CN116154747A - Modularized multi-level voltage regulating device for DC power transmission system transformer, control method and control system - Google Patents
Modularized multi-level voltage regulating device for DC power transmission system transformer, control method and control system Download PDFInfo
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- CN116154747A CN116154747A CN202111395365.5A CN202111395365A CN116154747A CN 116154747 A CN116154747 A CN 116154747A CN 202111395365 A CN202111395365 A CN 202111395365A CN 116154747 A CN116154747 A CN 116154747A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
- H02J1/08—Three-wire systems; Systems having more than three wires
- H02J1/082—Plural DC voltage, e.g. DC supply voltage with at least two different DC voltage levels
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
- H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
- H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
- H02J9/061—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for DC powered loads
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
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Abstract
The invention discloses a modularized multi-level voltage regulating device of a direct current transmission system transformer, a control method and a control system. The device comprises a connecting switch, a connecting transformer, a voltage regulating transformer, a connecting valve and a pressure regulating valve; the pressure regulating valve and the connecting valve are both H-bridge structures consisting of bridge arms, the direct current side of the pressure regulating valve is connected with the direct current side of the connecting valve in parallel, two midpoints of the H-bridge of the pressure regulating valve are connected to primary windings of the pressure regulating transformer, secondary windings of the pressure regulating transformer are connected between the low voltage side of the primary windings of the direct current transmission system transformer and the ground in series, the two midpoints of the H-bridge of the connecting valve are connected to the primary windings of the connecting transformer, and the secondary windings of the connecting transformer are connected with the connecting switch in series and then connected to a certain alternating current bus of the converter station in parallel. The invention can replace the traditional on-load tap-changer of the mechanical transformer, avoid frequent occurrence of faults of the tap-changer of the direct current transmission project, and lighten the pressure of long-term reliable operation of the ultra-high voltage project.
Description
Technical Field
The invention belongs to the technical field of direct current transmission, and particularly relates to a voltage regulating technology of a transformer of a direct current transmission system.
Background
The scale of renewable energy source utilization is continuously enlarged, particularly solar energy, wind energy and the like, and as the transmission distance is long, the transmission of electricity through a conventional long-distance alternating current power grid can cause larger capacitance current, so that the transmission capacity receives larger challenges, and the direct current transmission technology is widely applied. The direct-current transmission converter transformer is used as one of main equipment for adjusting voltage and improving voltage quality, and the on-load tap changer of the converter transformer shown in fig. 1 is one of important parts of the direct-current transmission converter transformer, and the on-load tap changer of the converter transformer can realize the effects of maintaining direct-current voltage, compensating voltage fluctuation, optimizing reactive power characteristics and the like in direct-current transmission.
However, the traditional mechanical on-load voltage regulating switch has high fault rate and high maintenance cost because the contacts generate electric arcs in the switching process. Compared with a power transformer of an alternating current power grid, the electric quantity of the valve side of the direct current transmission converter transformer generally contains harmonic waves caused by phase change or inconsistent triggering angles, so that the contacts of the on-load tap-changer bear higher voltage change rate in the switching process, and bear complex stress combined actions such as electricity, heat, force, vibration and the like for a long time in operation, and the operation working condition is very severe. The tap switch of the existing direct current transmission project frequently has faults, and brings huge pressure to the long-term reliable operation of the ultra-high and extra-high voltage projects.
Disclosure of Invention
In order to solve the technical problems mentioned in the background art, the invention provides a modularized multi-level voltage regulating device, a control method and a control system of a transformer of a direct current transmission system, solves the problem of frequent occurrence of tap switch faults of the direct current transmission project, and reduces the pressure of long-term reliable operation of ultra-high voltage projects.
In order to achieve the technical purpose, the technical scheme of the invention is as follows:
the modularized multi-level voltage regulating device of the direct current transmission system transformer comprises a connecting switch, a connecting transformer, a voltage regulating transformer, a connecting valve and a pressure regulating valve; the pressure regulating valve and the connecting valve are H-bridge structures formed by bridge arms;
the direct current side of the pressure regulating valve is connected with the direct current side of the connecting valve in parallel, and two midpoints of an H bridge of the pressure regulating valve are connected to a primary winding of the pressure regulating transformer;
the secondary winding of the voltage regulating transformer is connected in series between the low-voltage side of the primary winding of the DC transmission system transformer and the ground;
two midpoints of the H bridge of the connecting valve are connected to a primary winding of the connecting transformer, and a secondary winding of the connecting transformer is connected in series with the connecting switch and then connected in parallel to a certain alternating current bus of the converter station.
