Current injection type DC circuit breaker and control method

Abstract

The present invention provides a current injection type DC circuit breaker and control method, the current injection type DC circuit breaker includes: multiple current modules, current injection modules, energy consumption modules, disconnection modules and multiple isolation modules, wherein one end of the multiple current modules is connected to the DC bus wiring port, and the other end is connected to each DC line wiring port, and the DC bus wiring port and the DC line wiring port are arranged one by one; one end of each isolation module is connected to the corresponding DC line, and the other end is connected to one end of the current injection module; the other end of the current injection module is respectively connected to one end of the energy consumption module and one end of the disconnection module; the other end of the energy consumption module and the other end of the disconnection module are connected to the DC bus. By implementing the present invention, the equipment investment of the circuit breaker is reduced, which is conducive to the construction of multi-terminal and DC power grids.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a current injection type DC circuit breaker and a control method thereof. Background Art

[0002] High-voltage DC circuit breakers are one of the core equipment for multi-terminal and DC power grid construction. Their technical and economic performance directly affects the flexibility and extensiveness of DC power grid applications. With the large-scale development of renewable energy such as wind and solar, the transmission capacity and application scale of DC power grids will continue to increase, and the grid structure will become increasingly complex. Large-scale applications will place higher requirements on the technical and economic performance of high-voltage DC circuit breakers.

[0003] At present, there are two main technical routes for high-voltage DC circuit breakers: hybrid and mechanical. The mechanical solution has bottleneck problems such as long small current breaking time and difficulty in fast reclosing, which limits the improvement of the breaking performance of the solution, and its cost increases significantly with the increase in the number of reclosing times. Therefore, compared with mechanical DC circuit breakers, hybrid solutions are more widely used in engineering. However, current hybrid DC circuit breakers usually use a large number of fully controlled power electronic devices. As the demand for breaking current increases, the devices will be further enlarged, resulting in a significant increase in cost. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect of high cost of hybrid DC circuit breakers in the prior art, thereby providing a current injection DC circuit breaker and a control method.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] In a first aspect, an embodiment of the present invention provides a current injection DC circuit breaker, comprising: a plurality of current-passing modules, a current injection module, an energy consumption module, a disconnecting module and a plurality of isolation modules, wherein one end of the plurality of current-passing modules is connected to a DC bus wiring port, and the other end is connected to each DC line wiring port, and the DC bus wiring port and the DC line wiring port are arranged in a one-to-one correspondence; one end of each of the isolation modules is connected to its corresponding DC line, and the other end is connected to one end of the current injection module; the other end of the current injection module is respectively connected to one end of the energy consumption module and one end of the disconnecting module; the other end of the energy consumption module and the other end of the disconnecting module are connected to the DC bus.

[0007] Optionally, the throughflow module comprises at least one mechanical switch.

[0008] Optionally, the isolation module comprises: a mechanical switch and at least one bidirectional power electronic switch unit, wherein the mechanical switch is connected in series with each of the bidirectional power electronic switch units.

[0009] Optionally, the isolation module includes: a plurality of bidirectional power electronic switch units connected in series and a nonlinear resistor connected in parallel with the plurality of bidirectional power electronic switch units connected in series.

[0010] Optionally, the current injection module includes a coupling reactor, a charging capacitor, a thyristor and a diode connected in reverse parallel to the thyristor, wherein one end of the secondary side of the coupling reactor is respectively connected to the other end of each of the isolation modules, and the other end is respectively connected to one end of the energy consumption module and one end of the disconnection module; one end of the primary side of the coupling reactor is connected to one end of the charging capacitor, and the other end of the charging capacitor is respectively connected to the cathode of the thyristor and the anode of the diode connected in reverse parallel to the thyristor; the other end of the primary side of the coupling reactor is respectively connected to the anode of the thyristor and the cathode of the diode connected in reverse parallel to the thyristor.

[0011] Optionally, the energy consumption module is a lightning arrester.

[0012] Optionally, the disconnecting module includes at least one bidirectional power electronic switch unit.

[0013] Optionally, the bidirectional power electronic switch includes an IGBT device and a diode connected in reverse parallel to the IGBT device.

[0014] In a second aspect, an embodiment of the present invention provides a current injection type DC circuit breaker control method, which is applied to the current injection type DC circuit breaker described in the first aspect of the embodiment of the present invention, and the control method includes: when receiving the current DC line fault disconnection command, disconnecting the current flow module in the current DC line and the isolation module connected to other DC lines, and turning on the isolation module connected to the current DC line and the breaking module in the commutation branch; controlling the current injection module to be put into operation, injecting reverse current into the current DC line, so that the fault current of the current DC line flows into the commutation branch; when the current flow module and the isolation module connected to other lines have the ability to withstand transient breaking voltage, locking the breaking unit and transferring the current to the energy consumption module for clearing.

