Constrained by the characteristics of neutral sec- tions (NS) and traditional vacuum circuit breakers, previous phase-controlled strategies have a long power supply dead time, it is difficult to realize a continuous p...Constrained by the characteristics of neutral sec- tions (NS) and traditional vacuum circuit breakers, previous phase-controlled strategies have a long power supply dead time, it is difficult to realize a continuous power supply to the auxiliary power system. The dead time can be reduced by using the ground automatic convert method, hybrid phase-controlled technologies can in theory completely eliminate inrush currents. In this paper, a new system based on hybrid phase-controlled switches is described and termed ground-switching passing neutral section system (GPNSS). The principle for restraining inrush currents is analyzed and strategies are carried out with the dead time limited to 5 ms. The characteristics of the vacuum circuit breaker are illustrated and the closing time window of the transformer is quantified. Through the use of mechanical switches and power electronics, the auxiliary power system may be continuously pow- ered. The prototype system is implemented and experimentally tested in the laboratory.展开更多
简述了自动超声相控阵检测技术的发展、基本原理、特点及换能器分类等。将相控阵同衍射波时差法TOFD(Time of FlightD iffraction)、数字信号处理以及A,B,C,D型扫描和成像等技术结合起来,分析了其在海洋敷管环焊缝检测中的应用效果,在...简述了自动超声相控阵检测技术的发展、基本原理、特点及换能器分类等。将相控阵同衍射波时差法TOFD(Time of FlightD iffraction)、数字信号处理以及A,B,C,D型扫描和成像等技术结合起来,分析了其在海洋敷管环焊缝检测中的应用效果,在检测精度、检测速度、减少环境辐射污染、降低劳动强度等方面比其它检测方法有着明显的优势,具有良好的发展前景。展开更多
文摘Constrained by the characteristics of neutral sec- tions (NS) and traditional vacuum circuit breakers, previous phase-controlled strategies have a long power supply dead time, it is difficult to realize a continuous power supply to the auxiliary power system. The dead time can be reduced by using the ground automatic convert method, hybrid phase-controlled technologies can in theory completely eliminate inrush currents. In this paper, a new system based on hybrid phase-controlled switches is described and termed ground-switching passing neutral section system (GPNSS). The principle for restraining inrush currents is analyzed and strategies are carried out with the dead time limited to 5 ms. The characteristics of the vacuum circuit breaker are illustrated and the closing time window of the transformer is quantified. Through the use of mechanical switches and power electronics, the auxiliary power system may be continuously pow- ered. The prototype system is implemented and experimentally tested in the laboratory.
文摘简述了自动超声相控阵检测技术的发展、基本原理、特点及换能器分类等。将相控阵同衍射波时差法TOFD(Time of FlightD iffraction)、数字信号处理以及A,B,C,D型扫描和成像等技术结合起来,分析了其在海洋敷管环焊缝检测中的应用效果,在检测精度、检测速度、减少环境辐射污染、降低劳动强度等方面比其它检测方法有着明显的优势,具有良好的发展前景。
