A hybrid converter topology structure with DC side auxiliary commutation and control method thereof

Abstract

The present invention relates to a hybrid converter topology structure with auxiliary commutation on the DC side and a control method thereof, comprising: a three-phase six-bridge-arm circuit and an auxiliary commutation circuit connected in parallel with the DC side of the three-phase six-bridge-arm circuit and having forward current controllable shutdown and forward and reverse voltage blocking capabilities; the auxiliary commutation circuit is respectively connected to the connection points of the upper bridge arm and the lower bridge arm of each phase bridge arm circuit in the three-phase six-bridge-arm circuit through a two-way valve with two-way opening and two-way pressure resistance capabilities on each phase AC bus in the three-phase AC bus; the present invention can solve the commutation fault problem of the hybrid converter topology structure by adding an auxiliary commutation circuit connected in parallel with the DC side of the three-phase six-bridge-arm circuit in the hybrid converter topology structure, and the technical solution is simple to implement and low in cost.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a hybrid converter topology structure with auxiliary commutation on a DC side and a control method thereof. Background Art

[0002] The traditional line commutated converter high voltage direct current (LCC-HVDC) transmission system has the advantages of long-distance large-capacity transmission and controllable active power, and is widely used around the world. However, since the thyristors used in its converter need to rely on the AC system to provide commutation voltage, commutation failure is prone to occur in the event of AC system failure, resulting in a surge in DC current and a rapid and large loss of DC transmission power. In addition, in recent years, some regional power grids have multiple DC feeds. Once a commutation failure occurs in a DC line, it may cause a chain commutation failure of multiple DC lines through AC system coupling, bringing more severe challenges to the safe and stable operation of the power grid.

[0003] In view of the problem of commutation failure in traditional DC transmission, many scholars have done a lot of research and invented a variety of converter topologies with the function of resisting commutation failure. For example, one is the capacitor commutation converter topology (CCC), which increases the valve commutation voltage time area through the capacitor voltage to ensure its reliable shutdown; based on the basic principle of the capacitor commutation circuit, a variety of topologies have evolved, and the controllable capacitor module is formed by combining power electronic switches and capacitors to realize the controllable capacitor input and voltage direction; but the above-mentioned topology based on capacitor commutation is difficult to implement. Another is to form a hybrid converter by connecting the turn-off device and the thyristor in series, so that each bridge arm of the converter has the ability to be turned off, avoiding the occurrence of commutation failure; due to the large transmission capacity of conventional DC transmission, each bridge arm of the converter is subjected to high voltage and high current. In this topology, the turn-off valve must be realized by multi-stage series-parallel connection. At the same time, the turn-off valve can withstand high current for a long time and withstand high voltage stress when the high current is turned off, which requires more series connection. Therefore, the cost and difficulty of engineering implementation of this technical solution are both high. In addition, the prior art also uses a turn-off device to forcibly turn off the current to achieve current transfer. However, this commutation technology increases operating losses due to the long-term conduction of current by the turn-off device, and requires the installation of cooling equipment, making the cost of implementing this technical solution relatively high. Summary of the invention

[0004] In view of the deficiencies in the prior art, the object of the present invention is to provide a hybrid converter topology structure with auxiliary commutation on the DC side and a control method thereof. By adding an auxiliary commutation circuit in parallel with the DC side of the three-phase six-bridge arm circuit in the hybrid converter topology structure, the commutation failure problem of the hybrid converter topology structure is solved. The technical solution is simple to implement and low-cost.

[0005] The purpose of the present invention is achieved by adopting the following technical solutions:

[0006] The present invention provides a hybrid converter topology structure with auxiliary commutation on the DC side, the improvement of which lies in that the topology structure comprises: a three-phase six-bridge arm circuit and an auxiliary commutation circuit with forward current controllable shutdown and forward and reverse voltage blocking capabilities connected in parallel with the DC side of the three-phase six-bridge arm circuit;

[0007] The auxiliary commutation circuit is connected to the connection points of the upper bridge arm and the lower bridge arm of each phase bridge arm circuit in the three-phase six-bridge arm circuit through a two-way valve with two-way opening and two-way pressure resistance capabilities on each phase AC bus in the three-phase AC bus.

[0008] Preferably, the upper bridge arm and the lower bridge arm of each phase bridge arm circuit in the three-phase six-bridge arm circuit are composed of a thyristor valve connected in series and a turnable valve with forward current controllable turnoff and forward voltage blocking capabilities.

[0009] Further, the auxiliary commutation circuit is composed of an upper bridge arm auxiliary valve and a lower bridge arm auxiliary valve connected in series;

[0010] The connection point between the upper bridge arm auxiliary valve and the lower bridge arm auxiliary valve is respectively connected to the connection point between the upper bridge arm and the lower bridge arm of each phase bridge arm circuit in the three-phase six-bridge arm circuit through the two-way valve on each phase AC bus in the three-phase AC bus.

[0011] Furthermore, the auxiliary commutation circuit is a three-phase six-bridge arm structure;

[0012] Each phase bridge arm structure in the three-phase six-bridge arm structure is composed of an upper bridge arm auxiliary valve and a lower bridge arm auxiliary valve connected in series;

[0013] The connection points between the upper bridge arm auxiliary valve and the lower bridge arm auxiliary valve of each phase bridge arm structure in the three-phase six-bridge arm structure are respectively connected to the connection points of the upper bridge arm and the lower bridge arm of each phase bridge arm circuit in the three-phase six-bridge arm circuit through the two-way valves on each phase AC bus in the three-phase AC bus.

[0014] Furthermore, the thyristor valve is composed of a plurality of thyristors and a buffer component connected in series or in parallel with each of the plurality of thyristors.

[0015] Furthermore, the shutoff valve, the upper bridge arm auxiliary valve and the lower bridge arm auxiliary valve are each composed of a plurality of auxiliary submodules connected in series and a buffer component connected in series or in parallel with each of the plurality of auxiliary submodules connected in series;

[0016] The auxiliary submodule is composed of one or more fully-controlled power electronic devices with reverse voltage blocking capability, or is composed of a fully-controlled power electronic device without reverse voltage blocking capability, a diode connected in reverse parallel to the fully-controlled power electronic device without reverse voltage blocking capability, and a buffer component connected in series or in parallel with the fully-controlled power electronic device without reverse voltage blocking capability.

