DE2022693A1 - Choke coil arrangement with variable impedance, in particular to limit overcurrents - Google Patents

Description

Patent attorneys 12 6 5

"Ö, Hh _ön2 8, MaM970

^K autinqersir. 8, Tel. 24027ö

3275-70 ELfiCTRICITE DE FRANCE (Service National)

Choke coil arrangement with variable impedance, especially to limit overcurrents.

The invention relates to a choke coil arrangement to limit overcurrents whose impedance is between a first low Yfert and a second high Value is changeable.

The invention relates in particular to the

Applying such an arrangement to the limitation of the in the event of a fault in the high or medium voltage networks for the transport of electrical energy occurring overcurrent.

In the current system, the

occur in the event of an error in the high or low voltage lugs Overcurrents are limited either by increasing the short-circuit voltage of the transformers feeding the harassment, or more often by connecting chokes with fixed impedance in series between the secondary windings of these

00 9-8 47/127 · »- '

- 2 - 'j2'lb-'lü

Transformers and the busbars for distributing the electrical energy.

Such fixed impedance inductors make voltage regulation more difficult, result in losses of electrical energy and require the use of capacitor batteries high capacity to balance the inductive impedance with a capacitive impedance. After all, there is one such arrangement with inductors and capacitors bulky and expensive.

But now such inductors are only

useful and necessary when an error occurs. the Invention therefore proposes a choke coil arrangement, the impedance of which very quickly between a low value and a high value can be changed.

When applying them to the limit

the overcurrents occurring in the event of a fault in an electrical network is the choke coil arrangement according to the invention controlled so that they have a low impedance in normal operation and, as a result of the occurrence of a fault in the network, a has high impedance.

The use of such an arrangement

to limit the overcurrents in the event of faults in the networks the advantage of eliminating the usual capacitor batteries (since the impedance of the choke coil arrangement in normal operation is almost exclusively an ohmic resistance forms), the electrical losses / reduce and the voltage regulation to facilitate.

Incidentally, such an arrangement may

generally used to limit accidental overcurrents v / earth, e.g. to reduce the heating of the transformer windings in the event of such overcurrents, or to enable the switches to be retained, their switching capacity is infolgo the increase in the short-term performance of the lletaes insufficient gov / onien π ind.

Opposite band of the invention lab υ ine au Γ dia

Limitation of overflows applicable drouuelüpulon arrangement with variable impedance, which is characterized by

009847/127 »7 bath original

-3- ^v 3275-70

that they.a choke coil with a magnetic circuit with at least three legs or cores, namely a pair of legs, which carries a first or a second winding, which so are connected in parallel so that their flows add up, and at least one control leg, on which at least one Control winding is wound, and feed means, which normally at least one control winding with a die Feed saturation of the legs of said leg pair causing current, as well as control means, which the saturation of the Lift legs of said pair of legs as a result of an overstroma, has.

When using the inventive

Arrangement to limit the overcurrents occurring in case of a fault in high- A or medium voltage networks, the arrangement formed by the two parallel-connected windings is connected in series between the secondary winding of the transformer and the corresponding bus bars, while the control means controls the saturation as a result of occurrence of an error pick up in the network.

This control leg and functional too

the legs of said pair of legs preferably contain air gaps increasing their magnetic resistance.

According to a first advantageous embodiment, the Magnot circle has three legs, namely one side pair of legs and a middle control leg, on which a control winding is wound, with the feed and control means constituted by an electronic circuit which normally feeds the control winding with a current sufficient to saturate the leg pair and the control winding short-circuits as a result of a control signal, which by monitoring means as a result of the detection an overcurrent, especially in the event of a fault in a network, is produced. .

According to another embodiment,

which often eats more advantageously than the first one has the Magnetic circuit three legs, namely a side pair of legs and the middle Stouornolienkol, which in two ijohonkolhälften is split, of which dio at least one

PO984 · 7/127 ₇ ^a * ° o _meiNAL

2Ü22693

- 4 - 3275-70

carries a winding, which is constantly carried by the food a current causing the saturation of the side pair of legs is fed, while the other leg half is one Control winding carries which of the control means as a result of a control signal with a desaturation of the lateral Leg pair causing current is fed, this jam signal as a result of the detection of an overcurrent, in particular as a result of a mistake in a chase.

