Method for testing a high-voltage circuit breaker equipped with an injection circuit

Abstract

The invention relates to a method for testing a high-voltage current-injection circuit breaker (1) including a plurality of series-connected current-injection switch modules (3) comprising a main branch (31) equipped with an electrical cut-off member (32) through which a high-voltage current flows, and comprising a switching branch (33) configured to selectively inject a current into the main branch (31) so as to cancel out the current in this main branch, the method comprising the following steps: - while keeping the electrical cut-off member (32) of a module in its on state, activating the switching branch (33) of this module in order to inject a current into the main branch of this module; - determining electrical parameters in the module during this activation; - determining whether the circuit breaker (1) has failed by comparing the determined electrical parameters with reference electrical parameters.

Description

Description Title of the invention: Method for testing a high-voltage circuit breaker equipped with an injection circuit

[0001] The invention relates to electrical networks, and in particular to the functionality tests of high voltage circuit breakers equipped with an injection circuit.

[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 the closed position to ensure the conduction of current but must be able to interrupt this current when a fault occurs.

[0003] To ensure that the power interruption will function correctly when a fault occurs, the current solution is to perform maintenance operations by isolating the circuit breakers from the network and carrying out various tests and inspections. During the inspection, the equipment connected to the circuit breaker must be kept switched off.

[0004] 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.

[0005] 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 branch. The main branch typically includes a mechanical switch configured to be held selectively open or closed. The parallel branch includes a circuit configured to inject current into the main branch to force a zero crossing of the current through the mechanical switch when the circuit breaker is opened. During a fault, when a circuit breaker opening command is generated, the current injection creates a zero crossing of the current through the mechanical switch, allowing the circuit to close. R012391 FR PCT Text.docx thus the interruption of the arc between the contacts of this mechanical switch which will simply have to hold the resulting voltage in order to avoid a re-ignition of the arc in this switch.

[0006] For safety reasons, it is essential to verify that a circuit breaker is functioning correctly before using it in the event of a fault. Indeed, a circuit breaker failure should not only be detected during operation, otherwise the safety of the installations is no longer guaranteed. To anticipate such a failure, a current-injection circuit breaker is disconnected from the network to allow for a physical inspection.

[0007] Inspecting a current-injection circuit breaker can be relatively time-consuming due to its greater complexity and requires grounding the installation. Furthermore, such an inspection during maintenance is not a sufficient guarantee of the correct operation of the current-injection circuit breaker in the event of a fault. If the circuit breaker fails during an attempted interruption, other adjacent circuit breakers must take over. In such a configuration, energy transmission losses increase, potentially creating instabilities or even a collapse in the electrical grid voltage.

[0008] The invention aims to resolve one or more of these drawbacks. The invention thus relates to a method for testing a high-voltage current-injection circuit breaker as defined in claim 1.

[0009] The invention also relates to variants of the dependent claims. Those skilled in the art will understand that each of the features of the variants 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.

[0010] The invention also relates to a high-voltage current injection circuit breaker as defined in the attached claims.

[0011] 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: R012391 FR PCT Text.docx

[0012] [Fig.1] is a schematic representation of an example embodiment of a high-voltage electric current cutting device according to the invention;

[0013] [Fig.2] is a schematic representation of another example of an embodiment of a high-voltage electric current interruption device according to the invention;

[0014] [Fig.3] is a schematic representation of an example of a current injection switch module;

[0015] [Fig.4] schematically illustrates a first example of a switching branch configured to selectively inject current into the main branch;

[0016] [Fig.5] schematically illustrates a second example of a switching branch configured to selectively inject current into the main branch;

[0017] [Fig.6] schematically illustrates an example of a switching branch 33 configured to selectively apply a transient voltage peak across the terminals of the main branch 31;

[0018] [Fig.7] schematically illustrates a third example of a switching branch configured to selectively inject current into the main branch;

[0019] [Fig.8] schematically illustrates a fourth example of a switching branch configured to selectively inject current into the main branch;

