CN108306318B - Symmetrical energy storage system based on modular multilevel converter - Google Patents

Symmetrical energy storage system based on modular multilevel converter Download PDF

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Publication number
CN108306318B
CN108306318B CN201810025043.3A CN201810025043A CN108306318B CN 108306318 B CN108306318 B CN 108306318B CN 201810025043 A CN201810025043 A CN 201810025043A CN 108306318 B CN108306318 B CN 108306318B
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energy storage
storage system
bridge
circuit
input
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CN108306318A (en
Inventor
杨晓峰
郑琼林
李泽杰
薛尧
游小杰
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Beijing Jiaotong University
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Beijing Jiaotong University
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Classifications

    • 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
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • 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
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • 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
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H02M3/33592—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
    • 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
    • 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
    • H02M1/0067—Converter structures employing plural converter units, other than for parallel operation of the units on a single load
    • H02M1/007—Plural converter units in cascade

Abstract

The invention relates to a symmetrical energy storage system based on a modular multilevel converter, which comprises the modular multilevel converter, an energy storage system interface p2, an energy storage system interface n2, an isolated DC/DC circuit, an energy storage unit, a positive high-voltage direct-current bus, a self-leaded positive high-voltage direct-current bus, a negative high-voltage direct-current bus and a self-leaded negative high-voltage direct-current bus; the k-phase input end of the modular multilevel converter is connected with k-phase high-voltage alternating current, the output end of the modular multilevel converter is respectively connected with an energy storage system interface p2 and an energy storage system interface n2, the output end of the energy storage system interface p2 and the output end of the energy storage system interface n2 are connected with the input end of the isolation type DC/DC circuit, and the output end of the isolation type DC/DC circuit is connected with the energy storage unit. The symmetrical energy storage system provided by the invention overcomes the defects of unbalanced energy distribution of the traditional distributed energy storage units and uneven energy on the feedback network side of the traditional centralized series energy storage units, and provides a high-quality, safe and reliable symmetrical energy storage system for a power system.

Description

Symmetrical energy storage system based on modular multilevel converter
Technical Field
The invention relates to a symmetrical energy storage system, in particular to a symmetrical fully-centralized and symmetrical centralized energy storage system based on a modular multilevel converter in the technical field of power electronics.
Background
With the increasing of new energy grid-connected demand and system capacity, the intermittent and fluctuating property of the system under the influence of environment can cause the voltage on the grid side to fluctuate more, and the system has more negative influence on the safe and reliable operation of the power grid. In order to inhibit the grid-connected fluctuation of new energy power generation, an energy storage system is added to be an effective solution, so that the grid-side energy is buffered, the grid-side energy fluctuation is reduced, the electric energy quality is improved, and the safe and reliable operation of a power supply system of a power grid is guaranteed.
In order to relieve the energy crisis and solve the large-scale demand of people on electric power, new energy grid-connected application needs to be expanded urgently, and high-voltage direct-current power transmission has a larger application prospect compared with traditional alternating-current power transmission. Therefore, new energy is incorporated into the power grid, the requirement on the safety and reliability of high-voltage direct-current transmission becomes stricter, and a Modular Multilevel Converter (MMC) is widely applied to various fields such as high-voltage direct-current transmission and new energy grid connection due to the advantages of high modular structure, public direct-current bus, high equivalent switching frequency and the like, so that the safety and reliability of the system are greatly improved.
In recent years, the MMC energy storage technology can be divided into centralized parallel energy storage and distributed parallel energy storage according to the topology application form, and can be divided into non-isolated energy storage and isolated energy storage according to whether the energy storage is isolated. In the traditional centralized parallel energy storage, an Energy Storage Unit (ESU) is directly connected in parallel to a high-voltage direct current side, so that the structure is simple, but the voltage of each submodule is unbalanced, so that the energy feedback network side is not uniform. Traditional distributed energy storage system distributes the energy storage unit in each submodule piece of MMC, needs to carry out complicated balanced control to the charged state of energy storage unit in each submodule piece, and the energy storage unit of distributing type brings great inconvenience for its installation, maintenance, change, management, and along with the increase of system capacity, MMC submodule piece figure need increase, and voltage unbalance between its submodule piece is more serious, leads to its each module voltage balance more difficult to control. Therefore, improvements based on centralized energy storage systems have been reluctant.
Although the non-isolated energy storage has no isolation transformer, the system cost can be reduced, in the middle and high voltage field, for the purposes of controlling safety and prolonging the service life of the system, a high-frequency isolation transformer device needs to be added to form an isolated energy storage system. Therefore, the symmetrical energy storage system based on the modular multilevel converter avoids the defects of unbalanced energy distribution of the traditional distributed energy storage units and uneven energy on the feedback network side of the traditional centralized series energy storage units, and relates to symmetrical fully-centralized and symmetrical centralized energy storage systems based on the modular multilevel converter.
