CN114520585A - Harmonic reactance regulating system of modular multilevel converter - Google Patents
Harmonic reactance regulating system of modular multilevel converter Download PDFInfo
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- CN114520585A CN114520585A CN202210153405.3A CN202210153405A CN114520585A CN 114520585 A CN114520585 A CN 114520585A CN 202210153405 A CN202210153405 A CN 202210153405A CN 114520585 A CN114520585 A CN 114520585A
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- modular multilevel
- multilevel converter
- harmonic
- reactance
- bridge arm
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/12—Arrangements for reducing harmonics from ac input or output
- H02M1/126—Arrangements for reducing harmonics from ac input or output using passive filters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/483—Converters with outputs that each can have more than two voltages levels
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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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- Engineering & Computer Science (AREA)
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Abstract
The invention discloses a harmonic reactance regulating system of a modular multilevel converter, which comprises: the device comprises a converter transformer, a harmonic reactance regulating device, modular multilevel converter upper and lower bridge arm cascade modules and bridge arm reactors connected in series between upper and lower bridge arms of the modular multilevel converter upper and lower bridge arm cascade modules; the harmonic reactance adjusting device is connected between the converter transformer and the bridge arm reactor in series and used for adjusting harmonic reactance at an outlet of the modular multilevel converter. According to the harmonic reactance adjusting system of the modular multilevel converter, provided by the invention, the harmonic reactance adjusting device is used for increasing the margin for the harmonic impedance design of the modular multilevel converter, so that the equipment debugging time is not influenced, the cost is greatly saved, the risk of engineering brought by one-sided selected parameters is reduced, and accurate parameter guidance can be provided for the design of products of the same type.
Description
Technical Field
The invention relates to the technical field of flexible direct current power transmission and transformation equipment, in particular to a harmonic reactance adjusting system of a modular multilevel converter.
Background
With the rapid development of the flexible direct-current transmission technology, the advantages of the modular multi-level converter are more and more obvious compared with a two-level converter and a three-level converter. Because the modular multilevel converter usually has a large number of levels, the output voltage step wave is very close to a sine wave, and the harmonic content is less. It is also not generally necessary to install a special ac filter in order to reduce the burden on the control system. Under the condition of not considering other factors such as the number of levels, control technology and the like, in order to obtain a current output waveform of the converter with better quality, harmonic waves at the outlet of the converter are usually suppressed by harmonic impedance, and the harmonic impedance at the position is the sum of 0.5 time of the series reactance of the bridge arm and the leakage reactance of the converter transformer.
In order to make the output waveform meet the use requirement, when the harmonic impedance is designed to be small, the existing solution usually replaces a larger converter transformer or a bridge arm reactor for the converter. However, the cabinet body of the equipment in the middle and low voltage field is compact, and the whole insulation of the equipment can be influenced by forced replacement. Therefore, the method of modifying the equipment not only occupies a large amount of time and is not easy to implement, but also brings about greater resource waste.
Disclosure of Invention
The invention aims to provide a harmonic reactance regulating system of a modular multilevel converter, which aims to solve the problems of long time consumption, difficult implementation and easy equipment damage of an equipment modifying mode adopted under the condition of small harmonic impedance design in the prior art.
In order to achieve the above object, the present invention provides a harmonic reactance adjusting system for a modular multilevel converter, including:
the device comprises a converter transformer, a harmonic reactance regulating device, modular multilevel converter upper and lower bridge arm cascade modules and bridge arm reactors connected in series between upper and lower bridge arms of the modular multilevel converter upper and lower bridge arm cascade modules; wherein, the first and the second end of the pipe are connected with each other,
the harmonic reactance adjusting device is connected between the converter transformer and the bridge arm reactor in series and used for adjusting harmonic reactance at an outlet of the modular multilevel converter.
Further, preferably, the harmonic reactance adjusting device includes a plurality of sets of adjusting units composed of single-phase reactors.
Further, it is preferable that the number of the adjusting units is 3.
Further, it is preferable that the number of the single-phase reactors in each set of the regulating units is the same.
Further, preferably, the value of the single-phase reactor is smaller than the leakage reactance of the converter transformer.
Further, preferably, a value of the single-phase reactor is smaller than a bridge arm reactance of the bridge arm reactor.
Further, preferably, the value range of the single-phase reactor includes 0.2-2 mH.
Further, preferably, the harmonic reactance adjusting device is further configured to adjust the harmonic reactance at the outlet of the modular multilevel converter by changing the series-parallel connection mode of the single-phase reactor.
Further, preferably, the harmonic reactance adjusting device is further configured to not switch in a three-phase loop when a debugging phase of the modular multilevel converter does not meet a preset condition.
Further, preferably, the harmonic reactance adjusting device is a detachable and recyclable device.
