ELECTRICAL CIRCUIT SHUTDOWN DEVICE WITH OVERVOLTAGE PROTECTION AND SHUTDOWN METHOD FOR IT

Description

[0001] The present invention relates to an electrical circuit interruption device with overvoltage protection, and an associated electrical circuit interruption method.

[0002] The invention applies in particular to static type breaking devices, semiconductor(s), in particular of the SSCB (for "solid state circuit breaker") or SCCB (for "SemiConductor circuit breaker") type.

[0003] This type of static disconnect device is advantageously used in direct current (DC) electrical distribution systems. In such systems, an electrical fault causes a rapid current surge, necessitating a very quick disconnection. Furthermore, this type of static disconnect device offers advantages in the case of high alternating current (AC) or for arc flash mitigation.

[0004] A switching device of the aforementioned type, also known as a solid-state circuit breaker, includes, in particular, a solid-state main switch, comprising, for example, at least one transistor, of the field-effect transistor (MOSFET) or JFET type, or of the insulated-gate bipolar transistor (IGBT) type. It also includes a disconnector, which performs the function of a main switch. Document WO2013092873 describes a device according to the preamble of claim 1.

[0005] We know of semiconductor switching devices configured to be controlled according to three states, which are respectively: a closed state, in English "ON", in which the switching device allows current to flow between the connection terminals between which it is connected; an open state, in English "OFF", in which the main switch and the disconnector are open, the electric current does not flow between the connection terminals; and a passive standby state, in English "STANDBY", in which the main switch is open but the disconnector is closed.

[0006] Semiconductor components must be protected against overvoltages, especially in the "ON" and "STANDBY" states of the switching device.

[0007] It is common practice to associate a varistor protection device with the main solid-state switch. This device, for example, is a varistor made of metal oxides, or MOV (for "Metal Oxide Varistor"), connected in parallel with the main solid-state switch and capable of withstanding very high energy, thus providing protection in the event of an electrical fault causing tripping. This type of protection device is effective in protecting against high, sudden overvoltages, for example, during switching (from the "ON" to the "OFF" state) or during the transition from the "ON" to the "STANDBY" state.When closing the disconnector, in the passive "STANDBY" state, it is also necessary to avoid damage to the varistor in the event of an overvoltage, in particular an overvoltage from the electrical distribution network to which the static switching device is connected.

[0008] In addition, it is also necessary to ensure the protection of the main solid-state switch when the switching device is in the "STANDBY" state, in the event of an excessive overvoltage.

[0009] To this end, the invention proposes, according to one aspect, an electrical circuit interruption device with overvoltage protection, comprising a pair of connection terminals, a main semiconductor switch(s) comprising at least one semiconductor component and a pair of separable contacts forming a disconnector connected in series with the main semiconductor switch(s) between the connection terminals.This electrical disconnection device comprises a first protection system connected in parallel with the main switch, the first protection system comprising a first protection device including a varistor and a first switch connected in series with the first protection device, and a second protection system, connected in parallel with said first protection system and said main semiconductor switch(s), the second protection system comprising a second protection device including a transient voltage suppression diode.

[0010] Advantageously, the proposed switching device includes two protection systems connected in parallel with the main solid-state switch, the first protection system comprising a varistor and the second protection circuit comprising a transient voltage suppression diode, which makes it possible to ensure complete protection of the main solid-state switch and the varistor against overvoltages, especially in the passive standby state.

[0011] The cutting device according to the invention may have one or more of the characteristics below, taken independently or according to all acceptable combinations.

[0012] The second protection system further includes a second switch connected in series with the second protection device.

[0013] The second switch of the second protection system is of the thyristor type, comprising two thyristors connected in parallel and in opposition.

[0014] The second switch of the second protection system includes at least one JFET field-effect transistor.

[0015] The device further includes an electronic controller connected to the main semiconductor switch(s) and a current measurement module flowing between the connection terminals, the electronic controller being configured to switch the main semiconductor switch(s) from a closed state to an open state when the current measured by the current measurement module exceeds a predetermined cut-off current threshold.

[0016] The electronic controller is further configured to control said first switch of the first protection system, and, when the second protection system further includes a second switch, said electronic controller is further configured to control said second switch.

[0017] The first switch of the first protection system comprises two thyristors connected in parallel and in opposition.

[0018] The main solid-state switch includes at least one insulated-gate field-effect or bipolar transistor.