[0020] [Fig.9] schematically illustrates a fifth example of a switching branch configured to selectively inject current into the main branch;

[0021] [Fig.10] schematically illustrates a sixth example of a switching branch configured to selectively inject current into the main branch;

[0022] [Fig.11] illustrates an example of electrical parameters determined for a module according to figure 4; R012391 FR PCT Text.docx

[0023] [Fig.12] illustrates an example of electrical parameters determined for a module according to figure 5;

[0024] [Fig.13] illustrates an example of electrical parameters determined for a module according to figure 6;

[0025] [Fig.14] illustrates a variant of the switching branch of figure 7;

[0026] [Fig.15] schematically illustrates a charger implemented for a test.

[0027] Figure 1 illustrates a first example of the implementation of a high-voltage current-injection circuit breaker 1. The circuit breaker 1 is designed to interrupt a high-voltage electric current (which can be alternating or direct) flowing in an electrical conductor 11. The electrical conductor 11 may, for example, belong to an electrical power transmission line in an HVDC network unit that operates at a nominal continuous service voltage greater than 1500 V, or even greater than 75,000 V (75 kV).

[0028] The circuit breaker 1 is therefore interposed in the electrical conductor 11, between a primary point 12 and a secondary point 14. The primary point 12 and the secondary point 14 can be connection terminals for the circuit breaker 1, respectively. The circuit breaker 1 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. As is known, the circuit breaker 1 can switch between a conducting state, in which it allows the flow of electric current between the primary point 12 and the secondary point 14, and an isolation state, in which it interrupts the current between the primary point 12 and the secondary point 14. The circuit breaker 1 must also ensure switching between the conducting state and the isolation state and vice versa. The circuit breaker 1 comprises a set 10 of current-injection switch modules 3 connected in series.

[0029] Assembly 10 is configured here to fulfill the role of the circuit breaker, namely that it has the capacity to interrupt a current lower than its breaking capacity, therefore either under load at the rated or partial current, or in the presence of a fault current. In particular, it can be predicted that for n modules connected in series in the circuit breaker, the breaking capacity of n-1 modules 3 R012391 FR PCT Text.docx be greater than the breaking capacity of circuit breaker 1, so that branch 31 of a module 3 to be tested can be made conductive without risking compromising the protection of circuit breaker 1. Examples of modules 3 will be detailed later.

[0030] Figure 2 illustrates a second example of the implementation of a high-voltage current-injection circuit breaker 1. The circuit breaker 1 is also designed to interrupt a high-voltage (typically direct) electric current flowing in an electrical conductor 11.

[0031] The circuit breaker 1 is therefore interposed in the electrical conductor 11, between a primary point 12 and a secondary point 14. The circuit breaker 1 comprises a set 10 of current-injection switch modules 3 connected in series. Examples of modules 3 will be detailed later.

[0032] A residual current switch 4 is connected in series with assembly 10. The residual current switch 4 has the capacity to interrupt a current less than or equal to the breaking capacity of assembly 10. This residual current switch can be replaced by a disconnect switch. This residual current switch or disconnect switch can be placed on the side of the primary point 12 or the secondary point 14 of assembly 10, in order to isolate assembly 10 from the switch modules. It is permissible to place this residual current switch 4 at points 11 and 12 in order to isolate the main circuit breaker 10.

[0033] In the examples in Figures 1 and 2, a control circuit 2 is configured to drive modules 3 and switch 4 if necessary.

[0034] Figure 3 is a schematic representation of an example of a current-injection switch module 3. The module 3 comprises a main branch 31, equipped with an electrical breaking element 32, known per se. The electrical breaking element 32 can be of the mechanical type (for example, a vacuum tube) or semiconductor type, depending on the configuration. In a mechanical breaking element 32, the electrical interruption is achieved by displacement, in particular by separation, of one or more pairs of electrical contacts. The displacement of the electrical contacts is then generally carried out by mechanical operating elements or actuators. R012391 FR PCT Text.docx pneumatic, hydraulic, or electrical. In the presence of a significant current and / or voltage, the mechanical separation of the electrical contacts can result in the formation of an electric arc between the two electrical contacts of the device. As long as the electric arc remains established across the mechanical separation, the switching element 32 does not perform the electrical interruption because a current continues to flow through the switch due to the presence of the arc.

