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
Influence of the gassing materials, such as PA6, PMMA, and POM on the dielectric properties of air are investigated. In this work, the fundamental electron collision cross section data were carefully selected and vali...Influence of the gassing materials, such as PA6, PMMA, and POM on the dielectric properties of air are investigated. In this work, the fundamental electron collision cross section data were carefully selected and validated. Then the species compositions of the air–organic vapor mixtures were calculated based on the Gibbs free energy minimization. Finally, the Townsend ionization coefficient, the Townsend electron attachment coefficient and the critical reduced electric field strength were derived from the calculated electron energy distribution function by solving the Boltzmann transport equation. The calculation results indicated that H;O with large attachment cross sections has a great impact on the critical reduced electric field strength of the air–organic vapor mixtures. On the other hand, the vaporization of gassing materials can help to increase the dielectric properties of air circuit breakers to some degree.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.
基金supported by the National Key Basic Research Program of China(973 Program)2015CB251002National Natural Science Foundation of China under Grant 51521065,51577145+1 种基金the Fundamental Research Funds for the Central UniversitiesShaanxi Province Natural Science Foundation 2013JM-7010
文摘Influence of the gassing materials, such as PA6, PMMA, and POM on the dielectric properties of air are investigated. In this work, the fundamental electron collision cross section data were carefully selected and validated. Then the species compositions of the air–organic vapor mixtures were calculated based on the Gibbs free energy minimization. Finally, the Townsend ionization coefficient, the Townsend electron attachment coefficient and the critical reduced electric field strength were derived from the calculated electron energy distribution function by solving the Boltzmann transport equation. The calculation results indicated that H;O with large attachment cross sections has a great impact on the critical reduced electric field strength of the air–organic vapor mixtures. On the other hand, the vaporization of gassing materials can help to increase the dielectric properties of air circuit breakers to some degree.
