Controllable current-source converter valve topology and control method therefor, device, and storage medium

Abstract

The present disclosure relates to the technical field of direct-current power transmission. Provided in the embodiments are a controllable current-source converter valve topology and a control method therefor, a device, and a storage medium. The controllable current-source converter valve topology comprises: a current-limiting reactor connected to the DC side of a turn-off six-pulse converter bridge, each bridge arm of the turn-off six-pulse converter bridge being connected to a reactor, the midpoint tap of each bridge arm of the turn-off six-pulse converter bridge leading out to form a three-phase output, and each output lead of the three-phase output being connected to a three-phase power grid by means of a respective first reactor; the three first reactors are respectively connected to three first switches in parallel; and a connection point of each three-phase output and the first reactor connected thereto is sequentially connected to a second reactor and a capacitor, each capacitor being connected to a second switch in parallel.

Description

Controllable current source type converter topology, control method, device and storage medium thereof

[0001] Cross-reference to related applications

[0002] The present disclosure claims priority to the Chinese patent application No. 202410475934.4, filed on April 19, 2024, entitled "Controllable current source type converter topology and control method thereof", the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the technical field of direct current transmission, in particular to a controllable current source type converter topology, a control method, a device and a storage medium thereof. BACKGROUND

[0004] High-voltage direct current transmission technology is a key technology for long-distance power transmission, and there are currently two technical routes: conventional direct current and flexible direct current. Conventional direct current relies on AC grid commutation, and the problem of multi-infeed direct current commutation failure is increasingly prominent. With the access of multi-drop direct current in developed areas, the risk of large-area cascading commutation failure will challenge the short-circuit capacity of the system, so the application range of this technology will not be able to expand.

[0005] Although the flexible direct current transmission technology does not have the problem of commutation failure, and has the characteristics of flexible and controllable power, it can also operate in network, and the voltage polarity does not need to follow when the power is reversed, but the device cost is high, the loss is large, and the capacity is insufficient.

[0006] SUMMARY

[0007] In order to overcome the above defects, the present application provides a controllable current source type converter topology, a control method, a device and a storage medium thereof.

[0008] In a first aspect, a controllable current source type converter topology is provided, comprising:

[0009] A current-limiting reactor connected to the DC side of the turn-off six-pulse converter bridge, an electric reactor is connected to each bridge arm of the turn-off six-pulse converter bridge, and a three-phase outlet is formed by the middle tap of each bridge arm of the turn-off six-pulse converter bridge. Each outlet of the three-phase outlet is connected to a three-phase power grid through three first electric reactors respectively; the three first electric reactors are connected in parallel with three first switches respectively; the junction between each three-phase outlet and the first electric reactor connected thereto is connected with a second electric reactor and a capacitor in sequence, and each capacitor is connected in parallel with a second switch.

[0010] Preferably, the turn-off six-pulse converter bridge comprises a first branch, a second branch and a third branch connected in parallel with each other.

[0011] The first branch comprises a first turn-off device topology and a second turn-off device topology connected in series;

[0012] The second branch comprises a third turn-off device topology and a fourth turn-off device topology connected in series;

[0013] The third branch comprises a fifth turn-off device topology and a sixth turn-off device topology connected in series.

[0014] Preferably, the turn-off device topology comprises a main branch and an auxiliary branch connected in parallel;

[0015] The main branch comprises a saturable reactor, a thyristor and an H-bridge structure connected in series;

[0016] The auxiliary branch comprises an IGBT and a thyristor connected in series.

[0017] Further, the H-bridge structure comprises a first IGBT, a second IGBT, a third IGBT and a fourth IGBT;

[0018] The series connection of the first IGBT and the second IGBT and the series connection of the third IGBT and the fourth IGBT are connected in parallel, and a capacitor is connected between the connection points of the first IGBT and the second IGBT and the connection points of the third IGBT and the fourth IGBT.

[0019] Further, the thyristor in the main branch is multiple, and the IGBT and the thyristor in the auxiliary branch are multiple.

[0020] Further, the configuration ratio of the number of reactors connected on the bridge arm of the turn-off six-pulse converter bridge to the number of thyristors contained in the turn-off device topology connected on the bridge arm of the turn-off six-pulse converter bridge is 2:x, wherein x is any value between 8 and 13.

[0021] Further, the turn-off device topology further comprises an arrester connected in parallel with the main branch and the auxiliary branch.

