Multi-port Hybrid DC Circuit Breaker and Its Control Method

Abstract

The present application provides a multi-port hybrid DC circuit breaker and its control method. The multi-port hybrid DC circuit breaker includes at least two current-carrying branches, at least two commutation branches and a breaking branch. The current-carrying branch includes a first fast mechanical switch and a unidirectional commutation switch connected in series. One ends of the current-carrying branches are connected to each other to form a DC bus; the commutation branch includes a diode upper arm and a diode lower arm connected in series in the same direction. The other end of each current-carrying branch is correspondingly connected to the midpoint of each commutation branch to form a port; the breaking branch includes a unidirectional breaking switch and a non-linear resistor connected in parallel. The breaking branch and the commutation branch are connected in parallel to form a first common bus and a second common bus.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and particularly to a multi-port hybrid DC circuit breaker and its control method. Background Art

[0002] With the complexity of the future DC power grid network structure, the number of DC circuit breakers to be installed in the system will increase significantly. Since the investment cost of DC circuit breakers is too high, it has become a bottleneck problem restricting the development of DC power grids. Considering that the breaking switch composed of a large number of power electronic devices in series and parallel is the main cost of DC circuit breakers, in recent years, the design concept of multi-port DC circuit breakers has been proposed, that is, all incoming and outgoing lines on the same DC bus share the expensive breaking switch. Therefore, the use of multi-port DC circuit breakers can ensure the breaking ability of the fault current of each incoming and outgoing line while significantly reducing the number and investment cost of DC circuit breakers in the DC power grid.

[0003] Patent CN110048377A and the paper "Zhang S, Zou G, Wei X, etal. Diode-bridgemulti-port hybrid DC circuit breaker for multi-terminal DC grids[J]. IEEETransactions on Industrial Electronics,2021, 68(1): 270-281." proposed a new type of multi-port DC circuit breaker and its control method applicable to DC distribution networks, which can realize normal line switching on and off, isolate faulty lines or buses, and has the ability to protect against fast mechanical switch failures. However, the number of semiconductors in the current flow path of this multi-port DC circuit breaker is relatively large, and the on-current loss is relatively high. In addition, the bus fault protection only considers DC bus faults and does not consider the faults of the two common buses inside the multi-port DC circuit breaker. Summary of the Invention

[0004] The embodiment of the present application provides a multi-port hybrid DC circuit breaker, which includes at least two current-carrying branches, at least two commutation branches and a breaking branch. The current-carrying branch includes a first fast mechanical switch and a unidirectional commutation switch connected in series. One ends of the current-carrying branches are connected to each other to form a DC bus, and the breaking current directions of the unidirectional commutation switches of each current-carrying branch are the same; the commutation branch includes a diode upper arm and a diode lower arm connected in series in the same direction. The other end of each current-carrying branch is correspondingly connected to the midpoint of each commutation branch to form a port; the breaking branch includes a unidirectional breaking switch and a non-linear resistor connected in parallel. The breaking branch and the commutation branch are connected in parallel to form a first common bus and a second common bus. The breaking current direction of the unidirectional breaking switch of the breaking branch is from the first common bus to the second common bus. The cathode of the diode upper arm of the commutation branch is connected to the first common bus, and the anode of the diode lower arm of the commutation branch is connected to the second common bus.

[0005] According to some embodiments, the multi-port hybrid DC circuit breaker further includes a bus fault protection branch, and the bus fault protection branch includes a second fast mechanical switch. When the multi-port hybrid DC circuit breaker is installed at the positive pole of the DC system, one end of the bus fault protection branch is connected to the DC bus, and the other end is connected to the first common bus; when the multi-port hybrid DC circuit breaker is installed at the negative pole of the DC system, one end of the bus fault protection branch is connected to the DC bus, and the other end is connected to the second common bus.

[0006] According to some embodiments, the multi-port hybrid DC circuit breaker further includes a bus fault protection branch, and the bus fault protection branch includes a second fast mechanical switch and a unidirectional conduction switch connected in series. Both ends of the bus fault protection branch are respectively connected to the first common bus and the second common bus, and the midpoint of the bus fault protection branch is connected to the DC bus; when the multi-port hybrid DC circuit breaker is installed at the positive pole of the DC system, the second fast mechanical switch is connected to the first common bus, the unidirectional conduction switch is connected to the second common bus, and the conduction direction of the unidirectional conduction switch is from the second common bus to the DC bus, and the breaking current direction of the unidirectional commutation switch of the current-carrying branch points to the DC bus; when the multi-port hybrid DC circuit breaker is installed at the negative pole of the DC system, the second fast mechanical switch is connected to the second common bus, the unidirectional conduction switch is connected to the first common bus, and the conduction direction of the unidirectional conduction switch is from the DC bus to the first common bus, and the breaking current direction of the unidirectional commutation switch of the current-carrying branch points to the port.

[0007] According to some embodiments, the multi-port hybrid DC circuit breaker further includes an auxiliary energy-consuming branch, and the auxiliary energy-consuming branch includes a diode and a linear resistor connected in series; when the multi-port hybrid DC circuit breaker is installed at the positive pole of the DC system, one end of the auxiliary energy-consuming branch is connected to the second common bus, the other end of the auxiliary energy-consuming branch is connected to the ground or the metal return line, and the cathode of the diode points to the second common bus; when the multi-port hybrid DC circuit breaker is installed at the negative pole of the DC system, one end of the auxiliary energy-consuming branch is connected to the first common bus, the other end of the auxiliary energy-consuming branch is connected to the ground or the metal return line, and the anode of the diode points to the first common bus.

[0008] According to some embodiments, the first fast mechanical switch or the second fast mechanical switch includes at least one mechanical switch break connected in series, the diode includes at least one diode connected in series, the unidirectional commutation switch includes at least one first switch semiconductor device connected in series, the unidirectional breaking switch includes at least one first switch semiconductor device connected in series, the unidirectional conducting switch includes at least one diode connected in series and at least one second switch semiconductor device connected in series, and the diode and the second switch semiconductor device are connected in series with each other; the first switch semiconductor device includes at least one of IGBT, IEGT, IGCT, MOSFET; the second switch semiconductor device includes at least one of SCR, IGBT, IEGT, IGCT, MOSFET.

[0009] The embodiment of the present application further provides a control method for the multi-port hybrid DC circuit breaker as described above, including controlling the on / off of the current-carrying branch, the commutation branch, and the breaking branch based on the working mode of the multi-port hybrid DC circuit breaker, and the working mode includes a normal operation mode, a tripping mode, and a closing mode.

[0010] According to some embodiments, when the multi-port hybrid DC circuit breaker is in the normal operation mode, each current-carrying branch is in the conducting state, the breaking branch is in the off state, and when the multi-port hybrid DC circuit breaker includes a bus fault protection branch, the bus fault protection branch is in the off state.

[0011] According to some embodiments, when the multi-port hybrid DC circuit breaker is in the open mode and any of the ports connected to the multi-port hybrid DC circuit breaker needs to be disconnected, the following steps are included: controlling the unidirectional disconnection switch of the disconnection branch to conduct and the unidirectional commutation switches of all current-carrying branches to turn off, so that the current starts to transfer to the unidirectional disconnection switch of the disconnection branch through the commutation branch; when the currents of all current-carrying branches approach zero, controlling the fast mechanical switch of the current-carrying branch where the port to be disconnected is located to open; when the fast mechanical switch of the current-carrying branch where the port to be disconnected is located is separated to the insulation voltage position, controlling the unidirectional disconnection switch of the disconnection branch to turn off and the unidirectional commutation switches of all current-carrying branches to conduct, the current of the port to be disconnected transfers to the non-linear resistor of the disconnection branch and the linear resistor of the auxiliary energy-consuming branch and gradually drops to zero, and the currents of other ports except the port to be disconnected return to their respective current-carrying branches, and the opening is successful and the opening operation ends.

[0012] According to some embodiments, when the multi-port hybrid DC circuit breaker is in the closed mode and any port connected to the multi-port hybrid DC circuit breaker needs to be connected, the following steps are included: controlling the unidirectional disconnection switch of the disconnection branch to conduct; if the multi-port hybrid DC circuit breaker is not closed on a fault, controlling the fast mechanical switch of the current-carrying branch where the port to be connected is located to close; if the multi-port hybrid DC circuit breaker is closed on a fault, controlling the unidirectional disconnection switch of the disconnection branch to turn off, and the closing fails and the closing operation ends; after the fast mechanical switch of the current-carrying branch where the port to be connected is located is in the closed position, controlling the unidirectional disconnection switch of the disconnection branch to turn off, and the closing is successful and the closing operation ends.

