The Development And Experiment Of 400V/20A Superconducting Magnetic Flux Constraint Fault Current Limiter Prototype

Since the development of economy and the increasing demand of electricity, the electric energy transferred through power grid increases rapidly. The short circuit current value becomes higher. Short circuit faults seriously impede the operation of equipment and personal safety of operators. The current circuit breaker has been unable to cut off the short circuit fault in power system effectively in regional power grid of China now. The requirement of the power equipment in electrical and thermal stability parameters is higher as the rise of the short circuit current value. And it needs better performance of the circuit breaker to interrupt short circuit current. Superconducting fault current limiter(SCFCL), which is made of superconducting materials, is an ideal current limiting device to limit the short-circuit current, protect the power grid equipment and maintain the stability of the power grid. While the power grid works normally, the current limiter has no effect on the system. When short circuit fault occurs, the impedance of the superconducting fault current limiter(SCFCL) increases to suppress the short-circuit current and maintain the stability of the power network. In this paper, a new type of magnetic flux constrained current limiter is proposed. The new current limiter consists of high coupled shunt inductance produced by superconducting materials. The short-circuit current will be limited while the inductance decoupling to increase the impedance of the current limiter. Main work done is as follows:(1) A new type of magnetic flux constraint superconducting fault current limiter is proposed. The high coupling inductance of the current limiter is manufactured by superconducting tape. As soon as the short circuit fault occurs, the impedance of the current limiter increases after the decoupling of the inductance to limit current. And the principle is verified by the simulation software.(2) Based on the coupling method of inductors, three different kinds of processing schemes are proposed. And they are all analyzed by the finite element simulation software to compare the magnetic field distribution under different conditions. The optimal geometric size of superconducting magnet is identified to guarantee the current limiting impedance.(3) The voltage distribution calculation of three kinds of coupling modes is carried out by means of multi-field coupling analysis method. The voltage distribution and the current limiting effect under different conditions are compared to confirm the final implementation of the program.(4) According to the simulation and design parameters, the superconducting fault current magnet is processed. The control circuit is built to control switch on and off remotely. The experimental data is recorded and analyzed during the circuit current limiting test. The results show that the new scheme is feasible and the current limiting effect is obvious.