CN214380681U

CN214380681U - Hybrid converter topology structure with controllable turn-off at alternating current side

Info

Publication number: CN214380681U
Application number: CN202120296023.7U
Authority: CN
Inventors: 张静; 汤广福; 欧阳文敏; 李婷婷; 王蒲瑞
Original assignee: Global Energy Interconnection Research Institute
Current assignee: Global Energy Interconnection Research Institute
Priority date: 2021-02-01
Filing date: 2021-02-01
Publication date: 2021-10-08
Anticipated expiration: 2031-02-01

Abstract

The utility model discloses a hybrid transverter topological structure of controllable shutoff of interchange side. Wherein, this topological structure includes: at least one phase conversion circuit, which comprises a thyristor valve branch and a first control valve or a second control valve branch which are connected in parallel; the thyristor branch is provided with a thyristor valve; the first control valve or the second control valve branch comprises a first control valve and a second control valve, and the first control valve and the second control valve both have a forward current controllable turn-off function and a forward and reverse voltage blocking function; the connecting end of the first control valve and the second control valve is connected with the output end of the converter transformer through a third control valve; the third control valve has a one-way voltage output controllable turn-off function; the connecting end of the series thyristor valve is connected with the output end of the converter transformer. Through implementing the utility model discloses, fundamentally has solved direct current system's commutation failure problem to electric wire netting operation's stability and security have been guaranteed.

Description

Hybrid converter topology structure with controllable turn-off at alternating current side

Technical Field

The utility model relates to a current conversion technical field among the power electronics, concretely relates to hybrid transverter topological structure that exchange side controllable turn-offs.

Background

The traditional power grid phase-change high voltage direct current (LCC-HVDC) power transmission system has the advantages of long-distance large-capacity power transmission, controllable active power and the like, and is widely applied in the world. The converter is used as core equipment of direct current transmission, is a core function unit for realizing alternating current and direct current electric energy conversion, and the operation reliability of the converter determines the operation reliability of an extra-high voltage direct current power grid to a great extent.

Because the traditional converter mostly adopts a thyristor of a semi-controlled device as a core component to form a six-pulse bridge conversion topology, each bridge arm is formed by serially connecting a multi-stage thyristor and a buffer component thereof, and the thyristor does not have self-turn-off capability, phase change failure is easy to occur under the conditions of AC system failure and the like, so that the direct current is increased rapidly, a large amount of direct current transmission power is lost rapidly, and the stable and safe operation of a power grid is influenced.

SUMMERY OF THE UTILITY MODEL

In view of this, the embodiment of the present invention provides a hybrid converter topology with controllable turn-off at ac side to solve the problem that the failure of commutation affects the stable and safe operation of the power grid.

According to a first aspect, the embodiment of the present invention provides a hybrid converter topology with controllable turn-off of ac side, the topology is connected to an ac grid through a converter transformer, the topology includes: at least one phase conversion circuit, which comprises a thyristor valve branch and a first control valve or a second control valve branch which are connected in parallel; a thyristor valve is arranged on the thyristor branch circuit; the first control valve or the second control valve branch comprises a first control valve and a second control valve, and the first control valve and the second control valve both have a forward current controllable turn-off function and a forward and reverse voltage blocking function; the connecting end of the first control valve and the second control valve is connected with the output end of the converter transformer through a third control valve; the third control valve has a one-way voltage output controllable turn-off function; and the connecting end of the thyristor valve is connected with the output end of the converter transformer.

With reference to the first aspect, in a first implementation of the first aspect, the topology includes: a three-phase current conversion circuit; the commutation circuits of the phases are arranged in parallel.

With reference to the first aspect, in a second embodiment of the first aspect, the third control valve includes: at least one first power cell, the at least one first power cell arranged in series; and the first buffer component is connected with the first power unit in parallel.

With reference to the second implementation manner of the first aspect, in a third implementation manner of the first aspect, the first power unit includes: the power supply comprises a first branch circuit, a second branch circuit and a control circuit, wherein the first branch circuit is provided with a first power device which is a fully-controlled power electronic device; and the second branch circuit is connected with the first branch circuit in parallel, a first capacitor element and the first power device are arranged on the second branch circuit, and the first power device and the first capacitor element are connected in series.

With reference to the second implementation manner of the first aspect, in a fourth implementation manner of the first aspect, the first power unit includes: the third branch circuit is a full-bridge circuit formed by connecting four second power devices; the second power device is a fully-controlled power electronic device; and the fourth branch is provided with a second capacitance element, and the second capacitance element is connected between the upper half bridge and the lower half bridge of the full-bridge circuit in parallel.

With reference to the first aspect, in a fifth embodiment of the first aspect, the first control valve and the second control valve have the same structure.

