The electric field imposes a significant effect on ice accretion on the insulator.The impact of an AC electric field on insulator icing in an artificial climate chamber has been addressed.Compared with AC,DC electric ...The electric field imposes a significant effect on ice accretion on the insulator.The impact of an AC electric field on insulator icing in an artificial climate chamber has been addressed.Compared with AC,DC electric field exerts an attraction on supercooled water droplets,which is more detrimental to the power system.Moreover,the icing on energised insulators is rarely studied in the natural environment.In the present research,an electrical,fluid coupled‐field simulation was carried out on the insulator.The force characteristics and motion deviation features of water droplets at different positive DC electric field strengths were studied.On this basis,rime icing on the insulator energised with different positive DC voltages was investigated in the field.Results show that the charged droplet shifts along the electric field line under a positive DC voltage.The deviation degree of the droplet increases with the increment of the voltage and droplet size and decreases with an increase in wind speed.As the voltage rises,the surface roughness,icing amount and icing length of rime ice‐covered insulator increase.Consequently,compared with that without energisation,the local collision coefficient,icing amount and icing length increase by 17.6%,46.4%and 63.9%,respectively,under a 40 kV DC voltage.展开更多
Outlet short circuit on the low-voltage(LV)side and winding inter-turn short circuit faults are hazardous to transformer operation.To investigate the formation mechanism of winding insulation faults of distribution tr...Outlet short circuit on the low-voltage(LV)side and winding inter-turn short circuit faults are hazardous to transformer operation.To investigate the formation mechanism of winding insulation faults of distribution transformer,ANSYS Maxwell was used to build a coupled magnetic field-circuit model with the same structural dimension as the actual distribution transformer.An outlet short circuit and winding inter-turn insulation faults were set by using the voltage-controlled switch in the external circuit of the model.Sub-sequently,the differences in the electromagnetic characteristics and the electrodynamic force distributions of the windings under three operating conditions,namely,nominal load,three-phase outlet short circuit on the LV side and inter-turn insulation failure were studied,respectively.The results show that compared with the rated load,in the cases of outlet short circuit and inter-turn insulation faults,the amplitude of winding current in-creases by 20 and 50 times,the magnetic field strength grows by 20 and 17 times,and the electrodynamic force rises by 400 and 230 times,respectively.Outlet short circuit fault is more likely to cause the winding instability and deformation,and inter-turn short circuit fault can easily burn out winding insulation.Therefore,corresponding preventive measures were proposed.展开更多
Recently,various slippery liquid-infused porous surfaces(SLIPS)have been fabricated for the protection of various materials.However,these SLIPSs are limited by their underlying storage structure and superficial lubric...Recently,various slippery liquid-infused porous surfaces(SLIPS)have been fabricated for the protection of various materials.However,these SLIPSs are limited by their underlying storage structure and superficial lubricant layer,showing poor durability.Herein,inspired by the high-strength structure of Shell nacre’s“brick-mud”layer,we fabricated an all-inorganic composite coating by using wet chemically etched MXene as a brick and an aluminum phosphate binder(AP)as mud.Then,a series of microwell-array structures were designed and prepared on the coating via nanosecond ultrafast laser writing ablation technology.Subsequently,the textured surface was modified by a silane coupling agent.Vinyl-terminated polydimethylsiloxane(PDMS)was tightly grafted onto the porous surface through a thiol-ene click reaction to obtain lubricant grafted texture surface(LGTS).The prepared LGTS showed good lubrication properties for multiple phases,including various liquids,ice crystals,and solids.It exhibits excellent chemical stability and mechanical durability under deionized water impact,centrifugal test,strong acid solutions,anti/de-icing cycles,and high-intensity friction.Thus,the proposed strategy for constructing robust LGTS will greatly promote theoretical research on super wetting interfacial materials and their applications in the fields of antifouling,anti/de-icing,and lubricating protection.展开更多
基金National Natural Science Foundation of China,Grant/Award Number:51907109。
文摘The electric field imposes a significant effect on ice accretion on the insulator.The impact of an AC electric field on insulator icing in an artificial climate chamber has been addressed.Compared with AC,DC electric field exerts an attraction on supercooled water droplets,which is more detrimental to the power system.Moreover,the icing on energised insulators is rarely studied in the natural environment.In the present research,an electrical,fluid coupled‐field simulation was carried out on the insulator.The force characteristics and motion deviation features of water droplets at different positive DC electric field strengths were studied.On this basis,rime icing on the insulator energised with different positive DC voltages was investigated in the field.Results show that the charged droplet shifts along the electric field line under a positive DC voltage.The deviation degree of the droplet increases with the increment of the voltage and droplet size and decreases with an increase in wind speed.As the voltage rises,the surface roughness,icing amount and icing length of rime ice‐covered insulator increase.Consequently,compared with that without energisation,the local collision coefficient,icing amount and icing length increase by 17.6%,46.4%and 63.9%,respectively,under a 40 kV DC voltage.