[0013] According to some embodiments, when the multi-port hybrid DC circuit breaker includes a bus fault protection branch, the operating mode further includes a bus fault protection mode. When the multi-port hybrid DC circuit breaker is in the bus fault protection mode, it is controlled based on the fault type. Among them, when the fault type is a DC bus grounding fault, the unidirectional breaking switch of the breaking branch is controlled to conduct, the unidirectional conducting switch of the bus fault protection branch is controlled to conduct, and the unidirectional commutation switches of all current-carrying branches are controlled to turn off. The current starts to transfer through the commutation branch to the unidirectional breaking switch of the breaking branch. When the current in all current-carrying branches approaches zero, the fast mechanical switches of all current-carrying branches are controlled to trip. When the fast mechanical switches of all current-carrying branches are separated to the insulation voltage position, the unidirectional breaking switch of the breaking branch is controlled to turn off, and the unidirectional commutation switches of all current-carrying branches are controlled to conduct. The current transfers to the non-linear resistor of the breaking branch and drops to zero, and the tripping is successful and the tripping operation ends. When the fault type is that the multi-port hybrid DC circuit breaker is installed at the positive pole of the DC system and the first common bus has a grounding fault, the multi-port hybrid DC circuit breaker cannot complete the bus isolation operation, and the failure backup protection is started and the fast mechanical switch of the bus fault protection branch is controlled to close. When the fault type is that the multi-port hybrid DC circuit breaker is installed at the negative pole of the DC system and the second common bus has a grounding fault, the multi-port hybrid DC circuit breaker cannot complete the bus isolation operation, and the failure backup protection is started and the fast mechanical switch of the bus fault protection branch is controlled to close. When the fault type is that the multi-port hybrid DC circuit breaker is installed at the positive pole of the DC system and the second common bus has a grounding fault, the bus differential protection will not operate in the normal operation mode of the multi-port hybrid DC circuit breaker. If the tripping operation is performed at this time, the bus differential protection will operate, and the multi-port hybrid DC circuit breaker aborts the tripping operation and starts the backup failure protection. When the fault type is that the multi-port hybrid DC circuit breaker is installed at the negative pole of the DC system and the first common bus has a grounding fault, the bus differential protection will not operate in the normal operation mode of the multi-port hybrid DC circuit breaker. If the tripping operation is performed at this time, the bus differential protection will operate, and the multi-port hybrid DC circuit breaker aborts the tripping operation and starts the backup failure protection.

[0014] The technical solution provided by the embodiments of the present application can achieve the fault protection of multiple transmission lines by sharing expensive breaking switches. The more transmission lines there are, the better the economy. Compared with the existing two-port or multi-port hybrid DC circuit breakers, the number of semiconductors through which the current flows is halved, the current-carrying loss is lower, and the economy is better. It has the ability to protect against bus faults, improving the reliability of the DC circuit breaker. It has the ability of auxiliary energy consumption, and the auxiliary energy consumption is carried out through highly reliable linear resistors, thereby reducing the demand for the energy of the non-linear resistor and improving the reliability of the DC circuit breaker. It maintains the fast breaking of the rated current, the fast breaking of the fault current, and the fast reclosing of the hybrid DC circuit breaker. Description of the Drawings

[0015] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0016] Figure 1 is the topological diagram of the first embodiment of a multi-port hybrid DC circuit breaker in the embodiments of the present application.

[0017] Figure 2 is the topological diagram of the second embodiment of a multi-port hybrid DC circuit breaker when installed at the positive pole of the DC system.

[0018] Figure 3 is the topological diagram of the second embodiment of a multi-port hybrid DC circuit breaker when installed at the negative pole of the DC system.

[0019] Figure 4 is the topological diagram of the third embodiment of a multi-port hybrid DC circuit breaker when installed at the positive pole of the DC system.

[0020] Figure 5 is the topological diagram of the third embodiment of a multi-port hybrid DC circuit breaker when installed at the negative pole of the DC system.

[0021] Figure 6 is the topological diagram of the fourth embodiment of a multi-port hybrid DC circuit breaker when installed at the positive pole of the DC system.

[0022] Figure 7 is the topological diagram of the fourth embodiment of a multi-port hybrid DC circuit breaker when installed at the negative pole of the DC system.

[0023] Figure 8 is the topological diagram of the fifth embodiment of a multi-port hybrid DC circuit breaker when installed at the positive pole of the DC system.

[0024] Figure 9 is the topological diagram of the fifth embodiment of a multi-port hybrid DC circuit breaker when installed at the negative pole of the DC system.

[0025] Figure 10 is the topological diagram of the sixth embodiment of a multi-port hybrid DC circuit breaker when installed at the positive pole of the DC system.

[0026] Figure 11It is the topology diagram of the sixth embodiment of a multi-port hybrid DC circuit breaker when installed at the negative pole of the DC system.

[0027] Figure 12 It is a schematic diagram of the breaking switch of a multi-port hybrid DC circuit breaker according to an embodiment of the present application. Specific embodiments

[0028] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0029] It should be understood that the terms "including" and "comprising" used in the specification and claims of the present application indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0030] Figure 1 It is the topology diagram of the first embodiment of a multi-port hybrid DC circuit breaker according to an embodiment of the present application.

[0031] As Figure 1 shown, the multi-port hybrid DC circuit breaker includes n current-carrying branches (101,..., 10k,..., 10n), n commutation branches (201,..., 20k,..., 20n), and 1 breaking branch (300), where n is the number of ports and k represents the kth branch.

[0032] Each current-carrying branch (10k) includes a first fast mechanical switch (11k) and a unidirectional commutation switch (12k) connected in series. Each commutation branch (20k) includes a diode upper arm (21k) and a diode lower arm (22k) connected in series in the same direction. The current-carrying branches (10k) and the commutation branches (20k) correspond one by one. One ends of all the current-carrying branches (101-10n) are connected to each other to form a DC bus, and the other end of each current-carrying branch (10k) is connected to the midpoint of the commutation branch (20k) to form a port (Pk), and this port is connected to the equipment or line to be protected. The breaking branch (300) includes a unidirectional breaking switch (310) and a non-linear resistor (320) connected in parallel.

[0033] The breaking branch (300) and all commutation branches (201 - 20n) are connected in parallel with each other and form a first common bus and a second common bus. The breaking current direction of the unidirectional breaking switch (310) of the breaking branch (300) is from the first common bus to the second common bus, that is, it can break the current flowing from the first common bus to the second common bus. The cathodes of the diode upper bridge arms (211 - 21n) of the commutation branches (201 - 20n) are connected to the first common bus, and the anodes of the diode lower bridge arms (221 - 22n) of the commutation branches (201 - 20n) are connected to the second common bus. The breaking current directions of the unidirectional commutation switches (121 - 12n) of each current-carrying branch (101 - 10n) are the same, that is, all point to the DC bus or all point to the port.

[0034] The multi-port hybrid DC circuit breaker of this embodiment can be applied in the occasion without considering DC bus faults. The working modes of the multi-port hybrid DC circuit breaker include: normal operation mode, opening mode, and closing mode.

[0035] In the normal operation mode of the multi-port hybrid DC circuit breaker, the fast mechanical switches (111 - 11n) and the unidirectional commutation switches (121 - 12n) of each current-carrying branch (101 - 10n) are all in the conducting state, and the unidirectional breaking switch (310) of the breaking branch (300) is in the off state.

[0036] In the opening mode of the multi-port hybrid DC circuit breaker, when the P k th port connected to the multi-port hybrid DC circuit breaker needs to be disconnected, the operation process is as follows.

[0037] The first step: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct, and the unidirectional commutation switches (121 - 12n) of all current-carrying branches (101 - 10n) to turn off. The current starts to transfer through the commutation branches (201 - 20n) to the unidirectional breaking switch (310) of the breaking branch (300).

[0038] The second step: When the current of all current-carrying branches (101 - 10n) is close to zero, control the fast mechanical switch (11k) of the current-carrying branch (10k) of the Pkth port to open.

[0039] The third step: When the fast mechanical switch (11k) of the current-carrying branch (10k) of the P k th port is separated to the insulation voltage position, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, and the unidirectional commutation switches (121 - 12n) of all current-carrying branches to conduct. The current of the P k th port transfers to the non-linear resistor (320) of the breaking branch (300) and gradually drops to zero. For non-P kThe current of the ports returns to their respective current-carrying branches, the opening is successful and the opening operation ends.

[0040] In the closing mode of the multi-port hybrid DC circuit breaker, when the Pth k port to be connected by the multi-port hybrid DC circuit breaker is required to be connected, the operation process is as follows.

[0041] The first step: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct.

