Impedance composite superconducting fault current limiter based on novel superconducting material

Abstract

The invention discloses an impedance composite superconducting fault current limiter based on a novel superconducting material. The superconducting fault current limiter comprises a square iron core (18), wherein an MgB2 superconducting winding (11) is arranged on the upper side of the iron core (18) and connected with a reactor (10) in parallel; a high temperature superconducting winding (17) isarranged on the lower side of the iron core (18) and connected with a direct current voltage source (13) in series; and a magnetic switch (16) and a value adjustable first resister (12) are connectedin series between the high temperature superconducting winding (17) and the direct current voltage source (13) to form a first circuit. Under the condition of satisfying the line current-carrying capacity, the superconducting fault current limiter uses the fewest superconductors, can improve the inductive impedance level in case of fault, and also can reduce voltage loss in normal operation and ensure the reliability of operation.

Description

technical field [0001] The invention relates to a superconducting fault current limiter, in particular to an impedance composite superconducting fault current limiter based on a novel superconducting material, which belongs to the technical field of electric equipment. Background technique [0002] With the increasing scale of the power grid, short-circuit current has become one of the problems that plague the power system and seriously affect the safety and reliability of the power grid. In recent years, the superconducting fault current limiter has become a research frontier and a hot topic at home and abroad. A large number of applications of superconducting fault current limiters in power systems depend on the development of superconducting wires. The research and development of new superconductors with low price, easy processing, and higher critical temperature and current density has very important practical significance for the practical application of superconductin...

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Problems solved by technology

When the power grid is working normally, the AC coils 5 and 6 connected in series in the power grid present a low inductance state because the iron core is in a state of magnetic saturation; when a short-circuit fault occurs in the system, the instantaneously increased current makes the magnetic field generated by the AC coils 5 and 6 enough to offset The magnetic field generated by the DC bias coils 8 and 9 makes the two iron cores alternately enter the normal state from the saturation state, resulting in high impedance, which automatically limits the increase of the short-circuit current in the power grid

The AC windings 5 ​​and 6 of the saturated core type superconducting fault current limiter use copper windings. During normal operation, the primary copper windings have power loss. Although the more turns of the primary copper windings, the stronger the current limiting inductance, the better the effect, but The more turns, the resistance on the copper winding cannot be ignored, and the voltage drop on the superconducting fault current limiter will be larger during normal operation, which cannot reflect that the superconducting fault current limiter is connected in series to the power grid during normal operation. The advantages of influence; although the secondary side also uses superconducting windings, the superconducting material does not quench before and after the power grid fails, so the saturated core type superconducting fault current limiter cannot make good use of the superconducting material quenching After the advantage of the high resistance value

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