CN101022217A - Fault current limiter DC control system - Google Patents

Abstract

This invention relates to a DC contol system of a fault limiter characterizing in including: a magnetic energy releasing loop, a quick switch IGBT1, an excitation resuming loop, a constant loop and a quick switch IGBT2, in which, the magnetic releasing loop solves the magnetic energy releasing time by clamping of a piezo-resistor, absorbing energy by large capacitor C1 and a controllable high voltage supply, excitation resuming circuit provides energy of resumed excitation by the conduction of quick switch 2, and the time is adjusted by the voltage source, the constant loop maintains magnetic flux at normal state. This invention uses a single-chip processor with a communication interface with a PC to realize three topical operation states automatically: stable operation of the current limiter, the limit state and superpositioned gate.

Description

Fault current limiter DC control system

Technical field

The invention belongs to saturable core type feeder line fault current limiter DC control technology field.

Background technology

In recent years, the electric power system capacity increases year by year, and the grid short circuit electric current also increases thereupon, has become the key factor of restriction operation of power networks and development at present.Therefore, restriction Power System Shortcuts electric current has become one problem to be solved.Traditional saturable core type power circuit current limiter DC control technology is only to be to use piezo-resistance to absorb energy, make the magnetic field in the iron core withdraw from the magnetic saturation state, and this control system speed is slow, and maintenance capacity is big, the cost height.

Summary of the invention

The control system that the purpose of this invention is to provide a full automatic saturable core type feeder line fault flow restricter.

Saturated core type feeder line fault flow restricter such as is installed between transformer station outlet, bus interconnection at the position, is used for limiting the short-circuit current of electrical network.When electrical network normally moved, flow restricter was very little to the influence on system operation of electrical network; When electrical network was short-circuited fault, it is big that the flow restricter impedance becomes, and short circuit current is restricted to a satisfied back level circuit breaker disconnects desired levels of current; The electrical network reclosing also needs the cooperation of flow restricter.The realization of these functions of flow restricter all needs the current limiter DC control loop to make correspondingly action in all cases.

Be the electrical block diagram of single-phase flow restricter shown in Fig. 1, flow restricter comprises AC Windings, iron core, direct current winding and DC control circuit, should comprise again in the DC control circuit that dc constant current power supply, high-speed switch and magnetic energy discharge function elements such as loop.

The operating state of flow restricter can be summed up as three typical states:

The flow restricter steady operation;

Limited current state;

The reclosing state;

Corresponding to these three states, DC control circuit must have correspondingly action.

Flow restricter moves under stable situation for a long time, and switch is in closure state in the DC control circuit at this moment, and the exciting current that dc constant current power supply provides is biased to degree of depth saturated mode with iron core, and AC Windings presents little impedance.

Electrical network is short-circuited after the fault, after the control system of flow restricter detects fault and takes place, sends signal to DC control circuit, and the high-speed switch in the DC control circuit disconnects fast, and want rapidly operate time.Stored a large amount of magnetic energy in the direct current winding, the moment that disconnects at switch can produce bigger cutoff high, magnetic energy in the control loop discharges the loop and the magnetic energy in the direct current winding can be absorbed rapidly, and the direct current winding voltage is clamped down on level in safety, guarantees that DC loop disconnects rapidly fully.At this moment iron core withdraws from saturatedly, and AC Windings presents big impedance, has limited the short-circuit current of electrical network, and a back level circuit breaker can disconnect safely.

After postponing a period of time, the circuit breaker reclosing in the electrical network.For satisfying before the circuit breaker reclosing, the AC Windings of flow restricter presents little impedance, so before the circuit breaker reclosing, dc constant current power supply is biased to degree of depth saturated mode with the flow restricter iron core, thus require the time of magnetizing of direct current winding must be controlled at circuit breaker reclosing time-delay during this period of time within.