[0042] The second step: If the multi-port hybrid DC circuit breaker is not closed on a fault, control the fast mechanical switch (11k) of the Pth k port current-carrying branch (10k) to close; if the multi-port hybrid DC circuit breaker is closed on a fault, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, the closing fails and the closing operation ends.

[0043] The third step: When the fast mechanical switch (11k) of the Pth k port current-carrying branch (10k) is in the closed position, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, the closing is successful and the closing operation ends.

[0044] Figure 2 It is the topology diagram of the second embodiment of the multi-port hybrid DC circuit breaker when installed at the positive pole of the DC system in the embodiment of the present application. Compared with Figure 1 the multi-port hybrid DC circuit breaker shown, a bus fault protection branch (400) is added in this embodiment.

[0045] The bus fault protection branch (400) includes a second fast mechanical switch (410). One end of the second fast mechanical switch (410) is connected to the DC bus, and the other end is connected to the first common bus.

[0046] The working modes of the multi-port hybrid DC circuit breaker in this embodiment include a normal operation mode, an opening mode, a closing mode, and a bus fault protection mode.

[0047] In the normal operation mode of the multi-port hybrid DC circuit breaker, the fast mechanical switches (111-11n) and the unidirectional commutation switches (121-12n) of each current-carrying branch (101-10n) are in the conducting state, the unidirectional breaking switch (310) of the breaking branch (300) is in the off state, and the second fast mechanical switches (410) of the bus fault protection branch (400) are in the off state.

[0048] In the opening mode of the multi-port hybrid DC circuit breaker, when the Pth k port connected by the multi-port hybrid DC circuit breaker needs to be disconnected, the operation process is as follows.

[0049] Step 1: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct, and turn off the unidirectional commutation switches (121 - 12n) of all current-carrying branches (101 - 10n). The current starts to transfer through the commutation branches (201 - 20n) to the unidirectional breaking switch (310) of the breaking branch (300).

[0050] Step 2: When the current in all current-carrying branches (101 - 10n) approaches zero, control the fast mechanical switch (11k) of the current-carrying branch (10k) at the P k th port to trip.

[0051] Step 3: When the fast mechanical switch (11k) of the current-carrying branch (10k) at the P k th port is separated to the insulation voltage position, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, and turn on the unidirectional commutation switches (121 - 12n) of all current-carrying branches. The current at the P k th port transfers to the non-linear resistor (320) of the breaking branch (300) and gradually drops to zero, and the current at non-Pk ports resumes to their respective current-carrying branches. The tripping is successful and the tripping operation ends.

[0052] In the closing mode of the multi-port hybrid DC circuit breaker, when the P k th port connected to the multi-port hybrid DC circuit breaker needs to be connected, the operation process is as follows.

[0053] Step 1: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct;

[0054] Step 2: If the multi-port hybrid DC circuit breaker is not closed on a fault, control the fast mechanical switch (11k) of the current-carrying branch (10k) at the P k th port to close; if the multi-port hybrid DC circuit breaker is closed on a fault, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, the closing fails and the closing operation ends.

[0055] Step 3: When the fast mechanical switch (11k) of the current-carrying branch (10k) at the P k th port is in the closed position, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, the closing is successful and the closing operation ends.

[0056] In the bus fault protection mode of the multi-port hybrid DC circuit breaker, when a ground fault occurs on the DC bus or the first common bus or the second common bus, the DC circuit breaker cannot complete the bus isolation operation, and the failure backup protection will be started and the second fast mechanical switch (410) of the bus fault protection branch (400) will be controlled to close.

[0057] Figure 3 This is the topological diagram of the second embodiment of a multi-port hybrid DC circuit breaker when installed at the negative pole of a DC system. Compared with Figure 1 the embodiment shown, this embodiment adds a bus fault protection branch (400).

[0058] The bus fault protection branch (400) includes a second fast mechanical switch (410). One end of the second fast mechanical switch (410) is connected to the DC bus, and the other end is connected to the second common bus.

[0059] The operating modes of the multi-port hybrid DC circuit breaker in this embodiment include: normal operation mode, opening mode, closing mode, and bus fault protection mode.

[0060] In the normal operation mode of the multi-port hybrid DC circuit breaker, the first fast mechanical switches (111 - 11n) and the unidirectional commutation switches (121 - 12n) of each current-carrying branch (101 - 10n) are in the conducting state, the unidirectional breaking switch (310) of the breaking branch (300) is in the off state, and the second fast mechanical switches (410) of the bus fault protection branch (400) are in the off state.

[0061] In the opening mode of the multi-port hybrid DC circuit breaker, when the P k th port connected to the multi-port hybrid DC circuit breaker needs to be disconnected, the operation process is as follows.

[0062] Step 1: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct, and the unidirectional commutation switches (121 - 12n) of all current-carrying branches (101 - 10n) to turn off. The current starts to transfer through the commutation branches (201 - 20n) to the unidirectional breaking switch (310) of the breaking branch (300).

[0063] Step 2: When the current in all current-carrying branches (101 - 10n) approaches zero, control the first fast mechanical switch (11k) of the current-carrying branch (10k) of the P k th port to open.

[0064] Step 3: When the first fast mechanical switch (11k) of the current-carrying branch (10k) of the P k th port is separated to the insulation voltage position, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, and the unidirectional commutation switches (121 - 12n) of all current-carrying branches to conduct. The current of the P k th port transfers to the non-linear resistor (320) of the breaking branch (300) and gradually decreases to zero, and the current of the non-P k th port resumes to its respective current-carrying branch. The opening is successful and the opening operation ends.

[0065] In the closing mode of the multi-port hybrid DC circuit breaker, when the P-th k port connected to the multi-port hybrid DC circuit breaker needs to be connected, the operation process is as follows.

[0066] Step 1: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct.

[0067] Step 2: If the multi-port hybrid DC circuit breaker is not closed on a fault, control the first fast mechanical switch (11k) of the P-th k port current-carrying branch (10k) to close; if the multi-port hybrid DC circuit breaker is closed on a fault, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, the closing fails and the closing operation ends.

[0068] Step 3: After the first fast mechanical switch (11k) of the P-th k port current-carrying branch (10k) is in the closed position, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, the closing is successful and the closing operation ends.

[0069] In the bus fault protection mode of the multi-port hybrid DC circuit breaker, when a grounding fault occurs in the DC bus or the first common bus or the second common bus, the DC circuit breaker cannot complete the bus isolation operation, and the failure backup protection will be started and the second fast mechanical switch (410) of the bus fault protection branch (400) will be controlled to close.

[0070] Figure 4 It is the topological diagram of the third embodiment of the multi-port hybrid DC circuit breaker when installed at the positive pole of the DC system in the embodiments of the present application. Compared with Figure 1 the embodiment, this embodiment adds a bus fault protection branch (400).

[0071] The bus fault protection branch (400) includes a second fast mechanical switch (410) and a unidirectional conduction switch (420) connected in series. The second fast mechanical switch (410) is connected to the first common bus, the unidirectional conduction switch (420) is connected to the second common bus, the midpoint of the bus fault protection branch (400) is connected to the DC bus, and the conduction direction of the unidirectional conduction switch (420) is from the second common bus to the DC bus. In addition, the breaking current direction of the unidirectional commutation switches (121-12n) of the current-carrying branches (101-10n) points to the DC bus.

[0072] The working modes of the multi-port hybrid DC circuit breaker in this embodiment include normal operation mode, opening mode, closing mode, and bus fault protection mode.

[0073] In the normal operation mode of the multi-port hybrid DC circuit breaker, the first fast mechanical switches (111 - 11n) and the unidirectional commutation switches (121 - 12n) of each current-carrying branch (101 - 10n) are in the conducting state, the unidirectional breaking switch (310) of the breaking branch (300) is in the off state, and the second fast mechanical switch (410) and the unidirectional conducting switch (420) of the bus fault protection branch (400) are in the off state.

[0074] In the tripping mode of the multi-port hybrid DC circuit breaker, when the Pth k port connected to the multi-port hybrid DC circuit breaker needs to be disconnected, the operation process is as follows.

[0075] First step: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct, and turn off the unidirectional commutation switches (121 - 12n) of all current-carrying branches (101 - 10n). The current starts to transfer through the commutation branches (201 - 20n) to the unidirectional breaking switch (310) of the breaking branch (300).

[0076] Second step: When the current in all current-carrying branches (101 - 10n) approaches zero, control the first fast mechanical switch (11k) of the current-carrying branch (10k) of the Pth k port to trip.

[0077] Third step: When the first fast mechanical switch (11k) of the current-carrying branch (10k) of the Pth k port is separated to the insulation voltage position, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, and turn on the unidirectional commutation switches (121 - 12n) of all current-carrying branches. The current of the Pth k port transfers into the non-linear resistor (320) of the breaking branch (300) and gradually decreases to zero, and the current of the non-Pth k port resumes to its respective current-carrying branch. The tripping is successful and the tripping operation ends.