[0019] According to another aspect, the invention relates to a method for breaking an electrical circuit, implemented by a breaking device as briefly described above, comprising, when the breaking device is in a closed state in which an electric current flows between the connection terminals: Upon receipt of a remote command or when the electric current flowing between the connection terminals exceeds a predetermined breaking current threshold, the main switch is switched from a closed state to an open state, inducing an electric current flow through the first protection system; then, when the electric current is below the predetermined breaking current threshold, the first switch of the first protection system is opened, and, if a second switch is present in the second protection system, the second switch is closed, the disconnecting device then being in a passive standby state.

[0020] According to one embodiment, the method comprises, starting from the passive standby state of the switching device, upon receipt of a remote command or a manual command to open the switching device, opening the disconnector, and, in the event of the presence of a second switch, opening the second switch, the switching device then being in an open state.

[0021] According to one embodiment, the method comprises, upon receipt of a manual or remote command to close the switching device, switching the switching device from the open state to the passive standby state by closing the disconnector and, if there is a second switch, closing the second switch, then, upon receipt of a command or automatically, switching the switching device from the passive standby state to the closed state, by closing the main switch and the first switch of the first protection system, and if there is a second switch, opening the second switch.

[0022] Other features and advantages of the invention will become apparent from the description given below, by way of example and not limitation, with reference to the attached figures, including: [ Fig 1 ] there figure 1 schematically represents a switching device according to a first embodiment; [ Fig 2 ] there figure 2 schematically represents a switching device according to a second embodiment; [ Fig 3 ] there figure 3 schematically represents an embodiment of a first switch and a second switch of the figure 2 ; Fig 4 ] there figure 4 schematically represents another embodiment of the second switch of the figure 2 ; Fig 5 ] ] Fig 6 ] ] Fig 7 ] THE figures 5 , 6 And 7 illustrate the states of the switches and the flow of electric current in various states of the switching device; [ FIG 8 ] there figure 8 is a flowchart of the first part of the circuit breaking process implemented by a circuit breaking device according to one embodiment, and [ FIG 9 ] there figure 9 is a flowchart of a second part of the circuit breaking process implemented by a circuit breaking device according to an embodiment.

[0023] There figure 1 represents an electrical circuit breaking device 2, comprising a pair of connection terminals 4, 6, these connection terminals being intended to be connected or linked each to an electrical conductor of an electrical circuit not shown.

[0024] For example, one of the connection terminals is connected to the electrical distribution network, and the other connection terminal is connected to an electrical load.

[0025] It is clear to those skilled in the art that a disconnecting device 2 represents a single connection point and can be adapted for a single-phase or multi-phase installation, for example, one with three phase conductors and one neutral conductor. The number of disconnecting devices per connection point 4, 6 is adjusted according to the number of phases.

[0026] The switching device 2 includes a main current conductor 8 between the connection terminals 4 and 6.

[0027] A main semiconductor switch(s) 10 is connected between a first connection point 15 and a second connection point 17 of the main conductor 8.

[0028] In the illustrated example, the main semiconductor switch 10 includes semiconductor components 12, 14, which here are two transistor switches 12, 14, connected in series in different directions, for example field-effect transistors, MOSFET or JFET, or insulated-gate bipolar type (IGBT), each transistor having an operating rating chosen according to the current, voltage and maximum permissible losses.

[0029] Of course, this main semiconductor switch 10 can, depending on the variants, include a different number of transistors, in parallel or in series.

[0030] The switching device 2 further includes a disconnector 16, which comprises two separable contacts 16a, 16b. This disconnector 16 can be actuated to change from an open state, in which the contacts 16a and 16b are separated, thus interrupting the flow of electric current between the connection point 17 and the terminal 6, to a closed state in which the contacts 16a, 16b are joined, and therefore allow an electric current to flow between the connection point 17 and the connection terminal 6. In other words, the disconnector 16 performs the function of a main switch.

[0031] The switching device 2 further includes an electronic controller 20, which is a programmable unit comprising a processor 23 and a memory 25, and which is adapted to execute code instructions.

[0032] The controller 20 is, alternatively, formed by a dedicated integrated circuit (in English, "Application-Specific Integrated Circuit"), by a set of programmable logic components, or by any set of electronic components.

[0033] The controller 20 is configured to communicate with a current measurement module 22, for example a current sensor 22 adapted to periodically measure (sample) current intensity values ​​in the main conductor 8, the controller 20 being configured to receive numerical values ​​of measured current intensity.

[0034] In addition, the controller 20 is configured to implement a current intensity monitoring process, and to control the opening or closing of the various switching or breaking elements of the breaking device 2.