The breaker safe reclosing.If fault is eliminated in the electrical network, electrical network and flow restricter enter steady operation, otherwise repeat above-mentioned course of action, eliminate fully up to fault

The invention is characterized in and contain: direct current winding inductance L1, magnetic energy discharge loop, high-speed switch IGBT1, excitation recovery loop and constant current loop, wherein:

Excitation is recovered the loop, comprises:

Piezo-resistance R0, its clamping voltage are 12KV, this piezo-resistance R0 direct current winding inductance L) parallel connection;

First series arm is in series with big capacitor C 1 by diode D1, C1=500 μ F/12KV, and this first series arm is in parallel with piezo-resistance R0,

Resistance R 2 plays the slow release action of energy, and is in parallel with big capacitor C 1;

Second series arm is in series successively by controllable high-voltage source V1, diode D2, resistance R 1, and the negative electrode of diode D2 links to each other with the negative pole of this controllable high-voltage source V1, V1=0～10KV, and this second series circuit is in parallel with big capacitor C 1;

Excitation discharges the loop, comprises:

The 3rd series arm, high-speed switch IGBT2 by voltage source V 2, resistance R 3,3300V/500A in controlled is in series successively, and resistance R 3 meets this controlled middle voltage source V2 positive pole, the collector electrode connecting resistance R3 of this high-speed switch IGBT2, and emitter meets direct current winding inductance L1

Capacitor C 2 is 32000 μ F/1600V, two ends respectively with this controlled in the negative pole of voltage source V 2, link to each other with the collector electrode of this high-speed switch IGBT2,

High-speed switch IBGT1,15KV/500A, emitter links to each other with the negative pole of this controlled middle voltage source V 2, and the current collection level connects the positive pole of this diode D1,

Constant current loop comprises:

Constant-current source I1,0～5V/500A, the emitter of one termination high-speed switch IGBT1, and other end forward links to each other with iron core direct current winding inductance L1 after meeting an isolating diode D3,

Forward diode in series D7, D6, D5 and D4 successively, the negative pole of this diode D4 connects the emitter of high-speed switch IGBT1, and the positive pole of diode D7 connects the positive pole of diode D3;

After high-speed switch disconnected, magnetic energy discharged the loop to selected magnetic energy and discharges;

Constant-current source I1 keeps magnetic flux after being used to magnetize, and at back control diode D3 and the direct current winding inductance L1 of normally magnetizing, the pressure drop of high-speed switch IGBT1 is less than diode D4, D5, D6, D7 pressure drop sum; Under the magnetic energy absorption and the state that magnetizes, continuous current is by diode in series D4, D5, D6, D7 afterflow; Magnetizing the later stage in stage, when the electric current of direct current winding inductance L1 during near the constant-current source electric current, high-speed switch IGBT2 disconnects, and the electric current of direct current winding inductance L1 is by the afterflow of constant-current source electric current.

Described DC control system has with the single-chip microcomputer of host computer communication interface by one to be controlled, this single-chip microcomputer is provided with: electric current, the voltage of direct current winding inductance L1, the voltage of two capacitor C 1, C2, the sampling input of constant-current source I1 output current, this single-chip microcomputer also is provided with: two high-speed switch IGBT1, IGBT2, controllable high-voltage power supply V1, the control output of controlled middle control signal voltage source V 2 and constant-current source I1.

The present invention can carry out Automatic Control under unit control.

Description of drawings:

The single-phase current limiter circuit structural representation of Fig. 1, three correspondingly have six iron cores, and L1 is the direct current winding.

Fig. 2 circuit theory diagrams of the present invention.

Embodiment

Now major part of the present invention is described below:

1, magnetic energy discharges the loop:

The loop that D1, C1, R2, V1, D2, R1, R0 form as shown in schematic diagram

V1: 0～10kV is adjustable for the high-tension electricity potential source, power 1kW (0.1A)

C1, R1, D2:V1 charge to C1 by R1, D2, VC1=V1 during normal steady state condition

R2: energy slowly discharges resistance

R0: piezo-resistance, clamping voltage 12kV

C1 selects large bulk capacitance, and V1 transfers to 10kV, then VC1=10kV.After IGBT1 disconnected, iL1 charged to C1, because C1 is bigger, VC1 rises slowly, and energy changes the energy storage of C1 into by the magnetic energy of L1, and was slowly discharged by R1.