With reference to the fifth embodiment of the first aspect, in the third embodiment of the first aspect, the first control valve includes: at least one second power cell, the at least one second power cell arranged in series; and the second buffer component is connected with the second power unit in parallel.

With reference to the sixth implementation manner of the first aspect, in a seventh implementation manner of the first aspect, the second power unit includes: at least one fifth branch, the at least one fifth branch being arranged in series; a third power device and a first diode are arranged on the fifth branch, and the third power device is connected with the first diode in series; the third power device is a power electronic device without a reverse blocking function; or, a sixth branch, where at least one third power device is disposed on the sixth branch, and the at least one third power device is disposed in series; a seventh branch in series with the sixth branch; and at least one second diode is arranged on the seventh branch and is arranged in series.

With reference to the sixth implementation manner of the first aspect, in an eighth implementation manner of the first aspect, the second power unit includes: at least one eighth branch, the at least one eighth branch being arranged in series; the eighth branch circuit is a full-bridge circuit formed by connecting a plurality of fourth power devices; the fourth power device is a fully-controlled power electronic device.

With reference to the sixth implementation manner of the first aspect, in a ninth implementation manner of the first aspect, the second power unit includes: at least one ninth branch, which is arranged in series as an H-bridge circuit; the ninth branch comprises a first sub-branch, a second sub-branch and a third sub-branch; the first sub-branch is provided with a plurality of third diodes which are connected in series; the second sub-branch is connected in parallel between the first sub-branch and the third sub-branch, a plurality of fifth power devices connected in series are arranged on the second sub-branch, and the fifth power devices are full-control power electronic devices; and the third sub-branch is provided with a plurality of fourth diodes which are connected in series.

With reference to the first aspect, in a tenth implementation of the first aspect, the thyristor valve includes: at least one thyristor, the at least one thyristor arranged in series; and the third buffer component is connected with the thyristor in parallel or in series.

With reference to the second embodiment or the sixth embodiment or the tenth embodiment of the first aspect, in an eleventh embodiment of the first aspect, the first buffer member, the second buffer member and the third buffer member each include: the first buffer branch circuit consists of a capacitor; or, a second buffer branch circuit with a resistor and the capacitor connected in series; or, the capacitor and the resistor are connected in parallel by a third buffer branch; or the resistor is connected with the fifth diode in parallel and then connected with the capacitor in series to form a fourth buffer branch circuit; or, the resistor is connected in parallel with the capacitor and then connected in series with the fifth diode to form a fifth buffer branch circuit; or, a sixth buffering branch composed of the lightning arrester; or, a plurality of the first buffering branch, the second buffering branch, the third buffering branch, the fourth buffering branch, the fifth buffering branch and the sixth buffering branch are connected in parallel to form a seventh buffering branch.

The technical scheme of the utility model, have following advantage:

1. the embodiment of the utility model provides a controllable hybrid transverter topological structure who shuts off of interchange side, this topological structure includes at least one looks conversion circuit, and every looks conversion circuit includes parallelly connected thyristor valve branch road and auxiliary valve branch road, is provided with the thyristor valve on the thyristor branch road, and the auxiliary valve branch road includes first control valve and second control valve, and first control valve and second control valve all possess controllable shutoff function of forward current and positive and negative voltage blocking function; the connecting end of the first control valve and the second control valve is connected with the converter transformer through a third control valve; the third control valve has a one-way voltage output controllable turn-off function; the connecting end of the thyristor valve is connected with the converter transformer. According to the hybrid converter topological structure with the controllable turn-off at the alternating current side, the third control valve is arranged at the alternating current side, so that the thyristor valve is guaranteed to have enough reverse recovery time to be turned off reliably, and meanwhile, the problem of phase change failure of a direct current system is solved fundamentally by using the auxiliary valve branch, so that the stability and the safety of power grid operation are guaranteed.

2. The embodiment of the utility model provides a hybrid transverter topological structure of controllable shutoff of interchange side, auxiliary valve branch road can shift the phase current fast, the commutation time area of nimble control thyristor valve, when commutation failure or short-circuit fault, the electric current of thyristor branch road can shift to auxiliary valve branch road fast, through the electric current turn-off characteristic of auxiliary valve branch road, can resume commutation between two bridge arms fast to transverter recovery time when commutation failure or short-circuit fault has been accelerated.

