Phase unit, active commutation converter and control method, device and system thereof

Abstract

The invention provides a phase unit, an active commutation converter and a control method, device and system thereof, and relates to the technical field of high-voltage direct-current transmission. The phase unit comprises a main branch which comprises an upper bridge arm circuit and a lower bridge arm circuit, the upper bridge arm circuit and the lower bridge arm circuit are connected in series, one end of the upper bridge arm circuit is connected with an anode bus of the main branch, and one end of the lower bridge arm circuit is connected with a cathode bus of the main branch; the auxiliary branch comprises an upper bridge transfer circuit, a lower bridge transfer circuit and a main turn-off circuit, one end of the upper bridge transfer circuit is connected with the upper bridge arm circuit, the other end of the upper bridge transfer circuit is connected with one end of the lower bridge transfer circuit and one end of the main turn-off circuit, and the other end of the lower bridge transfer circuit is connected with the lower bridge arm circuit; the other end of the main turn-off circuit is connected with a common point where the upper bridge arm circuit and the lower bridge arm circuit are connected in series. According to the invention, commutation failure of the high-voltage direct-current power transmission system can be suppressed, and the reliability of the high-voltage direct-current power transmission system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of high voltage direct current transmission, and in particular to a phase unit, an active commutation converter, and a control method, device and system thereof. Background Art

[0002] With economic development and continuous improvement of technology, the number of high-voltage and ultra-high-voltage direct current transmission systems connected to the power grid is gradually increasing, but this also increases the hidden dangers of safe operation of the power grid. For example, when multiple DC lines fail to commutate at the same time in a multi-input DC system, there is a threat to the safe operation of the AC power grid in the corresponding area. In addition, with the increasing proportion of renewable energy power generation in recent years, higher requirements are placed on the stable operation of the DC transmission system and the ability to suppress commutation failures.

[0003] The existing DC transmission technology mainly adopts a grid-commutated converter with a twelve-pulse circuit structure and a voltage source converter with a modular multi-level circuit structure for high-voltage and ultra-high-voltage DC transmission. In the grid-commutated converter with a twelve-pulse circuit structure, each twelve-pulse circuit is composed of two three-phase six-bridge arm bridge circuits connected in series or in parallel, and each bridge arm adopts a single large-capacity thyristor in series; in the voltage source converter with a modular multi-level circuit structure, the modular multi-level circuit is a three-phase six-bridge arm bridge circuit, and each bridge arm adopts a half-bridge sub-module structure or / and a full-bridge sub-module structure in series. In addition, it has become an important research direction of DC transmission technology to solve the commutation failure problem by replacing or adding an auxiliary shutdown circuit with a fully controlled device on the basis of the existing grid-commutated converter to form a controllable shutdown grid-commutated converter.

[0004] However, the existing grid-commutated converter with a twelve-pulse circuit structure has the problem of commutation failure; the existing voltage source converter with a modular multi-level circuit structure has the problems of small device capacity, high cost and large loss; the existing grid-commutated converter with controllable shutdown that uses full-control device replacement to suppress commutation failure has a small device capacity and its reliability needs to be verified; the existing grid-commutated converter with controllable shutdown that adds auxiliary circuits to suppress commutation failure has a complex structure and reduced reliability; the above two types of controllable shutdown grid-commutated converters rely on lightning arresters to absorb energy when forced to shut down, and each bridge arm needs to be equipped with an equal amount of lightning arresters. In the case of a high probability fault such as single-phase grounding, only the lightning arrester of the fault phase will be activated, resulting in a low utilization rate of the lightning arrester. Since the lightning arrester can only absorb energy for a short time, the lightning arrester cannot be activated during steady-state operation, so it is still necessary to rely on the grid commutation voltage for commutation, resulting in the minimum shutdown angle cannot be controlled too small, and still need to consume more reactive power. Summary of the invention

[0005] In order to suppress the occurrence of commutation failure in a high-voltage direct current transmission system, reduce the cost of a controllably shut-down grid commutation converter, improve the reliability of the high-voltage direct current transmission system, and reduce the shut-off angle reference value and reactive power consumed in the commutation process of the grid commutation converter, the present invention provides a phase unit, an active commutation converter, and a control method, device, and system thereof.

[0006] The present invention provides a phase unit, which adopts the following technical solution:

[0007] A phase unit, comprising:

[0008] The main branch includes an upper bridge arm circuit and a lower bridge arm circuit; wherein the upper bridge arm circuit and the lower bridge arm circuit are connected in series, one end of the upper bridge arm circuit is connected to the anode bus of the main branch, and one end of the lower bridge arm circuit is connected to the cathode bus of the main branch;

[0009] An auxiliary branch includes an upper bridge transfer circuit, a lower bridge transfer circuit and a main shutdown circuit; wherein one end of the upper bridge transfer circuit is connected to the upper bridge arm circuit, the other end of the upper bridge transfer circuit is connected to one end of the lower bridge transfer circuit and one end of the main shutdown circuit, the other end of the lower bridge transfer circuit is connected to the lower bridge arm circuit, and the other end of the main shutdown circuit is connected to a common point where the upper bridge arm circuit and the lower bridge arm circuit are connected in series.

[0010] According to some embodiments, the upper bridge arm circuit and the lower bridge arm circuit respectively include a first half-controlled valve and / or a first fully-controlled valve; or, the upper bridge arm circuit and the lower bridge arm circuit respectively include a first half-controlled valve and / or a first fully-controlled valve, a second half-controlled valve; the upper bridge transfer circuit and the lower bridge transfer circuit respectively include a third half-controlled valve and / or a second fully-controlled valve; and the main shutdown circuit includes a third fully-controlled valve.

[0011] According to some embodiments, in the case where the upper bridge arm circuit and the lower bridge arm circuit respectively include a second half-controlled valve, one end of the first half-controlled valve and / or the first fully-controlled valve of the upper bridge arm circuit is connected to the main branch anode bus, the other end of the first half-controlled valve and / or the first fully-controlled valve of the upper bridge arm circuit is connected to one end of the second half-controlled valve and one end of the third half-controlled valve and / or the second fully-controlled valve of the upper bridge transfer circuit, the other end of the second half-controlled valve of the upper bridge arm circuit is connected to one end of the third fully-controlled valve of the main shut-off circuit, and the other end of the third fully-controlled valve of the main shut-off circuit is connected to the other end of the third half-controlled valve and / or the second fully-controlled valve of the upper bridge transfer circuit;

[0012] One end of the first half-controlled valve and / or the first fully-controlled valve of the lower bridge arm circuit is connected to the cathode bus of the main branch, the other end of the first half-controlled valve and / or the first fully-controlled valve of the lower bridge arm circuit is connected to one end of the second half-controlled valve and one end of the third half-controlled valve and / or the second fully-controlled valve of the lower bridge transfer circuit, the other end of the second half-controlled valve of the lower bridge arm circuit is connected to one end of the third fully-controlled valve of the main shut-off circuit, and the other end of the third fully-controlled valve of the main shut-off circuit is connected to the other end of the third half-controlled valve and / or the second fully-controlled valve of the lower bridge transfer circuit.

[0013] According to some embodiments, when the upper bridge arm circuit and the lower bridge arm circuit do not include a second half-controlled valve,

[0014] One end of the first half-controlled valve and / or the first fully-controlled valve of the upper bridge arm circuit is connected to the main branch anode bus, the other end of the first half-controlled valve and / or the first fully-controlled valve of the upper bridge arm circuit is connected to one end of the third half-controlled valve and / or the second fully-controlled valve of the upper bridge transfer circuit and one end of the third fully-controlled valve of the main shut-off circuit, and the other end of the third half-controlled valve and / or the second fully-controlled valve of the upper bridge transfer circuit is connected to the other end of the third fully-controlled valve of the main shut-off circuit;

[0015] One end of the first half-controlled valve and / or the first fully-controlled valve of the lower bridge arm circuit is connected to the cathode bus of the main branch, the other end of the first half-controlled valve and / or the first fully-controlled valve of the lower bridge arm circuit is connected to one end of the third half-controlled valve and / or the second fully-controlled valve of the lower bridge transfer circuit and one end of the third fully-controlled valve of the main shut-off circuit, and the other end of the third half-controlled valve and / or the second fully-controlled valve of the lower bridge transfer circuit is connected to the other end of the third fully-controlled valve of the main shut-off circuit.

[0016] According to some embodiments, the first half-controlled valve and / or the first fully-controlled valve and / or the second half-controlled valve and / or the third half-controlled valve and / or the second fully-controlled valve and / or the third fully-controlled valve are connected in parallel with a lightning arrester.

[0017] According to some embodiments, the first half-controlled valve, the second half-controlled valve, and the third half-controlled valve include at least one of a one-way half-controlled switch and a two-way half-controlled switch; the first full-controlled valve and the second full-controlled valve include at least one of a one-way full-controlled switch, a two-way full-controlled switch, and a sub-module series switch; the third full-controlled valve includes at least one of a two-way full-controlled switch and a sub-module series switch.

[0018] According to some embodiments, the unidirectional half-controlled switch is composed of semiconductor devices that can be controlled to turn on but not controlled to turn off connected in series, and the semiconductor devices that can be controlled to turn on but not controlled to turn off include but are not limited to thyristors;

[0019] The bidirectional half-controlled switch is composed of semiconductor devices that can be controlled to be turned on but not controlled to be turned off, which are connected in anti-parallel and then in series. The semiconductor devices that can be controlled to be turned on but not controlled to be turned off include but are not limited to thyristors;

[0020] The unidirectional fully controlled switch is composed of semiconductor devices with unidirectional shutoff capability connected in series, and the semiconductor devices with unidirectional shutoff capability include but are not limited to insulated gate bipolar transistors and integrated gate-commutated thyristors;

[0021] The bidirectional fully-controlled switch is composed of semiconductor devices with bidirectional shutoff capability connected in series, and the semiconductor devices with bidirectional shutoff capability include but are not limited to anti-parallel reverse-resistance integrated gate-commutated thyristors and series-connected insulated gate bipolar transistor modules;

[0022] The submodule series switch is composed of submodules connected in series, and the submodules include but are not limited to half-bridge submodules, full-bridge submodules, quasi-full-bridge submodules, and clamped twin submodules. The switching devices of the half-bridge submodules, full-bridge submodules, quasi-full-bridge submodules or clamped twin submodules include but are not limited to insulated gate bipolar transistors and integrated gate-commutated thyristors.

[0023] According to some embodiments, the main shutdown circuit further includes a fourth half-controlled valve, and the fourth half-controlled valve is connected in parallel with the third full-controlled valve; the fourth half-controlled valve includes at least one of a one-way half-controlled switch and a two-way half-controlled switch.

[0024] The present invention provides an active commutation converter, which adopts the following technical solution:

[0025] An active commutation converter comprises: at least one phase unit as described above; or,

[0026] at least one of said phase units and an auxiliary shut-down circuit; or,

[0027] A main shut-off circuit of at least one of the main branches and at least one of the auxiliary branches; wherein one end of the main shut-off circuit of at least one of the auxiliary branches serves as a phase output end, and the other end of the main shut-off circuit of at least one of the auxiliary branches is connected to a common point where an upper bridge arm circuit and a lower bridge arm circuit of at least one of the main branches are connected in series, and the upper bridge arm circuit and the lower bridge arm circuit of at least one of the main branches respectively include a first full-control valve; or,

[0028] A main shut-off circuit and an auxiliary shut-off circuit of at least one of the main branches and at least one of the auxiliary branches; wherein one end of the main shut-off circuit of at least one of the auxiliary branches is used as a phase output end, and the other end of the main shut-off circuit of at least one of the auxiliary branches is connected to a common point where an upper bridge arm circuit and a lower bridge arm circuit of at least one of the main branches are connected in series;

[0029] The circuit constructed by the auxiliary shutdown circuit is connected in parallel with the upper bridge arm circuit or the lower bridge arm circuit of at least one of the main branches and the circuit constructed by the main shutdown circuit of at least one of the auxiliary branches; or, the auxiliary shutdown circuit is connected in parallel with the at least one phase unit.

[0030] According to some embodiments, the main branch anode bus serves as a positive input terminal, one end of the main shutdown circuit of the auxiliary branch serves as a phase output terminal, and the main branch cathode bus serves as a negative input terminal.

[0031] According to some embodiments, one end of the auxiliary shutdown circuit is connected to the anode bus of the main branch of the active commutation converter, and the other end of the auxiliary shutdown circuit is connected to the cathode bus of the main branch of the active commutation converter.

[0032] According to some embodiments, the auxiliary shutdown circuit and the main branch anode busbar and the main branch cathode busbar of the active commutation converter are connected via an isolating switch and / or a knife switch.

[0033] According to some embodiments, when the circuit constructed by the auxiliary shut-off circuit is connected in parallel with the upper bridge arm circuit or the lower bridge arm circuit of at least one of the main branches and the circuit constructed by the main shut-off circuit of at least one of the auxiliary branches, the auxiliary shut-off circuit includes a fourth fully-controlled valve; or, the auxiliary shut-off circuit includes a fourth fully-controlled valve and a fifth half-controlled valve; the fourth fully-controlled valve and the fifth half-controlled valve are connected in series; or,

[0034] When the auxiliary shutoff circuit is connected in parallel with the at least one phase unit, the auxiliary shutoff circuit includes a fifth fully-controlled valve; or, the auxiliary shutoff circuit includes a fifth fully-controlled valve and a sixth half-controlled valve; the fifth fully-controlled valve and the sixth half-controlled valve are connected in series.

[0035] According to some embodiments, when the circuit constructed by the auxiliary shutdown circuit is connected in parallel with the upper bridge arm circuit or the lower bridge arm circuit of at least one of the main branches and the circuit constructed by the main shutdown circuit of at least one of the auxiliary branches, the auxiliary shutdown circuit also includes a seventh half-controlled valve or a first uncontrolled valve; the seventh half-controlled valve or the first uncontrolled valve, the fourth fully-controlled valve and the fifth half-controlled valve are connected in series, and the circuit after the series connection is connected in parallel with the upper bridge arm circuit or the lower bridge arm circuit, or the circuit after the series connection is connected in parallel with the upper bridge arm circuit or the lower bridge arm circuit and the circuit in series with the main shutdown circuit of at least one of the auxiliary branches.

[0036] According to some embodiments, when the auxiliary shutoff circuit is connected in parallel with the at least one phase unit, the first half-controlled valve and the second half-controlled valve include bidirectional half-controlled switches.

[0037] According to some embodiments, when the circuit constructed by the auxiliary shutoff circuit is connected in parallel with the upper bridge arm circuit or the lower bridge arm circuit of at least one of the main branches and the circuit constructed by the main shutoff circuit of at least one of the auxiliary branches, the upper bridge arm circuit and / or the lower bridge arm circuit share the fourth full-control valve and / or the fifth half-control valve of the auxiliary shutoff circuit;

[0038] In the case where the auxiliary shutoff circuit is connected in parallel with the at least one phase unit, the upper bridge arm circuit and the lower bridge arm circuit share the fifth fully-controlled valve and / or the sixth half-controlled valve of the auxiliary shutoff circuit.

[0039] According to some embodiments, the fifth half-controlled valve and the sixth half-controlled valve include a one-way half-controlled switch, the fourth fully-controlled valve and the fifth fully-controlled valve include at least one of a one-way fully-controlled switch, a two-way fully-controlled switch, and a sub-module series switch, and the first uncontrolled valve includes an uncontrolled switch; the uncontrolled switch is composed of a series connection of semiconductor devices for uncontrolled opening and closing, and the uncontrolled opening and closing semiconductor devices include but are not limited to diodes.