Disclosure of Invention
The invention aims to overcome the defects of complex control, unbalanced energy distribution, inconvenient assembly, maintenance and energy storage unit management and uneven energy on the feedback network side of the traditional centralized energy storage unit in the traditional distributed energy storage unit, provides a symmetrical fully centralized and symmetrical centralized energy storage system based on a modular multilevel converter, and provides an energy storage system with high quality, safe operation and even energy feedback network side for a power system.
In order to achieve the above purposes, the technical scheme adopted by the invention is as follows:
a modular multilevel converter based symmetric energy storage system comprising: the system comprises a modular multilevel converter 1, an energy storage system interface p2, an energy storage system interface n2, an isolated DC/DC circuit 3, an energy storage unit 4, a positive high-voltage direct-current bus, a self-induced positive high-voltage direct-current bus, a negative high-voltage direct-current bus and a self-induced negative high-voltage direct-current bus;
the modular multilevel converter 1 is composed of k phases and 2k bridge arms; each phase of bridge arm comprises an upper bridge arm and a lower bridge arm; each phase of upper bridge arm is composed of upper bridge arm inductor LpiAnd submodules 2 to n are connected in series, and each phase of lower bridge arm is composed of a lower bridge arm inductor LniAnd submodules n +1 to 2n-1 are connected in series;
the energy storage system interface p2 includes: energy storage system submodule SMPiEnergy storage System submodule SMPiAre connected in parallel; the energy storage system submodule is SMPiThe method comprises the following steps: upper power tube Tp2i-1And lower power tube Tp2iUpper power tube Tp2i-1And lower power tube Tp2iAre connected in series;
the energy storage system interface n2 includes: energy storage system submodule SMNiEnergy storage system submodule SMNiAre connected in parallel; the energy storage system submodule SMNiThe method comprises the following steps: upper power tube Tn2i-1And a lower power tube Tn2iUpper power tube Tn2i-1And a lower power tube Tn2iAre connected in series;
the energy storage system submodule is SMPiBy passingUpper power tube Tp2i-1Connected with a positive high-voltage direct-current bus, and an energy storage system submodule SMPiThrough the lower power tube Tp2iIs connected with a self-guiding positive high-voltage direct current bus; the energy storage system submodule SMNiThrough an upper power tube Tn2i-1Connected with a self-induced negative high-voltage direct-current bus, and an energy storage system submodule SMNiThrough a lower power tube Tn2iIs connected with a negative high-voltage direct-current bus;
the k-phase input end of the modular multilevel converter 1 is connected with k-phase high-voltage alternating current, and the output end of each phase is connected with an energy storage system submodule SMPiThe input ends of the sub-modules are connected, and the lower output end of each phase is connected with the SMN sub-module of the energy storage systemiThe input ends of the two-way valve are connected;
the output end of the energy storage system interface p2 and the output end of the energy storage system interface n2 are respectively connected with the input end of the isolated DC/DC circuit 3, the output end of the isolated DC/DC circuit 3 is connected with the energy storage unit 4, wherein i is 1,2, · · k.
The sub-modules of the modular multilevel converter 1 have various different structures, and the half-bridge sub-modules are mature in engineering. The AC input end of the modular multilevel converter 1, namely the middle point of each phase bridge arm of k phases, is connected with high-voltage AC of k phases, and the terminal voltages are respectively usiWhere i ═ 1,2, · · k.
Preferably, the sub-module of the modular multilevel converter 1 mainly adopts a half-bridge sub-module, the half-bridge sub-module adopts two different access modes, the half-bridge sub-module comprises two power switch tubes and a capacitor, the half-bridge sub-modules in each phase of upper bridge arm are connected in series in a certain number, and one end of each half-bridge sub-module is connected with the energy storage system sub-module SMP sub-moduleiIs connected with the input end of the upper bridge arm inductor L, and the other end of the upper bridge arm inductor L is connected with the input end of the lower bridge arm inductor LpiConnecting; the half-bridge submodules in each phase of lower bridge arm are connected in series in a certain number, and one end of each half-bridge submodule is connected with the energy storage system submodule SMNiIs connected with the input end of the lower bridge arm inductor L, and the other end of the lower bridge arm inductor L is connected with the input end of the lower bridge arm inductor LniConnecting; the existing submodule structures such as a full-bridge submodule, a clamping type submodule, a reverse resistance type half-bridge submodule and the like can be correspondingly selected according to the actual working condition, the comprehensive consideration of the system cost, the fault ride-through capability and the like, wherein i is 1,2,···k。
preferably, the number of levels of the modular multilevel converter 1, the structures of the upper and lower bridge arm sub-modules of each phase, and the number of input alternating-current voltage phases can be adjusted according to the system capacity level, the system fault redundancy working mode, and the voltage-withstanding levels of the power switching tubes in the upper and lower bridge arm sub-modules of each phase.
Preferably, the energy storage system submodule is SMPiThe input end of the energy storage system interface P2 is connected with the output end of the submodule 2 of each phase upper bridge arm, the upper output end P and the lower output end P 'of the energy storage system interface P2 are respectively connected with the input end P and the input end P' of the isolated DC/DC circuit 3, and the energy storage system submodule SMN is connected with the output end of the submodule 2 of each phase upper bridge armiThe input end of the energy storage system interface N2 is connected with the output end of the submodule 2N-1 of each phase of lower bridge arm, the lower output end N and the upper output end N 'of the energy storage system interface N2 are respectively connected with the input end N and the input end N' of the isolated DC/DC circuit 3, wherein i is 1,2, · · k.
