Centralized controllable turn-off power grid commutation converter, control method, device and system

Abstract

The invention provides a centralized controllable turn-off power grid commutation converter, a control method, a control device and a control system, and relates to the technical field of high-voltage direct-current power transmission. The centralized controllable turn-off power grid commutation converter comprises a main circuit which comprises at least one phase of upper bridge arm circuit and at least one phase of lower bridge arm circuit, one end of the at least one phase of upper bridge arm circuit is connected with an anode bus of the main circuit, and the other end of the at least one phase of upper bridge arm circuit is connected with one end of the at least one phase of lower bridge arm circuit; the other end of at least one phase of lower bridge arm circuit is connected with a cathode bus of the main circuit; each of the at least one phase of upper bridge arm circuit and the at least one phase of lower bridge arm circuit comprises a first half-control valve, and each comprises a first full-control valve or shares the first full-control valve; and the auxiliary circuit comprises a turn-off circuit, one end of the turn-off circuit is connected with the anode bus of the main circuit, and the other end of the turn-off circuit is connected with the cathode bus of the main circuit. According to the invention, commutation failure can be suppressed, and the high-voltage direct-current transmission reliability 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 centralized controllable shutdown grid commutation converter, a control method and device, and a system. 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 and / or 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 the existing grid-commutated converter with fully controlled devices and adding auxiliary circuits to form a controllably shut-down 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 controllable shutdown grid-commutated converter that uses full-control device replacement to suppress commutation failure has a small device capacity and its reliability needs to be verified; the existing controllable shutdown grid-commutated converter that suppresses commutation failure by adding auxiliary circuits has a complex structure and reduced reliability; the above two 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 generally cannot be activated during steady-state operation, so it still needs to rely on the grid commutation voltage for commutation, resulting in the minimum shutdown angle cannot be controlled too small, and still requires more reactive power consumption. Summary of the invention

[0005] In order to suppress the occurrence of high-voltage direct current transmission commutation failure, reduce the cost of controllably shut-down grid commutation converters, improve the reliability of high-voltage direct current transmission, reduce the shutdown angle reference value, and reduce the reactive power consumption, the present invention provides a centralized controllably shut-down grid commutation converter, a control method and device, and a system.

[0006] The present invention provides a centralized controllable shutdown grid phase-commutation converter, which adopts the following technical solution:

[0007] A centralized controllable shutdown grid commutation converter, comprising:

[0008] A main circuit, comprising at least one-phase upper bridge arm circuit and at least one-phase lower bridge arm circuit, wherein one end of the at least one-phase upper bridge arm circuit is connected to the anode bus of the main circuit, the other end of the at least one-phase upper bridge arm circuit is connected to one end of the at least one-phase lower bridge arm circuit, and the other end of the at least one-phase lower bridge arm circuit is connected to the cathode bus of the main circuit; the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit both comprise a first half-controlled valve, and the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit both comprise a first fully-controlled valve or share a first fully-controlled valve;

[0009] The auxiliary circuit includes a shut-down circuit, one end of which is connected to the anode bus of the main circuit, and the other end of which is connected to the cathode bus of the main circuit.

[0010] According to some embodiments, the shut-off circuit includes: a second fully-controlled valve; one end of the second fully-controlled valve is connected to the anode bus of the main circuit, and the other end of the second fully-controlled valve is connected to the cathode bus of the main circuit;

[0011] The second full-control valve includes at least one of a one-way full-control switch, a two-way full-control switch, and a sub-module series switch.

[0012] According to some embodiments, the shutoff circuit further comprises a second half-controlled valve and / or a first uncontrolled valve; the second half-controlled valve and / or the first uncontrolled valve are connected in series with the second fully-controlled valve;

[0013] The second half-controlled valve includes a one-way half-controlled switch, and the first uncontrolled valve includes an uncontrolled switch.

[0014] According to some embodiments, a lightning arrester is connected in parallel to the second fully-controlled valve, and / or a lightning arrester is connected in parallel to the second half-controlled valve and / or the first uncontrolled valve.

[0015] According to some embodiments, the first half-controlled valve includes at least one of a bidirectional half-controlled switch, an anti-parallel uncontrolled switch, and a unidirectional half-controlled switch; the first fully-controlled valve includes at least one of a unidirectional fully-controlled switch, a bidirectional fully-controlled switch, and a sub-module series switch.

[0016] According to some embodiments, the bidirectional half-controlled switch is composed of semiconductor devices that can be controlled to turn on but cannot be controlled to turn off, which are connected in anti-parallel and then in series. The semiconductor devices that can be controlled to turn on but cannot be controlled to turn off include but are not limited to thyristors;

[0017] 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;

[0018] The uncontrolled switch is composed of semiconductor devices that are uncontrolled to be turned on and off in series, and the semiconductor devices that are uncontrolled to be turned on and off include but are not limited to diodes;

[0019] 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, integrated gate-commutated thyristors, and reverse-blocking integrated gate-commutated thyristors;

[0020] 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;

[0021] 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 semiconductor devices of the half-bridge submodules, full-bridge submodules, quasi-full-bridge submodules, and clamped twin submodules include but are not limited to insulated gate bipolar transistors and integrated gate-commutated thyristors.

[0022] According to some embodiments, when both the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit include a first fully-controlled valve, the first half-controlled valve and the first fully-controlled valve are connected in series.

[0023] According to some embodiments, one end of the first half-controlled valve of the at least one-phase upper bridge arm circuit is connected to the anode bus of the main circuit, and one end of the first full-controlled valve of the at least one-phase upper bridge arm circuit is connected to one end of the first full-controlled valve of the at least one-phase lower bridge arm circuit; one end of the first half-controlled valve of the at least one-phase lower bridge arm circuit is connected to the cathode bus of the main circuit; or,

[0024] One end of the first full-control valve of the at least one-phase upper bridge arm circuit is connected to the anode bus of the main circuit, and one end of the first half-control valve of the at least one-phase upper bridge arm circuit is connected to one end of the first half-control valve of the at least one-phase lower bridge arm circuit; one end of the first full-control valve of the at least one-phase lower bridge arm circuit is connected to the cathode bus of the main circuit.

[0025] According to some embodiments, the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit each further include a second uncontrolled valve, which is connected in series with the first fully-controlled valve; the second uncontrolled valve includes any one of an uncontrolled switch, an anti-parallel uncontrolled switch and a unidirectional half-controlled switch.

[0026] According to some embodiments, a lightning arrester is connected in parallel to the first half-controlled valve and / or a lightning arrester is connected in parallel to the first full-controlled valve.

[0027] According to some embodiments, a third half-control valve is connected in parallel at both ends of the first full-control valve; or,

[0028] In the case where both the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit further include a second uncontrolled valve, a third half-controlled valve is connected in parallel to both ends of the first fully-controlled valve and the second uncontrolled valve connected in series;

[0029] The third half-controlled valve includes at least one of a one-way half-controlled switch and a two-way half-controlled switch.

[0030] According to some embodiments, the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit both further include a third fully-controlled valve and / or a third uncontrolled valve. When the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit both further include a third uncontrolled valve, the third fully-controlled valve and the third uncontrolled valve are connected in series and are connected in anti-parallel to a series circuit consisting of the second uncontrolled valve and the first fully-controlled valve.

[0031] The third fully-controlled valve includes at least one of a one-way fully-controlled switch, a two-way fully-controlled switch, and a sub-module series switch; and the third uncontrolled valve includes an uncontrolled switch.

[0032] According to some embodiments, a fourth half-control valve is connected in parallel at both ends of the third full-control valve; or,

[0033] When the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit both include a third uncontrolled valve, a fourth half-controlled valve is connected in parallel at both ends of the third fully-controlled valve and the third uncontrolled valve in series; the fourth half-controlled valve includes a one-way half-controlled switch.

[0034] According to some embodiments, the first fully-controlled valve of the at least one-phase upper bridge arm circuit and the first fully-controlled valve of the at least one-phase lower bridge arm circuit are connected in parallel with an absorption circuit.

[0035] According to some embodiments, when the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit share a first full-control valve; one end of the first full-control valve is connected to the common end of the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit, and the other end of the first full-control valve is the output end.

[0036] According to some embodiments, a fifth half-controlled valve is connected in parallel at both ends of the first full-controlled valve, and the fifth half-controlled valve includes at least one of a one-way half-controlled switch and a two-way half-controlled switch.

[0037] According to some embodiments, the shutoff circuit of the auxiliary circuit and the anode busbar of the main circuit are connected via an isolating switch and / or a knife switch, and the cathode busbar of the main circuit is connected via an isolating switch and / or a knife switch.

[0038] According to some embodiments, the first fully-controlled valve and / or the first half-controlled valve further includes a reactor.

[0039] According to some embodiments, the first full-control valve and the third full-control valve are combined into one full-control valve including a two-way full-control switch; and / or,

[0040] The third half-controlled valve and the fourth half-controlled valve are combined into a half-controlled valve including a bidirectional half-controlled switch.

[0041] The present invention provides a control method for centralized controllable shutdown of a grid phase-commutation converter, which adopts the following technical solution:

[0042] A centralized controllable shutdown grid-commutated converter control method is used to control the centralized controllable shutdown grid-commutated converter, comprising:

[0043] In the case of obtaining the operating parameter information of the centralized controllable off-grid phase-commutated converter, generating the inverter state control information based on the parameter information, and controlling the main circuit to operate in the inverter state based on the inverter state control information;

[0044] When the commutation fault information is obtained, a first on instruction and a first off instruction are generated, and based on the first on instruction, another lower bridge arm circuit of the same phase of the commutation bridge arm is controlled to be reversely conducted and the off circuit of the auxiliary circuit is controlled to be conducted; based on the first off instruction, the first full-control valve of the commutation bridge arm is controlled to be turned off;

[0045] When the first half-controlled valve of the phase-changing bridge arm of the main circuit resumes shutting down, a second shut-down instruction is generated to control the shut-down circuit of the auxiliary circuit to shut down.

[0046] According to some embodiments, when the first fully-controlled valve is composed of submodules connected in series with switches, or connected in parallel with a lightning arrester, or connected in parallel with an absorption circuit, the first fully-controlled valve is closed during commutation in normal operation to provide additional commutation voltage.

[0047] According to some embodiments, the recovery and shutdown of the first half-controlled valve of the commutation bridge arm of the main circuit is determined based on the reverse recovery time of the first half-controlled valve, and the reverse recovery time is greater than or equal to the reverse recovery time of the thyristor included in the first half-controlled valve.

[0048] According to some embodiments, in the case of overpressure or failure of the second fully-controlled valve, the upper bridge arm circuit and the lower bridge arm circuit of one phase are controlled to be turned on at the same time.

[0049] According to some embodiments, a third half-controlled valve is connected in parallel at both ends of the first fully-controlled valve, or a third half-controlled valve is connected in series at both ends of the first fully-controlled valve and the second uncontrolled valve, and when the first fully-controlled valve is over-pressured or fails, the third half-controlled valve is controlled to be conductive.

[0050] According to some embodiments, when the shut-off circuit of the auxiliary circuit and the anode bus of the main circuit are connected through an isolating switch and / or a knife switch, and the cathode bus of the main circuit is connected through an isolating switch and / or a knife switch, and the shut-off circuit fails, the isolating switch and / or the knife switch are separated.

[0051] According to some embodiments, when the semiconductor device in the bidirectional half-controlled switch of the first half-controlled valve of the centralized controllable off grid-commutated converter is subjected to forward and reverse voltage exceeding the limit, the bidirectional half-controlled switch is controlled to conduct forward and reverse.

[0052] According to some embodiments, a fourth half-controlled valve is connected in parallel at both ends of the third fully-controlled valve, or a fourth half-controlled valve is connected in parallel at both ends of the third fully-controlled valve and the third uncontrolled valve in series, and when the third fully-controlled valve is over-pressured or fails, the fourth half-controlled valve is controlled to be turned on.

[0053] According to some embodiments, when at least one phase upper bridge arm circuit and at least one phase lower bridge arm circuit both further include a third fully-controlled valve and a third uncontrolled valve, and when the shutdown circuit of the control auxiliary circuit is shut down, the third fully-controlled valve is controlled to be shut down.

