Transient enclosure voltage（TEV）,which is a phenomenon induced by the inner dielectric breakdown of SF_6 during disconnector operations in a gas-insulated switchgear（GIS）,may cause issues relating to shock hazard ...Transient enclosure voltage（TEV）,which is a phenomenon induced by the inner dielectric breakdown of SF_6 during disconnector operations in a gas-insulated switchgear（GIS）,may cause issues relating to shock hazard and electromagnetic interference to secondary equipment.This is a critical factor regarding the electromagnetic compatibility of ultra-high-voltage（UHV）substations.In this paper,the statistical characteristics of TEV at UHV level are collected from field experiments,and are analyzed and compared to those from a repeated strike process.The TEV waveforms during disconnector operations are recorded by a self-developed measurement system first.Then,statistical characteristics,such as the pulse number,duration of pulses,frequency components,magnitude and single pulse duration,are extracted.The transmission line theory is introduced to analyze the TEV and is validated by the experimental results.Finally,the relationship between the TEV and the repeated strike process is analyzed.This proves that the pulse voltage of the TEV is proportional to the corresponding breakdown voltage.The results contribute to the definition of the standard testing waveform of the TEV,and can aid the protection of electronic devices in substations by minimizing the threat of this phenomenon.展开更多
Very fast transient over-voltage （VFTO）, induced by disconnector operations in gas- insulated switchgears, has become the limiting dielectric stress at ultra-high voltage levels. Much work has been done to investiga...Very fast transient over-voltage （VFTO）, induced by disconnector operations in gas- insulated switchgears, has become the limiting dielectric stress at ultra-high voltage levels. Much work has been done to investigate single-strike waveforms of VFTO. However, little study has been carried out investigating the repeated strike process, which would influence VFTO significantly. In this paper, we carried out 450 effective experiments in an ultra-high voltage test circuit, and conducted calculations through the Monte Carlo simulation method, to investigate the repeated strike process. Firstly, the mechanism of the repeated strike process is proposed, based on the ex- perimentai results. Afterwards, statistical breakdown characteristics of disconnectors are obtained and analyzed. Finally, simulations of the repeated strike process are conducted, which indicate that the dielectric strength recovery speed and polarity effect factor have a joint effect on VFTO. This study enhances the understanding of the nature of VFTO, and may help to optimize the disconnector designed to minimize VFTO.展开更多
After the North China grid and the Central China grid get into connection with the UHVAC demonstration, a new phenomenon is discovered according to some simulations. That is, the faults at the remote end of the UHV in...After the North China grid and the Central China grid get into connection with the UHVAC demonstration, a new phenomenon is discovered according to some simulations. That is, the faults at the remote end of the UHV interconnected grid will result in significant power fluctuation and voltage drop on the UHV transmission line and even system splitting. But the faults near the UHV line only have marginal effects. Further, the simulation results also indicate that the short-circuit current of the buses near the UHV line is larger than that of the buses far away from the UHV line. This phenomenon is divergent from the traditional view. In this paper, the detail will be introduced, and the factors influencing the system stability after faults are presented and analyzed. The results indicate that transmission power of the UHV line and of the lines between the remote end and the major grid influence the fluctuation on UHV line. The load model and the grid structure of the remote end also have effect on it. Finally, corresponding control scheme is presented to improve the operation conditions of the UHV interconnected grid and ensure its security and stability.展开更多
特高压(ultra high voltage,UHV)换流站阀厅的金属屋面系统在风荷载作用下易发生屋面表层风揭事故。为深入探讨该类建筑屋面的风压极值特性,基于风洞试验分别探讨了大气边界层(atmospheric-boundary-layer,ABL)风、壁面射流、均匀湍流...特高压(ultra high voltage,UHV)换流站阀厅的金属屋面系统在风荷载作用下易发生屋面表层风揭事故。为深入探讨该类建筑屋面的风压极值特性,基于风洞试验分别探讨了大气边界层(atmospheric-boundary-layer,ABL)风、壁面射流、均匀湍流三种风场作用下的屋面风压特性,比较了平均风剖面、风速、风向、湍流强度等因素对屋面风压的影响。结果表明:阀厅屋盖迎风前缘负风压最大,且控制风向角在45°左右;壁面射流风场下平均风压系数与脉动风压系数均超过大气边界层风场的结果;风速对阀厅屋盖的负风压系数均值和极值影响较小,而湍流度对风压系数的极值影响较大;大气边界风场时,JGJ/T 481—2019《屋盖结构风荷载标准》的最不利风压系数建议值偏于安全;而在壁面射流风场下,阀厅屋盖全风向最不利风压系数在所有区域都大于JGJ/T 481—2019的建议值,设计中应加以重视。展开更多
