High-voltage circuit breaker equipped with a switching current injection device, and method for driving same

Abstract

The invention relates to a high-voltage circuit breaker (3) comprising: - a main conduction branch (31) comprising a driven switch (32); - a switching branch (33) configured to selectively inject a current into the driven switch (32) and comprising an oscillating circuit including at least one inductor and a capacitive circuit (332), and also comprising a selection circuit (333) configured to select the direction of discharge of the capacitive circuit (332); - an activation switch (330) configured to selectively cut off or carry the current in the switching branch (33); - a control circuit (2) configured to identify the direction of the current flowing through the driven switch (32) and configured to drive the selection circuit (333) and the activation switch (330) with a view to selectively initiating the discharge of the capacitive circuit into the driven switch in a direction opposite to the identified direction of the current.

Description

Description Title of the invention: High-voltage circuit breaker equipped with a switching current injection device

[0001] [The invention relates to electrical networks, and in particular to high voltage circuit breakers equipped with a main conduction and breaking branch, and a switching branch intended to assist the breaking of the main branch.

[0002] Circuit breakers are essential components of electrical networks, as they must allow for the isolation of a portion of the electrical network from a fault. Thus, a circuit breaker in operation is in a current-conducting position but must be able to interrupt this current when a fault occurs.

[0003] Interrupting high-voltage direct current is more complex than interrupting alternating current. This is because interrupting an alternating current relies on a zero-crossing of the current to achieve the electrical break, which is not possible with high-voltage direct current.

[0004] Current-injection circuit breakers, as described in document FR2103336, were developed to interrupt direct current. These circuit breakers use a main branch carrying direct current during normal operation and a parallel switching branch. The main branch sometimes includes a vacuum bulb switch configured to selectively maintain or interrupt current flow. The parallel branch includes an oscillating circuit configured to inject current into the main branch to force a zero crossing of the current through the switch when the circuit breaker is interrupted. In this example, the parallel branch includes a pre-charged capacitor.During a fault, a circuit breaker opening command is generated. The current injection by the capacitor creates a zero crossing of the current through the switch, thus interrupting the arc between the switch contacts. The switch must then withstand the resulting voltage to prevent the arc from reignition. Subsequently, the branch of... R012535 PCT Depot Text.docx switching is also cut off, before the residual energy on the network dissipates in a surge protector.

[0005] The current injection device is calibrated with respect to the maximum amplitude of the fault current to which the vacuum bulb can be subjected. However, the direction of the fault current is variable, so the current is initially injected into the main branch either in the same direction or in the opposite direction to the fault current. Therefore, the current injection is calibrated to cause a zero crossing in the main branch either during the first half-period of the current injection oscillation or during the second half-period of the current injection oscillation.

[0006] In certain configurations, the parallel switching branch may consist of several modules connected in series to ensure its voltage resistance. Particularly in this type of configuration, the resistance in the oscillating circuit during an injection is high. Such resistance increases the damping coefficient of the oscillating circuit. To guarantee that the current crosses zero in the main branch, the parallel branch must then be sized to inject a very high amplitude current. Such a sizing of the parallel branch hinders the deployment of such high-voltage circuit breakers due to the associated costs.

[0007] Furthermore, such high-voltage circuit breakers are not suitable for certain operating cycles of high-voltage networks. Indeed, when a fault is identified, the circuit breaker often initially receives a trip request, then is re-energized to test if the fault has cleared, before receiving another trip request if the fault persists. For such operating cycles, the parallel switching branch is not configured to inject new current upon the subsequent trip request.

[0008] Document JP2017004869 describes a current-injection circuit breaker. This injection circuit breaker comprises a main branch with a high-breaking-capacity, pilot-operated mechanical switch and an insulated-state, pilot-operated mechanical switch. The implementation of the sequence R012535 PCT Depot Text.docx Opening the main branch proves to be relatively complex and requires the presence of two controlled mechanical switches connected in series.

[0009] Document EP3089301 describes a current-injection circuit breaker. This current-injection circuit breaker is of the four-pole type. One switching branch has two directions of current injection into a piloted main switch. Current injection in one direction is achieved via a ground connection.

[0010] Document EP2979291 describes a current-injection circuit breaker. This circuit breaker has two switching branches that can be selected to inject current into a main switch controlled according to a respective injection direction.