3. The embodiment of the utility model provides a hybrid transverter topological structure of controllable shutoff of interchange side, the third control valve can turn off the electric current of thyristor branch road in advance, provides reverse voltage for the thyristor valve simultaneously, has increased thyristor valve commutation time area, has guaranteed the reliable shutoff of thyristor valve, and the third control valve only needs to arrange on each looks of three-phase alternating current generating line, and the series progression is less, has improved the utilization ratio of device, has reduced the total loss of device.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the technical solutions in the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a structural diagram of a hybrid converter topology with ac side controlled turn-off according to an embodiment of the present invention;

fig. 2 is a block diagram of a thyristor valve according to an embodiment of the present invention;

fig. 3 is a block diagram of a third control valve according to an embodiment of the present invention;

fig. 4 is another block diagram of a third control valve according to an embodiment of the present invention;

fig. 5 is a block diagram of a first/second control valve according to an embodiment of the present invention;

fig. 6 is a block diagram of a second power unit according to an embodiment of the present invention;

fig. 7 is another block diagram of the first/second control valve according to an embodiment of the present invention;

fig. 8 is another block diagram of the first/second control valve according to an embodiment of the present invention;

fig. 9 is a block diagram of a buffer member according to an embodiment of the present invention;

fig. 10 is a flow chart of a method of controlling a hybrid converter topology with ac side controlled turn-off according to an embodiment of the present invention;

fig. 11 is a current flow path according to an embodiment of the present invention in a normal operating state;

fig. 12 is a trigger control sequence according to an embodiment of the present invention;

fig. 13(a) is a current flow path through a thyristor branch to an auxiliary valve branch commutation stage according to an embodiment of the present invention;

fig. 13(b) is a current flow path of the thyristor branch turn-off auxiliary valve branch flow-through stage according to an embodiment of the present invention;

fig. 13(c) is a current flow path during the off phase of the thyristor branch and the auxiliary valve branch according to an embodiment of the present invention;

fig. 14 is a control timing sequence for each valve in which a commutation failure or short circuit fault is detected according to an embodiment of the present invention;

fig. 15 is another control method for a hybrid converter topology with ac side controlled turn-off according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by the skilled in the art without creative work belong to the protection scope of the present invention.

The converter is used as core equipment of direct current transmission, is a core function unit for realizing alternating current and direct current electric energy conversion, and the operation reliability of the converter determines the operation reliability of an extra-high voltage direct current power grid to a great extent. However, in the conventional converter, a thyristor which is a half-controlled device is mostly adopted as a core component to form a six-pulse bridge conversion topology, each bridge arm is formed by serially connecting a multi-stage thyristor and a buffer component thereof, and the thyristor does not have self-turn-off capability, so that phase change failure is easy to occur under the conditions of AC system faults and the like, so that the direct current is increased rapidly, a large amount of direct current transmission power is lost rapidly, and the stable and safe operation of a power grid is influenced.

Based on this, the utility model discloses technical scheme introduces the control valve that can turn-off in the interchange side, guarantees that thyristor valve has sufficient reverse recovery time in order to carry out reliable turn-off, utilizes the supplementary commutation of auxiliary valve branch road simultaneously, and fundamentally solves direct current system's commutation failure problem to the stable safe operation of electric wire netting has been guaranteed.

According to the embodiment of the utility model provides an exchange the controllable hybrid transverter topological structure's of turn-off of side embodiment, this exchange the controllable hybrid transverter topological structure who turns off of side and insert the AC electric network through converter transformer. As shown in fig. 1, the hybrid converter topology with controllable turn-off at ac side includes: and each phase commutation circuit comprises a thyristor branch and an auxiliary valve branch which are connected in parallel. The thyristor branch is provided with a thyristor valve, and as shown in fig. 1, V11, V21, V31, V41, V51 and V61 are thyristor valves; the auxiliary valve branch comprises a first control valve and a second control valve, and the first control valve and the second control valve both have a forward current controllable turn-off function and a forward and reverse voltage blocking function, as shown in fig. 1, V13, V33 and V53 are the first control valves, and V23, V43 and V63 are the second control valves respectively. Specifically, V11 and V41 are connected in series, V31 and V61 are connected in series, and V51 and V21 are connected in series, which are thyristor branches of each phase of the commutation circuit respectively; v13 and V43 are connected in series, V33 and V63 are connected in series, and V53 and V23 are connected in series, which are auxiliary valve branches in each phase conversion circuit respectively.

The connection ends of the first control valve and the second control valve are connected with the converter transformer through a third control valve, and the third control valve has a one-way voltage output controllable turn-off function, as shown in fig. 1, and V14, V36 and V52 are the third control valves. The connection ends of the V13 and the V43 are connected with the a-phase output end of the converter transformer through the V14; the connection ends of the V33 and the V63 are connected with the b-phase output end of the converter transformer through V36; the connection end of V53 and V23 is connected with the c-phase output end of the converter transformer through V52.

The connecting end of the thyristor valve on the thyristor branch is also connected with the output end of the converter transformer, so that a third control valve which can controllably turn off unidirectional voltage is introduced to the alternating current side. As shown in fig. 1, the connection terminals of V11 and V41 are connected to the a-phase output terminal of the converter transformer; the connection ends of the V31 and the V61 are connected with the b-phase output end of the converter transformer; and the connection ends of the V51 and the V21 are connected with the c-phase output end of the converter transformer.