[0017] Furthermore, the shut-off valve, the upper bridge arm auxiliary valve and the lower bridge arm auxiliary valve are all composed of a first auxiliary branch, a buffer component and a second auxiliary branch connected in parallel;

[0018] The first auxiliary branch and the second auxiliary branch are both composed of two groups of auxiliary timing control branches connected in forward series;

[0019] The auxiliary timing control circuit is composed of a plurality of auxiliary submodules connected in series and a buffer component connected in series or in parallel with each of the plurality of auxiliary submodules connected in series;

[0020] The auxiliary submodule is composed of one or more fully controlled power electronic devices with reverse voltage blocking capability, or is composed of a fully controlled power electronic device without reverse voltage blocking capability, a diode connected in reverse parallel to the fully controlled power electronic device without reverse voltage blocking capability, and a buffer component connected in series or in parallel to the fully controlled power electronic device without reverse voltage blocking capability;

[0021] The external connection point of the first auxiliary branch and the external connection point of the second auxiliary branch are respectively the connection points of the two groups of auxiliary timing control branches of the first auxiliary branch and the connection points of the two groups of auxiliary timing control branches of the second auxiliary branch.

[0022] Furthermore, the shut-off valve, the upper bridge arm auxiliary valve and the lower bridge arm auxiliary valve are all composed of a first diode branch, an auxiliary branch and a second diode branch connected in parallel;

[0023] The first diode branch and the second diode branch are both composed of two groups of diode timing control branches connected in forward series;

[0024] The auxiliary branch is composed of a plurality of auxiliary submodules connected in series and a buffer component connected in series or in parallel with each of the plurality of auxiliary submodules connected in series;

[0025] The auxiliary submodule is composed of one or more fully controlled power electronic devices with reverse voltage blocking capability, or is composed of a fully controlled power electronic device without reverse voltage blocking capability, a diode connected in reverse parallel to the fully controlled power electronic device without reverse voltage blocking capability, and a buffer component connected in series or in parallel to the fully controlled power electronic device without reverse voltage blocking capability;

[0026] The external connection point of the first diode branch and the external connection point of the second diode branch are respectively connection points of two groups of diode timing control branches of the first diode branch and the second diode branch.

[0027] Furthermore, the shut-off valve, the upper bridge arm auxiliary valve and the lower bridge arm auxiliary valve are all composed of a third auxiliary branch and a fourth auxiliary branch connected in reverse parallel with the third auxiliary branch;

[0028] The third auxiliary branch is composed of a plurality of auxiliary submodules connected in series and a buffer component connected in series or in parallel with each of the plurality of auxiliary submodules connected in series;

[0029] The fourth auxiliary branch is composed of a capacitor connected in series, a plurality of auxiliary submodules connected in series, and a buffer component connected in series or in parallel with each of the plurality of auxiliary submodules connected in series;

[0030] The auxiliary submodule is composed of one or more fully-controlled power electronic devices with reverse voltage blocking capability, or is composed of a fully-controlled power electronic device without reverse voltage blocking capability, a diode connected in reverse parallel to the fully-controlled power electronic device without reverse voltage blocking capability, and a buffer component connected in series or in parallel with the fully-controlled power electronic device without reverse voltage blocking capability.

[0031] Preferably, the bidirectional valve is composed of a first thyristor branch and a second thyristor branch connected in reverse parallel thereto;

[0032] The first thyristor branch and the second thyristor branch are both composed of a plurality of thyristor modules connected in series in the forward direction;

[0033] The thyristor module consists of a thyristor and a buffer component connected in series or in parallel with the thyristor.

[0034] Preferably, the two-way valve is composed of a first two-way valve branch and a second two-way valve branch connected in reverse parallel with the first two-way valve branch;

[0035] The first two-way valve branch and the second two-way valve branch are both composed of a first two-way valve timing control branch and a second two-way valve timing control branch connected in reverse series with the first two-way valve timing control branch;

[0036] The first two-way valve timing control branch and the second two-way valve timing control branch are both composed of a plurality of auxiliary submodules connected in series and buffer components connected in series or in parallel with each of the auxiliary submodules in the plurality of auxiliary submodules connected in series;

[0037] The auxiliary submodule is composed of one or more fully-controlled power electronic devices with reverse voltage blocking capability, or is composed of a fully-controlled power electronic device without reverse voltage blocking capability, a diode connected in reverse parallel to the fully-controlled power electronic device without reverse voltage blocking capability, and a buffer component connected in series or in parallel with the fully-controlled power electronic device without reverse voltage blocking capability.

[0038] Preferably, the two-way valve is composed of a third two-way valve branch, an auxiliary branch and a fourth two-way valve branch connected in parallel;

[0039] The third two-way valve branch and the fourth two-way valve branch are both composed of two two-way valve timing control branches connected in series in a forward direction;

[0040] The two bidirectional valve timing control circuits are each composed of a plurality of diodes connected in forward series and buffer components connected in series or in parallel with the plurality of diodes connected in forward series;

[0041] The auxiliary branch is composed of a plurality of auxiliary submodules connected in series and a buffer component connected in series or in parallel with each of the plurality of auxiliary submodules connected in series;

[0042] The auxiliary submodule is composed of one or more fully controlled power electronic devices with reverse voltage blocking capability, or is composed of a fully controlled power electronic device without reverse voltage blocking capability, a diode connected in reverse parallel to the fully controlled power electronic device without reverse voltage blocking capability, and a buffer component connected in series or in parallel to the fully controlled power electronic device without reverse voltage blocking capability;

[0043] The external connection point of the third two-way valve branch and the external connection point of the fourth two-way valve branch are respectively the connection point of the two diode timing control branches of the third two-way valve branch and the connection point of the two diode timing control branches of the fourth two-way valve branch.

[0044] Furthermore, the buffer component is composed of one or more types of capacitors, resistor-capacitor circuits, diodes, inductors or lightning arresters connected in series or in parallel.

[0045] Based on the same inventive concept, the present invention also provides a control method for a hybrid converter topology structure with auxiliary commutation on the DC side, the improvement of which is that the method comprises:

[0046] Turning on the shutoff valve of the i-th bridge arm in the hybrid converter topology structure, shutting off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, and performing the following steps;

[0047] Step 11. Turn on the thyristor valve of the i-th bridge arm in the hybrid converter topology structure, and execute step 12;

[0048] Step 12. After a control cycle T, return to step 11;

[0049] Among them, i∈[1,6].

[0050] Preferably, when t f When a commutation failure or short circuit fault is detected in the i-th bridge arm of the hybrid converter topology, at t f The bidirectional valve connected to the i-th bridge arm in the hybrid converter topology is turned on at time t f The auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology is turned on at time t f At time +Δt1, the turn-off valve of the i-th bridge arm in the hybrid converter topology is turned off, and when the thyristor valve of the i-th bridge arm in the hybrid converter topology is in the forward blocking state and the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology is forced to be turned off, the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology is turned off. When t f At the end of the control cycle, step S11 is executed, until the voltage of the hybrid converter topology structure returns to stability, the switchable valve of the i-th bridge arm in the hybrid converter topology structure is turned on, the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure is turned off, and step 11 is executed;

[0051] Step S11. Turn on the thyristor valve of the i-th bridge arm in the hybrid converter topology, turn on the switchable valve of the i-th bridge arm in the hybrid converter topology, and turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology. Then, execute step S12;

[0052] Step S12 turns on the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure, turns on the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, and The turnable valve of the i-th bridge arm in the hybrid converter topology structure is turned off at all times. When the thyristor valve of the i-th bridge arm in the hybrid converter topology structure is in a forward blocking state and the bidirectional valve connected to the i-th bridge arm is forced to be turned off, step S13 is executed;

[0053] Step S13: Turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, after Δt′ off Then, return to step S11;

[0054] Among them, Δt′ off The duration during which the thyristor valve of the i-th bridge arm in the hybrid converter topology is in the forward blocking state within a control cycle of executing steps S11 to S13, Δt1 is the delay duration for shutting down the switchable valve of the i-th bridge arm in the hybrid converter topology, and T is a control cycle.