Further, the bridge arm is formed by connecting a bridge arm valve and a reactor in series, and the bridge arm valve comprises a submodule or is formed by cascading a plurality of submodules.
Further, the submodule at least comprises two switching devices, a capacitor, a resistor and a bypass switch, wherein the two switching devices are connected in series and then connected in parallel with the capacitor and the resistor, and the bypass switch is connected in parallel with one of the switching devices.
Further, the submodule at least comprises four switching devices, a capacitor, a resistor and a bypass switch, wherein the four switching devices form a full-bridge circuit, the full-bridge circuit is connected with the capacitor and the resistor in parallel, and the bypass switch is connected with two midpoints of the full-bridge circuit in parallel.
Further, the transformer further comprises a voltage regulating side bypass switch, wherein the voltage regulating side bypass switch is connected in parallel to two ends of a secondary winding of the voltage regulating transformer.
Further, the voltage regulating side bypass switch is a fast mechanical switch or a power electronic switch.
A control method of a modularized multi-level voltage regulating device of a DC power transmission system transformer comprises the following steps:
determining the voltage of the primary winding of the direct current transmission system transformer to be regulated according to the voltage required to be output by the secondary winding of the direct current transmission system transformer and the transformation ratio of the direct current transmission system transformer;
determining a voltage modulation wave of a pressure regulating valve bridge arm according to the voltage of the primary winding, the transformation ratio of the pressure regulating transformer, the current flowing through the primary winding of the pressure regulating transformer or the current flowing through the secondary winding of the pressure regulating transformer and the direct-current voltage of the direct-current side of the pressure regulating valve; based on the voltage modulation wave corresponding to the pressure regulating valve bridge arm, controlling all sub-modules in the pressure regulating valve bridge arm, so that the pressure regulating valve and the pressure regulating transformer output the voltage to be regulated, and regulating the voltage of a direct current transmission system transformer; and
and determining a voltage modulation wave of the connecting valve bridge arm according to the voltage of a certain alternating current bus connected to the converter station in parallel after the secondary winding of the connecting transformer is connected with the connecting switch in series, the transformation ratio of the connecting transformer, the current flowing through the primary winding of the connecting transformer or the current flowing through the secondary winding of the connecting transformer and a direct current voltage command required by the direct current side of the connecting valve, and controlling all sub-modules in the connecting valve bridge arm based on the voltage modulation wave corresponding to the connecting valve bridge arm so that the direct current side of the connecting valve outputs the required direct current voltage.
Further, when the active power absorbed by the pressure regulating valve from the pressure regulating transformer is larger than the active power output by the pressure regulating valve to the pressure regulating transformer, the connecting valve is controlled to feed back redundant active power to an alternating current bus through a command of the direct current voltage of the direct current side of the connecting valve, so that the direct current voltage of the connecting valve or the direct current side of the pressure regulating valve is stabilized; when the active power absorbed by the pressure regulating valve from the pressure regulating transformer is smaller than the active power output by the pressure regulating valve to the pressure regulating transformer, the connecting valve is controlled to absorb the active power from an alternating current bus by a direct current voltage command of the direct current side of the connecting valve, and the direct current voltage of the connecting valve or the direct current side of the pressure regulating valve is stabilized.
Further, the output voltage of the pressure regulating valve and the voltage regulating transformer is regulated to be opposite to the voltage phase of the primary winding of the DC power transmission system transformer, and the voltage amplitude of the DC power transmission system transformer is increased; the output voltage of the pressure regulating valve and the voltage regulating transformer is regulated to be the same as the voltage phase of the primary winding of the DC power transmission system transformer, so that the voltage amplitude of the DC power transmission system transformer is reduced; the phase positions of the output voltages of the pressure regulating valve and the pressure regulating transformer are regulated, and the voltage zero crossing point of the direct current transmission system transformer is regulated; and simultaneously or separately regulating the output voltage of the pressure regulating valve and the output voltage of the regulating transformer to realize continuous regulation of the voltage of the transformer of the direct current transmission system.
Further, when the modularized multi-level voltage regulating device of the direct current transmission system transformer fails, the bypass switch on the voltage regulating side is closed or the connecting switch is disconnected, and the modularized multi-level voltage regulating device of the direct current transmission system transformer is cut off.