可控型混合无功补偿(hybrid reactive power compensation,HRPC)对输电线路暂态特性的影响亟待研究。在分析可控型混合无功补偿结构功能的基础上,以晋东南-南阳-荆门特高压示范线路为背景,建立特高压混合无功补偿线路单相接地故障等效模...可控型混合无功补偿(hybrid reactive power compensation,HRPC)对输电线路暂态特性的影响亟待研究。在分析可控型混合无功补偿结构功能的基础上,以晋东南-南阳-荆门特高压示范线路为背景,建立特高压混合无功补偿线路单相接地故障等效模型,研究可控串联补偿+可控并联电抗器(thyristor controlled series compensation+thyristor controlled transformer,TSCT+TCT)混合无功补偿对断路器开断特性的影响。基于拉氏变换和等值参数集中电路,分析瞬态恢复电压(transient recovery voltage,TRV)影响因素,得出瞬态恢复电压随可控型混合无功补偿度变化规律。利用PSCAD/EMTDC,研究安装可控型混合无功补偿前后对瞬态恢复电压的影响,验证分析方法的有效性。结果表明:随着可控型混合无功补偿度的增加,TRV峰值和上升率R RRV不断增大,而TCT对瞬态恢复电压影响较小。展开更多
基金supported by the National Basic Research Program of China(973 Program) under grant 2011CB209405
文摘Transient enclosure voltage（TEV）,which is a phenomenon induced by the inner dielectric breakdown of SF_6 during disconnector operations in a gas-insulated switchgear（GIS）,may cause issues relating to shock hazard and electromagnetic interference to secondary equipment.This is a critical factor regarding the electromagnetic compatibility of ultra-high-voltage（UHV）substations.In this paper,the statistical characteristics of TEV at UHV level are collected from field experiments,and are analyzed and compared to those from a repeated strike process.The TEV waveforms during disconnector operations are recorded by a self-developed measurement system first.Then,statistical characteristics,such as the pulse number,duration of pulses,frequency components,magnitude and single pulse duration,are extracted.The transmission line theory is introduced to analyze the TEV and is validated by the experimental results.Finally,the relationship between the TEV and the repeated strike process is analyzed.This proves that the pulse voltage of the TEV is proportional to the corresponding breakdown voltage.The results contribute to the definition of the standard testing waveform of the TEV,and can aid the protection of electronic devices in substations by minimizing the threat of this phenomenon.
基金supported in part by National Natural Science Foundation of China(No.51277106)in part by the National Basic Research Program of China(973 Program)(No.2011CB209405)
文摘Very fast transient over-voltage （VFTO）, induced by disconnector operations in gas- insulated switchgears, has become the limiting dielectric stress at ultra-high voltage levels. Much work has been done to investigate single-strike waveforms of VFTO. However, little study has been carried out investigating the repeated strike process, which would influence VFTO significantly. In this paper, we carried out 450 effective experiments in an ultra-high voltage test circuit, and conducted calculations through the Monte Carlo simulation method, to investigate the repeated strike process. Firstly, the mechanism of the repeated strike process is proposed, based on the ex- perimentai results. Afterwards, statistical breakdown characteristics of disconnectors are obtained and analyzed. Finally, simulations of the repeated strike process are conducted, which indicate that the dielectric strength recovery speed and polarity effect factor have a joint effect on VFTO. This study enhances the understanding of the nature of VFTO, and may help to optimize the disconnector designed to minimize VFTO.
文摘After the North China grid and the Central China grid get into connection with the UHVAC demonstration, a new phenomenon is discovered according to some simulations. That is, the faults at the remote end of the UHV interconnected grid will result in significant power fluctuation and voltage drop on the UHV transmission line and even system splitting. But the faults near the UHV line only have marginal effects. Further, the simulation results also indicate that the short-circuit current of the buses near the UHV line is larger than that of the buses far away from the UHV line. This phenomenon is divergent from the traditional view. In this paper, the detail will be introduced, and the factors influencing the system stability after faults are presented and analyzed. The results indicate that transmission power of the UHV line and of the lines between the remote end and the major grid influence the fluctuation on UHV line. The load model and the grid structure of the remote end also have effect on it. Finally, corresponding control scheme is presented to improve the operation conditions of the UHV interconnected grid and ensure its security and stability.
文摘特高压(ultra high voltage,UHV)换流站阀厅的金属屋面系统在风荷载作用下易发生屋面表层风揭事故。为深入探讨该类建筑屋面的风压极值特性,基于风洞试验分别探讨了大气边界层(atmospheric-boundary-layer,ABL)风、壁面射流、均匀湍流三种风场作用下的屋面风压特性,比较了平均风剖面、风速、风向、湍流强度等因素对屋面风压的影响。结果表明:阀厅屋盖迎风前缘负风压最大,且控制风向角在45°左右;壁面射流风场下平均风压系数与脉动风压系数均超过大气边界层风场的结果;风速对阀厅屋盖的负风压系数均值和极值影响较小,而湍流度对风压系数的极值影响较大;大气边界风场时,JGJ/T 481—2019《屋盖结构风荷载标准》的最不利风压系数建议值偏于安全;而在壁面射流风场下,阀厅屋盖全风向最不利风压系数在所有区域都大于JGJ/T 481—2019的建议值,设计中应加以重视。
基金Project supported by Funds for Innovative Research Groups of China （51021005）, National Basic Research Program of China （973 Program） （2009CB724504）, National Natural Science Foundation of China（50707036）.
