Fault current-limiting device for transmission and distribution electric network

Abstract

The circuit is installed at line outlet of electric power system and cascaded to a breaker. The circuit comprises four pair of controlled silicons paralleled in positive and negative direction and cascaded pairwise. The said circuit of silicons is connected to an equivalent current source in parallel. The invention possesses features of high efficiency, simple structure, reliable, solves too large failure current of electric system as well as lowers current tolerance for requiring each electric component, and design specification of system. The circuit raises stability, safety and reliability if it is utilized in high voltage or supervoltage transmission.

Description

Technical field: [0001] The invention relates to a fault current limiter for transmission and distribution network, which belongs to the technical field of electric engineering. Background technique: [0002] Due to the development of the power system, the increase of load, the investment of large-capacity units, power plants and substation equipment, especially the emergence of large power plants in the load center and the interconnection of large power systems, the capacity of the transmission and distribution network has been greatly increased, and at the same time, the short-circuit The current level is increasing day by day, and even the short-circuit current level in some places has exceeded the breaking capacity of the current circuit breaker. If no restrictive measures are taken to control it, not only will the equipment investment of the new substation be greatly increased, but it will also have a great impact on the original substation equipment in the system, and ...

AI Technical Summary

Problems solved by technology

Since the short-circuit protection circuit is rectified, the current flows through the equivalent current source, that is, the inductor in a single phase, which makes the inductor current be charged before the fault is removed, so the capacity of the inductor is very large, and with the increase of the inductor current, the inductor is charged. The time in series with the voltage source circuit is getting shorter and shorter, which makes the current limiting effect worse and worse until the current limiting effect is lost, that is, this protection circuit cannot limit the steady-state fault current

Moreover, if it is used in the transmission and distribution network, the short-circuit protection switch SW, whether it is an electronic switch or an electrical switch, the former has a very large capacity, and it needs to break off the fault current with a very large current change rate, and the reliability is poor during the breaking period; if it is the latter, The breaking time is too long, the current limiting effect is poor, and the breaking capacity of the electrical switch is also a big problem due to the gradual increase of the fault current

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