A control system for a modular multi-level voltage regulator for a dc power transmission system transformer, comprising:
the primary winding voltage calculation unit is used for determining the voltage of the primary winding of the direct current transmission system transformer to be regulated according to the voltage required to be output by the secondary winding of the direct current transmission system transformer and the transformation ratio of the direct current transmission system transformer;
the regulating valve bridge arm modulation wave calculation unit is used for determining the modulation ratio, the frequency and the phase of the voltage modulation wave of the regulating valve bridge arm according to the voltage of the primary winding of the direct current transmission system transformer, the transformation ratio of the regulating transformer, the current flowing through the primary winding of the regulating transformer or the current flowing through the secondary winding of the regulating transformer and the direct current voltage of the direct current side of the regulating valve, which are required to be regulated;
the regulating valve submodule control unit is used for controlling all submodules in the pressure regulating valve bridge arm based on the voltage modulation wave corresponding to the pressure regulating valve bridge arm, so that the pressure regulating valve and the pressure regulating transformer output the voltage to be regulated, and the voltage of the direct current transmission system transformer is regulated;
a connection valve bridge arm modulation wave calculation unit, which determines a voltage modulation wave of the connection valve bridge arm according to a voltage of an alternating current bus connected to a converter station in parallel after a secondary winding of the connection transformer is connected in series with the connection switch, a transformation ratio of the connection transformer, a current flowing through a primary winding of the connection transformer or a current flowing through the secondary winding of the connection transformer, and a direct current voltage instruction required by a direct current side of the connection valve;
and the connecting valve submodule control unit is used for controlling all submodules in the connecting valve bridge arm based on the voltage modulation wave corresponding to the connecting valve bridge arm, so that the direct-current side of the connecting valve outputs the required direct-current voltage.
Further, the control system further includes:
a connection valve direct current side control unit for controlling the connection valve to feed back surplus active power to an alternating current bus by generating a command of direct current voltage of the connection valve when active power absorbed by the pressure regulating valve from the pressure regulating transformer is larger than active power output by the pressure regulating valve to the pressure regulating transformer, and stabilizing the direct current voltage of the connection valve or the pressure regulating valve; when the active power absorbed by the pressure regulating valve from the pressure regulating transformer is smaller than the active power output by the pressure regulating valve to the pressure regulating transformer, the connecting valve is controlled to absorb the active power from an alternating current bus by generating a command of the direct current voltage of the direct current side of the connecting valve, and the direct current voltage of the connecting valve or the direct current side of the pressure regulating valve is stabilized.
Further, the control system further includes:
the output voltage adjusting unit is used for adjusting the output voltage of the pressure regulating valve and the voltage adjusting transformer to be opposite to the voltage phase of the primary winding of the DC power transmission system transformer and increasing the voltage amplitude of the DC power transmission system transformer; the output voltage of the pressure regulating valve and the voltage regulating transformer is regulated to be the same as the voltage phase of the primary winding of the DC power transmission system transformer, so that the voltage amplitude of the DC power transmission system transformer is reduced; the phase positions of the output voltages of the pressure regulating valve and the pressure regulating transformer are regulated, and the voltage zero crossing point of the direct current transmission system transformer is regulated; and simultaneously or separately regulating the output voltage of the pressure regulating valve and the output voltage of the regulating transformer to realize continuous regulation of the voltage of the transformer of the direct current transmission system.
Further, the control system further includes:
and the switch control unit is used for controlling the on-off of the bypass switch at the voltage regulating side or the off-off of the connecting switch when the modularized multi-level voltage regulating device of the direct current transmission system transformer fails, and cutting off the modularized multi-level voltage regulating device of the direct current transmission system transformer.
