CN104410057A - Short-circuit limiter for power system - Google Patents

Abstract

The invention discloses a short-circuit limiter for a power system. The short-circuit limiter for the power system comprises a transformer T, a capacitor C1 connected with a primary coil of the transformer T in parallel, an inductor L1 connected with the capacitor C1 in series, a plurality of first branch circuits connected with a secondary coil of the transformer T in parallel, and a controller used for controlling the conduction of the first branch circuits; the first branch circuit comprises a controllable switch SCR1, a resistor R1 and an inductor L2 which are mutually connected in series, and the controller is connected with the controllable switch SCR1. The short-circuit limiter presents low impedance when a power grid operates normally, presents high impedance when short circuit occurs to the power grid, and presents low impedance when the power grid recovers from the failure of short circuit to normal operation, and the automatic resetting is realized.

Description

A kind of Power System Shortcuts demand limiter

Technical field

The present invention relates to a kind of electric power system power transmission and distribution technical field, be specially a kind of Power System Shortcuts demand limiter.

Background technology

Along with the expansion of electric power system scale, the electric power system short circuit current caused that is short-circuited also increases thereupon, and the harm of Power System Shortcuts electric current to electric power system is very large, therefore needs short circuit current to be reduced to controlled, safe level; Desirable short circuit current limiter should have no resistance or Low ESR when electrical network normally runs, electrical network presents high impedance when being short-circuited, the response time is rapid, reliability is high and automatically reset feature.Shown in figure 1, the short circuit current limiter that in prior art, electric power system uses is formed primarily of inductance L, electric capacity C, resistance R and controllable silicon SCR; When electrical network normally runs, inductance L and electric capacity C are in resonance condition, equiva lent impedance is zero, and the pressure drop of short circuit current limiter two ends is minimum, after electrical network is short-circuited, the voltage rise of electric capacity C, now controlled silicon conducting, the condition of resonance of inductance L and electric capacity C is destroyed, and is equivalent to electric capacity C and is shorted, such short circuit current limiter will present the perception of inductance L, thus limiting short-circuit current; There are the following problems for this short circuit current limiter: because controllable silicon SCR subjects the electric current that will discharge when high voltage that electric capacity C produces and electric capacity C are shorted, therefore reliability is not high, directly affects the security performance of electric power system.

Summary of the invention

The present invention is directed to the proposition of above problem, and develop a kind of Power System Shortcuts demand limiter.

Technological means of the present invention is as follows:

A kind of Power System Shortcuts demand limiter, comprising: transformer T, the electric capacity C1 be in parallel with the primary coil of transformer T, the inductance L 1 of mutually connecting with electric capacity C1, multiple be in parallel with the secondary coil of transformer T the first branch road, for controlling the controller that the first branch road is connected; Described first branch road comprises controllable switch S CR1, resistance R1 and the inductance L 2 of series connection mutually; Described controller connects described controllable switch S CR1;

Further, the induction reactance that multiple first branch road parallel with one another has equals induction reactance that inductance L 1 the has no-load voltage ratio divided by described transformer T;

Further, described controllable switch S CR1 is controllable silicon; Described controller exports triggering signal to described controllable switch S CR1 when electric power system is short-circuited fault;

Further:

When electric power system normally works, the secondary coil open circuit of described transformer T, described inductance C1 and electric capacity C1 forms series resonant circuit;

When electric power system is short-circuited fault, described controller triggers described controllable switch S CR1 conducting, after the induction reactance that multiple first branch road parallel with one another has is multiplied by the no-load voltage ratio of described transformer T, equivalence becomes inductive reactive element, and this inductive reactive element and electric capacity C1 form antiresonant circuit;

When electric power system by short trouble return to normally work time, described controllable switch S CR1 turns off due to current over-zero, and described inductance C1 and electric capacity C1 reconstitutes series resonant circuit.

Owing to have employed technique scheme, a kind of Power System Shortcuts demand limiter provided by the invention, can realize presenting Low ESR when electrical network normally runs, high impedance is presented when electrical network is short-circuited, Low ESR is presented when electrical network returns to normal operation by short trouble, realization automatically resets, solving short circuit current limiter of the prior art due to controllable silicon SCR subjects the electric current that will discharge when high voltage that electric capacity C produces and electric capacity C are shorted, therefore the problem that reliability is not high, response time of the present invention is rapid, reliability is high, be beneficial to the security performance ensureing electric power system.

Accompanying drawing explanation

Fig. 1 is the electrical block diagram of the short circuit current limiter that in prior art, electric power system uses;

Fig. 2 is the electrical block diagram of short circuit current limiter of the present invention.