[0022] In a second aspect, a control method based on a controllable current source type converter valve topology is provided, and the method comprises:

[0023] Taking the voltage zero point of the capacitor as the initial time of timing, the turn-off six-pulse converter bridge is switched between bridge arms by triggering angle;

[0024] When the auxiliary branch current in the controllable current source type converter valve topology of the turn-off device topology structure reaches the maximum, the auxiliary branch in the turn-off device topology structure is commutated to the main branch; and when the auxiliary branch current in the controllable current source type converter valve topology of the turn-off device topology structure is zero, the main branch in the turn-off device topology structure is commutated to the auxiliary branch.

[0025] Preferably, the bridge arm commutation of the turn-off six-pulse commutation bridge comprises:

[0026] When the first turn-off device topology structure and the third turn-off device topology structure of the controllable current source type converter valve topology are subjected to bridge arm commutation, the thyristor of the main branch in the first turn-off device topology structure and the first IGBT and the fourth IGBT of the H-bridge structure are closed, the IGBT and the thyristor of the auxiliary branch in the first turn-off device topology structure are closed, the IGBT and the thyristor of the auxiliary branch in the third turn-off device topology structure are closed, the second IGBT and the third IGBT of the H-bridge structure of the main branch in the first turn-off device topology structure are opened, and all the IGBTs of the H-bridge structure of the main branch in the third turn-off device topology structure are opened.

[0027] Preferably, the commutation of the main branch in the turn-off device topology structure to the auxiliary branch comprises:

[0028] The IGBT and the thyristor of the auxiliary branch in the turn-off device topology structure are closed, the first IGBT and the fourth IGBT of the H-bridge structure of the main branch in the turn-off device topology structure are opened, and the main branch thyristor is opened after the current transfer is completed.

[0029] Preferably, the commutation of the auxiliary branch in the turn-off device topology structure to the main branch comprises:

[0030] The thyristor of the main branch in the turn-off device topology structure and the second IGBT and the third IGBT of the H-bridge structure are closed, all the IGBTs and the thyristor of the auxiliary branch are closed, and the auxiliary branch IGBT and the thyristor are opened after the current transfer is completed.

[0031] In a third aspect, an electronic device is provided, and the electronic device comprises the controllable current source type converter valve topology according to any one of the first aspect.

[0032] In a fourth aspect, a computer readable storage medium is provided, and the storage medium stores a computer program, and the computer program is used to execute the method according to any one of the second aspect.

[0033] The one or more technical solutions of the present application have at least one or more of the following beneficial effects:

[0034] The application provides a controllable current source type converter topology and a control method, device and storage medium thereof, and relates to the technical field of power electronic. BRIEF DESCRIPTION OF DRAWINGS

[0035] Fig. 1 is a main structure block diagram of the controllable current source type converter topology of the embodiment of the application.

[0036] Fig. 2 is a main structure block diagram of the controllable current source type converter topology of the embodiment of the application.

[0037] Fig. 3 is a bridge arm commutation process diagram of the controllable current source type converter topology of the embodiment of the application. DETAILED DESCRIPTION

[0038] The specific embodiments of the application will be further described in detail below with reference to the accompanying drawings.

[0039] In order to make the purpose, technical scheme and advantages of the embodiments of the application clearer, the technical scheme of the embodiments of the application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0040] As disclosed in the background art, high-voltage direct current transmission technology is a key technology for long-distance power transmission, and there are two technical routes of conventional direct current and flexible direct current at present. The conventional direct current relies on AC grid commutation, and the problem of multi-infeed direct current commutation failure is increasingly prominent. With the access of multi-drop direct current in developed areas, the risk of large-area cascading commutation failure will challenge the short-circuit capacity of the system, so the application range of the technology will not be able to expand.

[0041] Although the flexible direct current transmission technology does not have the problem of commutation failure and has the characteristics of flexible and controllable power, it can also operate in network, and the voltage polarity does not need to follow when the power is reversed, but the device cost is high, the loss is large, and the capacity is insufficient.

[0042] To improve the above-mentioned problems, the present invention provides a controllable current source type converter valve topology and its control method, including: a current-limiting reactor connected to the DC side of a six-pulse converter bridge that can be shut off, a reactor connected to each bridge arm of the six-pulse converter bridge, a middle tap outlet of each bridge arm of the six-pulse converter bridge forming a three-phase outlet, each outlet connection of the three-phase outlet respectively passing through three first reactors and then connected to the three-phase power grid; three first switches are connected in parallel to the three first reactors; the connection between each three-phase outlet and the first reactor connected to it is connected in sequence to a second reactor and a capacitor, and each capacitor is connected in parallel to a second switch. The components used in the circuit topology provided by the present invention are only controllable devices, passive components such as capacitors and inductors, etc., and the implementation technology is relatively flexible, simple and easy to implement, and flexible to control.