[0035] The controller 20 is specifically configured to control the opening of the transistor switches of the main switch 10 when the measured current intensity exceeds a predetermined cut-off current threshold.

[0036] In addition, controller 20 is configured to control the opening of disconnector 16.

[0037] Optionally, the controller 20 includes a communication interface 27, for example a radio communication interface. In this case, the controller 20 is adapted to receive commands from an external device (not shown), for example a remote control, thus allowing remote control of the change of state of the switching device 2, in particular the change from the "ON" state to the "STANDBY" state and possibly vice versa, from the "STANDBY" state to the "OFF" state.

[0038] The switching device 2 also includes a first protection system 30 connected in parallel with the main switch 10 and a second protection system 40 connected in parallel with the main switch 10.

[0039] The first protection system 30 includes a varistor protection device 32, which includes, for example, a varistor composed of metal oxides, also called MOV (for "Metal Oxide Varistor" in English), connected in series with a first switch 34.

[0040] The first protection system 30 is connected in parallel with the main switch 10, between connection points 15 and 17. In other words, the first protection device 32 is connected between connection point 15 and an input of the first switch 34, and an output of the first switch 34 is connected to connection point 17.

[0041] In some embodiments, the varistor protection device 32 is voltage-calibrated so as not to exceed the avalanche voltage of the semiconductors 12, 14 with the maximum current obtained in case of a short circuit (typically 500V or 1000V if semiconductors 750V or 1.2kV for a current of 10 times the nominal current of the breaking device 2) or power-calibrated to tolerate the maximum power stored in the inductive elements of the circuit protected by the circuit breaker and which will have to be dissipated (typically 10 to 100 Joules).

[0042] The second protection system 40 includes, in the embodiment of the figure 1 , a 42 diode protection device for transient voltage suppression or TVS (for "Transient Voltage Suppression").

[0043] In some embodiments, the transient voltage suppression diode protection device 42 is calibrated in voltage, so as not to exceed the avalanche voltage of the semiconductors 12, 14 with the maximum current obtained in case of transient overvoltage of lightning type (typically 600V or 1100V if semiconductors 750V or 1.2kV for a current of 2 or 4 kA) or in power, to tolerate the current and voltage during a lightning type wave of a duration of about 50µs.

[0044] In a second embodiment, schematically illustrated at the figure 2 , the switching device 2 further comprises, in the second protection system 40, a second switch 44 connected in series with the transient voltage suppression diode protection device 42.

[0045] The second protection system 40 is connected in parallel with the main switch 10, between connection points 15 and 17. In other words, the protection device 42 is connected between connection point 15 and an input of the second switch 44, and an output of the second switch 44 is connected to connection point 17.

[0046] The first switch 34 and the second switch 44 are, for example, thyristor switches.

[0047] In one embodiment, the first switch 34 and the second switch 44 are both implemented in the form of a switch 50 with two opposing thyristors, according to the embodiment schematically illustrated in the figure 3 .

[0048] A thyristor switch 50 includes, in the embodiment of the figure 3 , a first thyristor 52 and a second thyristor 54, the first thyristor 52 being controlled by a control module 56 and the second thyristor 54 being controlled by a control module 58.

[0049] In the switching device 2, the control module 58 of each of the switches is controlled by the controller 20. In other words, the controller 20 is configured to control the state of the first switch 34, and of the second switch 44.

[0050] Advantageously, a 50 thyristor switch is inexpensive and robust.

[0051] Advantageously, a 50 thyristor switch automatically switches to open mode ("OFF") when the current intensity through it drops to zero.

[0052] According to one variant, the second switch 44 is a JFET field-effect transistor switch type, as schematically illustrated in the figure 4 .

[0053] Such a field-effect transistor switch, schematically represented at the figure 4 and referenced 60, comprises two field-effect transistors 62, 64 and a control module 66.

[0054] In the switching device 2, when the second switch 44 is of the type shown in the figure 4 The control module 66 is controlled by the controller 20. In other words, the controller 20 is configured to control the state of the second switch 44.

[0055] Advantageously, such a 60 switch is closed at rest, which helps to protect the semiconductors.

[0056] Preferably, the cut-off device 2 is integrated into a dedicated housing.

[0057] THE figures 5 , 6 And 7 illustrate the operation of the first and second protection systems, according to various states of the cutting device 2.

[0058] The switching device 2 is shown in the "ON" state at the figure 5 .

