WO2021139119A1 - Hybrid converter with controllable turn-off at alternating-current side, and control method - Google Patents

Abstract

Disclosed are a hybrid converter with controllable turn-off at an alternating-current side, and a control method. The hybrid converter with controllable turn-off at an alternating-current side comprises three parallel branches, three bidirectional turn-off valves, and a converter transformer; each branch consists of a thyristor valve branch and an auxiliary valve branch which are connected in parallel; the thyristor valve branch consists of two thyristor valves connected in series, and the auxiliary valve branch consists of two auxiliary valves connected in series and having the capability of controllable turn-off of a forward current and the capability of blocking forward and reverse voltages; a connection point between the two thyristor valves serially connected is connected to one end of a bidirectional controllable turn-off valve, and the other end of the bidirectional controllable turn-off valve is connected to a connection point between the two auxiliary valves serially connected and having the capability of controllable turn-off of a forward current and the capability of blocking forward and reverse voltages and to an output end of the converter transformer.

Description

Hybrid inverter with controllable shut-off on AC side and control method

This application claims the priority of a Chinese patent application filed with the Chinese Patent Office with an application number of 202010027411.5 on January 10, 2020, and the entire content of this application is incorporated into this application by reference.

Technical field

This application relates to the technical field of power electronic commutation, for example, to a hybrid converter with a controllable shutdown on the AC side and a control method.

Background technique

Grid-commutated high voltage direct current (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 worldwide. As the core equipment of DC transmission, the converter is the core functional unit to realize the conversion of AC and DC power. Its operational reliability largely determines the operational reliability of the UHV DC grid. Since most of the converters use semi-controlled device thyristors as the core components to form a six-pulse bridge commutation topology, each bridge arm is composed of multi-stage thyristors and their buffer components in series. Because the thyristors do not have the ability to self-shut down, the AC system fails Under such circumstances, commutation failure is prone to occur, leading to a rapid increase in DC current and rapid and large loss of DC transmission power, which brings more severe challenges to the safe and stable operation of the power grid.

In view of the commutation failure of DC transmission, a variety of converter topologies with the function of resisting commutation failure have been developed. One is the Capacitor Commutation Converter (CCC) topology, which uses capacitor voltage to increase the time area of the valve commutation voltage to ensure reliable shutdown. Based on the basic principle of the capacitor commutation circuit, a variety of topological structures have been developed. The controllable capacitor module is formed by the combination of power electronic switches and capacitors to realize the capacitor input and the controllable voltage direction. In order to achieve reliable commutation, the single-stage capacitor value If it is larger, it will increase the voltage and current stress of the thyristor, the core component of the valve. Therefore, it is difficult to realize the above-mentioned topology engineering based on capacitor commutation. The other is to form a hybrid converter by connecting a switchable device in series with a thyristor, so that each bridge arm of the converter has the ability to switch off, avoiding the occurrence of commutation failure. Due to the large transmission capacity of conventional DC transmission, the commutation Each bridge arm of the device bears high voltage and large current. In this topology, the shut-off pipe valve needs to be realized in a multi-stage series-parallel connection. At the same time, the shut-off pipe valve can withstand large currents for a long time, and its loss is relatively large; When the high current is turned off, it bears higher voltage stress, and the number of series series increases; the engineering realization cost and difficulty of this kind of technical solution are relatively high.

Summary of the invention

This application provides a hybrid inverter with controllable shutdown on the AC side and a control method. A bidirectional shutoff valve is introduced on the AC side to ensure that the thyristor valve has sufficient reverse recovery time to reliably shut down, and at the same time, an auxiliary valve is used to assist Commutation fundamentally solves the problem of commutation failure in the DC system.

The embodiment of the present application provides a hybrid converter with controllable shutdown on the AC side, including three parallel branches, three bidirectional shut-off valves, and a converter transformer;

Each branch is composed of parallel thyristor valve branch and auxiliary valve branch;

The thyristor valve branch is composed of two series-connected thyristor valves, and the auxiliary valve branch is composed of two series-connected auxiliary valves with controllable shut-off of forward current and blocking capability of forward and reverse voltage;

The connection point between the two series-connected thyristor valves is connected to one end of a two-way shut-off valve, and the other end of the two-way shut-off valve is respectively connected with the two series-connected forward current controllable shut-off valves. Connect to the connection point between the auxiliary valve with forward and reverse voltage blocking capability and the output terminal of the converter transformer.

