The study result on insulation coordination of ±1 000 kV and higher voltage grade ultra-high voltage(UHV) DC converter stations is presented.Aiming at the ±1 000 kV UHVDC system,influences on arrester config...The study result on insulation coordination of ±1 000 kV and higher voltage grade ultra-high voltage(UHV) DC converter stations is presented.Aiming at the ±1 000 kV UHVDC system,influences on arrester configuration and converter transformers insulation levels of converters' connections are discussed based on three schemes of serial converters structure: 500 kV+500 kV scheme,667 kV+333 kV scheme and 400 kV+400 kV+200 kV scheme.Comparing with the 500 kV+500 kV scheme,the 667 kV+333 kV scheme cannot reduce the maximum insulation level significantly and would bring problems to valve hall layout and operation controlling.The 400 kV+400 kV+200 kV scheme has no economic advantage as it increases land occupation and amount of equipments.According to comprehensive comparison,the 500 kV +500 kV scheme is recommended for ±1 000 kV UHVDC projects,and it is also suitable for higher voltage grade DC systems.According to system conditions of 1 100 kV,the switching impulse withstanding level(SIWL) of 2 100 kV and the lightning impulse withstanding level(LIWL) of 2 350 kV are feasible for ±1 100 kV UHVDC project,judging from the insulation levels.Meanwhile,arresters with higher performance are needed.展开更多
Vehicles operating in space need to withstand extreme thermal and electromagnetic environments in light of the burgeoning of space science and technology.It is imperatively desired to high insulation materials with li...Vehicles operating in space need to withstand extreme thermal and electromagnetic environments in light of the burgeoning of space science and technology.It is imperatively desired to high insulation materials with lightweight and extensive mechanical properties.Herein,a boron-silica-tantalum ternary hybrid phenolic aerogel(BSiTa-PA)with exceptional thermal stability,extensive mechanical strength,low thermal conductivity(49.6 mW m^(-1)K^(-1)),and heightened ablative resistance is prepared by an expeditious method.After extremely thermal erosion,the obtained carbon aerogel demonstrates noteworthy electromagnetic interference(EMI)shielding performance with an efficiency of 31.6 dB,accompanied by notable loading property with specific modulus of 272.8 kN·m kg^(-1).This novel design concept has laid the foundation for the development of insulation materials in more complex extreme environments.展开更多
One of the fundamental issues in gas insulated substations （GIS） which has destructive effects on GIS equipment is the very fast transient over-voltages （VFTOs）. This paper models a 400/230 kV substation in order ...One of the fundamental issues in gas insulated substations （GIS） which has destructive effects on GIS equipment is the very fast transient over-voltages （VFTOs）. This paper models a 400/230 kV substation in order to study the effects of VFTO extensively implemen- ted on EMTP-RV. In addition, the application of ferrite rings for suppressing VFTOs is assessed thoroughly. The main advantage of this paper is its new proposed algorithm according to the ferrite ring frequency dependent modeling that is validated with experimental results. This paper examines the effects of three compositions of the ferrite ring on VFTO suppression. Moreover, it estimates the dimension of the ferrite ring based on the SF6 gas insulation withstand and the maximum effect of ferrite rings on VFTO suppression constraint with the COMSOL multiphysics software. Furthermore, it gains VFTO attenuated percentages due to the installation of the ferrite ring in different GIS nodes. Finally, it analyzes the offered VFTO amendment technique in various GIS switching scenarios.展开更多
In order to specify the overvoltage and insulation level of equipments in ±1 100 kV UHVDC converter stations,the arrester configuration scheme and some basic parameters for ±1 100 kV Zhundong converter stati...In order to specify the overvoltage and insulation level of equipments in ±1 100 kV UHVDC converter stations,the arrester configuration scheme and some basic parameters for ±1 100 kV Zhundong converter station are proposed.Overvoltage of equipments in AC system,valve hall,DC busbar,and neutral busbar are also calculated in accordance with the fundamental principles of arrester configuration for UHV converter stations and the existing experiences in insulation coordination of ±800 kV UHVDC converter stations.The work is done also for specifing insulation levels for ±1 100 kV UHVDC converter stations of the ±1 100 kV UHVDC power transmission project from Zhundong to Sichuan in China.Thus,the recommended insulation margins that determine the insulation levels of converter station equipments are proposed: the insulation margins for thyristor valves are 10%/10%/15% for switching impulse/ lightning impulse/ steer front impulse; the insulation levels of lighting and swtiching impulses are recommended as 2 600 kV and 2 150 kV respectively for 1 100 kV DC buses,and as 2 250 kV and 2 100 kV respectively for equipments at the valve side of high-voltage Y/Y converter transformers.展开更多
基金Project supported by Science and Technology Project of SGCC(B3443411K001)
文摘The study result on insulation coordination of ±1 000 kV and higher voltage grade ultra-high voltage(UHV) DC converter stations is presented.Aiming at the ±1 000 kV UHVDC system,influences on arrester configuration and converter transformers insulation levels of converters' connections are discussed based on three schemes of serial converters structure: 500 kV+500 kV scheme,667 kV+333 kV scheme and 400 kV+400 kV+200 kV scheme.Comparing with the 500 kV+500 kV scheme,the 667 kV+333 kV scheme cannot reduce the maximum insulation level significantly and would bring problems to valve hall layout and operation controlling.The 400 kV+400 kV+200 kV scheme has no economic advantage as it increases land occupation and amount of equipments.According to comprehensive comparison,the 500 kV +500 kV scheme is recommended for ±1 000 kV UHVDC projects,and it is also suitable for higher voltage grade DC systems.According to system conditions of 1 100 kV,the switching impulse withstanding level(SIWL) of 2 100 kV and the lightning impulse withstanding level(LIWL) of 2 350 kV are feasible for ±1 100 kV UHVDC project,judging from the insulation levels.Meanwhile,arresters with higher performance are needed.
