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

Abstract

The application provides a centralized controllable off-grid commutation converter, a control method and device and a system, and relates to the technical field of high-voltage direct current transmission.The centralized controllable off-grid commutation converter comprises a main circuit, at least one upper bridge arm circuit and at least one lower bridge arm circuit, one end of the at least one upper bridge arm circuit is connected with a main circuit anode bus, the other end of the at least one upper bridge arm circuit is connected with one end of the at least one lower bridge arm circuit, the other end of the at least one lower bridge arm circuit is connected with a main circuit cathode bus, the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each comprise a first half-controlled valve and each comprise a first fully-controlled valve or share a first fully-controlled valve, an auxiliary circuit comprises an off circuit, one end of the off circuit is connected with the main circuit anode bus, and the other end of the off circuit is connected with the main circuit cathode bus.The application can inhibit the occurrence of commutation failure and improve the reliability of high-voltage direct current transmission.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-voltage direct current transmission, in particular to a centralized controllable turn-off grid commutation converter, a control method and device, and a system. BACKGROUND

[0002] With the development of economy and the continuous improvement of technology, the high-voltage and ultra-high-voltage direct current transmission systems connected to the power grid are gradually increasing, but it also increases the hidden danger of safe operation of the power grid. For example, in the case of simultaneous commutation failure of multiple direct currents in a multi-infeed direct current system, there is a threat to the safe operation of the corresponding regional alternating current grid, and with the increasing proportion of new energy power generation in recent years, higher requirements are put forward for the stable operation of the direct current transmission system and the ability to suppress commutation failure.

[0003] The existing direct current transmission technology mainly uses a twelve-pulse circuit structure grid commutation converter and a modular multilevel circuit structure voltage source converter for high-voltage and ultra-high-voltage direct current transmission. In the twelve-pulse circuit structure grid commutation converter, each twelve-pulse circuit has two three-phase six-bridge arm bridge circuits connected in series or parallel, and each bridge arm uses a single large-capacity thyristor in series. In the modular multilevel circuit structure voltage source converter, the modular multilevel circuit is a three-phase six-bridge arm bridge circuit, and each bridge arm uses a half-bridge sub-module structure and / or a full-bridge sub-module structure in series. In addition, replacing and adding auxiliary circuits to form a controllable turn-off grid commutation converter based on the existing grid commutation converter to solve the commutation failure problem has also become an important direction of direct current transmission technology research.

[0004] However, the existing twelve-pulse circuit structure grid commutation converter has the problem of commutation failure; the existing modular multilevel circuit structure voltage source converter has the problems of small device capacity, high cost, and large loss. The existing controllable turn-off grid commutation converter that uses full-controlled devices to suppress commutation failure has small device capacity and reliability that needs to be verified; the existing controllable turn-off grid commutation converter that suppresses commutation failure by adding auxiliary circuits has a complex structure and reduced reliability; the above two kinds of controllable turn-off grid commutation converters rely on lightning arresters to absorb energy when forced to turn off, and need to be equipped with equal lightning arresters for each bridge arm. In the case of single-phase grounding and other faults with a high probability, only the lightning arresters of the faulty phase will act, resulting in low utilization of the lightning arresters. Since the lightning arresters can only absorb energy for a short time, the lightning arresters generally cannot act in steady-state operation, so the grid commutation voltage still needs to be relied on for commutation, resulting in that the minimum turn-off angle cannot be controlled too small, and still a lot of reactive power needs to be consumed. SUMMARY

[0005] In order to inhibit the occurrence of high-voltage direct current transmission commutation failure, reduce the cost of controllable blocking grid commutation converter, improve the reliability of high-voltage direct current transmission, and reduce the reference value of blocking angle, and reduce the consumed reactive power, the application provides a centralized controllable blocking grid commutation converter, a control method and device, and a system.

[0006] The application provides a centralized controllable blocking grid commutation converter, which adopts the following technical scheme:

[0007] The application provides a centralized controllable blocking grid commutation converter, which adopts the following technical scheme:

[0008] The main circuit comprises at least one upper bridge arm circuit and at least one lower bridge arm circuit, one end of the at least one upper bridge arm circuit is connected with a main circuit anode bus, the other end of the at least one upper bridge arm circuit is connected with one end of the at least one lower bridge arm circuit, and the other end of the at least one lower bridge arm circuit is connected with a main circuit cathode bus; the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each comprise a first half-controlled valve, and the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each comprise a first fully-controlled valve or share one first fully-controlled valve.

[0009] The auxiliary circuit comprises a blocking circuit, one end of the blocking circuit is connected with the main circuit anode bus, and the other end of the blocking circuit is connected with the main circuit cathode bus.

[0010] According to some embodiments, the blocking circuit comprises a second fully-controlled valve, one end of the second fully-controlled valve is connected with the main circuit anode bus, and the other end of the second fully-controlled valve is connected with the main circuit cathode bus.

[0011] The second fully-controlled valve comprises at least one of a unidirectional fully-controlled switch, a bidirectional fully-controlled switch, and a submodule series switch.

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

[0013] The second half-controlled valve comprises a unidirectional half-controlled switch, and the first non-controlled valve comprises a non-controlled switch.

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

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

[0016] According to some embodiments, the bidirectional half-controlled switch is composed of a controllable turn-on but uncontrollable turn-off semiconductor device connected in anti-parallel and then connected in series, and the controllable turn-on but uncontrollable turn-off semiconductor device includes but is not limited to a thyristor;

[0017] The unidirectional half-controlled switch is composed of controllable turn-on but uncontrollable turn-off semiconductor devices connected in series, and the controllable turn-on but uncontrollable turn-off semiconductor devices include but are not limited to thyristors;

[0018] The uncontrolled switch is composed of controllable turn-on and turn-off semiconductor devices connected in series, and the controllable turn-on and turn-off semiconductor devices include but are not limited to diodes;

[0019] The unidirectional fully-controlled switch is composed of semiconductor devices with unidirectional turn-off capability connected in series, and the semiconductor devices with unidirectional turn-off 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 turn-off capability connected in series, and the semiconductor devices with bidirectional turn-off capability include but are not limited to reverse blocking integrated gate-commutated thyristors connected in anti-parallel;

[0021] The sub-module series switch is composed of sub-modules connected in series, and the sub-modules include but are not limited to half-bridge sub-modules, full-bridge sub-modules, full-bridge-like sub-modules, and clamped double sub-modules, and the semiconductor devices of the half-bridge sub-modules, full-bridge sub-modules, full-bridge-like sub-modules, and clamped double sub-modules include but are not limited to insulated gate bipolar transistors and integrated gate-commutated thyristors.

[0022] According to some embodiments, in the case that the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each 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 upper bridge arm circuit is connected to the main circuit anode bus, and one end of the first fully-controlled valve of the at least one upper bridge arm circuit is connected to one end of the first fully-controlled valve of the at least one lower bridge arm circuit; one end of the first half-controlled valve of the at least one lower bridge arm circuit is connected to the main circuit cathode bus; or,

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

[0025] According to some embodiments, the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each further comprise a second uncontrolled valve connected in series with the first controlled valve; the second uncontrolled valve comprises any one of an uncontrolled switch, an uncontrolled switch in anti-parallel connection, and a unidirectional semi-controlled switch.

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

[0027] According to some embodiments, the first controlled valve is connected in parallel with a third semi-controlled valve at both ends thereof; or,

[0028] In the case where the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each further comprise a second uncontrolled valve, a third semi-controlled valve is connected in parallel at both ends of the series connection of the first controlled valve and the second uncontrolled valve.

[0029] The third semi-controlled valve comprises at least one of a unidirectional semi-controlled switch and a bidirectional semi-controlled switch.

[0030] According to some embodiments, the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each further comprise a third controlled valve and / or a third uncontrolled valve, in the case where the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each further comprise a third uncontrolled valve, the third controlled valve and the third uncontrolled valve are connected in series, and are connected in anti-parallel connection with the series connection of the second uncontrolled valve and the first controlled valve.

[0031] The third controlled valve comprises at least one of a unidirectional controlled switch, a bidirectional controlled switch, and a sub-module series switch; the third uncontrolled valve comprises an uncontrolled switch.

[0032] According to some embodiments, the third controlled valve is connected in parallel with a fourth semi-controlled valve at both ends thereof; or,

[0033] In the case where the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each further comprise a third uncontrolled valve, a fourth semi-controlled valve is connected in parallel at both ends of the series connection of the third controlled valve and the third uncontrolled valve; the fourth semi-controlled valve comprises a unidirectional semi-controlled switch.

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

[0035] According to some embodiments, in the case where the at least one upper bridge arm circuit and the at least one lower bridge arm circuit share one first controlled valve; one end of the first controlled valve is connected with a common terminal of the at least one upper bridge arm circuit and the at least one lower bridge arm circuit, and the other end of the first controlled valve is an output terminal.

[0036] According to some embodiments, the first fully-controlled valve is connected in parallel with a fifth semi-controlled valve at both ends, and the fifth semi-controlled valve comprises at least one of a unidirectional semi-controlled switch and a bidirectional semi-controlled switch.

[0037] According to some embodiments, the turn-off circuit of the auxiliary circuit and the anode bus of the main circuit are connected through a disconnecting switch and / or a knife switch, and the cathode bus of the main circuit is connected through a disconnecting switch and / or a knife switch.

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

[0039] According to some embodiments, the first fully-controlled valve and the third fully-controlled valve are combined as one fully-controlled valve comprising a bidirectional fully-controlled switch; and / or,

[0040] The third semi-controlled valve and the fourth semi-controlled valve are combined as one semi-controlled valve comprising a bidirectional semi-controlled switch.

[0041] The application provides a control method of a centralized controllable turn-off grid commutation converter, adopting the following technical scheme:

[0042] A centralized controllable turn-off grid commutation converter control method is used to control the centralized controllable turn-off grid commutation converter, comprising:

[0043] In the case of obtaining the operating parameter information of the centralized controllable turn-off grid commutation converter, the inverter state control information is generated based on the parameter information, and the main circuit is controlled to operate in the inverter state based on the inverter state control information;

[0044] In the case of obtaining the commutation fault information, the first turn-on instruction and the first turn-off instruction are generated, and the other lower bridge arm circuit of the same phase of the commutation bridge arm is controlled to be reversely turned on and the turn-off circuit of the auxiliary circuit is controlled to be turned on based on the first turn-on instruction; the first fully-controlled valve of the commutation bridge arm is controlled to be turned off based on the first turn-off instruction;

[0045] In the case of the first semi-controlled valve of the commutation bridge arm of the main circuit recovering turn-off, the second turn-off instruction is generated, and the turn-off circuit of the auxiliary circuit is controlled to be turned off.

[0046] According to some embodiments, in the case that the first fully-controlled valve is composed of a sub-module series switch, or is connected in parallel with a lightning arrester, or is connected in parallel with an absorption circuit, additional commutation voltage is provided by the first fully-controlled valve turn-off during commutation in normal operation.