Preferably, the isolated DC/DC circuit 3 includes two input ports and one output port outside, and the isolated DC/DC circuit 3 includes 2 inverter sub-modules, 1 two-input one-output high-frequency transformer, and 1 rectifier sub-module inside; the inverter submodule adopts an H-bridge inverter circuit or a half-bridge inverter circuit, and the rectifier submodule adopts an H-bridge rectifier circuit or a Buck-Boost voltage-boosting circuit behind the H-bridge rectifier circuit; the input end P and the input end P 'of the isolated DC/DC circuit 3 are respectively connected with the upper output end P and the lower output end P' of the energy storage system interface P2, the input end N and the input end N 'of the isolated DC/DC circuit 3 are respectively connected with the lower output end N and the upper output end N' of the energy storage system interface N2, and the output end of the isolated DC/DC circuit 3 is connected with the input end of the energy storage unit 4, so that the fully centralized energy storage system I is formed.
Preferably, the isolated DC/DC circuit 3 includes two input ports and two output ports outside, and the isolated DC/DC circuit 3 includes 2 inverter sub-modules, 2 high-frequency transformers with one input and one output, and 2 rectifier sub-modules inside; the outside of the energy storage unit 4 comprises two input ports; the inverter submodule adopts an H-bridge inverter circuit or a half-bridge inverter circuit, and the rectifier submodule adopts an H-bridge rectifier circuit or a Buck-Boost voltage-boosting circuit after H-bridge rectification; an input end P and an input end P 'of the isolated DC/DC circuit 3 are respectively connected with an upper output end P and a lower output end P' of the energy storage system interface P2, an input end N and an input end N 'of the isolated DC/DC circuit 3 are respectively connected with a lower output end N and an upper output end N' of the energy storage system interface N2, and two output ends of the isolated DC/DC circuit 3 are respectively connected with two input ends of the energy storage unit 4, so that a symmetrical centralized energy storage system II is formed.
Preferably, the 2 inverter sub-modules in the fully centralized energy storage system i all adopt H-bridge inverter circuits, an input end of one of the H-bridge inverter circuits is connected with an output end of the energy storage system interface p2 through a parallel flying capacitor, an input end of the other H-bridge inverter circuit is connected with an output end of the energy storage system interface n2 through a parallel flying capacitor, output ends of the 2H-bridge inverter circuits are respectively connected with two input ends of two-input one-output high-frequency transformers, and output ends of the two-input one-output high-frequency transformers are connected with the H-bridge rectification circuit.
Preferably, the 2 inverter sub-modules in the fully centralized energy storage system i all adopt H-bridge inverter circuits, an input end of one of the H-bridge inverter circuits is connected with an output end of the energy storage system interface p2 through a parallel flying capacitor, an input end of the other H-bridge inverter circuit is connected with an output end of the energy storage system interface n2 through a parallel flying capacitor, output ends of the 2H-bridge inverter circuits are respectively connected with two input ends of two input-output high-frequency transformers, and output ends of the two input-output high-frequency transformers are connected with the H-bridge rectification circuit and then connected with the Buck-Boost voltage-boosting circuit.
Preferably, in the fully centralized energy storage system i, the 2 inverter sub-modules adopt half-bridge inverter circuits, two capacitors connected in series are connected in parallel at the input end of one half-bridge inverter circuit and then connected with the output end of the energy storage system interface p2, two capacitors connected in series are connected in parallel at the input end of the other half-bridge inverter circuit and then connected with the output end of the energy storage system interface n2, the output ends of the 2 half-bridge inverter circuits are respectively connected with two input ends of the two-input one-output high-frequency transformer, and the output ends of the two-input one-output high-frequency transformer are connected with the H-bridge rectifier circuit.
Preferably, the 2 inverter sub-modules in the symmetric centralized energy storage system ii all adopt H-bridge inverter circuits, an input end of one of the H-bridge inverter circuits is connected to an output end of the energy storage system interface p2 through a parallel flying capacitor, an input end of the other H-bridge inverter circuit is connected to an output end of the energy storage system interface n2 through a parallel flying capacitor, an output end of the H-bridge inverter circuit is connected to an input end of an input-output high-frequency transformer, and an output end of the input-output high-frequency transformer is connected to an H-bridge rectifier circuit.
Preferably, the 2 inverter sub-modules in the symmetric centralized energy storage system ii all adopt H-bridge inverter circuits, an input end of one of the H-bridge inverter circuits is connected to an output end of the energy storage system interface p2 through a parallel flying capacitor, an input end of the other H-bridge inverter circuit is connected to an output end of the energy storage system interface n2 through a parallel flying capacitor, an output end of the H-bridge inverter circuit is connected to an input end of an input-output high-frequency transformer, and an output end of the input-output high-frequency transformer is connected to the H-bridge rectifier circuit and then connected to the Buck-Boost voltage-boosting circuit.