The beneficial effects brought by adopting the technical scheme are that:
1. the modularized multi-level voltage regulating device of the direct current transmission system transformer can replace a traditional mechanical transformer on-load tap-changer, avoid frequent faults of the existing direct current transmission project tap-changer, solve the problems of high fault rate, high maintenance cost and the like of the traditional mechanical transformer on-load tap-changer, and further reduce the pressure of long-term reliable operation in ultra-high voltage projects;
2. compared with the traditional mechanical transformer on-load tap changer which can only regulate the primary side voltage of the transformer of the direct current transmission system in a grading way, the voltage regulating device, the control method and the control system thereof based on the power electronic device can continuously change the voltage of the pressure regulating valve, thereby continuously regulating the primary side voltage of the transformer of the direct current transmission system;
3. according to the modularized multi-level voltage regulating device of the direct current transmission system transformer, the number of cascade sub-modules of bridge arms in the pressure regulating valve or the connecting valve can be changed by changing the transformation ratio of the voltage regulating transformer or the connecting transformer, so that the cost and the occupied area are reduced;
4. according to the modularized multi-level voltage regulating device of the direct current transmission system transformer, when the submodules are in fault, the submodules can be bypassed through the bypass switch, so that the normal operation of the system is not affected, and when a plurality of submodules are arranged in the connecting valve or the pressure regulating valve, the submodules can be mutually redundant, so that the normal operation of the system is ensured, the maintenance is simple and easy, and the availability is high;
5. according to the voltage regulating device, the control method and the control system thereof, when the modularized multi-level voltage regulating device of the direct current transmission system transformer has system faults, the modularized multi-level voltage regulating device of the direct current transmission system transformer can be cut off by means of closing the voltage regulating side bypass switch, disconnecting the connecting switch and the like, so that the influence on the direct current transmission system is avoided.
Drawings
FIG. 1 is a schematic diagram of a conventional mechanical transformer on-load tap changer;
fig. 2 is a schematic diagram of a modular multi-level voltage regulator of a dc power transmission system transformer according to the present invention;
FIG. 3 is a schematic diagram of a sub-module according to the present invention;
FIG. 4 is a schematic diagram of another sub-module according to the present invention;
fig. 5 is a schematic diagram of a control system according to the present invention.
Description of the reference numerals: 1. on-load tap-changer of traditional mechanical transformer; 2. a change-over switch; 3. a tap; 4. a voltage regulating winding; 5. modularized multi-level voltage regulating device of DC power transmission system transformer; 6. a connecting valve; 7. bridge arm valves; 8. a sub-module; 9. a connection switch; 10. connecting a transformer; 11. a voltage regulating side bypass switch; 12. a step-down transformer; 13. a pressure regulating valve; 14. a DC power transmission system transformer; 15. a direct current transmission system converter valve; 16. primary side alternating current bus of direct current transmission system transformer; 17. a certain ac busbar of the converter station; 18. a direct current positive bus of a converter valve of the direct current transmission system; 19. a direct current negative bus of a converter valve of the direct current transmission system; 20. a switching device; 21. a capacitor; 22. a bypass switch; 23. and (3) resistance.
Detailed Description
The technical scheme of the present invention will be described in detail below with reference to the accompanying drawings.
The invention provides a modularized multi-level voltage regulating device of a direct current transmission system transformer, which comprises a connecting switch, a voltage regulating side bypass switch, a connecting transformer, a voltage regulating transformer, a connecting valve and a pressure regulating valve, wherein the pressure regulating valve or the connecting valve is composed of bridge arms and is an H bridge, the direct current side of the pressure regulating valve is connected in parallel with the direct current side of the connecting valve, two midpoints of the H bridge of the pressure regulating valve are connected to a primary winding of the voltage regulating transformer, a secondary winding of the voltage regulating transformer is connected between a low-voltage side of the primary winding of the direct current transmission system transformer and the ground in series, the two midpoints of the H bridge of the connecting valve are connected to the primary winding of the connecting transformer, and the secondary winding of the connecting transformer is connected with a certain alternating current bus of a converter station in parallel after being connected with the connecting switch in series.
In this embodiment, preferably, the bridge arm is formed by connecting a bridge arm valve and a reactor in series, and the bridge arm valve is formed by cascading 1 or more sub-modules. Further, there are two implementation manners of the submodule, one of which is shown in fig. 3, where the submodule at least includes two switching devices, a capacitor, a resistor and a bypass switch, the two switching devices are connected in series and then connected in parallel with the capacitor, the bypass switch is connected in parallel with one of the switching devices, and the resistor is connected in parallel with the capacitor; the other is shown in fig. 4, and the submodule at least comprises four switching devices, a capacitor, a resistor and a bypass switch, wherein the four switching devices form a full-bridge circuit, the full-bridge circuit is connected with the capacitor in parallel, the bypass switch is connected with two midpoints of the full-bridge circuit in parallel, and the resistor is connected with the capacitor in parallel.
In this embodiment, preferably, the voltage regulating side bypass switch is a fast mechanical switch or a power electronic switch, and is connected in parallel to two ends of the secondary winding of the voltage regulating transformer.