[0011] The invention aims to resolve one or more of these drawbacks. The invention thus relates to a high-voltage circuit breaker, as defined in attached claim 1.

[0012] The invention also relates to variants of the dependent claims. Those skilled in the art will understand that each of the features of the dependent claims or of the description can be combined independently with the features of an independent claim, without thereby constituting an intermediate generalization.

[0013] The invention further relates to a method for controlling a high-voltage circuit breaker, as defined in the claims.

[0014] Other features and advantages of the invention will become clear from the description given below, by way of example and not limitation, with reference to the accompanying drawings, in which:

[0015] [Fig.1] is a schematic representation of an example embodiment of a switching device including high-voltage circuit breakers according to the invention;

[0016] [Fig.2] is a schematic representation of a circuit breaker illustrated in figure 1;

[0017] [Fig.3] illustrates a principle example of a switching branch of the circuit breaker in Figure 2; R012535 PCT Deposit Text.docx

[0018] [Fig.4] illustrates a first embodiment of an example of implementation of a selection circuit combined with a capacitive circuit;

[0019] [Fig.5], [Fig.6], [Fig.7] and [Fig.8] illustrate different conduction configurations of the components of the selection circuit in Figure 4;

[0020] [Fig.9] illustrates a second embodiment of an example of implementation of a selection circuit combined with a capacitive circuit;

[0021] [Fig.10] illustrates a third embodiment of an example of implementation of a selection circuit combined with a capacitive circuit;

[0022] [Fig.11] illustrates a first embodiment of an example of a switching branch activation switch;

[0023] [Fig.12] illustrates a second embodiment of an example of a switching branch activation switch.

[0024] Fig. 1 illustrates a first example of an implementation of a switching device 10 for interrupting a high-voltage direct current flowing in an electrical conductor 11. The electrical conductor 11 may, for example, belong to a power transmission line or to a connecting bus in an HVDC network unit operating at a nominal DC service voltage exceeding 1500 V, or even exceeding 75,000 V (75 kV). The switching device 10 is therefore interposed in the electrical conductor 11, between a primary point 12 of the device 10 and a secondary point 14 of the device 10. The primary point 12 and the secondary point 14 can be connection terminals of the device 10, respectively. The switching device 10 thus divides the electrical conductor 11 into two sections: a first section 111, which is connected to the primary point 12, and a second section 112, which is connected to the secondary point 14.The switching device 10 here comprises several high-voltage circuit breakers 3 connected in series and a control circuit 2. Although several circuit breakers 3 connected in series have been illustrated, the switching device 10 may also comprise a single circuit breaker 3 between the primary point 12 and the secondary point 14.

[0025] In a conduction configuration of the switching device 10, an operational direct current flows under a high nominal voltage of R012535 PCT Depot Text.docx service of the switching device 10. This is the operational electric current flowing in the conductor 11, and whose intensity is less than or equal to the nominal intensity for the switching device 10. Indeed, in the event of an electrical fault, the intensity of the current through the switching device 10 may exceed this nominal intensity for a short time.

[0026] As illustrated in Figure 2, a circuit breaker 3 here comprises three branches which are electrically in parallel with each other between the primary point 12 and the secondary point 14. The circuit breaker 3 comprises a main conduction branch 31, a switching branch 33, and an absorption branch 34. As detailed in examples later, the absorption branch 34 can be integrated into the switching branch 33.

[0027] The main branch 31 includes a main switching device in the form of a controlled switch. The controlled switch may be of the mechanical type, for example a vacuum bulb switch 32. In a manner known per se, the switch 32 has electrodes that can be brought into contact or separated from each other to selectively allow the conduction or interruption of current through the main branch 31.

[0028] Figure 3 illustrates an example of a switching branch 33. The switching branch 33 is configured to selectively inject current into the controlled switch 32. The conduction state of the switching branch 33 is advantageously defined via a discharge activation circuit 330, typically a controlled activation switch. The switching branch 33 includes an oscillating circuit, an example of which is detailed later.