Preferably, the 2 inverter sub-modules in the symmetrical centralized energy storage system ii all adopt half-bridge inverter circuits, an input end of one half-bridge inverter circuit is connected in parallel with two series-connected capacitors and then connected with an output end of an energy storage system interface p2, an input end of the other half-bridge inverter circuit is connected in parallel with two series-connected capacitors and then connected with an output end of an energy storage system interface n2, an output end of the half-bridge inverter circuit is connected with an input end of an input-output high-frequency transformer, and an output end of the input-output high-frequency transformer is connected with an H-bridge rectification circuit.
Preferably, the energy storage unit 4 is formed by connecting a plurality of energy storage batteries or super capacitors or other energy storage sub-units in series.
Due to the adoption of the technical scheme, the invention has the following advantages: the symmetrical energy storage system based on the modular multilevel converter overcomes the defects of complex control, inconvenient assembly, maintenance and battery management and uneven energy feedback of the traditional centralized energy storage unit to the network side by adopting a fully centralized and symmetrical centralized energy storage mode, and provides an energy storage system with high quality, safe operation and even energy feedback network side for a power system.
Drawings
The invention has the following drawings:
FIG. 1 is a schematic diagram of the overall structure of a symmetrical energy storage system according to the present invention;
FIG. 2 is a schematic diagram of various sub-module topologies of the modular multilevel converter of the present invention;
FIG. 3 is a schematic diagram of a fully centralized energy storage system according to the present invention;
FIG. 4 is a schematic diagram of a symmetrical centralized energy storage system according to the present invention;
FIG. 5 shows SMP in the interface p2 of the energy storage system according to the inventioniThe internal structure schematic diagram;
FIG. 6 shows SMN in the interface n2 of the energy storage system according to the present inventioniThe internal structure schematic diagram;
FIG. 7 is a schematic diagram of an internal structure of a fully centralized first isolated DC/DC circuit according to the present invention;
FIG. 8 is a schematic diagram of an internal structure of a fully centralized second isolated DC/DC circuit according to the present invention;
FIG. 9 is a schematic diagram of an internal structure of a fully-centralized third isolated DC/DC circuit according to the present invention;
FIG. 10 is a schematic diagram of an internal structure of a symmetrical centralized first isolated DC/DC circuit according to the present invention;
FIG. 11 is a schematic diagram of an internal structure of a symmetric centralized second isolated DC/DC circuit according to the present invention;
FIG. 12 is a schematic diagram of an internal structure of a third isolated DC/DC circuit with a symmetrical concentration according to the present invention;
FIG. 13 is a schematic diagram of an internal structure of a first energy storage unit according to the present invention;
FIG. 14 is a schematic diagram of an internal structure of a second energy storage unit according to the present invention;
in the figure:
2000-first half-bridge circuit 2001-first power switch tube
2002-first diode 2003-reverse resistance type power switch tube
2100-first capacitor 2200-first full bridge circuit
2300-hoop position type double submodule 2400-reverse resistance type half-bridge submodule
3000-second full bridge circuit 3100-two-input-one-output high-frequency transformer
3101-first input winding 3102-second input winding
3103 magnetic core one 3104 first output winding
3200-third full bridge circuit 3201-second power switch tube
3300-second capacitor 3330-fourth capacitor
3331 fourth half-bridge 3332 second inductor
3400-second half-bridge circuit 3500-first inductor
3600 third capacitor 3700 third half-bridge circuit
3800-one input-one output high frequency transformer 3801-third input winding
3802-core two 3803-second output winding
3900-fourth full bridge circuit 3901-third power switch tube
4001-battery energy storage monomer 4002-super capacitor energy storage monomer
1-modular multilevel converter 3-isolated DC/DC circuit
4-energy storage unit
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
As shown in fig. 1, the present invention provides a symmetrical energy storage system based on a modular multilevel converter, which comprises: the system comprises a modular multilevel converter 1, an energy storage system interface p2, an energy storage system interface n2, an isolated DC/DC circuit 3, an energy storage unit 4, a positive high-voltage direct-current bus, a self-induced positive high-voltage direct-current bus, a negative high-voltage direct-current bus and a self-induced negative high-voltage direct-current bus;
the modular multilevel converter 1 is composed of k phases and 2k bridge arms; each phase of bridge arm comprises an upper bridge arm and a lower bridge arm; each phase of upper bridge arm is composed of upper bridge arm inductor LpiAnd submodules 2 to niAre connected in series, and each phase of lower bridge arm is composed of a lower bridge arm inductor LniAnd submodules n +1 to 2n-1 are connected in series;
the energy storage system interface p2 includes: energy storage system submodule SMPiEnergy storage System submodule SMPiParallel connection, energy storage system submodule SMPiThe method comprises the following steps: upper power tube Tp2i-1And lower power tube Tp2iUpper power tube Tp2i-1And lower power tube Tp2iAre connected in series; (ii) a
The energy storage system interface n2 includes: energy storage system submodule SMNiEnergy storage system submodule SMNiParallel connection, energy storage system submodule SMNiThe method comprises the following steps: upper power tube Tn2i-1And a lower power tube Tn2iUpper power tube Tn2i-1And a lower power tube Tn2iAre connected in series;
the energy storage system submodule is SMPiThrough an upper power tube Tp2i-1Connected with a positive high-voltage direct-current bus, and an energy storage system submodule SMPiThrough the lower power tube Tp2iIs connected with a self-guiding positive high-voltage direct current bus; the energy storage system submodule SMNiThrough an upper power tube Tn2i-1Connected with a self-induced negative high-voltage direct-current bus, and an energy storage system submodule SMNiThrough a lower power tube Tn2iIs connected with a negative high-voltage direct-current bus;
the k-phase input end of the modular multilevel converter 1 is connected with k-phase high-voltage alternating current, and the output end of each phase is connected with an energy storage system submodule SMPiThe input ends of the sub-modules are connected, and the lower output end of each phase is connected with the SMN sub-module of the energy storage systemiIs connected with the input end of the power supply,
the output end of the energy storage system interface p2 and the output end of the energy storage system interface n2 are respectively connected with the input end of the isolated DC/DC circuit 3, the output end of the isolated DC/DC circuit 3 is connected with the energy storage unit 4, wherein i is 1,2, · · k.