Based on the device, the invention also provides a control method of the modularized multi-level voltage regulating device of the direct current transmission system transformer, which comprises the following steps:
determining the voltage of the primary winding of the direct current transmission system transformer to be regulated according to the voltage required to be output by the secondary winding of the direct current transmission system transformer and the transformation ratio of the direct current transmission system transformer;
according to the voltage of the primary winding of the direct current transmission system transformer to be regulated, the transformation ratio of the regulating transformer, the current flowing through the primary winding of the regulating transformer or the current flowing through the secondary winding of the regulating transformer and the direct current voltage on the direct current side of the pressure regulating valve, the modulation ratio, the frequency and the phase of the voltage modulation wave of the pressure regulating valve bridge arm are determined (the specific voltage modulation wave can be determined according to the modulation ratio, the frequency and the phase), and the control of all the submodules in the pressure regulating valve bridge arm is carried out based on the voltage modulation wave corresponding to the pressure regulating valve bridge arm, so that the pressure regulating valve and the regulating transformer output the voltage to be regulated, and the voltage of the direct current transmission system transformer is regulated;
according to the voltage of an alternating current bus connected to a converter station in parallel after the secondary winding of the connecting transformer is connected with the connecting switch in series, the transformation ratio of the connecting transformer, the current flowing through the primary winding of the connecting transformer or the current flowing through the secondary winding of the connecting transformer, and the direct current voltage command required by the direct current side of the connecting valve, the modulation ratio, frequency and phase of the voltage modulation wave of the connecting valve bridge arm are determined, and the control of all the submodules in the connecting valve bridge arm is performed based on the voltage modulation wave corresponding to the connecting valve bridge arm, so that the connecting valve direct current side outputs the required direct current voltage.
In this embodiment, preferably, when the active power absorbed by the pressure regulating valve from the voltage regulating transformer is greater than the active power output by the pressure regulating valve to the voltage regulating transformer, the direct-current voltage of the connecting valve or the pressure regulating valve tends to rise, and the connecting valve is controlled to feed back the redundant active power into the alternating-current bus by the command of the direct-current voltage of the direct-current side of the connecting valve, so that the direct-current voltage of the direct-current side of the connecting valve or the pressure regulating valve is stabilized; when the active power absorbed by the pressure regulating valve from the pressure regulating transformer is smaller than the active power output by the pressure regulating valve to the pressure regulating transformer, the direct current voltage of the connecting valve or the pressure regulating valve tends to be reduced, and the connecting valve is controlled to absorb the active power from the alternating current bus by a command of the direct current voltage of the direct current side of the connecting valve, so that the direct current voltage of the connecting valve or the pressure regulating valve is stabilized.
In this embodiment, preferably, the output voltage of the regulating valve and the regulating transformer is opposite to the voltage of the primary winding of the dc power transmission system transformer, so as to raise the voltage amplitude of the dc power transmission system transformer; the output voltage of the pressure regulating valve and the pressure regulating transformer is the same as the voltage phase of the primary winding of the DC power transmission system transformer, so that the voltage amplitude of the DC power transmission system transformer is reduced; the phase of the output voltage of the pressure regulating valve and the voltage regulating transformer is regulated, and the voltage zero crossing point of the direct current transmission system transformer is regulated; and simultaneously or separately regulating the output voltage of the pressure regulating valve and the output voltage of the regulating transformer to realize continuous regulation of the voltage of the transformer of the direct current transmission system.
In this embodiment, preferably, when a system fault occurs in the modular multi-level voltage regulator of the dc power transmission system transformer, the voltage regulating side bypass switch is turned on or the connection switch is turned off, and the modular multi-level voltage regulator of the dc power transmission system transformer is disconnected.