[0055] Based on the same inventive concept, the present invention also provides a control method for a hybrid converter topology structure, the improvement of which is that the method comprises:

[0056] Step S21. Turn on the thyristor valve of the i-th bridge arm in the hybrid converter topology, turn on the switchable valve of the i-th bridge arm in the hybrid converter topology, and turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology. Then, execute step S22;

[0057] Step S22. Turn on the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure, turn on the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, The switchable valve of the i-th bridge arm in the hybrid converter topology is turned off at all times. When the thyristor valve of the i-th bridge arm in the hybrid converter topology is in a forward blocking state and the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology is forced to be turned off, step S23 is executed;

[0058] Step S23: Turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, after ΔT' off Then, return to step S21;

[0059] Where i∈[1,6], ΔT' off is the time duration that the thyristor valve of the i-th bridge arm in the hybrid converter topology is in the forward blocking state within one control cycle, Δt1 is the delay time for shutting off the switchable valve of the i-th bridge arm in the hybrid converter topology, and T is one control cycle.

[0060] Based on the same inventive concept, the present invention also provides a control method for a hybrid converter topology structure, the improvement of which is that the method comprises:

[0061] Turning on the shutoff valve of the i-th bridge arm in the hybrid converter topology, shutting off the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology, shutting off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology, and performing the following steps;

[0062] Step 21. Turn on the thyristor valve of the i-th bridge arm in the hybrid converter topology structure, and execute step 22;

[0063] Step 22. After a control cycle T, return to step 21;

[0064] Among them, i∈[1,6].

[0065] Preferably, when t f When a commutation failure or short circuit fault is detected in the i-th bridge arm of the hybrid converter topology, at t f The bidirectional valve connected to the i-th bridge arm in the hybrid converter topology is turned on at time t f The auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology is turned on at time t f At time +Δt1, the turnable valve of the i-th bridge arm in the hybrid converter topology is turned off, and when the thyristor valve of the i-th bridge arm in the hybrid converter topology is in the forward blocking state, the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology is turned off, and the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology is turned off. When t f At the end of the control cycle, step T11 is executed until the voltage of the hybrid converter topology structure returns to stability, the switchable valve of the i-th bridge arm in the hybrid converter topology structure is turned on, the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure is turned off, the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure is turned off, and step 21 is executed;

[0066] Step T11. Turn on the thyristor valve of the i-th bridge arm in the hybrid converter topology, turn on the switchable valve of the i-th bridge arm in the hybrid converter topology, turn off the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology, turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology, and then Then, execute step T12;

[0067] Step T12. Turn on the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure, turn on the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, Turning off the turnable valve of the i-th bridge arm in the hybrid converter topology structure at all times, when the thyristor valve of the i-th bridge arm in the hybrid converter topology structure is in a forward blocking state, executing step T13;

[0068] Step T13. Turn off the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure, turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, and after Δt" off Then, return to step T11;

[0069] Where, Δt” off The time duration during which the thyristor valve of the i-th bridge arm in the hybrid converter topology is in the forward blocking state within a control cycle of executing step T11 to step T13, Δt1 is the delay time for shutting down the switchable valve of the i-th bridge arm in the hybrid converter topology, and T is a control cycle.

[0070] Based on the same inventive concept, the present invention also provides a control method for a hybrid converter topology structure, wherein the method comprises:

[0071] Step T21. Turn on the thyristor valve of the i-th bridge arm in the hybrid converter topology, turn on the switchable valve of the i-th bridge arm in the hybrid converter topology, turn off the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology, turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology, and then Then, execute step T22;

[0072] Step T22. Turn on the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure, turn on the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, Turning off the turnable valve of the i-th bridge arm in the hybrid converter topology structure at all times, when the thyristor valve of the i-th bridge arm in the hybrid converter topology structure is in a forward blocking state, executing step T23;

[0073] Step T23. Turn off the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure, turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, and after ΔT' off Then, return to step T21;

[0074] Where i∈[1,6], ΔT' off is the time duration that the thyristor valve of the i-th bridge arm in the hybrid converter topology is in the forward blocking state within one control cycle, Δt1 is the delay time for shutting off the switchable valve of the i-th bridge arm in the hybrid converter topology, and T is one control cycle.

[0075] Compared with the closest prior art, the present invention has the following beneficial effects:

[0076] The present invention relates to a hybrid converter topology structure with auxiliary commutation on the DC side and a control method thereof, comprising: a three-phase six-bridge arm circuit and an auxiliary commutation circuit connected in parallel with the DC side of the three-phase six-bridge arm circuit and having the capability of controllable shutdown of forward current and blocking forward and reverse voltages; the auxiliary commutation circuit is respectively connected to the connection points of the upper bridge arm and the lower bridge arm of each phase bridge arm circuit in the three-phase six-bridge arm circuit through a two-way valve on each phase AC bus in the three-phase AC bus; the present invention can transfer the commutation current and flexibly control the commutation time when the converter commutation fails by adding an auxiliary commutation circuit, and utilizes the large current shutdown characteristics of the switchable device to quickly restore the commutation between the two bridge arms, thereby greatly speeding up the commutation after the commutation failure. The invention reduces the recovery time of the thyristor; the shut-off valve introduced into the main bridge arm of the invention shuts down in case of a fault, making the main bridge arm current zero, and provides a reverse voltage at the same time, thereby increasing the thyristor valve switching time area to ensure its reliable shutdown. The voltage stress is mainly borne by the thyristor valve, and the number of series stages is small, so the device loss is low; the bidirectional valve of the invention provides a transfer path for the main bridge arm current to switch to the auxiliary switching circuit in case of a fault, and by controlling the opening direction of the bidirectional valve, the upper and lower bridge arms of each phase are respectively switched to the auxiliary switching circuit; when the hybrid converter topology structure of the invention adopts an alternating operation control method, the occurrence of short-circuit current and switching failure can be avoided, thereby improving the overall reliability of the converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 is a schematic diagram of a topological structure of a hybrid converter provided by a first embodiment of the present invention;

[0078] Figure 2 is a schematic diagram of a topological structure of a hybrid converter provided by a second embodiment of the present invention;