[0035] Module 3 further includes a switching branch 33, connected in parallel with the main branch 31. The switching branch 33 is configured to be selectively activated or deactivated. The switching branch 33 is deactivated when the main branch must be maintained in its conducting state. The switching branch 33 is activated upon receiving an opening command for the main branch 31, in order to assist the opening of this main branch 31. Depending on the configuration, the switching branch 33 is configured either to selectively inject current into the main branch 31 so as to transiently cancel the current in this main branch 31, or to selectively apply a transient voltage spike across the terminals of this main branch 31.

[0036] Module 3 advantageously includes a surge arrester 34, connected in parallel with the main branch 31. The surge arrester 34 is designed to limit the magnitude of the potential difference across the main branch 31. A surge arrester generally comprises an electrical component whose resistance varies according to the voltage across its terminals. The surge arrester acts as a voltage limiter across its terminals within the current range for which it was selected. It opposes the protection voltage when the highest current for which the surge arrester was designed is applied. Below the transition voltage, it tends to prevent current flow. Above the transition voltage, it allows current to flow through the surge arrester for a small increase in the voltage across its terminals.Among surge protectors, we know in particular the lightning arresters, which can include varistors and "TVS" (Transient Voltage Suppressor) diodes, such as "Transil™" diodes. R012391 FR PCT Text.docx

[0037] Figure 4 schematically illustrates a first example of a switching branch 33 configured to selectively inject current into the main branch 31. In this configuration, the switching branch 33 includes an enabling switch 330, an inductor 331, and a capacitor 332 connected in series. The switching branch 33 also includes a circuit comprising a resistor 333 and a switch 334 connected in parallel, this circuit being connected in series with the capacitor 332. The switch 334 allows selective modification of the characteristic time (the characteristic time corresponding to the time constant in aperiodic operation and to the period in periodic operation) of the switching branch 33.

[0038] Figure 5 schematically illustrates a second example of a switching branch 33 configured to selectively inject current into the main branch 31. In this configuration, the switching branch 33 includes an enabling switch 330, an inductor 331 and a capacitor 332 connected in series.

[0039] In the examples in Figures 4 and 5, capacitor 332 is pre-charged and switch 330 is held open when the main branch 31 is conducting in a steady state, i.e., when circuit breaker 1 is in the conducting configuration. Activation of the switching branch 33 is achieved by closing the activation switch 330. Upon receiving a command to open the main branch 31, the activation switch 330 closes, inducing a current discharge in the main branch 31. This discharge allows the breaking element 32 to open when the current flowing through it crosses zero. When the breaking element 32 interrupts the circuit, the voltage across capacitor 332 rises until transient current conducts through the surge arrester 34, and capacitor 332 is thus recharged for subsequent activation.

[0040] In the example in Figure 4, switch 334 can be switched during discharge, in order to analyze its effect on the discharge and verify its functionality. R012391 FR PCT Text.docx

[0041] According to the invention, a test method for the circuit breaker 1 is implemented as follows with current injection, for example, as shown in Figures 4 and 5. By holding the switching element 32 in its conducting state, the switching branch 33 is activated to inject current into the main branch 31. Electrical parameters are determined in the module 33 for this activation. Optionally, all the components of the switching branch 33 can be switched sequentially to measure their effect. The parameters can be determined by measurement, calculation, or simulation. The switching branch 33 of a tested module 3 can be returned to its state ready to perform a current injection to interrupt the main branch 31.

[0042] In certain configurations, these electrical parameters can be determined asynchronously with respect to activation. Various examples of determined electrical parameters will be detailed later. These determined electrical parameters are compared to reference electrical parameters. Examples of reference electrical parameters will be detailed later. A processing device, which can, for example, be integrated into circuit 2, determines whether circuit breaker 1 (and in particular module 3) has failed, has performance drift, or whether one or more of its components have characteristic drift, based on this comparison.