[0059] In nominal operation, when the electric current flowing through the main conductor 8 is below a breaking current threshold, the switching device 2 is in the "ON" state, the disconnector 16 is closed, the first switch 34 is closed, and, in the embodiment in which it is present, the second switch 44 is open. The solid-state main switch 10 is in the closed state.

[0060] Thus, the electric current flows between the connection terminal 4 and the connection terminal 6 via the main switch 10 (transistors 12 and 14 closed), and the disconnector 16. The flow of the electric current is shown schematically by the arrow F.

[0061] Advantageously, the first switch 34 is closed so that the first protection system 30 is operational.

[0062] In the event of exceeding the breaking current threshold, or upon remote command received by the controller 20, the breaking device switches from the "ON" state to the "STANDBY" state.

[0063] In the event of a tripping, when the current exceeds the breaking current threshold, the first protection system 30 is activated. The electric current then passes through the varistor protection device 32, which is designed to limit the voltage. The main switch 10 opens, the disconnector 16 closes, the first switch 34 closes, and the second switch 44 opens. The flow of electric current is shown schematically by arrow F' in the diagram. figure 6 .

[0064] The switching device 2 is in passive standby or “STANDBY” state when, following a remote command or after overvoltage limitation in the event of tripping of the switch by disjunction, the intensity of the electric current is less than the switching current threshold.

[0065] In this state, the main switch 10 is open, the disconnector 16 is closed.

[0066] The controller 20 advantageously controls the opening of the first switch 34 of the first protection system and the closing of the second switch 44 of the second protection system.

[0067] Preferably, the opening of the first switch 34 of the first protection system and the closing of the second switch 44 of the second protection system are carried out simultaneously or substantially simultaneously.

[0068] Advantageously, the varistor protection device 32 of the first protection system 30 is protected, the current no longer flowing in this first protection system 30, and, in the event of an overvoltage occurring, for example a high point overvoltage or a moderate overvoltage of the distribution network, for a given duration, for example an overvoltage of 20% for a duration of about one minute the second protection system 40 is used.

[0069] The current flow is schematically represented by arrow F" in the figure 7 .

[0070] On this figure 7 In addition, the voltage Vs applied during an overvoltage of the electrical distribution network (for example 4kV) and the impedance Zs of this source are schematically represented.

[0071] When the switching device 2 is in the "OFF" (open) state, on remote control or via a manual control applied directly to a control element present on the front of a box encapsulating the switching device, the main switch 10, the disconnector 16, as well as the first switch 34 and the second switch 44 are open.

[0072] There figure 8 is a synoptic diagram of the main steps in the first part of the electrical circuit breaking process implemented by a breaking device 2, and the figure 9 is a synoptic of the main steps of a second part of the electrical circuit breaking process implemented by a breaking device 2.

[0073] In one embodiment, the steps of the process are implemented by the controller 20 of the switching device 2.

[0074] Starting from a closed state (“ON”), referenced E1 on the figure 8 , of the breaking device 2, in which an electric current flows between the connection terminals 4 and 6 in nominal operation, the method includes monitoring 70 for a possible exceedance of the breaking current threshold, consisting of comparing the electric current I flowing in the conductor to the breaking threshold Ic, as well as monitoring 72 for the reception of a remote command to open the breaking device 2.

[0075] When monitoring 70 of exceeding the breaking current threshold or monitoring 72 provides a positive response, the method includes switching 74 of the main switch 10 from the closed state to the open state, inducing an electric current flow through the first protection system 30.

[0076] The passage of the electric current below the breaking current threshold is monitored (step 76), and when the electric current is below the predetermined breaking current threshold, the method includes a command 78 to open the first switch 34 of the first protection system 30. In the embodiment where the second protection system 40 includes a second switch 44, the method further includes a command 80 to close the second switch 44.

[0077] Steps 78 and 80 are carried out simultaneously or almost simultaneously.

[0078] Following these steps, the switching device 2 is in the passive standby state ("STANDBY") reference E2 on the figure 8 .

[0079] The process then includes a check 82 for receipt of the command to open the switching device, this command being able to be manual or remote, and in the event of a positive check, an opening 84 of the disconnector 16, and, in the event of the presence of a second switch 44, an opening 86 of the second switch 44, the switching device 2 then being in an open state (“OFF”) referenced E3 on the figure 8 .

[0080] In a second part (meaning "return"), illustrated in the figure 9 The process includes a check 88 of receipt of the closing command of the switching device, this command being able to be manual or remote, and in the event of a positive check, in the event of the presence of a second switch 44, a closing command 90 of the second switch 44 and a closing command 92 of the disconnector 16. In other words, steps 90 and 92 correspond respectively to the inverse actions of steps 86 and 84.