[0040] According to some embodiments, the fifth half-controlled valve, and / or the fourth full-controlled valve, and / or the fifth full-controlled valve, and / or the sixth half-controlled valve are connected in parallel with a lightning arrester.

[0041] The present invention provides an active commutation converter control method, which adopts the following technical solution:

[0042] A control method for an active commutation converter, characterized in that it is used to control the active commutation converter, comprising:

[0043] In the case of obtaining the operating parameter information of the active commutation converter, generating the inverter state control information based on the parameter information, and controlling the main branch of the bridge arm circuit to operate in the inverter state based on the inverter state control information;

[0044] When the active commutation converter includes at least one phase unit and / or an auxiliary shut-off circuit, and when the shut-off angle reference value of the active commutation converter is less than the minimum shut-off angle setting or commutation fault information is obtained, a first circuit conduction instruction and a first negative pressure control information are generated, and the transfer circuit in the auxiliary branch corresponding to the commutation bridge arm is controlled to be turned on based on the first circuit conduction instruction, and the main shut-off circuit of the auxiliary branch corresponding to the commutation bridge arm is controlled to present a negative pressure based on the first negative pressure control information; when the second half-controlled valve of the commutation bridge arm of the main branch resumes shutdown, a first circuit shut-off instruction is generated to control the main shut-off circuit of the auxiliary branch to shut down; or, when the active commutation converter includes the main shut-off circuits of the main branch and the auxiliary branch, and when the shut-off angle reference value is less than the minimum shut-off angle setting or commutation fault information is obtained, a first circuit shut-off instruction is generated to control the main shut-off circuit of the auxiliary branch to shut down.

[0045] According to some embodiments, when the active commutation converter operates normally, the turn-off angle reference value is set to be less than the minimum turn-off angle setting; when the turn-off angle reference value is obtained to be less than the minimum turn-off angle setting and the second half-controlled valve of the commutation bridge arm of the main branch is restored to shutdown, a first circuit shutdown instruction is generated to control the third full-controlled valve corresponding to the commutation bridge arm to shut down.

[0046] According to some embodiments, before controlling the main shutdown circuit of the auxiliary branch to be shut down, second negative voltage control information is generated, and based on the second negative voltage control information, the main shutdown circuit of the auxiliary branch corresponding to the bridge arm to be switched is controlled to present a negative voltage.

[0047] According to some embodiments, when the capacitor voltage of the submodule of the third fully-controlled valve of the main shutdown circuit is lower than the rated value and exceeds the first threshold, and the second half-controlled valve of the phase-changing bridge arm of the main branch resumes shutdown, a first circuit shutdown instruction is generated in advance; or / and the number of submodules of the third fully-controlled valve of the main shutdown circuit is increased; or / and a first circuit conduction instruction and a first negative pressure control information are generated in advance; the first threshold value range is 0.01 to 0.6 times the rated capacitor voltage.

[0048] According to some embodiments, when the sub-module capacitor voltage of the third fully-controlled valve of the main shutdown circuit is greater than or equal to the rated value and exceeds the second threshold, and the first half-controlled valve of the phase-changing bridge arm of the main branch resumes shutdown, the generation of the first circuit shutdown instruction is delayed; or / and the number of sub-modules of the third fully-controlled valve of the main shutdown circuit is reduced; or / and the generation of the first circuit conduction instruction and the first negative pressure control information is delayed and shortened; the second threshold value range is 0.01 to 0.6 times the rated capacitor voltage.

[0049] According to some embodiments, controlling the main shut-off circuit to present a negative pressure is achieved by controlling a switch device in a submodule of the third full-control valve to be turned on so that the submodule presents a capacitive negative pressure in a current flow direction.

[0050] According to some embodiments, the recovery and shutdown of the second half-controlled valve of the commutation bridge arm of the main branch is determined according to the reverse recovery time of the second half-controlled valve, and the reverse recovery time is greater than or equal to the reverse recovery time of the thyristor included in the second half-controlled valve.

[0051] According to some embodiments, in case of overpressure or failure of the third fully-controlled valve, the second half-controlled valve or the fourth half-controlled valve of the same phase unit of the third fully-controlled valve is controlled to be conductive.

[0052] According to some embodiments, the method further comprises:

[0053] When the upper bridge arm circuit and the lower bridge arm circuit respectively include a first fully-controlled valve, and phase switching fault information is obtained, and the main shutdown circuit cannot provide sufficient phase switching voltage, a second circuit shutdown instruction is generated, and the first fully-controlled valve is controlled to be shut down based on the second circuit shutdown instruction.

[0054] According to some embodiments, when the upper bridge transfer circuit and the lower bridge transfer circuit respectively include a second fully controlled valve, the method further includes:

[0055] When the commutation fault information is obtained and the main shut-off circuit cannot provide sufficient commutation voltage, a third circuit shut-off instruction is generated, and the second full-control valve is controlled to be shut off based on the third circuit shut-off instruction.

[0056] According to some embodiments, when the active commutation converter further includes an auxiliary shutdown circuit, the method further includes:

[0057] When the commutation fault information is obtained and the main shutdown circuit cannot provide sufficient commutation voltage, a second circuit conduction instruction is generated, and the auxiliary shutdown circuit corresponding to the commutation bridge arm is controlled to be turned on based on the second circuit conduction instruction. When the first half-controlled valve and / or the second half-controlled valve of the commutation bridge arm of the main branch resumes shutdown, a fourth circuit shutdown instruction is generated to control the auxiliary shutdown circuit to be turned off.

[0058] According to some embodiments, the actively commutated converter controls voltage and frequency using a grid-connected control method.

[0059] According to some embodiments, when the active commutation converter also includes an auxiliary shutdown circuit, the auxiliary shutdown circuit and the main branch anode bus and the main branch cathode bus of the main control forced commutation converter are connected through an isolating switch and / or a knife switch, and in the event of a fault in the auxiliary shutdown circuit, the isolating switch and / or the knife switch are disconnected.

[0060] The present invention provides an active commutation converter control device, which adopts the following technical solution:

[0061] An active commutation converter control device, used for controlling the active commutation converter, comprising:

[0062] A first control module, configured to, when obtaining operating parameter information of the active commutation converter, generate inverter state control information based on the parameter information, and control the main branch to operate in an inverter state based on the inverter state control information;

[0063] The second control module is used to generate a first circuit conduction instruction and a first negative pressure control information when the active commutation converter includes at least one phase unit and a shutdown angle reference value is obtained that is less than a minimum shutdown angle setting or commutation fault information, and control the transfer circuit in the auxiliary branch corresponding to the commutation bridge arm to be turned on based on the first circuit conduction instruction, and control the main shutdown circuit of the auxiliary branch corresponding to the commutation bridge arm to present a negative pressure based on the first negative pressure control information; generate a first circuit shutdown instruction when the second half-controlled valve of the commutation bridge arm of the main branch resumes shutdown, and control the main shutdown circuit of the auxiliary branch to be turned off; or, when the active commutation converter includes the main shutdown circuits of the main branch and the auxiliary branch, and a shutdown angle reference value is obtained that is less than a minimum shutdown angle setting or commutation fault information, generate a first circuit shutdown instruction to control the main shutdown circuit of the auxiliary branch to be turned off.

[0064] The present invention provides a high-voltage direct current power transmission system, comprising the active commutation converter.

[0065] According to some embodiments, the high voltage direct current transmission system is a two-terminal direct current transmission system or a multi-terminal direct current transmission system, and the two-terminal direct current transmission system or the multi-terminal direct current transmission system respectively includes a monopolar direct current transmission system, a bipolar direct current transmission system or a back-to-back direct current system.

[0066] According to some embodiments, some or all of the converters that need to be inverted in the two-terminal DC power transmission system or the multi-terminal DC power transmission system adopt the active commutation converter.

[0067] In summary, the present invention includes the following beneficial technical effects:

[0068] When the turn-off angle reference value is small or the commutation failure may occur due to the AC system fault, the main turn-off circuit is controlled to present a negative pressure, the corresponding transfer circuit is turned on to form a flow in parallel with the second half-controlled valve of the main branch commutation bridge arm, the current is transferred to the auxiliary branch, and the main turn-off circuit of the auxiliary branch is controlled to be turned off to realize the turn-off of the commutation bridge arm; if the main turn-off circuit cannot provide sufficient turn-off voltage, the first full-controlled valve of the main branch is controlled to be turned off, or the auxiliary turn-off circuit is controlled to be turned on first, and after the current of the first half-controlled valve of the main branch is transferred and restored to be turned off, the auxiliary turn-off circuit is controlled to be turned off to realize the turn-off of the commutation bridge arm, effectively suppressing the commutation failure of the active commutation converter, realizing the controllable turn-off of the active commutation converter, and improving the reliability of the high-voltage direct current transmission system; at the same time, the turn-off angle reference value can be reduced by using the continuous turn-off capability of the main turn-off circuit, and the reactive power consumption can be reduced; compared with the prior art, the circuit structure of the present invention is simple, the reactive compensation equipment can be reduced, the cost of the high-voltage direct current transmission system with controllable turn-off capability is reduced, and the reliability of the system is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 This is one of the phase unit schematic diagrams of an embodiment of the present invention;

[0070] Figure 2 This is the second schematic diagram of the phase unit of the embodiment of the present invention;

[0071] Figure 3A , Figure 3B , Figure 3C , Figure 3D , Figure 3E , Figure 3F , Figure 3G , Figure 3H , Fig. 3I , Figure 3J , Figure 3K , Figure 3L as well as Figure 3M Schematic diagram of the valve structure of an embodiment of the present invention;

[0072] Figure 4 This is one of the schematic diagrams of the active commutation converter according to the embodiment of the present invention;

[0073] Figure 5 This is the second schematic diagram of the active commutation converter according to the embodiment of the present invention;

[0074] Figure 6 This is the third schematic diagram of the active commutation converter according to the embodiment of the present invention;

[0075] Figure 7 This is the fourth schematic diagram of the active commutation converter according to the embodiment of the present invention;

[0076] Figure 8 This is the fifth schematic diagram of the active commutation converter according to the embodiment of the present invention;

[0077] Fig. 9 This is the sixth schematic diagram of the active commutation converter according to the embodiment of the present invention;

[0078] Fig.10 This is the seventh schematic diagram of the active commutation converter according to the embodiment of the present invention;

[0079] Fig.11 It is one of the circuit diagrams of an active commutation converter including a valve structure according to an embodiment of the present invention;

[0080] Fig.12 This is the second circuit diagram of the active commutation converter including the valve structure according to the embodiment of the present invention;

[0081] Fig.13 This is the third circuit diagram of the active commutation converter including the valve structure according to the embodiment of the present invention;

[0082] Fig.14 This is the fourth circuit diagram of the active commutation converter including the valve structure according to the embodiment of the present invention;

[0083] Fig.15 This is the fifth circuit diagram of the active commutation converter including the valve structure according to the embodiment of the present invention;

[0084] Fig.16 This is the sixth circuit diagram of the active commutation converter including the valve structure according to the embodiment of the present invention;

[0085] Fig.17 This is the seventh circuit diagram of the active commutation converter including the valve structure according to the embodiment of the present invention;

[0086] Fig.18 This is the eighth circuit diagram of the active commutation converter including the valve structure according to the embodiment of the present invention;

[0087] Fig.19 This is the ninth circuit diagram of the active commutation converter including the valve structure according to the embodiment of the present invention;

[0088] Fig. 20 is a block diagram of a control method for an active commutation converter according to an embodiment of the present invention;

[0089] Fig.21 is a flow chart of a control method for an active commutation converter according to an embodiment of the present invention;

[0090] Fig. 22 is a block diagram of a control device for an active commutation converter according to an embodiment of the present invention;

[0091] Fig.23 The invention discloses a high voltage direct current transmission system including an active commutation converter.

[0092] Explanation of the accompanying drawings: 1. upper bridge arm circuit; 2. lower bridge arm circuit; 3. upper bridge transfer circuit; 4. lower bridge transfer circuit; 5. main shutdown circuit; 6. first auxiliary shutdown circuit; 7. second auxiliary shutdown circuit; 8. first grid phase-commutating converter; 9. second grid phase-commutating converter; 10. first converter transformer; 11. second converter transformer; 12. first AC system; 13. DC line; 14. first active phase-commutating converter; 15. second active phase-commutating converter; 16. third converter transformer; 17. fourth converter transformer; 18. second AC system; 201. first control module; 202. second control module. DETAILED DESCRIPTION

[0093] The following is combined with Figure 1-23 The present invention is described in further detail.

[0094] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the following will gather the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0095] The embodiment of the present invention provides a phase unit, comprising: a main branch and an auxiliary branch, wherein the main branch comprises an upper bridge arm circuit and a lower bridge arm circuit; wherein the upper bridge arm circuit and the lower bridge arm circuit are connected in series, one end of the upper bridge arm circuit is connected to an anode bus of the main branch, and one end of the lower bridge arm circuit is connected to a cathode bus of the main branch;

[0096] The auxiliary branch includes an upper bridge transfer circuit, a lower bridge transfer circuit and a main shutdown circuit; wherein one end of the upper bridge transfer circuit is connected to the upper bridge arm circuit, the other end of the upper bridge transfer circuit is connected to one end of the lower bridge transfer circuit and one end of the main shutdown circuit, the other end of the lower bridge transfer circuit is connected to the lower bridge arm circuit, and the other end of the main shutdown circuit is connected to a common point where the upper bridge arm circuit and the lower bridge arm circuit are connected in series.

[0097] The upper bridge arm circuit and the lower bridge arm circuit respectively include the first half-controlled valve and / or the first fully-controlled valve; or, the upper bridge arm circuit and the lower bridge arm circuit respectively include the first half-controlled valve and / or the first fully-controlled valve and the second half-controlled valve; the upper bridge transfer circuit and the lower bridge transfer circuit respectively include the third half-controlled valve and / or the second fully-controlled valve; the main shutdown circuit includes the third fully-controlled valve.

[0098] When the upper bridge arm circuit and the lower bridge arm circuit respectively include the second half-controlled valve, one end of the first half-controlled valve and / or the first fully-controlled valve of the upper bridge arm circuit is connected to the anode bus of the main branch, the other end of the first half-controlled valve and / or the first fully-controlled valve of the upper bridge arm circuit is connected to one end of the second half-controlled valve and one end of the third half-controlled valve and / or the second fully-controlled valve of the upper bridge transfer circuit, the other end of the second half-controlled valve of the upper bridge arm circuit is connected to one end of the third fully-controlled valve of the main shut-off circuit, and the other end of the third fully-controlled valve of the main shut-off circuit is connected to the other end of the third half-controlled valve and / or the second fully-controlled valve of the upper bridge transfer circuit.

[0099] One end of the first half-controlled valve and / or the first fully-controlled valve of the lower bridge arm circuit is connected to the cathode bus of the main branch, the other end of the first half-controlled valve and / or the first fully-controlled valve of the lower bridge arm circuit is connected to one end of the second half-controlled valve and one end of the third half-controlled valve and / or the second fully-controlled valve of the lower bridge transfer circuit, the other end of the second half-controlled valve of the lower bridge arm circuit is connected to one end of the third fully-controlled valve of the main shut-off circuit, and the other end of the third fully-controlled valve of the main shut-off circuit is connected to the other end of the third half-controlled valve and / or the second fully-controlled valve of the lower bridge transfer circuit.

[0100] Reference Figure 1 The main branch includes: an upper bridge arm circuit 1 and a lower bridge arm circuit 2, the upper bridge arm circuit 1 and the lower bridge arm circuit 2 are connected in series; one end of the upper bridge arm circuit 1 is connected to the main branch anode bus P1, and one end of the lower bridge arm circuit 2 is connected to the main branch cathode bus N1.