[0043] Such a test can be performed when circuit breaker 1 is in operation, either in its steady-state conducting state or in a transient interrupting state. An in-service test of circuit breaker 1 increases the testing frequency and allows for the detection of a fault in circuit breaker 1 before it manifests as a fault. Furthermore, it is not necessary to disconnect circuit breaker 1 from the network or to perform a physical inspection to implement such a test. Therefore, circuit breaker 1 can carry a continuous operating current before, during, and after the test (i.e., after current injection), while in its steady-state conducting state.

[0044] In a steady-state operation, all three modules are conducting, and if applicable, the residual current device 4 is also conducting. In this state, a service current flows through the circuit breaker 1 when the branch of R012391 FR PCT Text.docx Switching branch 33 is activated. The switching branches 33 of the different modules can be activated sequentially. For testing each module 3, the activation tasks of the switching branch 33 can be performed without opening the switching element 32 of that module. The switching element 32 of the module is then held open beyond the activation of the switching branch 33 and the corresponding injection. During a test, module 3 can no longer participate in interrupting the current through assembly 10. However, by simultaneously keeping a sufficient number of modules 3 out of their test mode, a potential interruption of the current through assembly 10 is still guaranteed even during a test phase.

[0045] Circuit breaker 1 can either have just the number of modules 3 sufficient to interrupt a fault current under full network voltage (configuration without redundancy), or have at least one additional module 3 compared to this breaking capacity (configuration with redundancy).

[0046] In the configuration without redundancy, circuit breaker 1 cannot interrupt a full-voltage fault current during a test phase. Circuit breaker 1 is considered locked in its stationary state. The test operations described previously can be performed on all 3 modules simultaneously or sequentially.

[0047] In the redundant configuration, a sufficient number of modules 3 are maintained simultaneously to interrupt the high-voltage fault current. Test operations can be performed simultaneously on the number of redundant modules 3 without affecting the breaking capacity. In a transient breaking state, several modules 3, and possibly the residual current switch 4, are in a transient breaking state. Thus, the test procedure can include preliminary steps of fault detection, followed by breaking the residual current switch 4 or a sufficient number of modules 3. Activation of a switching branch 33 of a module 3 can therefore be implemented while the residual current switch 4 or other modules 3 are held open. The determination of the electrical parameters in the module 3 is then carried out during this activation.Subsequently, the switch 4 or all of the other modules 3 are closed. R012391 FR PCT Text.docx

[0048] In the case of the embodiment according to figure 4, for the purpose of a steady-state test, the injection of a current by the switching branch 33 is advantageously carried out by discharging the capacitor 332 over a period at least equal to one hundredth of the characteristic time of this switching branch 33. Such a discharge makes it possible to obtain information in order to carry out the comparisons described later.

[0049] For testing purposes, the injection of an oscillating current through switching branch 33 is advantageously achieved by discharging capacitor 332 for a duration at least equal to one-quarter of the period of this switching branch 33. Such a discharge provides information for the comparisons described later. Advantageously, the discharge of capacitor 332 is carried out over a duration equal to an integer multiple of half the period of this switching branch 33. Such a discharge allows a significant charge to be maintained in capacitor 332, thus reducing its recharge time if the next activation occurs within a short interval.

[0050] For example, a 332 capacitor loses capacitance as it ages. This capacitance can be determined from an oscillation frequency measured during a test activation.