[0079] Figure 3 Schematic diagram of the structure of the shutoff valve and the auxiliary valve of the hybrid converter topology structure provided by the first embodiment and the second embodiment of the present invention;

[0080] Figure 4 Schematic diagram of a bidirectional valve structure of a hybrid converter topology structure provided by the first embodiment and the second embodiment of the present invention;

[0081] Figure 5 is a schematic structural diagram of a buffer component of a hybrid converter topology structure provided by the first embodiment and the second embodiment of the present invention;

[0082] Figure 6 is a first control timing diagram of the hybrid converter topology structure provided by the first embodiment and the second embodiment of the present invention;

[0083] Figure 7 is a second control timing diagram of the hybrid converter topology structure provided by the first embodiment and the second embodiment of the present invention;

[0084] Figure 8 This is the current flow path when the hybrid converter topology structure provided by the first embodiment and the second embodiment of the present invention fails. DETAILED DESCRIPTION

[0085] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0086] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0087] The present invention provides a hybrid converter topology structure with auxiliary commutation on the DC side, the topology structure comprising: a three-phase six-bridge arm circuit and an auxiliary commutation circuit with forward current controllable shutdown and forward and reverse voltage blocking capabilities connected in parallel with the DC side of the three-phase six-bridge arm circuit;

[0088] The auxiliary commutation circuit is connected to the connection points of the upper bridge arm and the lower bridge arm of each phase bridge arm circuit in the three-phase six-bridge arm circuit through a two-way valve with two-way opening and two-way pressure resistance capabilities on each phase AC bus in the three-phase AC bus.

[0089] Figure 1 In the figure, Vg1~Vg6 are shut-off valves, DVa, DVb, DVc are two-way valves, and Vp and Vq are auxiliary valves.

[0090] Figure 2 Among them, Vg1~Vg6 are shut-off valves, DVa, DVb, DVc are two-way valves, and Vpa, Vqa, Vpb, Vqb, Vpc, Vq are auxiliary valves.

[0091] like Figure 1 and Figure 2 As shown, the upper bridge arm and the lower bridge arm of each phase bridge arm circuit in the above three-phase six-bridge arm circuit are composed of a thyristor valve connected in series and a turnable valve with forward current controllable turn-off and forward voltage blocking capabilities.

[0092] In the first embodiment provided by the present invention, Figure 1 As shown, the auxiliary commutation circuit is composed of an upper bridge arm auxiliary valve and a lower bridge arm auxiliary valve connected in series;

[0093] The connection point between the upper bridge arm auxiliary valve and the lower bridge arm auxiliary valve is respectively connected to the connection point between the upper bridge arm and the lower bridge arm of each phase bridge arm circuit in the three-phase six-bridge arm circuit through the two-way valve on each phase AC bus in the three-phase AC bus.

[0094] In the second embodiment provided by the present invention, Figure 2 As shown, the auxiliary commutation circuit is a three-phase six-bridge arm structure;

[0095] Each phase bridge arm structure in the three-phase six-bridge arm structure is composed of an upper bridge arm auxiliary valve and a lower bridge arm auxiliary valve connected in series;

[0096] The connection points between the upper bridge arm auxiliary valve and the lower bridge arm auxiliary valve of each phase bridge arm structure in the three-phase six-bridge arm structure are respectively connected to the connection points of the upper bridge arm and the lower bridge arm of each phase bridge arm circuit in the three-phase six-bridge arm circuit through the two-way valves on each phase AC bus in the three-phase AC bus.

[0097] Furthermore, the thyristor valve is composed of a plurality of thyristors and a buffer component connected in series or in parallel with each of the plurality of thyristors.

[0098] In the first embodiment and the second embodiment provided by the present invention, as Figure 3 As shown in (a), the shut-off valve, the upper bridge arm auxiliary valve and the lower bridge arm auxiliary valve are each composed of a plurality of auxiliary submodules connected in series and a buffer component connected in series or in parallel with each of the auxiliary submodules in the plurality of auxiliary submodules connected in series;

[0099] The auxiliary submodule is composed of a fully-controlled power electronic device, a diode connected in reverse parallel to the fully-controlled power electronic device, and a buffer component connected in series or in parallel to the fully-controlled power electronic device.

[0100] Furthermore, the reverse-resistance type fully-controlled power electronic device in the invention content is a fully-controlled power electronic device with reverse voltage blocking capability, therefore, the reverse-resistance type fully-controlled power electronic device in the auxiliary submodule does not require an anti-parallel diode; the fully-controlled power electronic devices other than the reverse-resistance type are fully-controlled power electronic devices that do not have sufficient reverse voltage capability, therefore, the fully-controlled power electronic devices other than the reverse-resistance type in the auxiliary submodule require an anti-parallel diode.

[0101] In the first embodiment and the second embodiment provided by the present invention, as Figure 3 As shown in (b), the shut-off valve, the upper bridge arm auxiliary valve and the lower bridge arm auxiliary valve are all composed of a first auxiliary branch, a buffer component and a second auxiliary branch connected in parallel;

[0102] The first auxiliary branch and the second auxiliary branch are both composed of two groups of auxiliary timing control branches connected in forward series;

[0103] The auxiliary timing control circuit is composed of a plurality of auxiliary submodules connected in series and a buffer component connected in series or in parallel with each of the plurality of auxiliary submodules connected in series;

[0104] The auxiliary submodule is composed of a fully controlled power electronic device, a diode connected in reverse parallel to the fully controlled power electronic device, and a buffer component connected in series or in parallel to the fully controlled power electronic device;

[0105] The external connection point of the first auxiliary branch and the external connection point of the second auxiliary branch are respectively the connection points of the two groups of auxiliary timing control branches of the first auxiliary branch and the connection points of the two groups of auxiliary timing control branches of the second auxiliary branch.

[0106] In the first embodiment and the second embodiment provided by the present invention, as Figure 3 As shown in (c), the shut-off valve, the upper bridge arm auxiliary valve and the lower bridge arm auxiliary valve are all composed of a first diode branch, an auxiliary branch and a second diode branch connected in parallel;

[0107] The first diode branch and the second diode branch are both composed of two groups of diode timing control branches connected in forward series;

[0108] The auxiliary branch is composed of a plurality of auxiliary submodules connected in series and a buffer component connected in series or in parallel with each of the plurality of auxiliary submodules connected in series;

[0109] The auxiliary submodule is composed of a fully controlled power electronic device, a diode connected in reverse parallel to the fully controlled power electronic device, and a buffer component connected in series or in parallel to the fully controlled power electronic device;

[0110] The external connection point of the first diode branch and the external connection point of the second diode branch are respectively connection points of two groups of diode timing control branches of the first diode branch and the second diode branch.