The embodiment of the present application also provides a control method of a hybrid inverter with a controllable shutdown on the AC side, including:

When the two-way shutoff valve connected to the i-th thyristor valve of the converter is in the on state, and the auxiliary valve connected to the i-th thyristor valve is in the off state, every other control The i-th thyristor valve is periodically turned on once; where i∈[1,6].

The embodiment of the present application also provides another control method of a hybrid inverter with a controllable shutdown on the AC side, including:

Turn on the i th thyristor valve of the converter, turn on the bidirectional shut-off valve connected to the i th thyristor valve, and turn off the auxiliary valve connected to the i th thyristor valve;

After Δt, the bidirectional shut-off valve connected to the i-th thyristor valve is turned off, and the auxiliary valve connected to the i-th thyristor valve is turned on;

When the i-th thyristor valve is in the positive blocking state, turn off the auxiliary valve connected to the i-th thyristor valve, and after Δt″ _off , return to perform the opening of the i-th thyristor valve , The step of turning on the bidirectional shut-off valve connected to the i-th thyristor valve, and shutting off the auxiliary valve connected to the i-th thyristor valve;

Where Δt″ _off is the length of time the i-th thyristor valve is in the positive blocking state in a control period, Δt is the bidirectional shut-off valve connected to the i-th thyristor valve,

T is a control period, i∈[1,6].

Description of the drawings

FIG. 1 is a schematic diagram of a topological structure of a hybrid converter with a controllable shutdown on the AC side according to an embodiment of the present application;

2 is a schematic structural diagram of an auxiliary valve provided by an embodiment of the present application;

Fig. 3 is a schematic structural diagram of a bidirectional shut-off valve provided by an embodiment of the present application;

FIG. 4 is a schematic structural diagram of a buffer device provided by an embodiment of the present application;

FIG. 5 is a current flow path diagram of a hybrid converter topology with a controllable shutdown on the AC side according to an embodiment of the present application during normal operation;

FIG. 6 is a control sequence diagram of a hybrid converter topology with a controllable shutdown on the AC side provided by an embodiment of the present application during normal operation;

FIG. 7 is a current flow path diagram when the topology of a hybrid converter with a controllable shutdown on the AC side according to an embodiment of the present application fails; FIG.

FIG. 8 is a control sequence diagram of a hybrid converter with a controllable shutdown on the AC side according to an embodiment of the present application when the topology structure fails;

Fig. 9 is a control sequence diagram of a hybrid converter topology with controllable shutdown on the AC side provided by an embodiment of the present application.

Detailed ways

The specific implementation manners of the present application will be described below with reference to the accompanying drawings.

The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. The described embodiments are part of the embodiments of the present application, rather than all of the embodiments.

This application provides a hybrid converter topology with controllable shutdown on the AC side. As shown in FIG. 1, the topology includes three parallel branches, three bidirectional shut-off valves, and a converter transformer. ；

Each branch is composed of parallel thyristor valve branch and auxiliary valve branch;

The thyristor valve branch is composed of two series-connected thyristor valves, and the auxiliary valve branch is composed of two series-connected auxiliary valves with controllable shut-off of forward current and blocking capability of forward and reverse voltage;

The connection point between the two series-connected thyristor valves is connected to one end of the two-way shut-off valve, and the other end of the two-way shut-off valve is connected to the connection point between the two series-connected auxiliary valves and the output end of the converter transformer. .

In Figure 1, V11, V21, V31, V41, V51, and V61 are thyristor valves, V13, V23, V33, V43, V53, and V63 are auxiliary valves, and V14, V36, and V52 are bidirectional shut-off valves.

The topology of the embodiments of the present application will be explained below in conjunction with specific embodiments.

In the embodiment of the present application, the thyristor valve is composed of a plurality of thyristors and a buffer component connected in series or in parallel with each thyristor.

In the embodiment of the present application, as shown in a in FIG. 2, the above-mentioned auxiliary valve VN3 (N=1, 2, 3, 4, 5, 6) is composed of a plurality of first auxiliary sub-modules connected in series and connected with each other respectively. Each of the plurality of first auxiliary sub-modules connected in series is composed of buffer components connected in series or in parallel.

The first auxiliary sub-module is composed of a power module, or is composed of a power module and a diode connected in series with the power module.

The power module is composed of one or more of fully-controlled power electronic devices with reverse voltage blocking capability, or is composed of fully-controlled power electronic devices without reverse voltage blocking capability and is not compatible with the A fully-controlled power electronic device with reverse voltage blocking capability is composed of anti-parallel diodes.