In this embodiment, as shown in fig. 1, the sub-modules of the modular multilevel converter 1 have various different structures, and the half-bridge sub-modules are used more mature in engineering. The AC input end of the modular multilevel converter 1, namely the middle point of each phase bridge arm of k phases, is connected with high-voltage AC of k phases, and the terminal voltages are respectively usiThe number of levels of the modular multilevel converter 1, the structures of the upper bridge arm submodule and the lower bridge arm submodule of each phase and the number of phases of the input alternating-current voltage can be correspondingly adjusted according to the system capacity grade, the system fault redundancy working mode and the voltage-resistant grade of the power switch tube in the upper bridge arm submodule and the lower bridge arm submodule of each phase.
In this embodiment, as shown in fig. 2, the sub-modules of the modular multilevel converter 1 have various structures, and are half-bridge sub-modules (HBSM) which are mature in engineering application, as shown in fig. 2(a) and 2(b), the half-bridge sub-modules HBSM1 and HBSM2 adopt two different access modes, two half-bridge sub-modules, i.e., HBSM1 and HBSM2, are both formed by connecting a first half-bridge circuit 2000 and a first capacitor 2100 in parallel, the first half-bridge circuit 2000 is formed by connecting two first power switching tubes 2001 in series, two ends of a lower first power switching tube 2001 in the HBSM1 are connected to an upper sub-module terminal 101 and a lower sub-module terminal 102, and two ends of an upper first power switching tube 2001 in the HBSM2 are connected to the upper sub-module terminal 101 and the lower sub-module terminal 102. The first power switch 2001 is an igbt with an anti-parallel freewheeling diode (the power switch is not limited to such a switch, and may be an electric field effect transistor, silicon carbide, gallium nitride, etc. may be used instead according to different working conditions), and the number of output levels of the system and the operating state of the system may be controlled by controlling the switching in and switching out of each half-bridge sub-module.
The sub-module of the modular multilevel converter 1 has various structures, which is the second structure of the sub-module of the modular multilevel converter 1 in this embodiment, as shown in fig. 2(c), the sub-module is a full-bridge sub-module (FBSM), the full-bridge sub-module is formed by connecting a first full-bridge circuit 2200 and a first capacitor 2100 in parallel, the first full-bridge circuit 2200 is formed by connecting two first half-bridge circuits 2000 in parallel, and the number of output levels of the system and the operating state of the system can be controlled by controlling the input and the cut-off of each full-bridge sub-module. Compared with a half-bridge submodule, the half-bridge submodule has the greatest advantages of having fault blocking capability and high efficiency, and simultaneously, the cost is increased.
The sub-modules of the modular multilevel converter 1 have various structures, in this embodiment, the sub-modules of the modular multilevel converter 1 have a third structure, as shown in fig. 2(d), the sub-modules are clamp-type double sub-modules (CDSM), each clamp-type double sub-module 2300 is composed of five first power switch tubes 2001, two first diodes 2002 and two first capacitors 2100, the number of output levels of the system and the operation state of the system can be controlled by controlling the switching-in and switching-off of each clamp-type sub-module, and after the system is locked due to a short-circuit fault, the modular multilevel converter 1 composed of the clamp-type double sub-modules has a bidirectional blocking capability of a fault current.
The sub-module of the modular multilevel converter 1 has various structures, in this embodiment, the sub-module of the modular multilevel converter 1 has a fourth structure, as shown in fig. 2(e), the sub-module is a reverse blocking sub-module (RBSM), the reverse blocking sub-module 2400 is formed by connecting a first power switch 2001 and a reverse blocking power switch 2003 in series and then connecting the first capacitor 2100 in parallel, the reverse blocking power switch 2003 adopts two reverse blocking devices connected in parallel instead of a conventional switch device, so as to realize the fault blocking capability of the modular multilevel converter 1 without increasing a large cost, and the number of output levels of the system and the operation state of the system can be controlled by controlling the input and the removal of each reverse blocking sub-module,
the sub-modules of the modular multilevel converter 1 have various structures, and the sub-modules are not limited to the structures listed above, and other modules based on an enhanced reverse blocking sub-module, a bidirectional blocking sub-module, a hybrid dual sub-module, and the like can be applied to the energy storage system.