[0029] The switching branch 33 is sized so that the oscillating circuit can inject a current capable of canceling the current through the controlled switch 32. The oscillating circuit is formed here by including an inductor 331 and a capacitive circuit 332. The switching branch 33 is isolated from ground. The capacitive circuit 332 is connected in parallel with the controlled switch. This configuration allows, in particular, for a reduced size of the capacitive circuit 332, due to a smaller amplitude of the voltage applied across the terminals of the capacitive circuit 332. Whatever R012535 PCT Depot Text.docxle direction of current discharge in switching branch 33, this discharge does not pass through earth.

[0030] The switching branch 33 also includes a selection circuit 333 configured to select the direction of discharge of the capacitive circuit 332 in the piloted switch 32.

[0031] The control circuit 2 is configured to identify an opening command for the controlled switch 32, for example, upon fault detection. The control circuit 2 is also configured to identify the direction of the current flowing through the controlled switch 32. Depending on the identified current direction through the controlled switch 32, the selection circuit 333 is configured to initiate the discharge of the capacitive circuit 332 in the controlled switch 32 in the opposite direction to the identified direction.

[0032] Thus, the discharge of the capacitive circuit 332 is in the opposite direction to the fault current in the controlled switch 32 during the first half-period of the oscillating circuit: the zero crossing of the current through the controlled switch 32 therefore occurs during this first half-period of the oscillating circuit. Consequently, the oscillating circuit does not need to be designed to handle the case where the discharge of the capacitive circuit 332 is in the opposite direction to the fault current in the controlled switch 32 only during the second half-period of the oscillating circuit. The discharge current peak for which the oscillating circuit is designed is thus reduced. This proves particularly advantageous in cases where the through-resistance in the switching branch 33 is high, as this resistance increases the damping coefficient of the oscillating circuit.This proves particularly advantageous when the 330 activation switch is based on the use of semiconductor switches, such as IGBTs or thyristors.

[0033] Figure 4 illustrates an example of implementing a capacitive circuit combined with a selector circuit. The capacitive circuit includes a 3320 capacitor. The selector circuit includes a full bridge of controlled switches. The 3320 capacitor is connected within the full bridge. The 3320 capacitor can be a low-voltage capacitor whose rated voltage is independent of the line voltage. In this example, the bridge R012535 PCT Depot Text.docxcomplete is made from unidirectional conduction switches, in particular thyristors. The complete bridge thus includes thyristors 3351 to 3358.

[0034] In this example, a surge suppressor 334 is advantageously connected in parallel with the full bridge. This surge suppressor allows, for example, limiting the capacitor's charging voltage when line current flows through the switching branch 33. This surge suppressor 334 can also be used in place of the surge suppressor 34 shown in Figure 2.

[0035] This embodiment is based on selecting a direction of current discharge between terminals A and B for a predefined polarity of capacitor 3320. The operation of this embodiment can be as follows. In a preliminary step, control circuit 2 pre-charges capacitor 3320. Assuming the potential at terminal B is higher than the potential at terminal A, control circuit 2 can turn thyristors 3355 and 3354 on. Thyristors 3351 to 3353 and 3356 to 3358 remain non-conducting. Assuming the potential at terminal A is higher than the potential at terminal B, control circuit 2 can turn thyristors 3351 and 3358 on. Thyristors 3352 to 3357 remain non-conducting. The polarity of the potential across the terminals of the 3320 capacitor is therefore independent of the polarity of terminals A and B at the time of charging.

[0036] In the first configuration, it is assumed that electrode D of capacitor 3320 is at a positive potential after charging. When a fault current flows through switch 32 from secondary point 14 to primary point 12, the control circuit 2 detects this current direction and initiates a discharge of capacitor 3320 to obtain a current flowing from terminal B to terminal A. To this end, thyristors 3352 and 3357 are made conductive as shown in Figure 5. Thyristors that are not conducting are shown with dashed lines. The activation switch 330 is turned on to initiate the discharge.

[0037] In a second configuration, we will assume that electrode D of capacitor 3320 is at a positive potential after charging. In the presence of a fault current through switch 32, flowing from primary point 12 to point R012535 PCT Depot Text.docx Secondary 14, the control circuit 2 detects this direction of the current and initiates a discharge of the capacitor 3320 to obtain a current going from terminal A to terminal B. For this purpose, the thyristors 3353 and 3356 are made conductive as illustrated in figure 6. The activation switch 330 is made conductive to initiate the discharge.