The fully-controlled power electronic device consists of an insulated gate bipolar transistor (IGBT), an integrated gate-commutated thyristor (IGCT), and an injection enhanced gate transistor (Injection Enhanced Gate Transistor). , IEGT), Gate Turn-Off Thyristor (GTO) and Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) and other devices that can be turned off. Kind of composition.

In the embodiment of the present application, as shown in b in FIG. 2, the above-mentioned auxiliary valve VN3 (N=1, 2, 3, 4, 5, 6) is composed of a series-connected auxiliary timing control branch and a diode branch.

The diode branch is composed of a plurality of forward-series diodes and a buffer component connected in series or in parallel with each of the plurality of forward-series diodes.

The auxiliary timing control branch is composed of a plurality of power modules connected in series and a buffer component connected in series or in parallel with each of the power modules connected in series.

The power module is composed of one or more of fully-controlled power electronic devices with reverse voltage blocking capability, or is composed of fully-controlled power electronic devices without reverse voltage blocking capability and is not compatible with the A fully-controlled power electronic device with reverse voltage blocking capability is composed of anti-parallel diodes.

The fully-controlled power electronic device is composed of one or more of turn-off devices such as IGBT, IGCT, IEGT, GTO, and MOSFET.

In the embodiment of the present application, as shown in c in FIG. 2, the above-mentioned auxiliary valve VN3 (N=1, 2, 3, 4, 5, 6) is composed of a plurality of first power electronic units connected in series.

The first power electronic unit is 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 sets of auxiliary timing control branches connected in series in a forward direction.

The auxiliary timing control branch is composed of a plurality of power modules connected in series and a buffer component connected in series or in parallel with each of the power modules connected in series.

The power module is composed of one or more of fully-controlled power electronic devices with reverse voltage blocking capability, or is composed of fully-controlled power electronic devices without reverse voltage blocking capability and is not compatible with the A fully-controlled power electronic device with reverse voltage blocking capability is composed of anti-parallel diodes.

The connection points of the two sets of auxiliary timing control branches of the first auxiliary branch and the connection points of the two sets of auxiliary timing control branches of the second auxiliary branch are both external connection points of the auxiliary valve or with the auxiliary valve. The connection point of the other first power electronic unit in the valve.

The fully-controlled power electronic device is composed of one or more of turn-off devices such as IGBT, IGCT, IEGT, GTO, and MOSFET.

In the embodiment of the present application, as shown in d in FIG. 2, the above-mentioned auxiliary valve VN3 (N=1, 2, 3, 4, 5, 6) is composed of a plurality of second power electronic units connected in series.

The second power electronic unit is composed of a third auxiliary branch connected in parallel, an auxiliary timing control branch, a buffer component and a fourth auxiliary branch.

Both the third auxiliary branch and the fourth auxiliary branch are composed of two groups of diode branches connected in series in a forward direction.

The diode branch is composed of a plurality of forward-series diodes and a buffer component connected in series or in parallel with each of the plurality of forward-series diodes.

The auxiliary timing control branch is composed of a plurality of power modules connected in series and a buffer component connected in series or in parallel with each of the power modules connected in series.

The power module is composed of one or more of fully-controlled power electronic devices with reverse voltage blocking capability, or is composed of fully-controlled power electronic devices without reverse voltage blocking capability and is not compatible with the A fully-controlled power electronic device with reverse voltage blocking capability is composed of anti-parallel diodes.

The connection points of the two groups of diode branches of the third auxiliary branch and the connection points of the two groups of diode branches of the fourth auxiliary branch are both external connection points of the auxiliary valve or in the auxiliary valve Connection point for other second power electronic units.

In the embodiment of the present application, as shown in a in FIG. 3, the above-mentioned two-way shut-off valve consists of a first two-way shut-off valve branch and a second two-way shut-off valve branch in reverse series with the first two-way shut-off valve branch. It is composed of a branch circuit with a shut-off valve.

The first two-way shut-off valve branch and the second two-way shut-off valve branch are each composed of a plurality of second auxiliary sub-modules connected in series and each second auxiliary sub-module connected in series with each second Auxiliary sub-modules are composed of buffer components connected in series or in parallel.

The second auxiliary sub-module is composed of one or more of fully-controlled power electronic devices with reverse voltage blocking capability, or is composed of fully-controlled power electronic devices without reverse voltage blocking capability, and The fully-controlled power electronic device without reverse voltage blocking capability is composed of a diode in reverse parallel connection and a buffer component connected in series or parallel with the fully-controlled power electronic device without reverse voltage blocking capability. Figure 3 a shows the two structures of the two-way shut-off valve.

Fully-controlled power electronic devices are composed of one or more of the turn-off devices such as IGBT, IGCT, IEGT, GTO, and MOSFET.