[0111] In the first embodiment and the second embodiment provided by the present invention, as Figure 3 As shown in (d), the shut-off valve, the upper bridge arm auxiliary valve and the lower bridge arm auxiliary valve are all composed of a third auxiliary branch and a fourth auxiliary branch connected in reverse parallel with the third auxiliary branch;

[0112] The third auxiliary branch is composed of a plurality of auxiliary submodules connected in series and a buffer component connected in series or in parallel with each of the plurality of auxiliary submodules connected in series;

[0113] The fourth auxiliary branch is composed of a capacitor connected in series, a plurality of auxiliary submodules connected in series, and a buffer component connected in series or in parallel with each of the plurality of auxiliary submodules connected in series;

[0114] The auxiliary submodule is composed of a fully-controlled power electronic device, a diode connected in reverse parallel to the fully-controlled power electronic device, and a buffer component connected in series or in parallel to the fully-controlled power electronic device.

[0115] In the first embodiment and the second embodiment provided by the present invention, as Figure 4 As shown in (a), the above-mentioned two-way valve is composed of a first thyristor branch and a second thyristor branch connected in reverse parallel thereto;

[0116] The first thyristor branch and the second thyristor branch are both composed of a plurality of thyristor modules connected in series in the forward direction;

[0117] The thyristor module consists of a thyristor and a buffer component connected in series or in parallel with the thyristor.

[0118] In the first embodiment and the second embodiment provided by the present invention, as Figure 4 As shown in (b), the above-mentioned two-way valve is composed of a first two-way valve branch and a second two-way valve branch connected in reverse parallel with the first two-way valve branch;

[0119] The first two-way valve branch and the second two-way valve branch are both composed of a first two-way valve timing control branch and a second two-way valve timing control branch connected in reverse series with the first two-way valve timing control branch;

[0120] The first two-way valve timing control branch and the second two-way valve timing control branch are both composed of a plurality of auxiliary submodules connected in series and buffer components connected in series or in parallel with each of the auxiliary submodules in the plurality of auxiliary submodules connected in series;

[0121] The auxiliary submodule is composed of a fully-controlled power electronic device, a diode connected in reverse parallel to the fully-controlled power electronic device, and a buffer component connected in series or in parallel to the fully-controlled power electronic device.

[0122] In the first embodiment and the second embodiment provided by the present invention, as Figure 4 As shown in (c), the above two-way valve is composed of a third two-way valve branch, an auxiliary branch and a fourth two-way valve branch connected in parallel;

[0123] The third two-way valve branch and the fourth two-way valve branch are both composed of two two-way valve timing control branches connected in series in a forward direction;

[0124] The two bidirectional valve timing control circuits are each composed of a plurality of diodes connected in forward series and buffer components connected in series or in parallel with the plurality of diodes connected in forward series;

[0125] The auxiliary branch is composed of a plurality of auxiliary submodules connected in series and a buffer component connected in series or in parallel with each of the plurality of auxiliary submodules connected in series;

[0126] The auxiliary submodule is composed of a fully controlled power electronic device, a diode connected in reverse parallel to the fully controlled power electronic device, and a buffer component connected in series or in parallel to the fully controlled power electronic device;

[0127] The external connection point of the third two-way valve branch and the external connection point of the fourth two-way valve branch are respectively the connection point of the two diode timing control branches of the third two-way valve branch and the connection point of the two diode timing control branches of the fourth two-way valve branch.

[0128] The fully controlled power electronic device is composed of one or more IGBT, IGCT, IEGT, GTO or MOSFET turn-off devices.

[0129] In the first embodiment and the second embodiment provided by the present invention, as Figure 5 As shown, the above-mentioned buffer component is composed of one or more types of capacitors, resistor-capacitor circuits, diodes, inductors or lightning arresters connected in series or in parallel.

[0130] Figure 6 As shown in (a), during normal commutation, the path of valve current flow, the main branch periodically bears voltage and current stress, the auxiliary valve is always in the closed state, the shut-off valve is always in the on state, and the two-way valve is always in the closed state; Sg1 is the control timing of the thyristor valve, Sg12 is the control timing of the shut-off valve, Sga1 is the control timing of the two-way valve, Sap is the control timing of the auxiliary valve, t0 is the initial triggering time, and the control period T is 2π.

[0131] Based on the same inventive concept, the present invention also provides a control method for a hybrid converter topology structure, the method comprising:

[0132] Turning on the shutoff valve of the i-th bridge arm in the hybrid converter topology structure, shutting off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, and performing the following steps;

[0133] Step 11. Turn on the thyristor valve of the i-th bridge arm in the hybrid converter topology structure, and execute step 12;

[0134] Step 12. After a control cycle T, return to step 11;

[0135] Among them, i∈[1,6].

[0136] like Figure 6 As shown in (a), the bidirectional valve includes a thyristor, which is a non-turn-off device. f When a commutation failure or short circuit fault is detected in the i-th bridge arm of the hybrid converter topology, at t fThe bidirectional valve connected to the i-th bridge arm in the hybrid converter topology is turned on at time t f The auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology is turned on at time t f At time +Δt1, the turn-off valve of the i-th bridge arm in the hybrid converter topology is turned off, and when the thyristor valve of the i-th bridge arm in the hybrid converter topology is in the forward blocking state and the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology is forced to be turned off, the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology is turned off. When t f At the end of the control cycle, step S11 is executed, until the voltage of the hybrid converter topology structure returns to stability, the switchable valve of the i-th bridge arm in the hybrid converter topology structure is turned on, the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure is turned off, and step 11 is executed;

[0137] like Figure 7 As shown in (a), step S11. Turning on the thyristor valve of the i-th bridge arm in the hybrid converter topology structure, turning on the switchable valve of the i-th bridge arm in the hybrid converter topology structure, and turning off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, after Then, execute step S12;

[0138] Step S12 turns on the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure, turns on the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, and The turnable valve of the i-th bridge arm in the hybrid converter topology structure is turned off at all times. When the thyristor valve of the i-th bridge arm in the hybrid converter topology structure is in a forward blocking state and the bidirectional valve connected to the i-th bridge arm is forced to be turned off, step S13 is executed;

[0139] Step S13: Turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, after Δt′ off Then, return to step S11;

[0140] Among them, Δt′ off The time duration during which the thyristor valve of the i-th bridge arm in the hybrid converter topology is in the forward blocking state within a control cycle of executing steps S11 to S13, Δt1 is the delay time for shutting down the switchable valve of the i-th bridge arm in the hybrid converter topology, T is a control cycle, and t0 is the start time of the control cycle.

[0141] Specifically, Figure 8 As shown in (a), t fWhen the phase switching failure occurs in the V1 valve at the moment, the two-way valve DVa and the auxiliary valve Vp are triggered at the same time. After Δt1 time, the shut-off valve Vg1 is closed to realize the flow switching from the main bridge arm to the auxiliary bridge arm. Figure 8 As shown in (b), after the main bridge arm current passes through zero, the V1 thyristor valve is turned off and begins to bear the reverse voltage, and the V1 valve current is completely transferred to the auxiliary valve; Figure 8 As shown in (c), t f At +Δt2, the auxiliary valve Vp starts to shut down, and all the current is transferred to the V3 valve to complete the phase change. Δt2 is the conduction time of the auxiliary valve.