[0054] The present invention provides a centralized controllable shutdown grid commutation converter control device, which adopts the following technical solution:

[0055] A centralized controllable shutdown grid-commutated converter control device is used to control the centralized controllable shutdown grid-commutated converter, comprising: a first control module, a second control module and a third control module, wherein:

[0056] A first control module is used to generate inverter state control information based on the parameter information when the operation parameter information of the centralized controllable shutdown grid-commutated converter is obtained, and control the main circuit to operate in the inverter state based on the inverter state control information;

[0057] A second control module is used to generate a first on-commutation instruction and a first off-commutation instruction when the commutation fault information is obtained, and control the other lower bridge arm circuit of the same phase of the commutation bridge arm to reverse conduct based on the first on-commutation instruction and control the off circuit of the auxiliary circuit to conduct; and control the first full-control valve of the commutation bridge arm to be turned off based on the first off-commutation instruction;

[0058] The third control module is used to generate a second shutdown instruction when the first half-controlled valve of the phase-changing bridge arm of the main circuit resumes shutdown, so as to control the shutdown circuit of the auxiliary circuit to shut down.

[0059] The present invention provides a high-voltage direct current power transmission system, comprising the centralized controllable shutdown grid phase-changing converter.

[0060] 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.

[0061] According to some embodiments, 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 centralized controllable shutdown grid-commutated converter.

[0062] In summary, the present invention includes the following beneficial technical effects:

[0063] When a commutation failure may occur due to a fault in the AC system, the lower bridge arm circuit of the commutation bridge arm of the control main circuit is reversely conducted and the shutdown circuit of the auxiliary circuit is turned on to form a current in parallel with the commutation bridge arm, the first full-controlled valve of the control main circuit is turned off, and the current is transferred to the auxiliary circuit. After the first half-controlled valve of the commutation bridge arm of the main circuit is restored to be turned off, the shutdown circuit of the control auxiliary circuit is turned off; the first half-controlled valve of the main circuit adopts a bidirectional switch, and the forward and reverse semiconductor devices share a resistor-capacitor circuit and a voltage-equalizing circuit; six bridge arms share one shutdown circuit, which reduces the number of full-controlled devices and improves the utilization rate of the lightning arrester, thereby reducing costs, reducing complexity, and improving reliability; in normal operation, if the first full-controlled valve has the ability to continuously shut off current, using the first full-controlled valve to shut off current can improve the power factor and reduce reactive power loss; because the first half-controlled valve adopts a bidirectional half-controlled switch, the bidirectional thyristors protect each other through a protective triggering function, which can reduce the withstand voltage level of the bridge arm, so the number of thyristor stages connected in series with the bidirectional half-controlled switch is reduced, thereby improving the efficiency of the converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 This is one of the schematic diagrams of a centralized controllable shutdown grid commutation converter according to an embodiment of the present invention;

[0065] Figure 2This is the second schematic diagram of a centralized controllable shutdown grid commutation converter according to an embodiment of the present invention;

[0066] Figure 3 This is the third schematic diagram of a centralized controllable shutdown grid commutation converter according to an embodiment of the present invention;

[0067] Figure 4 This is the fourth schematic diagram of the centralized controllable shutdown grid commutation converter according to the embodiment of the present invention;

[0068] Figure 5 This is the fifth schematic diagram of the centralized controllable shutdown grid commutation converter according to the embodiment of the present invention;

[0069] Figure 6 This is the sixth schematic diagram of the centralized controllable shutdown grid commutation converter according to the embodiment of the present invention;

[0070] Fig. 7A , Figure 7B , Figure 7C , Fig.7D , Fig. 7E , Figure 7F , Figure 7G , Figure 7H , Fig.7I , Figure 7J , Figure 7K , Figure 7L as well as Figure 7M Schematic diagram of the valve structure of an embodiment of the present invention;

[0071] Figure 8 It is one of the circuit diagrams of a centralized controllable shut-off grid-commutated converter including a valve structure according to an embodiment of the present invention;

[0072] Fig. 9 This is the second circuit diagram of a centralized controllable shutdown grid-commutated converter including a valve structure according to an embodiment of the present invention;

[0073] Fig.10 This is the third circuit diagram of a centralized controllable shutdown grid-commutated converter including a valve structure according to an embodiment of the present invention;

[0074] Fig.11 This is the fourth circuit diagram of a centralized controllable off grid commutation converter including a valve structure according to an embodiment of the present invention;

[0075] Fig.12 This is the fifth circuit diagram of a centralized controllable shutdown grid-commutated converter including a valve structure according to an embodiment of the present invention;

[0076] Fig.13 This is the sixth circuit diagram of a centralized controllable off grid commutation converter including a valve structure according to an embodiment of the present invention;

[0077] Fig.14This is the seventh circuit diagram of a centralized controllable shutdown grid-commutated converter including a valve structure according to an embodiment of the present invention;

[0078] Fig.15 This is the eighth circuit diagram of a centralized controllable shut-off grid-commutated converter including a valve structure according to an embodiment of the present invention;

[0079] Fig.16 is a circuit diagram of a centralized controllable shutdown grid-commutated converter including a lightning arrester according to an embodiment of the present invention;

[0080] Fig.17 1 is a block diagram of a control method for centralized controllable shutdown of a grid-commutated converter according to an embodiment of the present invention;

[0081] Fig.18 It is a schematic flow chart of a control method for centralized controllable shutdown of a grid commutation converter according to an embodiment of the present invention;

[0082] Fig.19 It is a block diagram of a control device for centralized controllable shutdown of a grid-commutated converter according to an embodiment of the present invention;

[0083] Fig. 20 The present invention is an embodiment of a direct current transmission system including a centralized controllable shutdown grid-commutated converter;

[0084] Fig.21A The embodiment of the present invention provides Figure 8 Single-phase ground fault simulation test diagram of valve structure;

[0085] Fig. 21B The embodiment of the present invention provides Figure 8 Three-phase short-circuit fault simulation test diagram of valve structure;

[0086] Fig.22A The embodiment of the present invention provides Fig.12 Single-phase ground fault simulation test diagram of valve structure;

[0087] Fig. 22B The embodiment of the present invention provides Fig.12 Three-phase short-circuit fault simulation test diagram of the valve structure.

[0088] Explanation of the accompanying drawings: 1. upper bridge arm circuit; 2. lower bridge arm circuit; 3. shutdown circuit; 4. first grid-commutating converter; 5. second grid-commutating converter; 6. first converter transformer; 7. second converter transformer; 8. first AC system; 9. DC line; 10. first centralized controllable shutdown grid-commutating converter; 11. second centralized controllable shutdown grid-commutating converter; 12. third converter transformer; 13. fourth converter transformer; 14. second AC system; 201. first control module; 202. second control module; 203. third control module. DETAILED DESCRIPTION

[0089] The following is combined with Figure 1-22B The present invention is described in further detail.

[0090] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings 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.

[0091] An embodiment of the present invention provides a centralized controllable shutdown grid-commutated converter, comprising: a main circuit and an auxiliary circuit, wherein the main circuit comprises at least one-phase upper bridge arm circuit and at least one-phase lower bridge arm circuit, one end of the at least one-phase upper bridge arm circuit is connected to the anode bus of the main circuit, the other end of the at least one-phase upper bridge arm circuit is connected to one end of the at least one-phase lower bridge arm circuit, and the other end of the at least one-phase lower bridge arm circuit is connected to the cathode bus of the main circuit; the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit both comprise a first half-controlled valve, and the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit both comprise a first fully-controlled valve or share a first fully-controlled valve.

[0092] Reference Figure 1 , the main circuit can be a three-phase six-bridge arm circuit, including: three upper bridge arm circuits 1 and three lower bridge arm circuits 2, and the three upper bridge arm circuits 1 and the three lower bridge arm circuits 2 have a one-to-one correspondence, and each upper bridge arm circuit 1 and lower bridge arm circuit 2 in the corresponding relationship corresponds to one phase of electricity, one end of each upper bridge arm circuit 1 is connected to the anode bus of the main circuit, the other end of each upper bridge arm circuit 1 is connected to one end of its corresponding lower bridge arm circuit 2, and the other end of its corresponding lower bridge arm circuit 2 is connected to the cathode bus of the main circuit; each upper bridge arm circuit 1 and lower bridge arm circuit 2 include a first half-controlled valve and a first fully-controlled valve; wherein the first half-controlled valve and the first fully-controlled valve are connected in series; one end of the first half-controlled valve of each upper bridge arm circuit 1 is connected to the anode bus of the main circuit, and one end of the first fully-controlled valve of each upper bridge arm circuit 1 is connected to one end of the first fully-controlled valve of its corresponding lower bridge arm circuit 2; the other end of the first half-controlled valve of each lower bridge arm circuit 2 is connected to the cathode bus of the main circuit.

[0093] In some embodiments, reference Figure 1The A-phase upper bridge arm circuit 1 includes a first half-controlled valve V41 and a first fully-controlled valve V42, which are connected in series, one end of the first half-controlled valve V41 is connected to the main circuit anode bus P1, and one end of the first fully-controlled valve V42 is connected to the A-phase lower bridge arm circuit 2; the B-phase upper bridge arm circuit 1 includes a first half-controlled valve V61 and a first fully-controlled valve V62, which are connected in series, one end of the first half-controlled valve V61 is connected to the main circuit anode bus P1, and one end of the first fully-controlled valve V62 is connected to the B-phase lower bridge arm circuit 2; the C-phase upper bridge arm circuit 1 includes a first half-controlled valve V21 and a first controlled valve V22, which are connected in series, one end of the first half-controlled valve V21 is connected to the main circuit anode bus P1, and one end of the first fully-controlled valve V22 is connected to the C-phase lower bridge arm circuit 2.

[0094] The A-phase lower bridge arm circuit 2 includes a first half-controlled valve V11 and a first fully-controlled valve V12, which are connected in series, one end of the first half-controlled valve V11 is connected to the cathode bus N1 of the main circuit, and one end of the first fully-controlled valve V12 is connected to one end of the first fully-controlled valve V42 of the A-phase upper bridge arm circuit 1; the B-phase lower bridge arm circuit 2 includes a first half-controlled valve V31 and a first fully-controlled valve V32, which are connected in series, One end of the half-controlled valve V31 is connected to the cathode bus N1 of the main circuit, and one end of the first fully-controlled valve V32 is connected to one end of the first fully-controlled valve V62 of the B-phase upper bridge arm circuit 1; the C-phase lower bridge arm circuit 2 includes a first half-controlled valve V51 and a first fully-controlled valve V52, the first half-controlled valve V51 and the first fully-controlled valve V52 are connected in series, one end of the first half-controlled valve V51 is connected to the cathode bus N1 of the main circuit, and one end of the first fully-controlled valve V52 is connected to the first fully-controlled valve V22 of the C-phase upper bridge arm circuit 1.

[0095] In some embodiments, one end of the first fully-controlled valve of at least one phase upper bridge arm circuit is connected to the anode bus of the main circuit, and one end of the first half-controlled valve of at least one phase upper bridge arm circuit is connected to one end of the first half-controlled valve of at least one phase lower bridge arm circuit; one end of the first fully-controlled valve of at least one phase lower bridge arm circuit is connected to the cathode bus of the main circuit, that is, the circuit positions of the first fully-controlled valve and the first half-controlled valve can be interchanged.

[0096] In some embodiments, the first full-control valve of at least one phase upper bridge circuit and the first full-control valve of at least one phase lower bridge arm circuit are connected in parallel with an absorption circuit, which can absorb the energy generated when the first full-control valve is turned off, and is usually a series circuit of a capacitor and a resistor.

[0097] In some embodiments, when at least one phase upper bridge arm circuit and at least one phase lower bridge arm circuit share a first full-control valve, one end of the first full-control valve is connected to the common end of at least one phase upper bridge arm circuit and at least one phase lower bridge arm circuit, and the other end of the first full-control valve is the output end; wherein, a fifth half-controlled valve is connected in parallel at both ends of the first full-control valve, and the fifth half-controlled valve includes at least one of a unidirectional half-controlled switch and a bidirectional half-controlled switch.

[0098] The auxiliary circuit includes a shut-off circuit, one end of which is connected to the anode bus of the main circuit, and the other end of which is connected to the cathode bus of the main circuit. The shut-off circuit includes: a second full-control valve; one end of the second full-control valve is connected to the anode bus of the main circuit, and the other end of the second full-control valve is connected to the cathode bus of the main circuit.