In the embodiment of the present application, as shown in b in Figure 3, the above-mentioned two-way shut-off valve consists of a third two-way shut-off valve branch, a fifth auxiliary branch, and a fourth two-way shut-off valve branch connected in parallel. composition.

The third two-way shut-off valve branch and the fourth two-way shut-off valve branch are both composed of two two-way shut-off valve timing control branches connected in series in a positive direction.

The two-way turn-off valve timing control branch is composed of a plurality of forward-series diodes and a buffer component connected in series or parallel with each forward-series diode.

The fifth auxiliary branch is composed of a plurality of second auxiliary submodules connected in series and a buffer component connected in series or in parallel with each of the plurality of second auxiliary submodules connected in series.

The second auxiliary sub-module is composed of one or more of fully-controlled power electronic devices with reverse voltage blocking capability, or is composed of fully-controlled power electronic devices without reverse voltage blocking capability, and The fully-controlled power electronic device without reverse voltage blocking capability is composed of a diode in reverse parallel connection and a buffer component connected in series or parallel with the fully-controlled power electronic device without reverse voltage blocking capability.

The external connection points of the third two-way shut-off valve branch and the external connection points of the fourth two-way shut-off valve branch are respectively two diode timing control branches of the third two-way shut-off valve branch The connection point of and the connection point of the two diode timing control branches of the fourth bidirectional shut-off valve branch.

Fully-controlled power electronic devices are composed of one or more of the turn-off devices such as IGBT, IGCT, IEGT, GTO, and MOSFET.

As shown in c in Figure 3, the two-way shut-off valve is composed of two fifth two-way shut-off valve branches connected in anti-parallel.

The fifth bidirectional shut-off valve branch is composed of a plurality of full-control power electronic devices connected in series in a forward direction and a buffer component connected in series or in parallel with each full-control power electronic device.

As shown in Figure 3 d, the two-way shut-off valve is composed of multiple power device modules connected in series.

The power device module is composed of two anti-parallel fully-controlled power electronic devices and a buffer component connected in series or in parallel with each fully-controlled power electronic device.

As shown in Figure 4, the buffer component is composed of one or more of capacitors, resistance-capacitance circuits, diodes, inductors, and arresters in series or in parallel. Based on the basic knowledge of the device, the structure shown in c and d in Figure 3, when the buffer component is selected, diodes are not used, that is, the two structures do not include the structure of the fully-controlled power electronic device and the diode in series or parallel.

The fully-controlled power electronic device is composed of one or more of turn-off devices such as IGBT, IGCT, IEGT, GTO, and MOSFET.

The embodiment of the present application also provides a method for controlling the topology structure as described above, and the method includes:

Turn on the bidirectional shut-off valve connected to the i-th thyristor valve, turn off the auxiliary valve connected to the i-th thyristor valve, and perform the following steps:

Step 1: Turn on the i-th thyristor valve, and go to step 2.

Step 2: Return to step 1 after a control period T; where i∈[1,6].

As shown in Figure 5, it is the path through which the valve current flows during normal operation. The thyristor valve is periodically subjected to voltage and current stress, and the auxiliary valve is always in the off state; as shown in Figure 6, it is the path of multiple valves in normal operation. Control sequence, where Sg1 is the control sequence of the thyristor valve, Sg12 is the control sequence of the bidirectional shut-off valve, Sg13 is the control sequence of the auxiliary valve, t ₀ is the initial trigger time, Δt _on is the conduction time of the thyristor valve, Δt _off is the off time of the thyristor valve, Δt' _off is the positive blocking time of the thyristor valve, and the control period T is 2π.

