Novel magnetic shielding air-core transformer coupling bridge type solid state fault current limiter

Abstract

The invention discloses a novel magnetic shielding air-core transformer coupling bridge type solid state fault current limiter. The fault current limiter comprises an air-core transformer provided with a high temperature superconducting magnetic shielding barrel or winding, a rectifier bridge circuit and a direct current inductor. Compared with fault current limiters in prior art, the fault current limiter has the advantages that the size is small, the structure is compact, during a normal operation, due to a magnetic shielding effect of the superconducting magnetic shielding barrel, the impedance is extremely low, the influence of the impedance on a system can be completely ignored, when a fault happens, an automatic response is achieved, a high current-limiting impedance is inserted to limit the current rapidly, restoring time is short, and the improvement of system dynamic stability is facilitated.

Description

technical field [0001] The invention relates to a fault current limiter used in a power system, in particular to a magnetically shielded air-core transformer coupled bridge-type solid-state current limiter. Background technique [0002] With the continuous expansion of the scale of the power system and the development of grid interconnection, the level of short-circuit current in the grid continues to increase, and the escalating short-circuit faults cause more and more serious damage to electrical equipment in the grid, and at the same time gradually exceed the fault protection of power lines. The breaking capacity of the functioning circuit breaker poses a serious threat to the safety of the system operation. In order to ensure the safe operation of the system, it is necessary to continuously increase the capacity of electrical equipment such as transformers, generators, circuit breakers, and busbars in the system, resulting in an increase in the volume, weight, and cost o...

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Problems solved by technology

However, it should be noted that the iron core is deeply saturated when the short-circuit current is limited. Especially when the short-circuit current is too large, the magnetic permeability of the iron core is close to that of air. In order to effectively limit the short-circuit current by the excitation reactance, the number of winding turns must be increased. To ensure that the excitation reactance reaches the required value for current limiting, this will increase the primary side leakage reactance of the transformer at the same time, which will have a certain impact on the normal operation of the system

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