[0142] Based on the same inventive concept, the present invention also provides a control method for a hybrid converter topology structure, such as Figure 7 In (a), the method comprises:

[0143] Step S21. Turn on the thyristor valve of the i-th bridge arm in the hybrid converter topology, turn on the switchable valve of the i-th bridge arm in the hybrid converter topology, and turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology. Then, execute step S22;

[0144] Step S22. Turn on the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure, turn on the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, The switchable valve of the i-th bridge arm in the hybrid converter topology is turned off at all times. When the thyristor valve of the i-th bridge arm in the hybrid converter topology is in a forward blocking state and the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology is forced to be turned off, step S23 is executed;

[0145] Step S23: Turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, after ΔT' off Then, return to step S21;

[0146] Where, ΔT' off is the duration that the thyristor valve of the i-th bridge arm in the hybrid converter topology is in the forward blocking state within a control cycle, Δt1 is the delay duration for shutting off the switchable valve of the i-th bridge arm in the hybrid converter topology, T is a control cycle, and t0 is the start time of the control cycle.

[0147] Based on the same inventive concept, the present invention also provides a control method for a hybrid converter topology structure, the method comprising:

[0148] Turning on the shutoff valve of the i-th bridge arm in the hybrid converter topology, shutting off the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology, shutting off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology, and performing the following steps;

[0149] Step 21. Turn on the thyristor valve of the i-th bridge arm in the hybrid converter topology structure, and execute step 22;

[0150] Step 22. Return to step 21 after a control cycle T; wherein, i∈[1,6].

[0151] like Figure 6 As shown in (b), the two-way valve is a fully controlled device. f When a commutation failure or short circuit fault is detected in the i-th bridge arm of the hybrid converter topology, at t f The bidirectional valve connected to the i-th bridge arm in the hybrid converter topology is turned on at time t f The auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology is turned on at time t f At time +Δt1, the turnable valve of the i-th bridge arm in the hybrid converter topology is turned off, and when the thyristor valve of the i-th bridge arm in the hybrid converter topology is in the forward blocking state, the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology is turned off, and the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology is turned off. When t f At the end of the control cycle, step T11 is executed until the voltage of the hybrid converter topology structure returns to stability, the switchable valve of the i-th bridge arm in the hybrid converter topology structure is turned on, the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure is turned off, the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure is turned off, and step 21 is executed;

[0152] Step T11. Turn on the thyristor valve of the i-th bridge arm in the hybrid converter topology, turn on the switchable valve of the i-th bridge arm in the hybrid converter topology, turn off the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology, turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology, and then Then, execute step T12;

[0153] Step T12. Turn on the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure, turn on the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, Turning off the turnable valve of the i-th bridge arm in the hybrid converter topology structure at all times, when the thyristor valve of the i-th bridge arm in the hybrid converter topology structure is in a forward blocking state, executing step T13;

[0154] Step T13. Turn off the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure, turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, and after Δt" off Then, return to step T11;

[0155] Where, Δt” off The time duration during which the thyristor valve of the i-th bridge arm in the hybrid converter topology is in the forward blocking state within a control cycle of executing step T11 to step T13, Δt1 is the delay time for shutting down the switchable valve of the i-th bridge arm in the hybrid converter topology, and T is a control cycle.

[0156] Based on the same inventive concept, the present invention also provides a control method for a hybrid converter topology structure, such as Figure 7 As shown in (b), the method comprises:

[0157] Step T21. Turn on the thyristor valve of the i-th bridge arm in the hybrid converter topology, turn on the switchable valve of the i-th bridge arm in the hybrid converter topology, turn off the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology, turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology, and then Then, execute step T22;

[0158] Step T22. Turn on the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure, turn on the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, Turning off the turnable valve of the i-th bridge arm in the hybrid converter topology structure at all times, when the thyristor valve of the i-th bridge arm in the hybrid converter topology structure is in a forward blocking state, executing step T23;

[0159] Step T23. Turn off the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure, turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, and after ΔT' off Then, return to step T21;

[0160] Where, ΔT' off is the time duration that the thyristor valve of the i-th bridge arm in the hybrid converter topology is in the forward blocking state within one control cycle, Δt1 is the delay time for shutting off the switchable valve of the i-th bridge arm in the hybrid converter topology, and T is one control cycle.

[0161] In summary, the present invention relates to a hybrid converter topology structure with auxiliary commutation on the DC side and a control method thereof, comprising: a three-phase six-bridge arm circuit and an auxiliary commutation circuit with forward current controllable shutdown and forward and reverse voltage blocking capabilities connected in parallel to the DC side of the three-phase six-bridge arm circuit; the auxiliary commutation circuit is connected to the connection points of the upper bridge arm and the lower bridge arm of each phase bridge arm circuit in the three-phase six-bridge arm circuit through a two-way valve on each phase AC bus in the three-phase AC bus; the auxiliary commutation circuit added by the present invention can transfer the commutation current and flexibly control the commutation time when the converter commutation fails, and utilizes the large current shutdown characteristics of the turn-off device to quickly restore the commutation between the two bridge arms, greatly speeding up the commutation failure recovery. The recovery time of the rear converter; the shut-off valve introduced into the main bridge arm of the present invention is shut down in case of a fault, so that the current of the main bridge arm is zero, and at the same time a reverse voltage is provided, which increases the switching time area of ​​the thyristor valve to ensure its reliable shutdown. The voltage stress is mainly borne by the thyristor valve, and the number of series stages is small, so the device loss is low; the bidirectional valve of the present invention provides a transfer path for the main bridge arm current to switch to the auxiliary switching circuit in case of a fault, and by controlling the opening direction of the bidirectional valve, the upper and lower bridge arms of each phase are switched to the auxiliary switching circuit respectively; when the hybrid converter topology structure of the present invention adopts an alternating operation control method, it can avoid the occurrence of short-circuit current and switching failure, thereby improving the overall reliability of the converter.