[0101] The auxiliary branch includes: an upper bridge transfer circuit 3, a lower bridge transfer circuit 4 and a main shutdown circuit 5, one end of the upper bridge transfer circuit 3 is connected to the upper bridge arm circuit 1, the other end of the upper bridge transfer circuit 3 is connected to one end of the lower bridge transfer circuit 4 and one end of the main shutdown circuit 5, the other end of the lower bridge transfer circuit 4 is connected to the lower bridge arm circuit 2, and the other end of the main shutdown circuit 5 is connected to a common point where the upper bridge arm circuit 1 and the lower bridge arm circuit 2 are connected in series.

[0102] In some embodiments, reference Figure 1 The upper bridge arm circuit 1 includes a first half-controlled valve and / or a first fully-controlled valve V41, a second half-controlled valve V42; the lower bridge arm circuit 2 includes a first half-controlled valve and / or a first fully-controlled valve V11, a second half-controlled valve V12; the upper bridge transfer circuit 3 includes a third half-controlled valve and / or a second fully-controlled valve V43; the lower bridge transfer circuit 4 includes a third half-controlled valve and / or a second fully-controlled valve V13; the main shutdown circuit includes a third fully-controlled valve V410.

[0103] One end of the first half-controlled valve and / or the first fully-controlled valve V41 of the upper bridge arm circuit 1 is connected to the main branch anode bus P1, and the other end of the first half-controlled valve and / or the first fully-controlled valve V41 of the upper bridge arm circuit 1 is connected to one end of the second half-controlled valve V42 and one end of the third half-controlled valve and / or the second fully-controlled valve V43 of the upper bridge transfer circuit 3; the other end of the second half-controlled valve V42 of the upper bridge arm circuit 1 is connected to one end of the third fully-controlled valve V410 of the main shutdown circuit 5 and one end of the second half-controlled valve V12 of the lower bridge arm circuit 2, and serves as the phase output end; the other end of the third half-controlled valve and / or the second fully-controlled valve V43 of the upper bridge transfer circuit 3 is connected to the other end of the third fully-controlled valve V410 of the main shutdown circuit 5.

[0104] One end of the first half-controlled valve and / or the first fully-controlled valve V11 of the lower bridge arm circuit 2 is connected to the cathode bus N1 of the main branch, the other end of the first half-controlled valve and / or the first fully-controlled valve V11 of the lower bridge arm circuit 2 is connected to one end of the second half-controlled valve V12 and one end of the third half-controlled valve and / or the second fully-controlled valve V13 of the lower bridge transfer circuit 4, the other end of the second half-controlled valve V12 of the lower bridge arm circuit 2 is connected to one end of the second half-controlled valve V42 of the upper bridge arm circuit 1 and one end of the third fully-controlled valve V410 of the main shutdown circuit 5, and serves as the phase output end; the other end of the third half-controlled valve and / or the second fully-controlled valve V13 of the lower bridge transfer circuit 4 is connected to one end of the third half-controlled valve and / or the second fully-controlled valve V43 of the upper bridge transfer circuit 3 and the other end of the third fully-controlled valve V410 of the main shutdown circuit 5.

[0105] In some embodiments, when the upper bridge arm circuit and the lower bridge arm circuit do not include the second half-controlled valve respectively, one end of the first half-controlled valve and / or the first fully-controlled valve of the upper bridge arm circuit is connected to the anode bus of the main branch, the other end of the first half-controlled valve and / or the first fully-controlled valve of the upper bridge arm circuit is connected to one end of the third half-controlled valve and / or the second fully-controlled valve of the upper bridge transfer circuit and one end of the third fully-controlled valve of the main shut-off circuit, and the other end of the third half-controlled valve and / or the second fully-controlled valve of the upper bridge transfer circuit is connected to the other end of the third fully-controlled valve of the main shut-off circuit.

[0106] One end of the first half-controlled valve and / or the first fully-controlled valve of the lower bridge arm circuit is connected to the cathode bus of the main branch, the other end of the first half-controlled valve and / or the first fully-controlled valve of the lower bridge arm circuit is connected to one end of the third half-controlled valve and / or the second fully-controlled valve of the lower bridge transfer circuit and one end of the third fully-controlled valve of the main shut-off circuit, and the other end of the third half-controlled valve and / or the second fully-controlled valve of the lower bridge transfer circuit is connected to the other end of the third fully-controlled valve of the main shut-off circuit.

[0107] In some embodiments, reference Figure 2The upper bridge arm circuit 1 includes a first half-controlled valve and / or a first fully-controlled valve V41; the lower bridge arm circuit 2 includes a first half-controlled valve and / or a first fully-controlled valve V11; the upper bridge transfer circuit 3 includes a third half-controlled valve and / or a second fully-controlled valve V43; the lower bridge transfer circuit 4 includes a third half-controlled valve and / or a second fully-controlled valve V13; and the main shutdown circuit includes a third fully-controlled valve V410.

[0108] One end of the first half-controlled valve and / or the first fully-controlled valve V41 of the upper bridge arm circuit 1 is connected to the main branch anode bus P1, and the other end of the first half-controlled valve and / or the first fully-controlled valve V41 of the upper bridge arm circuit 1 is connected to one end of the third fully-controlled valve V410 of the main shutdown circuit 5, one end of the third half-controlled valve and / or the second fully-controlled valve V43 of the upper bridge transfer circuit 3, and one end of the first half-controlled valve and / or the first fully-controlled valve V11 of the lower bridge arm circuit 2; the other end of the third fully-controlled valve V410 of the main shutdown circuit 5 is connected to the other end of the third half-controlled valve and / or the second fully-controlled valve V43 of the upper bridge transfer circuit 3 and one end of the third half-controlled valve and / or the second fully-controlled valve V13 of the lower bridge transfer circuit 4, and serves as the phase output end.

[0109] One end of the first half-controlled valve and / or the first fully-controlled valve V11 of the lower bridge arm circuit 2 is connected to the cathode bus N1 of the main branch, and the other end of the first half-controlled valve and / or the first fully-controlled valve V11 of the lower bridge arm circuit 2 is connected to one end of the first half-controlled valve and / or the first fully-controlled valve V41 of the upper bridge arm circuit 1, one end of the third half-controlled valve and / or the second fully-controlled valve V13 of the lower bridge transfer circuit 4, and one end of the third fully-controlled valve V410 of the main shutdown circuit 5; the other end of the third half-controlled valve and / or the second fully-controlled valve V13 of the lower bridge transfer circuit 4 is connected to one end of the third half-controlled valve and / or the second fully-controlled valve V43 of the upper bridge transfer circuit 3 and the other end of the third fully-controlled valve V410 of the main shutdown circuit 5, and serves as the phase output end.

[0110] The third half-controlled valve and / or the second fully-controlled valve V43 of the upper bridge transfer circuit 3 and the third half-controlled valve and / or the second fully-controlled valve V13 of the lower bridge transfer circuit 4 are in parallel and can be integrated into one valve, using a bidirectional half-controlled switch or a bidirectional fully-controlled switch.

[0111] Figure 2 The circuit shown is Figure 1 In comparison, the first half-controlled valve and / or the first fully-controlled valve V41 of the upper bridge arm circuit 1 and the first half-controlled valve and / or the first fully-controlled valve V11 of the lower bridge arm circuit 2 need to withstand the voltage of the entire bridge arm, and the converter efficiency will be reduced.

[0112] In some embodiments, the main shutoff circuit further includes a fourth half-controlled valve, and the fourth half-controlled valve and the third full-controlled valve are connected in parallel.

[0113] In some embodiments, the first half-controlled valve, the second half-controlled valve, the third half-controlled valve, and the fourth half-controlled valve respectively include at least one of a one-way half-controlled switch and a two-way half-controlled switch, the first full-controlled valve and the second full-controlled valve respectively include at least one of a one-way full-controlled switch, a two-way full-controlled switch, and a sub-module series switch, and the third full-controlled valve includes at least one of a two-way full-controlled switch and a sub-module series switch.

[0114] In some embodiments, a unidirectional half-controlled switch is composed of semiconductor devices that can be controlled to turn on but not to turn off connected in series, and the semiconductor devices that can be controlled to turn on but not to turn off include but are not limited to thyristors; a bidirectional half-controlled switch is composed of semiconductor devices that can be controlled to turn on but not to turn off connected in anti-parallel and then connected in series, and the semiconductor devices that can be controlled to turn on but not to turn off include but are not limited to thyristors; a unidirectional fully-controlled switch is composed of switch devices with unidirectional turn-off capability connected in series, and the switch devices with unidirectional turn-off capability include but are not limited to insulated gate bipolar transistors, integrated gate commutated transistors, etc. Thyristor; a bidirectional fully-controlled switch is composed of switch devices with bidirectional shutoff capability connected in series, and the above-mentioned switch devices with bidirectional shutoff capability include but are not limited to anti-parallel reverse-blocking integrated gate-commutated thyristors and reverse-series insulated gate bipolar transistor modules; a sub-module series switch is composed of sub-modules connected in series, and the sub-modules are not limited to half-bridge sub-modules, full-bridge sub-modules, quasi-full-bridge sub-modules or clamped twin sub-modules, and the switch devices of the above-mentioned half-bridge sub-modules, full-bridge sub-modules, quasi-full-bridge sub-modules or clamped twin sub-modules include but are not limited to insulated gate bipolar transistors and integrated gate-commutated thyristors.

[0115] In some embodiments, the fully-controlled switch includes at least one fully-controlled device connected in series, and the fully-controlled device includes at least one of IGCT (Integrated Gate Commutated Thyristors), reverse-blocking IGCT, IGBT (Insulated Gate Bipolar Transistor), GTO (Gate Turn-Off Thyristor), and MOSFET (Metal Oxide Semiconductor Field Effect Transistor); the half-controlled switch includes at least one half-controlled device connected in series, and the half-controlled device includes a thyristor; the uncontrolled switch includes at least one uncontrolled device connected in series, and the uncontrolled device includes a diode.

[0116] In some embodiments, reference Figure 3A The uncontrolled switch includes a diode D1 connected in series, which cannot be controlled to be turned on and off, and has a unidirectional current-carrying capability and a unidirectional blocking voltage capability; refer to Figure 3BThe unidirectional half-controlled switch includes a thyristor T1 connected in series, which can only control the opening and cannot control the closing, and has a unidirectional current-carrying capacity and a bidirectional blocking voltage capacity. Optionally, the unidirectional half-controlled switch is composed of a thyristor and a diode connected in series; refer to Figure 3C The bidirectional half-controlled switch is composed of anti-parallel thyristors T1 connected in series. It can only control the opening but not the closing. It has bidirectional current-carrying capacity and bidirectional blocking voltage capacity. Figure 3D The anti-parallel uncontrolled switch and the unidirectional half-controlled switch are composed of an anti-parallel thyristor T1 and a diode D1 connected in series. They can only be turned on in one direction but not turned off. They have bidirectional current-carrying capacity and unidirectional blocking voltage capacity. Figure 3E The unidirectional fully controlled switch includes an IGBT module connected in series, the IGBT module includes an IGBT (T2) and a diode D2 connected in anti-parallel thereto, which is only unidirectionally controlled to be turned on and off, and has bidirectional current flow and unidirectional blocking voltage capabilities; refer to Figure 3F The unidirectional fully controlled switch includes a reverse resistance type IGCT (T3) connected in series, which is only controlled to be turned on and off in one direction, and has the capability of unidirectional current flow and bidirectional voltage blocking; refer to Figure 3G The unidirectional fully controlled switch includes an IGBT module and a diode D1 connected in series, which can only be turned on and off in one direction, and has the capability of unidirectional current flow and bidirectional voltage blocking; Figure 3H The unidirectional fully controlled switch includes a reverse-resistance IGCT (T3) and a thyristor T1 connected in anti-parallel and then in series. It has a bidirectional control opening and a unidirectional control closing, and has a bidirectional current passing and bidirectional blocking voltage capability; refer to Fig. 3I The bidirectional fully controlled switch includes a forward IGBT module and a reverse IGBT module connected in series, which can be bidirectionally controlled to be turned on and off, and has a bidirectional current-carrying capacity and a bidirectional blocking voltage capacity; refer to Figure 3J The bidirectional fully controlled switch includes a series circuit of reverse-resistance type IGCT (T3) connected in anti-parallel, which can be bidirectionally controlled to be turned on and off, and has bidirectional current-carrying capacity and bidirectional blocking voltage capacity; refer to Figure 3K The sub-module series switch includes a half-bridge sub-module connected in series, the half-bridge sub-module includes two IGBT modules M1, M2 and a capacitor C1, the connection point of the two IGBT modules M1, M2 serves as the positive electrode of the half-bridge sub-module, wherein the other end of the IGBT module M2 serves as the negative electrode of the half-bridge sub-module, the half-bridge sub-modules are connected in series, and they only control opening and closing in one direction, and have bidirectional current-carrying capacity and unidirectional blocking voltage capacity; refer to Figure 3LThe sub-module series switch includes a full-bridge sub-module connected in series. The full-bridge sub-module includes four IGBT modules M3, M4, M5, M6 and a capacitor C1. The IGBT modules M3 and M4 are connected in series and then connected in parallel with M5 and M6, and are also connected in parallel with the capacitor C1. The connection point of the IGBT modules M3 and M4 connected in series serves as the positive electrode of the full-bridge sub-module, and the connection point of the IGBT modules M5 and M6 connected in series serves as the negative electrode of the sub-module. The full-bridge sub-modules are connected in series and can be bidirectionally controlled to be turned on and off, and have bidirectional current-carrying capacity and bidirectional blocking voltage capacity. Figure 3M The sub-module series switch includes a quasi-full-bridge sub-module connected in series, and the quasi-full-bridge sub-module includes two IGBT modules M7 and M8, two diodes D3 and D4 and a capacitor C1. The diode D3 and the IGBT module M7 are connected in series, and the diode D4 and the IGBT module M8 are connected in series and then connected in parallel, and are also connected in parallel with the capacitor C1. The connection point of the diode D3 and the IGBT module M7 connected in series serves as the positive electrode of the quasi-full-bridge sub-module, and the connection point of the diode D4 and the IGBT module M8 connected in series serves as the negative electrode of the quasi-full-bridge sub-module. The quasi-full-bridge sub-modules are connected in series, can be unidirectionally controlled to be turned on and off, and have unidirectional current-carrying capacity and bidirectional blocking voltage capacity.

[0117] In some embodiments, the thyristor is configured with a corresponding trigger circuit and a buffer circuit; the IGBT is configured with a corresponding drive circuit and a buffer circuit; the IGCT or the reverse resistance type IGCT is configured with a corresponding drive circuit and a buffer circuit; the buffer circuit is at least composed of a capacitor, or a resistor and a capacitor in series. The submodule is configured with a protection circuit, which includes but is not limited to a parallel forward thyristor or / and a reverse thyristor or / and a bypass switch.

[0118] In some embodiments, the first half-controlled valve and / or the first fully-controlled valve, and / or the second half-controlled valve, and / or the third half-controlled valve and / or the second fully-controlled valve, and / or the third fully-controlled valve are connected in parallel with a lightning arrester; wherein the lightning arresters are connected in parallel according to devices, modules or valves.

[0119] In some embodiments, the first half-controlled valve and / or the first fully-controlled valve and / or the second half-controlled valve and / or the third half-controlled valve and / or the second fully-controlled valve and / or the third fully-controlled valve further include a reactor.

[0120] An embodiment of the present invention provides an active commutation converter, comprising: at least one phase unit.

[0121] In some embodiments, when the active commutation converter includes at least one phase unit, the main branch anode bus of at least one phase unit serves as the positive input terminal, the common end of the upper bridge arm circuit of the at least one phase unit and the lower bridge arm circuit of the at least one phase unit serves as the phase output terminal, and the main branch cathode bus of the at least one phase unit serves as the negative input terminal.

