Based on the self-shrinkage effect of liquid metal,liquid-metal energy dissipators(LMEDs)have good applications in the energy absorption branch of a high-voltage DC system.However,LMEDs instantaneously produce large a...Based on the self-shrinkage effect of liquid metal,liquid-metal energy dissipators(LMEDs)have good applications in the energy absorption branch of a high-voltage DC system.However,LMEDs instantaneously produce large amounts of liquid-metal vapor during operation;therefore,the varying characteristics of the pressure in the cavity affect their energy consumption capacity and service life.In this study,the force and motion of liquid metal were analyzed,a mathematical model of shrinkage time before the arc was constructed,the influence of shortcircuit current and pore size on shrinkage time was explored,and the key factors affecting shrinkage time were clarified.Based on the theory of magnetohydrodynamics,the entire process of liquid metal from the beginning of contraction to the truncation of the arc was simulated to obtain the change characteristics of physical parameters,such as pressure and Lorentz force,in the cavity during the shrinkage process and to study the influence on contraction time by adjusting the short-circuit current and aperture size.A GaInSn liquid-metal energy dissipation test platform was built.The pre-arc shrinkage characteristics of the GaInSn liquid metal were studied,the variation in the voltammetry characteristic curve during liquid-metal energy dissipation was detected,and the accuracy of the simulation model was verified using experimental data.This study provides a theoretical reference for the application of LMEDs to power systems of different grades.展开更多
The synthetic making test has been widely used in evaluating the break ability of high-voltage circuit breaker. However, the test research and application are still inadequate, especially in the condition of rated vol...The synthetic making test has been widely used in evaluating the break ability of high-voltage circuit breaker. However, the test research and application are still inadequate, especially in the condition of rated voltage. According to the realistic conditions of test stations in China, a control device based on pre-arcing current detection and phase control is proposed in this paper. A sample of the control device made up of DSP TMS320LF2407A is fabricated, in which the CPLD MAX7064 is used to transmit signals for EMC design. It can be applied in full voltage synthetic making test at a level of 126kV/63kA. The test results show that, it is accurate to control the making phase of the applied voltage, whether the closing is demanded at voltage peak or zero.展开更多
电弧定向能量沉积(arc-based directed energy deposition,Arc-DED)技术在铝合金结构制造领域的地位日益凸显,具备独特优势与应用潜力。然而,由于铝合金的自身理化特性,热沉积过程极易产生氧化、变形、气孔等问题。同时,沉积过程的热量...电弧定向能量沉积(arc-based directed energy deposition,Arc-DED)技术在铝合金结构制造领域的地位日益凸显,具备独特优势与应用潜力。然而,由于铝合金的自身理化特性,热沉积过程极易产生氧化、变形、气孔等问题。同时,沉积过程的热量累积效应,可进一步增加沉积结构出现裂纹、形状塌陷和残余应力等问题的概率,严重制约了铝合金Arc-DED制造质量与生产效率的提升,极大限制了铝合金Arc-DED结构在相关工业领域的推广应用。围绕现代工业对铝合金Arc-DED提质增效提出的更高要求,从沉积过程的前、中、后三方面综述了优化能量输入、添加变质剂、引入辅助能场以及热处理等重要技术手段,分析了各类方法的优缺点和适用范围,并探讨了铝合金Arc-DED技术的未来发展方向,为平衡铝合金高性能构件生产制造的质效矛盾、推动铝合金Arc-DED技术高速发展提供了重要的理论指引与实践参考。展开更多
