CN113346782A - Bridge arm parallel type MMC parallel sub-bridge arm current sharing control method and device - Google Patents
Bridge arm parallel type MMC parallel sub-bridge arm current sharing control method and device Download PDFInfo
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- CN113346782A CN113346782A CN202110762613.9A CN202110762613A CN113346782A CN 113346782 A CN113346782 A CN 113346782A CN 202110762613 A CN202110762613 A CN 202110762613A CN 113346782 A CN113346782 A CN 113346782A
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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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- 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
- 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
- H02M1/32—Means for protecting converters other than automatic disconnection
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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
- H02M7/53—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 using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—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 using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—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 using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
- H02M7/53871—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 using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
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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 bridge arm parallel MMC parallel sub-bridge arm current-sharing control method and a device, wherein the method comprises the following steps: acquiring a circulating current value between parallel sub-bridge arms of the sub-bridge arm I and the sub-bridge arm II; calculating the superposition amount of the modulation waves of the bridge arms through damping coefficients according to the current values of the loop currents between the parallel sub-bridge arms; distributing the superposition amount of the modulation waves of the bridge arms according to a preset distribution proportion, and obtaining the superposition amount of the modulation waves of the first sub-bridge arm and the superposition amount of the modulation waves of the second sub-bridge arm after amplitude limiting; and combining the superposition amount of the modulation waves of the bridge arms to respectively obtain the final modulation wave of the first sub-bridge arm and the final modulation wave of the second sub-bridge arm, and further adjusting the output voltages of the first sub-bridge arm and the second sub-bridge arm to inhibit the circulating current between the parallel sub-bridge arms. Bridge arm current of two sub bridge arms is obtained to obtain bridge arm modulation wave superposition amount, the bridge arm modulation wave superposition amount is distributed according to different preset distribution proportions of specific devices to obtain final modulation waves of each sub bridge arm, and then output voltage of the sub bridge arms is adjusted to restrain circulation current between the parallel sub bridge arms.
Description
Technical Field
The invention relates to the technical field of flexible direct current transmission control, in particular to a bridge arm parallel MMC parallel sub-bridge arm current-sharing control method and device.
Background
The flexible direct-current transmission technology based on the Modular Multilevel Converter (MMC) has the advantages of independent and flexible control of active power and reactive power, no problem of commutation failure, no need of reactive power compensation, easy capacity expansion and the like, and is widely applied. In recent years, with the gradual landing of demonstration projects and the increasingly strengthened requirement of domestic large-scale energy transmission, the requirement of a system on the flexible direct current transmission capacity is continuously improved. As most conventional extra-high voltage direct currents are in the grade of +/-800 kV/8000MW, in order to better match existing or newly-built conventional extra-high voltage direct currents, an extra-high voltage direct current grid frame of +/-800 kV is constructed, and the flexible direct current system is increased to the grade of +/-800 kV/8000 MW. Under the requirement, the direct current of the system reaches 5000A level, and according to the topology and design of the conventional MMC, the peak value of the bridge arm current of the MMC is close to 5500A. However, the highest specification of the existing mature IGBT device in China is only 4500V/3000A, and the IGBT device does not meet the application occasions of high current, so that the popularization of the ultrahigh voltage high-capacity field of the flexible direct current technology is restricted to a certain extent.
Under the background that the level of the existing device is not broken through, the existing device is utilized to develop bridge arm parallel type MMC, the capacity of the converter is improved in a mode of parallel connection of bridge arms, and the method is a feasible scheme of compromise at present. According to the scheme, two sub-bridge arms with the same structure and parameters are connected in parallel to form one bridge arm of the MMC, the current stress of a single sub-bridge arm can be reduced by half, and the system requirements can be met by applying the existing 4500V/3000A IGBT device.
For the upper bridge arm and the lower bridge arm of each phase unit, although the two parallel sub-bridge arms have the same structure and parameter requirements, the difference of the production and the manufacture of components is inevitable, the output voltages of the two sub-bridge arms are still different, and further, the circulation current between the parallel sub-bridge arms is caused, is determined by the difference between the sub-bridge arms and the reactance value of the bridge arms, and is not negligible when the difference is large, so that the long-time overload operation and even overcurrent of the individual sub-bridge arms are easily caused, and the safe and stable operation of equipment is threatened. Therefore, measures are needed to effectively inhibit the circulating current between the parallel sub-bridge arms.