The embodiment of the utility model provides a controllable hybrid transverter topological structure who shuts off of interchange side, including an at least looks conversion circuit, every looks conversion circuit includes parallelly connected thyristor valve branch road and auxiliary valve branch road, is provided with the thyristor valve on the thyristor branch road, and the auxiliary valve branch road includes first control valve and second control valve, and first control valve and second control valve all possess controllable shutoff function of forward current and forward and reverse voltage block function, and the link of first control valve and second control valve is connected with converter transformer through the third control valve; the third control valve has the function of one-way voltage output controllable shutoff, and the connecting end of the thyristor valve on the thyristor branch circuit is connected with the converter transformer. According to the topological structure of the hybrid converter, the third control valve is arranged on the alternating current side, so that the thyristor valve is guaranteed to have enough reverse recovery time to be reliably turned off, and meanwhile, the problem of phase commutation failure of a direct current system is fundamentally solved by utilizing the auxiliary valve branch, so that the stability and the safety of the operation of a power grid are guaranteed.

Optionally, the hybrid converter topology with controllable turn-off at the ac side includes three-phase converter circuits, and each of the three-phase converter circuits is connected in parallel. One end of the three-phase converter circuit connected in parallel is connected with the positive electrode of the direct current bus, and the other end is connected with the negative electrode of the direct current bus, as shown in fig. 1.

Optionally, the thyristor valve comprises at least one thyristor and a third buffer member connected in parallel or in series with the thyristor, respectively, wherein the at least one thyristor is arranged in series, and the first buffer member is used for the thyristor device to protect against high voltage and large current. As shown in fig. 2, the thyristor valve includes at least one thyristor and a third buffer member connected in parallel with the thyristors, respectively.

Optionally, taking the third control valve V14 as an example, the third control valve V14 includes at least one first power unit and first buffer components (parallel connection is known to those skilled in the art and not shown in the drawings) respectively connected in parallel with the first power unit, wherein the at least one first power unit is connected in series, and the second buffer component is used for limiting the voltage-current stress.

Specifically, as shown in fig. 3, the first power unit may be a power electronic unit composed of a first branch and a second branch.

A first power device is arranged on the first branch; the second branch circuit is connected with the first branch circuit in parallel, a first capacitor element and a first power device are arranged on the second branch circuit, and the first power device is connected with the first capacitor element in series. The first power device is a fully-controlled power electronic device, and the fully-controlled power electronic device is one or more of turn-off devices such as an IGBT, an IGCT, an IEGT, a GTO or a MOSFET. It should be noted that, if the fully-controlled power electronic device does not have the reverse voltage blocking function, a diode needs to be connected in parallel to the fully-controlled power electronic device in the reverse direction.

Specifically, as shown in fig. 4, the first power unit may also be a power electronic unit composed of a third branch and a fourth branch.

A full-bridge circuit is formed by connecting four second power devices of the third branch circuit; and a second capacitive element is arranged on the fourth branch and connected in parallel between the upper half bridge and the lower half bridge of the full-bridge circuit. The second power device is a fully-controlled power electronic device, and the fully-controlled power electronic device is one or more of an IGBT, an IGCT, an IEGT, a GTO or a MOSFET. It should be noted that, if the fully-controlled power electronic device does not have the reverse voltage blocking function, a diode needs to be connected in parallel to the fully-controlled power electronic device in the reverse direction.

The third control valve is a low-voltage full-control shutoff valve, has the capability of unidirectional voltage controllable output, is mainly used for shutting off the current of the thyristor branch circuit and providing reverse voltage for the thyristor branch circuit, and ensures that the thyristor valve of the thyristor branch circuit has enough shutoff time to carry out reliable shutoff. The topological form of the third control valve is not limited in the present application, and may be any topological form having a function of unidirectional voltage controllable output.

Optionally, the first control valve is identical in structure to the second control valve. Taking the first control valve V13 as an example, the first control valve V13 includes at least one second power unit and second buffer components respectively connected in parallel with the second power unit, wherein the at least one second power unit is connected in series, and the third buffer component is used for limiting voltage current stress.

Specifically, as shown in fig. 5, the second power unit may be a power electronic unit composed of at least one fifth branch, and the at least one fifth branch is arranged in series.

And a third power device and a first diode are arranged on the fifth branch, and the third power device and the first diode are arranged in series. The third power device is a fully-controlled power electronic device, and the fully-controlled power electronic device is one or more of an IGBT, an IGCT, an IEGT, a GTO or a MOSFET. It should be noted that, if the fully-controlled power electronic device does not have the reverse voltage blocking function, a diode needs to be connected in parallel to the fully-controlled power electronic device in the reverse direction to achieve the reverse voltage blocking function.