基于自收缩效应的液态金属限流器(liquid metal current limiter,LMCL)有自动检测限流、故障排除后可自恢复、填充介质对环境友好、结构简单以及体积小的独特优点,具有良好的应用前景。通过测量不同情况下限流过程回路电流以及LMCL的电...基于自收缩效应的液态金属限流器(liquid metal current limiter,LMCL)有自动检测限流、故障排除后可自恢复、填充介质对环境友好、结构简单以及体积小的独特优点,具有良好的应用前景。通过测量不同情况下限流过程回路电流以及LMCL的电弧电压,实验研究了LMCL限流特性的影响因素,为LMCL结构的优化设计提供参考依据。实验结果表明:LMCL的限流效果随着弧前时间的缩短以及电弧电压的上升而愈加明显,弧前时间和电弧电压受预期短路电流和LMCL结构参数的影响;同时实验过程中发现,大电流下电弧压力对LMCL限流性能会产生不利的影响,为解决此问题,提出了一种带有压力释放功能的限流器结构,可以有效地改善限流效果。展开更多
基金supported by the Excellent Young Scientists Fund of China(No.51922090)National Natural Science Foundation of China(Nos.U19A20105,U1966602,and 51837009)。
文摘Based on the self-shrinkage effect of liquid metal,liquid-metal energy dissipators(LMEDs)have good applications in the energy absorption branch of a high-voltage DC system.However,LMEDs instantaneously produce large amounts of liquid-metal vapor during operation;therefore,the varying characteristics of the pressure in the cavity affect their energy consumption capacity and service life.In this study,the force and motion of liquid metal were analyzed,a mathematical model of shrinkage time before the arc was constructed,the influence of shortcircuit current and pore size on shrinkage time was explored,and the key factors affecting shrinkage time were clarified.Based on the theory of magnetohydrodynamics,the entire process of liquid metal from the beginning of contraction to the truncation of the arc was simulated to obtain the change characteristics of physical parameters,such as pressure and Lorentz force,in the cavity during the shrinkage process and to study the influence on contraction time by adjusting the short-circuit current and aperture size.A GaInSn liquid-metal energy dissipation test platform was built.The pre-arc shrinkage characteristics of the GaInSn liquid metal were studied,the variation in the voltammetry characteristic curve during liquid-metal energy dissipation was detected,and the accuracy of the simulation model was verified using experimental data.This study provides a theoretical reference for the application of LMEDs to power systems of different grades.
文摘The synthetic making test has been widely used in evaluating the break ability of high-voltage circuit breaker. However, the test research and application are still inadequate, especially in the condition of rated voltage. According to the realistic conditions of test stations in China, a control device based on pre-arcing current detection and phase control is proposed in this paper. A sample of the control device made up of DSP TMS320LF2407A is fabricated, in which the CPLD MAX7064 is used to transmit signals for EMC design. It can be applied in full voltage synthetic making test at a level of 126kV/63kA. The test results show that, it is accurate to control the making phase of the applied voltage, whether the closing is demanded at voltage peak or zero.
文摘电弧定向能量沉积(arc-based directed energy deposition,Arc-DED)技术在铝合金结构制造领域的地位日益凸显,具备独特优势与应用潜力。然而,由于铝合金的自身理化特性,热沉积过程极易产生氧化、变形、气孔等问题。同时,沉积过程的热量累积效应,可进一步增加沉积结构出现裂纹、形状塌陷和残余应力等问题的概率,严重制约了铝合金Arc-DED制造质量与生产效率的提升,极大限制了铝合金Arc-DED结构在相关工业领域的推广应用。围绕现代工业对铝合金Arc-DED提质增效提出的更高要求,从沉积过程的前、中、后三方面综述了优化能量输入、添加变质剂、引入辅助能场以及热处理等重要技术手段,分析了各类方法的优缺点和适用范围,并探讨了铝合金Arc-DED技术的未来发展方向,为平衡铝合金高性能构件生产制造的质效矛盾、推动铝合金Arc-DED技术高速发展提供了重要的理论指引与实践参考。
文摘基于自收缩效应的液态金属限流器(liquid metal current limiter,LMCL)有自动检测限流、故障排除后可自恢复、填充介质对环境友好、结构简单以及体积小的独特优点,具有良好的应用前景。通过测量不同情况下限流过程回路电流以及LMCL的电弧电压,实验研究了LMCL限流特性的影响因素,为LMCL结构的优化设计提供参考依据。实验结果表明:LMCL的限流效果随着弧前时间的缩短以及电弧电压的上升而愈加明显,弧前时间和电弧电压受预期短路电流和LMCL结构参数的影响;同时实验过程中发现,大电流下电弧压力对LMCL限流性能会产生不利的影响,为解决此问题,提出了一种带有压力释放功能的限流器结构,可以有效地改善限流效果。