基金the support from the Joint Fund of Advanced Aerospace Manufacturing Technology Research of National Natural Science Foundation of China(U1837601)National Natural Science Foundation of China(52273255)+3 种基金NASF Joint Fund of National Natural Science Foundation of China and China Academy of Engineering Physics(U2130118)China Postdoctoral Science Foundation(2023M732029)Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX2023092)Undergraduate Innovation&Business Program in Northwestern Polytechnical University(XN2022226)。
文摘Vehicles operating in space need to withstand extreme thermal and electromagnetic environments in light of the burgeoning of space science and technology.It is imperatively desired to high insulation materials with lightweight and extensive mechanical properties.Herein,a boron-silica-tantalum ternary hybrid phenolic aerogel(BSiTa-PA)with exceptional thermal stability,extensive mechanical strength,low thermal conductivity(49.6 mW m^(-1)K^(-1)),and heightened ablative resistance is prepared by an expeditious method.After extremely thermal erosion,the obtained carbon aerogel demonstrates noteworthy electromagnetic interference(EMI)shielding performance with an efficiency of 31.6 dB,accompanied by notable loading property with specific modulus of 272.8 kN·m kg^(-1).This novel design concept has laid the foundation for the development of insulation materials in more complex extreme environments.
文摘One of the fundamental issues in gas insulated substations （GIS） which has destructive effects on GIS equipment is the very fast transient over-voltages （VFTOs）. This paper models a 400/230 kV substation in order to study the effects of VFTO extensively implemen- ted on EMTP-RV. In addition, the application of ferrite rings for suppressing VFTOs is assessed thoroughly. The main advantage of this paper is its new proposed algorithm according to the ferrite ring frequency dependent modeling that is validated with experimental results. This paper examines the effects of three compositions of the ferrite ring on VFTO suppression. Moreover, it estimates the dimension of the ferrite ring based on the SF6 gas insulation withstand and the maximum effect of ferrite rings on VFTO suppression constraint with the COMSOL multiphysics software. Furthermore, it gains VFTO attenuated percentages due to the installation of the ferrite ring in different GIS nodes. Finally, it analyzes the offered VFTO amendment technique in various GIS switching scenarios.
基金supported by National Basic Research Program of China(973 Program)(2011CB209405)
文摘In order to specify the overvoltage and insulation level of equipments in ±1 100 kV UHVDC converter stations,the arrester configuration scheme and some basic parameters for ±1 100 kV Zhundong converter station are proposed.Overvoltage of equipments in AC system,valve hall,DC busbar,and neutral busbar are also calculated in accordance with the fundamental principles of arrester configuration for UHV converter stations and the existing experiences in insulation coordination of ±800 kV UHVDC converter stations.The work is done also for specifing insulation levels for ±1 100 kV UHVDC converter stations of the ±1 100 kV UHVDC power transmission project from Zhundong to Sichuan in China.Thus,the recommended insulation margins that determine the insulation levels of converter station equipments are proposed: the insulation margins for thyristor valves are 10%/10%/15% for switching impulse/ lightning impulse/ steer front impulse; the insulation levels of lighting and swtiching impulses are recommended as 2 600 kV and 2 150 kV respectively for 1 100 kV DC buses,and as 2 250 kV and 2 100 kV respectively for equipments at the valve side of high-voltage Y/Y converter transformers.