[0162] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0163] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0164] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0165] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0166] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A hybrid converter topology with DC side auxiliary commutation, characterized in that: The topological structure includes: a three-phase six-bridge arm circuit and an auxiliary commutation circuit connected in parallel with the DC side of the three-phase six-bridge arm circuit and having forward current controllable shutdown and forward and reverse voltage blocking capabilities; The auxiliary commutation circuit is respectively connected to the connection points of the upper bridge arm and the lower bridge arm of each phase bridge arm circuit in the three-phase six-bridge arm circuit through a two-way valve with two-way opening and two-way pressure resistance capabilities on each phase AC bus in the three-phase AC bus; The upper bridge arm and the lower bridge arm of each phase bridge arm circuit in the three-phase six-bridge arm circuit are composed of a thyristor valve connected in series and a turn-off valve with forward current controllable turn-off and forward voltage blocking capabilities; The auxiliary commutation circuit is a three-phase six-bridge arm structure; Each phase bridge arm structure in the three-phase six-bridge arm structure is composed of an upper bridge arm auxiliary valve and a lower bridge arm auxiliary valve connected in series; The connection points between the upper bridge arm auxiliary valve and the lower bridge arm auxiliary valve of each phase bridge arm structure in the three-phase six-bridge arm structure are respectively connected to the connection points of the upper bridge arm and the lower bridge arm of each phase bridge arm circuit in the three-phase six-bridge arm circuit through the two-way valves on each phase AC bus in the three-phase AC bus.

2. The topological structure according to claim 1, characterized in that: The thyristor valve is composed of a plurality of thyristors and a buffer component connected in series or in parallel with each of the plurality of thyristors.

3. The topological structure according to claim 1, characterized in that: The shut-off valve, the upper bridge arm auxiliary valve and the lower bridge arm auxiliary valve are each composed of a plurality of auxiliary submodules connected in series and a buffer component connected in series or in parallel with each of the auxiliary submodules in the plurality of auxiliary submodules connected in series; The auxiliary submodule is composed of one or more fully-controlled power electronic devices with reverse voltage blocking capability, or is composed of a fully-controlled power electronic device without reverse voltage blocking capability, a diode connected in reverse parallel to the fully-controlled power electronic device without reverse voltage blocking capability, and a buffer component connected in series or in parallel with the fully-controlled power electronic device without reverse voltage blocking capability.

4. The topological structure according to claim 1, characterized in that: The shut-off valve, the upper bridge arm auxiliary valve and the lower bridge arm auxiliary valve are all composed of a first auxiliary branch, a buffer component and a second auxiliary branch connected in parallel; The first auxiliary branch and the second auxiliary branch are both composed of two groups of auxiliary timing control branches connected in forward series; The auxiliary timing control branch is composed of a plurality of auxiliary sub-modules connected in series and a buffer component connected in series or in parallel with each of the plurality of auxiliary sub-modules connected in series; The auxiliary submodule is composed of one or more fully controlled power electronic devices with reverse voltage blocking capability, or is composed of a fully controlled power electronic device without reverse voltage blocking capability, a diode connected in reverse parallel to the fully controlled power electronic device without reverse voltage blocking capability, and a buffer component connected in series or in parallel to the fully controlled power electronic device without reverse voltage blocking capability; The external connection point of the first auxiliary branch and the external connection point of the second auxiliary branch are respectively the connection points of the two groups of auxiliary timing control branches of the first auxiliary branch and the connection points of the two groups of auxiliary timing control branches of the second auxiliary branch.

5. The topological structure according to claim 1, characterized in that: The shut-off valve, the upper bridge arm auxiliary valve and the lower bridge arm auxiliary valve are all composed of a first diode branch, an auxiliary branch and a second diode branch connected in parallel; The first diode branch and the second diode branch are both composed of two groups of diode timing control branches connected in forward series; The auxiliary branch is composed of a plurality of auxiliary submodules connected in series and a buffer component connected in series or in parallel with each of the plurality of auxiliary submodules connected in series; The auxiliary submodule is composed of one or more fully controlled power electronic devices with reverse voltage blocking capability, or is composed of a fully controlled power electronic device without reverse voltage blocking capability, a diode connected in reverse parallel to the fully controlled power electronic device without reverse voltage blocking capability, and a buffer component connected in series or in parallel to the fully controlled power electronic device without reverse voltage blocking capability; The external connection point of the first diode branch and the external connection point of the second diode branch are respectively connection points of two groups of diode timing control branches of the first diode branch and the second diode branch.

6. The topological structure according to claim 1, characterized in that: The shut-off valve, the upper bridge arm auxiliary valve and the lower bridge arm auxiliary valve are all composed of a third auxiliary branch and a fourth auxiliary branch connected in reverse parallel with the third auxiliary branch; The third auxiliary branch is composed of a plurality of auxiliary submodules connected in series and a buffer component connected in series or in parallel with each of the plurality of auxiliary submodules connected in series; The fourth auxiliary branch is composed of a capacitor connected in series, a plurality of auxiliary submodules connected in series, and a buffer component connected in series or in parallel with each of the plurality of auxiliary submodules connected in series; The auxiliary submodule is composed of one or more fully-controlled power electronic devices with reverse voltage blocking capability, or is composed of a fully-controlled power electronic device without reverse voltage blocking capability, a diode connected in reverse parallel to the fully-controlled power electronic device without reverse voltage blocking capability, and a buffer component connected in series or in parallel with the fully-controlled power electronic device without reverse voltage blocking capability.

7. The topological structure according to claim 1, characterized in that: The bidirectional valve is composed of a first thyristor branch and a second thyristor branch connected in reverse parallel thereto; The first thyristor branch and the second thyristor branch are both composed of a plurality of thyristor modules connected in series in the forward direction; The thyristor module consists of a thyristor and a buffer component connected in series or in parallel with the thyristor.

8. The topological structure according to claim 1, characterized in that: The two-way valve is composed of a first two-way valve branch and a second two-way valve branch connected in reverse parallel with the first two-way valve branch; The first two-way valve branch and the second two-way valve branch are both composed of a first two-way valve timing control branch and a second two-way valve timing control branch connected in reverse series with the first two-way valve timing control branch; The first two-way valve timing control branch and the second two-way valve timing control branch are both composed of a plurality of auxiliary submodules connected in series and buffer components connected in series or in parallel with each of the auxiliary submodules in the plurality of auxiliary submodules connected in series; The auxiliary submodule is composed of one or more fully-controlled power electronic devices with reverse voltage blocking capability, or is composed of a fully-controlled power electronic device without reverse voltage blocking capability, a diode connected in reverse parallel to the fully-controlled power electronic device without reverse voltage blocking capability, and a buffer component connected in series or in parallel with the fully-controlled power electronic device without reverse voltage blocking capability.

9. The topological structure according to claim 1, characterized in that: The two-way valve is composed of a third two-way valve branch, an auxiliary branch and a fourth two-way valve branch connected in parallel; The third two-way valve branch and the fourth two-way valve branch are both composed of two two-way valve timing control branches connected in series in a forward direction; The two bidirectional valve timing control branches are each composed of a plurality of diodes connected in forward series and buffer components connected in series or in parallel with the plurality of diodes connected in forward series; The auxiliary branch is composed of a plurality of auxiliary submodules connected in series and a buffer component connected in series or in parallel with each of the plurality of auxiliary submodules connected in series; The auxiliary submodule is composed of one or more fully controlled power electronic devices with reverse voltage blocking capability, or is composed of a fully controlled power electronic device without reverse voltage blocking capability, a diode connected in reverse parallel to the fully controlled power electronic device without reverse voltage blocking capability, and a buffer component connected in series or in parallel to the fully controlled power electronic device without reverse voltage blocking capability; The external connection point of the third two-way valve branch and the external connection point of the fourth two-way valve branch are respectively the connection point of the two diode timing control branches of the third two-way valve branch and the connection point of the two diode timing control branches of the fourth two-way valve branch.