[0051] For the example in Figure 4, the following sequence can be implemented when testing the open branch 31: -Measure the pre-charge voltage Vp332 across capacitor 332, after commanding switch 330 to close, plus the time required for switch 330 to close and before it opens again, for example, due to lack of current or on command. The pre-charge voltage corresponds to the voltage Vp332 just before switch 330 closes; -make switch 330 conductive; -measure the voltage V32 across the terminals of the switching element 32 when the current through the switch 330 falls below a threshold; -measure the current flowing through capacitor 332. R012391 FR PCT Text.docx

[0052] Determining the fault following the voltage measurement test can follow the following logic: -deduce that switch 330 is operational if the following relationship is verified |(Vp332 - V32) / Vp332| <1%. We can also deduce that the switching device 32 and the surge protector 34 withstand the voltage; -deduce that the switching device 32 or the surge protector 34 is defective if the following relationship is verified |(Vp332 - V32) / Vp332| >30%. On the other hand, we can deduce that the switch 330 is operational; -deduce that the switching device 32 and the surge protector 34 are operational but that there is an insulation fault in module 3 if the current in capacitor 332 is greater than the leakage current of surge protector 334.

[0053] For the various examples, the impedance value can be determined based on the peak voltage and peak current in the switching branch 33. The capacitance of capacitor 332 can be determined based on the frequency or period of the discharge current and the impedance of the branch. For example, the impedance Z33 of this branch will be defined by Z33 = Vp32 / Ip33, where Vp32 is the peak voltage across capacitor 332 and Ip33 is the peak current in the switching branch 33. The capacitance of capacitor 332 can then be determined as C332 = 1 / (2 * TT * f * Z33), where f is the discharge frequency, and, if applicable, the value of the inductance L331 can be determined by L331 = Z33 / (2 * TT * f). The frequency f depends on the capacitance, inductance, and resistance values ​​by the relation (2 * TT * f). 2 = (1 / (L*C)) - (R / (2*L)) 2 The resistance R can be deduced from two current extrema.

[0054] Figure 6 schematically illustrates an example of a switching branch 33 configured to selectively apply a transient voltage peak across the terminals of the main branch 31. In this configuration, the switching branch 33 includes a driven voltage source 335 connected in series with an inductor 3351 and a capacitor 3352.

[0055] The switching branch 33 is activated by controlling the controlled voltage source 335, so as to selectively apply a voltage spike across the terminals of the main branch 31. By maintaining the element of R012391 FR PCT Text.docx With the cutoff 32 in its cutoff state, the switching branch 33 is activated so that the controlled voltage source 335 applies a voltage peak across the terminals of the main branch 31. In practice, the voltage applied by the source 335 is much lower than the voltage required to obtain the conduction of the surge suppressor 34.

[0056] During this activation, electrical parameters are determined in module 3. These determined electrical parameters are compared to reference electrical parameters. A processing device determines whether circuit breaker 1 (and in particular module 3) has failed based on this comparison.

[0057] More specifically, the switching element 32 is held in its conducting state, and the switching branch 33 is activated, along with the controlled voltage source 335. Optionally, all the components of the switching branch 33 can be switched or activated sequentially to measure their effect. The switching branch 33 of a tested module 3 can then be returned to its state ready to inject a switching current into the main branch 31.

[0058] Figure 7 schematically illustrates an example of another switching module 33. In this example, the switching module 33 includes a capacitor 332 and a capacitor charger 336. The charger 336 is configured to selectively apply a voltage across the capacitor 332 to ensure its charging. The charger 336 is configured to apply the charging voltage across the capacitor 332 via a resistor 339. In parallel with the capacitor 332 and the load resistor 339, a branch is connected comprising a controlled switch 337 and an impedance 338 connected in series. This branch is connected to one terminal of the capacitor 332. By appropriately controlling the controlled switch 337 and the charger 336, a discharge of the capacitor 332 through the impedances 338 and 339 can be initiated for testing purposes.By deactivating the charger 336, the controlled closure of the switch 337 causes the discharge of the capacitor 332 into the total impedance presented by the elements 338 and 339. The analysis of the current and voltage curves recorded respectively in the capacitor 332 and at its terminals is a. R012391 FR PCT Text.docx This characteristic can be measured regularly throughout the lifetime of circuit breaker 1. The current flowing through switch 337, the impedance of 338, the impedance of 339, and the voltage across their terminals can also be measured and analyzed. This analysis can result in a measurement of the variation in capacitance and therefore the performance of circuit breaker 1 over time.