[0047] According to some embodiments, the first semi-controlled valve recovery turn-off of the phase-changing bridge arm of the main circuit is determined according to the reverse recovery time of the first semi-controlled valve, and the reverse recovery time is greater than or equal to the reverse recovery time of the thyristor contained in the first semi-controlled valve.

[0048] According to some embodiments, in the case of overvoltage 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, in the case of overvoltage or failure of the first fully-controlled valve, a third semi-controlled valve is connected in parallel across the first fully-controlled valve, or a third semi-controlled valve is connected in parallel across the first fully-controlled valve and the third non-controlled valve connected in series, and the third semi-controlled valve is controlled to be turned on.

[0050] According to some embodiments, in the case of failure of the shutdown circuit of the auxiliary circuit and the anode bus of the main circuit being connected through a disconnector and / or a knife switch and the cathode bus of the main circuit being connected through a disconnector and / or a knife switch, the disconnector and / or the knife switch is separated.

[0051] According to some embodiments, in the case of the semiconductor device in the bidirectional semi-controlled switch of the first semi-controlled valve of the centralized controllable shutdown grid phase-changing converter bearing a forward voltage or a reverse voltage exceeding a limit value, the bidirectional semi-controlled switch is controlled to be turned on in a forward direction or a reverse direction.

[0052] According to some embodiments, in the case of overvoltage or failure of the third fully-controlled valve, a fourth semi-controlled valve is connected in parallel across the third fully-controlled valve, or a fourth semi-controlled valve is connected in parallel across the third fully-controlled valve and the third non-controlled valve connected in series, and the fourth semi-controlled valve is controlled to be turned on.

[0053] According to some embodiments, in the case of the shutdown circuit of the auxiliary circuit being controlled to be turned off, the third fully-controlled valve is controlled to be turned off, and the upper bridge arm circuit and the lower bridge arm circuit of at least one phase each further include a third fully-controlled valve and a third non-controlled valve.

[0054] The application provides a centralized controllable shutdown grid phase-changing converter control device, which adopts the following technical scheme:

[0055] A centralized controllable shutdown grid phase-changing converter control device is used for controlling the centralized controllable shutdown grid phase-changing converter, comprising a first control module, a second control module, and a third control module, wherein,

[0056] The first control module is used for generating inverter state control information based on the parameter information when the operating parameter information of the centralized controllable shutdown grid phase-changing converter is acquired, and controlling the main circuit to operate in an inverter state based on the inverter state control information.

[0057] The second control module is configured to generate a first conduction instruction and a first turn-off instruction when the commutation failure information is acquired, and control another lower bridge arm circuit of the same phase of the commutation bridge arm to conduct reversely and control the turn-off circuit of the auxiliary circuit to conduct based on the first conduction instruction; and control the first fully-controlled valve of the commutation bridge arm to turn off based on the first turn-off instruction.

[0058] The third control module is configured to generate a second turn-off instruction when the first half-controlled valve of the commutation bridge arm of the main circuit recovers to turn off, and control the turn-off circuit of the auxiliary circuit to turn off.

[0059] The application provides a high-voltage direct current transmission system comprising the centralized controllable turn-off grid commutation 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 comprises a single-pole 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 inverters required to operate in reverse in the two-terminal direct current transmission system or the multi-terminal direct current transmission system adopt the centralized controllable turn-off grid commutation converter.

[0062] In summary, the application has the following beneficial technical effects:

[0063] When the commutation failure may occur in the AC system fault, the lower bridge arm circuit of the commutation bridge arm of the main circuit is controlled to conduct reversely and the turn-off circuit of the auxiliary circuit is controlled to conduct to form parallel conduction with the commutation bridge arm, the first fully-controlled valve of the main circuit is controlled to turn off, the current is transferred to the auxiliary circuit, and after the first half-controlled valve of the commutation bridge arm of the main circuit recovers to turn off, the turn-off circuit of the auxiliary circuit is controlled to turn off; the first half-controlled valve of the main circuit adopts a bidirectional switch, and the positive and negative semiconductor devices share a resistance-capacitance circuit and a voltage equalization circuit; six bridge arms share one turn-off circuit, which reduces the number of fully-controlled devices and improves the utilization rate of the arrester, thereby reducing the cost, reducing the complexity and improving the reliability; when operating normally, if the first fully-controlled valve has the ability to continuously turn off the current, the first fully-controlled valve is used to turn off the current, which can improve the power factor and reduce the reactive power loss; since 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, and therefore, the number of thyristor stages in series of the bidirectional half-controlled switch is reduced, thereby improving the efficiency of the converter. BRIEF DESCRIPTION OF DRAWINGS

[0064] Figure 1 is one of the centralized controllable turn-off grid commutation converter schematic diagrams of the embodiments of the application;

[0065] Figure 2is a schematic diagram of a centralized controllably turned-off grid commutated converter of an embodiment of the invention;

[0066] Figure 3 is a schematic diagram of a centralized controllably turned-off grid commutated converter of an embodiment of the invention;

[0067] Figure 4 is a schematic diagram of a centralized controllably turned-off grid commutated converter of an embodiment of the invention;

[0068] Figure 5 is a schematic diagram of a centralized controllably turned-off grid commutated converter of an embodiment of the invention;

[0069] Figure 6 is a schematic diagram of a centralized controllably turned-off grid commutated converter of an embodiment of the invention;

[0070] Figure 7A 、 Figure 7B 、 Figure 7C 、 Figure 7D 、 Figure 7E 、 Figure 7F 、 Figure 7G 、 Figure 7H 、 Figure 7I 、 Figure 7J 、 Figure 7K 、 Figure 7L and Figure 7M are schematic diagrams of valve structures of embodiments of the invention;

[0071] Figure 8 is a circuit diagram of a centralized controllably turned-off grid commutated converter of an embodiment of the invention including a valve structure;

[0072] Figure 9 is a circuit diagram of a centralized controllably turned-off grid commutated converter of an embodiment of the invention including a valve structure;

[0073] Figure 10 is a circuit diagram of a centralized controllably turned-off grid commutated converter of an embodiment of the invention including a valve structure;

[0074] Figure 11 is a circuit diagram of a centralized controllably turned-off grid commutated converter of an embodiment of the invention including a valve structure;

[0075] Figure 12 is a circuit diagram of a centralized controllably turned-off grid commutated converter of an embodiment of the invention including a valve structure;

[0076] Figure 13 is a circuit diagram of a centralized controllably turned-off grid commutated converter of an embodiment of the invention including a valve structure;

[0077] Figure 14This is the seventh circuit diagram of a centralized controllable power grid switching converter with a valve structure in this embodiment of the invention;

[0078] Figure 15 This is the eighth circuit diagram of a centralized controllable power grid phase-switching converter with a valve structure in this embodiment of the invention.

[0079] Figure 16 This is a circuit diagram of a centralized controllable power grid phase-switching converter including a surge arrester, according to an embodiment of the present invention.

[0080] Figure 17 This is a block diagram of the control method for a centralized controllable power grid phase-switching converter according to an embodiment of the present invention;

[0081] Figure 18 This is a schematic diagram of the control method for a centralized controllable power grid phase-switching converter according to an embodiment of the present invention;

[0082] Figure 19 This is a block diagram of the control device for a centralized controllable power grid phase-switching converter according to an embodiment of the present invention;

[0083] Figure 20 This invention relates to a DC transmission system including a centralized controllable power grid switching converter.

[0084] Figure 21A The embodiments of the present invention are based on Figure 8 Simulation diagram of a single-phase ground fault in a valve structure;

[0085] Figure 21B The embodiments of the present invention are based on Figure 8 Simulation diagram of three-phase short-circuit fault in valve structure;

[0086] Figure 22A The embodiments of the present invention are based on Figure 12 Simulation diagram of a single-phase ground fault in a valve structure;

[0087] Figure 22B The embodiments of the present invention are based on Figure 12 Simulation diagram of three-phase short-circuit fault of valve structure.

[0088] Explanation of reference numerals in the attached diagram: 1. Upper bridge arm circuit; 2. Lower bridge arm circuit; 3. Shutdown circuit; 4. First grid phase-commutation converter; 5. Second grid phase-commutation converter; 6. First converter transformer; 7. Second converter transformer; 8. First AC system; 9. DC line; 10. First centralized controllable grid phase-commutation converter; 11. Second centralized controllable grid phase-commutation 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 application will be further described below in conjunction with the accompanying drawings. Figures 1-22B The application will be further described below in conjunction with the accompanying drawings.

[0090] In order to make the objectives, technical solutions and advantages of the embodiments of the application clearer, the technical solutions in the embodiments of the application will be described clearly and completely below in conjunction with the accompanying drawings of the embodiments of the application. Obviously, the described embodiments are only some, but not all of the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the application.

[0091] The embodiment of the application provides a centralized controllable off-grid converter, which comprises a main circuit and an auxiliary circuit, wherein the main circuit comprises at least one upper bridge arm circuit and at least one lower bridge arm circuit, one end of the at least one upper bridge arm circuit is connected with a main circuit anode bus, the other end of the at least one upper bridge arm circuit is connected with one end of the at least one lower bridge arm circuit, and the other end of the at least one lower bridge arm circuit is connected with a main circuit cathode bus; the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each comprise a first half-controlled valve, and the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each comprise a first fully-controlled valve or share one first fully-controlled valve.

[0092] With reference to Figure 1 The main circuit can be a three-phase six-bridge-arm circuit, comprising 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 relationship, and the upper bridge arm circuit 1 and the lower bridge arm circuit 2 of each corresponding relationship correspond to one phase of electricity, one end of each upper bridge arm circuit 1 is connected with the main circuit anode bus, the other end of each upper bridge arm circuit 1 is connected with one end of the corresponding lower bridge arm circuit 2, and the other end of the corresponding lower bridge arm circuit 2 is connected with the main circuit cathode bus; each upper bridge arm circuit 1 and lower bridge arm circuit 2 comprises 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 with the main circuit anode bus, and one end of the first fully-controlled valve of each upper bridge arm circuit 1 is connected with one end of the first fully-controlled valve of the corresponding lower bridge arm circuit 2; the other end of the first half-controlled valve of each lower bridge arm circuit 2 is connected with the main circuit cathode bus.

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

[0094] The A-phase lower bridge arm circuit 2 comprises a first semi-controlled valve V11 and a first fully-controlled valve V12, the first semi-controlled valve V11 and the first fully-controlled valve V12 are connected in series, one end of the first semi-controlled valve V11 is connected with the main circuit cathode bus N1, and one end of the first fully-controlled valve V12 is connected with 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 comprises a first semi-controlled valve V31 and a first fully-controlled valve V32, the first semi-controlled valve V31 and the first fully-controlled valve V32 are connected in series, one end of the first semi-controlled valve V31 is connected with the main circuit cathode bus N1, and one end of the first fully-controlled valve V32 is connected with 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 comprises a first semi-controlled valve V51 and a first fully-controlled valve V52, the first semi-controlled valve V51 and the first fully-controlled valve V52 are connected in series, one end of the first semi-controlled valve V51 is connected with the main circuit cathode bus N1, and one end of the first fully-controlled valve V52 is connected with 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 upper bridge arm circuit is connected with the main circuit anode bus, one end of the first semi-controlled valve of at least one upper bridge arm circuit is connected with one end of the first semi-controlled valve of at least one lower bridge arm circuit; one end of the first fully-controlled valve of at least one lower bridge arm circuit is connected with the main circuit cathode bus, that is, the circuit positions of the first fully-controlled valve and the first semi-controlled valve can be interchanged.