Disclosure of Invention
The invention aims to provide a bridge arm parallel MMC parallel sub-bridge arm current sharing control method and device.
In order to solve the above technical problem, a first aspect of the embodiments of the present invention provides a method for controlling current sharing of parallel sub-bridge arms of a bridge arm parallel MMC, where an upper bridge arm and a lower bridge arm of each phase in the bridge arm parallel MMC are formed by connecting a first sub-bridge arm and a second sub-bridge arm that have the same structure in parallel, and the method includes the following steps:
acquiring a circulating current value between the parallel sub bridge arms of the first sub bridge arm and the second sub bridge arm;
calculating the superposition amount of the modulation waves of the bridge arms through damping coefficients according to the current values of the loop currents between the bridge arms of the parallel sub-bridge arms;
distributing the superposition amount of the modulation waves of the bridge arms according to a preset distribution proportion, and obtaining the superposition amount of the modulation waves of the first sub-bridge arm and the superposition amount of the modulation waves of the second sub-bridge arm after amplitude limiting;
and combining the original modulation waves of the bridge arms to respectively obtain the final modulation wave of the first sub-bridge arm and the final modulation wave of the second sub-bridge arm, and further adjusting the output voltages of the first sub-bridge arm and the second sub-bridge arm to inhibit the circulating current between the parallel sub-bridge arms.
Further, the obtaining of the current value of the loop current between the parallel sub-bridge arms of the first sub-bridge arm and the second sub-bridge arm includes:
obtaining a bridge arm current of the first sub-bridge arm;
obtaining bridge arm current of the secondary bridge arm II;
and calculating half of the difference between the bridge arm current of the first sub-bridge arm and the bridge arm current of the second sub-bridge arm, namely calculating the current value of the loop current between the parallel sub-bridge arms.
Further, the preset distribution proportion includes a first preset proportion value and a second preset proportion value, where the first preset proportion value is a proportion value of the bridge arm modulation wave superposition amount distributed by the first sub-bridge arm, and the second preset proportion value is a proportion value of the bridge arm modulation wave superposition amount distributed by the first sub-bridge arm;
the sum of the first preset proportion value and the second preset proportion value is 100%.
Further, the combining the original modulation wave of the bridge arm to obtain the final modulation wave of the first sub-bridge arm and the final modulation wave of the second sub-bridge arm respectively includes:
adding the bridge arm modulation wave superposition quantity with the modulation wave superposition quantity of the first sub-bridge arm to obtain a final modulation wave of the first sub-bridge arm;
and subtracting the superposition quantity of the modulation wave of the second sub-bridge arm from the superposition quantity of the modulation wave of the second sub-bridge arm to obtain the final modulation wave of the second sub-bridge arm.
Accordingly, a second aspect of the embodiments of the present invention provides a bridge arm parallel MMC parallel sub-bridge arm current-sharing control device, where an upper bridge arm and a lower bridge arm of each phase in the bridge arm parallel MMC are formed by connecting a first sub-bridge arm and a second sub-bridge arm that have the same structure in parallel, and the device includes:
the acquisition module is used for acquiring the circulating current value between the parallel sub bridge arms of the first sub bridge arm and the second sub bridge arm;
the calculation module is used for calculating the superposition amount of the modulation waves of the bridge arms through damping coefficients according to the current values of the circulation currents among the parallel sub-bridge arms;
the distribution module is used for distributing the superposition amount of the modulation waves of the bridge arms according to a preset distribution proportion and obtaining the superposition amount of the modulation waves of the first sub-bridge arm and the superposition amount of the modulation waves of the second sub-bridge arm after amplitude limiting processing;
and the control module is used for combining the original modulation waves of the bridge arms to respectively obtain the final modulation wave of the first sub-bridge arm and the final modulation wave of the second sub-bridge arm so as to further adjust the output voltages of the first sub-bridge arm and the second sub-bridge arm to inhibit the circulating current between the parallel sub-bridge arms.