Specifically, as shown in fig. 6, the second power unit may also be a power electronic unit composed of a sixth branch and a seventh branch.

At least one third power device is arranged on the sixth branch, and the at least one third power device is arranged in series; the seventh branch circuit is connected in series with the sixth branch circuit, at least one second diode is arranged on the seventh branch circuit, and the at least one second diode is arranged in series. The third power device is a fully-controlled power electronic device, and the fully-controlled power electronic device is one or more of an IGBT, an IGCT, an IEGT, a GTO or a MOSFET. It should be noted that, if the fully-controlled power electronic device does not have the reverse voltage blocking function, a diode needs to be connected in parallel to the fully-controlled power electronic device in the reverse direction to achieve the reverse voltage blocking function.

Specifically, as shown in fig. 7, the second power unit may also be a power electronic unit composed of an eighth branch circuit. The eighth branch circuit is a full-bridge circuit formed by connecting a plurality of fourth power devices, wherein the fourth power devices are fully-controlled power electronic devices, and the fully-controlled power electronic devices are one or more of IGBTs, IGCTs, IEGTs, GTOs or MOSFETs. It should be noted that, if the fully-controlled power electronic device does not have the reverse voltage blocking function, a diode needs to be connected in parallel to the fully-controlled power electronic device in the reverse direction to achieve the reverse voltage blocking function.

The full-bridge circuit is sequentially connected in series to realize forward and reverse control of current, current transfer of the thyristor branch circuit to the auxiliary valve branch circuit is completed at any time, forward and reverse voltages are borne by the auxiliary valve branch circuit, each bridge arm in the full-bridge circuit is of a single-stage structure or a multi-stage series structure formed by a fully-controlled power electronic device and diodes in a matched mode, other topological forms can be certainly achieved, specific limitation is not needed, and a person skilled in the art can determine the current transfer according to actual needs.

Specifically, as shown in fig. 8, the second power unit may also be a power electronic unit composed of at least one ninth branch, and the at least one ninth branch is serially connected to form an H-bridge circuit.

The ninth branch includes: a first sub-branch, a second sub-branch and a third sub-branch. The first sub-branch is provided with a plurality of third diodes which are connected in series; the second sub-branch is connected in parallel between the first sub-branch and the third sub-branch, and a plurality of fifth power devices connected in series are arranged on the second sub-branch, wherein the fifth power device is a fully-controlled power electronic device, the fully-controlled power electronic device is one or more of an IGBT, an IGCT, an IEGT, a GTO or a MOSFET, and it should be noted that if the fully-controlled power electronic device does not have a reverse voltage blocking function, a diode needs to be connected in parallel in reverse on the fully-controlled power electronic device to realize the reverse voltage blocking function; and a plurality of fourth diodes connected in series are arranged on the third sub-branch. The fully-controlled power electronic device and the diode in the H-bridge circuit can be of a single-stage structure or a multi-stage series structure, and the H-bridge circuit is sequentially connected in series, so that the functions of bidirectional through-flow and bidirectional turn-off can be realized.

The first control valve and the second control valve are auxiliary valves and have forward current controllable turn-off and forward and reverse voltage blocking capabilities, the topological form of the first control valve and the second control valve is not limited, and the topological form can be used as long as the topological form has the functions of forward current controllable turn-off and forward and reverse voltage blocking.

Optionally, the first buffer component, the second buffer component and the third buffer component are all formed by one or more of a capacitor, a resistance-capacitance loop, a diode, an inductor or an arrester.

Specifically, as shown in fig. 9, the first buffer member, the second buffer member, and the third buffer member may be a first buffer branch composed of a capacitor; the second buffer branch can be formed by connecting a resistor and a capacitor in series; the third buffer branch can be formed by connecting a capacitor and a resistor in parallel; the fourth buffer branch RCD1 can be formed by connecting a resistor and a fifth diode in parallel and then connecting the resistor and a capacitor in series; a fifth buffer branch RCD2 formed by a resistor and a capacitor connected in parallel and then connected in series with a fifth diode; the sixth buffering branch circuit can also be composed of lightning arresters; the buffer circuit may also be a seventh buffer branch formed by connecting a plurality of the first buffer branch, the second buffer branch, the third buffer branch, the fourth buffer branch, the fifth buffer branch and the sixth buffer branch in parallel.

According to an embodiment of the present invention, there is provided an embodiment of a method for controlling a hybrid converter topology with ac-side controllable shutdown, it should be noted that the steps illustrated in the flowchart of the drawings may be executed in a computer system such as a set of computer executable instructions, and that although a logical order is illustrated in the flowchart, in some cases, the steps illustrated or described may be executed in an order different from the order illustrated herein.