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

[0097] In some embodiments, the first controllable valve has one end connected to the common end of the upper bridge arm circuit and the lower bridge arm circuit of the at least one phase, and the other end of the first controllable valve is an output end; and the first controllable valve has two ends connected in parallel to a fifth semi-controlled valve, and the fifth semi-controlled valve includes at least one of a unidirectional semi-controlled switch and a bidirectional semi-controlled switch.

[0098] The auxiliary circuit includes a shutdown circuit, one end of the shutdown circuit being connected to the anode bus of the main circuit, and the other end of the shutdown circuit being connected to the cathode bus of the main circuit. The shutdown circuit includes a second controllable valve, one end of the second controllable valve being connected to the anode bus of the main circuit, and the other end of the second controllable valve being connected to the cathode bus of the main circuit.

[0099] Referring to Figure 1 , the auxiliary circuit includes a shutdown circuit 3, one end of the shutdown circuit 3 being connected to the anode bus of the main circuit, and the other end of the shutdown circuit 3 being connected to the cathode bus of the main circuit; and the shutdown circuit includes a second controllable valve, one end of the second controllable valve being connected to the anode bus of the main circuit, and the other end of the second controllable valve being connected to the cathode bus of the main circuit.

[0100] In some embodiments, referring to Figure 1 , the shutdown circuit 3 includes a second controllable valve V71, one end of the second controllable valve V71 being connected to the anode bus P1 of the main circuit, and the other end of the second controllable valve V71 being 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 isolation 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 isolation switch and / or a knife switch.

[0102] In some embodiments, the first controllable valve and the second controllable valve each include at least one of a unidirectional controllable switch, a bidirectional controllable switch, and a sub-module series switch, and the first semi-controlled valve includes at least one of a bidirectional semi-controlled switch, an anti-parallel non-controlled switch, and a unidirectional semi-controlled switch.

[0103] In some embodiments, the shutdown circuit further includes a second semi-controlled valve and / or a first non-controlled valve, one end of the second semi-controlled valve and / or the first non-controlled valve being connected to the anode bus of the main circuit, the other end of the second semi-controlled valve and / or the first non-controlled valve being connected to one end of the second controllable valve, and the other end of the second controllable valve being connected to the cathode bus of the main circuit; or, one end of the second semi-controlled valve and / or the first non-controlled valve being connected to the cathode bus of the main circuit, the other end of the second semi-controlled valve and / or the first non-controlled valve being connected to one end of the second controllable valve, and the other end of the second controllable valve being connected to the anode bus of the main circuit.

[0104] Referring to Figure 2The turn-off circuit 3 further comprises 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 with the main circuit anode bus P1, the other end of the second half-controlled valve and / or the first uncontrolled valve V72 is connected with one end of the second fully-controlled valve V71, the other end of the second fully-controlled valve V71 is connected with the main circuit cathode bus N1.

[0105] In some embodiments, the second half-controlled valve comprises a unidirectional half-controlled switch for assisting the second fully-controlled valve to withstand positive and negative voltages, and the first uncontrolled valve comprises an uncontrolled switch for assisting the second fully-controlled valve to withstand negative voltage.

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

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

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

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

[0111] In some embodiments, on the basis that the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each further comprise a second uncontrolled valve, the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each further comprise a third controlled valve and / or a third uncontrolled valve connected in series, and in the case that the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each further comprise a third uncontrolled valve, the third controlled valve and the third uncontrolled valve are connected in series and are connected in anti-parallel with the series circuit of the second uncontrolled valve and the first controlled valve.

[0112] On the basis that the three upper bridge arm circuits 1 and the three lower bridge arm circuits 2 each further comprise a second uncontrolled valve, the three upper bridge arm circuits 1 and the three lower bridge arm circuits 2 each further comprise a third controlled valve and a third uncontrolled valve connected in series, and the third controlled valve and the third uncontrolled valve are connected in anti-parallel with the series circuit of the second uncontrolled valve and the first controlled valve.

[0113] Referring to Figure 4 , the A-phase upper bridge arm circuit 1 further comprises a third controlled valve V44 and a third uncontrolled valve V45 connected in series and connected in anti-parallel with the series circuit of the first controlled valve V42 and the second uncontrolled valve V43; the B-phase upper bridge arm circuit 1 further comprises a third controlled valve V64 and a third uncontrolled valve V65 connected in series and connected in anti-parallel with the series circuit of the first controlled valve V62 and the second uncontrolled valve V63; and the C-phase upper bridge arm circuit 1 further comprises a third controlled valve V24 and a third uncontrolled valve V25 connected in series and connected in anti-parallel with the series circuit of the first controlled valve V22 and the second uncontrolled valve V23.

[0114] The A-phase lower bridge arm circuit 2 further comprises a third controlled valve V14 and a third uncontrolled valve V15 connected in series and connected in anti-parallel with the series circuit of the first controlled valve V12 and the second uncontrolled valve V13; the B-phase lower bridge arm circuit 2 further comprises a third controlled valve V34 and a third uncontrolled valve V35 connected in series and connected in anti-parallel with the series circuit of the first controlled valve V32 and the second uncontrolled valve V33; and the C-phase lower bridge arm circuit 2 further comprises a third controlled valve V54 and a third uncontrolled valve V55 connected in series and connected in anti-parallel with the series circuit of the first controlled valve V52 and the second uncontrolled valve V53.

[0115] In some embodiments, the third controlled valve comprises at least one of a unidirectional controlled switch, a bidirectional controlled switch, and a sub-module series switch; and the third uncontrolled valve comprises an uncontrolled switch.

[0116] In some embodiments, on the basis that the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each comprise the first half-controlled valve and the first fully-controlled valve, the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each further comprise a third half-controlled valve, the third half-controlled valve is connected in parallel with the circuit obtained by connecting the first fully-controlled valve and the second non-controlled valve in series, and in the case that the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each comprise the second non-controlled valve, the third half-controlled valve is connected in parallel with the circuit obtained by connecting the first fully-controlled valve and the second non-controlled valve in series.

[0117] With reference to Figure 5 , the A-phase upper bridge arm circuit 1 further comprises a third half-controlled valve V46 connected in parallel with the circuit obtained by connecting the first fully-controlled valve V42 and the second non-controlled valve V43 in series; the B-phase upper bridge arm circuit 1 further comprises a third half-controlled valve V66 connected in parallel with the circuit obtained by connecting the first fully-controlled valve V62 and the second non-controlled valve V63 in series; and the C-phase upper bridge arm circuit 1 further comprises a third half-controlled valve V26 connected in parallel with the circuit obtained by connecting the first fully-controlled valve V22 and the second non-controlled valve V23 in series.

[0118] The A-phase lower bridge arm circuit 2 further comprises a third half-controlled valve V16 connected in parallel with the circuit obtained by connecting the first fully-controlled valve V12 and the second non-controlled valve V13 in series; the B-phase lower bridge arm circuit 2 further comprises a third half-controlled valve V36 connected in parallel with the circuit obtained by connecting the first fully-controlled valve V32 and the second non-controlled valve V33 in series; and the C-phase lower bridge arm circuit 2 further comprises a third half-controlled valve V56 connected in parallel with the circuit obtained by connecting the first fully-controlled valve V52 and the second non-controlled valve V53 in series. In some embodiments, in the case that the second non-controlled valve is not configured, the third half-controlled valve can be connected in parallel with the first fully-controlled valve, for example, the third half-controlled valve V46 included by the A-phase upper bridge arm circuit 1 is connected in parallel with the first fully-controlled valve V42.

[0119] In some embodiments, the third half-controlled valve comprises at least one of a unidirectional half-controlled switch and a bidirectional half-controlled switch.

[0120] With reference to Figure 6 , on the basis that the three upper bridge arm circuits 1 and the three lower bridge arm circuits 2 each comprise the first half-controlled valve, the first fully-controlled valve, the second non-controlled valve and the third half-controlled valve, the three upper bridge arm circuits 1 and the three lower bridge arm circuits 2 each further comprise a third fully-controlled valve and a third non-controlled valve; the third fully-controlled valve and the third non-controlled valve are connected in series, and are connected in anti-parallel with the circuit obtained by connecting the first fully-controlled valve and the second non-controlled valve in series, and a fourth half-controlled valve is further connected in anti-parallel.

[0121] With reference to Figure 6The upper bridge arm circuit 1 of phase A further comprises a third controllable valve V44 and a third non-controllable valve V45, which are connected in series and are connected in anti-parallel with the circuit in which the first controllable valve V42 and the second non-controllable valve V43 are connected in series, and fourth semi-controllable valves V47 are connected in parallel at both ends of the anti-parallel connection; the upper bridge arm circuit 1 of phase B further comprises a third controllable valve V64 and a third non-controllable valve V65, which are connected in series and are connected in anti-parallel with the circuit in which the first controllable valve V62 and the second non-controllable valve V63 are connected in series, and fourth semi-controllable valves V67 are connected in parallel at both ends of the anti-parallel connection; the upper bridge arm circuit 1 of phase C further comprises a third controllable valve V24 and a third non-controllable valve V25, which are connected in series and are connected in anti-parallel with the circuit in which the first controllable valve V22 and the second non-controllable valve V23 are connected in series, and fourth semi-controllable valves V27 are connected in parallel at both ends of the anti-parallel connection.

[0122] The lower bridge arm circuit 2 of phase A further comprises a third controllable valve V14 and a third non-controllable valve V15, which are connected in series and are connected in anti-parallel with the circuit in which the first controllable valve V12 and the second non-controllable valve V13 are connected in series, and fourth semi-controllable valves V17 are connected in parallel at both ends of the anti-parallel connection; the lower bridge arm circuit 2 of phase B further comprises a third controllable valve V34 and a third non-controllable valve V35, which are connected in series and are connected in anti-parallel with the circuit in which the first controllable valve V32 and the second non-controllable valve V33 are connected in series, and fourth semi-controllable valves V37 are connected in parallel at both ends of the anti-parallel connection; the lower bridge arm circuit 2 of phase C further comprises a third controllable valve V54 and a third non-controllable valve V55, which are connected in series and are connected in anti-parallel with the circuit in which the first controllable valve V52 and the second non-controllable valve V53 are connected in series, and fourth semi-controllable valves V57 are connected in parallel at both ends of the anti-parallel connection.

[0123] In some embodiments, the fourth semi-controllable valve comprises a unidirectional semi-controllable switch.