[0078] In the closing mode of the multi-port hybrid DC circuit breaker, when the Pth k port connected to the multi-port hybrid DC circuit breaker needs to be connected, the operation process is as follows.

[0079] First step: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct;

[0080] Second step: If the multi-port hybrid DC circuit breaker is not closed onto a fault, then control the Pth kThe first fast mechanical switch (11k) of the port current-carrying branch (10k) closes; if the multi-port hybrid DC circuit breaker closes onto a fault, then the unidirectional breaking switch (310) of the control breaking branch (300) turns off, the closing fails, and the closing operation ends.

[0081] The third step: When the k After the fast mechanical switch (11k) of the port current-carrying branch (10k) is in the closed position, the unidirectional breaking switch (310) of the control breaking branch (300) turns off, the closing is successful, and the closing operation ends.

[0082] In the bus fault protection mode of the multi-port hybrid DC circuit breaker, when a DC bus ground fault occurs, the operation process is as follows.

[0083] The first step: The unidirectional breaking switch (310) of the control breaking branch (300) conducts, the unidirectional conducting switch (420) of the bus fault protection branch (400) conducts, and the unidirectional commutation switches (121 - 12n) of all current-carrying branches (101 - 10n) turn off. The current starts to transfer through the commutation branches (201 - 20n) to the unidirectional breaking switch (310) of the control breaking branch (300).

[0084] The second step: When the current in all current-carrying branches (101 - 10n) approaches zero, control the first fast mechanical switches (111 - 11n) of all current-carrying branches (101 - 10n) to trip.

[0085] The third step: When the first fast mechanical switches (111 - 11n) of all current-carrying branches (101 - 10n) are separated to the insulation voltage position, control the unidirectional breaking switch (310) of the control breaking branch (300) to turn off and the unidirectional commutation switches (121 - 12n) of all current-carrying branches (101 - 10n) to conduct. The current transfers to the non-linear resistor (320) of the control breaking branch (300) and drops to zero. The tripping is successful and the tripping operation ends.

[0086] In the bus fault protection mode of the multi-port hybrid DC circuit breaker, when the first common bus has a ground fault, the multi-port hybrid DC circuit breaker cannot complete the bus isolation operation, and the failure backup protection will be started and the second fast mechanical switch (410) of the bus fault protection branch (400) will be controlled to close.

[0087] In the bus fault protection mode of the multi-port hybrid DC circuit breaker, when the second common bus has a ground fault, the bus differential protection will not operate in the normal operation mode of the multi-port hybrid DC circuit breaker. If a tripping operation is performed at this time, the bus differential protection will operate, and the DC circuit breaker will abort the tripping operation and start the backup failure protection.

[0088] Figure 5This is the topological diagram of the third embodiment of a multi-port hybrid DC circuit breaker when installed at the negative pole of a DC system. Compared with Figure 1 the first embodiment of the multi-port hybrid DC circuit breaker of the present invention shown, a bus fault protection branch (400) is added in this embodiment.

[0089] The bus fault protection branch (400) includes a second fast mechanical switch (410) and a unidirectional conduction switch (420) connected in series. The second fast mechanical switch (410) is connected to the second common bus, the unidirectional conduction switch (420) is connected to the first common bus, the midpoint of the bus fault protection branch (400) is connected to the DC bus, and the conduction direction of the unidirectional conduction switch (420) is from the DC bus to the first common bus. In addition, the breaking current direction of the unidirectional commutation switches (121-12n) of the current-carrying branches (101-10n) points to the port.

[0090] The operating modes of the multi-port hybrid DC circuit breaker in this embodiment include a normal operation mode, a tripping mode, a closing mode, and a bus fault protection mode.

[0091] In the normal operation mode of the multi-port hybrid DC circuit breaker, the first fast mechanical switches (111-11n) and the unidirectional commutation switches (121-12n) of each current-carrying branch (101-10n) are all in the conducting state, the unidirectional breaking switch (310) of the breaking branch (300) is in the off state, and the second fast mechanical switch (410) and the unidirectional conduction switch (420) of the bus fault protection branch (400) are all in the off state.

[0092] In the tripping mode of the multi-port hybrid DC circuit breaker, when the P k th port connected to the multi-port hybrid DC circuit breaker needs to be disconnected, the operation process is as follows.

[0093] The first step: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct, and the unidirectional commutation switches (121-12n) of all current-carrying branches (101-10n) to turn off. The current starts to transfer to the unidirectional breaking switch (310) of the breaking branch (300) through the commutation branches (201-20n).

[0094] The second step: When the current in all current-carrying branches (101-10n) is close to zero, control the first fast mechanical switch (11k) of the current-carrying branch (10k) of the P k th port to trip;

[0095] The third step: When the P kWhen the first fast mechanical switch (11k) of the port current-carrying branch (10k) is separated to the insulated voltage position, the unidirectional breaking switch (310) of the control breaking branch (300) is turned off, the unidirectional commutation switches (121 - 12n) of all current-carrying branches are turned on, and the P k port current is transferred to the non-linear resistor (320) of the breaking branch (300) and gradually decreases to zero. The current of the non-P k port resumes to its respective current-carrying branch, the opening is successful and the opening operation ends.

[0096] In the closing mode of the multi-port hybrid DC circuit breaker, when the P k port to be connected by the multi-port hybrid DC circuit breaker is required to be connected, the operation process is as follows.

[0097] The first step: Control the unidirectional breaking switch (310) of the breaking branch (300) to be turned on;

[0098] The second step: If it is not closed on a fault, control the first fast mechanical switch (11k) of the P k port current-carrying branch (10k) to be closed; if it is closed on a fault, control the unidirectional breaking switch (310) of the breaking branch (300) to be turned off, the closing fails and the closing operation ends.

[0099] The third step: When the first fast mechanical switch (11k) of the P k port current-carrying branch (10k) is in the closed position, control the unidirectional breaking switch (310) of the breaking branch (300) to be turned off, the closing is successful and the closing operation ends.

[0100] In the bus fault protection mode of the multi-port hybrid DC circuit breaker, when a DC bus grounding fault occurs, the operation process is as follows.

[0101] The first step: Control the unidirectional breaking switch (310) of the breaking branch (300) to be turned on, the unidirectional conduction switch (420) of the bus fault protection branch (400) to be turned on, and the unidirectional commutation switches (121 - 12n) of all current-carrying branches (101 - 10n) to be turned off. The current starts to be transferred through the commutation branches (201 - 20n) to the unidirectional breaking switch (310) of the breaking branch (300).

[0102] The second step: When the current of all current-carrying branches (101 - 10n) approaches zero, control the first fast mechanical switches (111 - 11n) of all current-carrying branches (101 - 10n) to trip.

[0103] Step 3: When the first fast mechanical switches (111 - 11n) of all current-carrying branches (101 - 10n) are separated to the insulation voltage position, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, and the unidirectional commutation switches (121 - 12n) of all current-carrying branches (101 - 10n) to turn on. The current transfers to the non-linear resistor (320) of the breaking branch (300) and drops to zero, indicating successful tripping and ending the tripping operation.

[0104] In the bus fault protection mode of the multi-port hybrid DC circuit breaker, when a first common bus grounding fault occurs, the bus differential protection in the normal operation mode of the multi-port hybrid DC circuit breaker will not operate. If a tripping operation is performed at this time, the bus differential protection will operate, and the DC circuit breaker will abort the tripping operation and start the backup failure protection.

[0105] In the bus fault protection mode of the multi-port hybrid DC circuit breaker, when a second common bus grounding fault occurs, the multi-port hybrid DC circuit breaker cannot complete the bus isolation operation, and will start the failure backup protection and control the second fast mechanical switch (410) of the bus fault protection branch (400) to close.

[0106] Figure 6 It is the topology diagram of the fourth embodiment of the multi-port hybrid DC circuit breaker when installed at the positive pole of the DC system in the embodiments of the present application. Compared with Figure 1 the embodiment shown, an auxiliary energy-consuming branch (500) is added in this embodiment.

[0107] The auxiliary energy-consuming branch (500) includes a diode (510) and a linear resistor (520) connected in series. One end of the auxiliary energy-consuming branch (500) is connected to the second common bus, and the other end is connected to the ground or the metal return line. The cathode of the diode (510) points to the second common bus. This topology scheme can be applied in situations where DC bus faults are not considered. The operating modes of the multi-port hybrid DC circuit breaker in this embodiment include the normal operation mode, the tripping mode, and the closing mode.

