameters.This paper provides an important reference for the study of the failure mechanism of polypropylene in high-voltage capacitors and the assessment of polypropylene ageing state.
基金supported in part by the National Natural Science Foundation of China(Grant 52277153)in part by the Shandong Province Universities Youth Innovation Technology Support Plan(Grant 2021KJ023).
文摘Surface discharge is a typical fault type in electric power equipment.High temperature in long-term operation can easily lead to ageing of materials,resulting in changes in surface characteristics and surface discharge faults.In this paper,a method of surface discharge identification of silicon rubber(SiR)based on spectral detection technology is presented.The surface discharge spectral characteristics of SiR with different ageing degrees are investigated,and the changes of microphysical and chemical properties and surface insulation properties caused by thermal ageing are analysed.The dynamic evolution of charge during surface discharge is simulated.The experimental results show that the spectral intensity of the surface discharge of the SiR material is mainly concentrated at 350,600 and 750-900 nm bands.The spectral intensity reaches the maximum value when the ageing time is 168 h.With the intensification of ageing,no new characteristic peaks generate in the discharge spectrum,but the proportion of the same characteristic peaks to the overall wavelength is different.The type of discharge material and ageing state are determined by the characteristic light intensity ratio Ib.The evolutionary mechanism of the discharge spectrum is revealed by the variation of flashover voltage,trap charge density,resistivity and other parameters.The simulation results show that the increase of electron density will lead to more intense electron collision,which will release more photons,resulting in enhanced spectral intensity.This work can provide a reference for the detection of surface discharge and the evaluation of ageing state of the equipment inside the high voltage box.
