CN103580013B

CN103580013B - A kind of short circuit current limiter

Info

Publication number: CN103580013B
Application number: CN201310523357.3A
Authority: CN
Inventors: 贾继莹
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-10-30
Filing date: 2013-10-30
Publication date: 2016-03-23
Anticipated expiration: 2033-10-30
Also published as: CN103580013A

Abstract

The invention provides a kind of short circuit current limiter, problem to be solved is: the controllable silicon in LC series resonance-type flow restricter will bear high voltage and big current, causes its reliability to reduce.Main points of the present invention are: at the inductance L two ends parallel equivalent condenser network C ' of LC series resonant circuit, equivalent capacity circuit C ' forms parallel circuits with inductance L; Equivalent capacity circuit is, low-voltage capacitance group circuit is received in the loop of the low-voltage side coil of transformer T, the high-pressure side coil of transformer T is in parallel with inductance L: low-voltage capacitance, resistance and controllable silicon in serial connection form a branch road, and several such branch circuit parallel connections form above-mentioned low-voltage capacitance group circuit; The low-pressure side voltage of single-phase transformer T is below 2000V, and high-pressure side is 10-1000KV.Good effect of the present invention is that reliability improves greatly.

Description

A kind of short circuit current limiter

Technical field

The present invention relates to power transmission and distribution field, to the restriction of short circuit current when specifically electrical network is short-circuited in transmission of electricity process.

Background technology

Short circuit current is a major issue of electric power system.Along with the expansion of electric power system scale, short circuit current also increases thereupon, needs short circuit current to be reduced to controlled, safe level.Desirable short circuit current limiter should have following characteristics: no resistance or Low ESR when electrical network normally runs, present high impedance when electrical network is short-circuited, and the response time is rapid, and reliability is high, automatically resets.

The short circuit current limiter mainly LC series resonance-type flow restricter used in electrical network at present, its induction reactance is equal with capacitive reactance, as Fig. 1, when electrical network normally runs, resonance condition is between LC, equiva lent impedance is zero, the pressure drop of limiter two ends is minimum, after electrical network is short-circuited electric current, the voltage rise of electric capacity C, controllable silicon KP conducting this moment (R1 is that restricted passage silicon controlled shoves), the condition of resonance of inductance L and electric capacity C is destroyed, be equivalent to C be shorted, such circuit will present the perception of L, thus electric current is locked.LC series resonance-type flow restricter in actual applications institute's produced problem is that failure rate is higher, and tracing it to its cause is that controllable silicon will bear high voltage that electric capacity C produces and the big current that electric capacity C will discharge when being shorted.

Summary of the invention

For solving the problems of the technologies described above, the object of this invention is to provide a kind of short circuit current limiter, it is series resonance when circuit is normal, inductance in parallel electric capacity when being short-circuited, thus makes circuit manifest high impedance, limiting short-circuit current.

The object of the present invention is achieved like this: it comprises LC series resonant circuit, it is characterized in that: at the inductance L two ends parallel equivalent condenser network C ' of LC series resonant circuit, equivalent capacity circuit C ' forms parallel circuits with inductance L; Said equivalent capacity circuit is, low-voltage capacitance group circuit is received in the loop of the low-voltage side coil of transformer T, the high-pressure side coil of transformer T is in parallel with inductance L: low-voltage capacitance, resistance and controllable silicon in serial connection form a branch road, and several branch circuit parallel connections identical like this form above-mentioned low-voltage capacitance group circuit; The low-pressure side voltage of said single-phase transformer T is below 2000V, and high-pressure side is 10-1000KV.

When electrical network normally works, the controllable silicon in not conducting low-voltage capacitance group circuit, at this moment transformer T is only equivalent to an infinitely-great inductance of inductance value, does not play a role, now LC series resonant circuit resonance, and its two ends pressure drop is minimum; When there is short circuit current in electrical network, controllable silicon in the controller trigger low-voltage capacitance group circuit separately established, transformer T runs, the total capacitance of low-voltage capacitance group circuit is become C ' by equivalence to high voltage side of transformer by transformer voltage ratio, C ' forms parallel relationship with L, circuit manifests high impedance, limiting short-circuit current; When short circuit current disappears, controllable silicon naturally can turn off after zero crossing, and LC series resonant circuit is in resonance condition, and electrical network normally works.