基金National Natural Science Foundation of China,Grant/Award Number:52077221。
文摘Outlet short circuit on the low-voltage(LV)side and winding inter-turn short circuit faults are hazardous to transformer operation.To investigate the formation mechanism of winding insulation faults of distribution transformer,ANSYS Maxwell was used to build a coupled magnetic field-circuit model with the same structural dimension as the actual distribution transformer.An outlet short circuit and winding inter-turn insulation faults were set by using the voltage-controlled switch in the external circuit of the model.Sub-sequently,the differences in the electromagnetic characteristics and the electrodynamic force distributions of the windings under three operating conditions,namely,nominal load,three-phase outlet short circuit on the LV side and inter-turn insulation failure were studied,respectively.The results show that compared with the rated load,in the cases of outlet short circuit and inter-turn insulation faults,the amplitude of winding current in-creases by 20 and 50 times,the magnetic field strength grows by 20 and 17 times,and the electrodynamic force rises by 400 and 230 times,respectively.Outlet short circuit fault is more likely to cause the winding instability and deformation,and inter-turn short circuit fault can easily burn out winding insulation.Therefore,corresponding preventive measures were proposed.
基金supported by the National Natural Science Foundation of China(No.52205313)Natural Science Foundation of Shandong Province(ZR2022QE161),China Postdoctoral Science Foundation(2023M734093)+1 种基金the Tribology Science Fund of State Key Laboratory of Solid Lubrication(LSL-2312)Scientific Innovation Project for Young Scientists in Shandong Provincial Universities(2023KJ145,2023KJ148).
文摘Recently,various slippery liquid-infused porous surfaces(SLIPS)have been fabricated for the protection of various materials.However,these SLIPSs are limited by their underlying storage structure and superficial lubricant layer,showing poor durability.Herein,inspired by the high-strength structure of Shell nacre’s“brick-mud”layer,we fabricated an all-inorganic composite coating by using wet chemically etched MXene as a brick and an aluminum phosphate binder(AP)as mud.Then,a series of microwell-array structures were designed and prepared on the coating via nanosecond ultrafast laser writing ablation technology.Subsequently,the textured surface was modified by a silane coupling agent.Vinyl-terminated polydimethylsiloxane(PDMS)was tightly grafted onto the porous surface through a thiol-ene click reaction to obtain lubricant grafted texture surface(LGTS).The prepared LGTS showed good lubrication properties for multiple phases,including various liquids,ice crystals,and solids.It exhibits excellent chemical stability and mechanical durability under deionized water impact,centrifugal test,strong acid solutions,anti/de-icing cycles,and high-intensity friction.Thus,the proposed strategy for constructing robust LGTS will greatly promote theoretical research on super wetting interfacial materials and their applications in the fields of antifouling,anti/de-icing,and lubricating protection.