[0038] In a third configuration, the electrode C of capacitor 3320 is assumed to be at a positive potential after charging. When a fault current flows through switch 32 from secondary point 14 to primary point 12, the control circuit 2 detects this current direction and initiates a discharge of capacitor 3320 to obtain a current flowing from terminal B to terminal A. For this purpose, thyristors 3355 and 3354 are made conductive as illustrated in Figure 7. The activation switch 330 is turned on to initiate the discharge.

[0039] In a fourth configuration, electrode C of capacitor 3320 is assumed to be at a positive potential after charging. When a fault current flows through switch 32 from primary point 12 to secondary point 14, the control circuit 2 detects the direction of the current and initiates a discharge of capacitor 3320 to obtain a current flowing from terminal A to terminal B. For this purpose, thyristors 3351 and 3358 are made conductive as illustrated in Figure 8. The activation switch 330 is turned on to initiate the discharge.

[0040] Figure 9 illustrates an example of the implementation of a capacitive circuit 332 combined with a selector circuit 333. The capacitive circuit includes, in particular, capacitors 3321 and 3322 connected in parallel. The selector circuit 333 comprises first and second unidirectional conduction switches 3331 and 3332, in this case thyristors. The switches 3331 and 3332 are connected in series with the first and second capacitors 3321 and 3322, respectively, with the first and second switches 3331 and 3332 exhibiting opposite directions of conduction.

[0041] Capacitors 3321 and 3322 are initially charged with opposite polarities. R012535 PCT Deposit Text.docx

[0042] This embodiment is based on selecting a capacitor for discharge according to the polarity of its charge. When a fault current flows through switch 32 from secondary point 14 to primary point 12, control circuit 2 detects this current direction and initiates a discharge of capacitor 3321 to obtain a current flowing from terminal B to terminal A. For this purpose, thyristor 3331 is turned on, as is the activation switch 330. The discharge of circuit 332 is thus initiated in the opposite direction to the fault current to quickly bring the current through switch 32 to zero. The other thyristors in the selection circuit 333 remain off.

[0043] In the presence of a fault current through switch 32 flowing from primary point 12 to secondary point 14, the control circuit 2 detects this direction of current and initiates a discharge of capacitor 3322 to obtain a current flowing from terminal A to terminal B. For this purpose, thyristor 3332 is turned on, as is the activation switch 330. The discharge of circuit 332 is therefore initiated in the opposite direction to the fault current to quickly bring the current through switch 32 to zero. The other thyristors of the selection circuit 333 remain off.

[0044] Advantageously, the capacitive circuit 332 includes capacitors 3323 and 3324 connected in parallel with capacitors 3321 and 3322. The selection circuit 333 further includes unidirectional conduction switches 3333 and 3334, similar to 3331 and 3332. Switches 3333 and 3334 are connected in series with capacitors 3323 and 3324 respectively, with switches 3333 and 3334 having opposite conduction directions.

[0045] Capacitors 3321 and 3322 are initially charged with opposite polarities. Capacitors 3323 and 3321 are initially charged with the same polarity. Capacitors 3324 and 3322 are initially charged with the same polarity.

[0046] In the presence of a fault current through the switch 32, for example going from the primary point 12 to the secondary point 14, the control circuit 2 detects this direction of the current and commands a first discharge of the circuit 332 in order to cut off the switch 32. R012535 PCT Deposit Text.docx

[0047] The control circuit initiates a discharge of capacitor 3322 to obtain a current flowing from terminal A to terminal B. For this purpose, thyristor 3332 is turned on, as is the activation switch 330. The discharge of circuit 332 is therefore initiated in the opposite direction to the fault current to quickly bring the current through switch 32 to zero. The other thyristors of the selection circuit 333 are kept off.

[0048] The control circuit 2 turns switch 32 on again to determine if the fault was merely transient. If the fault persists, a new switching cycle of switch 32 is initiated. With capacitor 3321 discharged, the control circuit 2 initiates a discharge of capacitor 3323 to obtain a current flowing from terminal B to terminal A. For this purpose, thyristor 3333 is turned on, as is the activation switch 330. The discharge of circuit 332 is thus initiated again in the opposite direction to the fault current to quickly bring the current through switch 32 to zero. The other thyristors of the selection circuit 333 remain off.