When t _f detecting the moment of the i th thyristor valve occurs commutation failure or a short-circuit failure, t _f + Δt ₁ time the auxiliary valve is turned on and the i-th thyristor valve is connected and turned off at t _f + Δt ₂ time The bidirectional shut-off valve connected to the i-th thyristor valve, when the i-th thyristor valve is in the positive blocking state, shuts off the auxiliary valve connected to the i-th thyristor valve, as shown in Figure 7, the process is divided into There are three stages. Figure 7a shows the commutation stage of the main branch to the auxiliary valve. In this stage, the auxiliary valve receives the trigger signal and turns on, and then the two-way shut-off valve receives the signal to turn off, completing the main branch to the auxiliary valve. Valve commutation process; Figure 7 b shows the main branch to close the auxiliary valve flow stage, at this stage the main branch has been completely shut off, all the current is transferred to the auxiliary valve; Figure 7 c shows the main branch And the auxiliary valve shut-off stage, at this stage the auxiliary valve receives the shut-off signal and shuts off the auxiliary valve. At this time, the thyristor valve is in a positive blocking state to withstand the forward voltage. Figure 8 shows the control sequence of multiple valves when a commutation failure or short circuit fault is detected. Sg1 is the control sequence of the thyristor valve, Sg12 is the control sequence of the bidirectional shut-off valve, Sg13 is the control sequence of the auxiliary valve, t ₁ is the initial trigger time, the control period T is 2π, Δt ₁ is the delay time for turning on the auxiliary valve of the i-th bridge arm, and Δt ₂ is the delay for turning off the bidirectional shut-off valve connected to the i-th bridge arm. Duration, t _f + Δt ₁ <t _f + Δt ₂ , Δt ₃ is the on-time of the auxiliary valve. In Fig. 8, the period from the main branch current zero crossing to the closing of the auxiliary valve is the off time Δt of the thyristor valve _off , Δt _off must be greater than the minimum preset off time.

Step S1 is executed after the end of the control period in which t _f is located, and until the voltage of the hybrid converter topology is restored to stability, the bidirectional shut-off valve connected to the i-th thyristor valve is turned on, and the i-th thyristor valve is turned off. A thyristor valve is connected to the auxiliary valve, and step 1 is performed.

Step S1: Turn on the i-th thyristor valve, turn on the bidirectional shut-off valve connected to the i-th thyristor valve, turn off the auxiliary valve connected to the i-th thyristor valve, and perform step S2 after Δt.

Step S2: Turn off the bidirectional shut-off valve connected to the i-th thyristor valve, and turn on the auxiliary valve connected to the i-th thyristor valve. When the i-th thyristor valve is in the positive blocking state, step S3 is executed.

Step S3: Turn off the auxiliary valve connected to the i-th thyristor valve, and return to step S1 _{after Δt' off.}

Δt' _off is the length of time that the i-th thyristor valve is in the positive blocking state in a control cycle from step 1 to step 2, Δt ₁ is the delay time of turning on the auxiliary valve connected to the i-th thyristor valve, Δt ₂ Is the delay time for shutting off the bidirectional shut-off valve connected to the i-th thyristor valve, Δt is the conduction time of the bidirectional shut-off valve connected to the i-th thyristor valve,

T is a control period, Δt ₁ <Δt ₂ , i∈[1,6].

This application also provides another method for controlling the topology structure as described above. As shown in FIG. 9, the method includes:

Step T1: Turn on the i-th thyristor valve of the hybrid converter topology, turn on the bidirectional shut-off valve connected to the i-th thyristor valve, turn off the auxiliary valve connected to the i-th thyristor valve, and pass Δt After that, step T2 is executed,

Step T2: Turn off the bidirectional shut-off valve connected to the i-th thyristor valve, and turn on the auxiliary valve connected to the i-th thyristor valve. When the i-th thyristor valve is in a positive blocking state, step T3 is executed.

Step T3: Turn off the auxiliary valve connected to the i-th thyristor valve, after Δt″ _off , return to Step T1.

Δt″ _off is the length of time that the i-th thyristor valve is in the positive blocking state in a control cycle, Δt is the bidirectional shut-off valve connected to the i-th thyristor valve,

T is a control period, i∈[1,6].

In Figure 9, Sg1 is the control sequence of the thyristor valve, Sg12 is the control sequence of the shut-off valve, Sg13 is the control sequence of the auxiliary valve, Δt _on is the conduction time _{of the thyristor valve, and Δt″ off} is the forward resistance of the thyristor valve. The off time, the control period T is 2π, Δt is the on-time length of the shut-off valve,

Δt13 is the on-time of the auxiliary valve. The period from the zero current of the main branch circuit to the closing of the auxiliary valve is the off time Δt _off of the thyristor valve, and Δt _off must be greater than the minimum preset off time.