[0108] In the normal operation mode of the multi-port hybrid DC circuit breaker, the first fast mechanical switches (111 - 11n) and the unidirectional commutation switches (121 - 12n) of each current-carrying branch (101 - 10n) are in the on state, and the unidirectional breaking switch (310) of the breaking branch (300) is in the off state.

[0109] In the tripping mode of the multi-port hybrid DC circuit breaker, when the P k th port connected to the multi-port hybrid DC circuit breaker needs to be disconnected, the operation process is as follows.

[0110] Step 1: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct, and turn off the unidirectional commutation switches (121 - 12n) of all current-carrying branches (101 - 10n). The current starts to transfer through the commutation branches (201 - 20n) to the unidirectional breaking switch (310) of the breaking branch (300).

[0111] Step 2: When the current in all current-carrying branches (101 - 10n) approaches zero, control the fast mechanical switch (11k) of the P k th port current-carrying branch (10k) to trip.

[0112] Step 3: When the first fast mechanical switch (11k) of the P k th port current-carrying branch (10k) is separated to the insulation voltage position, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, and turn on the unidirectional commutation switches (121 - 12n) of all current-carrying branches. The current of the P k th port transfers to the non-linear resistor (320) of the breaking branch (300) and the linear resistor (520) of the auxiliary energy-consuming branch (500) and gradually drops to zero. The current of the non-P k th port resumes to its respective current-carrying branch, and the tripping is successful and the tripping operation ends.

[0113] In the closing mode of the multi-port hybrid DC circuit breaker, when the P k th port connected to the multi-port hybrid DC circuit breaker needs to be connected, the operation process is as follows.

[0114] Step 1: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct.

[0115] Step 2: If the multi-port hybrid DC circuit breaker is not closed on a fault, control the first fast mechanical switch (11k) of the P k th port current-carrying branch (10k) to close; if the multi-port hybrid DC circuit breaker is closed on a fault, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, the closing fails and the closing operation ends.

[0116] Step 3: When the first fast mechanical switch (11k) of the P k th port current-carrying branch (10k) is in the closed position, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, the closing is successful and the closing operation ends.

[0117] Figure 7 is the topological diagram of the fourth embodiment of the multi-port hybrid DC circuit breaker when installed at the negative pole of the DC system in the embodiments of the present application. Compared with Figure 1Embodiment. In this embodiment, an auxiliary energy-consuming branch (500) is added. The auxiliary energy-consuming branch (500) includes a diode (510) and a linear resistor (520) connected in series.

[0118] One end of the auxiliary energy-consuming branch (500) is connected to the first common bus, and the other end is connected to the ground or the metal return line. The anode of the diode (510) points to the first common bus. The multi-port hybrid DC circuit breaker of this embodiment can be applied in the occasion where the DC bus fault is not considered. The working modes of the multi-port hybrid DC circuit breaker include the normal operation mode, the opening mode, and the closing mode.

[0119] In the normal operation mode of the multi-port hybrid DC circuit breaker, the first fast mechanical switches (111-11n) and the unidirectional commutation switches (121-12n) of each current-carrying branch (101-10n) are in the conducting state, and the unidirectional breaking switch (310) of the breaking branch (300) is in the off state.

[0120] In the opening mode of the multi-port hybrid DC circuit breaker, when the Pth k port connected to the multi-port hybrid DC circuit breaker needs to be disconnected, the operation process is as follows.

[0121] First step: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct, and turn off the unidirectional commutation switches (121-12n) of all current-carrying branches (101-10n). The current starts to transfer through the commutation branches (201-20n) to the unidirectional breaking switch (310) of the breaking branch (300).

[0122] Second step: When the current of all current-carrying branches (101-10n) approaches zero, control the first fast mechanical switch (11k) of the current-carrying branch (10k) of the Pth k port to open.

[0123] Third step: When the first fast mechanical switch (11k) of the current-carrying branch (10k) of the Pth k port is separated to the insulation voltage position, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, and turn on the unidirectional commutation switches (121-12n) of all current-carrying branches. The current of the Pth k port transfers to the non-linear resistor (320) of the breaking branch (300) and the linear resistor (520) of the auxiliary energy-consuming branch (500) and gradually decreases to zero. The current of the non-Pth k port resumes to its respective current-carrying branch. The opening is successful and the opening operation ends.

[0124] In the closing mode of the multi-port hybrid DC circuit breaker, when the Pth kWhen the port needs to be connected, the operation process is as follows.

[0125] Step 1: Turn on the unidirectional disconnection switch (310) of the disconnection branch (300).

[0126] Step 2: If the multi-port hybrid DC circuit breaker is not closed on a fault, control the first fast mechanical switch (11k) of the P k port current-carrying branch (10k) to close; if the multi-port hybrid DC circuit breaker is closed on a fault, control the unidirectional disconnection switch (310) of the disconnection branch (300) to turn off, the closing fails and the closing operation ends.

[0127] Step 3: After the first fast mechanical switch (11k) of the P k port current-carrying branch (10k) is in the closed position, control the unidirectional disconnection switch (310) of the disconnection branch (300) to turn off, the closing is successful and the closing operation ends.

[0128] Figure 8 is the topology diagram of the fifth embodiment of the multi-port hybrid DC circuit breaker when installed at the positive pole of the DC system. Compared with Figure 1 the embodiment, this embodiment adds a bus fault protection branch (400) and an auxiliary energy-consuming branch (500).

[0129] The bus fault protection branch (400) includes a second fast mechanical switch (410). One end of the second fast mechanical switch (410) is connected to the DC bus, and the other end is connected to the first common bus. The auxiliary energy-consuming branch (500) includes a diode (510) and a linear resistor (520) connected in series. One end of the auxiliary energy-consuming branch (500) is connected to the second common bus, and the other end is connected to the ground or the metal return line. The cathode of the diode (510) points to the second common bus. The working modes of the multi-port hybrid DC circuit breaker in this embodiment include the normal operation mode, the tripping mode, the closing mode, and the bus fault protection mode.

[0130] In the normal operation mode of the multi-port hybrid DC circuit breaker, the first fast mechanical switches (111-11n) and the unidirectional commutation switches (121-12n) of each current-carrying branch (101-10n) are all in the on state, the unidirectional disconnection switch (310) of the disconnection branch (300) is in the off state, and the second fast mechanical switches (410) of the bus fault protection branch (400) are all in the off state.

[0131] In the tripping mode of the multi-port hybrid DC circuit breaker, when the P k port connected by the multi-port hybrid DC circuit breaker needs to be removed, the operation process is as follows.

[0132] Step 1: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct, and turn off the unidirectional commutation switches (121 - 12n) of all current-carrying branches (101 - 10n). The current starts to transfer through the commutation branches (201 - 20n) to the unidirectional breaking switch (310) of the breaking branch (300).

[0133] Step 2: When the current in all current-carrying branches (101 - 10n) approaches zero, control the first fast mechanical switch (11k) of the P k th-port current-carrying branch (10k) to trip.

[0134] Step 3: When the first fast mechanical switch (11k) of the P k th-port current-carrying branch (10k) is separated to the insulation voltage position, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, and turn on the unidirectional commutation switches (121 - 12n) of all current-carrying branches. The current of the P k th port transfers to the non-linear resistor (320) of the breaking branch (300) and the linear resistor (520) of the auxiliary energy-consuming branch (500) and gradually drops to zero. The current of the non-P k th port resumes to its respective current-carrying branch, and the tripping is successful and the tripping operation ends.

[0135] In the closing mode of the multi-port hybrid DC circuit breaker, when the P k th port connected to the multi-port hybrid DC circuit breaker needs to be connected, the operation process is as follows.

[0136] Step 1: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct.

[0137] Step 2: If the multi-port hybrid DC circuit breaker is not closed on a fault, control the first fast mechanical switch (11k) of the P k th-port current-carrying branch (10k) to close; if the multi-port hybrid DC circuit breaker is closed on a fault, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, and the closing fails and the closing operation ends.

[0138] Step 3: After the first fast mechanical switch (11k) of the P k th-port current-carrying branch (10k) is in the closed position, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, and the closing is successful and the closing operation ends.

[0139] In the bus fault protection mode of the multi-port hybrid DC circuit breaker, when a ground fault occurs in the DC bus, the first common bus, or the second common bus, the DC circuit breaker cannot complete the bus isolation operation, and the failure backup protection will be activated and the second fast mechanical switch (410) of the bus fault protection branch (400) will be controlled to close.

[0140] Figure 9 Fig. is the topological diagram of the fifth embodiment of the multi-port hybrid DC circuit breaker when installed at the negative pole of the DC system. Compared with Figure 1 the embodiment, this embodiment adds a bus fault protection branch (400) and an auxiliary energy dissipation branch (500).