[0124] In some embodiments, without configuring the third non-controllable valve, the fourth semi-controllable valve is connected in parallel with the third controllable valve.

[0125] In some embodiments, the first controllable valve and the third controllable valve are merged into one controllable valve comprising a bidirectional controllable switch; and / or the third semi-controllable valve and the fourth semi-controllable valve are merged into one semi-controllable valve comprising a bidirectional semi-controllable switch.

[0126] In some embodiments, the first controllable valve, and / or the first semi-controllable valve in the at least one upper bridge arm circuit and the at least one lower bridge arm circuit further comprises a reactor. Optionally, the second semi-controllable valve, and / or the first non-controllable valve, and / or the third semi-controllable valve in the turn-off circuit further comprises a reactor.

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

[0128] In some embodiments, the fully-controlled switch comprises at least one fully-controlled device connected in series, the fully-controlled device comprising at least one of an IGCT (Integrated Gate Commutated Thyristor), an IGBT (Insulated Gate Bipolar Transistor), an inverse-IGCT, a GTO (Gate Turn-Off Thyristor), and a MOSFET (Metal Oxide Semiconductor Field Effect Transistor); the semi-controlled switch comprises at least one semi-controlled device connected in series, the semi-controlled device comprising a thyristor; and the non-controlled switch comprises at least one non-controlled device connected in series, the non-controlled device comprising a diode.

[0129] In some embodiments, with reference to Figure 7A , the non-controlled switch comprises at least one diode connected in series, which cannot control turn-on and turn-off, has a unidirectional current flow capability and a unidirectional blocking voltage capability; with reference to Figure 7B , the unidirectional semi-controlled switch comprises a thyristor connected in series, which only controls turn-on and cannot control turn-off, has a unidirectional current flow capability and a bidirectional blocking voltage capability, and optionally, the unidirectional semi-controlled switch is composed of a thyristor and a diode connected in series; with reference to Figure 7C , the bidirectional semi-controlled switch is composed of a thyristor connected in series in anti-parallel, which only controls turn-on and cannot control turn-off, has a bidirectional current flow capability and a bidirectional blocking voltage capability; with reference to Figure 7D , the anti-parallel unidirectional semi-controlled switch and the non-controlled switch are composed of a thyristor and a diode connected in series in anti-parallel, which only controls turn-on in a unidirectional manner and cannot control turn-off, has a bidirectional current flow capability and a unidirectional blocking voltage capability; with reference to Figure 7E , the unidirectional fully-controlled switch comprises an IGBT module connected in series, the IGBT module comprising an IGBT and a diode connected in anti-parallel therewith, which only controls turn-on and turn-off in a unidirectional manner, has a bidirectional current flow capability and a unidirectional blocking voltage capability; with reference to Figure 7F , the unidirectional fully-controlled switch comprises an inverse-IGCT connected in series, which only controls turn-on and turn-off in a unidirectional manner, has a unidirectional current flow capability and a bidirectional blocking voltage capability; with reference to Figure 7GThe unidirectional fully-controlled switch comprises an IGBT module and a diode connected in series, and is only unidirectionally controlled to turn on and turn off, and has unidirectional current flow and bidirectional blocking voltage capability; refer to Figure 7H The unidirectional fully-controlled switch comprises an inverse blocking type IGCT and a thyristor anti-parallel connected in series, and is bidirectionally controlled to turn on and unidirectionally controlled to turn off, and has bidirectional current flow and bidirectional blocking voltage capability; refer to Figure 7I The bidirectional fully-controlled switch comprises a forward IGBT module and a reverse IGBT module connected in series, and is bidirectionally controlled to turn on and turn off, and has bidirectional current flow and bidirectional blocking voltage capability; refer to Figure 7J The bidirectional fully-controlled switch comprises an inverse blocking type IGCT anti-parallel connected in series, and is bidirectionally controlled to turn on and turn off, and has bidirectional current flow and bidirectional blocking voltage capability; refer to Figure 7K The sub-module series switch comprises half-bridge sub-modules connected in series, each half-bridge sub-module comprising two IGBT modules and a capacitor, the connection point of the two IGBT modules serving as the positive pole of the half-bridge sub-module, and the other end of one of the IGBT modules serving as the negative pole of the half-bridge sub-module, and the half-bridge sub-modules being connected in series, and the half-bridge sub-module series switch being only unidirectionally controlled to turn on and turn off, and having bidirectional current flow and unidirectional blocking voltage capability; refer to Figure 7L The sub-module series switch comprises full-bridge sub-modules connected in series, each full-bridge sub-module comprising four IGBT modules and a capacitor, the IGBT modules being connected in series in pairs and then connected in parallel, and the IGBT modules and the capacitor also being connected in parallel, the connection points of the IGBT modules connected in series in pairs serving as the positive pole and the negative pole of the full-bridge sub-module, respectively, and the full-bridge sub-modules being connected in series, and the full-bridge sub-module series switch being bidirectionally controlled to turn on and turn off, and having bidirectional current flow and bidirectional blocking voltage capability; refer to Figure 7M The sub-module series switch comprises full-bridge sub-modules connected in series, each full-bridge sub-module comprising four IGBT modules and a capacitor, the IGBT modules being connected in series in pairs and then connected in parallel, and the IGBT modules and the capacitor also being connected in parallel, the connection points of the IGBT modules connected in series in pairs serving as the positive pole and the negative pole of the full-bridge sub-module, respectively, and the full-bridge sub-modules being connected in series, and the full-bridge sub-module series switch being bidirectionally controlled to turn on and turn off, and having bidirectional current flow and bidirectional blocking voltage capability; refer to

[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 inverse blocking type IGCT is configured with a corresponding drive circuit and a buffer circuit; the buffer circuit is at least composed of a capacitor; or composed of a resistor and a capacitor series circuit.

[0131] In some embodiments, refer to Figure 8 、 Figure 9 、 Figure 10 、 Figure 11 、 Figure 12 、 Figure 13 、 Figure 14 ,Figure 15 and Figure 16 , the valve structure corresponding to each first fully controlled valve, second fully controlled valve, each third fully controlled valve, each first semi-controlled valve, second semi-controlled valve or first uncontrolled valve, each second uncontrolled valve, each third uncontrolled valve, each third semi-controlled valve and each fourth semi-controlled valve is shown respectively.

[0132] Referring to Figure 8 , in the main circuit, the A-phase upper bridge arm circuit 1 includes the first semi-controlled valve V41 and the first fully controlled valve V42 connected in series, the B-phase upper bridge arm circuit 1 includes the first semi-controlled valve V61 and the first fully controlled valve V62 connected in series, the C-phase upper bridge arm circuit 1 includes the first semi-controlled valve V21 and the first fully controlled valve V22 connected in series, the A-phase lower bridge arm circuit 2 includes the first semi-controlled valve V11 and the first fully controlled valve V12 connected in series, the B-phase lower bridge arm circuit 2 includes the first semi-controlled valve V31 and the first fully controlled valve V32 connected in series, and the C-phase lower bridge arm circuit 2 includes the first semi-controlled valve V51 and the first fully controlled valve V52 connected in series. Each first semi-controlled valve adopts the bidirectional semi-controlled switch shown in Figure 7C , which is composed of thyristors connected in series in anti-parallel, and the thyristors can share a buffer circuit and a voltage equalization circuit; and each first fully controlled valve adopts the unidirectional fully controlled switch shown in Figure 7E , which is composed of IGBT modules connected in series; alternatively, if each first fully controlled valve adopts the sub-module series switch shown in Figure 7K , Figure 7L or Figure 7M , during commutation, the additional commutation voltage is provided by the turn-off of the first fully controlled valve, and the forced turn-off current will reduce the reactive loss of the centralized controllable turn-off grid commutated converter.

[0133] In the auxiliary circuit, the turn-off circuit 3 includes the second fully controlled valve V71, which adopts the unidirectional fully controlled switch shown in Figure 7E , which 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 connections are required; at the same time, since the IGBT module includes a diode connected in anti-parallel, the converter does not have reverse DC voltage operating capability.

[0134] Referring to Figure 9 , the valve structure is different from that of Figure 8 , in which the first fully controlled valve adopts the unidirectional fully controlled switch shown in Figure 7H , which is composed of an inverse resistance type IGCT and a thyristor connected in anti-parallel and then connected in series.

[0135] Referring to Figure 10 , the valve structure is different from that of Figure 8 , in which the turn-off circuit further includes the second semi-controlled valve V72. The second semi-controlled valve V72 adopts the bidirectional semi-controlled switch shown in Figure 7BThe unidirectional half-controlled switch shown is composed of thyristors connected 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 of the second fully-controlled valve V71 can be reduced; at the same time, since the thyristor of the second half-controlled valve V72 can bear the reverse DC voltage, the converter has the reverse DC voltage operating capability.

[0136] With reference to Figure 11 , unlike the valve structure of Figure 8 , the A, B, C three-phase upper bridge arm circuit and the A, B, C three-phase lower bridge arm circuit further respectively include a second uncontrolled valve.

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

[0138] With reference to Figure 12 , unlike the valve structure of Figure 8 , the A, B, C three-phase upper bridge arm circuit 1 and the A, B, C three-phase lower bridge arm circuit 2 further respectively include a third fully-controlled valve and a third uncontrolled valve.

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

[0140] Referring to Figure 13 , the valve structure of Figure 8 , the A-phase, B-phase and C-phase upper bridge arm circuits and the A-phase, B-phase and C-phase lower bridge arm circuits further comprise a second non-controlled valve and a third semi-controlled valve respectively.

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

[0142] Reference Figure 14 ,and Figure 13 Unlike other valves, the shut-off circuit also includes a second semi-controlled valve, V72. The second semi-controlled valve V72 employs... Figure 7B The unidirectional semi-controlled switch shown is composed of thyristors connected in series.

[0143] Reference Figure 15 ,and Figure 12 The valve structure is different from that of the three-phase upper bridge arm circuit (A, B, C) and the three-phase lower bridge arm circuit (A, B, C), which also include a third half-control valve and a fourth half-control valve respectively.

