Three-phase current limiting device and method

Abstract

The invention relates to a three-phase current limiting device and a three-phase current limiting method. The device comprises three magnetic saturation reactors, three current transformers, three pairs of reverse parallel thyristors, a three-phase bridge type rectifying circuit and a control circuit, wherein the three magnetic saturation reactors are provided with reactance coils L1 and direct current coils L2 respectively; the three current transformers are provided with primary coils L3 and secondary coils L4 respectively; the three pairs of reverse parallel thyristors are connected in parallel with the secondary coil L4 of each current transformer; the reactance coils L1 of the magnetic saturation reactors are connected in series with the primary coils L3 of the current transformers; the remaining terminals of the reactance coils L1 are taken as a phase A input terminal, a phase B input terminal and a phase C input terminal of the device; the remaining terminals of the primary coils L3 of the current transformers are taken as a phase A output terminal, a phase B output terminal and a phase C output terminal of the device; the secondary coils L4 of the current transformers are taken as the input of the three-phase bridge type rectifying circuit; the output of the three-phase bridge type rectifying circuit is connected in series with a positive diode and then is connected inseries with the direct current coil L2 of each magnetic saturation reactor so as to form a direct current closed circuit; and the output of the control circuit controls the switch-on or switch-off ofthe three pairs of reverse parallel thyristors respectively.

Description

[0001] technical field [0002] The invention relates to the technical field of power transmission and transformation in power systems, in particular to a three-phase current limiting device and method. Background technique [0003] With the continuous development of the power system and the continuous increase of power generation capacity, the short circuit current caused by the short circuit of the power system is very large. The short circuit current caused by the short circuit in the power system is very harmful to the power system. When a short circuit occurs in the power system, the relay protection device issues a trip command to trip the circuit breaker and cut off the short circuit current. The ability of the circuit breaker to cut off the short-circuit current is limited. When the short-circuit current exceeds the maximum cut-off current value of the circuit breaker, the circuit breaker cannot cut off the short-circuit current. Therefore, reducing the short-circu...

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Problems solved by technology

[0005] Invention patent No.: 2003101235398 "Superconducting Saturated Core Fault Current Limiter" proposes a current limiter that uses the saturation characteristics of the core of a magnetically saturated reactor to form a current limiter. This kind of fault current limiter requires superconducting materials and is expensive. The performance of superconducting materials is unstable, and the maintenance equipment is complicated

Invention patent No.: 2004100802846 "a fault current limiter" also proposes a current limiter that uses the saturation characteristics of the iron core of a magnetically saturated reactor to form a current limiter. The disadvantage of this current limiter is: to provide DC current to the DC coil The circuit is complex; the effect of limiting short-circuit current is limited; only the effect of limiting short-circuit current is not high cost performance, etc.

The three sets of single-phase settings work separately, and the management is more convenient; however, the comprehensive advantages of the joint work of the A, B, and C three-phase systems cannot be brought into play, and some of the mutually supporting resources of the A, B, and C three-phase systems cannot be fully utilized; The limitation of short-circuit current needs to be executed through the trigger command of the controller, and the reliability is not good enough

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