Further, the obtaining module comprises: the device comprises a first acquisition unit, a second acquisition unit and a first calculation unit;
the first obtaining unit is used for obtaining the bridge arm current of the first sub-bridge arm;
the second obtaining unit is used for obtaining bridge arm current of the second sub-bridge arm;
the first calculating unit is used for calculating half of the difference between the bridge arm current of the first sub-bridge arm and the bridge arm current of the second sub-bridge arm, namely the current value of the loop current between the parallel sub-bridge arms.
Further, the preset distribution proportion includes a first preset proportion value and a second preset proportion value, where the first preset proportion value is a proportion value of the bridge arm modulation wave superposition amount distributed by the first sub-bridge arm, and the second preset proportion value is a proportion value of the bridge arm modulation wave superposition amount distributed by the first sub-bridge arm;
the sum of the first preset proportion value and the second preset proportion value is 100%.
Further, the control module includes: the device comprises a first superposition unit, a second superposition unit and a control unit;
the first superposition unit is used for adding the original modulation wave of the bridge arm and the superposition quantity of the modulation wave of the first sub-bridge arm to obtain a final modulation wave of the first sub-bridge arm;
the second superposition unit is used for subtracting the superposition quantity of the original modulation wave of the bridge arm and the modulation wave of the second sub-bridge arm to obtain a final modulation wave of the second sub-bridge arm;
the control unit is used for adjusting the output voltages of the first sub-bridge arm and the second sub-bridge arm so as to inhibit the circulating current between the parallel sub-bridge arms.
Accordingly, a third aspect of an embodiment of the present invention provides an electronic device, including: at least one processor; and a memory coupled to the at least one processor; the storage stores instructions which can be executed by the processor, and the instructions are executed by the processor, so that the at least one processor executes the bridge arm parallel MMC parallel sub-bridge arm current-sharing control method.
Accordingly, a fourth aspect of the embodiments of the present invention provides a computer-readable storage medium, on which computer instructions are stored, and the instructions, when executed by a processor, implement the bridge arm parallel MMC parallel sub-bridge arm current sharing control method described above.
The technical scheme of the embodiment of the invention has the following beneficial technical effects:
bridge arm current of the two sub-bridge arms is obtained to obtain bridge arm modulation wave superposition amount, the bridge arm modulation wave superposition amount is distributed according to a preset distribution proportion of a specific device to obtain final modulation waves of the two sub-bridge arms, and output voltage of the sub-bridge arms is adjusted to inhibit circulation current between the parallel sub-bridge arms.
Drawings
FIG. 1 is a schematic diagram of a bridge arm parallel MMC in the prior art;
FIG. 2 is a flowchart of a bridge arm parallel MMC parallel sub-bridge arm current-sharing control method provided by the embodiment of the invention;
FIG. 3 is a schematic diagram of a bridge arm parallel MMC parallel sub-bridge arm current-sharing control method provided by the embodiment of the invention;
FIG. 4 is a block diagram of a bridge arm parallel MMC parallel sub-bridge arm current-sharing control device provided in an embodiment of the present invention;
FIG. 5 is a block diagram of an acquisition module provided by embodiments of the present invention;
fig. 6 is a block diagram of a control module according to an embodiment of the present invention.
Reference numerals:
1. the device comprises an acquisition module 11, a first acquisition unit 12, a second acquisition unit 13, a first calculation unit 2, a calculation module 3, an allocation module 4, a control module 41, a first superposition unit 42, a second superposition unit 43 and a control unit.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings in conjunction with the following detailed description. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.
Fig. 1 is a schematic diagram of a bridge arm parallel type MMC in the prior art.
Referring to fig. 1, each phase of the bridge arm parallel type MMC is formed by connecting two identical sub-bridge arms in parallel, each sub-bridge arm comprises a plurality of cascade sub-modules and a bridge arm reactor, and the sub-modules are in a half-bridge sub-module topology and a full-bridge sub-module topology.
Fig. 2 is a flowchart of a bridge arm parallel type MMC parallel sub-bridge arm current-sharing control method provided by the embodiment of the invention.
Fig. 3 is a schematic diagram of a bridge arm parallel type MMC parallel sub-bridge arm current-sharing control method provided by the embodiment of the invention.