An AC-side controllable shut-off hybrid converter topology provided by an embodiment of the application includes three parallel branches, three bidirectional shut-off valves, and a converter transformer; each branch has a parallel thyristor valve A branch circuit and an auxiliary valve branch circuit; the thyristor valve branch circuit is composed of two thyristor valves connected in series, and the auxiliary valve branch circuit is composed of two series-connected thyristor valves with controllable shut-off of forward current and blocking capability of forward and reverse voltages. Auxiliary valve composition; the connection point between two series-connected thyristor valves is connected to one end of the two-way shut-off valve, and the other end of the two-way shut-off valve is connected to the connection point between the two series-connected auxiliary valves and the converter transformer The output terminal is connected; the hybrid converter topology provided by the embodiment of this application introduces a bidirectional shut-off valve on the AC side to ensure that the thyristor valve has enough reverse recovery time to reliably shut down, and at the same time, an auxiliary valve is used to assist the commutation The problem of commutation failure in the DC system is fundamentally solved; in this structure, the auxiliary valve can quickly transfer the phase current and flexibly control the commutation time area of the thyristor valve. After the commutation failure occurs, the valve current quickly transfers to the auxiliary valve and passes the full The high-current turn-off characteristics of the controlled device can quickly restore the commutation between the two bridge arms, which greatly accelerates the recovery time of the converter after the commutation fails; the bidirectional shut-off valve can shut off the valve side current in advance, and it is a thyristor at the same time The valve provides reverse voltage, which increases the area of the thyristor valve commutation time, and ensures the reliable shutdown of the thyristor valve. The two-way shut-off valve only needs to be arranged on each phase of the three-phase AC bus, and the number of series is less. The utilization rate is high, and the total loss generated is low; in addition, the structure can be put into use at any time auxiliary valve, which can effectively reduce the loss of thyristor valve, can achieve low voltage and low shut-off angle operation, and greatly reduce the inverter side Reactive power; in the first control method provided by the embodiments of this application, during normal operation, the auxiliary valve is not put into operation, but only needs to bear the voltage stress, and will not negatively affect the various operating conditions of the converter valve; Immediately after the failure or short-circuit fault occurs, the auxiliary valve is put into operation to realize the auxiliary commutation function in a short period of time, and quickly restore the commutation between multiple bridge arms. This technical solution makes full use of the advantages of thyristors and shut-off devices, introduces a two-way shut-off valve on the AC side, completes the transfer of the valve side current in advance, and the auxiliary valve is used to withstand large shut-off voltage stress in the event of a fault, without long-term Withstanding current stress, it does not increase device loss, improves the utilization of turn-off devices, facilitates engineering implementation, and reduces loss costs; the second control method provided by the embodiment of the application is a two-way shut-off valve connected to a thyristor valve Alternate operation mode with auxiliary valve, this operation mode can avoid the occurrence of failure failure or short circuit failure, which is beneficial to improve the overall reliability of the converter.

The embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, this application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, this application may use one or more computer-usable storage media containing computer-usable program codes, including but not limited to disk storage, compact disc read-only memory (CD-ROM), optical storage, etc. In the form of a computer program product implemented on it.

This application is described with reference to flowcharts and/or block diagrams of methods, equipment systems, and computer program products according to the embodiments of this application. Each process and/or block in the flowchart and/or block diagram, and the combination of processes and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions can be provided to the processors of general-purpose computers, special-purpose computers, embedded processors, or other programmable data processing equipment to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing equipment generate settings A device for realizing the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.

These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing equipment to work in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including the instruction device. The device implements the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.

These computer program instructions can also be loaded on a computer or other programmable data processing equipment, so that a series of operation steps are executed on the computer or other programmable equipment to produce computer-implemented processing, so as to execute on the computer or other programmable equipment. The instructions provide steps for implementing the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.

Claims (14)

1. A hybrid converter with controllable shutdown on the AC side, comprising: three parallel branches, three bidirectional shut-off valves and a converter transformer;

   Each branch is composed of parallel thyristor valve branch and auxiliary valve branch;

   The thyristor valve branch is composed of two series-connected thyristor valves, and the auxiliary valve branch is composed of two series-connected auxiliary valves with controllable shut-off of forward current and blocking capability of forward and reverse voltage;

   The connection point between the two series-connected thyristor valves is connected to one end of a two-way shut-off valve, and the other end of the two-way shut-off valve is respectively connected with the two series-connected forward current controllable shut-off valves. It is connected to the connection point between the auxiliary valve with forward and reverse voltage blocking capability and the output end of the converter transformer.
2. The inverter according to claim 1, wherein each thyristor valve is composed of a plurality of thyristors and a buffer component connected in series or in parallel with each thyristor.
3. The inverter of claim 1, wherein each auxiliary valve is composed of a plurality of first auxiliary sub-modules connected in series and each of the plurality of first auxiliary sub-modules connected in series. Composed of series or parallel buffer components;

   The first auxiliary sub-module is composed of a power module, or is composed of a power module and a diode connected in series with the power module;