The invention is explained below by way of example with reference to the drawing.

1 shows schematically a first embodiment of a choke coil arrangement according to the invention with variable impedance,

Fig. 2 shows the feed and control means of the arrangement of Fig. 1 in more detail.

3 shows schematically a second embodiment of a choke coil arrangement according to the invention with variable impedance.

FIG. 4 shows the feed and control means of the arrangement of FIG. 3 in more detail.

The inventive choke coil arrangement (Fig. 1 and 3) contains a choke coil 1 with a magnetic circuit 2 with at least three legs or cores 11, 12, 13 (Fig. 1) or 11, 12a-12b, 13 (Fig. 3), namely one Leg pair 11, 13 with a first winding 21 and a second winding 23, which are connected in parallel between points A and B so that their fluxes in legs 11 and 13 add up (with windings 21 and 23 depending on the connection of their ends to A and B can be wound in the same direction or in opposite directions) ', and at least one control leg 12 (Fig. 1) or 12a-12b (Fig. 3), on which at least one control winding 22 (Fig. 1) or 22a -22b (Fig ₀ 3) is wound, and feed means 24, which is normally a control winding 22 (Fig. 1) or 22a (Fig. 3) feed with a saturation of the legs 11, 13 of the said pair of legs effecting flow (the strength of which zweckmäss .ig can be regulated by a variable resistor 25 or the like), and Ste uermmittel 26, which the saturation of the legs 11, 13 of the vision

... ν- 0 0 98 477 1277 bad original

- 5 - 3275-70

cancel a pair of poles as a pole of an overcurrent.

In the first embodiment of the Pig.

1, which by the feed and control means in detail pointing pig. 2 is supplemented, the magnetic circuit contains three legs 11, 12, 13, namely two side legs 11, 13 with or without air gaps on which the windings 21, 23 connected in parallel are wound, and one expedient Middle leg 12 containing air gaps 15 on which the control winding 22 is wound.

When the saturation winding 22 of the

Saturation current Is is flowing through, which through the Feed means or the direct current generator 24 generates Ί * ϋ4 and the strength is regulated by the variable resistor 25, this winding in the magnetic circuit 2 generates a (through the arrows f shown) plus Ps, which in the side thighs 11 and 13 have the same direction and sense Has. The plus Pa resulting from the coils 21 and 23 is a Alternating flow and thus in each leg 11, 13, sometimes directed in the direction of arrow f, sometimes in the opposite direction. While of a half-wave are those resulting from the saturation current Plus Ps and the alternating flux Pa in the leg 11 in the same direction and in the leg 13 in opposite directions, during the next Half-wave in the leg 13 in the same direction and in the leg 11 in opposite directions and so on. So they add up at the same time in one leg and subtract in the other.

As a result, owns for the passage

of the alternating current that feeds the windings 21 and 23 in parallel Network 27, one winding (e.g. winding 21) has a low impedance in the positive half-wave, while the other Winding (e.g. winding 23) has a low impedance in the negative half-wave. The impedance of the arrangement connected in parallel is therefore always low.

Generate in the event of an overcurrent in the network

the control means 26 very quickly short-circuit the saturation winding 22 (or its various sections, if subdivided). Since the side legs 11, 13 no longer are saturated, their windings 21, 23 take their high again

D0984 7/1277

- 6 - 3275-70

Nominal impedance, and the arrangement has a high inductive value Impedance, which has the same task as the high inductive impedance of the choke coils used in the prior art met with foster impedance. This high inductive impedance is only effective when an overcurrent occurs, see above that capacitor batteries are no longer required for compensation because the current is only temporarily phase shifted and / or deformed in the event of a fault. Resistance 65 limits the direct current strength during the short circuit.

The ones provided in the control leg 12

Air gaps 15 are intended to reduce the influence of the fluxes emanating from the side legs 11, 13 in the control winding 22, in particular during the transition processes when switching off and switching on the saturation current. Any air gaps in the legs 11 and 13 can enable the regulation of the fluxes generated in the windings 21 and 23 and the Reduce the time to desaturate the legs 11 and 13.

Fig. 2 shows by way of example an embodiment

Approximate form of the means 24 for feeding the winding 22 and the Control means 26 for short-circuiting the winding 22 in the event of a fault in the high or medium voltage network.