[0043] The above scheme is described in detail below.

[0044] Example 1

[0045] 1 , which is a main structural block diagram of a controllable current source type converter valve topology according to an embodiment of the present invention.

[0046] As shown in FIG1 , the controllable current source type converter valve topology in the embodiment of the present invention mainly includes:

[0047] The current-limiting reactor L connected to the DC side of the turn-off six-pulse commutation bridge dc Each arm of the switchable six-pulse commutation bridge is connected to a reactor L bt The middle tapped outgoing line of each bridge arm of the shut-off six-pulse commutation bridge forms a three-phase outlet. Each outlet connection of the three-phase outlet is connected to the three-phase grid after passing through three first reactors L. The three first reactors L are respectively connected in parallel with three first switches K1. The connection between each three-phase outlet and the first reactor L connected to it is connected in sequence to a second reactor L. ct and a capacitor C1, each capacitor is connected in parallel with a second switch K2.

[0048] In this embodiment, as shown in FIG2 , the shut-down six-pulse commutation bridge includes: a first branch, a second branch, and a third branch connected in parallel;

[0049] The first branch includes a first turn-off device topology structure and a second turn-off device topology structure connected in series;

[0050] The second branch includes a third turn-off device topology structure and a fourth turn-off device topology structure connected in series;

[0051] The third branch includes a fifth turn-off device topology structure and a sixth turn-off device topology structure connected in series.

[0052] Preferably, the turn-off device topology comprises a main branch and an auxiliary branch in parallel with each other.

[0053] The main branch comprises a saturable reactor, a thyristor and an H-bridge structure connected in series.

[0054] The auxiliary branch comprises an IGBT and a thyristor connected in series.

[0055] In one embodiment, the H-bridge structure comprises a first IGBT, a second IGBT, a third IGBT and a fourth IGBT.

[0056] The series connection of the first IGBT and the second IGBT and the series connection of the third IGBT and the fourth IGBT are in parallel, and a capacitor C2 is connected between the connection point between the first IGBT and the second IGBT and the connection point between the third IGBT and the fourth IGBT.

[0057] In one embodiment, the thyristor in the main branch is multiple, and the IGBT and the thyristor in the auxiliary branch are multiple.

[0058] In one embodiment, the configuration ratio of the number of reactors connected on the bridge arm of the controllable current source type converter valve to the number of thyristors contained in the turn-off device topology connected on the bridge arm of the controllable current source type converter valve is 2:x, wherein x is any value between 8 and 13.

[0059] In one embodiment, the turn-off device topology further comprises an arrester in parallel with the main branch and the auxiliary branch.

[0060] The controllable current source type converter valve designed by the application has a main branch opening process using the voltage difference of the parallel branch, so the main branch opens at low voltage, and the auxiliary branch is in an open state during the turn-off process, so the auxiliary branch is turned off at zero current. Since the device uses a thyristor or an IGBT, the device has large capacity and low loss.

[0061] The controllable current source type converter valve designed by the application adopts a bridge arm mixed topology. Since the main current branch uses a thyristor and the auxiliary branch uses an IGBT, the two branches are mixed in parallel, so the device has large current current and turn-off capacity.

[0062] Example 2

[0063] The application also provides a control method based on the controllable current source type converter valve topology. Specifically, the current I dThe current flows as shown in FIG. 3. In normal conduction, the current flows through the thyristors of the main branch of the Sl main branch and the full-bridge module, bearing the rated current and overload current; in commutation, the voltage zero point of the capacitor is taken as the initial time point, and the first controllable current source type converter topology Sl and the third controllable current source type converter topology S3 are commutated between the bridge arms through the firing angle.

[0064] For example, the first controllable current source type converter topology Sl and the third controllable current source type converter topology S3 are commutated between the bridge arms through the firing angle.

[0065] When the auxiliary branch current of the controllable current source type converter topology reaches the maximum, the auxiliary branch of the controllable current source type converter topology is commutated to the main branch, and when the auxiliary branch current of the controllable current source type converter topology is zero, the main branch of the controllable current source type converter topology is commutated to the auxiliary branch.