When magnetic energy discharged, the L1 two ends added-the clamping voltage VL1 of 10kV, because So $\mathrm{dB}=\frac{{\mathrm{<figure-callout\; id="1"\; label="V\; L"\; filenames="A20071006324600091.png"\; state="\{\{state\}\}">V</figure-callout>}}_L}{\mathrm{NS}}\mathrm{dt},$ Magnetic flux density among the L1 descends fast, plays the effect that magnetic energy discharges.

Prompt drop is low as quickly as possible with the B among the L1 in 5ms for system requirements, so that it is saturated deeply that L1 is withdrawed from, makes magnetic circuit system produce current limitation effect, if VL1=-10kV, and since N=600, S=0.9m2, in Δ t=5ms, $\mathrm{\&Delta;B}={\&Integral;}_0^{5\&times;{10}^{-3}}\frac{-10\&times;{10}^3}{600\&times;0.9}\mathrm{dt}=-0.092T.$ If this Δ B1 can not make magnetic circuit system produce desirable current limitation effect, increase the absolute value of Δ B, if from following formula, can improve as can be seen | and VL1| or increase Δ t Δ t do not allow to increase, and have only raising | VL1|.

The selection of C1:

Select C1=500uF/12kV, after one time magnetic energy absorbed, VC1 became VC1 ' by 10kV, has $\frac{1}{2}{C}_1(V_{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="A20071006324600091.png"\; state="\{\{state\}\}">C</figure-callout>}1}^{\&prime;2}-{\mathrm{<figure-callout\; id="1"\; label="V\; C"\; filenames="A20071006324600091.png"\; state="\{\{state\}\}">V</figure-callout>}}_C^1)=5000J,$ VC1 '=10954V then, VC1 increases 954V, after magnetic energy absorbs for the second time, VC1 '=11832V.

2, excitation is recovered the loop:

The loop that V2, R3, C2, IGBT2 form as shown in schematic diagram

V2: middle piezoelectricity potential source, 0～1600V is adjustable, power 1kW (0.625A)

C2, R3:V2 charge to C2 by R3, VC2=V2 during normal steady state condition

When magnetic energy recovers, IGBT1, IGBT2 conducting, VC2 is added to the L1 two ends by IGBT2, VL1=VC2＞0, according to $\mathrm{dB}=\frac{{\mathrm{<figure-callout\; id="1"\; label="V\; L"\; filenames="A20071006324600091.png"\; state="\{\{state\}\}">V</figure-callout>}}_L}{\mathrm{NS}}\mathrm{dt},$ Magnetic flux density among the L1 increases, when V2=1350V, and at Δ t=0.8 in second, $\mathrm{\&Delta;B}={\&Integral;}_0^{0.8}\frac{1350}{600\&times;0.9}\mathrm{dt}=2T,$ Therefore, as long as V2 〉=1350 just can be satisfied in the time that requires excitation is recovered.

Get C2=32000uF/1600V, after one time excitation was recovered, VC2 reduced to VC2 ' by 1600V, then has $\frac{1}{2}{C}_2(V_{C2}^2-V_{C2}^{\&prime;2})=5000J,$ VC2 '=1500V then, by that analogy, behind the reclosing 2 times, $\frac{1}{2}{C}_2(V_{C2}^2-V_{C2}^{\&prime;2})=2\&times;5000J,$ VC2 '=1390＞1350V, this voltage can satisfy the demand of No. the 3rd reclosing of system.

3, constant-current source: I1 is that 0～500A is adjustable, maximum output voltage 5V

The effect of constant-current source is the keeping of magnetic flux afterwards of magnetizing, and after normally magnetizing, the pressure drop of control D3, L1, IGBT1 is less than the pressure drop of D4, D5, D6, D7, and then iI1 flows by D3, L1, IGBT1.Magnetic energy absorbs and when magnetizing state, iI1 is all by D4, D5, D6, D7 afterflow.In the latter stage in the stage of magnetizing, when system detects iL1 near iI1, IGBT2 is disconnected, iL1 changes by the iI1 afterflow.

4, DC control unit

It is the Single-chip Controlling of core that control unit adopts the TMS320C240DSP of TI company, has the communication interface with host computer, receives instructions such as magnetic energy from host computer absorbs, magnetizes, and gives host computer state feedback.