Three current transformers 31, 32, 33 represent the

Feillerstrom fixed in the event of an overcurrent in the three-phase network 27 « The fault current is in full wave rectifier cells. 34, 35,

36 rectified and the resistors connected in series

37 and 38 supplied. Between the resistors 37 and 38 39 <ϋθ feeding a potentiometer system with 'a resistor 40 and a potentiometer 41 is at the position removed, the supply voltage of the system is regulated by a Zener diode 42 _s which is caused by a fault current to respond ₉ which by the current transformers 31, 32, 33 and the ratio between the values of the resistors 37 and 38, which fulfill the task of a voltage divider, is determined «,

The potentiometer 41 enables

Determination of the. the emitter 43 of a single layer transistor 44 Voltage applied across resistor 45 * This voltage should be the "peak voltage" of the single-layer transformer in the event of a fault current 44, so that it is conductive

0 098 4 7/127 7 bad original

- 7 - *. '3275-70

power will.

When the transistor 44 due to the occurrence of a through the transformers 31 ,. 32, 33 noted Error current has become conductive, the one at the terminals of the resistor 46 from the DC voltage source 24a generated voltage of, for example, 127 volts, which through the Zener diode 47 and the resistor 48 as well as the resistors 49 and 50 and the potentiometer 51 are set via the resistor 24 to the Control electrode 52 of thyristor 53 is applied.

The thyristor 53 is then in the event of a fault

in turn conductive or permeable and closes the saturation winding 22 short. The discharge current of the winding 22 closes through the diode 55. In fact, the time between the ■ " Occurrence of the fault current and the passage of the discharge current through the diode 55 less than 10 με. The rapidity of this Intervention is sufficient, as it is known that intervention is required in a time which is considerably shorter than the duration of a Half-wave iot to destroy if an overcurrent occurs of the material, especially large transformers.

After removing the saturation current in

the coil 22, the coils 21 and 23 find their high impedance again and limit the short-circuit current, as explained with reference to FIG.

After the interruption of the like by the Iei- become tend thyristor 53 tile forming takes error current, the choke coil 1 again its low impedance by restoring the saturation current in the winding 22 by the following successive. Operations to:

- Supply of a relay 56, which successively closes the contact 57 and opens the Contact 58 causes, wherein the closure of the contact 57 feeds the control electrode 59 of a thyristor 60, which thereby is made conductive or permeable while the opening of the contact 58 interrupts the current flowing through the thyristor 53. In other words, the thyristor 53 v / ird replaced by the thyristor 60?

009847/1277

- 8 - 52Yi ₃ -YO

- De-energization of the relay 56, whereby the

Contact 58 closed and then contact 57 opened vird, the closure of the contact 58 restores the circuit of the thyristor 53, which is again conductive can be if a suitable one as a result of the establishment of a fault in the network 27 by the transformers 31, 32, 33 Voltage is applied to its control electrode 52, while the opening of the contact 57 is the supply of the control electrode 59 of the thyristor 60 interrupts;

- Feeding a relay 61, whereby the

Contact 62 is open and the current in the thyristor 60 is interrupted will;

- De-energization of the relay 61, whereby the

Contact 62 is closed again, whereupon the contacts 57, 58, 62 are in their Pig. 2 shown original Position so that the saturation winding 22 is normally fed from the direct current source 24, which is through the Secondary winding 63 of a voltage converter connected to the network and rectifier diodes 64 are formed with a shunted stabilization capacitor 71 »

The V / iderat and 65 (also shown in Pig. 1) limit the direct current during the short circuit the saturation winding 22.

In Pig. 2 are resistors 66, 67,

68, which with the Zener diode 69 determine the voltage applied to the control electrode 59 of the thyristor 60, the corresponding current intensity being limited by the resistor 70 ^:

In Pig. 3 and 4, a second embodiment is shown, which is often more advantageous than that first is. Pig. 3 shows the entire arrangement, which like the embodiment of the Pig. 1 has a pair of side legs 11, 13, two windings 21 and 23 are wound on polygons, which parallel between the points A and B in the network 27 so are connected in series so that the pluses Pa in the legs 11 and 13 add up.