[0015] The technical solution of the present invention has the following advantages:

[0016] The current injection type DC circuit breaker provided by the present invention includes: multiple current modules, current injection modules, energy consumption modules, disconnection modules and multiple isolation modules, wherein one end of the multiple current modules is connected to the DC bus wiring port, and the other end is connected to each DC line wiring port, and the DC bus wiring port and the DC line wiring port are arranged one by one; one end of each isolation module is connected to its corresponding DC line, and the other end is connected to one end of the current injection module; the other end of the current injection module is respectively connected to one end of the energy consumption module and one end of the disconnection module; the other end of the energy consumption module and the other end of the disconnection module are connected to the DC bus. The above-mentioned current injection type DC circuit breaker can be used in a multi-port structure, and has the short-circuit current breaking capacity of multiple DC lines, which reduces the overall volume and cost of the DC circuit breaker, so that it has good technical and economic performance, and can meet the large-scale application requirements of high-voltage DC circuit breakers. Furthermore, by sharing the commutation branch, the equipment investment of the DC circuit breaker is greatly reduced, which is conducive to the construction of multi-terminal and DC power grids.

[0017] The current injection type DC circuit breaker control method provided by the present invention configures the current injection type DC circuit breaker in a multi-port DC system, and uses the current injection type DC circuit breaker to achieve zero arc breaking and blocking of fault current. At the same time, the function of reclosing enables it to have the short-circuit current breaking capacity of multiple DC lines, reduces the overall size and cost of the DC circuit breaker, can meet the large-scale application requirements of high-voltage DC circuit breakers, and greatly reduces the equipment investment of the DC circuit breaker, which is conducive to the construction of multi-terminal and DC power grids. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 is a structural diagram of a specific example of a current injection type DC circuit breaker in an embodiment of the present invention;

[0020] Figure 2 A topological structure diagram of a specific example of an isolation module in an embodiment of the present invention;

[0021] Figure 3 is a topological structure diagram of another specific example of an isolation module in an embodiment of the present invention;

[0022] Figure 4 A topological structure diagram of a specific example of a bidirectional power electronic switch unit in an embodiment of the present invention;

[0023] Figure 5 is a topological structure diagram of another specific example of a bidirectional power electronic switch unit in an embodiment of the present invention;

[0024] Figure 6 is a topological structure diagram of another specific example of a bidirectional power electronic switch unit in an embodiment of the present invention;

[0025] Figure 7 is a topological structure diagram of a specific example of a current injection module in an embodiment of the present invention;

[0026] Figure 8 It is a flowchart of a specific example of a current injection type DC circuit breaker control method in an embodiment of the present invention;

[0027] Fig. 9 FIG. 4 is a structural diagram of another specific example of a current injection type DC circuit breaker in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] The embodiment of the present invention provides a current injection type DC circuit breaker, which is applied to multi-terminal and flexible DC power grids. Figure 1 As shown, it includes: multiple current-passing modules, current injection modules, energy consumption modules, disconnecting modules and multiple isolation modules, wherein one end of the multiple current-passing modules is connected to the DC bus wiring port, and the other end is connected to each DC line wiring port, and the DC bus wiring port and the DC line wiring port are arranged in a one-to-one correspondence; one end of each isolation module is connected to the corresponding DC line, and the other end is connected to one end of the current injection module; the other end of the current injection module is respectively connected to one end of the energy consumption module and one end of the disconnecting module; the other end of the energy consumption module and the other end of the disconnecting module are connected to the DC bus.

[0033] In a specific embodiment, a current injection type DC circuit breaker is installed in a DC power grid to realize the conduction of a steady-state current in the DC line when the DC line is operating normally, and to transfer the fault current to the commutation branch after detecting a fault in the DC line, thereby realizing a fault blocking function. Figure 1 Not shown.

[0034] The current injection type DC circuit breaker provided by the present invention includes: multiple current modules, current injection modules, energy consumption modules, disconnection modules and multiple isolation modules, wherein one end of the multiple current modules is connected to the DC bus wiring port, and the other end is connected to each DC line wiring port, and the DC bus wiring port and the DC line wiring port are arranged one by one; one end of each isolation module is connected to its corresponding DC line, and the other end is connected to one end of the current injection module; the other end of the current injection module is respectively connected to one end of the energy consumption module and one end of the disconnection module; the other end of the energy consumption module and the other end of the disconnection module are connected to the DC bus. The above-mentioned current injection type DC circuit breaker can be used in a multi-port structure, and has the short-circuit current breaking capacity of multiple DC lines, which reduces the overall volume and cost of the DC circuit breaker, so that it has good technical and economic performance, and can meet the large-scale application requirements of high-voltage DC circuit breakers. Furthermore, by sharing the commutation branch, the equipment investment of the DC circuit breaker is greatly reduced, which is conducive to the construction of multi-terminal and DC power grids.