Compared with the prior art, the invention has the beneficial effects that:
the invention discloses a harmonic reactance regulating system of a modular multilevel converter, which comprises: the device comprises a converter transformer, a harmonic reactance regulating device, modular multilevel converter upper and lower bridge arm cascade modules and bridge arm reactors connected in series between upper and lower bridge arms of the modular multilevel converter upper and lower bridge arm cascade modules; the harmonic reactance adjusting device is connected between the converter transformer and the bridge arm reactor in series and used for adjusting harmonic reactance at an outlet of the modular multilevel converter. According to the harmonic reactance adjusting system of the modular multilevel converter, provided by the invention, the harmonic reactance adjusting device is used for increasing the margin for the harmonic impedance design of the modular multilevel converter, so that the equipment debugging time is not influenced, the cost is greatly saved, the risk of engineering brought by one-sided selected parameters is reduced, and accurate parameter guidance can be provided for the design of products of the same type.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a harmonic reactance adjustment system of a modular multilevel converter according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a harmonic reactance adjustment system for a modular multilevel converter according to another embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be understood that the step numbers used herein are for convenience of description only and are not intended as limitations on the order in which the steps are performed.
It is to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
The terms "comprises" and "comprising" indicate the presence of the described features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
The term "and/or" refers to any and all possible combinations of one or more of the associated listed items and includes such combinations.
Referring to fig. 1, an embodiment of the invention provides a harmonic reactance adjustment system for a modular multilevel converter. As shown in fig. 1, the harmonic reactance regulating system of the modular multilevel converter comprises the following four parts:
the device comprises a converter transformer 01, a harmonic reactance regulating device 02, modular multilevel converter upper and lower bridge arm cascade modules and bridge arm reactors 05 connected in series between upper and lower bridge arms of the modular multilevel converter upper and lower bridge arm cascade modules;
The modular multilevel converter upper and lower bridge arm cascade module comprises a modular multilevel converter upper bridge arm 03 and a modular multilevel converter lower bridge arm 04;
the harmonic reactance adjusting device 02 is connected in series between the converter transformer 01 and the bridge arm reactor 05 and is used for adjusting the harmonic reactance at the outlet of the modular multilevel converter.
In this embodiment, it should be noted that six bridge arms of a modular multilevel converter (MMC for short) are not formed by connecting a plurality of switching devices in series, but adopt a sub-module cascade mode. Because the high-capacity direct current converter is constructed by adopting a plurality of sub-modules, the high-capacity direct current converter has the advantages of reduced manufacturing difficulty, good waveform quality, reduced step voltage, doubled loss, strong fault handling capability and the like, and is widely applied to a flexible direct current transmission system. In practical application, under the condition of not considering other factors such as level number, control technology and the like, in order to obtain a better-quality converter current output waveform, harmonic waves at the outlet of a converter are usually suppressed by harmonic wave impedance, but the operation is different from the actual operation condition of the modular multilevel converter equipment. In the prior art, in order to enable an output waveform to meet use requirements, when an error exists between harmonic impedance design and actual harmonic impedance, a bridge arm reactor 05 or a converter transformer 01 is usually directly replaced, and the mode of rectifying and modifying equipment is not only complex in operation, but also often influences normal use of the equipment. Therefore, the present embodiment aims at providing a harmonic reactance adjustment system for a modular multilevel converter, which can effectively adjust the unknown harmonic impedance output by the modular multilevel converter, and avoid the problem of resource waste caused by the influence of the existing method on the equipment.
Specifically, in the present embodiment, a standby harmonic reactance adjustment device 02 is mainly connected in series between the bridge arm reactor 05 and the converter transformer 01 of the modular multilevel converter, that is, an adjustment margin is added to an originally fixed harmonic reactance design value.
In a specific embodiment, the converter transformer 01, the harmonic reactance adjusting device 02, the modular multilevel converter upper and lower bridge arm cascade modules, and the bridge arm reactors 05 need to be placed in respective cabinets and then connected, as shown in fig. 2. The harmonic reactance adjusting device 02 comprises a plurality of groups of adjusting units, each group of adjusting units is composed of a plurality of single-phase reactors, and A, B, C three layers of adjusting units are respectively corresponding to the adjusting units in fig. 2.
In a preferred embodiment, the number of the regulating units is 3, and the number of the single-phase reactors in each group of the regulating units is the same. In addition, the single-phase reactor is mainly a single-phase reactor with a value smaller than the leakage reactance of the converter transformer 01 and the numerical value of the bridge arm reactance of the bridge arm reactor 05. Specifically, the value range of the single-phase reactor comprises 0.2-2 mH.
In a specific embodiment, the harmonic reactance adjusting device 02 is mainly used for flexibly changing the series-parallel connection mode of the reactor according to the requirement of system parameters of the equipment, so as to optimize the performance of the MMC. Specifically, the connecting reactance value of the outlet of the converter transformer 01 is changed in an increasing or reducing mode, the harmonic impedance of the outlet of the MMC can be flexibly changed during debugging, timely compensation can be carried out when the harmonic reactance is designed to be small, the debugging progress of equipment is prevented from being influenced, and the stability of the converter in the debugging process in the flexible core operation process is improved.