[0141] The bus fault protection branch (400) includes a second fast mechanical switch (410). One end of the fast mechanical switch (410) is connected to the DC bus, and the other end is connected to the second common bus. The auxiliary energy dissipation branch (500) includes a diode (510) and a linear resistor (520) connected in series. One end of the auxiliary energy dissipation branch (500) is connected to the first common bus, and the other end is connected to the ground or the metal return line. The anode of the diode (510) points to the first common bus.

[0142] The working modes of the multi-port hybrid DC circuit breaker in this embodiment include the normal operation mode, the opening mode, the closing mode, and the bus fault protection mode.

[0143] In the normal operation mode of the multi-port hybrid DC circuit breaker, the first fast mechanical switches (111-11n) and the unidirectional commutation switches (121-12n) of each current-carrying branch (101-10n) are in the conducting state, the unidirectional breaking switch (310) of the breaking branch (300) is in the off state, and the second fast mechanical switches (410) of the bus fault protection branch (400) are in the off state.

[0144] In the opening mode of the multi-port hybrid DC circuit breaker, when the P k th port connected to the multi-port hybrid DC circuit breaker needs to be disconnected, the operation process is as follows.

[0145] Step 1: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct, and the unidirectional commutation switches (121-12n) of all current-carrying branches (101-10n) to turn off. The current starts to transfer through the commutation branches (201-20n) to the unidirectional breaking switch (310) of the breaking branch (300).

[0146] Step 2: When the current in all current-carrying branches (101-10n) approaches zero, control the first fast mechanical switch (11k) of the current-carrying branch (10k) of the P k th port to open.

[0147] Step 3: When the first fast mechanical switch (11k) of the current-carrying branch (10k) at the P k port is separated to the insulation voltage position, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, turn on the unidirectional commutation switches (121 - 12n) of all current-carrying branches, and transfer the current at the P k port to the non-linear resistor (320) of the breaking branch (300) and the linear resistor (520) of the auxiliary energy-consuming branch (500), and gradually decrease to zero. The current at the non-P k port resumes to its respective current-carrying branch, and the opening is successful and the opening operation ends.

[0148] In the closing mode of the multi-port hybrid DC circuit breaker, when the P k port to be connected by the multi-port hybrid DC circuit breaker needs to be accessed, the operation process is as follows.

[0149] Step 1: Control the unidirectional breaking switch (310) of the breaking branch (300) to turn on.

[0150] Step 2: If the multi-port hybrid DC circuit breaker is not closed on a fault, control the first fast mechanical switch (11k) of the current-carrying branch (10k) at the P k port to close; if the multi-port hybrid DC circuit breaker is closed on a fault, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, the closing fails and the closing operation ends.

[0151] Step 3: When the first fast mechanical switch (11k) of the current-carrying branch (10k) at the P k port is in the closed position, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, the closing is successful and the closing operation ends.

[0152] In the bus fault protection mode of the multi-port hybrid DC circuit breaker, when a grounding fault occurs in the DC bus or the first common bus or the second common bus, the DC circuit breaker cannot complete the bus isolation operation, and the failure backup protection will be started and control the second fast mechanical switch (410) of the bus fault protection branch (400) to close.

[0153] Figure 10 It is the topological diagram of the sixth embodiment of the multi-port hybrid DC circuit breaker installed at the positive pole of the DC system in the embodiment of the present application. Compared with Figure 1 the embodiment, an additional bus fault protection branch (400) and an additional auxiliary energy-consuming branch (500) are added.

[0154] The bus fault protection branch (400) includes a second fast mechanical switch (410) and a unidirectional conduction switch (420) connected in series. The second fast mechanical switch (410) is connected to the first common bus, and the unidirectional conduction switch (420) is connected to the second common bus. The midpoint of the bus fault protection branch (400) is connected to the DC bus, and the conduction direction of the unidirectional conduction switch (420) is from the second common bus to the DC bus.

[0155] The auxiliary energy-consuming branch (500) includes a diode (510) and a linear resistor (520) connected in series. One end of the auxiliary energy-consuming branch (500) is connected to the second common bus, and the other end is connected to the ground or the metal return line. The cathode of the diode (510) points to the second common bus. In addition, the breaking current direction of the unidirectional commutation switches (121 - 12n) of the current-carrying branches (101 - 10n) points to the DC bus. The operating modes of the multi-port hybrid DC circuit breaker in this embodiment include the normal operation mode, the opening mode, the closing mode, and the bus fault protection mode.

[0156] In the normal operation mode of the multi-port hybrid DC circuit breaker, the fast mechanical switches (111 - 11n) and the unidirectional commutation switches (121 - 12n) of each current-carrying branch (101 - 10n) are in the conducting state, the unidirectional breaking switch (310) of the breaking branch (300) is in the off state, and the second fast mechanical switch (410) and the unidirectional conduction switch (420) of the bus fault protection branch (400) are in the off state;

[0157] In the opening mode of the multi-port hybrid DC circuit breaker, when the P k th port connected to the multi-port hybrid DC circuit breaker needs to be disconnected, the operation process is as follows.

[0158] The first step: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct, and the unidirectional commutation switches (121 - 12n) of all current-carrying branches (101 - 10n) to turn off. The current starts to transfer to the unidirectional breaking switch (310) of the breaking branch (300) through the commutation branches (201 - 20n).

[0159] The second step: When the current in all current-carrying branches (101 - 10n) approaches zero, control the first fast mechanical switch (11k) of the current-carrying branch (10k) at the P k th port to open.

[0160] The third step: When the first fast mechanical switch (11k) of the current-carrying branch (10k) at the P k th port is separated to the insulation voltage position, control the unidirectional breaking switch (310) of the breaking branch (z300) to turn off, the unidirectional commutation switches (121 - 12n) of all current-carrying branches to conduct, and at the Pk The current of the port is transferred to the non-linear resistor (320) of the breaking branch (300) and the linear resistor (520) of the auxiliary energy-consuming branch (500), and gradually decreases to zero. It is not the P k The current of the port resumes to its respective current-carrying branch, the opening is successful, and the opening operation ends.

[0161] In the closing mode of the multi-port hybrid DC circuit breaker, when the P k port to be connected by the multi-port hybrid DC circuit breaker is required to be connected, the operation process is as follows.

[0162] Step 1: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct.

[0163] Step 2: If the multi-port hybrid DC circuit breaker is not closed on a fault, control the first fast mechanical switch (11k) of the P k port current-carrying branch (10k) to close; if the multi-port hybrid DC circuit breaker is closed on a fault, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, the closing fails, and the closing operation ends.

[0164] Step 3: After the first fast mechanical switch (11k) of the P k port current-carrying branch (10k) is in the closed position, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, the closing is successful, and the closing operation ends.

[0165] In the bus fault protection mode of the multi-port hybrid DC circuit breaker, when a DC bus grounding fault occurs, the operation process is as follows.

[0166] Step 1: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct, the unidirectional conducting switch (420) of the bus fault protection branch (400) to conduct, and the unidirectional commutation switches (121 - 12n) of all current-carrying branches (101 - 10n) to turn off. The current starts to transfer through the commutation branches (201 - 20n) to the unidirectional breaking switch (310) of the breaking branch (300).

[0167] Step 2: When the current of all current-carrying branches (101 - 10n) approaches zero, control the fast mechanical switches (111 - 11n) of all current-carrying branches (101 - 10n) to open.

[0168] Step 3: When the first fast mechanical switches (111 - 11n) of all current-carrying branches (101 - 10n) are separated to the insulation voltage position, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, and turn on the unidirectional commutation switches (121 - 12n) of all current-carrying branches (101 - 10n). The current is transferred to the non-linear resistor (320) of the breaking branch (300) and drops to zero, indicating successful opening and the end of the opening operation.

[0169] In the bus fault protection mode of the multi-port hybrid DC circuit breaker, when a first common bus grounding fault occurs, the multi-port hybrid DC circuit breaker cannot complete the bus isolation operation, and the backup protection for failure will be activated and the second fast mechanical switch (410) of the bus fault protection branch (400) will be controlled to close.

[0170] In the bus fault protection mode of the multi-port hybrid DC circuit breaker, the bus differential protection does not operate in the normal operation mode of the multi-port hybrid DC circuit breaker. If an opening operation is performed at this time, the bus differential protection will operate, and the DC circuit breaker will abort the opening operation and activate the backup protection for failure.

[0171] Figure 11 It is the topological diagram of the sixth embodiment of the multi-port hybrid DC circuit breaker when installed at the negative pole of the DC system in the embodiments of the present application.

[0172] Compared with Figure 1 the embodiment, this embodiment adds a bus fault protection branch (400) and an auxiliary energy-consuming branch (500).