[0059] Figure 8 schematically illustrates an example of another switching module 33. This example differs from the example in Figure 7 by the replacement of resistor 339 with resistor 3392. A resistor 3391 is also added between the charger 336 and the connection node between resistors 338 and 3392.

[0060] Figure 9 schematically illustrates an example of another switching module 33. In this example, the switching module 33 includes a capacitor 332 and a capacitor charger 3353. The capacitor 332 is connected in series between unidirectional semiconductor switches 3357 and 3358. The capacitor 332 also serves as a power supply for a control system 3359. Branch 33 enables the opening functions of the switch 32 to be performed with a switching capacitor 332 having a voltage rating much lower than the nominal operating voltage of the network into which the electrical conductor 11 is inserted.

[0061] Alternatively, the control system 3359 advantageously includes a pre-charge circuit for the switching capacitor 332. This pre-charge circuit applies a predetermined electrical voltage between the two plates of the capacitor 332 before any switching of the switching element 32. In the example, the pre-charge circuit includes a DC voltage source 3353 that selectively applies a voltage across the capacitor 332. This voltage is applied through a resistor 3354 and another resistor 3355. The resistors 3354 and 3355 of the pre-charge circuit may have the same resistance value or different values. In practice, only one of the two resistors may be sufficient. The resistor(s) 3354, 3355 limit the charge / discharge current supplied by the DC voltage source 3353. This allows the control system 3359 to be powered by its capacitor. R012391 FR PCT Text.docx 332, a DC / DC converter may be interposed between the control system 3359 and this capacitor 332 or may be contained within the control system 3359.

[0062] Branch 33 includes, electrically in parallel with the switching capacitor 332, a switching surge suppressor 3356. This switching surge suppressor 3356 is connected at its two terminals on either side of the switching capacitor 332. The switching surge suppressor 3356 limits the voltage across the switching capacitor 332, thus allowing the use of lower voltage capacitors. Such a surge suppressor 3356 is, for example, of the ZnO type.

[0063] Switches 3357 and 3358 are IGBTs (Insulated Gate Bipolar Transistors). IGBTs 3357 and 3358 are configured in opposite directions. Together, they form a bidirectional switch capable of selectively conducting or blocking current in both directions. Using two IGBTs, 3357 and 3358, provides a bidirectional switch for both current and voltage.

[0064] Figure 10 illustrates another embodiment of a switching branch 33. The switching branch 33 here incorporates the capacitor 332, switching surge suppressor 3356, DC voltage source 3353, control system 3359, resistor 3354, and resistor 3355 from the example in Figure 9. The branch 33 includes a plasma tube switch 3300, connected in series with the inductor 331. The switch 3300 has an anode, a cathode, and a control grid housed in a sealed enclosure containing a fluid that can be ionized to generate a plasma. In a manner known per se, the control grid is arranged between the anode and the cathode such that when a control voltage is transiently applied to the control grid, a plasma path is initiated between the anode and the cathode to conduct a significant electric current.The plasma path can be interrupted by inducing a reverse bias in the control grid. The conduction state of switch 3300 is controlled via control system 3359. R012391 FR PCT Text.docx

[0065] Figure 14 illustrates a variant of the switching branch 33 of Figure 7. In this example, the switch 337 is replaced by a diode 3370, whose anode is connected to the negative terminal of the charger 336. The control of the capacitor 332 can be carried out by reversing its polarity during a test discharge.

[0066] The electrical parameters determined during activation are advantageously selected from the group comprising: a current through the main branch 31 of module 3, a current injected by the switching branch 33 of module 3, a current in an absorption branch (such as the surge arrester 34) connected in parallel with the main branch 31, a current entering or leaving the circuit breaker 1, the current slopes of the switching branch 33 at the zero crossing of the current in the main branch 31, the voltage of an injection capacitor 332 of the switching branch 33, the voltage across the terminals of the controlled voltage source 335, the voltage across a short-circuit switch 334 of a discharge resistor 333 and the voltage across the terminals of the main branch 31 of module 3. Suitable probes or calculators will be used to measure or determine these electrical parameters.Calculations or processing can be implemented to compare the determined electrical parameters with reference electrical parameters.