The invention also provides a control system of the modularized multi-level voltage regulating device of the direct current transmission system transformer, as shown in fig. 5, comprising:
the primary winding voltage calculation unit is used for determining the voltage of the primary winding of the direct current transmission system transformer to be regulated according to the voltage required to be output by the secondary winding of the direct current transmission system transformer and the transformation ratio of the direct current transmission system transformer;
the regulating valve bridge arm modulation wave calculation unit is used for determining the modulation ratio, the frequency and the phase of the voltage modulation wave of the regulating valve bridge arm according to the voltage of the primary winding of the direct current transmission system transformer, the transformation ratio of the regulating transformer, the current flowing through the primary winding of the regulating transformer or the current flowing through the secondary winding of the regulating transformer and the direct current voltage of the direct current side of the regulating valve, which are required to be regulated;
the regulating valve submodule control unit is used for controlling all submodules in the pressure regulating valve bridge arm based on the voltage modulation wave corresponding to the pressure regulating valve bridge arm, so that the pressure regulating valve and the pressure regulating transformer output the voltage to be regulated, and the voltage of the direct current transmission system transformer is regulated;
a connection valve bridge arm modulation wave calculation unit, which determines the modulation ratio, frequency and phase of the voltage modulation wave of the connection valve bridge arm according to the voltage of a certain alternating current bus connected to the converter station in parallel after the secondary winding of the connection transformer is connected in series with the connection switch, the transformation ratio of the connection transformer, the current flowing through the primary winding of the connection transformer or the current flowing through the secondary winding of the connection transformer and the direct current voltage command required by the direct current side of the connection valve;
the connecting valve submodule control unit is used for controlling all submodules in the connecting valve bridge arm based on the voltage modulation wave corresponding to the connecting valve bridge arm so that the direct-current side of the connecting valve outputs the required direct-current voltage;
a connection valve direct current side control unit for controlling the connection valve to feed back surplus active power to an alternating current bus by generating a command of direct current voltage of the connection valve when active power absorbed by the pressure regulating valve from the pressure regulating transformer is larger than active power output by the pressure regulating valve to the pressure regulating transformer, and stabilizing the direct current voltage of the connection valve or the pressure regulating valve; when the active power absorbed by the pressure regulating valve from the pressure regulating transformer is smaller than the active power output by the pressure regulating valve to the pressure regulating transformer, the connecting valve is controlled to absorb the active power from an alternating current bus by generating a command of the direct current voltage of the direct current side of the connecting valve, so that the direct current voltage of the connecting valve or the direct current side of the pressure regulating valve is stabilized;
the output voltage adjusting unit is used for adjusting the output voltage of the pressure regulating valve and the voltage adjusting transformer to be opposite to the voltage phase of the primary winding of the DC power transmission system transformer and increasing the voltage amplitude of the DC power transmission system transformer; the output voltage of the pressure regulating valve and the voltage regulating transformer is regulated to be the same as the voltage phase of the primary winding of the DC power transmission system transformer, so that the voltage amplitude of the DC power transmission system transformer is reduced; the phase positions of the output voltages of the pressure regulating valve and the pressure regulating transformer are regulated, and the voltage zero crossing point of the direct current transmission system transformer is regulated; simultaneously or separately regulating the output voltage of the pressure regulating valve and the voltage regulating transformer to realize continuous regulation of the voltage of the transformer of the direct current transmission system;
and the switch control unit is used for controlling the on-off of the bypass switch at the voltage regulating side or the off-off of the connecting switch when the modularized multi-level voltage regulating device of the direct current transmission system transformer fails, and cutting off the modularized multi-level voltage regulating device of the direct current transmission system transformer.
It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may 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 instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may 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 flow or flows and/or block diagram block or blocks.
It should be finally understood that the foregoing embodiments are merely illustrative of the technical solutions of the present invention and not limiting the scope of protection thereof, and although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that various changes, modifications or equivalents may be made to the specific embodiments of the invention, and these changes, modifications or equivalents are within the scope of protection of the claims appended hereto.
Claims (14)
1. The utility model provides a many level of modularization voltage regulation device of direct current transmission system transformer which characterized in that: the device comprises a connecting switch, a connecting transformer, a voltage regulating transformer, a connecting valve and a pressure regulating valve; the pressure regulating valve and the connecting valve are H-bridge structures formed by bridge arms;
the direct current side of the pressure regulating valve is connected with the direct current side of the connecting valve in parallel, and two midpoints of an H bridge of the pressure regulating valve are connected to a primary winding of the pressure regulating transformer;
the secondary winding of the voltage regulating transformer is connected in series between the low-voltage side of the primary winding of the DC transmission system transformer and the ground;
two midpoints of the H bridge of the connecting valve are connected to a primary winding of the connecting transformer, and a secondary winding of the connecting transformer is connected in series with the connecting switch and then connected in parallel to a certain alternating current bus of the converter station.
2. The modular multilevel voltage regulator of a dc power transmission system transformer of claim 1, wherein: the bridge arm is formed by connecting a bridge arm valve and a reactor in series, and the bridge arm valve comprises a submodule or is formed by cascading a plurality of submodules.
3. The modular multilevel voltage regulator of a dc power transmission system transformer of claim 2, wherein: the submodule at least comprises two switching devices, a capacitor, a resistor and a bypass switch, wherein the two switching devices are connected in series and then connected with the capacitor and the resistor in parallel, and the bypass switch is connected with one switching device in parallel.