[0173] The bus fault protection branch (400) includes a second fast mechanical switch (410) and a unidirectional conduction switch (420) connected in series. The fast mechanical switch (410) is connected to the second common bus, the unidirectional conduction switch (420) is connected to the first common bus, the midpoint of the bus fault protection branch (400) is connected to the DC bus, and the conduction direction of the unidirectional conduction switch (420) is from the DC bus to the first common bus. The auxiliary energy-consuming branch (500) includes a diode (510) and a linear resistor (520) connected in series.

[0174] One end of the auxiliary energy-consuming branch (500) is connected to the first common bus, and the other end is connected to the ground or the metal return line. The anode of the diode (510) points to the first common bus. In addition, the breaking current direction of the unidirectional commutation switches (121 - 12n) of the current-carrying branches (101 - 10n) points to the port. The operating modes of the multi-port hybrid DC circuit breaker in this embodiment include the normal operation mode, the opening mode, the closing mode, and the bus fault protection mode.

[0175] In the normal operation mode of the multi-port hybrid DC circuit breaker, the first fast mechanical switches (111 - 11n) and the unidirectional commutation switches (121 - 12n) of each current-carrying branch (101 - 10n) are in the conducting state, the unidirectional breaking switch (310) of the breaking branch (300) is in the off state, and the second fast mechanical switch (410) and the unidirectional conducting switch (420) of the bus fault protection branch (400) are in the off state.

[0176] In the tripping mode of the multi-port hybrid DC circuit breaker, when the P k th port connected to the multi-port hybrid DC circuit breaker needs to be disconnected, the operation process is as follows.

[0177] Step 1: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct, and turn off the unidirectional commutation switches (121 - 12n) of all current-carrying branches (101 - 10n). The current starts to transfer through the commutation branches (201 - 20n) to the unidirectional breaking switch (310) of the breaking branch (300).

[0178] Step 2: When the current in all current-carrying branches (101 - 10n) approaches zero, control the first fast mechanical switch (11k) of the current-carrying branch (10k) of the P k th port to trip.

[0179] Step 3: When the first fast mechanical switch (11k) of the current-carrying branch (10k) of the P k th port is separated to the insulation voltage position, control the unidirectional breaking switch (310) of the breaking branch (300) to turn off, and turn on the unidirectional commutation switches (121 - 12n) of all current-carrying branches. The current of the P k th port transfers to the non-linear resistor (320) of the breaking branch (300) and the linear resistor (520) of the auxiliary energy-consuming branch (500) and gradually drops to zero. The current of the non-P k th port resumes to its respective current-carrying branch, and the tripping is successful and the tripping operation ends.

[0180] In the closing mode of the multi-port hybrid DC circuit breaker, when the P k th port connected to the multi-port hybrid DC circuit breaker needs to be connected, the operation process is as follows.

[0181] Step 1: Control the unidirectional breaking switch (310) of the breaking branch (300) to conduct.

[0182] Step 2: If it is not closed onto a fault, then control the P kThe first fast mechanical switch (11k) of the port current-carrying branch (10k) closes; if closed onto a fault, the unidirectional breaking switch (310) of the control breaking branch (300) shuts off, the closing fails, and the closing operation ends.

[0183] Step 3: When the Pth k After the first fast mechanical switch (11k) of the port current-carrying branch (10k) is in the closed position, the unidirectional breaking switch (310) of the control breaking branch (300) shuts off, the closing is successful, and the closing operation ends.

[0184] In the bus fault protection mode of the multi-port hybrid DC circuit breaker, when a DC bus ground fault occurs, the operation process is as follows.

[0185] Step 1: The unidirectional breaking switch (310) of the control breaking branch (300) conducts, the unidirectional conducting switch (420) of the bus fault protection branch (400) conducts, and the unidirectional commutation switches (121 - 12n) of all current-carrying branches (101 - 10n) shut off. The current starts to transfer through the commutation branches (201 - 20n) to the unidirectional breaking switch (310) of the breaking branch (300).

[0186] Step 2: When the current in all current-carrying branches (101 - 10n) approaches zero, control the first fast mechanical switches (111 - 11n) of all current-carrying branches (101 - 10n) to open.

[0187] Step 3: When the first fast mechanical switches (111 - 11n) of all current-carrying branches (101 - 10n) are separated to the insulation voltage position, control the unidirectional breaking switch (310) of the breaking branch (300) to shut off and the unidirectional commutation switches (121 - 12n) of all current-carrying branches (101 - 10n) to conduct. The current transfers to the non-linear resistor (320) of the breaking branch (300) and drops to zero. The opening is successful and the opening operation ends.

[0188] In the bus fault protection mode of the multi-port hybrid DC circuit breaker, when a first common bus ground fault occurs, the bus differential protection in the normal operation mode of the multi-port hybrid DC circuit breaker will not operate. If a trip operation is performed at this time, the bus differential protection will operate, the DC circuit breaker aborts the trip operation, and the backup failure protection is started.

[0189] In the bus fault protection mode of the multi-port hybrid DC circuit breaker, when a second common bus ground fault occurs, the multi-port hybrid DC circuit breaker cannot complete the bus isolation operation, starts the failure backup protection, and controls the second fast mechanical switch (410) of the bus fault protection branch (400) to close.

[0190] Figures 1 - 11Among them, the fast mechanical switch (111-11n) includes at least one mechanical switch break connected in series, the diode (211-21n, 221-22n, 510) includes at least one diode connected in series, the unidirectional commutation switch (121-12n) includes at least one first switch semiconductor device connected in series, and the unidirectional breaking switch (310) includes at least one first switch semiconductor device connected in series. The first switch semiconductor device is one or a combination of IGBT, IEGT, IGCT, and MOSFET.

[0191] The unidirectional conduction switch (420) includes at least one diode (421) connected in series and at least one second switch semiconductor device (422) connected in series. The diode (421) and the second switch semiconductor device (422) are connected in series with each other. The second switch semiconductor device includes one or a combination of SCR, IGBT, IEGT, IGCT, and MOSFET. In addition, arresters are usually used in non-linear resistance engineering.

[0192] Figure 12 It is a schematic diagram of the breaking switch of a multi-port hybrid DC circuit breaker according to an embodiment of the present application, including a parallel group of a plurality of unidirectional breaking switches (310) and non-linear resistors (320) connected in series.

[0193] The above embodiments are only used to illustrate the technical idea of the present application, and the protection scope of the present application cannot be limited thereby. Any modification made on the basis of the technical solution according to the technical idea proposed by the present application falls within the protection scope of the present application.

Claims

1. A multi-port hybrid DC circuit breaker, comprising: At least two current-carrying branches, each current-carrying branch including a first fast mechanical switch and a unidirectional commutation switch connected in series, one ends of the current-carrying branches are connected to each other to form a DC bus, and the breaking current directions of the unidirectional commutation switches of each current-carrying branch are the same; At least two commutation branches, each commutation branch including a diode upper arm and a diode lower arm connected in series in the same direction, the other end of each current-carrying branch is correspondingly connected to the midpoint of each commutation branch to form a port; A breaking branch, the breaking branch including a unidirectional breaking switch and a non-linear resistor connected in parallel, the breaking branch and the commutation branch are connected in parallel to form a first common bus and a second common bus, the breaking current direction of the unidirectional breaking switch of the breaking branch is from the first common bus to the second common bus, the cathode of the diode upper arm of the commutation branch is connected to the first common bus, and the anode of the diode lower arm of the commutation branch is connected to the second common bus; One auxiliary energy-consuming branch; One bus fault protection branch, including a second fast mechanical switch and a unidirectional conduction switch connected in series, both ends of the bus fault protection branch are respectively connected to the first common bus and the second common bus, and the midpoint of the bus fault protection branch is connected to the DC bus; wherein: When the multi-port hybrid DC circuit breaker is installed at the positive pole of the DC system, the second fast mechanical switch is connected to the first common bus, the unidirectional conduction switch is connected to the second common bus, the conduction direction of the unidirectional conduction switch is from the second common bus to the DC bus, the breaking current direction of the unidirectional commutation switch of the current-carrying branch points to the DC bus, one end of the auxiliary energy-consuming branch is connected to the second common bus, and the other end of the auxiliary energy-consuming branch is connected to the ground or the metal return line; When the multi-port hybrid DC circuit breaker is installed at the negative pole of the DC system, the second fast mechanical switch is connected to the second common bus, the unidirectional conduction switch is connected to the first common bus, the conduction direction of the unidirectional conduction switch is from the DC bus to the first common bus, the breaking current direction of the unidirectional commutation switch of the current-carrying branch points to the port, one end of the auxiliary energy-consuming branch is connected to the first common bus, and the other end of the auxiliary energy-consuming branch is connected to the ground or the metal return line; The bus fault protection branch is used to provide a bus fault protection mode, and the multi-port hybrid DC circuit breaker is controlled based on the fault type when in the bus fault protection mode; wherein: When the fault type is a DC bus grounding fault, control the unidirectional breaking switch of the breaking branch to conduct, the unidirectional conduction switch of the bus fault protection branch to conduct, and the unidirectional commutation switches of all current-carrying branches to turn off, and the current starts to transfer to the unidirectional breaking switch of the breaking branch through the commutation branch; When the current in all current-carrying branches approaches zero, control the fast mechanical switches of all current-carrying branches to trip; When the fast mechanical switches of all current-carrying branches are separated to the insulation voltage position, control the unidirectional breaking switch of the breaking branch to turn off and the unidirectional commutation switches of all current-carrying branches to turn on. The current transfers to the non-linear resistor of the breaking branch and drops to zero, and the opening is successful and the opening operation ends. When the fault type is that the multi-port hybrid DC circuit breaker is installed at the positive pole of the DC system and a first common bus grounding fault occurs, the multi-port hybrid DC circuit breaker cannot complete the bus isolation operation, and the failure backup protection will be started and the fast mechanical switch of the bus fault protection branch will be controlled to close. When the fault type is that the multi-port hybrid DC circuit breaker is installed at the negative pole of the DC system and a second common bus grounding fault occurs, the multi-port hybrid DC circuit breaker cannot complete the bus isolation operation, and the failure backup protection will be started and the fast mechanical switch of the bus fault protection branch will be controlled to close. When the fault type is that the multi-port hybrid DC circuit breaker is installed at the positive pole of the DC system and a second common bus grounding fault occurs, the bus differential protection will not operate in the normal operation mode of the multi-port hybrid DC circuit breaker. If the opening operation is performed at this time, the bus differential protection will operate, and the multi-port hybrid DC circuit breaker will abort the opening operation and start the backup failure protection. When the fault type is that the multi-port hybrid DC circuit breaker is installed at the negative pole of the DC system and a first common bus grounding fault occurs, the bus differential protection will not operate in the normal operation mode of the multi-port hybrid DC circuit breaker. If the opening operation is performed at this time, the bus differential protection will operate, and the multi-port hybrid DC circuit breaker will abort the opening operation and start the backup failure protection.