The main difference between the versions of the Pig 1 and 3 is that the

009847/1277

BATH ORIGINAL

2Ü22693

- 9 - 3275-70

Magnetic circuit 2 of the choke coil 1 is no longer a simple one i-middle limb 12 on v / eist, but two middle limb halves 12a, 12b, which expediently air gaps 15a and 15b included, wherein a winding 22a, 22b is wound onto the leg halves 12a and 12b, respectively, the winding 22a is continuously fed with a saturation current Is from a direct current source 24, while the winding 22b from a DC power source 24a under the control of the means

26 can be fed with a desaturation of the legs 11 and 13 causing current.

Pig. 3 shows the alternating flow Pa, the direction of which changes in each half cycle of the alternating current in the network

27 changes the saturation flow directed in the two legs 11 and 13 in a certain sense, namely that of the arrow f Ps, and the desaturation flow Pd, which in each leg 11, 13 to the saturation flow Ps, i.e. to the arrow f »is opposite to one another.

During normal work is the

Desaturation current Id does not exist, so only the plus Ps occurs in addition to the alternating flow Pa. In normal operation, the conditions are the same as in the embodiment of the Pig. 1 .

When an overcurrent occurs as a result

In the event of an error, the current Id is supplied by the control means 26 from the current source 24a. This stream Id can be a Generate plus Pd, whichever has the same value as the plus Ps has and makes this to zero. You are then in the same position as in the embodiment of the Pig. 1 after the Occurrence of a fault, with no constant flow in the legs 11, 13 being present. Such an approach offers how Incidentally, the first embodiment, the disadvantage, a certain To require duration for the desaturation of the legs 11, 13, a 'not negligible · time constant occurring. It is therefore more expedient to apply a current Id for a short time, which suddenly generates a desaturation flow Pd, whose absolute value is greater than that of the plus Ps, so that the desaturation occurs faster. For this purpose, the winding 22b is fed with a voltage which is higher than that of the

00984771277 ^BA °

2022633

- 10 - 3275-70

Winding 22a is applied, v / o when it is assumed that the two windings and the leg halves 12a, 12b which they are wound up are identical. This additional voltage can be stored in a capacitor, for example Energy received from / to earth, so that after the discharge of the same, the current Id has the same strength as the Current Is, so that the flux Fd is equal to and opposite to the absolute value after the flux Ps. After a short one A constant field of zero is therefore present in the legs 11 and 13 at a faster pace.

It should be noted that in the embodiment of FIG. 3, the air gaps 15a, 15b are enlarged the magnetic resistance of the two leg halves 12a, 12b that of the winding 22a in the leg half 12b and vice versa that of the winding 22b in the leg half 12a to reduce the generated flux to a negligible value.

In a variant of the embodiment of FIG. 3, a single center leg can be provided on which the saturation winding 22a and the desaturation winding 22b are wound, but a considerable electromotive force would be induced in the saturation winding 22a if the desaturation current Id is sent through the desaturation winding 22b becomes, which would be unfavorable. The embodiment of FIG. 3 with two windings 22a, 22b wound onto two separate legs 12a, 12b is therefore to be preferred. _> ■

Indeed, the two legs are

12a, 12b only the two leg halves of a split middle leg. If one would use that is actually four separate legs, ie, two S _e itenschenkel 11, 13, as shown, and two directly emanating from the frame of the magnetic circuit 2 legs 12a, 12b, would the yokes between the center legs of the sum of the saturation flux and 'do3 Would be exposed to desaturation flow and the recovery impedance would be decreased.

Hereinafter, the E, referring to Fig. 4 _r generation of Entsättigungsstroma Id described.

009847/1277

BATH

■ _ 11 - '■ ·.' 3275-70

Fig. 4 initially contains a first

(above the dashed line X-X) part, which with the part of the pig (above the line Y-Y). 2 identical is, with the exception of (in Fig. 2) between the resistor 48 and your resistor 66 existing connection.

So this first part contains three

Current transformers 31 »32, 33, their primary windings in the network 27 switched on sand, three rectifier cells 34, 35, 36, a voltage divider 37, 58 with extraction terminal 39 »one Zener diode 42 and resistors 40, 45, 46, 48, 49 and 50, one of which is used to regulate the voltage applied to the emitter 43 of a single-layer transistor 44 and the other to determine the current which this transistor measures when it is made conductive, the endgül ™ term control by potentiometer 41 and 51 takes place. This A part common to FIGS. 2 and 4 also contains a Zener diode 47 to regulate the voltage applied to the transistor 44 and the resistor 54 to limit the Stroais, which as a result the occurrence of a fault or an overcurrent in the network 27 to the control electrode 82 of a thyristor 81 is created, which in the second (under the line X-X the circuit of FIG. 4) part is included.