4. The modular multilevel voltage regulator of a dc power transmission system transformer of claim 2, wherein: the submodule at least comprises four switching devices, a capacitor, a resistor and a bypass switch, wherein the four switching devices form a full-bridge circuit, the full-bridge circuit is connected with the capacitor and the resistor in parallel, and the bypass switch is connected with two midpoints of the full-bridge circuit in parallel.
5. The modular multilevel voltage regulator of a dc power transmission system transformer of any one of claims 1-4, wherein: the transformer also comprises a voltage regulating side bypass switch which is connected in parallel with two ends of the secondary winding of the voltage regulating transformer.
6. The modular multilevel voltage regulator of a dc power transmission system transformer of claim 5, wherein: the voltage regulating side bypass switch is a quick mechanical switch or a power electronic switch.
7. The control method of the modularized multi-level voltage regulating device of the direct current transmission system transformer is characterized by comprising the following steps:
determining the voltage of the primary winding of the direct current transmission system transformer to be regulated according to the voltage required to be output by the secondary winding of the direct current transmission system transformer and the transformation ratio of the direct current transmission system transformer;
determining a voltage modulation wave of a pressure regulating valve bridge arm according to the voltage of the primary winding, the transformation ratio of the pressure regulating transformer, the current flowing through the primary winding of the pressure regulating transformer or the current flowing through the secondary winding of the pressure regulating transformer and the direct-current voltage of the direct-current side of the pressure regulating valve; based on the voltage modulation wave corresponding to the pressure regulating valve bridge arm, controlling all sub-modules in the pressure regulating valve bridge arm, so that the pressure regulating valve and the pressure regulating transformer output the voltage to be regulated, and regulating the voltage of a direct current transmission system transformer; and
and determining a voltage modulation wave of the connecting valve bridge arm according to the voltage of a certain alternating current bus connected to the converter station in parallel after the secondary winding of the connecting transformer is connected with the connecting switch in series, the transformation ratio of the connecting transformer, the current flowing through the primary winding of the connecting transformer or the current flowing through the secondary winding of the connecting transformer and a direct current voltage command required by the direct current side of the connecting valve, and controlling all sub-modules in the connecting valve bridge arm based on the voltage modulation wave corresponding to the connecting valve bridge arm so that the direct current side of the connecting valve outputs the required direct current voltage.
8. The control method of the modular multilevel voltage regulator of a dc power transmission system transformer of claim 7, wherein: when the active power absorbed by the pressure regulating valve from the pressure regulating transformer is larger than the active power output by the pressure regulating valve to the pressure regulating transformer, the connecting valve is controlled to feed back redundant active power to an alternating current bus through a direct current voltage command of the direct current side of the connecting valve, so that the direct current voltage of the connecting valve or the pressure regulating valve is stabilized; when the active power absorbed by the pressure regulating valve from the pressure regulating transformer is smaller than the active power output by the pressure regulating valve to the pressure regulating transformer, the connecting valve is controlled to absorb the active power from an alternating current bus by a direct current voltage command of the direct current side of the connecting valve, and the direct current voltage of the connecting valve or the direct current side of the pressure regulating valve is stabilized.
9. The control method of the modular multilevel voltage regulator of a dc power transmission system transformer of claim 7, wherein: regulating the output voltage of the pressure regulating valve and the voltage regulating transformer to be opposite to the voltage phase of the primary winding of the DC transmission system transformer, and increasing the voltage amplitude of the DC transmission system transformer; the output voltage of the pressure regulating valve and the voltage regulating transformer is regulated to be the same as the voltage phase of the primary winding of the DC power transmission system transformer, so that the voltage amplitude of the DC power transmission system transformer is reduced; the phase positions of the output voltages of the pressure regulating valve and the pressure regulating transformer are regulated, and the voltage zero crossing point of the direct current transmission system transformer is regulated; and simultaneously or separately regulating the output voltage of the pressure regulating valve and the output voltage of the regulating transformer to realize continuous regulation of the voltage of the transformer of the direct current transmission system.
10. The control method of the modular multilevel voltage regulator of a dc power transmission system transformer of claim 7, wherein: when the modularized multi-level voltage regulating device of the direct current transmission system transformer fails, the bypass switch on the voltage regulating side is closed or the connecting switch is disconnected, and the modularized multi-level voltage regulating device of the direct current transmission system transformer is cut off.