[0122] Reference Figure 4 The active commutation converter can be a three-phase six-bridge-arm bridge circuit, including three phase units, and the main branches of the three phase units include three upper bridge arm circuits 1 of phase A, phase B, and phase C, and three lower bridge arm circuits 2 of phase A, phase B, and phase C. The upper bridge arm circuit 1 of phase A includes a first half-controlled valve and / or a first full-controlled valve V41 and a second half-controlled valve V42, and the first half-controlled valve and / or the first full-controlled valve V41 and the second half-controlled valve V42 are connected in series, one end of the first half-controlled valve and / or the first full-controlled valve V41 is connected to the main branch anode bus P1, and one end of the second half-controlled valve V42 is connected to one end of the second half-controlled valve V12 of the lower bridge arm circuit 2 of phase A; the upper bridge arm circuit 1 of phase B includes a first half-controlled valve and / or a first full-controlled valve V61 and a second half-controlled valve V62, and the first half-controlled valve and / or the first full-controlled valve V61 and the second half-controlled valve V62 are connected in series, One end of the first half-controlled valve and / or the first fully-controlled valve V61 is connected to the main branch anode bus P1, and one end of the second half-controlled valve V62 is connected to one end of the second half-controlled valve V32 of the B-phase lower bridge arm circuit 2; the C-phase upper bridge arm circuit 1 includes the first half-controlled valve and / or the first fully-controlled valve V21 and the second half-controlled valve V22, the first half-controlled valve and / or the first fully-controlled valve V21 and the second half-controlled valve V22 are connected in series, one end of the first half-controlled valve and / or the first fully-controlled valve V21 is connected to the main branch anode bus P1, and one end of the second half-controlled valve V22 is connected to one end of the second half-controlled valve V52 of the C-phase lower bridge arm circuit 2.

[0123] The A-phase lower bridge arm circuit 2 includes a first half-controlled valve and / or a first fully-controlled valve V11 and a second half-controlled valve V12, the first half-controlled valve and / or the first fully-controlled valve V11 and the second half-controlled valve V12 are connected in series, and one end of the first half-controlled valve and / or the first fully-controlled valve V11 is connected to the main branch cathode bus N1; the B-phase lower bridge arm circuit 2 includes a first half-controlled valve and / or a first fully-controlled valve V31 and a second half-controlled valve V32, the first half-controlled valve and / or the first fully-controlled valve V31 and the second half-controlled valve V32 are connected in series, and one end of the first half-controlled valve and / or the first fully-controlled valve V31 is connected to the main branch cathode bus N1; the C-phase lower bridge arm circuit 2 includes a first half-controlled valve and / or a first fully-controlled valve V51 and a second half-controlled valve V52, the first half-controlled valve and / or the first fully-controlled valve V51 and the second half-controlled valve V52 are connected in series, and one end of the first half-controlled valve and / or the first fully-controlled valve V51 is connected to the main branch cathode bus N1.

[0124] The three phase unit auxiliary branches include three upper bridge transfer circuits 3 for phases A, B and C, three lower bridge transfer circuits 4 for phases A, B and C, and three main shutoff circuits 5 for phases A, B and C. The upper bridge transfer circuit 3 for phase A includes a third half-controlled valve or a second fully-controlled valve V43, one end of the third half-controlled valve or the second fully-controlled valve V43 is connected to the common end of the first half-controlled valve and / or the first fully-controlled valve V41 and the second half-controlled valve V42, and the other end of the third half-controlled valve or the second fully-controlled valve V43 is connected to one end of the third fully-controlled valve V410 of the phase A main shutoff circuit 5; the upper bridge transfer circuit 3 for phase B includes a third half-controlled valve or a second fully-controlled valve V63, one end of the third half-controlled valve or the second fully-controlled valve V63 is connected to the common end of the first half-controlled valve and / or the first fully-controlled valve V61 and the second half-controlled valve V62. 1 is connected to the common end of the second half-controlled valve V62, and the other end of the third half-controlled valve or the second fully-controlled valve V63 is connected to one end of the third fully-controlled valve V630 of the B-phase main shut-off circuit 5; the C-phase upper bridge transfer circuit 3 includes a third half-controlled valve or a second fully-controlled valve V23, one end of the third half-controlled valve or the second fully-controlled valve V23 is connected to the common end of the first half-controlled valve and / or the first fully-controlled valve V21 and the second half-controlled valve V22, and the other end of the third half-controlled valve or the second fully-controlled valve V23 is connected to one end of the third fully-controlled valve V250 of the C-phase main shut-off circuit 5; The A-phase lower bridge transfer circuit 4 includes a third half-controlled valve or a second fully-controlled valve V13, one end of the third half-controlled valve or the second fully-controlled valve V13 is connected to the common end of the first half-controlled valve and / or the first fully-controlled valve V11 and the second half-controlled valve V12, and the other end of the third half-controlled valve or the second fully-controlled valve V13 is connected to one end of the third fully-controlled valve V410 of the A-phase main shut-off circuit 5; the B-phase lower bridge transfer circuit 4 includes a third half-controlled valve or the second fully-controlled valve V33, one end of the third half-controlled valve or the second fully-controlled valve V33 is connected to the first half-controlled valve and / or the first fully-controlled valve V3 1 is connected to the common end of the first half-controlled valve and / or the first fully-controlled valve V51 and the second half-controlled valve V52, and the other end of the third half-controlled valve or the second fully-controlled valve V33 is connected to one end of the third fully-controlled valve V630 of the B-phase main shutdown circuit 5; the C-phase lower bridge transfer circuit 4 includes a third half-controlled valve or a second fully-controlled valve V53, one end of the third half-controlled valve or the second fully-controlled valve V53 is connected to the common end of the first half-controlled valve and / or the first fully-controlled valve V51 and the second half-controlled valve V52, and the other end of the third half-controlled valve or the second fully-controlled valve V53 is connected to one end of the third fully-controlled valve V250 of the C-phase main shutdown circuit 5. The other end of the third fully-controlled valve V410 of the A-phase main shutdown circuit 5 is connected to the common end of the second half-controlled valve V42 of the A-phase upper bridge arm circuit 1 and the second half-controlled valve V12 of the A-phase lower bridge arm circuit 2 and serves as the A-phase output end; the other end of the third fully-controlled valve V630 of the B-phase main shutdown circuit 5 is connected to the common end of the second half-controlled valve V62 of the B-phase upper bridge arm circuit 1 and the second half-controlled valve V32 of the B-phase lower bridge arm circuit 2 and serves as the B-phase output end; the other end of the third fully-controlled valve V250 of the C-phase main shutdown circuit 5 is connected to the common end of the second half-controlled valve V22 of the C-phase upper bridge arm circuit 1 and the second half-controlled valve V52 of the C-phase lower bridge arm circuit 2 and serves as the C-phase output end.

[0125] In some embodiments, the upper bridge arm circuit and the lower bridge arm circuit of the main branch of the phase unit can also respectively adopt the first fully controlled valve, the first half-controlled valve and the second half-controlled valve; the first fully controlled valve, the first half-controlled valve and the second half-controlled valve are connected in series.

[0126] An embodiment of the present invention provides an active commutation converter, comprising: at least one phase unit and an auxiliary shutdown circuit.

[0127] In some embodiments, the actively commutated converter includes a first auxiliary shutdown circuit, and a circuit constructed by the first auxiliary shutdown circuit is connected in parallel with an upper arm circuit or a lower arm circuit of at least one main branch and a circuit constructed by a main shutdown circuit of at least one auxiliary branch.

[0128] In some embodiments, one end of the first auxiliary shutdown circuit is connected to the anode bus of the main branch of the active commutation converter, and the other end of the first auxiliary shutdown circuit is connected to the cathode bus of the main branch of the active commutation converter; the first auxiliary shutdown circuit includes a fourth full-control valve and a fifth half-control valve, and the fourth full-control valve and the fifth half-control valve are connected in series.

[0129] In some embodiments, the upper bridge arm circuit in at least one phase unit can share the fourth fully-controlled valve and the fifth half-controlled valve of the upper bridge arm of the first auxiliary shutdown circuit, and the lower bridge arm circuit in at least one phase unit can share the fourth fully-controlled valve and the fifth half-controlled valve of the lower bridge arm of the first auxiliary shutdown circuit.

[0130] In some embodiments, the first auxiliary shutoff circuit further includes a seventh half-controlled valve or a first uncontrolled valve, and the seventh half-controlled valve or the first uncontrolled valve and the fourth fully-controlled valve are connected in series.

[0131] Reference Figure 5 The first auxiliary shutdown circuit 6 includes: an auxiliary shutdown circuit of the upper bridge arm circuit 1 and an auxiliary shutdown circuit of the lower bridge arm circuit 2. The auxiliary shutdown circuit of the upper bridge arm circuit 1 includes the fourth fully controlled valve V71, the fifth half-controlled valve V81, the seventh half-controlled valve or the first uncontrolled valve V44 of the A phase, the seventh half-controlled valve or the first uncontrolled valve V64 of the B phase and the seventh half-controlled valve or the first uncontrolled valve V24 of the C phase; the auxiliary shutdown circuit of the lower bridge arm circuit 2 includes the fourth fully controlled valve V72, the fifth half-controlled valve V82, the seventh half-controlled valve or the first uncontrolled valve V14 of the A phase, the seventh half-controlled valve or the first uncontrolled valve V34 of the B phase and the seventh half-controlled valve or the first uncontrolled valve V54 of the C phase. The upper bridge arms of the A phase, the B phase and the C phase share the fourth fully controlled valve V71 and the fifth half-controlled valve V81, and the lower bridge arms of the A phase, the B phase and the C phase share the fourth fully controlled valve V72 and the fifth half-controlled valve V82.

[0132] In some embodiments, the actively commutated converter may further include a second auxiliary shutdown circuit; the second auxiliary shutdown circuit is connected in parallel with the at least one phase unit.

[0133] In some embodiments, one end of the second auxiliary shutdown circuit is connected to the main branch anode bus P1, and the other end of the second auxiliary shutdown circuit is connected to the main branch cathode bus N1; the second auxiliary shutdown circuit 7 includes a fifth full-control valve and a sixth half-control valve, and the fifth full-control valve and the sixth half-control valve are connected in series.

[0134] In some embodiments, the upper bridge arm circuit and the lower bridge arm circuit in at least one phase unit may share the fifth fully-controlled valve and the sixth half-controlled valve of the second auxiliary shutoff circuit.

[0135] Reference Figure 6 One end of the second auxiliary shutdown circuit 7 is connected to the main branch anode bus P1, and the other end of the second auxiliary shutdown circuit 7 is connected to the main branch cathode bus N1. The second auxiliary shutdown circuit 7 includes a fifth full-control valve V73 and a sixth half-control valve V83, and the fifth full-control valve V73 and the sixth half-control valve V83 are connected in series.

[0136] In some embodiments, the fifth half-controlled valve and the sixth half-controlled valve include a one-way half-controlled switch, the fourth fully-controlled valve and the fifth fully-controlled valve include at least one of a one-way fully-controlled switch, a two-way fully-controlled switch, and a sub-module series switch, and the first uncontrolled valve includes an uncontrolled switch; the uncontrolled switch is composed of a series of semiconductor devices that are uncontrolled to be turned on and off, and the semiconductor devices that are uncontrolled to be turned on and off include but are not limited to diodes.

[0137] An embodiment of the present invention provides an active commutation converter, comprising: a main shut-off circuit of at least one main branch and at least one auxiliary branch, wherein one end of the main shut-off circuit of at least one auxiliary branch serves as a phase output end, the other end of the main shut-off circuit of at least one auxiliary branch is connected to a common point where an upper bridge arm circuit and a lower bridge arm circuit of at least one main branch are connected in series, and the upper bridge arm circuit and the lower bridge arm circuit of at least one main branch respectively include a first full-control valve.

[0138] Reference Figure 7The active commutation converter can be a three-phase six-arm bridge circuit, including three main branches and three main shutdown circuits. The three main branches include three upper arm circuits 1 of phase A, phase B, and phase C and three lower arm circuits 2 of phase A, phase B, and phase C. The A-phase upper bridge arm circuit 1 includes a first full-controlled valve V41, one end of which is connected to the main branch anode bus P1, and the other end of the first full-controlled valve V41 is connected to one end of the first full-controlled valve V11 of the A-phase lower bridge arm circuit 2; the B-phase upper bridge arm circuit 1 includes a first full-controlled valve V61, one end of which is connected to the main branch anode bus P1, and the other end of the first full-controlled valve V61 is connected to one end of the first full-controlled valve V31 of the B-phase lower bridge arm circuit 2; the C-phase upper bridge arm circuit 1 includes a first full-controlled valve V21, one end of which is connected to the main branch anode bus P1, and the other end of the first full-controlled valve V21 is connected to one end of the first full-controlled valve V51 of the C-phase lower bridge arm circuit 2. The A-phase lower bridge arm circuit 2 includes a first full-control valve V11, and the other end of the first full-control valve V11 is connected to the main branch cathode bus N1; the B-phase lower bridge arm circuit 2 includes a first full-control valve V31, and the other end of the first full-control valve V31 is connected to the main branch cathode bus N1; the C-phase lower bridge arm circuit 2 includes a first full-control valve V51, and the other end of the first full-control valve V51 is connected to the main branch cathode bus N1.

[0139] The three main shutoff circuits include three main shutoff circuits 5 of phase A, phase B and phase C. The A-phase main shutdown circuit 5 includes a third full-controlled valve V410, one end of which is connected to the common end of the first full-controlled valve V41 of the A-phase upper bridge arm circuit 1 and the first full-controlled valve V11 of the A-phase lower bridge arm circuit 2, and the other end of the third full-controlled valve V410 is the A-phase output end; the B-phase main shutdown circuit 5 includes a third full-controlled valve V630, one end of which is connected to the common end of the first full-controlled valve V61 of the A-phase upper bridge arm circuit 1 and the first full-controlled valve V31 of the A-phase lower bridge arm circuit 2, and the other end of the third full-controlled valve V630 is the B-phase output end; the C-phase main shutdown circuit 5 includes a third full-controlled valve V250, one end of which is connected to the common end of the first full-controlled valve V21 of the C-phase upper bridge arm circuit 1 and the first full-controlled valve V51 of the A-phase lower bridge arm circuit 2, and the other end of the third full-controlled valve V250 is the C-phase output end.

[0140] In some embodiments, the upper bridge arm circuit and the lower bridge arm circuit of at least one main branch further include a second half-controlled valve, respectively.

[0141] Reference Figure 8 ,by Figure 7Based on, the active commutation converter can be a three-phase six-bridge arm bridge circuit, including three main branches and a main shutdown circuit. The three main branches include three upper bridge arm circuits 1 of phase A, phase B, and phase C, and three lower bridge arm circuits 2 of phase A, phase B, and phase C. The upper bridge arm circuit 1 of phase A includes a first fully-controlled valve V41 and a second half-controlled valve V42. The first fully-controlled valve V41 and the second half-controlled valve V42 are connected in series. One end of the first fully-controlled valve V41 is connected to the main branch anode bus P1, and one end of the second half-controlled valve V42 is connected to one end of the second half-controlled valve V12 of the lower bridge arm circuit 2 of phase A; the upper bridge arm circuit 1 of phase B includes a first fully-controlled valve V61 and a second half-controlled valve V62. The first fully-controlled valve V61 and the second half-controlled valve V62 are connected in series. One end of valve V61 is connected to the main branch anode bus P1, and one end of the second half-controlled valve V62 is connected to one end of the second half-controlled valve V32 of the B-phase lower bridge arm circuit 2; the C-phase upper bridge arm circuit 1 includes a first full-controlled valve V21 and a second half-controlled valve V22, the first full-controlled valve V21 and the second half-controlled valve V22 are connected in series, one end of the first full-controlled valve V21 is connected to the main branch anode bus P1, and one end of the second half-controlled valve V22 is connected to one end of the second half-controlled valve V52 of the C-phase lower bridge arm circuit 2.