In this embodiment, as shown in fig. 3, an upper output end P and a lower output end P 'of the energy storage system interface P2 are correspondingly connected to an input end P and an input end P' of the isolated DC/DC circuit 3, an output end N and an output end N 'of the energy storage system interface N2 are correspondingly connected to an input end N and an input end N' of the isolated DC/DC circuit 3, and output ends 301 and 302 of the isolated DC/DC circuit 3 are respectively connected to input ends 401 and 402 of the energy storage unit 4. At the moment, the modularized multi-level converter 1, the energy storage system interface p2, the energy storage system interface n2, the isolated DC/DC circuit 3, the energy storage unit 4, the positive high-voltage direct-current bus, the self-induced positive high-voltage direct-current bus, the negative high-voltage direct-current bus and the self-induced negative high-voltage direct-current bus form a fully centralized energy storage system I based on the modularized multi-level converter.
In this embodiment, as shown in fig. 4, an upper output end P and a lower output end P 'of the energy storage system interface P2 are correspondingly connected to an input end P and an input end P' of the isolated DC/DC circuit 3P, a lower output end N and an upper output end N 'of the energy storage system interface N2 are correspondingly connected to an input end N and an input end N' of the isolated DC/DC circuit 3N, output ends 303 and 304 of the isolated DC/DC circuit 3P are connected to input ends 403 and 404 of the upper energy storage unit ESUP in the energy storage unit 4, and output ends 305 and 306 of the isolated DC/DC circuit 3N are connected to input ends 405 and 406 of the lower energy storage unit ESUN in the energy storage unit 4. At the moment, the modularized multi-level converter 1, the energy storage system interface p2, the energy storage system interface n2, the isolated DC/DC circuit 3, the energy storage unit 4, the positive high-voltage direct-current bus, the self-induced positive high-voltage direct-current bus, the negative high-voltage direct-current bus and the self-induced negative high-voltage direct-current bus form a symmetrical centralized energy storage system II based on the modularized multi-level converter.
In this embodiment, as shown in fig. 5, the energy storage system submodule SMP in the energy storage system interface p2iA first half-bridge circuit 2000 structure is adopted, which is composed of three terminals, an input terminal is a middle input terminal 201, and an output terminal is an upper output terminal 202 and a lower output terminal 203. The middle input terminal 201 is connected with the upper output end of the submodule 2 of the modular multilevel converter 1, the upper output terminal 202 is connected with the positive high-voltage direct current bus, and the lower input terminal is connected with the positive high-voltage direct current busThe output terminal 203 is connected to a self-leaded positive high voltage dc bus. All energy storage system submodule SMPiThe modules together form an energy storage system interface P2, the output ends of which are an upper output end P and a lower output end P', and the output ends of which are connected with the corresponding interfaces of the isolated DC/DC circuit 3, wherein i is 1,2, · · k.
In this embodiment, as shown in fig. 6, the energy storage system submodule SMN in the energy storage system interface n2iA first half-bridge circuit 2000 structure is adopted, which is composed of three terminals, an input terminal is a middle input terminal 204, and an output terminal is an upper output terminal 205 and a lower output terminal 206. The middle input terminal 204 is connected with the lower output end of the submodule 2n-1 of the modular multilevel converter 1, the upper output terminal 205 is connected with a self-induced negative high-voltage direct-current bus, and the lower output terminal 206 is connected with a negative high-voltage direct-current bus. All energy storage system sub-modules SMNiThe modules together form an energy storage system interface N2, the output ends of which are an upper output end N' and a lower output end N, and the output ends of which are connected with corresponding interfaces of the isolated DC/DC circuit 3, wherein i is 1,2, · · k.