[0066] In this embodiment, the first controllable current source type converter topology and the third controllable current source type converter topology are commutated between the bridge arms, including:

[0067] The thyristors of the main branch of the first controllable current source type converter topology, the first IGBT and the fourth IGBT of the H-bridge structure, the IGBT and the thyristor of the auxiliary branch of the first controllable current source type converter topology, the IGBT and the thyristor of the auxiliary branch of the third controllable current source type converter topology are closed, the second IGBT and the third IGBT of the H-bridge structure of the main branch of the first controllable current source type converter topology are opened, and all IGBTs of the H-bridge structure of the main branch of the third controllable current source type converter topology are opened.

[0068] In this embodiment, the main branch of the controllable current source type converter topology is commutated to the auxiliary branch, including:

[0069] The IGBT and the thyristor of the auxiliary branch of the controllable current source type converter topology are closed, the first IGBT and the fourth IGBT of the H-bridge structure of the main branch of the controllable current source type converter topology are opened, and the main branch thyristor is opened after the current transfer is completed.

[0070] In this embodiment, the auxiliary branch of the controllable current source type converter topology is commutated to the main branch, including:

[0071] The thyristors of the main branch of the controllable current source type converter topology and the second IGBT and the third IGBT of the H-bridge structure are closed, all IGBTs and thyristors of the auxiliary branch are closed, and the auxiliary branch IGBT and the thyristor are opened after the current transfer is completed.

[0072] The zero point can be obtained by a software phase-locked loop calculation and a hardware zero point acquisition method, and the calculation method of the trigger angle mainly comprises the following steps: according to the amplitude of active power and reactive power of the system, in combination with the amplitude and phase of the alternating voltage, the amplitude and phase angle difference of the capacitor voltage are calculated, and then the time of opening of the bridge arm is obtained according to the phase angle difference, that is, the delay time of opening of the bridge arm; the time width of opening of the bridge arm is controlled, so as to control the current injected from the direct current side to the alternating current side, and then the current flowing into the capacitor and the current of the alternating current system are controlled, so as to control the charging voltage of the capacitor.

[0073] The topology of the present application mainly depends on the active and reactive regulation, which can realize commutation at any time, and the commutation voltage is defined as two specific processes according to the commutation voltage at the active commutation time: positive voltage commutation: the voltage of the off bridge arm is greater than the voltage of the on bridge arm, and the trigger angle is less than 0; negative voltage commutation: the voltage of the off bridge arm is less than the voltage of the on bridge arm, and the trigger angle is greater than 0. As shown in Figure 3. The two commutation processes mean that the converter can work in the leading angle or the lagging angle, indicating that the converter can emit and absorb reactive power.

[0074] The controllable current source type converter valve topology of the embodiment of the present application completely eliminates the influence of the converter leakage reactance on the commutation process, and the converter working process has no commutation angle, so that the consumption of system reactive power is greatly reduced; the nonlinear element lightning arrester does not participate in the commutation process, the voltage distribution difficulty of different elements of the auxiliary branch of the converter valve is reduced, and the structure of the auxiliary branch is simplified.

[0075] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can adopt a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer usable storage media containing computer usable program code (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.).

[0076] The present application is described with reference to flowcharts and / or block diagrams of the method, device (system), and computer program product according to the embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows 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 processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device for implementing the functions specified in one or more flows of the flowchart and / or one or more blocks of the block diagram.

[0077] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart or flowsheets and / or block or blocks of the block diagrams.

[0078] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart or flowsheets and / or block or blocks of the block diagrams.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application rather than limit it, and although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the specific embodiments of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and any modification or equivalent replacement without departing from the spirit and scope of the present application should be covered in the protection scope of the claims of the present application. Industrial applicability

[0080] The embodiment of the present disclosure provides a controllable current source type converter topology and a control method, device and storage medium thereof, and relates to the technical field of direct current transmission, and comprises: a current limiting reactor connected with a direct current side of a turn-off six-pulse converter bridge, an electric reactor is connected to each bridge arm of the turn-off six-pulse converter bridge, a middle tap output line of each bridge arm of the turn-off six-pulse converter bridge forms a three-phase outlet, and each outlet line of the three-phase outlet is connected to a three-phase power grid through three first electric reactors respectively; the three first electric reactors are connected in parallel with three first switches respectively; the junction between each three-phase outlet and the first electric reactor connected thereto is connected with a second electric reactor and a capacitor in sequence, and each capacitor is connected in parallel with a second switch. The circuit topology provided by the present application only uses controllable devices, passive elements such as capacitors and inductors, and the implementation technology is relatively flexible, simple and easy to control.