[0099] Reference Figure 1 The auxiliary circuit includes: a shut-down circuit 3, one end of which is connected to the anode bus of the main circuit, and the other end of which is connected to the cathode bus of the main circuit; the shut-down circuit includes a second full-control valve, one end of which is connected to the anode bus of the main circuit, and the other end of which is connected to the cathode bus of the main circuit.

[0100] In some embodiments, reference Figure 1 The shut-off circuit 3 includes a second full-control valve V71 , one end of the second full-control valve V71 is connected to the anode bus P1 of the main circuit, and the other end of the second full-control valve V71 is connected to the cathode bus N1 of the main circuit.

[0101] In some embodiments, the shutdown circuit 3 of the auxiliary circuit and the anode bus of the main circuit are connected through an isolating switch and / or a knife switch, and the shutdown circuit 3 of the auxiliary circuit and the cathode bus of the main circuit are connected through an isolating switch and / or a knife switch.

[0102] In some embodiments, the first fully-controlled valve and the second fully-controlled valve respectively 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 half-controlled valve includes at least one of a two-way half-controlled switch, an anti-parallel uncontrolled switch, and a one-way half-controlled switch.

[0103] In some embodiments, the shut-off circuit also includes a second half-controlled valve and / or a first uncontrolled valve, one end of the second half-controlled valve and / or the first uncontrolled valve is connected to the anode bus of the main circuit, the other end of the second half-controlled valve and / or the first uncontrolled valve is connected to one end of the second fully-controlled valve, and the other end of the second fully-controlled valve is connected to the cathode bus of the main circuit; or, one end of the second half-controlled valve and / or the first uncontrolled valve is connected to the cathode bus of the main circuit, the other end of the second half-controlled valve and / or the first uncontrolled valve is connected to one end of the second fully-controlled valve, and the other end of the second fully-controlled valve is connected to the anode bus of the main circuit.

[0104] Reference Figure 2The shut-off circuit 3 also includes a second half-controlled valve and / or a first uncontrolled valve V72, one end of the second half-controlled valve and / or the first uncontrolled valve V72 is connected to the anode bus P1 of the main circuit, the other end of the second half-controlled valve and / or the first uncontrolled valve V72 is connected to one end of the second fully-controlled valve V71, and the other end of the second fully-controlled valve V71 is connected to the cathode bus N1 of the main circuit.

[0105] In some embodiments, the second half-controlled valve includes a one-way half-controlled switch for assisting the second fully-controlled valve in bearing positive and reverse voltages, and the first uncontrolled valve includes an uncontrolled switch for assisting the second fully-controlled valve in bearing reverse voltages.

[0106] In some embodiments, at least one phase upper bridge arm circuit and at least one phase lower bridge arm circuit each further include a second uncontrolled valve, and the second uncontrolled valve is connected in series with the first fully-controlled valve.

[0107] The three upper bridge arm circuits 1 and the three lower bridge arm circuits 2 all further include a second uncontrolled valve, and the second uncontrolled valve is connected in series with the first fully-controlled valve.

[0108] Reference Figure 3 The A-phase upper bridge arm circuit 1 includes a second uncontrolled valve V43, one end of the second uncontrolled valve V43 is connected to one end of the A-phase lower bridge arm circuit 2, and the other end of the second uncontrolled valve V43 is connected to the first fully-controlled valve V42 of the A-phase upper bridge arm circuit 1; the B-phase upper bridge arm circuit 1 includes a second uncontrolled valve V63, one end of the second uncontrolled valve V63 is connected to one end of the B-phase lower bridge arm circuit 2, and the other end of the second uncontrolled valve V63 is connected to the first fully-controlled valve V62 of the B-phase upper bridge arm circuit 1; the C-phase upper bridge arm circuit 1 includes a second uncontrolled valve V23, one end of the second uncontrolled valve V23 is connected to one end of the C-phase lower bridge arm circuit 2, and the other end of the second uncontrolled valve V23 is connected to the first fully-controlled valve V22 of the C-phase upper bridge arm circuit 1.

[0109] The A-phase lower bridge arm circuit 2 includes a second uncontrolled valve V13, one end of which is connected to the second uncontrolled valve V43 of the A-phase upper bridge arm circuit 1, and the other end of the second uncontrolled valve V13 is connected to the first fully-controlled valve V12 of the A-phase lower bridge arm circuit 2; the B-phase lower bridge arm circuit 2 includes a second uncontrolled valve V33, one end of which is connected to the second uncontrolled valve V63 of the B-phase upper bridge arm circuit 1, and the other end of the second uncontrolled valve V33 is connected to the first fully-controlled valve V32 of the B-phase lower bridge arm circuit 2; the C-phase lower bridge arm circuit 2 includes a second uncontrolled valve V53, one end of which is connected to the second uncontrolled valve V23 of the C-phase upper bridge arm circuit 1, and the other end of the second uncontrolled valve V53 is connected to the first fully-controlled valve V52 of the C-phase lower bridge arm circuit 2.

[0110] In some embodiments, the second uncontrolled valve includes any one of an uncontrolled switch, an anti-parallel uncontrolled switch, and a one-way half-controlled switch.

[0111] In some embodiments, on the basis that at least one phase upper bridge arm circuit and at least one phase lower bridge arm circuit both include a second uncontrolled valve, at least one phase upper bridge arm circuit and at least one phase lower bridge arm circuit also include a third fully-controlled valve and / or a third uncontrolled valve connected in series. When the at least one phase upper bridge arm circuit and the at least one phase lower bridge arm circuit both include a third uncontrolled valve, the third fully-controlled valve and the third uncontrolled valve are connected in series and connected in parallel with the series circuit composed of the second uncontrolled valve and the first fully-controlled valve.

[0112] On the basis that the three upper bridge arm circuits 1 and the three lower bridge arm circuits 2 also include a second uncontrolled valve, the three upper bridge arm circuits 1 and the three lower bridge arm circuits 2 also include a third fully-controlled valve and a third uncontrolled valve connected in series, the third fully-controlled valve and the third uncontrolled valve are connected in series and are anti-parallel connected to the series circuit composed of the second uncontrolled valve and the first fully-controlled valve.

[0113] Reference Figure 4 The A-phase upper bridge arm circuit 1 also includes a third fully-controlled valve V44 and a third uncontrolled valve V45, which are connected in series and anti-parallel to the circuit in which the first fully-controlled valve V42 and the second uncontrolled valve V43 are connected in series; the B-phase upper bridge arm circuit 1 also includes a third fully-controlled valve V64 and a third uncontrolled valve V65, which are connected in series and anti-parallel to the circuit in which the first fully-controlled valve V62 and the second uncontrolled valve V63 are connected in series; the C-phase upper bridge arm circuit 1 also includes a third fully-controlled valve V24 and a third uncontrolled valve V25, which are connected in series and anti-parallel to the circuit in which the first fully-controlled valve V22 and the second uncontrolled valve V23 are connected in series.

[0114] The A-phase lower bridge arm circuit 2 also includes a third fully-controlled valve V14 and a third uncontrolled valve V15, which are connected in series and anti-parallel to the circuit in which the first fully-controlled valve V12 and the second uncontrolled valve V13 are connected in series; the B-phase lower bridge arm circuit 2 also includes a third fully-controlled valve V34 and a third uncontrolled valve V35, which are connected in series and anti-parallel to the circuit in which the first fully-controlled valve V32 and the second uncontrolled valve V33 are connected in series; the C-phase lower bridge arm circuit 2 also includes a third fully-controlled valve V54 and a third uncontrolled valve V55, which are connected in series and anti-parallel to the circuit in which the first fully-controlled valve V52 and the second uncontrolled valve V53 are connected in series.

[0115] In some embodiments, the third fully-controlled valve includes at least one of a one-way fully-controlled switch, a two-way fully-controlled switch, and a sub-module series switch; and the third uncontrolled valve includes an uncontrolled switch.

[0116] In some embodiments, on the basis that at least one phase upper bridge arm circuit and at least one phase lower bridge arm circuit both include a first half-controlled valve and a first fully-controlled valve, at least one phase upper bridge arm circuit and at least one phase lower bridge arm circuit both also include a third half-controlled valve, and the third half-controlled valves are connected in parallel at both ends of the first fully-controlled valve. When at least one phase upper bridge arm circuit and at least one phase lower bridge arm circuit both include a second uncontrolled valve, the third half-controlled valve is connected in parallel to the circuit in which the first fully-controlled valve and the second uncontrolled valve are connected in series.

[0117] Reference Figure 5 The A-phase upper bridge arm circuit 1 also includes a third half-controlled valve V46, which is connected in parallel with a circuit in which the first full-controlled valve V42 and the second uncontrolled valve V43 are connected in series; the B-phase upper bridge arm circuit 1 also includes a third half-controlled valve V66, which is connected in parallel with a circuit in which the first full-controlled valve V62 and the second uncontrolled valve V63 are connected in series; the C-phase upper bridge arm circuit 1 also includes a third half-controlled valve V26, which is connected in parallel with a circuit in which the first full-controlled valve V22 and the second uncontrolled valve V23 are connected in series.

[0118] The A-phase lower bridge arm circuit 2 also includes a third half-controlled valve V16, which is connected in parallel with the circuit in which the first full-controlled valve V12 and the second uncontrolled valve V13 are connected in series; the B-phase lower bridge arm circuit 2 also includes a third half-controlled valve V36, which is connected in parallel with the circuit in which the first full-controlled valve V32 and the second uncontrolled valve V33 are connected in series; the C-phase lower bridge arm circuit 2 also includes a third half-controlled valve V56, which is connected in parallel with the circuit in which the first full-controlled valve V52 and the second uncontrolled valve V53 are connected in series. In some embodiments, when the second uncontrolled valve is not configured, the third half-controlled valve can be connected in parallel with the first full-controlled valve, for example, the third half-controlled valve V46 included in the A-phase upper bridge arm circuit 1 is connected in parallel with the first full-controlled valve V42.

[0119] In some embodiments, the third half-controlled valve includes at least one of a one-way half-controlled switch and a two-way half-controlled switch.

[0120] Reference Figure 6 On the basis that the three upper bridge arm circuits 1 and the three lower bridge arm circuits 2 all include a first half-controlled valve, a first fully-controlled valve, a second uncontrolled valve and a third half-controlled valve, the three upper bridge arm circuits 1 and the three lower bridge arm circuits 2 all include a third fully-controlled valve and a third uncontrolled valve; the third fully-controlled valve and the third uncontrolled valve are connected in series, and are anti-parallel connected to the circuit in which the first fully-controlled valve and the second uncontrolled valve are connected in series, and then anti-parallel connected with a fourth half-controlled valve.

[0121] Reference Figure 6The A-phase upper bridge arm circuit 1 also includes a third fully-controlled valve V44 and a third uncontrolled valve V45, which are connected in series and anti-parallel to the circuit in which the first fully-controlled valve V42 and the second uncontrolled valve V43 are connected in series, and a fourth half-controlled valve V47 is connected in parallel at both ends of the anti-parallel connection; the B-phase upper bridge arm circuit 1 also includes a third fully-controlled valve V64 and a third uncontrolled valve V65, which are connected in series and anti-parallel to the circuit in which the first fully-controlled valve V62 and the second uncontrolled valve V63 are connected in series, and a fourth half-controlled valve V67 is connected in parallel at both ends of the anti-parallel connection; the C-phase upper bridge arm circuit 1 also includes a third fully-controlled valve V24 and a third uncontrolled valve V25, which are connected in series and anti-parallel to the circuit in which the first fully-controlled valve V22 and the second uncontrolled valve V23 are connected in series, and a fourth half-controlled valve V27 is connected in parallel at both ends of the anti-parallel connection.

[0122] The A-phase lower bridge arm circuit 2 also includes a third fully-controlled valve V14 and a third uncontrolled valve V15, which are connected in series and anti-parallel to the circuit in which the first fully-controlled valve V12 and the second uncontrolled valve V13 are connected in series, and a fourth half-controlled valve V17 is connected in parallel at both ends of the anti-parallel connection; the B-phase lower bridge arm circuit 2 also includes a third fully-controlled valve V34 and a third uncontrolled valve V35, which are connected in series and anti-parallel to the circuit in which the first fully-controlled valve V32 and the second uncontrolled valve V33 are connected in series, and a fourth half-controlled valve V37 is connected in parallel at both ends of the anti-parallel connection; the C-phase lower bridge arm circuit 2 also includes a third fully-controlled valve V54 and a third uncontrolled valve V55, which are connected in series and anti-parallel to the circuit in which the first fully-controlled valve V52 and the second uncontrolled valve V53 are connected in series, and a fourth half-controlled valve V57 is connected in parallel at both ends of the anti-parallel connection.