[0144] In the main circuit, the A-phase upper bridge arm circuit 1 comprises a first semi-controlled valve V41, a first fully-controlled valve V42, a second non-controlled valve V43, a third fully-controlled valve V44, a third non-controlled valve V45, a third semi-controlled valve V46 and a fourth semi-controlled valve V47; the first fully-controlled valve V42 and the second non-controlled valve V43 are connected in series, the third fully-controlled valve V44 and the third non-controlled valve V45 are connected in series, and the third semi-controlled valve V46 and the fourth semi-controlled valve V47 are connected in parallel; the B-phase upper bridge arm circuit 1 comprises a first semi-controlled valve V61, a first fully-controlled valve V62, a second non-controlled valve V63, a third fully-controlled valve V64, a third non-controlled valve V65, a third semi-controlled valve V66 and a fourth semi-controlled valve V67; the first fully-controlled valve V62 and the second non-controlled valve V63 are connected in series, the third fully-controlled valve V64 and the third non-controlled valve V65 are connected in series, and the third semi-controlled valve V66 and the fourth semi-controlled valve V67 are connected in parallel; the C-phase upper bridge arm circuit 1 comprises a first semi-controlled valve V21, a first fully-controlled valve V22, a second non-controlled valve V23, a third fully-controlled valve V24, a third non-controlled valve V25, a third semi-controlled valve V26 and a fourth semi-controlled valve V27; the first fully-controlled valve V22 and the second non-controlled valve V23 are connected in series, the third fully-controlled valve V24 and the third non-controlled valve V25 are connected in series, and the third semi-controlled valve V26 and the fourth semi-controlled valve V27 are connected in parallel; the A-phase lower bridge arm circuit 2 comprises a first semi-controlled valve V11, a first fully-controlled valve V12, a second non-controlled valve V13, a third fully-controlled valve V14, a third non-controlled valve V15, a third semi-controlled valve V16 and a fourth semi-controlled valve V17; the first fully-controlled valve V12 and the second non-controlled valve V13 are connected in series, the third fully-controlled valve V14 and the third non-controlled valve V15 are connected in series, and the third semi-controlled valve V16 and the fourth semi-controlled valve V17 are connected in parallel; the B-phase lower bridge arm circuit 2 comprises a first semi-controlled valve V31, a first fully-controlled valve V32, a second non-controlled valve V33, a third fully-controlled valve V34, a third non-controlled valve V35, a third semi-controlled valve V36 and a fourth semi-controlled valve V37; the first fully-controlled valve V32 and the second non-controlled valve V33 are connected in series, the third fully-controlled valve V34 and the third non-controlled valve V35 are connected in series, and the third semi-controlled valve V36 and the fourth semi-controlled valve V37 are connected in parallel; the C-phase lower bridge arm circuit 2 comprises a first semi-controlled valve V51, a first fully-controlled valve V52, a second non-controlled valve V53, a third fully-controlled valve V54, a third non-controlled valve V55, a third semi-controlled valve V56 and a fourth semi-controlled valve V57; the first fully-controlled valve V52 and the second non-controlled valve V53 are connected in series, the third fully-controlled valve V54 and the third non-controlled valve V55 are connected in series, and the third semi-controlled valve V56 and the fourth semi-controlled valve V57 are connected in parallel; the third semi-controlled valve and the fourth semi-controlled valve described above are single-direction semi-controlled switches composed of thyristors connected in series, or the third semi-controlled valve and the fourth semi-controlled valve are merged into bidirectional semi-controlled switches as shown. Figure 7B Figure 7C

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

[0146] In some embodiments, with reference to Figure 16 , on the basis of Figure 14 , each first controllable valve, second controllable valve, each first semi-controllable valve and each second non-controllable valve are connected in parallel with a surge arrester, for example, the first semi-controllable valve V41 of the upper bridge arm circuit 1 of phase A is connected in parallel with a surge arrester F41, the first controllable valve V42 is connected in parallel with a surge arrester F42, and the second non-controllable valve V43 is connected in parallel with a surge arrester F43; the first semi-controllable valve V11 of the lower bridge arm circuit 2 of phase A is connected in parallel with a surge arrester F11, the first controllable valve V12 is connected in parallel with a surge arrester F12, and the second non-controllable valve V13 is connected in parallel with a surge arrester F13; the first semi-controllable valve V61 of the upper bridge arm circuit 1 of phase B is connected in parallel with a surge arrester F61, the first controllable valve V62 is connected in parallel with a surge arrester F62, and the second non-controllable valve V63 is connected in parallel with a surge arrester F63; the first semi-controllable valve 31 of the lower bridge arm circuit 2 of phase B is connected in parallel with a surge arrester F31, the first controllable valve V32 is connected in parallel with a surge arrester F32, and the second non-controllable valve V33 is connected in parallel with a surge arrester F33; the first semi-controllable valve V21 of the upper bridge arm circuit 1 of phase C is connected in parallel with a surge arrester F21, the first controllable valve V22 is connected in parallel with a surge arrester F22, and the second non-controllable valve V23 is connected in parallel with a surge arrester F23; the first semi-controllable valve 51 of the lower bridge arm circuit 2 of phase C is connected in parallel with a surge arrester F51, the first controllable valve V52 is connected in parallel with a surge arrester F52, and the second non-controllable valve V53 is connected in parallel with a surge arrester F53; the second controllable valve V71 of the shutdown circuit 3 is connected in parallel with a surge arrester F71, and the second semi-controllable valve V72 is connected in parallel with a surge arrester F72.

[0147] The application provides a centralized controllable shutdown power grid commutation 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 a physical controller, the server can be a physical server, a server cluster composed of multiple physical servers or a distributed system, or a cloud server providing cloud computing services. The terminal device can be a smart phone, a tablet computer, a notebook computer, a desktop computer or the like, but is not limited thereto. The control device, the server and the terminal device can be directly or indirectly connected through wired or wireless communication, and the embodiments of the application do not make specific limitations.

[0148] With reference to Figure 17 , the centralized controllable shutdown power grid commutation converter control method comprises steps S101, S102 and S103, wherein

[0149] S101, in the case where the operating parameter information of the centralized controllable shutdown power grid commutation converter is acquired, generating 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.

[0150] In some embodiments, the electronic device monitors the operating state of the centralized controllable turn-off grid commutation converter in real time, and obtains operating parameter information of the operating state of the centralized controllable turn-off grid commutation converter, such as alternating current voltage, direct current, etc. In the case where the electronic device obtains the operating state of the centralized controllable turn-off grid commutation converter, the electronic device generates inverter state control information, such as a trigger pulse, and the centralized controllable turn-off grid commutation 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 time points are controlled to be turned on at the same time. For example, in a certain time period within an alternating current 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 a six-pulse inverter working mode.

[0151] In the case where the first fully-controlled valve is composed of a sub-module series switch, and a parallel lightning arrester or a parallel absorption circuit is provided to make the first fully-controlled valve have a continuous turn-off current capability, an additional commutation voltage is provided by the first fully-controlled valve during commutation to force the turn-off current, thereby reducing the turn-off angle and reducing the reactive power loss of the centralized controllable turn-off grid commutation converter. For example, the first fully-controlled valve is composed of a half-bridge sub-module series as shown in FIG. 1, and during commutation of the A-phase upper bridge arm circuit and the B-phase upper bridge arm, the A-phase voltage is lower than the B-phase voltage. The first fully-controlled valve V42 is controlled to be turned off, the half-bridge sub-module of the first fully-controlled valve V42 is charged and an additional commutation voltage is provided, so that the A-phase voltage is higher than the B-phase voltage, and the current is forced to change from the A-phase to the B-phase. Then the first half-controlled valve V41 is controlled to be reversely turned on to release the electric quantity of the capacitor in the half-bridge sub-module. Figure 7K

[0152] S102, in the case where the commutation fault information is obtained, a first turn-on instruction and a first turn-off instruction are generated, and another bridge arm circuit of the same phase of the commutation bridge arm is controlled to be reversely turned on and the turn-off circuit of the auxiliary circuit is controlled to be turned on based on the first turn-on instruction; the first fully-controlled valve of the commutation bridge arm is controlled to be turned off based on the first turn-off instruction.

[0153] In some embodiments, the commutation fault information includes fault information causing the commutation bridge arm of the main circuit to fail in natural commutation. The above-mentioned commutation fault information includes an alternating current system fault or a direct current system fault connected to the centralized controllable turn-off grid commutation converter. The alternating current system fault can be judged according to an increase in alternating current voltage zero sequence component, an alternating current voltage mutation, an alternating current voltage amplitude drop, an increase in alternating current voltage harmonic, and an increase in direct current. The direct current system fault can be judged according to a direct current voltage drop and an increase in direct current, but is not limited thereto.

[0154] ​In some embodiments, the natural commutation failure is a commutation failure that occurs when the commutation is only dependent on the commutation voltage provided by the AC system. Whether the natural commutation failure occurs can be determined according to the turn-off time of the second and third half-controlled valves, the AC current at the grid side or the valve side, and the AC voltage. If the second and third half-controlled valves of the commutation bridge arm have not been turned off at the time when they start to bear positive voltage under normal AC voltage, it is determined that the natural commutation failure occurs, but this is not limiting.

[0155] The electronic device generates the first turn-on instruction and the first turn-off instruction when the commutation failure information is obtained, and then controls another bridge circuit of the same phase of the commutation bridge arm to conduct reversely and controls the turn-off circuit of the auxiliary circuit to conduct based on the first turn-on instruction, and controls the first fully-controlled valve of the commutation bridge arm to turn off based on the first turn-off instruction. For example, when the A-phase upper bridge circuit and the B-phase upper bridge circuit are commutated, the A-phase upper bridge circuit is the commutation bridge arm, the B-phase upper bridge circuit is the bridge arm to be commutated, and the commutation failure information is obtained, the A-phase lower bridge circuit is controlled to conduct reversely and the turn-off circuit is controlled to conduct, and the first fully-controlled valve of the A-phase upper bridge 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 circuit and the turn-off circuit.

[0156] In the case where the commutation margin is insufficient, the commutation bridge arm of the main circuit may fail to commutate naturally, for example, when the A-phase upper bridge circuit and the B-phase upper bridge circuit are commutated, the A-phase voltage is lower than the B-phase voltage during commutation, and the commutation cannot be performed normally depending on the AC voltage. At this time, the A-phase upper bridge arm of the main circuit may fail to commutate naturally.

[0157] S103, generating a second turn-off instruction when the first half-controlled valve of the commutation bridge arm of the main circuit recovers turn-off, and controlling the turn-off circuit of the auxiliary circuit to turn off.

[0158] In some embodiments, when the electronic device detects that the first half-controlled valve of the commutation bridge arm of the main circuit recovers turn-off, a second turn-off instruction is generated, and the centralized controllable turn-off grid commutation converter responds to the second turn-off instruction to control the turn-off circuit corresponding to the commutation bridge arm to turn off, so that the current is transferred from the phase where the commutation bridge arm is located to the phase to be commutated, effectively inhibiting the occurrence of commutation failure. For example, when the electronic device detects that the first half-controlled valve of the A-phase upper bridge circuit of the main circuit recovers turn-off, a second turn-off instruction is generated, and the centralized controllable turn-off grid commutation converter responds to the second turn-off instruction to control the turn-off circuit to turn off, so as to provide sufficient commutation voltage to transfer the current from the A-phase upper bridge circuit to the B-phase upper bridge circuit.

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

[0160] In some embodiments, in the case of overvoltage or failure of the second fully-controlled valve, the upper bridge arm circuit and the lower bridge arm circuit of one phase electric 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, in the case of overvoltage or failure of the first fully-controlled valve, a third semi-controlled valve is connected in parallel across the first fully-controlled valve, or a third semi-controlled valve is connected in parallel across the first fully-controlled valve and the second non-controlled valve connected in series, and the third semi-controlled valve is controlled to be turned on.