Control unit is sampled to analog quantitys such as iL1, uL1, VC1, VC2, II1, and the turn-on and turn-off of IGBT1, IGBT2 are controlled, and output voltage, the electric current of V1, V2, I1 are set.

5, main circuit main element parameter list

Element number	Attribute	Parameter
			R0	Piezo-resistance	20kA/12kV
C1	Electric capacity	500uF/12kV
			V1	DC high-voltage power supply	10kV/0.1A
V2	Voltage source in the direct current	1600V/0.625A
			I1	Constant-current source	0~5V/500A
C2	Electric capacity	32000uF/1600V
			IGBT1	IGBT (series connection)	15kV/500A
IGBT2	IGBT	3300V/500A

Claims (2)

1. fault current limiter DC control system is characterized in that, contains: direct current winding inductance (L1), magnetic energy discharge loop, high-speed switch (IGBT1), excitation recovery loop and constant current loop, wherein:

Excitation is recovered the loop, comprises:

Piezo-resistance (R0), its clamping voltage are 12KV, and this piezo-resistance (R0) is in parallel with direct current winding inductance (L1);

First series arm is in series by diode (D1) and big electric capacity (C1), (C1)=500 μ F/12KV, and this first series arm is in parallel with piezo-resistance (R0),

Resistance (R2) plays the slow release action of energy, and (C1) is in parallel with big electric capacity;

Second series arm, be in series successively by controllable high-voltage source (V1), diode (D2), resistance (R1), the negative electrode of diode (D2) links to each other with the negative pole in this controllable high-voltage source (V1), (V1)=0～10KV, this second series circuit is in parallel with big electric capacity (C1);

Excitation discharges the loop, comprises:

The 3rd series arm, high-speed switch (IGBT2) by voltage source (V2), resistance (R3), 3300V/500A in controlled is in series successively, resistance (R3) connects this controlled middle voltage source (V2) positive pole, the collector electrode connecting resistance (R3) of this high-speed switch (IGBT2), and emitter connects direct current winding inductance (L1)

Electric capacity (C2) is 32000 μ F/1600V, two ends respectively with this controlled in the negative pole of voltage source (V2), link to each other with the collector electrode of this high-speed switch (IGBT2),

High-speed switch (IBGT1), 15KV/500A, emitter links to each other with the negative pole of this controlled middle voltage source (V2), and the current collection level connects the positive pole of this diode (D1),

Constant current loop comprises:

Constant-current source (I1), 0～5V/500A, the emitter of one termination high-speed switch (IGBT1), and other end forward links to each other with iron core direct current winding inductance (L1) after connecing an isolating diode (D3),

Forward diode in series (D7), (D6), (D5) and (D4) successively, the negative pole of this diode (D4) connects the emitter of high-speed switch (IGBT1), and the positive pole of diode (D7) connects the positive pole of diode (D3);

After high-speed switch disconnected, magnetic energy discharged the loop to selected magnetic energy and discharges;

Keep magnetic flux after constant-current source (I1) is used to magnetize, at back control diode (D3) and the direct current winding inductance (L1) of normally magnetizing, the pressure drop of high-speed switch (IGBT1) is less than diode (D4), (D5), (D6), (D7) pressure drop sum; Under the magnetic energy absorption and the state that magnetizes, continuous current is by diode in series (D4), (D5), (D6), (D7) afterflow; Magnetizing the later stage in stage, when the electric current of direct current winding inductance (L1) during near the constant-current source electric current, high-speed switch (IGBT2) disconnects, and the electric current of direct current winding inductance (L1) is by the afterflow of constant-current source electric current.

2. fault current limiter DC control system according to claim 1, it is characterized in that, described DC control system has with the single-chip microcomputer of host computer communication interface by one to be controlled, this single-chip microcomputer is provided with: electric current, the voltage of direct current winding inductance (L1), the voltage of two electric capacity (C1), (C2), the sampling input of constant-current source (I1) output current, this single-chip microcomputer also is provided with: two high-speed switches (IGBT1), (IGBT2), controllable high-voltage power supply (V1), the control output of controlled middle control signal voltage source (V2) and constant-current source (I1).

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