[0123] In some embodiments, the fourth half-controlled valve includes a one-way half-controlled switch.

[0124] In some embodiments, when the third uncontrolled valve is not configured, the fourth half-controlled valve is connected in parallel with the third fully-controlled valve.

[0125] In some embodiments, the first fully-controlled valve and the third fully-controlled valve are combined into a fully-controlled valve including a bidirectional fully-controlled switch; and / or the third half-controlled valve and the fourth half-controlled valve are combined into a half-controlled valve including a bidirectional half-controlled switch.

[0126] In some embodiments, the first fully controlled valve and / or the first half-controlled valve in at least one phase upper bridge arm circuit and at least one phase lower bridge arm circuit further include a reactor. Optionally, the second half-controlled valve and / or the first uncontrolled valve and / or the third half-controlled valve in the shut-off circuit further include a reactor.

[0127] The continuous operating voltage peak value range of the first fully-controlled valve is 0.01 to 0.2 times the continuous operating voltage peak of the upper bridge arm circuit or the lower bridge arm circuit, the continuous operating voltage peak value range of the first half-controlled valve is 0.8 to 1.0 times the continuous operating voltage peak of the upper bridge arm circuit or the lower bridge arm circuit, and the continuous operating voltage peak value range of the second fully-controlled valve is 0.4 to 0.8 times the continuous operating voltage peak of the upper bridge arm circuit or the lower bridge arm circuit.

[0128] 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), IGBT (Insulated Gate Bipolar Transistor), reverse-blocking IGCT, 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.

[0129] In some embodiments, reference Fig. 7A , the uncontrolled switch includes at least one diode 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 7B The unidirectional half-controlled switch includes a thyristor connected in series, which can only control the opening but not 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 7C The bidirectional half-controlled switch is composed of anti-parallel thyristors connected in series. It can only control the opening but not the closing. It has bidirectional current-carrying capacity and bidirectional blocking voltage capacity. Fig.7D The anti-parallel unidirectional half-controlled switch and the uncontrolled switch are composed of anti-parallel thyristors and diodes 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. Fig. 7E The unidirectional fully controlled switch includes an IGBT module connected in series, the IGBT module includes an IGBT and a diode connected in anti-parallel therewith, which is only unidirectionally controlled to be turned on and off, and has bidirectional current flow and unidirectional blocking voltage capability; refer to Figure 7F , the unidirectional fully controlled switch includes a reverse resistance type IGCT 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 7GThe unidirectional fully controlled switch includes an IGBT module and a diode 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 7H The unidirectional fully controlled switch includes a reverse-resistance IGCT and a thyristor anti-parallel series circuit, which has a bidirectional control opening and a unidirectional control closing, and has a bidirectional current flow and a bidirectional blocking voltage capability; refer to Fig.7I 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 7J The bidirectional fully controlled switch includes a series circuit of reverse-resistance IGCTs 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 7K The sub-module series switch includes a half-bridge sub-module connected in series, the half-bridge sub-module includes two IGBT modules and a capacitor, the connection point of the two IGBT modules serves as the positive electrode of the half-bridge sub-module, and the other end of one of the IGBT modules 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 7L The sub-module series switch includes a full-bridge sub-module connected in series. The full-bridge sub-module includes four IGBT modules and a capacitor. The IGBT modules are connected in series in pairs and then in parallel, and are also connected in parallel with the capacitor. The connection points of the IGBT modules connected in series in pairs serve as the positive and negative electrodes of the full-bridge sub-module respectively. 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; refer to Figure 7M The sub-module series switch includes a quasi-full-bridge sub-module connected in series. The quasi-full-bridge sub-module includes two IGBT modules, two diodes and a capacitor. The IGBT module and the diode are connected in series and then in parallel, and are also connected in parallel with the capacitor. The connection points of the IGBT module and the diode connected in series serve as the positive and negative electrodes of the quasi-full-bridge sub-module respectively. The quasi-full-bridge sub-modules are connected in series and can be controlled to be turned on and off in one direction, and have bidirectional current-carrying capacity and bidirectional blocking voltage capacity.

[0130] 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 composed of at least a capacitor; or is composed of a resistor and a capacitor series circuit.

[0131] In some embodiments, reference Figure 8 , Fig. 9 , Fig.10 , Fig.11 , Fig.12 , Fig.13 , Fig.14 , Fig.15 as well as Fig.16 , showing the valve structures corresponding to each first fully-controlled valve, the second fully-controlled valve, each third fully-controlled valve, each first half-controlled valve, the second half-controlled valve or the first uncontrolled valve, each second uncontrolled valve, each third uncontrolled valve, each third half-controlled valve and each fourth half-controlled valve.

[0132] Reference Figure 8 In the main circuit, the A-phase upper bridge arm circuit 1 includes a first half-controlled valve V41 and a first fully-controlled valve V42 connected in series, the B-phase upper bridge arm circuit 1 includes a first half-controlled valve V61 and a first fully-controlled valve V62 connected in series, the C-phase upper bridge arm circuit 1 includes a first half-controlled valve V21 and a first fully-controlled valve V22 connected in series, the A-phase lower bridge arm circuit 2 includes a first half-controlled valve V11 and a first fully-controlled valve V12 connected in series, the B-phase lower bridge arm circuit 2 includes a first half-controlled valve V31 and a first fully-controlled valve V32 connected in series, and the C-phase lower bridge arm circuit 2 includes a first half-controlled valve V51 and a first fully-controlled valve V52 connected in series. Each first half-controlled valve adopts Figure 7C The bidirectional half-controlled switch shown in the figure is composed of anti-parallel thyristors connected in series. The anti-parallel thyristors can share a buffer circuit and a voltage balancing circuit. Each first full-control valve adopts Fig. 7E The one-way full-control switch shown in the figure is composed of IGBT modules connected in series; optionally, if each first full-control valve adopts Figure 7K , Figure 7L or Figure 7M The submodules shown are connected in series with the switches. During commutation, the first fully controlled valve is turned off to provide additional commutation voltage and force the current to be turned off, which will reduce the reactive power loss of the centralized controllable shutdown grid commutation converter.

[0133] In the auxiliary circuit, the shut-off circuit 3 includes a second fully controlled valve V71. The second fully controlled valve V71 adopts Fig. 7E The unidirectional fully-controlled switch shown is composed of IGBT modules connected in series. Since the second fully-controlled valve V71 needs to withstand the entire forward DC voltage, a larger number of series stages are required. At the same time, due to the anti-parallel diodes in the IGBT modules, the converter does not have the ability to operate with reverse DC voltage.

[0134] Reference Fig. 9 ,and Figure 8 The valve structure is different in that the first full control valve adopts Figure 7H The unidirectional fully controlled switch shown is composed of a reverse-resistance type IGCT and a thyristor connected in anti-parallel and then in series.

[0135] Reference Fig.10 ,and Figure 8 The valve structure is different from that of the first embodiment in that the shut-off circuit also includes a second half-controlled valve V72. The second half-controlled valve V72 adopts Figure 7BThe unidirectional half-controlled switch shown is composed of thyristors in series. Since the second half-controlled valve V72 and the second fully-controlled valve V71 jointly bear the forward DC voltage, the number of series-connected second fully-controlled valves V71 can be reduced. At the same time, since the thyristor of the second half-controlled valve V72 can withstand reverse DC voltage, the converter has the ability to operate with reverse DC voltage.

[0136] Reference Fig.11 ,and Figure 8 The valve structure is different in that the A, B, C three-phase upper bridge arm circuit and the A, B, C three-phase lower bridge arm circuit further include a second uncontrolled valve respectively.

[0137] In the main circuit, the A-phase upper bridge arm circuit 1 includes a first half-controlled valve V41, a first fully-controlled valve V42, and a second uncontrolled valve V43 connected in series, the B-phase upper bridge arm circuit 1 includes a first half-controlled valve V61, a first fully-controlled valve V62, and a second uncontrolled valve V63 connected in series, the C-phase upper bridge arm circuit 1 includes a first half-controlled valve V21, a first fully-controlled valve V22, and a second uncontrolled valve V23 connected in series, the A-phase lower bridge arm circuit 2 includes a first half-controlled valve V11, a first fully-controlled valve V12, and a second uncontrolled valve V13 connected in series, the B-phase lower bridge arm circuit 2 includes a first half-controlled valve V31, a first fully-controlled valve V32, and a second uncontrolled valve V33 connected in series, and the C-phase lower bridge arm circuit 2 includes a first half-controlled valve V51, a first fully-controlled valve V52, and a second uncontrolled valve V53 connected in series; the above-mentioned second uncontrolled valve adopts Fig.7D The anti-parallel unidirectional half-controlled switch and the uncontrolled switch shown are composed of anti-parallel thyristors and diodes connected in series. The anti-parallel thyristors and diodes can share a buffer circuit and a voltage-equalizing circuit.

[0138] Reference Fig.12 ,and Figure 8 The valve structures are different in that the A, B, C three-phase upper bridge arm circuit 1 and the A, B, C three-phase lower bridge arm circuit 2 further include a third fully-controlled valve and a third uncontrolled valve, respectively.

[0139] In the main circuit, the A-phase upper bridge arm circuit 1 includes a first half-controlled valve V41, a first fully-controlled valve V42, a second uncontrolled valve V43, a third fully-controlled valve V44 and a third uncontrolled valve V45, and the first fully-controlled valve V42 and the second uncontrolled valve V43 connected in series are connected in anti-parallel with the third fully-controlled valve V44 and the third uncontrolled valve V45 connected in series; the B-phase upper bridge arm circuit 1 includes a first half-controlled valve V61, a first fully-controlled valve V62, a second uncontrolled valve V63, a third fully-controlled valve V64 and a third uncontrolled valve V45. The first fully controlled valve V62 and the second uncontrolled valve V63 are connected in series with the third fully controlled valve V64 and the third uncontrolled valve V65 in anti-parallel connection; the C phase upper bridge arm circuit 1 includes the first half-controlled valve V21, the first fully controlled valve V22, the second uncontrolled valve V23, the third fully controlled valve V24 and the third uncontrolled valve V25, the first fully controlled valve V22 and the second uncontrolled valve V23 are connected in series with the third fully controlled valve V24 and the third uncontrolled valve V25 in anti-parallel connection; the A phase lower bridge arm The circuit 2 includes a first half-controlled valve V11, a first fully-controlled valve V12, a second uncontrolled valve V13, a third fully-controlled valve V14 and a third uncontrolled valve V15, wherein the first fully-controlled valve V12 and the second uncontrolled valve V13 connected in series are connected in anti-parallel with the third fully-controlled valve V14 and the third uncontrolled valve V15 connected in series; the B-phase lower bridge arm circuit 2 includes a first half-controlled valve V31, a first fully-controlled valve V32, a second uncontrolled valve V33, a third fully-controlled valve V34 and a third uncontrolled valve V35, wherein the first fully-controlled valve V12 and the second uncontrolled valve V13 connected in series are connected in anti-parallel with the third fully-controlled valve V14 and the third uncontrolled valve V15 connected in series; The controlled valve V32 and the second uncontrolled valve V33 are connected in anti-parallel with the third fully controlled valve V34 and the third uncontrolled valve V35 connected in series; the C phase lower bridge arm circuit 2 includes a first half-controlled valve V51, a first fully controlled valve V52, a second uncontrolled valve V53, a third fully controlled valve V54 and a third uncontrolled valve V55, the first fully controlled valve V52 and the second uncontrolled valve V53 in series are connected in anti-parallel with the third fully controlled valve V54 and the third uncontrolled valve V55 in series; the second uncontrolled valve and the third uncontrolled valve adopt Fig. 7A The uncontrolled switch shown is composed of diodes in series.

[0140] Reference Fig.13 ,and Figure 8 The valve structure is different in that the A, B, C three-phase upper bridge arm circuit and the A, B, C three-phase lower bridge arm circuit further include a second uncontrolled valve and a third half-controlled valve respectively.