[0067] The reference electrical parameters are advantageously selected from the group comprising: -(more for a measurement) an activation response time, a recharge time of the switching branch 33, the amplitude of the current injected by the switching branch 33, the amplitude of a voltage across the terminals of a discharge component of the switching branch 33 (and in particular the observation that a setpoint voltage is indeed reached across the terminals of the discharge component), the frequency of the current injected by the switching branch 33, and the shape of the envelope of the current injected by the switching branch, a current slope of a controllable voltage source 335 of the switching module 33; -(further after calculation or processing) the capacitance of an injection capacitor 332 of the switching branch 33, an inductance 331 of the branch R012391 FR PCT Text.docx switching, a discharge resistance 333, the resistance of the switching branch 33, the impedance of the switching branch 33, a current slope of a controllable voltage source 335 of the switching module 33, a power consumption of a charging circuit of the discharge component.

[0068] Comparison with reference electrical parameters makes it possible to identify deviations in the electrical characteristics of certain components of module 3.

[0069] Figure 15 schematically illustrates a 336 charger, which can be used in a test procedure. A 336 charger typically includes a control circuit to stabilize the voltage across its terminals at a setpoint value. During a test, the load can be inhibited, and the voltage across the 336 charger or the current flowing through it can be monitored. Some 336 chargers are configured to transmit these measurements externally, which can eliminate the need for additional probes. The measurement time during the test depends in particular on the characteristic time corresponding to (R339+R3361 )*C332, with R339 the value of the resistance 339 in the example of figure 7, R3361 the value of the internal resistance of the charger 336 and C332 the capacitance of the capacitor 332. The test time is dependent on the accuracy of the measurements and may reach the duration (R339+R3361 )*C332, or even a multiple of this value.

[0070] Figure 11 illustrates an example of electrical parameters determined for a module 3 according to Figure 4 during a test activation of the switching module 33. The upper diagram illustrates the voltage across capacitor 332, and the lower diagram illustrates the current through capacitor 332. Switch 330 is closed at time t1, while switch 334 is held open. At time t2, switch 334 is closed, triggering an oscillatory discharge.

[0071] Figure 12 illustrates an example of electrical parameters determined for a module 3 according to Figure 5 during a test activation of the switching module 33. The top diagram illustrates the voltage across capacitor 332, and the bottom diagram illustrates the capacitor current. R012391 FR PCT Text.docx 332. Switch 330 is turned on at time t1, triggering an oscillatory discharge of capacitor 332.

[0072] Figure 13 illustrates an example of electrical parameters determined for a module 3 according to Figure 6 during a test activation of the switching module 33. The current through any of the components of 33, of the type 3351, 335, or 3352, is measured. The voltage as a function of time shown in the upper graph of Figure 13 represents, for example, the voltage across inductor 3351. The lower graph of Figure 13 corresponds to the current through inductor 3351.

[0073] The determination of a possible fault of circuit breaker 1 can be implemented during activation or offline, by analysis by a dedicated processing system.

[0074] If a fault is identified at the end of the test, the operator of circuit breaker 1 can either consider taking it out of service by short-circuiting or disconnecting it for maintenance or updating its control parameters, taking into account the measurements taken. R012391 FR PCT Text. docx

Claims

Demands

1. A method for testing a high-voltage current-injection circuit breaker (1), the high-voltage current-injection circuit breaker comprising several current-injection switch modules (3) connected in series, each module (3) comprising a main branch (31) provided with an electrical breaking element (32) through which a high-voltage current flows in the conduction configuration of the circuit breaker (1), and comprising a switching branch (33) configured to either selectively inject a current into the main branch (31) so as to cancel the current in that main branch, or selectively apply a voltage spike across the terminals of the main branch, the method comprising the steps of: -by maintaining the electrical breaking element (32) of a module in its conducting state, activate the switching branch (33) of this module to inject a current into the main branch of this module, all the electrical breaking elements of the circuit breaker (1) being maintained conducting during said activation of the switching branch (33) when said electrical breaking element (32) of the module (3) is maintained conducting, a current passing through the circuit breaker during said activation of the switching branch (33); -determine electrical parameters in the module, these electrical parameters being the electrical parameters in the module during said activation; -by comparing the determined electrical parameters with reference electrical parameters, determine if the circuit breaker (1) is faulty.