Referring to fig. 2 and fig. 3, a first aspect of the embodiments of the present invention provides a method for current sharing control of parallel sub-bridge arms of a bridge arm parallel MMC, where an upper bridge arm and a lower bridge arm of each phase in the bridge arm parallel MMC are formed by connecting a first sub-bridge arm and a second sub-bridge arm in parallel with the same structure and parameters, and the method includes the following steps:
s100, acquiring a circulating current value i between the parallel sub-bridge arms of the first sub-bridge arm and the second sub-bridge armloop_arm12。
S200, according to the current circulation between the parallel sub-bridge armsFlow value iloop_arm12Calculating the superposition quantity delta m of the bridge arm modulation wave through the damping coefficient Krloop_arm12。
S300, according to a preset distribution proportion, overlapping quantity delta m of bridge arm modulation wavesloop_arm12Distributing and carrying out amplitude limiting processing to obtain the modulation wave superposition quantity delta m of the first sub-bridge armloop_arm1The modulation wave superposition quantity delta m of the secondary bridge arm IIloop_arm2。
S400, combining the original modulation wave m of the bridge armarmRespectively obtaining the final modulation wave m of the sub bridge arm Iarm_1Final modulation wave m of the second bridge armarm_2And further adjusting the output voltage of the first sub-bridge arm and the second sub-bridge arm to inhibit the circulating current between the parallel sub-bridge arms.
Further, in step S100, obtaining a current value of a loop between the parallel sub-bridge arms of the first sub-bridge arm and the second sub-bridge arm specifically includes the following steps:
s110, obtaining bridge arm current i of the first sub-bridge armarm_1。
S120, obtaining bridge arm current i of the second sub-bridge armarm_2。
S130, calculating bridge arm current i of the first sub-bridge armarm_1Bridge arm current i of secondary bridge arm IIarm_2Half of the difference, i.e. the value of the circulating current i between the parallel sub-armsloop_arm12。
Further, in step S300, the preset distribution ratio includes a first preset ratio value and a second preset ratio value, where the first preset ratio value is a bridge arm modulation wave superposition amount Δ m distributed by the first sub-bridge armloop_arm12The second preset proportional value is the proportional value of the bridge arm modulation wave superposition quantity delta mloop _ arm12 distributed by the sub-bridge arms; the sum of the first preset proportion value and the second preset proportion value is 100%.
Specifically, the distribution according to the preset distribution ratio in the above scheme may be that two sub-arms are respectively distributed by half, that is, both coefficients s1 and s2 are 0.5, or one sub-arm is fully distributed, and the other sub-arm is not distributed, that is, s1 is equal to 1, s2 is equal to 0, or s1 is equal to 0, and s2 is equal to 1, which may specifically be determined according to the difference between the two sub-arms.
Further, in step S400, the original bridge arm modulated wave m is combinedarmRespectively obtaining the final modulation waves m of the sub bridge arms Iarm_1Final modulation wave m of the second bridge armarm_2The method comprises the following steps:
s410, overlapping the bridge arm modulation wave by marmThe superposition quantity delta m of the modulation wave of the first sub-bridge armloop_arm1Adding to obtain the final modulation wave m of the sub bridge arm Iarm_1；
S420, bridge arm modulation wave superposition quantity marmThe superposition quantity delta m of the modulation wave of the second sub-bridge armloop_arm2Subtracting to obtain the final modulation wave m of the second sub-bridge armarm_2。
According to the bridge arm parallel MMC parallel sub-bridge arm current sharing control method, bridge arm currents of two sub-bridge arms are obtained, and further bridge arm modulation wave superposition quantity delta mloop_arm12And distributing the bridge arms according to a preset distribution proportion of a specific device to obtain final modulation waves of the two sub-bridge arms, and further adjusting output voltages of the sub-bridge arms to inhibit the problem of circumfluence between the sub-bridge arms of the bridge arm parallel type MMC caused by the difference of the two parallel sub-bridge arms and improve the operation reliability of the bridge arm parallel type MMC.
Fig. 4 is a block diagram of a bridge arm parallel type MMC parallel sub-bridge arm current-sharing control device provided in an embodiment of the present invention.
Accordingly, referring to fig. 4, a second aspect of the embodiment of the present invention provides a bridge arm parallel MMC parallel sub-bridge arm current-sharing control device, where an upper bridge arm and a lower bridge arm of each phase in the bridge arm parallel MMC are formed by connecting a first sub-bridge arm and a second sub-bridge arm with the same structure in parallel, and the device includes: the device comprises an acquisition module 1, a calculation module 2, a distribution module 3 and a control module 4.