[0142] The A-phase lower bridge arm circuit 2 includes a first fully-controlled valve V11 and a second half-controlled valve V12, the first fully-controlled valve V11 and the second half-controlled valve V12 are connected in series, and one end of the first fully-controlled valve V11 is connected to the main branch cathode bus N1; the B-phase lower bridge arm circuit 2 includes a first fully-controlled valve V31 and a second half-controlled valve V32, the first fully-controlled valve V31 and the second half-controlled valve V32 are connected in series, and one end of the first fully-controlled valve V31 is connected to the main branch cathode bus N1; the C-phase lower bridge arm circuit 2 includes a first fully-controlled valve V51 and a second half-controlled valve V52, the first fully-controlled valve V51 and the second half-controlled valve V52 are connected in series, and one end of the first fully-controlled valve V51 is connected to the main branch cathode bus N1.

[0143] The A-phase main shutdown circuit 5 includes a third fully-controlled valve V410, one end of which is connected to the common end of the second half-controlled valve V42 of the A-phase upper bridge arm circuit 1 and the second half-controlled valve V12 of the A-phase lower bridge arm circuit 2, and the other end of the third fully-controlled valve V410 is the A-phase output end; the B-phase main shutdown circuit 5 includes a third fully-controlled valve V630, one end of which is connected to the common end of the second half-controlled valve V62 of the A-phase upper bridge arm circuit 1 and the second half-controlled valve V32 of the A-phase lower bridge arm circuit 2, and the other end of the third fully-controlled valve V630 is the B-phase output end; the C-phase main shutdown circuit 5 includes a third fully-controlled valve V250, one end of which is connected to the common end of the second half-controlled valve V22 of the C-phase upper bridge arm circuit 1 and the second half-controlled valve V52 of the A-phase lower bridge arm circuit 2, and the other end of the third fully-controlled valve V250 is the C-phase output end.

[0144] An embodiment of the present invention provides an active commutation converter, comprising: at least one of the above-mentioned main branches, a main shutdown circuit of at least one of the above-mentioned auxiliary branches, and an auxiliary shutdown circuit; wherein, one end of the main shutdown circuit of at least one auxiliary branch serves as a phase output end, and the other end of the main shutdown circuit of at least one auxiliary branch is connected to a common point where an upper bridge arm circuit and a lower bridge arm circuit of at least one main branch are connected in series.

[0145] In some embodiments, the actively commutated converter includes a first auxiliary shutdown circuit, and a circuit constructed by the first auxiliary shutdown circuit is connected in parallel with an upper arm circuit or a lower arm circuit of at least one main branch and a circuit constructed by a main shutdown circuit of at least one auxiliary branch.

[0146] In some embodiments, one end of the first auxiliary shutdown circuit is connected to the anode bus of the main branch, and the other end of the first auxiliary shutdown circuit is connected to the cathode bus of the main branch; the first auxiliary shutdown circuit includes a fourth full-control valve and a fifth half-control valve; the fourth full-control valve and the fifth half-control valve are connected in series.

[0147] In some embodiments, the upper bridge arm circuit in at least one main branch can share the fourth fully-controlled valve and the fifth half-controlled valve of the upper bridge arm of the first auxiliary shutdown circuit, and the lower bridge arm circuit in at least one main branch can share the fourth fully-controlled valve and the fifth half-controlled valve of the lower bridge arm of the first auxiliary shutdown circuit.

[0148] In some embodiments, the first auxiliary shutoff circuit further includes a seventh half-controlled valve or a first uncontrolled valve, and the seventh half-controlled valve or the first uncontrolled valve and the fourth fully-controlled valve are connected in series.

[0149] Reference Fig. 9 ,by Figure 7 Based on the first auxiliary shutdown circuit 6, the auxiliary shutdown circuit of the upper bridge arm circuit 1 and the auxiliary shutdown circuit of the lower bridge arm circuit 2 are included. The auxiliary shutdown circuit of the upper bridge arm circuit 1 includes the fourth fully controlled valve V71, the fifth half-controlled valve V81, the seventh half-controlled valve or the first uncontrolled valve V44 of the A phase, the seventh half-controlled valve or the first uncontrolled valve V64 of the B phase and the seventh half-controlled valve or the first uncontrolled valve V24 of the C phase; the auxiliary shutdown circuit of the lower bridge arm circuit 2 includes the fourth fully controlled valve V72, the fifth half-controlled valve V82, the seventh half-controlled valve or the first uncontrolled valve V14 of the A phase, the seventh half-controlled valve or the first uncontrolled valve V34 of the B phase and the seventh half-controlled valve or the first uncontrolled valve V54 of the C phase. The upper bridge arms of the A phase, the B phase and the C phase share the fourth fully controlled valve V71 and the fifth half-controlled valve V81, and the lower bridge arms of the A phase, the B phase and the C phase share the fourth fully controlled valve V72 and the fifth half-controlled valve V82.

[0150] In some embodiments, the actively commutated converter may further include a second auxiliary shutdown circuit; the second auxiliary shutdown circuit is connected in parallel with the at least one main branch.

[0151] In some embodiments, one end of the second auxiliary shutdown circuit is connected to the main branch anode bus, and the other end of the second auxiliary shutdown circuit is connected to the main branch cathode bus; the second auxiliary shutdown circuit includes a fifth full-control valve and a sixth half-control valve, and the fifth full-control valve and the sixth half-control valve are connected in series. In some embodiments, the upper bridge arm circuit and the lower bridge arm circuit in at least one phase unit can share the fifth full-control valve and the sixth half-control valve of the second auxiliary shutdown circuit.

[0152] Reference Fig.10 ,by Figure 8 Based on it, one end of the second auxiliary shutdown circuit 7 is connected to the main branch anode bus P1, and the other end of the second auxiliary shutdown circuit 7 is connected to the main branch cathode bus N1. The second auxiliary shutdown circuit 7 includes a fifth full-control valve V73 and a sixth half-control valve V83, and the fifth full-control valve V73 and the sixth half-control valve V83 are connected in series.

[0153] In some embodiments, the auxiliary shutdown circuit is connected to the main branch anode bus and the main branch cathode bus of the active commutation converter through an isolating switch and / or a knife switch.

[0154] In some embodiments, the fifth half-controlled valve and / or the sixth half-controlled valve are connected in parallel with a lightning arrester, the fourth full-controlled valve and / or the fifth full-controlled valve are connected in parallel with a lightning arrester, and the first uncontrolled valve is connected in parallel with a lightning arrester. The above-mentioned lightning arresters are connected in parallel according to devices, modules or valves.

[0155] Optionally, the fifth half-controlled valve and / or the sixth half-controlled valve further includes a reactor.

[0156] In some embodiments, reference Fig.11 , Fig.12 , Fig.13 , Fig.14 , Fig.15 , Fig.16 , Fig.17 , Fig.18 as well as Fig.19 , shows the valve structures corresponding to each first half-controlled valve and / or the first fully-controlled valve, each second half-controlled valve, each third half-controlled valve or the second fully-controlled valve, each third fully-controlled valve, each fifth half-controlled valve, each fourth fully-controlled valve, each sixth half-controlled valve, each fifth fully-controlled valve and each seventh half-controlled valve or the first uncontrolled valve.

[0157] Reference Fig.11 The upper bridge arm circuit 1 and the lower bridge arm circuit 2 of the main branch of the phase unit respectively use the first half-controlled valve and the second half-controlled valve, the upper bridge transfer circuit 3 and the lower bridge transfer circuit 4 of the auxiliary branch respectively use the third half-controlled valve, and the main shutdown circuit 5 uses the third full-controlled valve. The first half-controlled valve, the second half-controlled valve and the third half-controlled valve respectively use Figure 3B The one-way half-controlled switch shown is composed of thyristors connected in series; the third full-controlled valve adopts Figure 3L The submodule series switch shown is composed of full-bridge submodules in series. During normal commutation, the third full-control valve is turned off to provide additional commutation voltage, forcing the current to be turned off, and reducing the reactive power loss of the active commutation converter.

[0158] Reference Fig.12 The upper bridge arm circuit 1 and the lower bridge arm circuit 2 of the main branch of the phase unit respectively use the first half-controlled valve and the second half-controlled valve, the upper bridge transfer circuit 3 and the lower bridge transfer circuit 4 of the auxiliary branch respectively use the second full-controlled valve, and the main shutdown circuit 5 uses the third full-controlled valve. The first half-controlled valve and the second half-controlled valve are respectively Figure 3B The one-way half-controlled switch shown is composed of thyristors connected in series; the second full-controlled valve adopts Figure 3F The one-way full-control switch shown is composed of reverse resistance type IGCT in series; the third full-control valve adopts Figure 3L The submodule series switch shown is composed of full-bridge submodules in series. During normal commutation, the third full-control valve is turned off to provide additional commutation voltage, forcing the current to be turned off, and reducing the reactive power loss of the active commutation converter; during a fault, if the third full-control valve cannot provide sufficient commutation voltage, the second full-control valve is turned off to provide additional higher commutation voltage.

[0159] Reference Fig.13 The upper bridge arm circuit 1 and the lower bridge arm circuit 2 of the main branch of the phase unit respectively use the first full-control valve and the second half-control valve, the upper bridge transfer circuit 3 and the lower bridge transfer circuit 4 of the auxiliary branch respectively use the third half-control valve, and the main shutdown circuit 5 uses the third full-control valve. The second half-control valve and the third half-control valve are respectively Figure 3B The one-way half-controlled switch shown is composed of thyristors connected in series; the first full-controlled valve adopts Figure 3F The one-way full-control switch shown is composed of reverse resistance type IGCT in series; the third full-control valve adopts Figure 3L The submodule series switch shown is composed of full-bridge submodules in series. During normal commutation, the third full-control valve is turned off to provide additional commutation voltage, forcing the current to be turned off, and reducing the reactive power loss of the active commutation converter; during a fault, if the third full-control valve cannot provide sufficient commutation voltage, the first full-control valve is turned off to provide additional higher commutation voltage.

[0160] Reference Fig.14 The upper bridge arm circuit 1 and the lower bridge arm circuit 2 of the main branch of the phase unit respectively use the first half-controlled valve and the second half-controlled valve, the upper bridge transfer circuit 3 and the lower bridge transfer circuit 4 of the auxiliary branch respectively use the third half-controlled valve, and the main shutdown circuit 5 uses the third full-controlled valve. The first half-controlled valve, the second half-controlled valve and the third half-controlled valve respectively use Figure 3B The one-way half-controlled switch shown is composed of thyristors connected in series; the third full-controlled valve adopts Figure 3LThe submodule series switch shown is composed of full-bridge submodules in series. The converter also includes a first auxiliary shutdown circuit 6, which uses a fourth fully controlled valve, a fifth half-controlled valve and a first uncontrolled valve. The fourth fully controlled valve uses Figure 3E The one-way full-control switch shown is composed of IGBT modules connected in series; the fifth half-control valve adopts Figure 3B The one-way half-controlled switch shown is composed of thyristors connected in series; the first uncontrolled valve adopts Figure 3A The uncontrolled switch shown is composed of diodes connected in series. During normal commutation, the third fully controlled valve is turned off to provide additional commutation voltage, forcing the current to be turned off, and reducing the reactive power loss of the active commutation converter; during a fault, if the third fully controlled valve cannot provide sufficient commutation voltage, the fourth fully controlled valve is turned off to provide additional higher commutation voltage.

[0161] Reference Fig.15 The upper bridge arm circuit 1 and the lower bridge arm circuit 2 of the main branch of the phase unit respectively use the first half-controlled valve and the second half-controlled valve, the upper bridge transfer circuit 3 and the lower bridge transfer circuit 4 of the auxiliary branch respectively use the third half-controlled valve, and the main shutdown circuit 5 uses the third full-controlled valve. The first half-controlled valve and the second half-controlled valve are respectively Figure 3C The bidirectional half-controlled switch shown is composed of anti-parallel thyristors connected in series; the third half-controlled valve adopts Figure 3B The one-way half-controlled switch shown is composed of thyristors connected in series; the third full-controlled valve adopts Figure 3L The submodule series switch shown is composed of full-bridge submodules connected in series. The converter also includes a second auxiliary shutdown circuit 7, which uses a fifth full-control valve and a sixth half-control valve. The fifth full-control valve uses Figure 3E The one-way full-control switch shown is composed of IGBT modules connected in series; the sixth half-control valve adopts Figure 3B The unidirectional half-controlled switch shown is composed of thyristors connected in series. During normal commutation, the third fully-controlled valve is turned off to provide additional commutation voltage, forcing the current to be turned off, and reducing the reactive power loss of the active commutation converter; during a fault, if the third fully-controlled valve cannot provide sufficient commutation voltage, the fifth fully-controlled valve is turned off to provide additional higher commutation voltage.

[0162] Reference Fig.16 The upper bridge arm circuit 1 and the lower bridge arm circuit 2 of the main branch adopt the first full-control valve respectively, and the main shut-off circuit 5 of the auxiliary branch adopts the third full-control valve. Figure 3F The one-way full-control switch shown is composed of reverse resistance type IGCT in series; the third full-control valve adopts Figure 3LThe submodule series switch shown is composed of full-bridge submodules in series. During normal commutation, the third full-control valve is turned off to provide additional commutation voltage, forcing the current to be turned off, and reducing the reactive power loss of the active commutation converter. During a fault, if the third full-control valve cannot provide sufficient commutation voltage, the first full-control valve is turned off to provide additional higher commutation voltage.

[0163] Reference Fig.17 The upper bridge arm circuit 1 and the lower bridge arm circuit 2 of the main branch adopt the first full-control valve and the second half-control valve respectively, and the main shut-off circuit 5 of the auxiliary branch adopts the third full-control valve. Figure 3F The one-way full-control switch shown is composed of a series connection of reverse-resistance IGCTs; the second half-control valve adopts Figure 3B The one-way half-controlled switch shown is composed of thyristors connected in series; the third full-controlled valve adopts Figure 3L The submodule series switch shown is composed of full-bridge submodules in series. During normal commutation, the third full-control valve is turned off to provide additional commutation voltage, forcing the current to be turned off, and reducing the reactive power loss of the active commutation converter. During a fault, if the third full-control valve cannot provide sufficient commutation voltage, the first full-control valve is turned off to provide additional higher commutation voltage.

[0164] Reference Fig.18 The upper bridge arm circuit 1 and the lower bridge arm circuit 2 of the main branch adopt the first half-controlled valve respectively, and the main shut-off circuit 5 of the auxiliary branch adopts the third full-controlled valve. Figure 3B The one-way half-controlled switch shown is composed of thyristors connected in series; the third full-controlled valve adopts Figure 3L The submodule series switch shown is composed of full-bridge submodules in series. The converter also includes a first auxiliary shutdown circuit 6, and the second auxiliary shutdown circuit 6 uses a fourth full-control valve, a fifth half-control valve and a first uncontrolled valve. The fourth full-control valve uses Figure 3E The one-way full-control switch shown is composed of IGBT modules connected in series; the fifth half-control valve adopts Figure 3B The one-way half-controlled switch shown is composed of thyristors connected in series; the first uncontrolled valve adopts Figure 3A The uncontrolled switch shown is composed of diodes connected in series. During normal commutation, the third fully controlled valve is turned off to provide additional commutation voltage, forcing the current to be turned off, and reducing the reactive power loss of the active commutation converter; during a fault, if the third fully controlled valve cannot provide sufficient commutation voltage, the fourth fully controlled valve is turned off to provide additional higher commutation voltage.