[0049] Such a configuration makes it possible to implement an open / close / open cycle in a reduced time.

[0050] Figure 10 illustrates another example of implementing a capacitive circuit 332 combined with a selection circuit. The capacitive circuit 332 includes a capacitor 3320. The capacitive circuit 332 includes a polarity reversal circuit across the capacitor 3320. The polarity reversal circuit includes two unidirectional conduction switches 3371 and 3372, connected in antiparallel; these are thyristors. An inductor 3370 is connected in series with the polarity reversal circuit. The branch including the inductor 3370 and the switches 3371 and 3372 is connected in parallel with the capacitor 3320.

[0051] The use of thyristors 3371 and 3372 (and more generally of two branches with switches controlled with a unidirectional conduction function in anti-parallel) makes it possible to achieve conduction for half a period of the oscillating circuit including the inductance 3370 and the capacitor 3320, so as to discharge one electrode of the capacitor 3320 R012535 PCT Depot Text.docx towards its other electrode to reverse the polarity of the charge, but to block conduction during the other half period, the reversed charge of the capacitor 3320 then being conserved.

[0052] The operation of this example is as follows. We will assume that electrode C of capacitor 3320 is at a negative potential after a preliminary charging stage. The activation switch 330 is held in the closed position. In the presence of a fault current through switch 32, for example, flowing from secondary point 14 to primary point 12, the control circuit 2 detects this direction of the current and requires a discharge of the switching branch 33 in order to open switch 32. It can be noted that the polarity of the charge on capacitor 3320 would not allow, during the first half-cycle of oscillation, a current opposite to the fault current in switch 32 if switch 330 were turned on.

[0053] Thus, the control circuit 2 turns on thyristor 3371 and keeps thyristor 3372 in a non-conducting state. During the first half-cycle of oscillation, the positive charge flows from electrode D to electrode C. The intrinsic diode of thyristor 3371 prevents the current in the oscillating circuit from reversing before the next half-cycle begins. Both thyristors 3371 and 3372 are held in a non-conducting state. The activation switch 330 is then turned on to inject the discharge current, thereby canceling the current in switch 32.

[0054] In this example, a surge protector 334 is advantageously connected in parallel with the capacitor 3320 and the selection circuit.

[0055] Figure 11 illustrates an example of an embodiment of an activation switch 330 that can be used for a circuit breaker 3 according to the invention. The 330 activation switch comprises a complete diode bridge 3301 to 3304. A unidirectional voltage and current semiconductor switch 3305 (here an IGBT transistor, which can also be of type IGCT, IEGT, GTO, or ETO, for example) is connected in the diode bridge. This variant allows the use of a single 3305 semiconductor switch, thus providing a low-cost 330 activation switch. R012535 PCT Deposit Text.docx

[0056] In the illustrated example, a surge protector 336 is connected in parallel with the diode bridge. The surge protector 336 allows, in particular, the balancing of the voltages of several circuit breakers 3 if they are connected in series. This surge protector 336 can also be used in place of the surge protector 34 shown in Figure 2.

[0057] Figure 12 illustrates another example of an embodiment of an activation switch 330 that can be used for a circuit breaker 3 according to the invention. The activation switch 330 comprises two switches 3308 and 3309 connected in anti-series, here of the IGBT transistor type (which can also be of the IGCT, IEGT, GTO, or ETO type, for example). Diodes 3306 and 3307 are connected in parallel with switches 3308 and 3309, respectively. Compared to the variant in Figure 11, this variant reduces the conduction resistance of the activation switch 330. R012535 PCT Deposit Text.docx

Claims

Demands

1. [High-voltage circuit breaker (3), characterized in that it comprises: -a main conduction branch (31) comprising a controlled switch (32) to define the conduction state through the main branch (31); -a switching branch (33) configured to selectively inject a current into the controlled switch (32), the switching branch (33) comprising an oscillating circuit including at least one inductor and a capacitive circuit (332) sized to cancel the current through the controlled switch (32), the switching branch also comprising a selection circuit (333) configured to select the direction of discharge of the capacitive circuit (332); -an activation switch (330) configured to selectively cut or conduct current in the switching branch (33); -a control circuit (2) configured to identify the direction of the current through the controlled switch (32) and configured to drive the selection circuit (333) and the activation switch (330) to selectively initiate the discharge of the capacitive circuit in the controlled switch in a direction opposite to the identified direction of the current through the controlled switch (32).