Another is found in Fig. 4

Arrangement of Fig. 2 again, specifically the one through the secondary winding 63 and the diodes 64 with the stabilizing capacitor 71 formed direct current feed 24.

The actual control means 26 contain

the thyristor 81, the control electrode 82 of which receives the control signal which is received by the single-layer transiotor becoming conductive 44 is generated as a result of a defect. The thyristor 81 becomes conductive about 10 μ3 after a fault is detected odor permeable. When the thyristor 81 becomes conductive, receives the desaturation winding 22b not only the voltage across the terminals of the capacitor 71, i.e. that across the saturation winding 22a across the resistor 83 applied voltage, but also the discharge voltage of a previously by the power source 24 over capacitor 84 charged across resistor 85.

As a result of the discharge of the capacitor

00984771277

2Ü22693

- 12 - 3275-70

the desaturation current Id is stronger than the saturation current Is. After the transient state, the resistor 85 normally limits the desaturation current Id such that it corresponds to the Absolute value after is equal to the saturation current Is (the value of the resistor 83 is therefore equal to the value of the resistor 85 plus the very low resistance of thyristor 81, assuming windings 22a, 22b are the same). At the moment of the discharge of the capacitor 84, which is actually formed by a capacitor bank, the capacitor plays Resistor 85 no longer matters, and the desaturation current Id is sufficient to generate a desaturation flux which the absolute value is sufficiently larger than the saturation flux to exclude all remanent phenomena

The capacitor 84 thus enables the

Restoration of the significant impedance of the coil 1 in one Time which is shorter than that in the embodiment the pig. 1 by short-circuiting the single winding 22 or for desaturation in the event of a port case of the capacitor 84 in the circuit, the pig. 4 is obtained.

The one required for desaturation

Time can be obtained by changing the ratio between the value of the voltage when the winding 22b is fed by the capacitor 84 and that at the terminals of this winding after the discharge of the capacitor 84, i.e. during normal operation Voltage, or by changing the capacitance of the capacitor 84 can be changed. Palla the value of the current supplied to the saturation winding must be limited, can with the Winding 22b electrically a resistor for discharging the capacitor 84 can be connected in parallel.

Finally, the Mohrfach switch 86 enables the power to be interrupted in both of them at the same time Windings 22a and 22b at the end of the period following the occurrence of a fault or overcurrent. The opening of this Switch causes thyristor 81 to go out. After this extinction, only the multiple switch 86 needs to be closed again to be grounded to the starting point shown in the drawing to return, which allows a new intervention in the event of a new error.

^ _nnn , “ BAD ORIGINAL

009847/1277

- 13 - 3275-70

The diode 87 fulfills the same task

like diode 55 of Fig. 2, i.e. it allows flow the discharge current of the winding 22b,

The reactor arrangement according to the invention with variable impedance; to limit overcurrents has numerous advantages over the known choke coil arrangements, in particular the following:

First of all, their impedance is between one

first small value and a second high value? fast changeable (during a time of, for example, of the order of 10 με).

When applying them to the limit

in the event of a failure in networks for the transport of electrical Energy overcurrents, it enables the omission of the usual capacitor batteries and thus a reduction the costs and space requirements,

In the same application, it enables

reducing electrical energy losses and facilitating the voltage regulation. .

The invention can of course be modified

will. In particular, other circuits than those shown in Pig, 2 and 4 for producing the feed and Control means as well as means other than those described above for detecting an overcurrent can be provided.