[0165] Reference Fig.19 The upper bridge arm circuit 1 and the lower bridge arm circuit 2 of the main branch adopt the first full-control valve and the second half-control valve respectively, and the main shut-off circuit 5 of the auxiliary branch adopts the third full-control valve. Figure 3EThe one-way full-control switch shown is composed of IGBT modules connected in series; the second half-control valve adopts Figure 3C The bidirectional half-controlled switch shown is composed of anti-parallel thyristors connected in series; the third fully controlled valve adopts Figure 3L The submodule series switch shown is composed of full-bridge submodules connected in series. The converter also includes a second auxiliary shutdown circuit 7, which uses a fifth full-control valve and a sixth half-control valve. The fifth full-control valve uses Figure 3E The one-way full-control switch shown is composed of IGBT modules connected in series; the sixth half-control valve adopts Figure 3B The unidirectional half-controlled switch shown is composed of thyristors connected in series. During normal commutation, the third fully-controlled valve is turned off to provide additional commutation voltage, forcing the current to be turned off, and reducing the reactive power loss of the active commutation converter; during a fault, if the third fully-controlled valve cannot provide sufficient commutation voltage, the fifth fully-controlled valve is turned off to provide additional higher commutation voltage. It should be noted that the positions of the first fully-controlled valve and the second half-controlled valve in this embodiment can be interchanged.

[0166] In some embodiments, Fig.11 , Fig.12 , Fig.13 , Fig.14 , Fig.15 , Fig.16 , Fig.17 , Fig.18 as well as Fig.19 Each first half-controlled valve and / or first fully-controlled valve, each second half-controlled valve, each third half-controlled valve or second fully-controlled valve, each third fully-controlled valve, each fifth half-controlled valve, each fourth fully-controlled valve, each sixth half-controlled valve, each fifth fully-controlled valve and each seventh half-controlled valve or first uncontrolled valve is connected in parallel with a lightning arrester.

[0167] The present invention provides an active commutation converter control method, which is performed by an electronic device, wherein the electronic device can be a control device, a server, or a terminal device. The control device is an independent physical controller. The server can be an independent physical server, or a server cluster or distributed system composed of multiple physical servers, or a cloud server providing cloud computing services. The terminal device can be a smart phone, a tablet computer, a laptop computer, a desktop computer, etc., but is not limited thereto. The control device, the server, and the terminal device can be directly or indirectly connected via wired or wireless communication, and the embodiments of the present invention do not impose specific restrictions.

[0168] Reference Fig. 20 , an active commutation converter control method includes: step S101 and step S102, wherein,

[0169] S101. When operating parameter information of an active commutation converter is obtained, generate inverter state control information based on the parameter information, and control the main branch to operate in an inverter state based on the inverter state control information.

[0170] In some embodiments, the electronic device monitors the operating status of the active commutation converter in real time, and obtains operating parameter information of the operating status of the active commutation converter, such as AC voltage, DC current, etc. When the electronic device obtains the operating status of the active commutation converter, the electronic device generates inverter state control information, such as a trigger pulse, and the active commutation converter operates in the inverter state according to the six-pulse inverter working mode based on the inverter state control information; for example, in a certain time period within the AC voltage cycle, the electronic device controls the first half-controlled valve and / or the first fully-controlled valve V41 and the second half-controlled valve V42 of the upper bridge arm circuit of phase A, and the first half-controlled valve and / or the first fully-controlled valve V31 and the second half-controlled valve V32 of the lower bridge arm circuit of phase B to be turned on and operate in the inverter state.

[0171] S102, when the active commutation converter includes at least one phase unit and / or an auxiliary shut-off circuit, and when a shut-off angle reference value is obtained that is less than a minimum shut-off angle setting value or commutation fault information, a first circuit conduction instruction and a first negative pressure control information are generated, and based on the first circuit conduction instruction, a transfer circuit in an auxiliary branch corresponding to the commutation bridge arm is controlled to be turned on, and based on the first negative pressure control information, a main shut-off circuit of the auxiliary branch corresponding to the commutation bridge arm is controlled to present a negative pressure; when the second half-controlled valve of the commutation bridge arm of the main branch resumes shutting down, a first circuit shut-off instruction is generated to control the main shut-off circuit of the auxiliary branch to shut down; or,

[0172] When the active commutation converter includes a main turn-off circuit of a main branch and an auxiliary branch, and when a turn-off angle reference value is obtained that is less than a minimum turn-off angle setting value or commutation fault information is obtained, a first circuit turn-off instruction is generated to control the main turn-off circuit of the auxiliary branch to turn off.

[0173] In some embodiments, the commutation fault information includes fault information that causes the natural commutation failure of the commutation bridge arm of the main branch. The commutation fault information includes an AC system fault or a DC system fault connected to the active commutation converter. The AC system fault can be judged based on an increase in the zero-sequence component of the AC voltage, a sudden change in the AC voltage, a drop in the AC voltage amplitude, an increase in the AC voltage harmonics, and an increase in the DC current. The DC system fault can be judged based on a drop in the DC voltage and an increase in the DC current, but is not limited thereto.

[0174] In some embodiments, the above-mentioned natural commutation failure is a commutation failure that occurs when the commutation is performed only by relying on the commutation voltage provided by the AC system. Whether the natural commutation failure occurs can be determined according to the closing time of the first half-controlled valve and the second half-controlled valve of the commutation bridge arm, the grid-side or valve-side AC current and AC voltage. If the first half-controlled valve and the second half-controlled valve of the commutation bridge arm have not been closed when they begin to bear positive pressure under normal AC voltage, it is determined as a natural commutation failure, but it is not limited to this.

[0175] The phase-changing bridge arm is an upper bridge arm circuit or a lower bridge arm circuit; the electronic device obtains a turn-off angle reference value, and compares the turn-off angle reference value with a preset minimum turn-off angle constant. When the turn-off angle reference value is less than the minimum turn-off angle constant, during the phase-changing period, the electronic device generates a first circuit conduction instruction and a first negative pressure control information. Subsequently, the electronic device controls the third half-controlled valve and / or the second full-controlled valve of the transfer circuit in the auxiliary branch corresponding to the phase-changing bridge arm to be turned on based on the circuit conduction instruction, and at the same time controls the third full-controlled valve of the main turn-off circuit of the auxiliary branch corresponding to the phase-changing bridge arm to present a negative pressure based on the first negative pressure control information, so that the current of the second half-controlled valve of the phase-changing bridge arm is turned on. The transfer circuit and the main shutdown circuit are moved to the auxiliary branch. Taking the A-phase upper bridge arm circuit as an example, when the A-phase upper bridge arm circuit switches to the B-phase upper bridge arm circuit, at this time, if the shutdown angle reference value is less than the minimum shutdown angle setting, such as 3 degrees, or the first half-controlled valve and / or the first full-controlled valve V41 and the second half-controlled valve V42 of the A-phase upper bridge arm circuit of the main branch will fail to switch naturally, the electronic device controls the third half-controlled valve and / or the second full-controlled valve V43 of the A-phase upper bridge transfer circuit of the auxiliary branch to be turned on based on the first circuit conduction instruction, and controls the third full-controlled valve V410 of the main shutdown circuit to present negative pressure based on the first negative pressure control information, such as controlling Figure 3L The IGBT modules M4 and M5 are turned on to make the full-bridge sub-module present a negative pressure of the capacitor C1, so that the current of the second half-controlled valve V42 of the A-phase upper bridge arm circuit is transferred to the A-phase upper bridge transfer circuit and the main shutdown circuit of the auxiliary branch; taking the A-phase lower bridge arm circuit as an example, when the A-phase lower bridge arm circuit switches to the B-phase lower bridge arm circuit, at this time, when the shutdown angle reference value is less than the minimum shutdown angle setting, such as 3 degrees, or the first half-controlled valve and / or the first fully-controlled valve V11 and the second half-controlled valve V12 of the A-phase lower bridge arm circuit of the main branch will fail to switch naturally, the electronic device controls the third half-controlled valve and / or the second fully-controlled valve V13 of the A-phase lower bridge transfer circuit of the auxiliary circuit to be turned on based on the first circuit conduction instruction, and controls the third fully-controlled valve V410 of the main shutdown circuit to present a negative pressure based on the first negative pressure control information, such as controlling Figure 3L The conduction of the middle IGBT modules M3 and M6 causes the full-bridge submodule to present a negative pressure of the capacitor C1, so that the current of the second half-controlled valve V12 of the A-phase lower bridge arm circuit is transferred to the A-phase lower bridge transfer circuit and the main shutdown circuit of the auxiliary branch.

[0176] When the second half-controlled valve of the commutation bridge arm of the main branch is restored to be closed, the electronic device generates a first circuit shutdown instruction to control the main shutdown circuit of the auxiliary branch to be closed. Taking the A-phase upper bridge arm circuit as an example, when the second half-controlled valve V42 of the A-phase upper bridge arm circuit is restored to be closed, the electronic device controls the third full-controlled valve V410 of the main shutdown circuit to be closed based on the first circuit shutdown instruction, and the third full-controlled valve V410 presents a positive capacitor pressure, thereby providing an additional commutation voltage, so that the current is commutated from the A-phase upper bridge arm circuit to the B-phase upper bridge arm circuit; taking the A-phase lower bridge arm circuit as an example, when the second half-controlled valve V12 of the A-phase lower bridge arm circuit is restored to be closed, the electronic device controls the third full-controlled valve V410 of the main shutdown circuit to be closed based on the first circuit shutdown instruction, and the third full-controlled valve V410 presents a positive capacitor pressure, thereby providing an additional commutation voltage, so that the current is commutated from the A-phase lower bridge arm circuit to the B-phase lower bridge arm circuit.

[0177] In some embodiments, before controlling the main shutdown circuit of the auxiliary branch to be shut down, second negative voltage control information is generated, and based on the second negative voltage control information, the main shutdown circuit of the auxiliary branch corresponding to the bridge arm to be switched is controlled to present a negative voltage.

[0178] In some embodiments, when the active commutation converter operates normally, the shutdown angle reference value is set to be less than the minimum shutdown angle setting; when the shutdown angle reference value is obtained to be less than the minimum shutdown angle setting and the first half-controlled valve of the commutation bridge arm of the main branch is restored to shutdown, a first circuit shutdown instruction is generated to control the third full-controlled valve corresponding to the commutation bridge arm to shut down.

[0179] In some embodiments, when the capacitor voltage of the full-bridge submodule, quasi-full-bridge submodule or clamping twin submodule of the third full-controlled valve of the main shut-off circuit is lower than the rated value and exceeds the first threshold, and the second half-controlled valve of the phase-changing bridge arm of the main branch resumes shutdown, a first circuit shutdown instruction is generated in advance; or / and the number of full-bridge submodules, quasi-full-bridge submodules or clamping twin submodules of the third full-controlled valve of the main shut-off circuit is increased; or / and the first circuit conduction instruction and the first negative pressure control information are generated in advance; the first threshold value range is 0.01 to 0.6 times the rated capacitor voltage.

[0180] In some embodiments, when the sub-module capacitor voltage of the third fully-controlled valve of the main shutdown circuit is greater than or equal to the rated value and exceeds the second threshold, and the second half-controlled valve of the switching bridge arm of the main branch resumes shutdown, the generation of the first circuit shutdown instruction is delayed; or / and the number of sub-modules of the third fully-controlled valve of the main shutdown circuit is reduced; or / and the generation of the first circuit conduction instruction and the first negative pressure control information is delayed; the second threshold value range is 0.01 to 0.6 times the rated capacitor voltage.

[0181] In some embodiments, controlling the main shut-off circuit to present a negative pressure is achieved by controlling a switch device in a submodule of the third full-control valve to be turned on so that the submodule presents a capacitive negative pressure in the direction of current flow.

[0182] In some embodiments, the second half-controlled valve of the commutation bridge arm of the main branch is restored and turned off according to the reverse recovery time of the second half-controlled valve, and the reverse recovery time is greater than or equal to the reverse recovery time of the thyristor included in the second half-controlled valve.

[0183] In some embodiments, when the third fully-controlled valve is over-pressured or fails, the second half-controlled valve or the fourth half-controlled valve of the same phase unit of the third fully-controlled valve is controlled to be conductive.

[0184] In some embodiments, when the upper bridge arm circuit and the lower bridge arm circuit respectively include a first fully-controlled valve, the control method also includes: generating a second circuit shutdown instruction when commutation fault information is obtained and the main shutdown circuit cannot provide sufficient commutation voltage, and controlling the shutdown of the first fully-controlled valve based on the second circuit shutdown instruction.

[0185] In some embodiments, when the upper bridge transfer circuit and the lower bridge transfer circuit respectively include a second fully-controlled valve, the control method also includes: generating a third circuit shutdown instruction when commutation fault information is obtained and the main shutdown circuit cannot provide sufficient commutation voltage, and controlling the second fully-controlled valve to shut down based on the third circuit shutdown instruction.

[0186] In some embodiments, when the active commutation converter also includes an auxiliary shutdown circuit, the control method also includes: generating a second circuit conduction instruction when commutation fault information is obtained and the main shutdown circuit cannot provide sufficient commutation voltage, and controlling the auxiliary shutdown circuit corresponding to the commutation bridge arm to be turned on based on the second circuit conduction instruction; generating a second circuit shutdown instruction when the first half-controlled valve and / or the second half-controlled valve of the commutation bridge arm of the main branch resumes shutdown, and controlling the auxiliary shutdown circuit to be turned off.

[0187] In some embodiments, the actively commutated converter adopts a grid control method without relying on a phase-locked loop, and voltage and frequency control can be achieved through differential power flow, including droop control, and / or virtual synchronous generator control, and / or virtual oscillator control.

[0188] In some embodiments, when the active commutation converter also includes an auxiliary shutdown circuit, the auxiliary shutdown circuit and the main branch anode bus and the main branch cathode bus of the active commutation converter are connected through an isolating switch and / or a knife switch, and in the event of a fault in the auxiliary shutdown circuit, the isolating switch and / or the knife switch are disconnected.

[0189] In some embodiments, the third full-control valve only needs to provide a smaller shut-off voltage to meet the commutation requirements during normal operation. The first full-control valve, the second full-control valve, the fourth full-control valve and the fifth full-control valve only work at the moment of fault, and need to provide a short-term overcurrent capacity and a larger shut-off voltage to shut off the fault current and provide the commutation voltage. When the first full-control valve, the second full-control valve, the fourth full-control valve and the fifth full-control valve are shut off, the current will be transferred to the parallel lightning arrester, which will provide the shut-off voltage and absorb energy. Compared with the prior art, the present invention has the function of continuously providing a certain commutation voltage and reducing reactive power loss. If the circuit is also configured with the first full-control valve, the second full-control valve, the fourth full-control valve and the fifth full-control valve, it has the function of providing sufficient commutation voltage in the event of a fault, thereby suppressing the occurrence of commutation failure.