In this embodiment, a method for controlling a hybrid converter topology with ac side controllable turn-off is provided, which can be used for the hybrid converter topology with ac side controllable turn-off described above, fig. 10 is a flow chart of forced commutation according to an embodiment of the present invention, as shown in fig. 10, the flow chart includes the following steps:

and S21, turning on the third control valve connected with the thyristor valve of the ith arm, and turning off the first control valve or the second control valve connected with the thyristor valve of the ith arm.

And S22, switching on the thyristor valve of the ith bridge arm.

And S23, after a control period, turning on the thyristor valve of the ith bridge arm, wherein i belongs to [1,6 ].

Specifically, as shown in fig. 11, the valve current flow path of the hybrid converter topology under normal operating conditions is provided, the thyristor branch periodically bears voltage and current stress, and the auxiliary valve branch is always in an off state and bears voltage stress only when the thyristor valve of the thyristor branch is turned off.

FIG. 12 shows the trigger control sequence of each valve under normal operating conditions, where Sg1 is the control sequence of the thyristor valve, Sg12 is the control sequence of the third control valve, Sg13 is the control sequence of the first control valve or the second control valve, t₀For the initial triggering moment, Δ t_onFor the conduction time of the thyristor valve, Δ t_offIs the turn-off time of the thyristor valve, delta t'_offThe control period T is 2 pi for the forward blocking time of the thyristor valve.

And when the phase commutation fails or a short-circuit fault occurs, triggering the forced phase commutation operation of the hybrid converter topological structure with the controllable turn-off of the alternating current side. The control method of the hybrid converter topology structure with the controllable turn-off alternating current side comprises the following steps: when detecting that the thyristor valve of the ith bridge arm has a phase change failure or a short-circuit fault, acquiring the duration of the phase change failure or the short-circuit fault; when the duration reaches a first preset duration, switching on a first control valve or a second control valve connected with the thyristor valve of the ith bridge arm, and when the duration reaches a second preset duration, switching off a third control valve connected with the thyristor valve of the ith bridge arm; the second preset time length is longer than the first preset time length; when the thyristor valve of the ith bridge arm is in a forward blocking state, the first control valve or the second control valve connected with the thyristor valve of the ith bridge arm is closed; when the phase change failure or the short-circuit fault is in the control period, switching on the thyristor valve of the ith bridge arm, switching on the third control valve connected with the thyristor valve of the ith bridge arm, and switching off the first control valve or the second control valve connected with the thyristor valve of the ith bridge arm; after a third preset time, turning off a third control valve connected with the thyristor valve of the ith bridge arm, and turning on the first control valve or the second control valve connected with the thyristor valve of the ith bridge arm; when the thyristor valve of the ith bridge arm is in a forward blocking state, a first control valve or a second control valve connected with the thyristor valve of the ith bridge arm is turned off, after a fourth preset time period, the thyristor valve of the ith bridge arm is turned on, a third control valve connected with the thyristor valve of the ith bridge arm is turned on, and a first control valve or a second control valve connected with the thyristor valve of the ith bridge arm is turned off; and when the voltage of the hybrid converter topology structure with the controllable turn-off alternating current side is recovered to be stable, turning on a third control valve connected with the thyristor valve of the ith bridge arm, turning off the first control valve or the second control valve connected with the thyristor valve of the ith bridge arm, and turning on the thyristor valve of the ith bridge arm.

Specifically, the first preset time period is a set time period for turning on the first control valve or the second control valve, the second preset time period is a set time period for turning off the third control valve, and the first preset time period and the second preset time period may be determined according to an attribute and an empirical value of an electronic device used, and are not specifically limited herein. The third preset time period is a conduction time period of the third control valve.

As shown in fig. 13(a), 13(b), 13(c) and 14, when t is reached_fWhen detecting that the ith thyristor valve has phase change failure or short circuit fault at the moment, at t_f+Δt₁Constantly conducting a first control valve or a second control valve connected with the ith thyristor valveAnd at t_f+Δt₂And the third control valve connected with the ith thyristor valve is closed at any time, and when the ith thyristor valve is in a positive blocking state, the first control valve or the second control valve connected with the ith thyristor valve is closed. Taking V11, V13 and V14 as examples, as shown in fig. 13(a), fig. 13(b) and fig. 13(c), the process is divided into three stages, fig. 13(a) shows a stage of commutation of the thyristor branch to the auxiliary valve branch, in which the V13 valve on the auxiliary valve branch is turned on after receiving a trigger signal, and then the V14 valve is turned off after receiving a signal, the commutation process of the thyristor branch to the auxiliary valve branch is completed; fig. 13(b) shows the thyristor branch off, auxiliary valve branch through-flow phase, in which the thyristor branch is completely off and current is completely diverted to the auxiliary valve branch; fig. 13(c) shows the shut-down phase of the thyristor branch and the auxiliary valve branch, in which the V13 valve of the auxiliary valve branch is shut down after receiving a shut-down signal, and at this time, the thyristor valve V11 is in a forward blocking state for receiving a forward voltage.