In this embodiment, as shown in fig. 7, the isolated DC/DC circuit 3 is an isolated DC/DC circuit of a fully centralized energy storage system i, where the isolated DC/DC circuit 3 includes two input ports and one output port outside. The isolated DC/DC circuit 3 includes various structures, and in this embodiment, is a first isolated DC/DC circuit, and is composed of two second full-bridge circuits 3000, a two-input one-output high-frequency transformer 3100, a third full-bridge circuit 3200, and a second capacitor 3300. The second full-bridge circuit 3000 includes four first power switch tubes 2001, the two-input one-output high-frequency transformer 3100 includes a first input winding 3101, a second input winding 3102, a first output winding 3104 and a first magnetic core 3103, the third full-bridge circuit 3200 includes four second power switch tubes 3201, the second power switch tubes 3201 are insulated gate bipolar transistors including anti-parallel freewheeling diodes, and the second power switch tubes 3201 are different from the first power switch tubes 2001 in device withstand voltage and current parameters. In the two second full-bridge circuits 3000, the input terminal 13 is connected to the upper output terminal P of the energy storage system interface P2, the input terminal 14 is connected to the lower output terminal P 'of the energy storage system interface P2, the input terminal 23 is connected to the upper output terminal N' of the energy storage system interface N2, and the input terminal 24 is connected to the lower output terminal N of the energy storage system interface N2. The alternating current output ports of the two second full-bridge circuits 3000 are respectively connected with the first input winding 3101 and the second input winding 3102 of the two input-one output high-frequency transformer 3100, the first output winding 3104 of the two input-one output high-frequency transformer 3100 is connected with the alternating current input end of the third full-bridge circuit 3200, the direct current output end of the third full-bridge circuit 3200 is connected with the second capacitor 3300, and the second capacitor 3300 is connected with the energy storage unit 4 through the output ports 301 and 302. The second full-bridge circuit 3000 performs the function of inverting the dc into ac, the two-input one-output high-frequency transformer 3100 performs the functions of electrical isolation and voltage conversion, the third full-bridge circuit 3200 performs the function of rectifying the ac into dc, and the second capacitor 3300 performs the functions of dc voltage support and filtering.
The isolated DC/DC circuit 3 of the fully centralized energy storage system i includes various structures, and in this embodiment, is a second isolated DC/DC circuit, as shown in fig. 8, it is composed of two second full bridge circuits 3000, a two-input one-output high frequency transformer 3100, a third full bridge circuit 3200, a second capacitor 3300, a second half bridge circuit 3400, and a first inductor 3500, that is, on the basis of the first isolated DC/DC circuit, a second half bridge circuit 3400 and a first inductor 3500 are added. The second capacitor 3300 is connected to the input port of the second half-bridge circuit 3400 through a dc output port, and the output port of the second half-bridge circuit 3400 is connected to the first inductor 3500 in series, and then connected to the energy storage unit 4 through the output ports 301 and 302. The second half-bridge circuit 3400 and the first inductor 3500 are connected in series to form a Buck-Boost voltage-boosting circuit, and the first inductor 3500 completes the function of inductive filtering.
The isolated DC/DC circuit 3 of the fully centralized energy storage system i includes various structures, and in this embodiment, is a third isolated DC/DC circuit, and as shown in fig. 9, it is composed of 4 third capacitors 3600, two third half-bridge circuits 3700, a two-input one-output high-frequency transformer 3100, a third full-bridge circuit 3200, and a second capacitor 3300, that is, on the basis of the first isolated DC/DC circuit, two second full-bridge circuits 3000 are replaced with two pairs of third capacitors 3600, which are respectively connected in parallel with the two third half-bridge circuits 3700. The two third capacitors 3600 are connected in series and then connected with the input terminal 13 of the third half-bridge circuit 3700 in parallel to be connected with the upper output terminal P of the energy storage system interface P2, the input terminal 14 is connected with the lower output terminal P 'of the energy storage system interface P2, the input terminal 23 is connected with the upper output terminal N' of the energy storage system interface N2, and the input terminal 24 is connected with the lower output terminal N of the energy storage system interface N2. The ac output ports of the two third half-bridge circuits 3700 are respectively connected to the first input winding 3101 and the second input winding 3102 of the two-input one-output high-frequency transformer 3100, the first output winding 3104 of the two-input one-output high-frequency transformer 3100 is connected to the ac input terminal of the third full-bridge circuit 3200, the dc output terminal of the third full-bridge circuit 3200 is connected to the second capacitor 3300, and the second capacitor 3300 is connected to the energy storage unit 4 through the output ports 301 and 302. After being connected in series, the two third capacitors 3600 and the third half-bridge circuit 3700 are connected in parallel to finish the automatic correction of the magnetic bias of the transformer together, and the direct current is inverted into alternating current.