Claims

1. A controllable current source converter topology, the controllable current source converter topology comprising: The current limiting reactor is connected to the DC side of the turn-off six-pulse converter bridge, each bridge arm of the turn-off six-pulse converter bridge is connected with a reactor, and the middle tap of each bridge arm of the turn-off six-pulse converter bridge is connected with a three-phase outlet, each outlet of the three-phase outlet is connected to a three-phase power grid through a first reactor and a first switch in parallel.

2. The controllable current source type converter topology of claim 1, wherein, The turn-off six-pulse converter bridge comprises a first branch, a second branch and a third branch in parallel with each other. The first branch comprises a first turn-off device topology and a second turn-off device topology connected in series. The second branch comprises a third turn-off device topology and a fourth turn-off device topology connected in series. The third branch comprises a fifth turn-off device topology and a sixth turn-off device topology connected in series.

3. The controllable current source thyristor topology of claim 1, wherein, The turn-off device topology comprises a main branch and an auxiliary branch in parallel with each other. The main branch comprises a saturable reactor, a thyristor and an H-bridge structure connected in series. The auxiliary branch comprises an IGBT and a thyristor connected in series.

4. The controllable current source thyristor topology of claim 3, wherein, The H-bridge structure comprises a first IGBT, a second IGBT, a third IGBT and a fourth IGBT. The series connection of the first IGBT and the second IGBT and the series connection of the third IGBT and the fourth IGBT are connected in parallel, and a capacitor is connected between the connection point between the first IGBT and the second IGBT and the connection point between the third IGBT and the fourth IGBT.

5. Controllable current source type thyristor topology according to claim 4, wherein, The main branch comprises a plurality of thyristors, and the auxiliary branch comprises a plurality of IGBTs and thyristors.

6. Controllable current source type thyristor topology according to claim 5, wherein, The number of reactors connected to the bridge arm of the turn-off six-pulse converter bridge and the number of thyristors contained in the turn-off device topology connected to the bridge arm of the turn-off six-pulse converter bridge are in a configuration ratio of 2:x, wherein x is any value between 8 and 13.

7. A controllable current source thyristor topology according to claim 3, wherein, The turn-off device topology further comprises an arrester connected in parallel with the main branch and the auxiliary branch.

8. A control method of the controllable current source type converter valve topology according to any one of claims 4-7, the method comprising: taking the voltage zero point of the capacitor as the initial time of the timing, and switching between the bridge arms of the turn-off six-pulse converter bridge by triggering angle; wherein when the auxiliary branch current of the turn-off device topology of the controllable current source type converter valve topology reaches the maximum, the auxiliary branch of the turn-off device topology is switched to the main branch, and when the auxiliary branch current of the turn-off device topology of the controllable current source type converter valve topology is zero, the main branch of the turn-off device topology is switched to the auxiliary branch.

9. The method of claim 8, wherein, The switching between the bridge arms of the turn-off six-pulse converter bridge comprises: When the first controllable current source type converter topology and the third controllable current source type converter topology are switched between the bridge arms, the thyristor of the main branch in the first controllable current source type converter topology and the first IGBT and the fourth IGBT of the H-bridge structure are closed, the IGBT and the thyristor of the auxiliary branch in the first controllable current source type converter topology are closed, the IGBT and the thyristor of the auxiliary branch in the third controllable current source type converter topology are closed, the second IGBT and the third IGBT of the H-bridge structure of the main branch in the first controllable current source type converter topology are opened, and all the IGBTs of the H-bridge structure of the main branch in the third controllable current source type converter topology are opened.

10. The method of claim 8, wherein, The switching of the main branch to the auxiliary branch in the controllable current source type converter topology comprises: the IGBT and the thyristor of the auxiliary branch in the controllable current source type converter topology are closed, the first IGBT and the fourth IGBT of the H-bridge structure of the main branch in the controllable current source type converter topology are opened, and the main branch thyristor is opened after the current transfer is completed.

11. The method of claim 8, wherein, The switching of the auxiliary branch to the main branch in the controllable current source type converter topology comprises: the thyristor of the main branch in the controllable current source type converter topology and the second IGBT and the third IGBT of the H-bridge structure are closed, all the IGBTs and the thyristor of the auxiliary branch are closed, and the auxiliary branch IGBT and the thyristor are opened after the current transfer is completed.

12. An electronic device comprising the controllable current source type converter topology according to any one of claims 1 to 7.

13. A computer readable storage medium, the storage medium storing a computer program for executing the method according to any one of claims 8 to 11.

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