Embodiment

A kind of Power System Shortcuts demand limiter as shown in Figure 2, comprising: transformer T, the electric capacity C1 be in parallel with the primary coil of transformer T, the inductance L 1 of mutually connecting with electric capacity C1, multiple be in parallel with the secondary coil of transformer T the first branch road, for controlling the controller that the first branch road is connected; Described first branch road comprises controllable switch S CR1, resistance R1 and the inductance L 2 of series connection mutually; Described controller connects described controllable switch S CR1; Further, the induction reactance that multiple first branch road parallel with one another has equals induction reactance that inductance L 1 the has no-load voltage ratio divided by described transformer T; Further, described controllable switch S CR1 is controllable silicon; Described controller exports triggering signal to described controllable switch S CR1 when electric power system is short-circuited fault; Further: when electric power system normally works, the secondary coil open circuit of described transformer T, described inductance C1 and electric capacity C1 forms series resonant circuit; When electric power system is short-circuited fault, described controller triggers described controllable switch S CR1 conducting, after the induction reactance that multiple first branch road parallel with one another has is multiplied by the no-load voltage ratio of described transformer T, equivalence becomes inductive reactive element, and this inductive reactive element and electric capacity C1 form antiresonant circuit; When electric power system by short trouble return to normally work time, described controllable switch S CR1 turns off due to current over-zero, and described inductance C1 and electric capacity C1 reconstitutes series resonant circuit; The induction reactance of inductance L 1 is equal with the capacitive reactance of electric capacity C1.

Short circuit current limiter of the present invention is when electric power system normally works, controller does not export controllable switch S CR1 triggering signal, controllable switch S CR1 not conducting, transformer T secondary coil is opened a way, short circuit current limiter forms series resonance by inductance L 1 and electric capacity C1, now short circuit current limitation limiter presents Low ESR, and two ends pressure drop is minimum, practical application Time Controller is by detecting short circuit current in real time to judge whether electric power system is short-circuited fault, when electric power system is short-circuited fault, controller exports triggering signal and controls controllable switch S CR1 conducting, now the first branch road is equivalent to resistance R1 and the inductance L 2 of series connection mutually, transformer T is in transformation state, described transformer T has transformation and isolation two effects, through the voltage transformation of transformer T, the voltage in resistance R1 and loop, controllable switch S CR1 place can be in controlled scope as below 2000V, and the major loop at controllable switch S CR1 and inductance L 1 and electric capacity C1 place does not have direct electrical link, be beneficial to raising reliability, after total induction reactance after inductance L 2 parallel connection in each first branch road is multiplied by the no-load voltage ratio of transformer T, equivalence becomes the inductive reactive element of primary side, and form antiresonant circuit with electric capacity C1, now short circuit current limitation limiter presents high impedance, total current in circuit is minimum, and then play the effect of limiting short-circuit current, when electric power system by short trouble return to normally work time, now short circuit current disappear, described controllable switch S CR1 turns off due to current over-zero, and described inductance C1 and electric capacity C1 reconstitutes series resonant circuit, and short circuit current limitation limiter presents Low ESR.Short circuit current limiter provided by the invention can realize presenting Low ESR when electrical network normally runs, high impedance is presented when electrical network is short-circuited, Low ESR is presented when electrical network returns to normal operation by short trouble, realization automatically resets, solving short circuit current limiter of the prior art due to controllable silicon SCR subjects the electric current that will discharge when high voltage that electric capacity C produces and electric capacity C are shorted, therefore the problem that reliability is not high, the response time of the present invention is rapid, reliability is high, be beneficial to the security performance ensureing electric power system.

The above; be only the present invention's preferably embodiment; but protection scope of the present invention is not limited thereto; anyly be familiar with those skilled in the art in the technical scope that the present invention discloses; be equal to according to technical scheme of the present invention and inventive concept thereof and replace or change, all should be encompassed within protection scope of the present invention.

Claims (4)

1. a Power System Shortcuts demand limiter, is characterized in that comprising: transformer T, the electric capacity C1 be in parallel with the primary coil of transformer T, the inductance L 1 of mutually connecting with electric capacity C1, multiple be in parallel with the secondary coil of transformer T the first branch road, for controlling the controller that the first branch road is connected; Described first branch road comprises controllable switch S CR1, resistance R1 and the inductance L 2 of series connection mutually; Described controller connects described controllable switch S CR1.

2. a kind of Power System Shortcuts demand limiter according to claim 1, is characterized in that induction reactance that multiple first branch road parallel with one another has equals induction reactance that inductance L 1 the has no-load voltage ratio divided by described transformer T.

3. a kind of Power System Shortcuts demand limiter according to claim 1, is characterized in that described controllable switch S CR1 is controllable silicon; Described controller exports triggering signal to described controllable switch S CR1 when electric power system is short-circuited fault.

4. a kind of Power System Shortcuts demand limiter according to claim 3, is characterized in that:

When electric power system normally works, the secondary coil open circuit of described transformer T, described inductance C1 and electric capacity C1 forms series resonant circuit;

When electric power system is short-circuited fault, described controller triggers described controllable switch S CR1 conducting, after the induction reactance that multiple first branch road parallel with one another has is multiplied by the no-load voltage ratio of described transformer T, equivalence becomes inductive reactive element, and this inductive reactive element and electric capacity C1 form antiresonant circuit;

When electric power system by short trouble return to normally work time, described controllable switch S CR1 turns off due to current over-zero, and described inductance C1 and electric capacity C1 reconstitutes series resonant circuit.