[0141] In the main circuit, the A-phase upper bridge arm circuit 1 includes a first half-controlled valve V41, a first fully-controlled valve V42, a second uncontrolled valve V43 and a third half-controlled valve V46, and the first fully-controlled valve V42 and the second uncontrolled valve V43 are connected in series with the third half-controlled valve V46 in parallel; the B-phase upper bridge arm circuit 1 includes a first half-controlled valve V61, a first fully-controlled valve V62, a second uncontrolled valve V63 and a third half-controlled valve V66, and the first fully-controlled valve V62 and the second uncontrolled valve V63 are connected in series with the third half-controlled valve V66 in parallel; the C-phase upper bridge arm circuit 1 includes a first half-controlled valve V21, a first fully-controlled valve V22, a second uncontrolled valve V23 and a third half-controlled valve V26, and the first fully-controlled valve V22 and the second uncontrolled valve V23 are connected in series with the third half-controlled valve V26 in parallel; The lower bridge arm circuit 2 includes a first half-controlled valve V11, a first fully-controlled valve V12, a second uncontrolled valve V13 and a third half-controlled valve V16, and the first fully-controlled valve V12 and the second uncontrolled valve V13 are connected in series with the third half-controlled valve V16 in parallel; the B-phase lower bridge arm circuit 2 includes a first half-controlled valve V31, a first fully-controlled valve V32, a second uncontrolled valve V33 and a third half-controlled valve V36, and the first fully-controlled valve V32 and the second uncontrolled valve V33 are connected in series with the third half-controlled valve V36 in parallel; the C-phase lower bridge arm circuit 2 includes a first half-controlled valve V51, a first fully-controlled valve V52, a second uncontrolled valve V53 and a third half-controlled valve V56, and the first fully-controlled valve V52 and the second uncontrolled valve V53 are connected in series with the third half-controlled valve V56 in parallel; the above-mentioned second uncontrolled valve adopts Fig. 7A The uncontrolled switch shown is composed of diodes in series; the third half-controlled valve adopts Figure 7C The bidirectional half-controlled switch shown is composed of anti-parallel thyristors connected in series, and the anti-parallel thyristors can share a resistor-capacitor circuit and a voltage-equalizing circuit.

[0142] Reference Fig.14 ,and Fig.13 The valve structure is different from that of the first embodiment in that the shut-off circuit also includes a second half-controlled valve V72. The second half-controlled valve V72 adopts Figure 7B The unidirectional half-controlled switch shown is composed of thyristors connected in series.

[0143] Reference Fig.15 ,and Fig.12 The valve structure is different in that the A, B, C three-phase upper bridge arm circuit and the A, B, C three-phase lower bridge arm circuit further include a third half-controlled valve and a fourth half-controlled valve respectively.

[0144] In the main circuit, the A-phase upper bridge arm circuit 1 includes a first half-controlled valve V41, a first fully-controlled valve V42, a second uncontrolled valve V43, a third fully-controlled valve V44, a third uncontrolled valve V45, a third half-controlled valve V46 and a fourth half-controlled valve V47; the first fully-controlled valve V42 and the second uncontrolled valve V43, the third fully-controlled valve V44 and the third uncontrolled valve V45, the third half-controlled valve V46 and the fourth half-controlled valve V47 are connected in parallel; the B-phase upper bridge arm circuit 1 includes a first half-controlled valve V61, a first fully-controlled valve V62, a second uncontrolled valve V63, a third fully-controlled valve V64, a third uncontrolled valve V65, a third half-controlled valve V66 and a fourth half-controlled valve V67. Valve V67; the first fully-controlled valve V62 and the second uncontrolled valve V63 connected in series, the third fully-controlled valve V64 and the third uncontrolled valve V65 connected in series, the third half-controlled valve V66 and the fourth half-controlled valve V67 connected in parallel; the C phase upper bridge arm circuit 1 includes the first half-controlled valve V21, the first fully-controlled valve V22, the second uncontrolled valve V23, the third fully-controlled valve V24, the third uncontrolled valve V25, the third half-controlled valve V26 and the fourth half-controlled valve V27; the first fully-controlled valve V22 and the second uncontrolled valve V23, the third fully-controlled valve V24 and the third uncontrolled valve V25 connected in series, the third half-controlled valve V26 and the fourth half-controlled valve V27 connected in parallel; the A phase lower bridge arm Circuit 2 includes a first half-controlled valve V11, a first fully-controlled valve V12, a second uncontrolled valve V13, a third fully-controlled valve V14, a third uncontrolled valve V15, a third half-controlled valve V16 and a fourth half-controlled valve V17; the first fully-controlled valve V12 and the second uncontrolled valve V13, the third fully-controlled valve V14 and the third uncontrolled valve V15, the third half-controlled valve V16 and the fourth half-controlled valve V17 connected in series are connected in parallel; the B-phase lower bridge arm circuit 2 includes a first half-controlled valve V31, a first fully-controlled valve V32, a second uncontrolled valve V33, a third fully-controlled valve V34, a third uncontrolled valve V35, a third half-controlled valve V36 and a fourth half-controlled valve V37; the first fully-controlled valve V12 and the second uncontrolled valve V13 connected in series, the third fully-controlled valve V14 and the third uncontrolled valve V15 connected in series, the third half-controlled valve V16 and the fourth half-controlled valve V17 connected in parallel. The controlled valve V32 and the second uncontrolled valve V33, the third fully controlled valve V34 and the third uncontrolled valve V35 connected in series, the third half-controlled valve V36 and the fourth half-controlled valve V37 are connected in parallel; the C phase lower bridge arm circuit 2 includes the first half-controlled valve V51, the first fully controlled valve V52, the second uncontrolled valve V53, the third fully controlled valve V54, the third uncontrolled valve V55, the third half-controlled valve V56 and the fourth half-controlled valve V57; the first fully controlled valve V52 and the second uncontrolled valve V53, the third fully controlled valve V54 and the third uncontrolled valve V55 connected in series, the third half-controlled valve V56 and the fourth half-controlled valve V57 are connected in parallel; the above-mentioned third half-controlled valve and fourth half-controlled valve adopt Figure 7B The one-way half-controlled switch shown is composed of thyristors connected in series, or the third half-controlled valve and the fourth half-controlled valve are combined into Figure 7C The bidirectional half-controlled switch shown.

[0145] In some embodiments, each first fully-controlled valve and each second fully-controlled valve is connected in parallel with a lightning arrester, and / or each first half-controlled valve, each second half-controlled valve or each first uncontrolled valve is connected in parallel with a lightning arrester.

[0146] In some embodiments, reference Fig.16 ,exist Fig.14 On the basis of, each first fully-controlled valve, the second fully-controlled valve, each first half-controlled valve and each second uncontrolled valve are connected in parallel with a lightning arrester, for example, the first half-controlled valve V41 of the upper bridge arm circuit 1 of phase A is connected in parallel with the lightning arrester F41, the first fully-controlled valve V42 is connected in parallel with the lightning arrester F42, and the second uncontrolled valve V43 is connected in parallel with the lightning arrester F43; the first half-controlled valve V11 of the lower bridge arm circuit 2 of phase A is connected in parallel with the lightning arrester F11, the first fully-controlled valve V12 is connected in parallel with the lightning arrester F12, and the second uncontrolled valve V13 is connected in parallel with the lightning arrester F13; the first half-controlled valve V61 of the upper bridge arm circuit 1 of phase B is connected in parallel with the lightning arrester F61, the first fully-controlled valve V62 is connected in parallel with the lightning arrester F62, and the second uncontrolled valve V63 is connected in parallel with the lightning arrester F6 3; the first half-controlled valve 31 of the B-phase lower bridge arm circuit 2 is connected in parallel with a lightning arrester F31, the first fully-controlled valve V32 is connected in parallel with a lightning arrester F32, and the second uncontrolled valve V33 is connected in parallel with a lightning arrester F33; the first half-controlled valve V21 of the C-phase upper bridge arm circuit 1 is connected in parallel with a lightning arrester F21, the first fully-controlled valve V22 is connected in parallel with a lightning arrester F22, and the second uncontrolled valve V23 is connected in parallel with a lightning arrester F23; the first half-controlled valve 51 of the C-phase lower bridge arm circuit 2 is connected in parallel with a lightning arrester F51, the first fully-controlled valve V52 is connected in parallel with a lightning arrester F52, and the second uncontrolled valve V53 is connected in parallel with a lightning arrester F53; the second fully-controlled valve V71 of the shut-off circuit 3 is connected in parallel with a lightning arrester F71, and the second half-controlled valve V72 is connected in parallel with a lightning arrester F72.

[0147] The present invention provides a centralized controllable shutdown grid-commutated converter control method, which is executed by an electronic device, wherein the electronic device can be a control device, a server, or a terminal device. The control device can be 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.

[0148] Reference Fig.17 A centralized controllable shutdown grid commutation converter control method includes: step S101, step S102 and step S103, wherein:

[0149] S101. When operating parameter information of a centralized controllable off-grid phase-commutating converter is obtained, inverter state control information is generated based on the parameter information, and a main circuit is controlled to operate in an inverter state based on the inverter state control information.

[0150] In some embodiments, the electronic device monitors the operating status of the centralized controllable off-grid phase-commutating converter in real time, and obtains operating parameter information of the operating status of the centralized controllable off-grid phase-commutating converter, such as AC voltage, DC current, etc. When the electronic device obtains the operating status of the centralized controllable off-grid phase-commutating converter, the electronic device generates inverter state control information, such as a trigger pulse, and the centralized controllable off-grid phase-commutating converter operates in an inverter state based on the inverter state control information, that is, the first half-controlled valve and the first fully-controlled valve of different upper bridge arm circuits or lower bridge arm circuits at different times are controlled to be turned on at the same time; for example, in a certain time period within the AC voltage cycle, the electronic device controls the first half-controlled valve V41 and the first fully-controlled valve V42 of the A-phase upper bridge arm circuit 1, and the first half-controlled valve V31 and the first fully-controlled valve V32 of the B-phase lower bridge arm circuit 2 to be turned on, and operates in an inverter state according to the six-pulse inverter working mode.

[0151] When the first fully controlled valve is composed of switches in series with submodules and a lightning arrester or an absorption circuit in parallel so that it has the ability to continuously shut off current, the first fully controlled valve is shut off during commutation to provide additional commutation voltage and force the current to be shut off, thereby reducing the shutoff angle and reducing the reactive power loss of the centralized controllable shutoff grid commutation converter. Figure 7K The half-bridge sub-modules shown are connected in series. When the A-phase upper bridge arm circuit and the B-phase upper bridge arm are switched, the A-phase voltage is lower than the B-phase voltage during the switching period, and the first full-control valve V42 is controlled to be closed. The half-bridge sub-module of the first full-control valve V42 is charged and provides an additional switching voltage, so that the A-phase voltage is higher than the B-phase voltage, forcing the current to switch from the A-phase to the B-phase, and then the first half-control valve V41 is controlled to reverse conduction to release the charge of the capacitor in the half-bridge sub-module.

[0152] S102. When the commutation fault information is obtained, a first on-command and a first off-command are generated, and based on the first on-command, the other bridge arm circuit of the same phase as the commutation bridge arm is controlled to be reversely conducted and the off-circuit of the auxiliary circuit is controlled to be conducted; based on the first off-command, the first full-control valve of the commutation bridge arm is controlled to be turned off.

[0153] In some embodiments, the commutation fault information includes fault information that causes the natural commutation failure of the commutation bridge arm of the main circuit. The above-mentioned commutation fault information includes an AC system fault or a DC system fault connected to the centralized controllable shutdown grid commutation converter. The AC system fault can be judged according to the increase of the zero-sequence component of the AC voltage, the sudden change of the AC voltage, the drop of the AC voltage amplitude, the increase of the AC voltage harmonics, and the increase of the DC current. The DC system fault can be judged according to the drop of the DC voltage and the increase of the DC current, but it is not limited to this.

[0154] 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 second half-controlled valve and the third half-controlled valve, the grid-side or valve-side AC current and AC voltage. If the second half-controlled valve and the third 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.

