Research On The Characteristics Of Breaking And Post-arc Of Direct Circuit Vacuum Circuit Breaker With Double-breaks

With the development of new energy technology,direct circuit(DC)systems have become the first choice for energy transmission.DC breaker is one of the core components in the construction of DC systems,which undertakes multiple tasks of system controls and protections.The breaking performance of DC breaker is vital to the safety,the reliability and the stable operation of the system.In this dissertation,DC fault breaker of DC vacuum circuit breaker(VCB)is the research focus.With the theoretical analysis and experiments,the protections and adjusting and controlling mechanisms of DC fault breaker have been studied.And the topological parameters of the commutation circuit,the influences of converter frequency and line impedance on the breaking performance and its dynamic insulation characteristics have been studied.Then the establishment of experiment platforms for DC VCB and the influence mechanisms of post-arc medium recover under the different line parameters have been analyzed.The research is on the adjusting and controlling methods to the post-arc medium recover of DC VCB.By the continuous transition models(CTM),metallic vapor particle fluid models,the simulation models of medium recover of DC VCB with Double-breaks are built and the dynamic process of its medium recover are analyzed by simulation.The physics-maths models with the macro-circuit and micro-back-arc parameter are built.With the heavy breakdown theory,the influences of the main factors at various stages for medium recover and the line parameters on arcing are studied.The research is on the experiments of DC VCB with Double-breaks.The changing principles and the arc dynamics acquired under the intermediate frequency of DC VCB with Double-breaks are analyzed with the arc image technology and experimental parameter.The influential factors and empty responses between the two models of DC VCB with Double-breaks are analyzed quantitatively with the integration of the mechanism characteristics and the arc properties.The sequence control models adjusting and controlling the coordinations of different models,the zero dynamic behaviors of the vacuum arcs under the various gaps,the distributions of arc energy at the breaks,the post-arc medium recover and the distributions of voltage are studied.The researchers are on the breaking performance differences of Double-breaks with nonsynchronous operations and the post-arc medium recover characteristics.The physics-maths models of Double-breaks with non-synchronous break are built.The arc energy distribution,the metal vapor particle density on the development speed of the post-arc sheath,the electric field strength and power density of the new cathode surface under various gap differences are analyzed quantitatively.Studies have shown that the essential differences between the arc of DC VCB with Double-breaks and the post-arc characteristics are the gap differences which generates the differences in arc energy of breaks,charged particles,and metal vapor particles,dynamic insulation capabilities and the uneven distributions of post-arc voltage.The research is on the fault tolerance of DC VCB with Double-breaks and its breaking performance.A simulation calculation model of the DC VCB with Double-breaks is established and the simulation calculation is implemented on the different critical values for nonsynchronous break under the typical parameters.The research is on the critical values under the gap differences of DC VCB with Double-breaks and its synchronous breaking performance.The studies have shown that the critical values have the positive relationships with the breaking current and the reverse current input time.The limit concepts of DC VCB with Double-breaks delay-time break have been proposed after the experiments and simulation calculations on the topological structures,the arc properties,breaking performance and the medium recover ability.The breaking ability of DC VCB with Double-breaks and the dynamic insulating ability have been improved after altering topological parameter and mechanism characteristics to better its fault tolerance,which provides theoretical supports and experimental references for the DC VCB to integrate with the heavy current and high voltage.