[0190] In some embodiments, reference Fig.11 , when the turn-off angle reference value is less than the minimum turn-off angle setting value, taking the A-phase upper bridge arm circuit of the main branch as an example, when the A-phase upper bridge arm circuit switches to the B-phase upper bridge arm circuit, at this time, due to the small setting of the turn-off angle reference value, the first half-controlled valve V41 and the second half-controlled valve V42 of the A-phase upper bridge arm circuit of the main branch will fail to switch naturally. During the switching period, the third half-controlled valve V43 of the A-phase upper bridge transfer circuit of the auxiliary branch is turned on, and the third full-controlled valve V410 of the A-phase main shutdown circuit is controlled to present a negative pressure. After the current is transferred from the second half-controlled valve V42 to the auxiliary branch, after the second half-controlled valve V42 of the upper bridge arm circuit of the phase A of the main branch is restored to be closed, the first half-controlled valve V61 of the upper bridge arm circuit of the phase B and the third half-controlled valve V63 of the upper bridge transfer circuit are controlled to be turned on, the third full-controlled valve V630 of the main shut-off circuit of the phase B is controlled to present a negative pressure relative to the upper bridge arm circuit, and the third full-controlled valve V410 of the main shut-off circuit of the phase A is controlled to be shut off and present a positive pressure, so that the current of the upper bridge arm circuit of the phase A is transferred to the upper bridge arm circuit of the phase B. Then, the second half-controlled valve V62 of the upper bridge arm circuit of the phase B is controlled to be turned on, and the third full-controlled valve V630 of the main shut-off circuit of the phase B is controlled to be shut off.

[0191] In some embodiments, reference Fig.12 Taking the A-phase upper bridge arm circuit of the main branch as an example, when the A-phase upper bridge arm circuit switches phase to the B-phase upper bridge arm circuit, a fault may cause the first half-controlled valve V41 of the A-phase upper bridge arm circuit of the main branch to fail in switching phase. When the third full-controlled valve V410 of the A-phase main shut-off circuit is controlled to be shut down, the second full-controlled valve V43 is controlled to be shut down, so that the current of the A-phase upper bridge arm circuit is transferred to the B-phase upper bridge arm circuit.

[0192] In some embodiments, reference Fig.13Taking the A-phase upper bridge arm circuit of the main branch as an example, when the A-phase upper bridge arm circuit switches phase to the B-phase upper bridge arm circuit, a fault may cause the first half-controlled valve V41 of the A-phase upper bridge arm circuit of the main branch to fail in switching phase. When the third full-controlled valve V410 of the A-phase main shut-off circuit is controlled to be shut down, the first full-controlled valve V41 is controlled to be shut down, so that the current of the A-phase upper bridge arm circuit is transferred to the B-phase upper bridge arm circuit.

[0193] In some embodiments, reference Fig.14 Taking the A-phase upper bridge arm circuit of the main branch as an example, when the A-phase upper bridge arm circuit switches phase to the B-phase upper bridge arm circuit, at this time, a fault may cause the first half-controlled valve V41 of the A-phase upper bridge arm circuit of the main branch to fail to switch phase. When the third full-controlled valve V410 of the A-phase main shutdown circuit is controlled to be shut down, the fourth full-controlled valve V71 and the fifth half-controlled valve V81 are controlled to be turned on, and the current is transferred from the first half-controlled valve V41 to the auxiliary shutdown circuit, and the fourth full-controlled valve V71 is controlled to be shut down, so that the current of the A-phase upper bridge arm circuit is transferred to the B-phase upper bridge arm circuit.

[0194] In some embodiments, reference Fig.15 Taking the A-phase upper bridge arm circuit of the main branch as an example, when the A-phase upper bridge arm circuit switches to the B-phase upper bridge arm circuit, at this time, a fault may cause the first half-controlled valve V41 of the A-phase upper bridge arm circuit of the main branch to fail to switch. When the third full-controlled valve V410 of the A-phase main shutdown circuit is controlled to be shut down, the fifth full-controlled valve V73 and the sixth half-controlled valve V83 are controlled to be turned on, and the first half-controlled valve V11 and the second half-controlled valve V12 of the lower bridge arm circuit of the main branch are controlled to be reversely turned on, and the current is transferred from the first half-controlled valve V41 to the auxiliary shutdown circuit, and the fifth full-controlled valve V73 is controlled to be shut down, so that the current of the A-phase upper bridge arm circuit is transferred to the B-phase upper bridge arm circuit.

[0195] In some embodiments, reference Fig.16 , when the cut-off angle reference value is less than the minimum cut-off angle setting value, taking the A-phase upper bridge arm circuit of the main branch as an example, when the A-phase upper bridge arm circuit switches to the B-phase upper bridge arm circuit, at this time, due to the small setting of the cut-off angle reference value, the first full-control valve V41 of the A-phase upper bridge arm circuit of the main branch will cause the natural commutation failure. During the commutation period, the first full-control valve V61 of the B-phase upper bridge arm circuit is controlled to be turned on, and the third full-control valve V630 of the main cut-off circuit of the B-phase is controlled to present a negative pressure relative to the upper bridge arm circuit, and the third full-control valve V410 of the A-phase main cut-off circuit is controlled to be turned off and present a positive pressure, so that the current of the A-phase upper bridge arm circuit is transferred to the B-phase upper bridge arm circuit. If a fault occurs, the first full-control valve V41 is controlled to be turned off, so that the current of the A-phase upper bridge arm circuit is transferred to the B-phase upper bridge arm circuit.

[0196] In some embodiments, reference Fig.17, when the turn-off angle reference value is less than the minimum turn-off angle setting, taking the main branch A phase upper bridge arm circuit as an example, when the A phase upper bridge arm circuit switches to the B phase upper bridge arm circuit, at this time, due to the small setting of the turn-off angle reference value, the second half-controlled valve V42 of the A phase upper bridge arm circuit of the main branch will fail to switch naturally. During the switching period, the first full-controlled valve V61 and the second half-controlled valve V62 of the B phase upper bridge arm circuit are controlled to be turned on, and the third full-controlled valve V630 of the B phase main shutdown circuit is controlled to present a negative pressure relative to the upper bridge arm circuit, and the third full-controlled valve V410 of the A phase main shutdown circuit is turned off and presents a positive pressure, so that the current of the A phase upper bridge arm circuit is transferred to the B phase upper bridge arm circuit. If a fault occurs, it may cause the second half-controlled valve V42 of the A-phase upper bridge arm circuit of the main branch to fail in switching. When the third full-controlled valve V410 that controls the A-phase main shutdown circuit is shut down, the first full-controlled valve V41 is controlled to shut down, so that the current of the A-phase upper bridge arm circuit is transferred to the B-phase upper bridge arm circuit.

[0197] In some embodiments, reference Fig.18 Taking the A-phase upper bridge arm circuit of the main branch as an example, when the A-phase upper bridge arm circuit switches phase to the B-phase upper bridge arm circuit, at this time, a fault may cause the first half-controlled valve V41 of the A-phase upper bridge arm circuit of the main branch to fail to switch phase. When the third full-controlled valve V410 of the A-phase main shutdown circuit is controlled to be shut down, the fourth full-controlled valve V71 and the fifth half-controlled valve V81 are controlled to be turned on, and the current is transferred from the first half-controlled valve V41 to the auxiliary shutdown circuit, and the fourth full-controlled valve V71 is controlled to be shut down, so that the current of the A-phase upper bridge arm circuit is transferred to the B-phase upper bridge arm circuit.

[0198] In some embodiments, reference Fig.19 Taking the A-phase upper bridge arm circuit of the main branch as an example, when the A-phase upper bridge arm circuit switches to the B-phase upper bridge arm circuit, at this time, a fault may cause the second half-controlled valve V42 of the A-phase upper bridge arm circuit of the main branch to fail to switch. When the third full-controlled valve V410 of the A-phase main shutdown circuit is controlled to be shut down, the fifth full-controlled valve V73 and the sixth half-controlled valve V83 are controlled to be turned on, the first half-controlled valve V11 of the main branch lower bridge arm circuit and the second half-controlled valve V12 of the auxiliary branch lower bridge transfer circuit are controlled to be turned on, the first full-controlled valve V41 of the upper bridge arm circuit is controlled to be shut down, and the current is transferred from the second half-controlled valve V42 to the auxiliary shutdown circuit. When the second half-controlled valve resumes shutdown, the fifth full-controlled valve V73 is controlled to be shut down, so that the current of the A-phase upper bridge arm circuit is transferred to the B-phase upper bridge arm circuit.

[0199] In some embodiments, reference Fig.21, control the inverter operation of the main branch. When the shutdown angle reference value is less than the minimum shutdown angle setting value, control the inverter operation of the main branch. During the commutation period, control the main shutdown circuit to be turned on and present a negative pressure to transfer current. After the current transfer is completed, the second half-controlled valve of the bridge arm to be switched is restored to shutdown, and the main shutdown circuit is controlled to be turned off to provide auxiliary commutation voltage, thereby reducing reactive power loss; in case of a fault, when it is judged that the shutdown of the main shutdown circuit cannot provide sufficient commutation voltage, resulting in the possible commutation failure of the commutation bridge arm, in the case where the active commutation converter includes an auxiliary shutdown circuit, control the auxiliary shutdown circuit of the commutation bridge arm to be turned on to transfer current, and after the first half-controlled valve and / or the second half-controlled valve of the bridge arm to be switched are restored to shutdown, the auxiliary shutdown circuit is controlled to be turned off to complete the commutation process between the bridge arms.

[0200] Reference Fig. 22 The active commutation converter control device 20 may specifically include: a first control module 201 and a second control module 202, wherein:

[0201] The first control module 201 is used to generate inverter state control information based on the parameter information when the operating parameter information of the active commutation converter is obtained, and control the main branch of the bridge arm circuit to operate in the inverter state based on the inverter state control information;

[0202] The second control module 202 is used to generate a first circuit conduction instruction and a first negative pressure control information when the active commutation converter includes at least one phase unit and / or an auxiliary shut-off circuit and obtains a shut-off angle reference value that is less than a minimum shut-off angle setting value or commutation fault information, and control the transfer circuit in the auxiliary branch corresponding to the commutation bridge arm to be turned on based on the first circuit conduction instruction, and control the main shut-off circuit of the auxiliary branch corresponding to the commutation bridge arm to present a negative pressure based on the first negative pressure control information; generate a first circuit shut-off instruction when the second half-controlled valve of the commutation bridge arm of the main branch resumes shutting down, and control the main shut-off circuit of the auxiliary branch to shut down; or,

[0203] When the active commutation converter includes a main turn-off circuit of a main branch and an auxiliary branch, and when a turn-off angle reference value is obtained that is less than a minimum turn-off angle setting value or commutation fault information is obtained, a first circuit turn-off instruction is generated to control the main turn-off circuit of the auxiliary branch to turn off.

[0204] In some embodiments, the first control module 201 may include a logic circuit, or may be implemented by a central processing unit, a microprocessor, a digital signal processor, or a field programmable gate array included in the device;

[0205] The second control module 202 may include a logic circuit, or may be implemented by a central processing unit, a microprocessor, a digital signal processor, or a field programmable gate array included in the device.

[0206] An embodiment of the present invention provides a high voltage direct current transmission system, including an active commutation converter.

[0207] In some embodiments, the high voltage direct current transmission system is a two-terminal direct current transmission system or a multi-terminal direct current transmission system, and the two-terminal direct current transmission system or the multi-terminal direct current transmission system respectively includes a monopolar direct current transmission system, a bipolar direct current transmission system or a back-to-back direct current system.

[0208] Part or all of the converters that need to be operated in inversion in a two-terminal DC power transmission system or a multi-terminal DC power transmission system adopt the above-mentioned active commutation converter.

[0209] Reference Fig.23 , shows the structure of a single pole of a bipolar DC power transmission system, wherein a single pole includes a first AC system 12, a first grid commutation converter 8, a second grid commutation converter 9, a first converter transformer 10, a second converter transformer 11, a DC line 13, a second AC system 18, a first active commutation converter 14, a second active commutation converter 15, a third converter transformer 16 and a fourth converter transformer 17. When the power is forwarded, the AC power of the first AC system 12 passes through the first converter transformer 10 and the second converter transformer 11, and is rectified into DC power by the first grid commutation converter 8 and the second grid commutation converter 9, and is transmitted to the first active commutation converter 14 and the second active commutation converter 15 through the DC line 13, and is inverted into AC power, and is transmitted to the second AC system 18 after passing through the third converter transformer 16 and the fourth converter transformer 17, thereby realizing the transmission of DC power. The first active commutation converter 14 and the second active commutation converter 15 have the ability to suppress commutation failure, thereby ensuring the reliability of direct current power transmission.

[0210] The above are only some embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A phase unit, characterized in that: include: The main branch includes an upper bridge arm circuit and a lower bridge arm circuit; wherein the upper bridge arm circuit and the lower bridge arm circuit are connected in series, one end of the upper bridge arm circuit is connected to the anode bus of the main branch, and one end of the lower bridge arm circuit is connected to the cathode bus of the main branch; An auxiliary branch includes an upper bridge transfer circuit, a lower bridge transfer circuit and a main shutdown circuit; wherein one end of the upper bridge transfer circuit is connected to the upper bridge arm circuit, the other end of the upper bridge transfer circuit is connected to one end of the lower bridge transfer circuit and one end of the main shutdown circuit, the other end of the lower bridge transfer circuit is connected to the lower bridge arm circuit, and the other end of the main shutdown circuit is connected to a common point where the upper bridge arm circuit and the lower bridge arm circuit are connected in series.

2. The phase unit according to claim 1, characterized in that The upper bridge arm circuit and the lower bridge arm circuit respectively include a first half-controlled valve and / or a first fully-controlled valve; or, the upper bridge arm circuit and the lower bridge arm circuit respectively include a first half-controlled valve and / or a first fully-controlled valve and a second half-controlled valve; The upper bridge transfer circuit and the lower bridge transfer circuit respectively include a third half-controlled valve and / or a second fully-controlled valve; the main shut-off circuit includes a third fully-controlled valve.

3. The phase unit according to claim 2, characterized in that: In the case where the upper bridge arm circuit and the lower bridge arm circuit respectively include a second half-controlled valve, One end of the first half-controlled valve and / or the first fully-controlled valve of the upper bridge arm circuit is connected to the main branch anode bus, the other end of the first half-controlled valve and / or the first fully-controlled valve of the upper bridge arm circuit is connected to one end of the second half-controlled valve and one end of the third half-controlled valve and / or the second fully-controlled valve of the upper bridge transfer circuit, the other end of the second half-controlled valve of the upper bridge arm circuit is connected to one end of the third fully-controlled valve of the main shut-off circuit, and the other end of the third fully-controlled valve of the main shut-off circuit is connected to the other end of the third half-controlled valve and / or the second fully-controlled valve of the upper bridge transfer circuit; One end of the first half-controlled valve and / or the first fully-controlled valve of the lower bridge arm circuit is connected to the cathode bus of the main branch, the other end of the first half-controlled valve and / or the first fully-controlled valve of the lower bridge arm circuit is connected to one end of the second half-controlled valve and one end of the third half-controlled valve and / or the second fully-controlled valve of the lower bridge transfer circuit, the other end of the second half-controlled valve of the lower bridge arm circuit is connected to one end of the third fully-controlled valve of the main shut-off circuit, and the other end of the third fully-controlled valve of the main shut-off circuit is connected to the other end of the third half-controlled valve and / or the second fully-controlled valve of the lower bridge transfer circuit.

4. The phase unit according to claim 2, characterized in that: In the case where the upper bridge arm circuit and the lower bridge arm circuit do not include a second half-controlled valve, One end of the first half-controlled valve and / or the first fully-controlled valve of the upper bridge arm circuit is connected to the main branch anode bus, the other end of the first half-controlled valve and / or the first fully-controlled valve of the upper bridge arm circuit is connected to one end of the third half-controlled valve and / or the second fully-controlled valve of the upper bridge transfer circuit and one end of the third fully-controlled valve of the main shut-off circuit, and the other end of the third half-controlled valve and / or the second fully-controlled valve of the upper bridge transfer circuit is connected to the other end of the third fully-controlled valve of the main shut-off circuit; One end of the first half-controlled valve and / or the first fully-controlled valve of the lower bridge arm circuit is connected to the cathode bus of the main branch, the other end of the first half-controlled valve and / or the first fully-controlled valve of the lower bridge arm circuit is connected to one end of the third half-controlled valve and / or the second fully-controlled valve of the lower bridge transfer circuit and one end of the third fully-controlled valve of the main shut-off circuit, and the other end of the third half-controlled valve and / or the second fully-controlled valve of the lower bridge transfer circuit is connected to the other end of the third fully-controlled valve of the main shut-off circuit.