0098A771277

Claims (1)

- 14 - 3275-70 Claims 1 A choke coil arrangement with variable impedance to limit overcurrents, characterized by a choke coil (1) with a magnetic circuit (2) with at least three legs or cores (11, 12, 13), namely a pair of legs (11, 13), which has a first Winding (21) or a second winding (23), which are connected in parallel in such a way that their fluxes add up, and at least one control leg (12) on which at least one control winding (22) is wound, as well as feed means (24 ), which normally has at least one control winding with a srseisen the saturation of the legs (11, 13) of said leg.
couple it effectynmir ^ TreTrelTrnrtnrgrl (26), which cancel the saturation of the legs of the leg pair mentioned as a result of an overcurrent, 2.) Arrangement according to claim 1, characterized characterized in that the one or more control legs (12-12a, 12b) their magnetic resistance increasing air gap (15 - 15a, 15b) included. 3 «) arrangement according to claim 1 or 2, characterized in that the legs (11, 13) of said Pair of legs their magnetic. Increasing resistance have air gap θ. 4 ») Arrangement according to one of claims 1 to 3, characterized in that the magnetic circuit (2) has three legs (11, 12, 13), namely a pair of sides « schenkein (11, 13) and a middle control leg (12), on which a control winding (22) is wound, v / obei the supply and control means (24 and 26) by an electronic Circuit are formed, which normally the control winding (22) with one for the saturation of the leg pair (11, 13) feeds sufficient current and short-circuiting this control winding (22) as a result of a control signal can, which by monitoring means as a result of the detection of an overcurrent, in particular on the occasion of an error in a network. 5 ») Arrangement according to one of the claims 00984771277 - 15 - 3275-70 1 to 3, characterized in that the magnetic circuit (2) has three legs (11, 12, 13), namely a pair of Side thighs (11, 13) and a middle control leg, which is split into two leg halves (12a, 12b), one of which has at least one winding (22a), which continuously fed by the feed means (24) with a current causing the saturation of the pair of side legs is, while the other carries a control winding (22b), which from the control means (26) as a result of a control signal is fed with a desaturation of the pair of side legs (11, 13) causing current, wherein the control signal as a result of the detection of an overcurrent, ^ in particular on the occasion of an error in a Ifetz will. 6 ») arrangement according to claim 4, characterized characterized in that the electronic circuit forming the supply and control means (24 or 26) comprises a first normally non-conductive thyristor (53), the control electrode (52) of which receives an error signal as a result of the detection of an error by the monitoring means, this thyristor in "series with a first switch (58) shunted to the control winding (22), a second thyristor (60), which is also in series with a second switch (62) shunted to this winding (22), the control electrode (59) of said second thyristor (60) the third over a Λ switch (57) is connected to a voltage source, contains a likewise to this winding (22) parallel-connected diode (55) and a DC power source (24a) connecting the winding ( 22) feeds with the saturation current, with means (56) are provided, which successively after the ignition of the first thyristor (53) due to an error, the closure of the third switch (57) and the opening of the first switch (53), then the opening of the third switch (57) and the closing of the first switch (58) and then cause the opening of the second switch (62) and finally the closing of the second switch « 7t) arrangement according to claim 5, characterized in that the feed and control means a Thy ~ 0 09847/1277 ^ßAD - 16 - 3275-70 ristor (81, Pig, 4), the control electrode (82) of which sends an error signal as a result of a fault in the network receives, this thyristor being connected in series with the control winding (22b), one parallel to this control winding switched diode (87), at least one capacitor (84) shunted to the control source, one the saturation winding (22a) and the control winding (22b) parallel feeding direct current source (24), to which the capacitor (84) is connected in parallel, and contain a multiple switch (86) which enables the simultaneous disconnection of the saturation winding (22a) from the direct current source (24) and the control winding (22b) and the one connected in parallel to it Diode (87) from this DC power source and the capacitor (84) allowed. 8.) Arrangement according to claim 6 or 7, characterized in that the error signal is in a circuit is generated, which three current transformers (31, 32, 33), whose primary windings are connected to the three lines of the three-phase network are, three each the secondary current of one of the transformers (31, 32, 33) rectifying rectifier cells (34, 35, 36), one the sum of the output currents of the three rectifier cells eiujjfangenden voltage divider (38, 39), a potentiometer arrangement (40, 41), which from the output of the voltage divider as a result of the occurrence of a fault in the three-phase network derives a voltage, and contains a single-layer transistor (44), the control electrode (43) of which the last-mentioned voltage receives, which is set so that the single-layer transistor becomes conductive as a result of a fault in the network, this single-layer transistor in a voltage divider arrangement (46, 49, 50, 51) is switched on, which generates a signal, of which a part is removed to form the error signal will. BATH ORIGINAL 984771277