[0155] When the commutation fault information is obtained, the electronic device generates a first turn-on instruction and a first turn-off instruction. Subsequently, based on the first turn-on instruction, the electronic device controls the other bridge arm circuit of the same phase of the commutation bridge arm to reverse conduct and controls the turn-on of the turn-off circuit of the auxiliary circuit, and controls the turn-off of the first full-control valve of the commutation bridge arm based on the first turn-off instruction. For example, when the A-phase upper bridge arm circuit and the B-phase upper bridge arm circuit are commutated, the A-phase upper bridge arm circuit is the commutation bridge arm, and the B-phase upper bridge arm circuit is the bridge arm to be commutated, and when the commutation fault information is obtained, the A-phase lower bridge arm circuit is controlled to reverse conduct and the turn-off circuit is controlled to conduct, and at the same time, the first full-control valve of the A-phase upper bridge arm circuit is controlled to turn-off, so that the current of the A-phase upper bridge arm is transferred to the A-phase lower bridge arm circuit and the turn-off circuit.

[0156] In the case of insufficient commutation margin, the natural commutation failure of the commutation bridge arm of the main circuit may occur. For example, when the A-phase upper bridge arm circuit and the B-phase upper bridge arm are commutating, if the A-phase voltage is lower than the B-phase voltage during commutation, the AC voltage cannot be used for commutation normally, which may cause the natural commutation failure of the A-phase upper bridge arm of the main circuit.

[0157] S103, when the first half-controlled valve of the commutation bridge arm of the main circuit resumes shutting down, a second shut-down instruction is generated to control the shut-down circuit of the auxiliary circuit to shut down.

[0158] In some embodiments, when the electronic device detects that the first half-controlled valve of the commutation bridge arm of the main circuit has resumed closing, a second shutdown instruction is generated, and the centralized controllable shutdown grid commutation converter responds to the second shutdown instruction, controls the shutdown circuit corresponding to the commutation bridge arm to shut down, and transfers the current from the phase where the commutation bridge arm is located to the phase to be commutated, effectively suppressing the occurrence of commutation failure; for example, when the electronic device detects that the first half-controlled valve of the upper bridge arm circuit of phase A of the main circuit has resumed closing, the second shutdown instruction is generated, and the centralized controllable shutdown grid commutation converter responds to the second shutdown instruction, controls the shutdown circuit to shut down, and provides sufficient commutation voltage to transfer the current from the upper bridge arm circuit of phase A to the upper bridge arm circuit of phase B.

[0159] In some embodiments, the recovery and shutdown of the first half-controlled valve included in the phase-changing bridge arm of the main circuit is determined based on the reverse recovery time of the first half-controlled valve, and the reverse recovery time is greater than or equal to the reverse recovery time of the thyristor included in the first half-controlled valve, wherein the typical value of the reverse recovery time of the thyristor is 200~800us, and the typical value of the reverse recovery time of the first half-controlled valve is 200us~1.5ms.

[0160] In some embodiments, when the second full-control valve is over-voltage or fails, the upper bridge arm circuit and the lower bridge arm circuit of one phase of electricity are controlled to be turned on, such as the A-phase upper bridge arm circuit and the A-phase lower bridge arm circuit.

[0161] In some embodiments, a third half-controlled valve is connected in parallel at both ends of the first fully-controlled valve, or a third half-controlled valve is connected in parallel at both ends of the first fully-controlled valve and the second uncontrolled valve in series, and when the first fully-controlled valve is over-pressured or fails, the third half-controlled valve is controlled to be conductive.

[0162] In some embodiments, when the shut-off circuit of the auxiliary circuit and the anode bus of the main circuit are connected through an isolating switch and / or a knife switch, and the cathode bus of the main circuit is connected through an isolating switch and / or a knife switch, and in the event of a shut-off circuit failure, the isolating switch and / or the knife switch are separated.

[0163] In some embodiments, a fourth half-controlled valve is connected in parallel at both ends of the third fully-controlled valve or a fourth half-controlled valve is connected in parallel at both ends of the third fully-controlled valve and the third uncontrolled valve in series, and when the third fully-controlled valve is over-pressured or fails, the fourth half-controlled valve is controlled to be turned on.

[0164] In some embodiments, when at least one phase upper bridge arm circuit and at least one phase lower bridge arm circuit both further include a third fully-controlled valve and the shutdown circuit of the control auxiliary circuit is shut down, the third fully-controlled valve is controlled to be shut down.

[0165] In some embodiments, according to the above control method, the first fully-controlled valve needs to have the rated current or overload current flow capacity. However, in the event of a fault in the DC power transmission system, the first fully-controlled valve only needs to provide a smaller shut-off voltage to transfer the fault current to the shut-off circuit and another bridge arm circuit of the same phase as the commutation bridge arm. The second fully-controlled valve only works when the commutation fault information is obtained, and it is necessary 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 second fully-controlled valve is shut off, the current will be transferred to the parallel lightning arrester, which will provide the shut-off voltage and absorb energy. The shut-off circuit and lightning arrester of the present invention are centrally configured, and whether it is an asymmetric AC fault or a symmetric AC fault, it is absorbed by the same lightning arrester, which improves the utilization rate of the lightning arrester and thus improves the ability to resist commutation failure.

[0166] According to some embodiments, when the semiconductor device in the bidirectional half-controlled switch of the first half-controlled valve of the centralized controllable off grid-commutated converter is subjected to forward and reverse voltage exceeding the limit, the bidirectional half-controlled switch is controlled to conduct forward and reverse.

[0167] In some embodiments, reference Figure 8 Taking the A-phase upper bridge arm circuit of the main circuit as an example, when the A-phase upper bridge arm circuit switches to the B-phase upper bridge arm circuit, at this time, when the switching fault information is obtained, the first half-controlled valve V11 of the A-phase lower bridge arm circuit is controlled to be reversely conducted, and the second full-controlled valve V71 of the shutdown circuit of the auxiliary circuit is controlled to be turned on; the first full-controlled valve V42 of the A-phase upper bridge arm circuit is controlled to be shut down, so that the current of the A-phase upper bridge arm circuit is transferred to the A-phase lower bridge arm circuit and the shutdown circuit of the auxiliary circuit; after the first half-controlled valve V41 of the A-phase upper bridge arm circuit of the main circuit resumes shutdown, the second full-controlled valve V71 of the shutdown circuit of the auxiliary circuit is controlled to be shut down, thereby realizing the current transfer from the A-phase upper bridge arm circuit to the B-phase upper bridge arm circuit.

[0168] In some embodiments, reference Fig. 9 Taking the A-phase upper bridge arm circuit of the main circuit as an example, when the A-phase upper bridge arm circuit switches to the B-phase upper bridge arm circuit, if the switching fault information is obtained, the first half-controlled valve V11 and the first full-controlled valve V12 of the A-phase lower bridge arm circuit are controlled to be reversely conducted, and the second full-controlled valve V71 of the shutdown circuit of the auxiliary circuit is controlled to be conducted; the first full-controlled valve V42 of the A-phase upper bridge arm circuit is controlled to be shut down, so that the current of the A-phase upper bridge arm circuit is transferred to the A-phase lower bridge arm circuit and the shutdown circuit of the auxiliary circuit; after the first half-controlled valve V41 of the A-phase upper bridge arm circuit of the main circuit resumes shutdown, the second full-controlled valve V71 of the shutdown circuit of the auxiliary circuit is controlled to be shut down, so that the current is transferred from the A-phase upper bridge arm circuit to the B-phase upper bridge arm circuit.

[0169] In some embodiments, reference Fig.10 Taking the A-phase upper bridge arm of the main circuit as an example, when the A-phase upper bridge arm circuit switches to the B-phase upper bridge arm circuit, if the switching fault information is obtained, the first half-controlled valve V11 of the A-phase lower bridge arm circuit is controlled to be reversely conducted, and the second full-controlled valve V71 and the second half-controlled valve V72 of the shutdown circuit of the auxiliary circuit are controlled to be turned on; the first full-controlled valve V42 of the A-phase upper bridge arm circuit is controlled to be shut down, so that the current of the A-phase upper bridge arm circuit is transferred to the A-phase lower bridge arm circuit and the shutdown circuit of the auxiliary circuit; after the first half-controlled valve V41 of the A-phase upper bridge arm circuit of the main circuit resumes shutdown, the second full-controlled valve V71 of the shutdown circuit of the auxiliary circuit is controlled to be shut down, so that the current is transferred from the A-phase upper bridge arm circuit to the B-phase upper bridge arm circuit.

[0170] In some embodiments, reference Fig.11Taking the A-phase upper bridge arm circuit of the main circuit as an example, when the A-phase upper bridge arm circuit switches to the B-phase upper bridge arm circuit, if the switching fault information is obtained, the first half-controlled valve V11 and the second uncontrolled valve V13 of the A-phase lower bridge arm circuit are controlled to be reversely conducted, and the second full-controlled valve V71 of the shutdown circuit of the auxiliary circuit is controlled to be turned on; the first full-controlled valve V42 of the A-phase upper bridge arm circuit is controlled to be shut down, so that the current of the A-phase upper bridge arm circuit is transferred to the A-phase lower bridge arm circuit and the shutdown circuit of the auxiliary circuit; after the first half-controlled valve V41 of the A-phase upper bridge arm circuit of the main circuit resumes shutdown, the second full-controlled valve V71 of the shutdown circuit of the auxiliary circuit is controlled to be shut down, so that the current is transferred from the A-phase upper bridge arm circuit to the B-phase upper bridge arm circuit.

[0171] In some embodiments, reference Fig.12 Taking the A-phase upper bridge arm circuit of the main circuit as an example, when the A-phase upper bridge arm circuit switches to the B-phase upper bridge arm circuit, if the switching fault information is obtained, the first half-controlled valve V11 of the A-phase lower bridge arm circuit is controlled to be reversed and the third full-controlled valve V14 is controlled to be turned on, and the second full-controlled valve V71 of the shutdown circuit of the auxiliary circuit is controlled to be turned on; the first full-controlled valve V42 of the A-phase upper bridge arm circuit is controlled to be turned off, so that the current of the A-phase upper bridge arm circuit is transferred to the A-phase lower bridge arm circuit and the shutdown circuit of the auxiliary circuit; after the first half-controlled valve V41 of the A-phase upper bridge arm circuit of the main circuit is restored to be shut down, the second full-controlled valve V71 and the third full-controlled valve V14 of the shutdown circuit of the auxiliary circuit are controlled to be shut down, so that the current is transferred from the A-phase upper bridge arm circuit to the B-phase upper bridge arm circuit.

[0172] In some embodiments, reference Fig.13 Taking the A-phase upper bridge arm circuit of the main circuit as an example, when the A-phase upper bridge arm circuit switches to the B-phase upper bridge arm circuit, if the switching fault information is obtained, the first half-controlled valve V11 and the third half-controlled valve V16 of the A-phase lower bridge arm circuit are controlled to be reversely conducted, and the second full-controlled valve V71 of the shutdown circuit of the auxiliary circuit is controlled to be conducted; the first full-controlled valve V42 of the A-phase upper bridge arm circuit is controlled to be shut down, so that the current of the A-phase upper bridge arm circuit is transferred to the A-phase lower bridge arm circuit and the shutdown circuit of the auxiliary circuit; after the first half-controlled valve V41 of the A-phase upper bridge arm circuit of the main circuit resumes shutdown, the second full-controlled valve V71 of the shutdown circuit of the auxiliary circuit is controlled to be shut down, so that the current is transferred from the A-phase upper bridge arm circuit to the B-phase upper bridge arm circuit; in the case of overvoltage or failure of the first full-controlled valve V42, the third half-controlled valve V46 is controlled to be forwardly conducted, and replaces the first full-controlled valve V42 to work.

[0173] In some embodiments, reference Fig.14 and Fig.16Taking the A-phase upper bridge arm circuit of the main circuit as an example, when the A-phase upper bridge arm circuit switches to the B-phase upper bridge arm circuit, if the switching fault information is obtained, the first half-controlled valve V11 and the third half-controlled valve V16 of the A-phase lower bridge arm circuit are controlled to be reversely conducted, and the second full-controlled valve V71 and the second half-controlled valve V72 of the shutdown circuit of the auxiliary circuit are controlled to be conducted; the first full-controlled valve V42 of the A-phase upper bridge arm circuit is controlled to be shut down, so that the current of the A-phase upper bridge arm circuit is transferred to the A-phase lower bridge arm circuit and the shutdown circuit of the auxiliary circuit; after the first half-controlled valve V41 of the A-phase upper bridge arm circuit of the main circuit resumes shutdown, the second full-controlled valve V71 of the shutdown circuit of the auxiliary circuit is controlled to be shut down, so that the current is transferred from the A-phase upper bridge arm circuit to the B-phase upper bridge arm circuit; in the case of overvoltage or failure of the first full-controlled valve V42, the third half-controlled valve V46 is controlled to be forwardly conducted, and replaces the first full-controlled valve V42 to work.