Specifically, the obtaining module 1 is used for obtaining a circulating current value i between parallel sub-bridge arms of the first sub-bridge arm and the second sub-bridge armloop_arm12(ii) a The calculation module 2 is used for calculating a current value i according to the current circulating value between the parallel sub-bridge armsloop_arm12Calculating the superposition quantity delta m of the bridge arm modulation wave through the damping coefficient Krloop_arm12(ii) a The distribution module 3 is used for superposing the quantity delta m of the bridge arm modulation waves according to the preset distribution proportionloop_arm12Is distributed and passes through the clipping partObtaining the modulation wave superposition quantity delta m of the first sub-bridge armloop_arm1The modulation wave superposition quantity delta m of the secondary bridge arm IIloop_arm2(ii) a The control module 4 is used for combining the original modulation wave m of the bridge armarmRespectively obtaining the final modulation wave m of the sub bridge arm Iarm_1Final modulation wave m of the second bridge armarm_2And further adjusting the output voltage of the first sub-bridge arm and the second sub-bridge arm to inhibit the circulating current between the parallel sub-bridge arms.
Fig. 5 is a block diagram of an acquisition module according to an embodiment of the present invention.
Further, referring to fig. 5, the obtaining module 1 includes: a first acquisition unit 11, a second acquisition unit 12 and a first calculation unit 13. The first obtaining unit 11 is configured to obtain a bridge arm current i of the first sub-bridge armarm_1(ii) a The second obtaining unit 12 is configured to obtain a bridge arm current i of the sub-bridge arm twoarm_2(ii) a The first calculating unit 13 is used for calculating a bridge arm current i of the first bridge armarm_1Bridge arm current i of secondary bridge arm IIarm_2Half of the difference, i.e. the value of the circulating current i between the parallel sub-armsloop_arm12。
Further, the preset distribution proportion comprises a first preset proportion value and a second preset proportion value, wherein the first preset proportion value is the bridge arm modulation wave superposition quantity Deltam distributed by the first sub-bridge armloop_arm12The second preset proportional value is the superposed quantity delta m of the bridge arm modulation waves distributed in the sub-bridge armsloop_arm12The proportional value of (c). The sum of the first preset proportion value and the second preset proportion value is 100%.
Specifically, the distribution according to the preset distribution ratio in the above scheme may be that two sub-arms are respectively distributed by half, that is, both coefficients s1 and s2 are 0.5, or one sub-arm is fully distributed, and the other sub-arm is not distributed, that is, s1 is equal to 1, s2 is equal to 0, or s1 is equal to 0, and s2 is equal to 1, which may specifically be determined according to the difference between the two sub-arms.
Fig. 6 is a block diagram of a control module according to an embodiment of the present invention.
Further, referring to fig. 6, the control module 4 includes: a first superimposing unit 41, a second superimposing unit 42 and a control unit 43. For the first superimposing unit 41In the original modulation wave m of the bridge armarmThe superposition quantity delta m of the modulation wave of the first sub-bridge armloop_arm1Adding to obtain the final modulation wave m of the sub bridge arm Iarm_1(ii) a The second superposition unit 42 is used for modulating the original bridge arm modulation wave marmThe superposition quantity delta m of the modulation wave of the second sub-bridge armloop_arm2Subtracting to obtain the final modulation wave m of the second sub-bridge armarm_2(ii) a The control unit 43 is configured to adjust output voltages of the first sub-bridge arm and the second sub-bridge arm to suppress a circulating current between the parallel sub-bridge arms.
According to the bridge arm parallel MMC parallel sub-bridge arm current sharing control device, bridge arm modulation wave superposition quantity is obtained by obtaining bridge arm currents of two sub-bridge arms and is distributed according to the preset distribution proportion of the specific device, final modulation waves of the two sub-bridge arms are obtained, the output voltage of the sub-bridge arms is further adjusted, the problem of circulation between the sub-bridge arms of the bridge arm parallel MMC due to the difference of the two parallel sub-bridge arms is solved, and the running reliability of the bridge arm parallel MMC is improved.