11. A control system for a modular multi-level voltage regulator for a dc power transmission system transformer, comprising:
the primary winding voltage calculation unit is used for determining the voltage of the primary winding of the direct current transmission system transformer to be regulated according to the voltage required to be output by the secondary winding of the direct current transmission system transformer and the transformation ratio of the direct current transmission system transformer;
the regulating valve bridge arm modulation wave calculation unit is used for determining the modulation ratio, the frequency and the phase of the voltage modulation wave of the regulating valve bridge arm according to the voltage of the primary winding of the direct current transmission system transformer, the transformation ratio of the regulating transformer, the current flowing through the primary winding of the regulating transformer or the current flowing through the secondary winding of the regulating transformer and the direct current voltage of the direct current side of the regulating valve, which are required to be regulated;
the regulating valve submodule control unit is used for controlling all submodules in the pressure regulating valve bridge arm based on the voltage modulation wave corresponding to the pressure regulating valve bridge arm, so that the pressure regulating valve and the pressure regulating transformer output the voltage to be regulated, and the voltage of the direct current transmission system transformer is regulated;
a connection valve bridge arm modulation wave calculation unit, which determines a voltage modulation wave of the connection valve bridge arm according to a voltage of an alternating current bus connected to a converter station in parallel after a secondary winding of the connection transformer is connected in series with the connection switch, a transformation ratio of the connection transformer, a current flowing through a primary winding of the connection transformer or a current flowing through the secondary winding of the connection transformer, and a direct current voltage instruction required by a direct current side of the connection valve;
and the connecting valve submodule control unit is used for controlling all submodules in the connecting valve bridge arm based on the voltage modulation wave corresponding to the connecting valve bridge arm, so that the direct-current side of the connecting valve outputs the required direct-current voltage.
12. The control system of a modular multi-level voltage regulator of a dc power transmission system transformer of claim 11, further comprising:
a connection valve direct current side control unit for controlling the connection valve to feed back surplus active power to an alternating current bus by generating a command of direct current voltage of the connection valve when active power absorbed by the pressure regulating valve from the pressure regulating transformer is larger than active power output by the pressure regulating valve to the pressure regulating transformer, and stabilizing the direct current voltage of the connection valve or the pressure regulating valve; when the active power absorbed by the pressure regulating valve from the pressure regulating transformer is smaller than the active power output by the pressure regulating valve to the pressure regulating transformer, the connecting valve is controlled to absorb the active power from an alternating current bus by generating a command of the direct current voltage of the direct current side of the connecting valve, and the direct current voltage of the connecting valve or the direct current side of the pressure regulating valve is stabilized.
13. The control system of a modular multi-level voltage regulator of a dc power transmission system transformer of claim 11, further comprising:
the output voltage adjusting unit is used for adjusting the output voltage of the pressure regulating valve and the voltage adjusting transformer to be opposite to the voltage phase of the primary winding of the DC power transmission system transformer and increasing the voltage amplitude of the DC power transmission system transformer; the output voltage of the pressure regulating valve and the voltage regulating transformer is regulated to be the same as the voltage phase of the primary winding of the DC power transmission system transformer, so that the voltage amplitude of the DC power transmission system transformer is reduced; the phase positions of the output voltages of the pressure regulating valve and the pressure regulating transformer are regulated, and the voltage zero crossing point of the direct current transmission system transformer is regulated; and simultaneously or separately regulating the output voltage of the pressure regulating valve and the output voltage of the regulating transformer to realize continuous regulation of the voltage of the transformer of the direct current transmission system.
14. The control system of a modular multi-level voltage regulator of a dc power transmission system transformer of claim 11, further comprising:
and the switch control unit is used for controlling the on-off of the bypass switch at the voltage regulating side or the off-off of the connecting switch when the modularized multi-level voltage regulating device of the direct current transmission system transformer fails, and cutting off the modularized multi-level voltage regulating device of the direct current transmission system transformer.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117060406A (en) * | 2023-10-12 | 2023-11-14 | 四川大学 | Operation method of flexible direct current transmission system based on OWT-DMMC |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117060406A (en) * | 2023-10-12 | 2023-11-14 | 四川大学 | Operation method of flexible direct current transmission system based on OWT-DMMC |
| CN117060406B (en) * | 2023-10-12 | 2023-12-08 | 四川大学 | Operation method of flexible direct current transmission system based on OWT-DMMC |
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