[0174] In some embodiments, reference Fig.15 Taking the A-phase upper bridge arm circuit of the main circuit as an example, when the A-phase upper bridge arm circuit switches phase to the B-phase upper bridge arm circuit, if the switching fault information is obtained, the first half-controlled valve V11 of the A-phase lower bridge arm circuit is controlled to be reversely conducted, the third full-controlled valve V14 is controlled to be turned on, and the second full-controlled valve V71 of the shutdown circuit of the auxiliary circuit is controlled to be turned on; the first full-controlled valve V42 of the A-phase upper bridge arm circuit is controlled to be turned off, so that the current of the A-phase upper bridge arm circuit is transferred to the A-phase lower bridge arm circuit and the shutdown circuit of the auxiliary circuit; wait for the A-phase upper bridge arm circuit of the main circuit to After the first half-controlled valve V41 of the circuit resumes shutdown, the second full-controlled valve V71 and the third full-controlled valve V14 of the shutdown circuit of the auxiliary circuit are controlled to shut down, thereby realizing the transfer of current from the A-phase upper bridge arm circuit to the B-phase upper bridge arm circuit; in the case of overvoltage or failure of the first full-controlled valve V42, the third half-controlled valve V46 is controlled to be forward-conducted and replaces the first full-controlled valve V42 to work; in the case of overvoltage or failure of the third full-controlled valve V14, the fourth half-controlled valve V17 is controlled to be conducted and replaces the third full-controlled valve V14 to work.

[0175] The control of the first half-controlled valve, the second half-controlled valve, the third half-controlled valve, the fourth half-controlled valve, the first full-controlled valve, the second full-controlled valve, and the third full-controlled valve is achieved by applying a trigger pulse, and when the valves are simultaneously subjected to a forward voltage, they will be in a conducting state. The control of the first half-controlled valve reverse conduction is achieved by applying a trigger pulse to the reverse thyristor, and when the valves are simultaneously subjected to a reverse voltage, they will be in a reverse conduction state.

[0176] In some embodiments, reference Fig.18 ,by Fig.17Based on the control method provided in , a flow chart of a centralized controllable shutdown grid-commutating converter control method is provided, wherein the main circuit is first controlled to operate in inverter mode, and then it is determined whether the commutating bridge arm fails in natural commutation. When it is determined that the commutating bridge arm does not fail in natural commutation, the main circuit continues to be controlled to operate in inverter mode. When it is determined that the commutating bridge arm will fail in natural commutation, the other bridge arm of the phase where the commutating bridge arm is located is controlled to be reversely conducted, the shutdown circuit of the auxiliary circuit is controlled to be conducted, and the first full-control valve of the commutating bridge arm is controlled to be shut down. Afterwards, after the commutating bridge arm resumes shutdown, the shutdown circuit of the auxiliary circuit is controlled to be shut down.

[0177] Reference Fig.19 The centralized controllable shutdown grid-commutated converter control device 20 may specifically include: a first control module 201, a second control module 202 and a third control module 203, wherein:

[0178] The first control module 201 is used to generate inverter state control information based on the parameter information when the operation parameter information of the centralized controllable off-grid phase-commutated converter is obtained, and control the main circuit to operate in the inverter state based on the inverter state control information;

[0179] The second control module 202 is used to generate a first on instruction and a first off instruction when the commutation fault information is obtained, and control the other bridge arm circuit of the same phase of the commutation bridge arm to reverse conduct based on the first on instruction and control the off circuit of the auxiliary circuit to conduct; control the first full-control valve of the commutation bridge arm to shut down based on the first off instruction;

[0180] The third control module 203 is used to generate a second shut-down instruction when the first half-controlled valve of the commutation bridge arm of the main circuit resumes shutting down, so as to control the shut-down circuit of the auxiliary circuit to shut down.

[0181] 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;

[0182] 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;

[0183] The third control module 203 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.

[0184] An embodiment of the present invention provides a high voltage direct current transmission system, including a centralized controllable shutdown grid commutation converter.

[0185] 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.

[0186] In some embodiments, part or all of the converters that need to be inverted in a two-terminal DC power transmission system or a multi-terminal DC power transmission system adopt the above-mentioned centralized controllable shutdown grid-commutated converter.

[0187] Reference Fig. 20 , Fig. 20 The structure of a single pole of a bipolar direct current transmission system is shown, and a single pole includes a first alternating current system 8, a first grid-commutated converter 4, a second grid-commutated converter 5, a first converter transformer 6, a second converter transformer 7, a direct current line 9, a second alternating current system 14, a first centralized controllable shutdown grid-commutated converter 10, a second centralized controllable shutdown grid-commutated converter 11, a third converter transformer 12 and a fourth converter transformer 13. In the case of positive power transmission, the AC power of the first AC system 8 passes through the first converter transformer 6 and the second converter transformer 7, and is rectified into DC power by the first grid phase-commutating converter 4 and the second grid phase-commutating converter 5, and is transmitted to the first centralized controllable shutdown grid phase-commutating converter 10 and the second centralized controllable shutdown grid phase-commutating converter 11 through the DC line 9, and is inverted into AC power, and is transmitted to the second AC system 14 after passing through the third converter transformer 12 and the fourth converter transformer 13, thereby realizing the transmission of DC power; the first centralized controllable shutdown grid phase-commutating converter 10 and the second centralized controllable shutdown grid phase-commutating converter 11 have the ability to suppress commutation failure, thereby ensuring the reliability of DC power transmission.

[0188] Reference Fig.21A , Fig.21A Shows Fig. 20 The single-phase ground fault test results of the second AC system 14 of the high-voltage direct current transmission system are shown, wherein the first centralized controllable shutdown grid-commutated converter 10 and the second centralized controllable shutdown grid-commutated converter 11 adopt Figure 8The valve structure shown. UAC_IN_L1, UAC_IN_L2 and UAC_IN_L3 are three-phase AC voltages; IVY_L1_SCA, IVY_L2_SCA and IVY_L3_SCA are three-phase valve-side AC currents; UDL_IN is a DC voltage; IDNC_IN is a DC current; MAIN_BRANCH_CP1, MAIN_BRANCH_CP2, MAIN_BRANCH_CP3, MAIN_BRANCH_CP4, MAIN_BRANCH_CP5 and MAIN_BRANCH_CP6 are respectively the trigger pulses of the forward semiconductor devices of the bidirectional half-controlled switches of the first half-controlled valves V11, V21, V31, V41, V51 and V61, the opening time of the first full-controlled valves V12, V22, V32, V42, V52 and V62 is the same as the trigger pulse of the first half-controlled valve, and the closing time is delayed based on the trigger pulse of the first half-controlled valve. AUX_BRANCH_CP1, AUX_BRANCH_CP2, AUX_BRANCH_CP3, AUX_BRANCH_CP4, AUX_BRANCH_CP5 and AUX_BRANCH_CP6 are respectively the trigger pulses of the reverse semiconductor devices of the bidirectional half-controlled switches of the first half-controlled valves V11, V21, V31, V41, V51 and V61, and the six signals are phase-ORed as the trigger pulse of the second fully-controlled valve V71. After a ground fault occurs in phase A of the AC system, the AC voltage UAC_IN_L1 becomes 0. When it is detected that the first half-controlled valve V11, V21, V31, V41, V51 or V61 may have a commutation failure, V41, V51, V61, V11, V21 or V31 is controlled to reverse conduction accordingly, the second fully-controlled valve V71 is controlled to be turned on, and the first fully-controlled valve V12, V22, V32, V42, V52 or V62 is controlled to be turned off accordingly, and the current is transferred to the second fully-controlled valve V71 and the first half-controlled valve V41, V51, V61, V11, V21 or V31. When the first half-controlled valve V11, V21, V31, V41, V51 or V61 resumes being turned off, the second fully-controlled valve V71 is controlled to be turned off. During the entire fault period, the valve-side AC currents IVY_L1_SCA, IVY_L2_SCA and IVY_L3_SCA can still be successfully commutated, the DC voltage UDL_IN is maintained at about 50%, and the DC current IDNC_IN can also maintain the pre-fault level fluctuation. The test results show that this topology can achieve self-commutation during a single-phase AC fault, maintain a certain power transmission, and will not fail to commutate. Fig. 21B , Fig. 21B Shows Fig. 20 The three-phase short-circuit fault test results of the second AC system 14 of the high-voltage direct current transmission system are shown, wherein the first centralized controllable shutdown grid-commutated converter 10 and the second centralized controllable shutdown grid-commutated converter 11 adopt Figure 8 The valve structure shown. After a short circuit fault occurs in the three phases of the AC system, the AC voltages UAC_IN_L1, UAC_IN_L2 and UAC_IN_L3 are all 0. During the entire fault period, the valve-side AC currents IVY_L1_SCA, IVY_L2_SCA and IVY_L3_SCA can still be successfully commutated, realizing self-commutation that does not rely on the AC voltage during the fault period and providing controlled short-circuit current. After the second fully-controlled valve V71 is turned off, since the AC voltage cannot provide a reverse voltage, the reverse half-controlled devices of the first half-controlled valves V11, V21, V31, V41, V51 or V61 are not turned off, and there is a certain amount of freewheeling current.

[0189] Reference Fig.22A , Fig.22A Shows Fig. 20 The single-phase ground fault test results of the second AC system 14 of the high-voltage direct current transmission system are shown, wherein the first centralized controllable shutdown grid-commutated converter 10 and the second centralized controllable shutdown grid-commutated converter 11 adopt Fig.12The valve structure shown. UAC_IN_L1, UAC_IN_L2 and UAC_IN_L3 are three-phase AC voltages; IVY_L1_SCA, IVY_L2_SCA and IVY_L3_SCA are three-phase valve-side AC currents; UDL_IN is a DC voltage; IDNC_IN is a DC current; MAIN_BRANCH_CP1, MAIN_BRANCH_CP2, MAIN_BRANCH_CP3, MAIN_BRANCH_CP4, MAIN_BRANCH_CP5 and MAIN_BRANCH_CP6 are respectively the trigger pulses of the forward semiconductor devices of the bidirectional half-controlled switches of the first half-controlled valves V11, V21, V31, V41, V51 and V61, the opening time of the first full-controlled valves V12, V22, V32, V42, V52 and V62 is the same as the trigger pulse of the first half-controlled valve, and the closing time is delayed based on the trigger pulse of the first half-controlled valve. AUX_BRANCH_CP1, AUX_BRANCH_CP2, AUX_BRANCH_CP3, AUX_BRANCH_CP4, AUX_BRANCH_CP5, AUX_BRANCH_CP6 are respectively the trigger pulses of the reverse semiconductor devices of the bidirectional half-controlled switches of the first half-controlled valves V11, V21, V31, V41, V51 and V61, and are also respectively the trigger pulses of the third fully-controlled valves V14, V24, V34, V44, V54 and V64; the six signals are phase-ORed as the trigger pulse of the second fully-controlled valve V71. After a ground fault occurs in phase A of the AC system, the AC voltage UAC_IN_L1 becomes 0. When it is detected that the first half-controlled valve V11, V21, V31, V41, V51 or V61 may have a commutation failure, V41, V51, V61, V11, V21 or V31 is controlled to be reversed, V44, V54, V64, V14, V24 or V34 is controlled to be turned on, the second fully-controlled valve V71 is controlled to be turned on, and the first fully-controlled valve V12, V22, V32, V42, V52 or V62 is controlled to be turned off, and the current is transferred to the second fully-controlled valve V71 and the first half-controlled valve V41, V51, V61, V11, V21 or V31. When the first half-controlled valve V11, V21, V31, V41, V51 or V61 is turned off, the second fully-controlled valve V71 is controlled to be turned off. During the entire fault period, the valve-side AC currents IVY_L1_SCA, IVY_L2_SCA and IVY_L3_SCA can still be successfully commutated, the DC voltage UDL_IN is maintained at about 50%, and the DC current IDNC_IN can also maintain the pre-fault level fluctuation. The test results show that this topology can achieve self-commutation during a single-phase AC fault, maintain a certain power transmission, and will not fail to commutate. Fig. 22B , Fig. 22B Shows Fig. 20The three-phase short-circuit fault test results of the second AC system 14 of the high-voltage direct current transmission system are shown, wherein the first centralized controllable shutdown grid-commutated converter 10 and the second centralized controllable shutdown grid-commutated converter 11 adopt Fig.12 The valve structure shown. After a short circuit fault occurs in the three phases of the AC system, the AC voltages UAC_IN_L1, UAC_IN_L2 and UAC_IN_L3 are all 0. During the entire fault period, the valve-side AC currents IVY_L1_SCA, IVY_L2_SCA and IVY_L3_SCA can still be successfully commutated, realizing self-commutation independent of the AC voltage during the fault period and providing controlled short-circuit current. After the second full-control valve V71 is turned off, the third full-control valve is also turned off, and there is no freewheeling current.