[0081] The switching device 2 thus transitions from the open state to the passive standby state E2.

[0082] Then, upon receipt of a command or automatically (step 94), the process includes a command 96 to close the first switch 34 of the first protection system, and in the event of the presence of a second switch 44, a command 98 to open the second switch 44.

[0083] In other words, steps 96 and 98 correspond respectively to the inverse actions of steps 78 and 80.

[0084] The process also includes a step 100 of closing the main switch 10, the reverse of the action of step 74.

[0085] The switching device 2 is then in the closed state E1, and where applicable, the first part of the process described with reference to the figure 8 applies.

[0086] Advantageously, the switching device 2 is protected against overvoltage by the first and second protection systems, in both the "ON" and "STANDBY" operating states. Thus, thanks to the additional presence of the disconnector, the switching device is protected against overvoltage in all its operating states.

Claims

1. An electrical circuit-breaking device with overvoltage protection, comprising a pair of connection terminals (4,6), a semiconductor(s) main switch (10) comprising at least one semiconductor component (12, 14) and a pair of separable contacts (16a, 16b) forming a disconnector (16) connected in series with the semiconductor(s) main switch (10) between the connection terminals (4, 6), the electrical switching device (2) comprising a first protection system (30) connected in parallel with the main switch (10), the first protection system (30) comprising a first protection device (32) comprising a varistor, characterised in that the first protection system further comprises a first switch (34) connected in series with the first protection device (32), and a second protection system (40), connected in parallel with the said first protection system (30) and the said main semi-conductor switch (10), the second protection system (40) comprising a second protection device (42) comprising a diode for suppressing transient voltages.

2. A device according to claim 1, wherein the second protection system (40) further comprises a second switch (44) connected in series with the second protection device (42).

3. Device according to claim 2, in which the second switch (44) of the second protection system (40) is of the thyristor type, comprising two thyristors (52, 54) connected in parallel and in opposition4. A device according to claim 2, wherein the second switch (44) of the second protection system (40) comprises at least one JFET (62, 64).

5. A device according to any one of claims 1 to 4, further comprising an electronic controller (20) connected to the semiconductor(s) main switch (10) and a current measurement module (22) flowing between the connection terminals (4,6), the electronic controller (20) being configured to switch the semiconductor(s) main switch (10) from a closed state to an open state when the current measured by the current measurement module (22) exceeds a predetermined cut-off current threshold.

6. A device according to claim 5, wherein the electronic controller (20) is further configured to control said first switch (34) of the first protection system (30), and, when the second protection system (40) further comprises a second switch (44), said electronic controller (20) is further configured to control said second switch (44).

7. A device according to any one of claims 1 to 6, wherein the first switch (34) of the first protection system comprises two thyristors (52, 54) connected in parallel and in opposition.

8. A device according to any one of claims 1 to 7, wherein said semiconductor main switch (10) comprises at least one insulated gate field effect or bipolar transistor.

9. Process for breaking an electrical circuit, implemented by a breaking device (2) according to one of claims 1 to 8, comprising, when the breaking device is in a closed state (E1) in which an electrical current flows between the connection terminals (4,6), - on receiving (72) a remote command or when said electric current flowing between the connection terminals (4, 6) exceeds (70) a predefined cut-off current threshold, switching (74) of the main switch (10) from a closed state to an open state, inducing a flow of electric current through the first protection system (30), - then, when the electrical current is less than the predetermined cut-off current threshold, command (78) to open the first switch (34) of the first protection system (30), and, if a second switch (44) is present in the second protection system (40), command to close (80) said second switch (44), the cut-off device (2) then being in a passive standby state (E2).

10. A method according to claim 9, comprising, starting from the passive standby state of the switching device (2), on receipt (82) of a remote command or a manual command to open the switching device (2), opening (84) of the disconnector (16), and, if a second switch (44) is present, opening (86) of the second switch (44), the switching device (2) then being in an open state (E3).

11. A method according to claim 10, comprising, on receiving (88) a manual command or a remote command to close the switching device (2), switching the switching device (2) from the open state to the passive standby state by closing (92) the isolating switch (16) and, if a second switch (44) is present, closing (90) the second switch (44), then, on receiving a command or automatically (94), the switching device (2) changes from the passive standby state to the closed state, by command (96, 100) to close the main switch (10) and the first switch (34) of the first protection system, and if a second switch (44) is present, command (98) to open the second switch (44).