[0035] In one embodiment, the throughflow module comprises at least one mechanical switch.

[0036] In a specific embodiment, the flow module is composed of at least one fast mechanical switch, which is mainly used to conduct the rated current when the system is in steady state operation and to withstand the transient voltage during the opening process of the DC circuit breaker after a system fault. By only providing a mechanical switch in the flow module, the operating loss is approximately zero, and no water cooling system is required, thereby improving the reliability of the circuit breaker.

[0037] In one embodiment, if Figure 2 As shown, the isolation module includes: a mechanical switch and at least one bidirectional power electronic switch unit, wherein the mechanical switch is connected in series with each bidirectional power electronic switch unit.

[0038] In a specific embodiment, the isolation module is a fast switch unit with bidirectional conduction and blocking capabilities, which is mainly used to select and implement the short-circuit current of the fault line and the transient breaking voltage isolation of the non-fault line. Figure 3 As shown, the isolation module may further include: a plurality of bidirectional power electronic switch units connected in series and a nonlinear resistor connected in parallel with the plurality of bidirectional power electronic switch units connected in series. Figure 4 , Figure 5 and Figure 6 As shown in FIG. 1 , a typical topology of a bidirectional power electronic switch unit is shown. Specifically, the bidirectional power electronic switch unit may be as follows: Figure 4 The reverse series connection of the fully controlled devices shown in the figure can be as follows Figure 5 The full-bridge module composed of the fully controlled devices shown in the figure can also be composed of Figure 6 The diodes shown form the construction of a full-bridge module.

[0039] In one embodiment, if Figure 7 As shown, the current injection module includes a coupling reactor L1, a charging capacitor C1, a thyristor T1 and a diode D1 connected in reverse parallel to the thyristor T1, wherein one end of the secondary side of the coupling reactor L1 is respectively connected to the other end of each isolation module, and the other end is respectively connected to one end of the energy consumption module and one end of the disconnection module; one end of the primary side of the coupling reactor L1 is connected to one end of the charging capacitor C1, and the other end of the charging capacitor C1 is respectively connected to the cathode of the thyristor T1 and the anode of the diode D1 connected in reverse parallel to the thyristor T1; the other end of the primary side of the coupling reactor L1 is respectively connected to the anode of the thyristor T1 and the cathode of the diode D1 connected in reverse parallel to the thyristor T1.

[0040] In a specific embodiment, the current injection module is mainly used to realize the transfer of the faulty DC pole line short-circuit current.

[0041] In one embodiment, the energy consumption module is a lightning arrester.

[0042] In a specific embodiment, the energy consumption unit is a series connection of non-linear resistors, which is used to absorb electromagnetic energy of the system inductive components and clear the short-circuit current.

[0043] In one embodiment, the disconnect module includes at least one bidirectional power electronic switch unit.

[0044] In a specific embodiment, the disconnect module is a high-speed bidirectional power electronic switch unit for realizing short-circuit current disconnection, and its typical structure is a fully controlled device reverse series or bridge module. In an embodiment of the present invention, the bidirectional power electronic switch unit includes an IGBT device and a diode reversely connected in parallel with the IGBT device.

[0045] The embodiment of the present invention further provides a current injection type DC circuit breaker control method, which is applied to the above current injection type DC circuit breaker, such as Figure 8 As shown, the control method includes the following steps:

[0046] Step S1: upon receiving the current DC line fault disconnection command, disconnect the current-passing module in the current DC line and the isolation module connected to other DC lines, and turn on the isolation module connected to the current DC line and the disconnection module in the commutation branch.

[0047] Step S2: Control the current injection module to be turned on, and inject reverse current into the current DC line, so that the fault current of the current DC line flows into the commutation branch.

[0048] Step S3: When the current-carrying module and the isolation module connected to other lines have the ability to withstand the transient breaking voltage, the breaking unit is locked to transfer the current to the energy consumption module for clearing.

[0049] In a specific embodiment, the control method is specifically as follows: Fig. 9 Taking the current injection type DC circuit breaker shown in the figure as an example, first, in steady-state operation, the disconnecting module is in a locked state, each isolation module is in a blocked state, the mechanical switches K11 and K12 in isolation module 1 and isolation module 2 are in a conducting state, and the power electronic switch IGBT in the disconnecting module is in a locked state. The system load current flows through the mechanical switches K1 and K2 in the flow modules on each DC line.