Wherein, Δ t₁Delay period of first or second control valve for turning on ith thyristor, delta t₂Delay period t for switching off the third control valve connected to the ith thyristor_f+Δt₁＜t_f+Δt₂。

FIG. 14 shows control timing of each valve when a commutation failure or a short-circuit failure is detected, Sg1 is control timing of the thyristor valve, Sg12 is control timing of the third control valve, Sg13 is control timing of the first control valve or the second control valve, t₁The control period T is 2 pi for the initial trigger time, and it is required to be explained that the time from the zero crossing of the thyristor branch current to the turn-off of the auxiliary valve branch is the turn-off time delta T of the thyristor valve_offHere,. DELTA.t_offGreater than the minimum preset off-time of the thyristor valve.

When t is_fAnd executing the step S1 after the control period is over until the voltage of the topological structure of the hybrid converter is recovered to be stable, turning on a third control valve connected with the ith thyristor valve, turning off the first control valve or the second control valve connected with the ith thyristor valve, and executing the turning on of the thyristor of the ith bridge armAnd (4) a valve step.

Step S1: turning on the ith thyristor valve, turning on a third control valve connected with the ith thyristor valve, turning off the first control valve or the second control valve connected with the ith thyristor valve, and executing step S2 after delta t;

step S2: turning off the third control valve connected to the ith thyristor valve, turning on the first control valve or the second control valve connected to the ith thyristor valve, and executing step S3 when the ith thyristor valve is in a forward blocking state;

step S3: turn off the first or second control valve connected to the ith thyristor valve by Δ t'_offThen, the process returns to step S1;

wherein, delta t'_offIs the time length of the ith thyristor valve in the positive blocking state in a control period, delta t₁Delay time period, Δ t, for switching on the first control valve or the second control valve connected to the ith thyristor valve₂A delay time period for turning off the third control valve connected to the ith thyristor valve, at is an on time period of the third control valve connected to the ith thyristor valve,

t is a control period, Δ T₁＜Δt₂，i∈[1,6]。

According to the control method of the topological structure of the hybrid converter with the controllable turn-off at the alternating current side, when the hybrid converter is in normal operation, the first control valve and the second control valve are not put into operation, and only voltage stress is born, so that negative effects on various operation conditions of the converter valve are avoided; and after a commutation failure fault or a short-circuit fault occurs, the first control valve or the second control valve is immediately switched in, so that an auxiliary commutation function is realized in a short time, and commutation between bridge arms is quickly recovered. The control method fully utilizes the advantages that the thyristor, the first control valve and the second control valve can be turned off, the third control valve is introduced into the alternating current side, the current transfer from the thyristor branch to the auxiliary valve branch is completed in advance, the first control valve and the second control valve bear larger turn-off voltage stress only when the phase change fails or short circuit faults occur, and the current stress does not need to be borne for a long time, so that the increase of device loss is avoided, the utilization rate of the device is improved, and the loss cost is reduced.

Based on the same utility model, the utility model discloses still provide another hybrid transverter topological structure's that exchange the controllable shutoff of side control method, as shown in fig. 15, the method includes:

step T1: conducting the ith thyristor valve of the hybrid converter topology, conducting a third control valve connected to the ith thyristor valve, switching off the first control valve and the second control valve connected to the ith thyristor valve, executing step T2 after delta T,

step T2: turning off the third control valve connected to the ith thyristor valve, turning on the first control valve and the second control valve connected to the ith thyristor valve, and executing the step T3 when the ith thyristor valve is in the forward blocking state;

step T3: the first control valve and the second control valve connected with the ith thyristor valve are closed, and the first control valve and the second control valve pass through delta t ″_offThen, returning to the step T1;

wherein, Δ t ″)_offThe time length of the ith thyristor valve in the forward blocking state in one control period, delta t is a third control valve connected with the ith thyristor valve,

t is a control period, i belongs to [1,6]]。

In fig. 15, Sg1 is a control timing of the thyristor valve, Sg12 is a control timing of the third control valve, Sg13 is a control timing of the first control valve and the second control valve, Δ t_onFor the conduction time of the thyristor valve, Δ t_offThe control period T is 2 pi for the forward blocking time of the thyristor valve, delta T is the conducting duration of the third control valve,

Δt₁₃the time from the zero crossing of the current of the thyristor branch to the turn-off of the auxiliary valve branch is the turn-off time delta t of the thyristor valve for the turn-on time of the first control valve and the second control valve_offHere,. DELTA.t_offGreater than the minimum preset off-time of the thyristor valve.