[0162] In some embodiments, in the case of failure of the turn-off circuit of the auxiliary circuit, the disconnecting switch and / or the knife switch are separated, and the anode bus of the main circuit is connected to the cathode bus of the main circuit through the disconnecting switch and / or the knife switch.

[0163] In some embodiments, in the case of overvoltage or failure of the third fully-controlled valve, a fourth semi-controlled valve is connected in parallel across the third fully-controlled valve, or a fourth semi-controlled valve is connected in parallel across the third fully-controlled valve and the third non-controlled valve connected in series, and the fourth semi-controlled valve is controlled to be turned on.

[0164] In some embodiments, in the case of turn-off of the turn-off circuit of the auxiliary circuit, the third fully-controlled valve is controlled to be turned off, and the upper bridge arm circuit and the lower bridge arm circuit of at least one phase each further include the third fully-controlled valve.

[0165] In some embodiments, according to the control method described above, the first fully-controlled valve needs to have a rated current or an overload current current-carrying capacity, but in the case of failure of the DC power transmission system, the first fully-controlled valve only needs to provide a small turn-off voltage to divert the fault current to another bridge arm circuit of the same phase of the turn-off circuit and the phase-changing bridge arm. The second fully-controlled valve only functions when the phase-changing failure information is obtained, and needs to provide a short-time overcurrent capacity and a large turn-off voltage to turn off the fault current and provide a phase-changing voltage. In the case of turn-off of the second fully-controlled valve, the current is diverted to the parallel-connected surge arrester, and the surge arrester provides the turn-off voltage and absorbs the energy. The turn-off circuit and the surge arrester of the present application are configured in a centralized manner, and no matter whether it is an asymmetric alternating current fault or a symmetric alternating current fault, the same surge arrester is used for absorption, thereby improving the utilization rate of the surge arrester and enhancing the ability to resist phase-changing failure.

[0166] According to some embodiments, in the case that the semiconductor device in the bidirectional semiconductor switch of the first half-controlled valve of the centralized controllable turn-off grid commutated converter bears a forward or reverse voltage exceeding a limit value, the bidirectional semiconductor switch is controlled to be forward or reverse turned on.

[0167] In some embodiments, with reference to Figure 8 For example, when the A-phase upper bridge arm circuit of the main circuit commutates to the B-phase upper bridge arm circuit, in the case that the commutation fault information is obtained, the first half-controlled valve V11 of the A-phase lower bridge arm circuit is controlled to be reverse turned on, the second fully-controlled valve V71 of the turn-off circuit of the auxiliary circuit is controlled to be turned on, and the first fully-controlled valve V42 of the A-phase upper bridge arm circuit of the main 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 turn-off circuit of the auxiliary circuit.

[0168] In some embodiments, with reference to Figure 9 For example, when the A-phase upper bridge arm circuit of the main circuit commutates to the B-phase upper bridge arm circuit, in the case that the commutation fault information is obtained, the first half-controlled valve V11 and the first fully-controlled valve V12 of the A-phase lower bridge arm circuit are controlled to be reverse turned on, the second fully-controlled valve V71 of the turn-off circuit of the auxiliary circuit is controlled to be turned on, and the first fully-controlled valve V42 of the A-phase upper bridge arm circuit of the main 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 turn-off circuit of the auxiliary circuit.

[0169] In some embodiments, with reference to Figure 10 For example, when the A-phase upper bridge arm circuit of the main circuit commutates to the B-phase upper bridge arm circuit, in the case that the commutation fault information is obtained, the first half-controlled valve V11 of the A-phase lower bridge arm circuit is controlled to be reverse turned on, the second fully-controlled valve V71 and the second half-controlled valve V72 of the turn-off circuit of the auxiliary circuit are controlled to be turned on, and the first fully-controlled valve V42 of the A-phase upper bridge arm circuit of the main 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 turn-off circuit of the auxiliary circuit.

[0170] In some embodiments, with reference to Figure 11For example, in the case of phase A upper bridge arm circuit to phase B upper bridge arm circuit commutation, if the commutation fault information is obtained, the first half-controlled valve V11 and the second uncontrolled valve V13 of the phase A lower bridge arm circuit are controlled to reverse conduction, and the second fully-controlled valve V71 of the shutdown circuit of the auxiliary circuit is controlled to conduct; the first fully-controlled valve V42 of the phase A upper bridge arm circuit is controlled to shut down, so that the current of the phase A upper bridge arm circuit is transferred to the phase A lower bridge arm circuit and the shutdown circuit of the auxiliary circuit; after the first half-controlled valve V41 of the phase A upper bridge arm circuit of the main circuit recovers to shut down, the second fully-controlled valve V71 of the shutdown circuit of the auxiliary circuit is controlled to shut down, so that the current is transferred from the phase A upper bridge arm circuit to the phase B upper bridge arm circuit.

[0171] In some embodiments, with reference to Figure 12 For example, in the case of phase A upper bridge arm circuit to phase B upper bridge arm circuit commutation, if the commutation fault information is obtained, the first half-controlled valve V11 and the second uncontrolled valve V13 of the phase A lower bridge arm circuit are controlled to reverse conduction, and the second fully-controlled valve V71 of the shutdown circuit of the auxiliary circuit is controlled to conduct; the first fully-controlled valve V42 of the phase A upper bridge arm circuit is controlled to shut down, so that the current of the phase A upper bridge arm circuit is transferred to the phase A lower bridge arm circuit and the shutdown circuit of the auxiliary circuit; after the first half-controlled valve V41 of the phase A upper bridge arm circuit of the main circuit recovers to shut down, the second fully-controlled valve V71 of the shutdown circuit of the auxiliary circuit is controlled to shut down, so that the current is transferred from the phase A upper bridge arm circuit to the phase B upper bridge arm circuit.

[0172] In some embodiments, with reference to Figure 13 For example, in the case of phase A upper bridge arm circuit to phase B upper bridge arm circuit commutation, if the commutation fault information is obtained, the first half-controlled valve V11 and the second uncontrolled valve V13 of the phase A lower bridge arm circuit are controlled to reverse conduction, and the second fully-controlled valve V71 of the shutdown circuit of the auxiliary circuit is controlled to conduct; the first fully-controlled valve V42 of the phase A upper bridge arm circuit is controlled to shut down, so that the current of the phase A upper bridge arm circuit is transferred to the phase A lower bridge arm circuit and the shutdown circuit of the auxiliary circuit; after the first half-controlled valve V41 of the phase A upper bridge arm circuit of the main circuit recovers to shut down, the second fully-controlled valve V71 of the shutdown circuit of the auxiliary circuit is controlled to shut down, so that the current is transferred from the phase A upper bridge arm circuit to the phase B upper bridge arm circuit.

[0173] In some embodiments, with reference to Figure 14 and Figure 16For example, when the A-phase upper bridge arm circuit switches to the B-phase upper bridge arm circuit, if the commutation 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 fully-controlled valve V71 and the second half-controlled valve V72 of the auxiliary circuit are controlled to be conducted; the first fully-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 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 turned off, the second fully-controlled valve V71 of the auxiliary circuit is controlled to be turned off, 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 that the first fully-controlled valve V42 is overvoltage or fails, the third half-controlled valve V46 is controlled to be forwardly conducted and replace the first fully-controlled valve V42 to work.

[0174] In some embodiments, referring to Figure 15 For example, when the A-phase upper bridge arm circuit switches to the B-phase upper bridge arm circuit, if the commutation 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 fully-controlled valve V71 and the second half-controlled valve V72 of the auxiliary circuit are controlled to be conducted; the first fully-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 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 turned off, the second fully-controlled valve V71 and the third fully-controlled valve V14 of the auxiliary circuit are controlled to be turned off, 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 that the first fully-controlled valve V42 is overvoltage or fails, the third half-controlled valve V46 is controlled to be forwardly conducted and replace the first fully-controlled valve V42 to work; in the case that the third fully-controlled valve V14 is overvoltage or fails, the fourth half-controlled valve V17 is controlled to be conducted and replace the third fully-controlled valve V14 to work.

[0175] The above control of the first half-controlled valve, the second half-controlled valve, the third half-controlled valve, the fourth half-controlled valve, the first fully-controlled valve, the second fully-controlled valve and the third fully-controlled valve is realized by applying a trigger pulse, and the valves are in the conducting state when they bear the forward voltage at the same time. The above control of the first half-controlled valve in the reverse direction is realized by applying a trigger pulse to the reverse thyristor, and the valve is in the reverse conducting state when it bears the reverse voltage at the same time.

[0176] In some embodiments, referring to Figure 18 For example, when the A-phase upper bridge arm circuit switches to the B-phase upper bridge arm circuit, if the commutation 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 fully-controlled valve V71 and the second half-controlled valve V72 of the auxiliary circuit are controlled to be conducted; the first fully-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 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 turned off, the second fully-controlled valve V71 and the third fully-controlled valve V14 of the auxiliary circuit are controlled to be turned off, 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 that the first fully-controlled valve V42 is overvoltage or fails, the third half-controlled valve V46 is controlled to be forwardly conducted and replace the first fully-controlled valve V42 to work; in the case that the third fully-controlled valve V14 is overvoltage or fails, the fourth half-controlled valve V17 is controlled to be conducted and replace the third fully-controlled valve V14 to work. Figure 17The control method provided in the application is used as a basis to provide a centralized controllable turn-off grid commutation converter control method flow chart, wherein first, the main circuit is controlled to operate in inverter mode, then it is judged whether the commutation bridge arm fails to commutate naturally, in the case that the commutation bridge arm is judged not to fail to commutate naturally, the main circuit is continuously controlled to operate in inverter mode, in the case that the commutation bridge arm is judged to fail to commutate naturally, the other bridge arm of the phase where the commutation bridge arm is located is controlled to conduct reversely, the turn-off circuit of the auxiliary circuit is controlled to conduct, and the first fully-controlled valve of the commutation bridge arm is controlled to turn off, then, after the commutation bridge arm is restored to turn off, the turn-off circuit of the auxiliary circuit is controlled to turn off.

[0177] Referring to Figure 19 The centralized controllable turn-off grid commutation converter control device 20 can 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 operating parameter information of the centralized controllable turn-off grid commutation converter is acquired, and control the main circuit to operate in inverter state based on the inverter state control information;

[0179] The second control module 202 is used to generate a first conduction instruction and a first turn-off instruction when the commutation fault information is acquired, and control the other bridge circuit of the same phase of the commutation bridge arm to conduct reversely and control the turn-off circuit of the auxiliary circuit to conduct based on the first conduction instruction; control the first fully-controlled valve of the commutation bridge arm to turn off based on the first turn-off instruction;

[0180] The third control module 203 is used to generate a second turn-off instruction when the first half-controlled valve of the commutation bridge arm of the main circuit is restored to turn off, and control the turn-off circuit of the auxiliary circuit to turn off.

[0181] In some embodiments, the first control module 201 can contain a logic circuit, or be realized by a central processor, a microprocessor, a digital signal processor or a field programmable gate array contained by a device, etc.