2. The multi-port hybrid DC circuit breaker according to claim 1, The auxiliary energy-consuming branch includes a diode and a linear resistor connected in series; wherein When the multi-port hybrid DC circuit breaker is installed at the positive pole of the DC system, the cathode of the diode points to the second common bus; When the multi-port hybrid DC circuit breaker is installed at the negative pole of the DC system, the anode of the diode points to the first common bus.

3. The multi-port hybrid DC circuit breaker according to any one of claims 1 to 2, wherein The first fast mechanical switch or the second fast mechanical switch includes at least one mechanical switch break connected in series, the diode includes at least one diode connected in series, the unidirectional commutation switch includes at least one first switch semiconductor device connected in series, the unidirectional breaking switch includes at least one first switch semiconductor device connected in series, the unidirectional conduction switch includes at least one diode connected in series and at least one second switch semiconductor device connected in series, and the diode and the second switch semiconductor device are connected in series with each other; The first switch semiconductor device includes at least one of IGBT, IEGT, IGCT, MOSFET; the second switch semiconductor device includes at least one of SCR, IGBT, IEGT, IGCT, MOSFET.

4. A control method for a multi-port hybrid DC circuit breaker as described in any one of claims 1 to 3, comprising: Controlling the on / off of the current-carrying branch, commutation branch, and breaking branch based on the operating mode of the multi-port hybrid DC circuit breaker, where the operating mode includes normal operation mode, opening mode, closing mode, and bus fault protection mode; When the multi-port hybrid DC circuit breaker is in the bus fault protection mode, controlling based on the fault type; where: When the fault type is a DC bus grounding fault, controlling the unidirectional breaking switch of the breaking branch to conduct, the unidirectional conducting switch of the bus fault protection branch to conduct, and the unidirectional commutation switches of all current-carrying branches to turn off, and the current starts to transfer through the commutation branch to the unidirectional breaking switch of the breaking branch; When the current in all current-carrying branches approaches zero, controlling the fast mechanical switches of all current-carrying branches to open; When the fast mechanical switches of all current-carrying branches are separated to the insulation voltage position, controlling the unidirectional breaking switch of the breaking branch to turn off and the unidirectional commutation switches of all current-carrying branches to conduct, and the current transfers to the non-linear resistor of the breaking branch and drops to zero, and the opening is successful and the opening operation ends; When the fault type is that the multi-port hybrid DC circuit breaker is installed at the positive pole of the DC system and the first common bus has a grounding fault, the multi-port hybrid DC circuit breaker cannot complete the bus isolation operation, and the failure backup protection will be started and the fast mechanical switch of the bus fault protection branch will be controlled to close; When the fault type is that the multi-port hybrid DC circuit breaker is installed at the negative pole of the DC system and the second common bus has a grounding fault, the multi-port hybrid DC circuit breaker cannot complete the bus isolation operation, and the failure backup protection will be started and the fast mechanical switch of the bus fault protection branch will be controlled to close; When the fault type is that the multi-port hybrid DC circuit breaker is installed at the positive pole of the DC system and the second common bus has a grounding fault, the bus differential protection will not act in the normal operation mode of the multi-port hybrid DC circuit breaker. If the opening operation is performed at this time, the bus differential protection will act, and the multi-port hybrid DC circuit breaker will abort the opening operation and start the backup failure protection; When the fault type is that the multi-port hybrid DC circuit breaker is installed at the negative pole of the DC system and the first common bus has a grounding fault, the bus differential protection will not act in the normal operation mode of the multi-port hybrid DC circuit breaker. If the opening operation is performed at this time, the bus differential protection will act, and the multi-port hybrid DC circuit breaker will abort the opening operation and start the backup failure protection.

5. The control method as described in claim 4, where When the multi-port hybrid DC circuit breaker is in the normal operation mode, each current-carrying branch is in the conducting state, the breaking branch is in the off state, and when the multi-port hybrid DC circuit breaker includes a bus fault protection branch, the bus fault protection branch is in the off state.

6. The control method as described in claim 4, where the multi-port hybrid DC circuit breaker further includes an auxiliary energy-consuming branch, including a diode and a linear resistor connected in series; where: When the multi-port hybrid DC circuit breaker is installed at the positive pole of the DC system, one end of the auxiliary energy-consuming branch is connected to the second common bus, the other end of the auxiliary energy-consuming branch is connected to the ground or the metal return line, and the cathode of the diode points to the second common bus; When the multi-port hybrid DC circuit breaker is installed at the negative pole of the DC system, one end of the auxiliary energy-consuming branch is connected to the first common bus, the other end of the auxiliary energy-consuming branch is connected to the ground or the metal return line, and the anode of the diode points to the first common bus; When the multi-port hybrid DC circuit breaker is in the open circuit mode, when any of the ports connected to the multi-port hybrid DC circuit breaker needs to be disconnected, it includes: Controlling the unidirectional disconnection switch of the disconnection branch to conduct, and the unidirectional commutation switches of all current-carrying branches to turn off, and the current starts to transfer to the unidirectional disconnection switch of the disconnection branch through the commutation branch; When the current in all current-carrying branches approaches zero, controlling the fast mechanical switch of the current-carrying branch where the port to be disconnected is located to open; When the fast mechanical switch of the current-carrying branch where the port to be disconnected is located is separated to the insulation voltage position, controlling the unidirectional disconnection switch of the disconnection branch to turn off, and the unidirectional commutation switches of all current-carrying branches to conduct. The current of the port to be disconnected transfers to the non-linear resistor of the disconnection branch and the linear resistor of the auxiliary energy-consuming branch and gradually drops to zero. The currents of the other ports except the port to be disconnected return to their respective current-carrying branches, and the disconnection is successful and the disconnection operation ends.

7. The control method according to claim 4, wherein When the multi-port hybrid DC circuit breaker is in the closed circuit mode, when any port connected to the multi-port hybrid DC circuit breaker needs to be connected, it includes: Controlling the unidirectional disconnection switch of the disconnection branch to conduct; If the multi-port hybrid DC circuit breaker is not closed on a fault, controlling the fast mechanical switch of the current-carrying branch where the port to be connected is located to close; if the multi-port hybrid DC circuit breaker is closed on a fault, controlling the unidirectional disconnection switch of the disconnection branch to turn off, and the closing fails and the closing operation ends; After the fast mechanical switch of the current-carrying branch where the port to be connected is located is in the closed position, controlling the unidirectional disconnection switch of the disconnection branch to turn off, and the closing is successful and the closing operation ends.

Images