Research On Control Method Of Paralleledbreaking Based On Current-transfer Process

With the increase of stated grid capacity, the current under normal load increases during the process of grid operation. Meanwhile, the frequency of the occurrence of short-circuit fault and the value of short-circuit fault current both increase. The research on large capacity vacuum circuit breaker receives great attention from scholars at home and abroad. Since the bottlenecks of contact material and structure are difficult to break through, the rated flow capacity and fault current breaking capacity of the single fracture vacuum circuit breaker can't meet the breaking requirements for increasing short-circuit fault current of large rated current. The new mentality of using paralleled vacuum circuit breaker to undertake short circuit current is put forward by researchers. The current-transfer process and the basic principle of phase-control are discussed separately, the phase control scheme of paralleled vacuum circuit breaker which is designed on the basis of current-transfer process is studied subsequently.First of all, the current density, electro-dynamic force and temperature simulation of the symmetrical and unsymmetrical structure in single-phase are conducted by using the simulation software Ansoft Maxwell and ANSYS. Secondly, the more stable structure is chosen as the reference for test platform construction and the current transfer test is completed in high-voltage laboratory in Dalian University of Technology. Thirdly, the current-transfer simulation is conducted by using MATLAB and the influence of the branch impedance, time parameter and breaking time on current-transfer process is discussed respectively. The simulation and test results are contrasted so as to revise the current-transfer model, which provides the basis for phase control scheme. At last, the phase control scheme of paralleled structures are designed and verified.The current transfer process and the phase control scheme based on this process are discussed. The corresponding control theory is applied to solving the problem of insufficient breaking capacity of the single vacuum circuit breaker. And the mission of cutting off the short circuit fault in power grid accurately and timely is achieved. This task is based on the project of NSFC: The research on current-transfer breaking strategy and its regulation mechanism in vacuum. The mathematic model of current-transfer process and the current-transfer test are completed and the phase control scheme is discussed.