2. High voltage circuit breaker (3) according to claim 1, wherein the capacitive circuit includes (332) a capacitor (3320), the selection circuit (333) being configured to reverse the connection of the electrodes of this capacitor to terminals of the switching circuit (33).

3. High voltage circuit breaker according to claim 2, comprising a complete bridge of switches controlled by the control circuit (2), said capacitor (3320) being connected in the complete bridge.

4. High-voltage circuit breaker (3) according to claim 1, wherein the capacitive circuit (332) comprises first and second capacitors (3321, 3322) connected in parallel, the selection circuit (333) comprising first and second unidirectional conduction switches (3331, 3332) connected respectively in series with the R012535 PCT Depot Text.docx first and second capacitors (3321, 3322), the first and second switches (3331, 3332) having opposite directions of conduction.

5. High voltage circuit breaker (3) according to claim 4, wherein the capacitive circuit (332) comprises third and fourth capacitors (3323, 3324) connected in parallel with the first and second capacitors (3321, 3322), the selection circuit (333) comprising third and fourth unidirectional conduction switches (3333, 3334) connected respectively in series with the third and fourth capacitors (3323, 3324), the third and fourth switches (3333, 3334) having the same direction of conduction as the first and second switches respectively, the control circuit (2) being configured to make the third switch conduct when the first capacitor is discharged and configured to make the fourth switch conduct when the second capacitor is discharged.

6. A high-voltage circuit breaker (3) according to claim 1, wherein said capacitive circuit comprises a capacitor (3320), wherein said selection circuit comprises a circuit for reversing the polarity of the capacitor charge and another inductor, said selection circuit being configured to selectively connect the capacitor and the other inductor in parallel to form an LC circuit for half a period of oscillation of said LC circuit, before the activating switch (330) initiates said discharge of the capacitive circuit into the controlled switch.

7. A high-voltage circuit breaker (3) according to any one of the preceding claims, wherein the activating switch (330) comprises several semiconductor switches connected in series.

8. High voltage circuit breaker (3) according to any one of claims 1 to 6, wherein the activation switch (330) comprises a full diode bridge (3301, 3302, 3303 and 3304) and a unidirectional current or voltage semiconductor switch (3305) connected in the diode bridge.

9. High-voltage circuit breaker (3) according to any one of claims 1 to 6, wherein the activation switch (330) comprises R012535 PCT Depot Text.docx two switches (3308, 3309) connected in anti-series and two diodes (3306, 3307) connected in parallel with said two switches (3308, 3309) respectively.

10. High voltage circuit breaker according to any one of the preceding claims, further comprising a surge arrester (334) connected to the terminals of the selection circuit (333).

11. High voltage circuit breaker according to any one of the preceding claims, wherein the switching branch (33) is isolated from earth.

12. A method for controlling a high-voltage circuit breaker (3) comprising a main conduction branch (31) including a controlled switch (32) for defining the conduction state through the main branch (31), a switching branch (33) configured to selectively inject current into the controlled switch (32) and comprising an oscillating circuit including at least one inductor and a capacitive circuit (332) sized to cancel the current through the controlled switch (32), a selection circuit (333) configured to select the direction of discharge of the capacitive circuit (332), an enabling switch (330) configured to selectively interrupt or conduct the current in the switching branch (33), the method comprising the steps of: -identify the direction of the current flowing through the controlled switch (32); -command the switching off of the controlled switch (32); -via the selection circuit (333) and the activation switch (330), initiate the discharge of the capacitive circuit in the controlled switch in a direction opposite to the identified direction of the current through the controlled switch (32).

13. A method for controlling a high-voltage circuit breaker (3) according to claim 12, wherein said discharge of the capacitive circuit is followed by a closing of the controlled switch (32), then by a further opening of the controlled switch and the initiation of a further discharge of the capacitive circuit in the controlled switch in the opposite direction to the identified direction of the current flowing through the controlled switch (32). R012535 PCT Deposit Text.docx

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