Accordingly, a third aspect of an embodiment of the present invention provides an electronic device, including: at least one processor; and a memory coupled to the at least one processor; the storage stores instructions which can be executed by the processor, and the instructions are executed by the processor, so that the at least one processor executes the bridge arm parallel MMC parallel sub-bridge arm current-sharing control method.
Accordingly, a fourth aspect of the embodiments of the present invention provides a computer-readable storage medium, on which computer instructions are stored, and the instructions, when executed by a processor, implement the bridge arm parallel MMC parallel sub-bridge arm current sharing control method described above.
The embodiment of the invention aims to protect a bridge arm parallel MMC parallel sub-bridge arm current-sharing control method and a device, wherein the method comprises the following steps: acquiring a circulating current value between parallel sub-bridge arms of the sub-bridge arm I and the sub-bridge arm II; calculating the superposition amount of the modulation waves of the bridge arms through damping coefficients according to the current values of the loop currents between the parallel sub-bridge arms; distributing the superposition amount of the modulation waves of the bridge arms according to a preset distribution proportion, and obtaining the superposition amount of the modulation waves of the first sub-bridge arm and the superposition amount of the modulation waves of the second sub-bridge arm after amplitude limiting; and combining the superposition amount of the modulation waves of the bridge arms to respectively obtain the final modulation wave of the first sub-bridge arm and the final modulation wave of the second sub-bridge arm, and further adjusting the output voltages of the first sub-bridge arm and the second sub-bridge arm to inhibit the circulating current between the parallel sub-bridge arms. The technical scheme has the following effects:
bridge arm current of the two sub bridge arms is obtained to obtain bridge arm modulation wave superposition quantity, the bridge arm modulation wave superposition quantity is distributed according to a preset distribution proportion of a specific device to obtain final modulation waves of the two sub bridge arms, and output voltage of the sub bridge arms is further adjusted to inhibit the problem of circulation between the sub bridge arms of the bridge arm parallel type MMC caused by the difference of the two parallel sub bridge arms, and the running reliability of the bridge arm parallel type MMC is improved.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application 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 application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams 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.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (10)
1. A bridge arm parallel type MMC parallel sub-bridge arm current sharing control method is characterized in that an upper bridge arm and a lower bridge arm of each phase in the bridge arm parallel type MMC are formed by connecting a sub-bridge arm I and a sub-bridge arm II which have the same structure and parameters in parallel, and the method comprises the following steps:
acquiring a circulating current value between the parallel sub bridge arms of the first sub bridge arm and the second sub bridge arm;
calculating the superposition amount of the modulation waves of the bridge arms through damping coefficients according to the current values of the loop currents between the bridge arms of the parallel sub-bridge arms;
distributing the superposition amount of the modulation waves of the bridge arms according to a preset distribution proportion, and obtaining the superposition amount of the modulation waves of the first sub-bridge arm and the superposition amount of the modulation waves of the second sub-bridge arm after amplitude limiting;
and combining the original modulation waves of the bridge arms to respectively obtain the final modulation wave of the first sub-bridge arm and the final modulation wave of the second sub-bridge arm, and further adjusting the output voltages of the first sub-bridge arm and the second sub-bridge arm to inhibit the circulating current between the parallel sub-bridge arms.
2. The bridge arm parallel MMC parallel sub-bridge arm current sharing control method of claim 1, wherein obtaining a current value of a loop current between parallel sub-bridge arms of the first sub-bridge arm and the second sub-bridge arm comprises:
obtaining a bridge arm current of the first sub-bridge arm;
obtaining bridge arm current of the secondary bridge arm II;
and calculating half of the difference between the bridge arm current of the first sub-bridge arm and the bridge arm current of the second sub-bridge arm, namely calculating the current value of the loop current between the parallel sub-bridge arms.
3. The bridge arm parallel MMC parallel sub-bridge arm current-sharing control method of claim 1,
the preset distribution proportion comprises a first preset proportion value and a second preset proportion value, wherein the first preset proportion value is the proportion value of the bridge arm modulation wave superposition amount distributed by the first sub-bridge arm, and the second preset proportion value is the proportion value of the bridge arm modulation wave superposition amount distributed by the second sub-bridge arm;
the sum of the first preset proportion value and the second preset proportion value is 100%.