   The power module is composed of a fully-controlled power electronic device with reverse voltage blocking capability, or is composed of a fully-controlled power electronic device without reverse voltage blocking capability and the same as the one that does not have reverse voltage blocking capability. The fully-controlled power electronic device is composed of anti-parallel diodes.
4. The inverter of claim 1, wherein each auxiliary valve is composed of an auxiliary timing control branch and a diode branch connected in series;

   The diode branch is composed of a plurality of diodes connected in series in the forward direction and a buffer component connected in series or in parallel with each of the diodes connected in series in the forward direction;

   The auxiliary timing control branch is composed of a plurality of power modules connected in series and a buffer component connected in series or in parallel with each of the power modules in series;

   The power module is composed of a fully-controlled power electronic device with reverse voltage blocking capability, or is composed of a fully-controlled power electronic device without reverse voltage blocking capability and the same as the one that does not have reverse voltage blocking capability. The fully-controlled power electronic device is composed of anti-parallel diodes.
5. The inverter of claim 1, wherein each auxiliary valve is composed of a plurality of first power electronic units connected in series;

   Each first power electronic unit is composed of a first auxiliary branch, a buffer component and a second auxiliary branch connected in parallel;

   Both the first auxiliary branch and the second auxiliary branch are composed of two sets of auxiliary timing control branches connected in series in a forward direction;

   Each group of auxiliary timing control branch is composed of a plurality of series-connected power modules and a buffer component connected in series or in parallel with each of the plurality of series-connected power modules;

   The power module is composed of a fully-controlled power electronic device with reverse voltage blocking capability, or is composed of a fully-controlled power electronic device without reverse voltage blocking capability and the same as the one that does not have reverse voltage blocking capability. The full control type power electronic device is composed of anti-parallel diodes;

   The connection points of the two groups of auxiliary sequential control branches of the first auxiliary branch and the connection points of the two groups of auxiliary sequential control branches of the second auxiliary branch are both external connection points of the auxiliary valve or the connection points of the auxiliary valve. The connection point of the other first power electronic unit in the auxiliary valve.
6. The inverter according to claim 1, wherein the auxiliary valve is composed of a plurality of second power electronic units connected in series;

   Each second power electronic unit is composed of a third auxiliary branch in parallel, an auxiliary timing control branch, a buffer component and a fourth auxiliary branch;

   Both the third auxiliary branch and the fourth auxiliary branch are composed of two groups of diode branches connected in series in a forward direction;

   Each group of diodes is composed of a plurality of diodes connected in series in the forward direction and a buffer component connected in series or in parallel with each of the diodes connected in series in the forward direction;

   The auxiliary timing control branch is composed of a plurality of power modules connected in series and a buffer component connected in series or in parallel with each of the power modules in series;

   The power module is composed of a fully-controlled power electronic device with reverse voltage blocking capability, or is composed of a fully-controlled power electronic device without reverse voltage blocking capability and the same as the one that does not have reverse voltage blocking capability. The full control type power electronic device is composed of anti-parallel diodes;

   The connection points of the two groups of diode branches of the third auxiliary branch and the connection points of the two groups of diode branches of the fourth auxiliary branch are both external connection points of the auxiliary valve or in the auxiliary valve Connection point for other second power electronic units.
7. The inverter according to claim 1, wherein each two-way shut-off valve is composed of a first two-way shut-off valve branch and a second two-way shut-off valve branch in reverse series with the first two-way shut-off valve branch. The branch circuit can be shut off valve;

   The first two-way shut-off valve branch and the second two-way shut-off valve branch are each composed of a plurality of second auxiliary sub-modules connected in series and a plurality of second auxiliary sub-modules connected in series respectively. Each second auxiliary sub-module is composed of buffer components connected in series or in parallel;

   The second auxiliary sub-module is composed of a fully-controlled power electronic device with reverse voltage blocking capability, or a fully-controlled power electronic device without reverse voltage blocking capability, and the same as the one that does not have reverse voltage blocking capability. The blocking capability full control type power electronic device is composed of a diode in reverse parallel connection and a buffer component connected in series or parallel with the full control type power electronic device without reverse voltage blocking capability.
8. The inverter according to claim 1, wherein each two-way shut-off valve is composed of a third two-way shut-off valve branch, a fifth auxiliary branch and a fourth two-way shut-off valve branch connected in parallel;

   The third two-way shut-off valve branch and the fourth two-way shut-off valve branch are both composed of two two-way shut-off valve timing control branches connected in series in a positive direction;

   Each two-way turn-off valve timing control branch is composed of multiple forward-series diodes and a buffer component connected in series or parallel with each forward-series diode;