10. The topological structure according to any one of claims 2, 7 to 9, characterized in that: The buffer component is composed of one or more types of capacitors, resistor-capacitor circuits, diodes, inductors or lightning arresters connected in series or in parallel.

11. A method for controlling a topological structure according to any one of claims 1 to 10, characterized in that: The method comprises: Turning on the shutoff valve of the i-th bridge arm in the hybrid converter topology structure, shutting off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, and performing the following steps; Step 11. Turn on the thyristor valve of the i-th bridge arm in the hybrid converter topology structure, and execute step 12; Step 12. After a control cycle T, return to step 11; Among them, i∈[1,6].

12. The method according to claim 11, characterized in that When at t f When a commutation failure or short circuit fault is detected in the i-th bridge arm of the hybrid converter topology, at t f The bidirectional valve connected to the i-th bridge arm in the hybrid converter topology is turned on at time t f The auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology is turned on at time t f At time +Δt1, the turn-off valve of the i-th bridge arm in the hybrid converter topology is turned off, and when the thyristor valve of the i-th bridge arm in the hybrid converter topology is in the forward blocking state and the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology is forced to be turned off, the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology is turned off. When t f At the end of the control cycle, step S11 is executed, until the voltage of the hybrid converter topology structure returns to stability, the switchable valve of the i-th bridge arm in the hybrid converter topology structure is turned on, the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure is turned off, and step 11 is executed; Step S11. Turn on the thyristor valve of the i-th bridge arm in the hybrid converter topology, turn on the switchable valve of the i-th bridge arm in the hybrid converter topology, and turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology. Then, execute step S12; Step S12 turns on the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure, turns on the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, and The turnable valve of the i-th bridge arm in the hybrid converter topology structure is turned off at all times. When the thyristor valve of the i-th bridge arm in the hybrid converter topology structure is in a forward blocking state and the bidirectional valve connected to the i-th bridge arm is forced to be turned off, step S13 is executed; Step S13: Turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, after Δt o ' ff Then, return to step S11; Among them, Δt o ' ff The duration during which the thyristor valve of the i-th bridge arm in the hybrid converter topology is in the forward blocking state within a control cycle of executing steps S11 to S13, Δt1 is the delay duration for shutting down the switchable valve of the i-th bridge arm in the hybrid converter topology, and T is a control cycle.

13. A method for controlling a topological structure according to any one of claims 1 to 10, characterized in that: The method comprises: Step S21. Turn on the thyristor valve of the i-th bridge arm in the hybrid converter topology, turn on the switchable valve of the i-th bridge arm in the hybrid converter topology, and turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology. Then, execute step S22; Step S22. Turn on the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure, turn on the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, The switchable valve of the i-th bridge arm in the hybrid converter topology is turned off at all times. When the thyristor valve of the i-th bridge arm in the hybrid converter topology is in a forward blocking state and the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology is forced to be turned off, step S23 is executed; Step S23: Turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, after ΔT o ' ff Then, return to step S21; Where i∈[1,6], ΔT o ' ff is the time duration that the thyristor valve of the i-th bridge arm in the hybrid converter topology is in the forward blocking state within one control cycle, Δt1 is the delay time for shutting off the switchable valve of the i-th bridge arm in the hybrid converter topology, and T is one control cycle.

14. A method for controlling a topological structure according to any one of claims 1 to 10, characterized in that: The method comprises: Turning on the shutoff valve of the i-th bridge arm in the hybrid converter topology, shutting off the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology, shutting off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology, and performing the following steps; Step 21. Turn on the thyristor valve of the i-th bridge arm in the hybrid converter topology structure, and execute step 22; Step 22. After a control cycle T, return to step 21; Among them, i∈[1,6].

15. The method according to claim 14, characterized in that When at t f When a commutation failure or short circuit fault is detected in the i-th bridge arm of the hybrid converter topology, at t f The bidirectional valve connected to the i-th bridge arm in the hybrid converter topology is turned on at time t f The auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology is turned on at time t f At time +Δt1, the turnable valve of the i-th bridge arm in the hybrid converter topology is turned off, and when the thyristor valve of the i-th bridge arm in the hybrid converter topology is in the forward blocking state, the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology is turned off, and the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology is turned off. When t f At the end of the control cycle, step T11 is executed until the voltage of the hybrid converter topology structure returns to stability, the switchable valve of the i-th bridge arm in the hybrid converter topology structure is turned on, the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure is turned off, the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure is turned off, and step 21 is executed; Step T11. Turn on the thyristor valve of the i-th bridge arm in the hybrid converter topology, turn on the switchable valve of the i-th bridge arm in the hybrid converter topology, turn off the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology, turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology, and then Then, execute step T12; Step T12. Turn on the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure, turn on the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, Turning off the turnable valve of the i-th bridge arm in the hybrid converter topology structure at all times, when the thyristor valve of the i-th bridge arm in the hybrid converter topology structure is in a forward blocking state, executing step T13; Step T13. Turn off the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure, turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, and after Δt' o ' ff Then, return to step T11; Where Δt' o ' ff The time duration during which the thyristor valve of the i-th bridge arm in the hybrid converter topology is in the forward blocking state within a control cycle of executing step T11 to step T13, Δt1 is the delay time for shutting down the switchable valve of the i-th bridge arm in the hybrid converter topology, and T is a control cycle.

16. A method for controlling a topological structure according to any one of claims 1 to 10, characterized in that: The method comprises: Step T21. Turn on the thyristor valve of the i-th bridge arm in the hybrid converter topology, turn on the switchable valve of the i-th bridge arm in the hybrid converter topology, turn off the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology, turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology, and then Then, execute step T22; Step T22. Turn on the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure, turn on the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, Turning off the turnable valve of the i-th bridge arm in the hybrid converter topology structure at all times, when the thyristor valve of the i-th bridge arm in the hybrid converter topology structure is in a forward blocking state, executing step T23; Step T23. Turn off the bidirectional valve connected to the i-th bridge arm in the hybrid converter topology structure, turn off the auxiliary valve of the auxiliary commutation circuit connected to the i-th bridge arm in the hybrid converter topology structure, and after ΔT o ' ff Then, return to step T21; Where i∈[1,6], ΔT o ' ff is the time duration that the thyristor valve of the i-th bridge arm in the hybrid converter topology is in the forward blocking state within one control cycle, Δt1 is the delay time for shutting off the switchable valve of the i-th bridge arm in the hybrid converter topology, and T is one control cycle.

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