5. The phase unit according to claim 2, characterized in that: The first half-controlled valve and / or the first fully-controlled valve and / or the second half-controlled valve and / or the third half-controlled valve and / or the second fully-controlled valve and / or the third fully-controlled valve are connected in parallel with a lightning arrester.

6. The phase unit according to claim 2, characterized in that: The first half-controlled valve, the second half-controlled valve, and the third half-controlled valve include at least one of a one-way half-controlled switch and a two-way half-controlled switch; the first full-controlled valve and the second full-controlled valve include at least one of a one-way full-controlled switch, a two-way full-controlled switch, and a sub-module series switch; the third full-controlled valve includes at least one of a two-way full-controlled switch and a sub-module series switch.

7. The phase unit according to claim 6, characterized in that: The unidirectional half-controlled switch is composed of semiconductor devices that can be controlled to be turned on but not controlled to be turned off in series, and the semiconductor devices that can be controlled to be turned on but not controlled to be turned off include but are not limited to thyristors; The bidirectional half-controlled switch is composed of semiconductor devices that can be controlled to be turned on but not controlled to be turned off, which are connected in anti-parallel and then in series. The semiconductor devices that can be controlled to be turned on but not controlled to be turned off include but are not limited to thyristors; The unidirectional fully controlled switch is composed of semiconductor devices with unidirectional shutoff capability connected in series, and the semiconductor devices with unidirectional shutoff capability include but are not limited to insulated gate bipolar transistors and integrated gate-commutated thyristors; The bidirectional fully-controlled switch is composed of semiconductor devices with bidirectional shutoff capability connected in series, and the semiconductor devices with bidirectional shutoff capability include but are not limited to anti-parallel reverse-resistance integrated gate-commutated thyristors and anti-series insulated gate bipolar transistor modules; The submodule series switch is composed of submodules connected in series, and the submodules include but are not limited to half-bridge submodules, full-bridge submodules, quasi-full-bridge submodules, and clamped twin submodules. The switching devices of the half-bridge submodules, full-bridge submodules, quasi-full-bridge submodules or clamped twin submodules include but are not limited to insulated gate bipolar transistors and integrated gate-commutated thyristors.

8. The phase unit according to any one of claims 1 to 7, characterized in that: The main shutoff circuit also includes a fourth half-controlled valve, which is connected in parallel with the third full-controlled valve; the fourth half-controlled valve includes at least one of a one-way half-controlled switch and a two-way half-controlled switch.

9. An active commutation converter, characterized in that: include: At least one phase unit according to any one of claims 1 to 8; or, At least one phase unit and auxiliary shutdown circuit according to any one of claims 1 to 8; or, A main shut-off circuit of at least one of the main branches and at least one of the auxiliary branches; wherein one end of the main shut-off circuit of at least one of the auxiliary branches serves as a phase output end, and the other end of the main shut-off circuit of at least one of the auxiliary branches is connected to a common point where an upper bridge arm circuit and a lower bridge arm circuit of at least one of the main branches are connected in series, and the upper bridge arm circuit and the lower bridge arm circuit of at least one of the main branches respectively include a first full-control valve; or, A main shut-off circuit and an auxiliary shut-off circuit of at least one of the main branches and at least one of the auxiliary branches; wherein one end of the main shut-off circuit of at least one of the auxiliary branches is used as a phase output end, and the other end of the main shut-off circuit of at least one of the auxiliary branches is connected to a common point where an upper bridge arm circuit and a lower bridge arm circuit of at least one of the main branches are connected in series; The circuit constructed by the auxiliary shutdown circuit is connected in parallel with the upper bridge arm circuit or the lower bridge arm circuit of at least one of the main branches and the circuit constructed by the main shutdown circuit of at least one of the auxiliary branches; or, the auxiliary shutdown circuit is connected in parallel with the at least one phase unit.

10. The active commutation converter according to claim 9, characterized in that: The anode busbar of the main branch is a positive input terminal, one end of the main shutdown circuit of the auxiliary branch is a phase output terminal, and the cathode busbar of the main branch serves as a negative input terminal.

11. The active commutation converter according to claim 9, characterized in that: One end of the auxiliary shutdown circuit is connected to the anode bus of the main branch of the active commutation converter, and the other end of the auxiliary shutdown circuit is connected to the cathode bus of the main branch of the active commutation converter.

12. The active commutation converter according to claim 9, characterized in that: The auxiliary shut-off circuit and the main branch anode busbar and the main branch cathode busbar of the active commutation converter are connected via an isolating switch and / or a knife switch.

13. The active commutation converter according to any one of claims 9 to 12, characterized in that: In the case where the circuit constructed by the auxiliary shutoff circuit is connected in parallel with the upper bridge arm circuit or the lower bridge arm circuit of at least one of the main branches and the circuit constructed by the main shutoff circuit of at least one of the auxiliary branches, the auxiliary shutoff circuit includes a fourth fully controlled valve; Alternatively, the auxiliary shutoff circuit comprises a fourth fully-controlled valve and a fifth half-controlled valve; the fourth fully-controlled valve and the fifth half-controlled valve are connected in series; or, In case the auxiliary shutoff circuit is connected in parallel with the at least one phase unit, the auxiliary shutoff circuit comprises a fifth fully controlled valve; Alternatively, the auxiliary shutoff circuit includes a fifth fully-controlled valve and a sixth half-controlled valve; the fifth fully-controlled valve and the sixth half-controlled valve are connected in series.

14. The active commutation converter according to claim 13, characterized in that: In the case where the circuit constructed by the auxiliary shutdown circuit is connected in parallel with the upper bridge arm circuit or the lower bridge arm circuit of at least one of the main branches and the circuit constructed by the main shutdown circuit of at least one of the auxiliary branches, the auxiliary shutdown circuit also includes a seventh half-controlled valve or a first uncontrolled valve; the seventh half-controlled valve or the first uncontrolled valve, the fourth fully-controlled valve and the fifth half-controlled valve are connected in series, and the circuit after the series connection is connected in parallel with the upper bridge arm circuit or the lower bridge arm circuit; or, the circuit after the series connection is connected in parallel with the circuit in which the upper bridge arm circuit or the lower bridge arm circuit and the main shutdown circuit of at least one of the auxiliary branches are connected in series.

15. The active commutation converter according to claim 13, characterized in that: When the auxiliary shutoff circuit is connected in parallel with the at least one phase unit, the first half-controlled valve and the second half-controlled valve include bidirectional half-controlled switches.

16. The active commutation converter according to claim 13, characterized in that: In the case where the circuit constructed by the auxiliary shutoff circuit is connected in parallel with the upper bridge arm circuit or the lower bridge arm circuit of at least one of the main branches and the circuit constructed by the main shutoff circuit of at least one of the auxiliary branches, the upper bridge arm circuit and / or the lower bridge arm circuit share the fourth full-control valve and / or the fifth half-control valve of the auxiliary shutoff circuit; In the case where the auxiliary shutoff circuit is connected in parallel with the at least one phase unit, the upper bridge arm circuit and the lower bridge arm circuit share the fifth fully-controlled valve and / or the sixth half-controlled valve of the auxiliary shutoff circuit.

17. The active commutation converter according to claim 13, characterized in that: The fifth half-controlled valve and the sixth half-controlled valve include a one-way half-controlled switch, the fourth fully-controlled valve and the fifth fully-controlled valve include at least one of a one-way fully-controlled switch, a two-way fully-controlled switch, and a sub-module series switch, and the first uncontrolled valve includes an uncontrolled switch; the uncontrolled switch is composed of a series connection of semiconductor devices for uncontrolled opening and closing, and the uncontrolled opening and closing semiconductor devices include but are not limited to diodes.

18. The active commutation converter according to claim 13, characterized in that: The fifth half-controlled valve, and / or the fourth full-controlled valve, and / or the fifth full-controlled valve, and / or the sixth half-controlled valve are connected in parallel with a lightning arrester.

19. An active commutation converter control method, characterized in that: Used to control the active commutation converter according to any one of claims 9 to 18, comprising: In the case of obtaining the operating parameter information of the active commutation converter, generating the inverter state control information based on the parameter information, and controlling the main branch of the bridge arm circuit to operate in the inverter state based on the inverter state control information; When the active commutation converter includes at least one phase unit and / or an auxiliary shut-off circuit, and when the shut-off angle reference value of the active commutation converter is less than the minimum shut-off angle setting or commutation fault information is obtained, a first circuit conduction instruction and a first negative pressure control information are generated, and the transfer circuit in the auxiliary branch corresponding to the commutation bridge arm is controlled to be turned on based on the first circuit conduction instruction, and the main shut-off circuit of the auxiliary branch corresponding to the commutation bridge arm is controlled to present a negative pressure based on the first negative pressure control information; when the second half-controlled valve of the commutation bridge arm of the main branch resumes shutdown, a first circuit shut-off instruction is generated to control the main shut-off circuit of the auxiliary branch to shut down; or, when the active commutation converter includes the main shut-off circuits of the main branch and the auxiliary branch, and when the shut-off angle reference value is less than the minimum shut-off angle setting or commutation fault information is obtained, a first circuit shut-off instruction is generated to control the main shut-off circuit of the auxiliary branch to shut down.

20. The method according to claim 19, characterized in that When the active commutation converter is operating normally, the shutdown angle reference value is set to be less than the minimum shutdown angle setting; when the shutdown angle reference value is obtained to be less than the minimum shutdown angle setting and the second half-controlled valve of the commutation bridge arm of the main branch is restored to shutdown, a first circuit shutdown instruction is generated to control the third full-controlled valve corresponding to the commutation bridge arm to shut down.

21. The method according to claim 19, characterized in that Before controlling the main shutdown circuit of the auxiliary branch to be shut down, second negative voltage control information is generated, and based on the second negative voltage control information, the main shutdown circuit of the auxiliary branch corresponding to the to-be-changed bridge arm is controlled to present a negative voltage.

22. The method according to claim 19, characterized in that When the capacitor voltage of the submodule of the third fully-controlled valve of the main shutdown circuit is lower than the rated value and exceeds the first threshold, and the second half-controlled valve of the phase-changing bridge arm of the main branch resumes shutdown, a first circuit shutdown instruction is generated in advance; or / and the number of submodules of the third fully-controlled valve of the main shutdown circuit is increased; or / and a first circuit conduction instruction and a first negative pressure control information are generated in advance; the first threshold value range is 0.01 to 0.6 times the rated capacitor voltage.

23. The method according to claim 19, characterized in that When the sub-module capacitor voltage of the third fully-controlled valve of the main shutdown circuit is greater than or equal to the rated value and exceeds the second threshold, and the second half-controlled valve of the phase-changing bridge arm of the main branch resumes shutdown, the generation of the first circuit shutdown instruction is delayed; or / and the number of sub-modules of the third fully-controlled valve of the main shutdown circuit is reduced; or / and the generation of the first circuit conduction instruction and the first negative pressure control information is delayed; the second threshold value range is 0.01 to 0.6 times the rated capacitor voltage.

24. The method according to claim 19, characterized in that Controlling the main shut-off circuit to present a negative pressure is achieved by controlling the switch device in the submodule of the third full-control valve to be turned on so that the submodule presents a capacitive negative pressure in the direction of current flow.

25. The method according to claim 19, characterized in that The second half-controlled valve of the commutation bridge arm of the main branch is restored and closed according to the reverse recovery time of the second half-controlled valve, and the reverse recovery time is greater than or equal to the reverse recovery time of the thyristor included in the second half-controlled valve.

26. The method according to claim 19, characterized in that In case of overpressure or failure of the third fully-controlled valve, the second half-controlled valve or the fourth half-controlled valve of the same phase unit of the third fully-controlled valve is controlled to be conductive.

27. The method according to claim 19, characterized in that The method further comprises: When the upper bridge arm circuit and the lower bridge arm circuit respectively include a first fully-controlled valve, and phase switching fault information is obtained, and the main shutdown circuit cannot provide sufficient phase switching voltage, a second circuit shutdown instruction is generated, and the first fully-controlled valve is controlled to be shut down based on the second circuit shutdown instruction.

28. The method according to claim 19, characterized in that In the case where the upper bridge transfer circuit and the lower bridge transfer circuit respectively include a second fully controlled valve, the method further includes: When the commutation fault information is obtained and the main shut-off circuit cannot provide sufficient commutation voltage, a third circuit shut-off instruction is generated, and the second full-control valve is controlled to be shut off based on the third circuit shut-off instruction.

29. The method according to claim 19, characterized in that In the case where the active commutation converter further includes an auxiliary shutdown circuit, the method further includes: When the commutation fault information is obtained and the main shutdown circuit cannot provide sufficient commutation voltage, a second circuit conduction instruction is generated, and the auxiliary shutdown circuit corresponding to the commutation bridge arm is controlled to be turned on based on the second circuit conduction instruction. When the first half-controlled valve and / or the second half-controlled valve of the commutation bridge arm of the main branch resumes shutdown, a fourth circuit shutdown instruction is generated to control the auxiliary shutdown circuit to be turned off.

30. The method according to claim 19, characterized in that The active commutation converter controls voltage and frequency using a network control method.

31. The method according to any one of claims 19 to 30, characterized in that: When the active commutation converter further includes an auxiliary shutdown circuit, the auxiliary shutdown circuit and the main branch anode bus and the main branch cathode bus of the active commutation converter are connected via an isolating switch and / or a knife switch, and in the event of a fault in the auxiliary shutdown circuit, the isolating switch and / or the knife switch are disconnected.

32. An active commutation converter control device, characterized in that: Used to control the active commutation converter according to any one of claims 9 to 18, comprising: A first control module, configured to, when obtaining operating parameter information of the active commutation converter, generate inverter state control information based on the parameter information, and control the main branch to operate in an inverter state based on the inverter state control information; The second control module is used to generate a first circuit conduction instruction and a first negative pressure control information when the active commutation converter includes at least one phase unit and / or an auxiliary shut-off circuit and a shut-off angle reference value is obtained that is less than a minimum shut-off angle setting or commutation fault information, and control the transfer circuit in the auxiliary branch corresponding to the commutation bridge arm to be turned on based on the first circuit conduction instruction, and control the main shut-off circuit of the auxiliary branch corresponding to the commutation bridge arm to present a negative pressure based on the first negative pressure control information; generate a first circuit shut-off instruction when the second half-controlled valve of the commutation bridge arm of the main branch resumes shutting down, and control the main shut-off circuit of the auxiliary branch to shut down; or, generate a first circuit shut-off instruction when the active commutation converter includes the main shut-off circuits of the main branch and the auxiliary branch, and a shut-off angle reference value is obtained that is less than a minimum shut-off angle setting or commutation fault information, and control the main shut-off circuit of the auxiliary branch to shut down.

33. A high voltage direct current transmission system, comprising the actively commutated converter according to any one of claims 9 to 18.

34. The system according to claim 33, characterized in that The high-voltage direct current transmission system is a two-terminal direct current transmission system or a multi-terminal direct current transmission system, and the two-terminal direct current transmission system or the multi-terminal direct current transmission system respectively includes a unipolar direct current transmission system, a bipolar direct current transmission system or a back-to-back direct current system.

35. The system according to claim 34, characterized in that Part or all of the converters that need to be inverted in the two-terminal DC power transmission system or the multi-terminal DC power transmission system adopt the active commutation converter.

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