2. A method for testing a circuit breaker (1) according to claim 1, wherein a residual current switch (4) is connected in series with said modules (3).

3. A method for testing a circuit breaker according to claim 2, wherein, when said electrical breaking element (32) of the module is kept open, the residual current switch (4) is kept open during said activation of the switching branch (33). R012391 FR PCT Text.docx

4. A method for testing a circuit breaker according to claim 2, further comprising the steps of: detecting a fault, said activation of the switching branch (33) being implemented during the opening of the residual current switch, closing the residual current switch (4), determining the end of the fault, and then closing the residual current switch after said determination of the electrical parameters.

5. A method for testing a circuit breaker according to any one of the preceding claims, wherein said determined electrical parameters are selected from the group comprising: a current through the main branch of said module, a current injected by said switching branch of the module, a current in an absorption branch connected in parallel with the main branch of the module, a current entering or leaving the circuit breaker, the zero-crossing current slopes of the switching branch current, the voltage of an injection capacitor of the switching branch, the voltage across an activation switch of the switching branch (32), the voltage across a short-circuit switch (334) of a discharge resistor (333) and the voltage across the main branch of the module.

6. A test method for a circuit breaker according to claim 5, wherein said reference electrical parameters are selected from the group comprising: an activation response time, a switching branch recharge time, the amplitude of the current injected by the switching branch, zero-crossing times of one of the determined electrical parameters, the amplitude of a voltage across a discharge component of the switching branch, the frequency of the current injected by the switching branch, and the shape of the envelope of the current injected by the switching branch, the capacitance of a switching branch injection capacitor, the switching branch inductance, a discharge resistance, the switching branch resistance, the switching branch impedance, a current slope of a controllable voltage source of the switching module,a minimum withstand voltage for the absorption branch. R012391 FR PCT Text.docx

7. A method for testing a circuit breaker according to any one of the preceding claims, wherein the switching branches of the modules each include a current injection capacitor (332).

8. A method for testing a circuit breaker according to any one of claims 1 to 5, wherein the switching branches (33) of the modules each comprise a piloted voltage source (335).

9. A method for testing a circuit breaker according to any one of the preceding claims, wherein a number n of switch modules (3) are connected in series, the breaking capacity of n-1 switch modules being greater than the nominal breaking capacity of the circuit breaker (1).

10. A method for testing a circuit breaker according to any one of the preceding claims, wherein each module comprises an absorption branch (34) connected in parallel with its main branch (31).

11. High-voltage current-injection circuit breaker (1) characterized in that it includes: -several current injection switch modules (3) connected in series, each module (3) comprising a main branch (31) equipped with an electrical breaking element (32) through which a high voltage current flows in the conduction configuration of the circuit breaker (1), and comprising a switching branch (33) configured to either selectively inject a current into the main branch (31) so as to cancel the current in this main branch, or selectively apply a voltage spike to the terminals of the main branch; -a control circuit, configured to maintain the electrical breaking element (32) of a module in its conducting state, and to activate the switching branch (33) of that module to inject a current into the main branch of that module during this maintenance and while a current flows through the circuit breaker, and to maintain all the electrical breaking elements of the circuit breaker (1) conducting during said activation of the switching branch (33) when said electrical breaking element (32) of the R012391 FR PCT Text.docx module (3) is kept conducting; the control circuit being further configured to determine electrical parameters in the module, these electrical parameters being the electrical parameters in the module during said activation, and configured to, by comparison of the determined electrical parameters with reference electrical parameters, determine whether the circuit breaker (1) has failed. R012391 FR PCT Text. docx

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