In a specific embodiment, when the harmonic reactance adjusting device 02 is applied to debugging, the main process is as follows: and when the debugging stage of the modular multilevel converter does not meet the preset condition, the three-phase loop is not accessed. The preset conditions mainly refer to the debugging initial stage of equipment, namely when the MMC is in the debugging initial stage, the A/B/C three-layer single-phase reactors in the harmonic reactance regulating device 02 are not connected into an A/B/C three-phase loop, along with the debugging of a system, if the control strategy, the module voltage-sharing strategy and the device response are reliable, the harmonic content at the outlet of the converter is still very high, the single-phase reactors in the A/B/C three-layer reactors in the standby harmonic reactance regulating device 02 can be respectively connected into the A/B/C three-phase loop according to the required quantity, and the process can be gradually debugged according to the principle that the connection quantity is from small to large; if the system is debugged satisfactorily, the spare harmonic reactance adjusting device 02 is not used or the unused reactors in the device are not connected, the unused reactors can be taken out and recycled.
In summary, in the harmonic reactance adjustment system for the modular multilevel converter provided in the embodiment of the present invention, a harmonic reactance adjustment device is used to increase a margin for the harmonic impedance design of the modular multilevel converter, so that the device debugging time is not affected, the cost is greatly saved, the risk brought to the engineering by one-sided parameter selection is reduced, and accurate parameter guidance can be provided for the design of products of the same type.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical functional division, and there may be other divisions in actual practice, for example, multiple units or page components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection of devices or units through some interfaces, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, or in a form of hardware plus a software functional unit.
The integrated unit implemented in the form of a software functional unit may be stored in a computer-readable storage medium. The software functional unit is stored in a storage medium and includes several instructions to enable a computer device (which may be a personal computer, a server, or a network device) or a processor (processor) to execute some steps of the methods according to the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.
Claims (10)
1. A harmonic reactance adjustment system for a Modular Multilevel Converter (MMC), comprising:
the bridge arm reactor comprises a converter transformer, a harmonic reactance regulating device, a modular multilevel converter upper and lower bridge arm cascade module and a bridge arm reactor connected between an upper bridge arm and a lower bridge arm of the modular multilevel converter upper and lower bridge arm cascade module in series; wherein, the first and the second end of the pipe are connected with each other,
and the harmonic reactance regulating device is connected between the converter transformer and the bridge arm reactor in series and is used for regulating the harmonic reactance at the outlet of the modular multilevel converter.
2. The harmonic reactance adjustment system of the modular multilevel converter according to claim 1, wherein the harmonic reactance adjustment device comprises a plurality of groups of adjustment units composed of single-phase reactors.
3. The harmonic reactance regulation system of claim 2 wherein the number of said regulation units is 3 groups.
4. The harmonic reactance regulation system of a modular multilevel converter according to claim 2, wherein the number of single-phase reactors in each group of said regulation units is the same.
5. The harmonic reactance adjustment system of a modular multilevel converter according to claim 2, wherein the value of the single-phase reactor is smaller than the leakage reactance of the converter transformer.
6. The harmonic reactance adjustment system for the modular multilevel converter according to claim 2, wherein the value of the single-phase reactor is smaller than the bridge arm reactance of the bridge arm reactor.
7. The harmonic reactance regulation system of a modular multilevel converter according to any of claims 1 to 6, wherein the value range of the single-phase reactor comprises 0.2-2 mH.
8. The harmonic reactance adjustment system for the modular multilevel converter according to claim 7, wherein the harmonic reactance adjustment device is further configured to adjust the harmonic reactance of the outlet of the modular multilevel converter by changing the series-parallel connection of the single-phase reactors.
9. The harmonic reactance adjustment system for the modular multilevel converter according to claim 7, wherein the harmonic reactance adjustment device is further configured to not switch in a three-phase loop when a debugging stage of the modular multilevel converter does not satisfy a preset condition.
10. The harmonic reactance regulation system of a modular multilevel converter according to claim 7, wherein the harmonic reactance regulation device is a detachable and recyclable device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210153405.3A CN114520585A (en) | 2022-02-18 | 2022-02-18 | Harmonic reactance regulating system of modular multilevel converter |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210153405.3A CN114520585A (en) | 2022-02-18 | 2022-02-18 | Harmonic reactance regulating system of modular multilevel converter |
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| CN114520585A true CN114520585A (en) | 2022-05-20 |
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| CN202210153405.3A Pending CN114520585A (en) | 2022-02-18 | 2022-02-18 | Harmonic reactance regulating system of modular multilevel converter |
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- 2022-02-18 CN CN202210153405.3A patent/CN114520585A/en active Pending
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