[0182] The second control module 202 can contain a logic circuit, or be realized by a central processor, a microprocessor, a digital signal processor or a field programmable gate array contained by a device, etc.

[0183] The third control module 203 can contain a logic circuit, or be realized by a central processor, a microprocessor, a digital signal processor or a field programmable gate array contained by a device, etc.

[0184] The embodiment of the application provides a high-voltage direct-current power transmission system, which includes a centralized controllable turn-off grid commutation converter.

[0185] In some embodiments, the high-voltage direct current power transmission system is a two-terminal direct current power transmission system or a multi-terminal direct current power transmission system, which respectively comprises a single-pole direct current power transmission system, a bipolar direct current power transmission system or a back-to-back direct current system.

[0186] In some embodiments, part or all of the invert-operated converters of the two-terminal direct current power transmission system or the multi-terminal direct current power transmission system adopt the above-mentioned centralized controllably blocked grid-commutated converters.

[0187] Referring to Figure 20 , Figure 20 A structure of one pole of a bipolar direct current power transmission system is shown, which comprises 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 controllably blocked grid-commutated converter 10, a second centralized controllably blocked grid-commutated converter 11, a third converter transformer 12 and a fourth converter transformer 13. In the case of positive power sending, alternating current of the first alternating current system 8 is rectified into direct current by the first grid-commutated converter 4 and the second grid-commutated converter 5 after passing through the first converter transformer 6 and the second converter transformer 7, is transmitted to the first centralized controllably blocked grid-commutated converter 10 and the second centralized controllably blocked grid-commutated converter 11 through the direct current line 9, and is inverted into alternating current, which is transmitted to the second alternating current system 14 after passing through the third converter transformer 12 and the fourth converter transformer 13, thereby realizing the transmission of direct current power. The first centralized controllably blocked grid-commutated converter 10 and the second centralized controllably blocked grid-commutated converter 11 have the ability to suppress commutation failure, thereby ensuring the reliability of direct current power transmission.

[0188] Referring to Figure 21A , Figure 21A A structure of one pole of a bipolar direct current power transmission system is shown, which comprises 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 controllably blocked grid-commutated converter 10, a second centralized controllably blocked grid-commutated converter 11, a third converter transformer 12 and a fourth converter transformer 13. In the case of positive power sending, alternating current of the first alternating current system 8 is rectified into direct current by the first grid-commutated converter 4 and the second grid-commutated converter 5 after passing through the first converter transformer 6 and the second converter transformer 7, is transmitted to the first centralized controllably blocked grid-commutated converter 10 and the second centralized controllably blocked grid-commutated converter 11 through the direct current line 9, and is inverted into alternating current, which is transmitted to the second alternating current system 14 after passing through the third converter transformer 12 and the fourth converter transformer 13, thereby realizing the transmission of direct current power. The first centralized controllably blocked grid-commutated converter 10 and the second centralized controllably blocked grid-commutated converter 11 have the ability to suppress commutation failure, thereby ensuring the reliability of direct current power transmission. Figure 20 Figure 8 ​The valve structure is shown. UAC_IN_L1, UAC_IN_L2 and UAC_IN_L3 are three-phase alternating voltages; IVY_L1_SCA, IVY_L2_SCA and IVY_L3_SCA are three-phase valve-side alternating currents; UDL_IN is a direct voltage; IDNC_IN is a direct current; MAIN_BRANCH_CP1, MAIN_BRANCH_CP2, MAIN_BRANCH_CP3, MAIN_BRANCH_CP4, MAIN_BRANCH_CP5 and MAIN_BRANCH_CP6 are trigger pulses of forward semiconductor devices of bidirectional half-controlled switches of first half-controlled valves V11, V21, V31, V41, V51 and V61 respectively, the turn-on time of first fully-controlled valves V12, V22, V32, V42, V52 and V62 is the same as the trigger pulse of the first half-controlled valve, and the turn-off time is delayed on the basis of 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 trigger pulses of reverse semiconductor devices of bidirectional half-controlled switches of first half-controlled valves V11, V21, V31, V41, V51 and V61 respectively, and the six signals are phase or trigger pulses of a second fully-controlled valve V71. After an A-phase ground fault occurs in the alternating current system, the alternating voltage UAC_IN_L1 becomes 0, when it is detected that the first half-controlled valve V11, V21, V31, V41, V51 or V61 may fail to commutate, the corresponding V41, V51, V61, V11, V21 or V31 is controlled to conduct reversely, the second fully-controlled valve V71 is controlled to conduct, the corresponding first fully-controlled valve V12, V22, V32, V42, V52 or V62 is controlled to turn 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 restores to turn off, the second fully-controlled valve V71 is controlled to turn off. During the entire fault period, the valve-side alternating currents IVY_L1_SCA, IVY_L2_SCA and IVY_L3_SCA can still successfully commutate, the direct voltage UDL_IN is maintained at about 50%, and the direct current IDNC_IN can also be maintained at the pre-fault level fluctuation. Test results show that the topology structure can realize self-commutation, maintain a certain power transmission and will not fail to commutate when a single-phase alternating current fault occurs. Referring to Figure 21B , Figure 21B It is shown that Figure 20 the three-phase short-circuit fault test results of the second alternating current system 14 of the high-voltage direct current transmission system, wherein the first centralized controllable blocking grid commutation converter 10 and the second centralized controllable blocking grid commutation converter 11 adoptFigure 8 The valve structure is shown. After the three-phase short-circuit fault of the alternating current system, the alternating voltages UAC_IN_L1, UAC_IN_L2 and UAC_IN_L3 are all 0, and the valve-side alternating currents IVY_L1_SCA, IVY_L2_SCA and IVY_L3_SCA can still be commutated successfully during the entire fault period, self-commutation without alternating voltage during the fault is achieved, and a controlled short-circuit current can be provided. After the second fully controlled valve V71 is turned off, due to the fact that the alternating 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 freewheeling current.

[0189] Referring to Figure 22A , Figure 22A It is shown that Figure 20 The single-phase ground fault test results of the second alternating current system 14 of the high-voltage direct current power transmission system are shown, wherein the first centralized controllable blocking grid commutation converter 10 and the second centralized controllable blocking grid commutation converter 11 adopt Figure 12The valve structure is shown. UAC_IN_L1, UAC_IN_L2 and UAC_IN_L3 are three-phase alternating voltages; IVY_L1_SCA, IVY_L2_SCA and IVY_L3_SCA are three-phase valve-side alternating currents; UDL_IN is a direct voltage; IDNC_IN is a direct current; MAIN_BRANCH_CP1, MAIN_BRANCH_CP2, MAIN_BRANCH_CP3, MAIN_BRANCH_CP4, MAIN_BRANCH_CP5 and MAIN_BRANCH_CP6 are trigger pulses of forward semiconductor devices of bidirectional half-controlled switches of first half-controlled valves V11, V21, V31, V41, V51 and V61 respectively, the turn-on time of first fully-controlled valves V12, V22, V32, V42, V52 and V62 is the same as the trigger pulse of the first half-controlled valve, and the turn-off time is delayed on the basis of 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 trigger pulses of reverse semiconductor devices of bidirectional half-controlled switches of first half-controlled valves V11, V21, V31, V41, V51 and V61 respectively, and are also trigger pulses of third fully-controlled valves V14, V24, V34, V44, V54 and V64 respectively; the six signals are phase or trigger pulses of second fully-controlled valve V71. After an A-phase ground fault occurs in the alternating current system, the alternating voltage UAC_IN_L1 becomes 0, when it is detected that the first half-controlled valve V11, V21, V31, V41, V51 or V61 may fail to commutate, the corresponding V41, V51, V61, V11, V21 or V31 is controlled to conduct reversely, the V44, V54, V64, V14, V24 or V34 is controlled to conduct, the second fully-controlled valve V71 is controlled to conduct, the corresponding first fully-controlled valve V12, V22, V32, V42, V52 or V62 is controlled to turn 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 turns off, the second fully-controlled valve V71 is controlled to turn off. During the entire fault period, the valve-side alternating currents IVY_L1_SCA, IVY_L2_SCA and IVY_L3_SCA can still successfully commutate, the direct voltage UDL_IN is maintained at about 50%, and the direct current IDNC_IN can also be maintained at the pre-fault level fluctuation. Test results show that the topology structure can realize self-commutation, maintain a certain power transmission and will not fail to commutate when a single-phase alternating current fault occurs. Referring to Figure 22B , Figure 22B It is shown that Figure 20The test results of the three-phase short-circuit fault of the second AC system 14 of the shown HVDC system, wherein the first centralized controllable blocking grid commutated converter 10 and the second centralized controllable blocking grid commutated converter 11 are used Figure 12 The valve structure is shown. After the three-phase short-circuit fault of the AC system, the AC voltages UAC_IN_L1, UAC_IN_L2 and UAC_IN_L3 are all 0, and the valve-side AC currents IVY_L1_SCA, IVY_L2_SCA and IVY_L3_SCA can still commutate successfully during the entire fault period, self-commutation without the AC voltage during the fault is achieved, and a controlled short-circuit current can be provided. After the second fully-controlled valve V71 is blocked, the third fully-controlled valve is also blocked, and there is no freewheeling current.

[0190] The above is only some embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A centralized controllable turn-off line-commutated converter, characterized in that The application relates to a main circuit and an auxiliary circuit. The main circuit comprises at least one upper bridge arm circuit and at least one lower bridge arm circuit, one end of the at least one upper bridge arm circuit is connected with a main circuit anode bus, the other end of the at least one upper bridge arm circuit is connected with one end of the at least one lower bridge arm circuit, and the other end of the at least one lower bridge arm circuit is connected with a main circuit cathode bus; the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each comprise a first half-controlled valve, and the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each comprise a first full-controlled valve or share one first full-controlled valve. The auxiliary circuit comprises a shutdown circuit, one end of the shutdown circuit is connected with the main circuit anode bus, and the other end of the shutdown circuit is connected with the main circuit cathode bus.

2. The concentrated controllable commutated pole converter of claim 1, wherein, The shutdown circuit comprises a second full-controlled valve. One end of the second full-controlled valve is connected with the main circuit anode bus, and the other end of the second full-controlled valve is connected with the main circuit cathode bus. The second full-controlled valve comprises at least one of a unidirectional full-controlled switch, a bidirectional full-controlled switch and a sub-module series switch.

3. The concentrated controllable commutated pole converter of claim 2, wherein, The shutdown circuit further comprises a second half-controlled valve and / or a first non-controlled valve. The second half-controlled valve and / or the first non-controlled valve are connected in series with the second full-controlled valve. The second half-controlled valve comprises a unidirectional half-controlled switch, and the first non-controlled valve comprises a non-controlled switch.

4. The concentrated controllable commutated converter of claim 3, wherein, The second full-controlled valve is connected in parallel with a lightning arrester, and / or the second half-controlled valve and / or the first non-controlled valve are connected in parallel with a lightning arrester.