4. The bridge arm parallel MMC parallel sub-bridge arm current-sharing control method of claim 1, wherein the combining the original modulation wave of the bridge arm to obtain the final modulation wave of the first sub-bridge arm and the final modulation wave of the second sub-bridge arm respectively comprises:
adding the original modulation wave of the bridge arm and the superposition amount of the modulation wave of the first sub-bridge arm to obtain a final modulation wave of the first sub-bridge arm;
and subtracting the superposition quantity of the original modulation wave of the bridge arm and the modulation wave of the second sub-bridge arm to obtain the final modulation wave of the second sub-bridge arm.
5. The utility model provides a parallelly connected sub-bridge arm current-sharing control device of bridge arm parallel MMC which characterized in that, each looks upper bridge arm and lower bridge arm in bridge arm parallel MMC by the structure and the parameter the same sub-bridge arm one with the sub-bridge arm two parallelly connected constitutes, includes:
the acquisition module is used for acquiring the circulating current value between the parallel sub bridge arms of the first sub bridge arm and the second sub bridge arm;
the calculation module is used for calculating the superposition amount of the modulation waves of the bridge arms through damping coefficients according to the current values of the circulation currents among the parallel sub-bridge arms;
the distribution module is used for distributing the superposition amount of the modulation waves of the bridge arms according to a preset distribution proportion and obtaining the superposition amount of the modulation waves of the first sub-bridge arm and the superposition amount of the modulation waves of the second sub-bridge arm after amplitude limiting processing;
and the control module is used for combining the original modulation waves of the bridge arms to respectively obtain the final modulation wave of the first sub-bridge arm and the final modulation wave of the second sub-bridge arm so as to further adjust the output voltages of the first sub-bridge arm and the second sub-bridge arm to inhibit the circulating current between the parallel sub-bridge arms.
6. The bridge arm parallel MMC parallel sub-bridge arm current-sharing control device of claim 5, wherein the obtaining module comprises: the device comprises a first acquisition unit, a second acquisition unit and a first calculation unit;
the first obtaining unit is used for obtaining the bridge arm current of the first sub-bridge arm;
the second obtaining unit is used for obtaining bridge arm current of the second sub-bridge arm;
the first calculating unit is used for calculating half of the difference between the bridge arm current of the first sub-bridge arm and the bridge arm current of the second sub-bridge arm, namely the current value of the loop current between the parallel sub-bridge arms.
7. The bridge arm parallel MMC parallel sub-bridge arm current-sharing control device of claim 5,
the preset distribution proportion comprises a first preset proportion value and a second preset proportion value, wherein the first preset proportion value is the proportion value of the bridge arm modulation wave superposition amount distributed by the first sub-bridge arm, and the second preset proportion value is the proportion value of the bridge arm modulation wave superposition amount distributed by the second sub-bridge arm;
the sum of the first preset proportion value and the second preset proportion value is 100%.
8. The bridge arm parallel MMC parallel sub-bridge arm current-sharing control device of claim 5, wherein the control module comprises: the device comprises a first superposition unit, a second superposition unit and a control unit;
the first superposition unit is used for adding the original modulation wave of the bridge arm and the superposition quantity of the modulation wave of the first sub-bridge arm to obtain a final modulation wave of the first sub-bridge arm;
the second superposition unit is used for subtracting the superposition quantity of the original modulation wave of the bridge arm and the modulation wave of the second sub-bridge arm to obtain a final modulation wave of the second sub-bridge arm;
the control unit is used for adjusting the output voltages of the first sub-bridge arm and the second sub-bridge arm so as to inhibit the circulating current between the parallel sub-bridge arms.
9. An electronic device, comprising: at least one processor; and a memory coupled to the at least one processor; wherein the memory stores instructions executable by the one processor to cause the at least one processor to perform the bridge arm parallel MMC parallel sub-bridge arm current sharing control method of any of claims 1-4.
10. A computer readable storage medium having stored thereon computer instructions which, when executed by a processor, implement the bridge arm parallel MMC parallel sub-bridge arm current sharing control method of any of claims 1-4.
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| CN116054531B (en) * | 2022-12-15 | 2023-07-07 | 山东大学 | Mixed MMC bridge arm internal modulation wave distribution control method and system |
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