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

   The second auxiliary sub-module is composed of a fully-controlled power electronic device with reverse voltage blocking capability, or a fully-controlled power electronic device without reverse voltage blocking capability, and the same as the one that does not have reverse voltage blocking capability. A full-control power electronic device with blocking capability is composed of a diode in anti-parallel connection and a buffer component connected in series or parallel with the full-control power electronic device without reverse voltage blocking capability;

   The external connection point of the third two-way shut-off valve branch is the connection point of the two diode timing control branches of the third two-way shut-off valve branch, and the fourth two-way shut-off valve branch The external connection point of is the connection point of the two diode timing control branches of the fourth bidirectional shut-off valve branch.
9. The inverter according to claim 1, wherein each two-way shut-off valve is composed of two fifth two-way shut-off valve branches connected in anti-parallel;

   Each fifth bidirectional shut-off valve branch is composed of a plurality of full-control power electronic devices connected in series in a forward direction and a buffer component connected in series or in parallel with each full-control power electronic device.
10. The inverter according to claim 1, wherein each bidirectional shut-off valve is composed of a plurality of power device modules connected in series;

    Each power device module is composed of two anti-parallel fully-controlled power electronic devices and a buffer component connected in series or in parallel with each fully-controlled power electronic device.
11. The inverter according to any one of claims 2-10, wherein the buffer component is composed of at least one of a capacitor, a resistance-capacitance circuit, a diode, an inductor, and a lightning arrester.
12. A control method of a hybrid converter with a controllable shutdown on the AC side includes:

    When the bidirectional shut-off valve connected to the i-th thyristor valve of the converter is in the on state, and the auxiliary valve connected to the i-th thyristor valve is in the off state, every other control The i-th thyristor valve is periodically turned on once; where i∈[1,6].
13. The method of claim 12, further comprising:

    At the time t _f detected that the i-th occurrence of the thyristor valve commutation failure or short-circuit failure, the time t _f + Δt ₁ is turned on and the i-th thyristor valve and the auxiliary valve connected to + t _f Turn off the bidirectional shut-off valve connected to the i-th thyristor valve at moment Δt _2;

    When the i-th thyristor valve is in a positive blocking state, turn off the auxiliary valve connected to the i-th thyristor valve;

    Repeat the following steps after the end of the control period in which t _f is located, until the inverter resumes normal operation, turns on the bidirectional shut-off valve connected to the i-th thyristor valve, and shuts off the connection with the i-th thyristor valve. Auxiliary valve connected with thyristor valve:

    Turn on the i-th thyristor valve, turn on the bidirectional shut-off valve connected to the i-th thyristor valve, and turn off the auxiliary valve connected to the i-th thyristor valve;

    After Δt, the bidirectional shut-off valve connected to the i-th thyristor valve is turned off, and the auxiliary valve connected to the i-th thyristor valve is turned on;

    When the i-th thyristor valve is in the positive blocking state, turn off the auxiliary valve connected to the i-th thyristor valve, and after Δt′ _off , return to perform the opening of the i-th thyristor valve , The step of turning on the bidirectional shut-off valve connected to the i-th thyristor valve, and shutting off the auxiliary valve connected to the i-th thyristor valve;

    Among them, Δt' _off is the length of time the i-th thyristor valve is in the positive blocking state in a control period, Δt ₁ is the delay time of turning on the auxiliary valve connected to the i-th thyristor valve, and Δt ₂ is The delay time for turning off the two-way shut-off valve connected to the i-th thyristor valve, Δt is the conduction time of the two-way shut-off valve connected to the i-th thyristor valve,

    

    T is a control period, Δt ₁ <Δt ₂ .
14. A control method of a hybrid converter with a controllable shutdown on the AC side includes:

    Turn on the i th thyristor valve of the converter, turn on the bidirectional shut-off valve connected to the i th thyristor valve, and turn off the auxiliary valve connected to the i th thyristor valve;

    After Δt, the bidirectional shut-off valve connected to the i-th thyristor valve is turned off, and the auxiliary valve connected to the i-th thyristor valve is turned on;

    When the i-th thyristor valve is in the positive blocking state, turn off the auxiliary valve connected to the i-th thyristor valve, and after Δt″ _off , return to perform the opening of the i-th thyristor valve , The step of turning on the bidirectional shut-off valve connected to the i-th thyristor valve, and shutting off the auxiliary valve connected to the i-th thyristor valve;

    Where Δt″ _off is the length of time the i-th thyristor valve is in the positive blocking state in one control period, and Δt is the on-time length of the bidirectional shut-off valve connected to the i-th thyristor valve,

    

    T is a control period, i∈[1,6].

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