Compared with prior art, the present invention is owing to employing transformer, and controllable silicon is connected on the low-pressure side of transformer, and is shunted by the branch road of parallel connection by each silicon controlled electric current, and the electric current that each controllable silicon bears and voltage reduce greatly; Secondly electrical network major loop and controllable silicon are kept apart by transformer, make reliability of the present invention greatly improve like this, and with low cost.

Accompanying drawing explanation

The present invention is further illustrated below in conjunction with accompanying drawing.

Fig. 1 is LC series resonance-type flow restricter electrical schematic diagram.

Fig. 2 is electrical schematic diagram of the present invention.

Fig. 3 is the electrical schematic diagram that the present invention is applied in electrical network.

Embodiment

See Fig. 2, at the inductance L two ends parallel equivalent condenser network C ' of LC series resonant circuit, equivalent capacity circuit C ' forms parallel circuits with inductance L; Said equivalent capacity circuit is, low-voltage capacitance group circuit is received in the loop of the low-voltage side coil of transformer T, the high-pressure side coil of transformer T is in parallel with inductance L: low-voltage capacitance C1 ', a resistance R1 and controllable silicon KP1 branch road in series, and 395 identical like this branch circuit parallel connections form above-mentioned low-voltage capacitance group circuit; The low-pressure side voltage of said single-phase transformer T is 385V, and high-pressure side is 10000/1.73V, no-load voltage ratio 15.Because the maximum permission operating current of 10KV distribution is 800A, add the nargin of 20%, if fault current is 1000A; L hollow inductance, 18.4mH, 10KV; C is high-voltage capacitance group, and total capacitance is 551 μ F, 10KV, is placed on insulated platform, and power is 5774 kilovars.The C1 ' of the first branch road is 314 μ F, every phase 395 branch roads, then low-voltage capacitance group circuit total capacitance is 124030 μ F, is 551 μ F through no-load voltage ratio (15 square) conversion of transformer T to high-pressure side, namely equivalent capacity circuit C ' is that 551 μ F(and C are equal), C ' and L parallel resonance.Wherein the resistance of resistance R can be selected, and plays Limited Current.For making numerous R have enough dissipation powers, can resistor rod be made, under water.

See Fig. 3, every phase line of electrical network arranges a present invention, the controller separately established reads the voltage of every phase L and the electric current of every phase, parameter according to setting judges whether the triggering command sending KP1, when short trouble is removed, silicon control zero-cross ends, and circuit clear-cutting forestland normally runs.

KP2 is used to some electric capacity of conducting, controls its conducting quantity, can adjust the capacitance of building-out capacitor.And according to the power factor of each phase, the KP2 of conducting respective numbers, can complete the reactive power compensation of each phase.The combination of conducting KP1 and KP2 can be controlled neatly, adjustment capacitive component and the value of resistive component, and control the characteristic of whole demand limiter, and control program be become be enriched.

Claims

1. a short circuit current limiter, it comprises LC series resonant circuit, it is characterized in that: at the inductance L two ends parallel equivalent condenser network C ' of LC series resonant circuit, equivalent capacity circuit C ' forms parallel circuits with inductance L; Said equivalent capacity circuit C ' is, low-voltage capacitance group circuit is received in the loop of the low-voltage side coil of transformer T, the high-pressure side coil of transformer T is in parallel with inductance L: low-voltage capacitance, resistance and controllable silicon in serial connection form a branch road, and several branch circuit parallel connections identical like this form above-mentioned low-voltage capacitance group circuit; The low-pressure side voltage of said transformer T is below 2000V, and high-pressure side is 10-1000KV.

2. according to a kind of short circuit current limiter according to claim 1, it is characterized in that: said branch road is 395.