[0190] 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 centralized controllable shutdown grid commutation converter, characterized in that: include: A main circuit, comprising at least one-phase upper bridge arm circuit and at least one-phase lower bridge arm circuit, wherein one end of the at least one-phase upper bridge arm circuit is connected to the anode bus of the main circuit, the other end of the at least one-phase upper bridge arm circuit is connected to one end of the at least one-phase lower bridge arm circuit, and the other end of the at least one-phase lower bridge arm circuit is connected to the cathode bus of the main circuit; the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit both comprise a first half-controlled valve, and the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit both comprise a first fully-controlled valve or share a first fully-controlled valve; The auxiliary circuit includes a shut-down circuit, one end of which is connected to the anode bus of the main circuit, and the other end of which is connected to the cathode bus of the main circuit.

2. The centralized controllable shutdown grid-commutated converter according to claim 1, characterized in that: The shut-off circuit includes: a second fully controlled valve; One end of the second full-control valve is connected to the anode busbar of the main circuit, and the other end of the second full-control valve is connected to the cathode busbar of the main circuit; The second full-control valve includes at least one of a one-way full-control switch, a two-way full-control switch, and a sub-module series switch.

3. The centralized controllable shutdown grid-commutated converter according to claim 2, characterized in that: The shut-off circuit further comprises a second half-controlled valve and / or a first uncontrolled valve; The second half-controlled valve and / or the first uncontrolled valve are connected in series with the second fully-controlled valve; The second half-controlled valve includes a one-way half-controlled switch, and the first uncontrolled valve includes an uncontrolled switch.

4. The centralized controllable shutdown grid-commutated converter according to claim 3, characterized in that: The second fully-controlled valve is connected in parallel with a lightning arrester, and / or the second half-controlled valve and / or the first uncontrolled valve is connected in parallel with a lightning arrester.

5. The centralized controllable shutdown grid-commutated converter according to claim 1, characterized in that: The first half-controlled valve includes at least one of a bidirectional half-controlled switch, an anti-parallel uncontrolled switch and a unidirectional half-controlled switch; the first fully-controlled valve includes at least one of a unidirectional fully-controlled switch, a bidirectional fully-controlled switch and a sub-module series switch.

6. The centralized controllable shutdown grid-commutated converter according to claim 5, characterized in that: 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 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 uncontrolled switch is composed of semiconductor devices that are uncontrolled to be turned on and off in series, and the semiconductor devices that are uncontrolled to be turned on and off include but are not limited to diodes; 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, integrated gate-commutated thyristors, and reverse-blocking 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 transistors; 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 semiconductor devices of the half-bridge submodules, full-bridge submodules, quasi-full-bridge submodules, and clamped twin submodules include but are not limited to insulated gate bipolar transistors and integrated gate-commutated thyristors.

7. The centralized controllable shutdown grid-commutated converter according to claim 1, characterized in that: In the case where both the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit include a first fully-controlled valve, the first half-controlled valve and the first fully-controlled valve are connected in series.

8. The centralized controllable shutdown grid-commutated converter according to claim 7, characterized in that: One end of the first half-controlled valve of the at least one-phase upper bridge arm circuit is connected to the anode bus of the main circuit, and one end of the first full-controlled valve of the at least one-phase upper bridge arm circuit is connected to one end of the first full-controlled valve of the at least one-phase lower bridge arm circuit; one end of the first half-controlled valve of the at least one-phase lower bridge arm circuit is connected to the cathode bus of the main circuit; or, One end of the first full-control valve of the at least one-phase upper bridge arm circuit is connected to the anode bus of the main circuit, and one end of the first half-control valve of the at least one-phase upper bridge arm circuit is connected to one end of the first half-control valve of the at least one-phase lower bridge arm circuit; one end of the first full-control valve of the at least one-phase lower bridge arm circuit is connected to the cathode bus of the main circuit.

9. The centralized controllable shutdown grid-commutated converter according to claim 7, characterized in that: The at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit each further include a second uncontrolled valve, which is connected in series with the first fully-controlled valve; the second uncontrolled valve includes any one of an uncontrolled switch, an anti-parallel uncontrolled switch and a unidirectional half-controlled switch.

10. The centralized controllable shutdown grid-commutated converter according to claim 7, characterized in that: The first half-controlled valve is connected in parallel with a lightning arrester and / or the first full-controlled valve is connected in parallel with a lightning arrester.

11. The centralized controllable shutdown grid-commutated converter according to claim 7, characterized in that: A third half-control valve is connected in parallel at both ends of the first full-control valve; or, In the case where both the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit further include a second uncontrolled valve, a third half-controlled valve is connected in parallel to both ends of the first fully-controlled valve and the second uncontrolled valve connected in series; The third half-controlled valve includes at least one of a one-way half-controlled switch and a two-way half-controlled switch.

12. The centralized controllable shutdown grid-commutated converter according to claim 7, characterized in that: The at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit both further include a third fully-controlled valve and / or a third uncontrolled valve; when the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit both further include a third uncontrolled valve, the third fully-controlled valve and the third uncontrolled valve are connected in series, and are connected in anti-parallel to a series circuit consisting of the second uncontrolled valve and the first fully-controlled valve; The third fully-controlled valve includes at least one of a one-way fully-controlled switch, a two-way fully-controlled switch, and a sub-module series switch; and the third uncontrolled valve includes an uncontrolled switch.

13. The centralized controllable shutdown grid-commutated converter according to claim 12, characterized in that: The fourth half-control valve is connected in parallel at both ends of the third full-control valve; or, When the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit both include a third uncontrolled valve, a fourth half-controlled valve is connected in parallel at both ends of the third fully-controlled valve and the third uncontrolled valve in series; the fourth half-controlled valve includes a one-way half-controlled switch.

14. The centralized controllable shutdown grid-commutated converter according to claim 1, characterized in that: The first fully-controlled valve of the at least one-phase upper bridge arm circuit and the first fully-controlled valve of the at least one-phase lower bridge arm circuit are connected in parallel with an absorption circuit.

15. The centralized controllable shutdown grid-commutated converter according to claim 1, characterized in that: The shutoff circuit of the auxiliary circuit is connected to the anode busbar of the main circuit through an isolating switch and / or a knife switch, and is connected to the cathode busbar of the main circuit through an isolating switch and / or a knife switch.

16. The centralized controllable shutdown grid-commutated converter according to claim 1, characterized in that: The first fully-controlled valve and / or the first half-controlled valve further includes a reactor.

17. The centralized controllable shutdown grid-commutated converter according to any one of claims 1, characterized in that: In the case where the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit share a first full-control valve; one end of the first full-control valve is connected to the common end of the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit, and the other end of the first full-control valve is the output end.

18. The centralized controllable shutdown grid-commutated converter according to claim 17, characterized in that: A fifth half-controlled valve is connected in parallel at both ends of the first full-controlled valve, and the fifth half-controlled valve includes at least one of a one-way half-controlled switch and a two-way half-controlled switch.

19. The centralized controllable shutdown grid-commutated converter according to any one of claims 1 to 18, characterized in that: The first full-control valve and the third full-control valve are combined into one full-control valve including a two-way full-control switch; and / or, The third half-controlled valve and the fourth half-controlled valve are combined into a half-controlled valve including a bidirectional half-controlled switch.

20. A centralized controllable shutdown grid commutation converter control method, characterized in that: Used to control the centralized controllable shutdown grid-commutated converter according to any one of claims 1 to 19, comprising: In the case of obtaining the operating parameter information of the centralized controllable off-grid phase-commutated converter, generating the inverter state control information based on the parameter information, and controlling the main circuit to operate in the inverter state based on the inverter state control information; When the commutation fault information is obtained, a first on instruction and a first off instruction are generated, and based on the first on instruction, another bridge arm circuit of the same phase as the commutation bridge arm is controlled to be reversely conducted and the off circuit of the auxiliary circuit is controlled to be conducted; based on the first off instruction, the first full-control valve of the commutation bridge arm is controlled to be turned off; When the first half-controlled valve of the phase-changing bridge arm of the main circuit resumes shutting down, a second shut-down instruction is generated to control the shut-down circuit of the auxiliary circuit to shut down.

21. The method according to claim 20, characterized in that In the case where the first fully-controlled valve is composed of switches in series with submodules, or is connected in parallel with a lightning arrester, or is connected in parallel with an absorption circuit, the first fully-controlled valve is closed during commutation in normal operation to provide additional commutation voltage.

22. The method according to claim 20, characterized in that The recovery and shutdown of the first half-controlled valve of the commutation bridge arm of the main circuit is determined according to the reverse recovery time of the first half-controlled valve, and the reverse recovery time is greater than or equal to the reverse recovery time of the thyristor included in the first half-controlled valve.

23. The method according to claim 20, characterized in that In case of overpressure or failure of the second full-control valve, the upper bridge arm circuit and the lower bridge arm circuit of one phase of electricity are controlled to be turned on at the same time.

24. The method according to claim 20, characterized in that When a third half-controlled valve is connected in parallel at both ends of the first fully-controlled valve, or a third half-controlled valve is connected in parallel at both ends of the first fully-controlled valve and the second uncontrolled valve in series, and the first fully-controlled valve is over-pressured or fails, the third half-controlled valve is controlled to be conductive.

25. The method according to claim 20, characterized in that When the shut-off circuit of the auxiliary circuit is connected to the anode bus of the main circuit through an isolating switch and / or a knife switch, and the cathode bus of the main circuit is connected through an isolating switch and / or a knife switch, and the shut-off circuit fails, the isolating switch and / or the knife switch are separated.

26. The method according to claim 20, characterized in that When the semiconductor device in the bidirectional half-controlled switch of the first half-controlled valve of the centralized controllable off grid-commutated converter is subjected to a forward or reverse voltage exceeding a limit value, the bidirectional half-controlled switch is controlled to conduct in the forward or reverse direction.

27. The method according to any one of claims 20 to 26, characterized in that: When a fourth half-controlled valve is connected in parallel at both ends of the third fully-controlled valve, or a fourth half-controlled valve is connected in parallel at both ends of the third fully-controlled valve and the third uncontrolled valve in series, and the third fully-controlled valve is over-pressured or fails, the fourth half-controlled valve is controlled to be conductive.

28. The method according to claim 27, characterized in that When both the at least one-phase upper bridge arm circuit and the at least one-phase lower bridge arm circuit further include a third fully-controlled valve and the shutdown circuit of the control auxiliary circuit is shut down, the third fully-controlled valve is controlled to be shut down.

29. A centralized controllable shutdown grid commutation converter control device, characterized in that: Used to control the centralized controllable shutdown grid-commutated converter according to any one of claims 1 to 19, comprising: A first control module is used to generate inverter state control information based on the parameter information when the operation parameter information of the centralized controllable shutdown grid-commutated converter is obtained, and control the main circuit to operate in the inverter state based on the inverter state control information; A second control module is used to generate a first on-commutation instruction and a first off-commutation instruction when the commutation fault information is obtained, and control the other bridge arm circuit of the same phase of the commutation bridge arm to reverse conduct based on the first on-commutation instruction and control the off circuit of the auxiliary circuit to conduct; and control the first full-control valve of the commutation bridge arm to shut down based on the first off-commutation instruction; The third control module is used to generate a second shutdown instruction when the first half-controlled valve of the phase-changing bridge arm of the main circuit resumes shutdown, so as to control the shutdown circuit of the auxiliary circuit to shut down.

30. A high voltage direct current power transmission system, comprising the centralized controllable shutdown grid-commutated converter according to any one of claims 1 to 19.

31. The system according to claim 30, 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.

32. The system according to claim 31, 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 centralized controllable shutdown grid-commutated converter.

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