The embodiment of the utility model provides a control method of the controllable hybrid transverter topological structure who shuts off of interchange side connects thyristor valve, first control valve or the mode of second control valve operation in turn through the third control valve, has avoided the emergence of commutation failure or short-circuit fault, is favorable to improving the overall reliability of hybrid transverter.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope defined by the appended claims.

Claims

1. An alternating current side controlled turn-off hybrid converter topology for accessing an alternating current grid through a converter transformer, the topology comprising:

at least one phase conversion circuit, which comprises a thyristor valve branch and an auxiliary valve branch connected in parallel;

a thyristor valve is arranged on the thyristor branch circuit;

the auxiliary valve branch comprises a first control valve and a second control valve, and the first control valve and the second control valve have a forward current controllable turn-off function and a forward and reverse voltage blocking function;

the connecting end of the first control valve and the second control valve is connected with the output end of the converter transformer through a third control valve; the third control valve has a one-way voltage output controllable turn-off function;

and the connecting end of the thyristor valve is connected with the output end of the converter transformer.

2. The topology of claim 1, wherein the topology comprises:

a three-phase current conversion circuit; the commutation circuits of the phases are arranged in parallel.

3. The topology of claim 1, wherein the third control valve comprises:

at least one first power cell, the at least one first power cell arranged in series;

and the first buffer component is connected with the first power unit in parallel.

4. The topology of claim 3, wherein the first power unit comprises:

the power supply comprises a first branch circuit, a second branch circuit and a control circuit, wherein the first branch circuit is provided with a first power device which is a fully-controlled power electronic device;

and the second branch circuit is connected with the first branch circuit in parallel, a first capacitor element and the first power device are arranged on the second branch circuit, and the first power device and the first capacitor element are connected in series.

5. The topology of claim 3, wherein the first power unit comprises:

the third branch circuit is a full-bridge circuit formed by connecting four second power devices; the second power device is a fully-controlled power electronic device;

and the fourth branch is provided with a second capacitance element, and the second capacitance element is connected between the upper half bridge and the lower half bridge of the full-bridge circuit in parallel.

6. The topology of claim 1, wherein the first control valve and the second control valve are identical in structure.

7. The topology of claim 6, wherein the first control valve comprises:

at least one second power cell, the at least one second power cell arranged in series;

and the second buffer component is connected with the second power unit in parallel.

8. The topology of claim 7, wherein the second power cell comprises:

at least one fifth branch, the at least one fifth branch being arranged in series; a third power device and a first diode are arranged on the fifth branch, and the third power device is connected with the first diode in series; the third power device is a power electronic device without a reverse blocking function;

or the like, or, alternatively,

a sixth branch, on which at least one third power device is arranged, the at least one third power device being arranged in series;

a seventh branch in series with the sixth branch; and at least one second diode is arranged on the seventh branch and is arranged in series.

9. The topology of claim 7, wherein the second power cell comprises:

at least one eighth branch, the at least one eighth branch being arranged in series; the eighth branch circuit is a full-bridge circuit formed by connecting a plurality of fourth power devices; the fourth power device is a fully-controlled power electronic device.

10. The topology of claim 7, wherein the second power cell comprises:

at least one ninth branch, which is arranged in series as an H-bridge circuit;

the ninth branch comprises a first sub-branch, a second sub-branch and a third sub-branch;

the first sub-branch is provided with a plurality of third diodes which are connected in series;

the second sub-branch is connected in parallel between the first sub-branch and the third sub-branch, a plurality of fifth power devices connected in series are arranged on the second sub-branch, and the fifth power devices are full-control power electronic devices;

and the third sub-branch is provided with a plurality of fourth diodes which are connected in series.

11. The topology of claim 1, wherein the thyristor valve comprises:

at least one thyristor, the at least one thyristor arranged in series;

and the third buffer component is connected with the thyristor in parallel or in series.

12. The topology of claim 3, 7 or 11, wherein the first, second and third cushioning components each comprise:

the first buffer branch circuit consists of a capacitor;

or, a second buffer branch circuit with a resistor and the capacitor connected in series;

or, the capacitor and the resistor are connected in parallel by a third buffer branch;

or the resistor is connected with the fifth diode in parallel and then connected with the capacitor in series to form a fourth buffer branch circuit;

or, the resistor is connected in parallel with the capacitor and then connected in series with the fifth diode to form a fifth buffer branch circuit;

or, a sixth buffering branch composed of the lightning arrester;

or, a plurality of the first buffering branch, the second buffering branch, the third buffering branch, the fourth buffering branch, the fifth buffering branch and the sixth buffering branch are connected in parallel to form a seventh buffering branch.