[0050] When the circuit breaker detects a fault in DC line 1, it issues a trip command for mechanical switches K1 and K12. When mechanical switches K1 and K12 have a certain opening distance, the IGBT in the breaking module and the IGBT in the isolation module 1 are turned on, and the thyristor T in the current injection module is triggered at the same time. The injected current realizes the current zero crossing of the mechanical switch K1 and extinguishes the arc. When the opening distance of the mechanical switches K1 and K12 reaches a sufficient level to withstand the transient breaking voltage peak, the IGBT in the breaking module is locked, and the current is forced to be transferred to the energy consumption module MOV, realizing current removal and completing the shutdown.

[0051] When the current rise rate and current amplitude of DC line 1 return to normal, that is, the fault of DC line 1 is cleared, the IGBT in the disconnecting module is first locked to control the commutation branch connected to the current DC line to stop working, and the mechanical switch K1 is closed to control the flow module in the DC line to connect the current DC line. If the fault still exists, the IGBT in the disconnecting module is closed again to control the commutation branch connected to the current DC line to start working, so that the fault current of the current DC line flows into the energy consumption module in the commutation branch to clear the fault current.

[0052] The current injection type DC circuit breaker control method provided by the present invention configures the current injection type DC circuit breaker in a multi-port DC system, and uses the current injection type DC circuit breaker to achieve zero arc breaking and blocking of fault current. At the same time, the function of reclosing enables it to have the short-circuit current breaking capacity of multiple DC lines, reduces the overall size and cost of the DC circuit breaker, can meet the large-scale application requirements of high-voltage DC circuit breakers, and greatly reduces the equipment investment of the DC circuit breaker, which is conducive to the construction of multi-terminal and DC power grids.

[0053] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. A current injection type DC circuit breaker, characterized in that: include: Multiple current-passing modules, current injection modules, energy consumption modules, disconnection modules and multiple isolation modules, among which, One end of each of the plurality of current-passing modules is connected to a DC bus wiring port, and the other end is connected to each DC line wiring port, and the DC bus wiring port is arranged in a one-to-one correspondence with the DC line wiring port; One end of each isolation module is connected to its corresponding DC line, and the other end is connected to one end of the current injection module; the other end of the current injection module is respectively connected to one end of the energy consumption module and one end of the disconnection module; the other end of the energy consumption module and the other end of the disconnection module are connected to the DC bus; The throughflow module includes at least one mechanical switch; The isolation module comprises: a mechanical switch and at least one bidirectional power electronic switch unit, wherein the mechanical switch is connected in series with each of the bidirectional power electronic switch units.

2. The current injection type DC circuit breaker according to claim 1, characterized in that: The isolation module comprises: a plurality of bidirectional power electronic switch units connected in series and a nonlinear resistor connected in parallel with the plurality of bidirectional power electronic switch units connected in series.

3. The current injection type DC circuit breaker according to claim 1, characterized in that: The current injection module includes a coupling reactor, a charging capacitor, a thyristor, and a diode connected in reverse parallel with the thyristor, wherein: One end of the secondary side of the coupling reactor is connected to the other end of each isolation module, and the other end is connected to one end of the energy consumption module and one end of the disconnection module; One end of the primary side of the coupling reactor is connected to one end of the charging capacitor, and the other end of the charging capacitor is respectively connected to the cathode of the thyristor and the anode of the diode connected in reverse parallel to the thyristor; The other end of the primary side of the coupling reactor is respectively connected to the anode of the thyristor and the cathode of the diode connected in reverse parallel to the thyristor.

4. The current injection type DC circuit breaker according to claim 1, characterized in that: The energy consumption module is a lightning arrester.

5. The current injection type DC circuit breaker according to claim 1, characterized in that: The disconnecting module includes at least one bidirectional power electronic switch unit.

6. The current injection type DC circuit breaker according to claim 5, characterized in that: The bidirectional power electronic switch unit includes an IGBT device and a diode connected in reverse parallel to the IGBT device.

7. A current injection type DC circuit breaker control method, applied to the current injection type DC circuit breaker according to any one of claims 1 to 6, characterized in that: The control method comprises: Upon receiving a current DC line fault disconnection command, disconnect the current-passing module in the current DC line and the isolation module connected to other DC lines, and connect the isolation module connected to the current DC line and the disconnection module in the commutation branch; Controlling the current injection module to be put into operation, injecting a reverse current into the current DC line, so that the fault current of the current DC line flows into the commutation branch; When the current-carrying module and the isolation module connected to other lines have the ability to withstand the transient breaking voltage, the breaking unit is locked and the current is transferred to the energy consumption module for clearing.

Images