5. The concentrated controllable commutation grid converter of claim 1, wherein, The first half-controlled valve comprises at least one of a bidirectional half-controlled switch, a non-controlled switch in anti-parallel connection and a unidirectional half-controlled switch; and the first full-controlled valve comprises at least one of a unidirectional full-controlled switch, a bidirectional full-controlled switch and a sub-module series switch.

6. The concentrated controllable commutated converter of claim 5, wherein, The bidirectional half-controlled switch is composed of controllable turn-on but uncontrollable turn-off semiconductor devices in anti-parallel connection and series connection, and the controllable turn-on but uncontrollable turn-off semiconductor devices include but are not limited to thyristors. The unidirectional half-controlled switch is composed of controllable turn-on but uncontrollable turn-off semiconductor devices in series connection, and the controllable turn-on but uncontrollable turn-off semiconductor devices include but are not limited to thyristors. The non-controlled switch is composed of non-controlled turn-on and turn-off semiconductor devices in series connection, and the non-controlled turn-on and turn-off semiconductor devices include but are not limited to diodes. The unidirectional full-controlled switch is composed of semiconductor devices with unidirectional turn-off capability in series connection, and the semiconductor devices with unidirectional turn-off capability include but are not limited to insulated gate bipolar transistors, integrated gate-commutated thyristors and reverse blocking integrated gate-commutated thyristors. The bidirectional full-controlled switch is composed of semiconductor devices with bidirectional turn-off capability in series connection, and the semiconductor devices with bidirectional turn-off capability include but are not limited to reverse blocking integrated gate-commutated thyristors in anti-parallel connection and insulated gate bipolar transistors in reverse series connection. The sub-module series switch is composed of sub-modules in series connection, and the sub-modules include but are not limited to half-bridge sub-modules, full-bridge sub-modules, full-bridge-like sub-modules and clamped double sub-modules; and the semiconductor devices of the half-bridge sub-modules, the full-bridge sub-modules, the full-bridge-like sub-modules and the clamped double sub-modules include but are not limited to insulated gate bipolar transistors and integrated gate-commutated thyristors.

7. The concentrated controllable commutation grid converter of claim 1, wherein, In the case that the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each comprise a first fully-controlled valve, the first semi-controlled valve and the first fully-controlled valve are connected in series.

8. The concentrated controllable commutated converter of claim 7, wherein, One end of the first semi-controlled valve of the at least one upper bridge arm circuit is connected with the main circuit anode bus, and one end of the first fully-controlled valve of the at least one upper bridge arm circuit is connected with one end of the first fully-controlled valve of the at least one lower bridge arm circuit; one end of the first semi-controlled valve of the at least one lower bridge arm circuit is connected with the main circuit cathode bus. Or, One end of the first fully-controlled valve of the at least one upper bridge arm circuit is connected with the main circuit anode bus, one end of the first semi-controlled valve of the at least one upper bridge arm circuit is connected with one end of the first semi-controlled valve of the at least one lower bridge arm circuit; one end of the first fully-controlled valve of the at least one lower bridge arm circuit is connected with the main circuit cathode bus.

9. The concentrated controllable commutated converter of claim 7, wherein, The at least one upper bridge arm circuit and the at least one lower bridge arm circuit each further comprise a second non-controlled valve, the second non-controlled valve is connected in series with the first fully-controlled valve; the second non-controlled valve comprises any one of a non-controlled switch, a non-controlled switch in anti-parallel connection and a unidirectional semi-controlled switch.

10. The concentrated controllable commutated converter of claim 7, wherein, The first semi-controlled valve is connected in parallel with a lightning arrester and / or the first fully-controlled valve is connected in parallel with a lightning arrester.

11. A concentrated controllable turn-off line commutated converter according to claim 7, characterised in that, Both ends of the first fully-controlled valve are connected in parallel with a third semi-controlled valve; or, In the case that the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each further comprise a second non-controlled valve, both ends of the first fully-controlled valve and the second non-controlled valve connected in series are connected in parallel with a third semi-controlled valve. The third semi-controlled valve comprises at least one of a unidirectional semi-controlled switch and a bidirectional semi-controlled switch.

12. The concentrated controllable commutation grid converter of claim 9, wherein, The at least one upper bridge arm circuit and the at least one lower bridge arm circuit each further comprise a third fully-controlled valve and / or a third non-controlled valve; in the case that the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each further comprise a third non-controlled valve, the third fully-controlled valve and the third non-controlled valve are connected in series, and are connected in anti-parallel connection with a series circuit composed of the second non-controlled valve and the first fully-controlled valve; The third fully-controlled valve comprises at least one of a unidirectional fully-controlled switch, a bidirectional fully-controlled switch and a sub-module series switch; the third non-controlled valve comprises a non-controlled switch.

13. The concentrated controllable commutated converter of claim 12, wherein, Both ends of the third fully-controlled valve are connected in parallel with a fourth semi-controlled valve; or, In the case that the at least one upper bridge arm circuit and the at least one lower bridge arm circuit each further comprise a third non-controlled valve, both ends of the third fully-controlled valve and the third non-controlled valve connected in series are connected in parallel with a fourth semi-controlled valve; the fourth semi-controlled valve comprises a unidirectional semi-controlled switch.

14. The concentrated controllable commutation grid converter of claim 1, wherein, The first fully-controlled valve of the at least one upper bridge arm circuit and the first fully-controlled valve of the at least one lower bridge arm circuit are connected in parallel with an absorption circuit.

15. The concentrated controllable commutation grid converter of claim 1, wherein, The shutdown circuit of the auxiliary circuit and the main circuit anode bus are connected through a disconnecting switch and / or a knife switch, and the main circuit cathode bus is connected through a disconnecting switch and / or a knife switch.

16. The concentrated controllable commutation grid converter of claim 1, wherein, The first fully-controlled valve and / or the first semi-controlled valve further comprise an electric reactor.

17. A concentrated controllable commutated converter according to any one of the preceding claims, wherein the converter is a concentrated controllable commutated converter (CCCC) of the line commutated converter (LCC) type. In the case that the first full-controlled valve is shared by the at least one upper bridge arm circuit and the at least one lower bridge arm circuit, one end of the first full-controlled valve is connected to the common end of the at least one upper bridge arm circuit and the at least one lower bridge arm circuit, and the other end of the first full-controlled valve is an output end.

18. The concentrated controllable commutation grid converter of claim 17, wherein, The fifth half-controlled valve is connected in parallel across the first full-controlled valve, and the fifth half-controlled valve comprises at least one of a unidirectional half-controlled switch and a bidirectional half-controlled switch.

19. The concentrated controllable commutated converter of any of claims 12, wherein, The first full-controlled valve and the third full-controlled valve are combined as a full-controlled valve comprising a bidirectional full-controlled switch; and / or, The third half-controlled valve connected in parallel across the first full-controlled valve and the fourth half-controlled valve connected in parallel across the third full-controlled valve are combined as a half-controlled valve comprising a bidirectional half-controlled switch.

20. A method of controlling a concentrated controllable turn-off line commutated converter, characterized by A method for controlling the centralized controllably turned-off grid commutated converter according to any one of claims 1-19, comprising: In the case that the operating parameter information of the centralized controllably turned-off grid commutated converter is obtained, 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; In the case that the commutation fault information is obtained, generating a first turn-on instruction and a first turn-off instruction, and controlling the other bridge arm circuit of the same phase of the commutation bridge arm of the main circuit to be reversely turned on and controlling the turn-off circuit of the auxiliary circuit to be turned on based on the first turn-on instruction; and controlling the first full-controlled valve of the commutation bridge arm to be turned off based on the first turn-off instruction; In the case that the first half-controlled valve of the commutation bridge arm of the main circuit is recovered to be turned off, generating a second turn-off instruction, and controlling the turn-off circuit of the auxiliary circuit to be turned off.

21. The method of claim 20, wherein, In the case that the first full-controlled valve is composed of a sub-module series switch, or is connected in parallel with a lightning arrester, or is connected in parallel with an absorption circuit, additional commutation voltage is provided by the first full-controlled valve during commutation in normal operation.

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

23. The method of claim 20, wherein, In the case that the second full-controlled valve is overvoltage or fails, the upper bridge arm circuit and the lower bridge arm circuit of one phase of current are controlled to be turned on at the same time.

24. The method of claim 20, wherein, In the case that the first full-controlled valve is connected in parallel with a third half-controlled valve, or the first full-controlled valve and a second non-controlled valve are connected in series and then connected in parallel with a third half-controlled valve, and the first full-controlled valve is overvoltage or fails, the third half-controlled valve is controlled to be turned on.

25. The method of claim 20, wherein, In the case that the turn-off circuit of the auxiliary circuit and the anode bus of the main circuit are connected through disconnectors and / or knife switches, and the cathode bus of the main circuit is connected through disconnectors and / or knife switches, and the turn-off circuit fails, the disconnectors and / or knife switches are separated.

26. The method of claim 20, wherein, In the case that a semiconductor device of a bidirectional half-controlled switch of the first half-controlled valve of the centralized controllably turned-off grid commutated converter bears a positive or negative voltage exceeding a limit value, the bidirectional half-controlled switch is controlled to be positively or negatively turned on.

27. The method of any one of claims 20-26, wherein, In the case that the third full-controlled valve is connected in parallel with a fourth half-controlled valve, or the third full-controlled valve and a third non-controlled valve are connected in series and then connected in parallel with a fourth half-controlled valve, and the third full-controlled valve is overvoltage or fails, the fourth half-controlled valve is controlled to be turned on.

28. The method of claim 27, wherein, The at least one upper bridge arm circuit and the at least one lower bridge arm circuit each further comprise a third controllable valve, and the third controllable valve is controlled to be turned off in the case that the turn-off circuit of the auxiliary circuit is turned off.

29. A centralized controllable turn-off line-commutated-converter control device, characterized by A method for controlling the centralized controllable turn-off grid commutated converter according to any one of claims 1-19, comprising: a first control module configured to, in the case that operating parameter information of the centralized controllable turn-off grid commutated converter is obtained, generate inverter state control information based on the parameter information, and control the main circuit to operate in an inverter state based on the inverter state control information; a second control module configured to, in the case that commutation fault information is obtained, generate a first turn-on instruction and a first turn-off instruction, and control another bridge arm circuit of the same phase of the commutation bridge arm of the main circuit to be reversely turned on and control the turn-off circuit of the auxiliary circuit to be turned on based on the first turn-on instruction; and control the first controllable valve of the commutation bridge arm to be turned off based on the first turn-off instruction; a third control module configured to, in the case that the first semiconductor valve of the commutation bridge arm of the main circuit is turned off, generate a second turn-off instruction, and control the turn-off circuit of the auxiliary circuit to be turned off.

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

31. The system of claim 30, wherein, 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 comprises a single-pole direct current transmission system, a bipolar direct current transmission system or a back-to-back direct current system.

32. The system of claim 31, wherein, Some or all of the inverters required to operate in an inverter mode in the two-terminal direct current transmission system or the multi-terminal direct current transmission system adopt the centralized controllable turn-off grid commutated converter.

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