A Study Of Superconducting Fault Current Limiter’s Influence On Reclosing

Development of the electric power system is accompanied by a constant increasein short circuit breaking capacity and fault currents. As a consequence, exorbitantfault current would not only cause difficulties in the selection of circuit breaker, butalso pose threat to the stability and safe operation of the power grid. In order to cutthe short-current to the lower level when the control equipment of power system canbreak, during the last few years, a number of programs have been sponsored toinvestigate various techniques and devices applicable to limit fault currents in powersystems. The most ideal one of such devices is the superconducting fault currentlimiting devices. It works naturally and is self-examination, self-triggered,self-operation and self-restore. Study on the compatible problem of SFCL andconventional power system, to promote the industrialization of SFCL, improve thestability, security and reliability of the power system, and better serve the nationaleconomy and the people’s life, which has important theoretical significance andapplication value.This paper study the influence on reclosing operation considering the applicationof the SFCL and the S/N transition type SFCL in a power distribution system. Themagnetic-shield inductive SFCL and the rectifier bridge type SFCL are studied andimproved． The working principle and mathematical model of magnetic-shieldinductive SFCL and the rectifier bridge type SFCL is introduced. The new designmethod by MATLAB simulation that we put forward in this paper is the constructionof a single power system, the analysis on the characteristic of the power system andthe selection of SFCL to limit the fault current. When transient fault of power systemoccurs, it is studied on the effects of the two kinds of SFCL on the load voltage afterreclosing by MATLAB simulation. The result shows that load voltage is reduced andunbalanced considering the S/N transition type SFCL in power system, which led toreclosing failed. In order to solve this problem, this paper proposes a quench detectionsystem which can monitor the state of superconductor in real time. Reclosing takeaction only when superconductor get back to superconducting state. Simulate thevoltage of load, the results show that it can solve the problem that the S/N transition type SFCL can’t cooperate with reclosing while a quench detection system wasintroduced.All works above not only in terms of theory and simulation demonstrate theeffect of SFCL on automatic reclosing, but also make fundamental effort for followingexploration of the products based on SFCL.