In this embodiment, as shown in fig. 10, the isolated DC/DC circuit 3 is an isolated DC/DC circuit 3 of a symmetric centralized energy storage system ii, where the isolated DC/DC circuit 3 is composed of two identical vertical symmetric structures 3P and 3N, and the isolated DC/DC circuit 3 includes two input ports and two output ports outside. The isolated DC/DC circuit 3 includes a plurality of structures inside 3P and 3N, which are 3P and 3N structures in the first isolated DC/DC circuit in this embodiment, and the isolated DC/DC circuit 3 is composed of two second full-bridge circuits 3000, two one-input-one-output high-frequency transformers 3800, two fourth full-bridge circuits 3900, and two fourth capacitors 3330 in total. The second full-bridge circuit 3000 includes four first power switching tubes 2001, the one-input-one-output high-frequency transformer 3800 includes a third input winding 3801, a second output winding 3803 and a second magnetic core 3802, the fourth full-bridge circuit 3900 includes four third power switching tubes 3901, and the third power switching tubes 3901 are different from the first power switching tubes 2001 and the second power switching tubes 3201 in device withstand voltage and current parameters. An input terminal 13 in a second full bridge circuit 3000 in a 3P structural circuit in the isolated DC/DC circuit 3 is connected with an upper output terminal P of an energy storage system interface P2, an input terminal 14 is connected with a lower output terminal P 'of an energy storage system interface P2, an input terminal 23 in a 3N structural circuit in the isolated DC/DC circuit 3 is connected with an upper output terminal N' of an energy storage system interface N2, and an input terminal 24 is connected with a lower output terminal N of an energy storage system interface N2. The 3P and 3N in the first isolated DC/DC circuit 3 are two same symmetrical structures, in each structure, the ac output port of the second full-bridge circuit 3000 is connected to the third input winding 3801 of an input-output high-frequency transformer 3800, the second output winding 3803 of the input-output high-frequency transformer 3800 is connected to the ac input terminal of the fourth full-bridge circuit 3900, the DC output terminal of the fourth full-bridge circuit 3900 is connected to the fourth capacitor 3330, the fourth capacitor 3330 in the 3P structure is connected to the input ports 403 and 404 of ESUP in the energy storage unit 4 through the output ports 303 and 304, and the fourth capacitor 3330 in the 3N structure is connected to the input ports 405 and 406 of ESUN in the energy storage unit 4 through the output ports 305 and 306. The second full-bridge circuit 3000 performs the function of inverting the dc into ac, the first input-output high frequency transformer 3800 performs the functions of electrical isolation and voltage conversion, the fourth full-bridge circuit 3900 performs the function of rectifying the ac into dc, and the fourth capacitor 3330 performs the functions of dc voltage support and filtering.
The isolated DC/DC circuit 3 of the symmetric centralized energy storage system ii includes multiple structures, which is a second isolated DC/DC circuit in this embodiment, as shown in fig. 11, the isolated DC/DC circuit 3 is composed of two identical vertical symmetric structures 3P and 3N, and the isolated DC/DC circuit 3 is composed of two second full-bridge circuits 3000, two one-input-one-output high-frequency transformers 3800, two fourth full-bridge circuits 3900, two fourth capacitors 3330, two fourth half-bridge circuits 3331, and two second inductors 3332, that is, two fourth half-bridge circuits 3331 and two second inductors 3332 are added on the basis of the first isolated DC/DC circuit in the energy storage mode. The fourth capacitor 3330 is connected via a dc output port to an input port of the fourth half-bridge 3331, the output port of the fourth half-bridge 3331 is connected in series with the second inductor 3332 to an output port, the 3P configuration is connected via output ports 303, 304 to input ports 403, 404 of ESUP in the energy storage unit 4, and the 3N configuration is connected via output ports 305, 306 to input ports 405, 406 of ESUN in the energy storage unit 4. The fourth half-bridge circuit 3331 and the second inductor 3332 are connected in series to form a Buck-Boost voltage-boosting circuit, and the second inductor 3332 performs an inductive filtering function.
The isolated DC/DC circuit 3 of the symmetric centralized energy storage system ii includes multiple structures, and in this embodiment, is a third isolated DC/DC circuit, as shown in fig. 12, the isolated DC/DC circuit 3 is composed of two identical upper and lower symmetric structures 3P and 3N, and the isolated DC/DC circuit 3 is composed of 4 third capacitors 3600, two third half-bridge circuits 3700, one input-one output high-frequency transformer 3800, two fourth full-bridge circuits 3900, and two fourth capacitors 3330 in total, that is, on the basis of the first isolated DC/DC circuit in this model, the two second full-bridge circuits 3000 are replaced by two pairs of third capacitors 3600, and then are connected in parallel to the two third half-bridge circuits 3700, respectively. The two third capacitors 3600 are connected in series and then connected with the input terminal 13 of the third half-bridge circuit 3700 in parallel to be connected with the upper output terminal P of the energy storage system interface P2, the input terminal 14 is connected with the lower output terminal P 'of the energy storage system interface P2, the input terminal 23 is connected with the upper output terminal N' of the energy storage system interface N2, and the input terminal 24 is connected with the lower output terminal N of the energy storage system interface N2. In the third isolated DC/DC circuit 3, two symmetric structures, 3P and 3N, are the same, in each structure, the ac output port of the third half-bridge circuit 3700 is connected to the third input winding 3801 of the input-output high-frequency transformer 3800, the second output winding 3803 of the input-output high-frequency transformer 3800 is connected to the ac input terminal of the fourth full-bridge circuit 3900, the DC output terminal of the fourth full-bridge circuit 3900 is connected to the fourth capacitor 3330, the fourth capacitor 3330 in the 3P structure is connected to the input ports 403 and 404 of ESUP in the energy storage unit 4 through the output ports 303 and 304, and the fourth capacitor 3330 in the 3N structure is connected to the input ports 405 and 406 of ESUN in the energy storage unit 4 through the output ports 305 and 306. After being connected in series, the two third capacitors 3600 and the third half-bridge circuit 3700 are connected in parallel to finish the automatic correction of the magnetic bias of the transformer together, and the direct current is inverted into alternating current.
In this embodiment, as shown in fig. 13, the energy storage unit 4 is formed by connecting a plurality of battery energy storage units 4001 in series, and the charging and discharging functions are achieved through reasonable control in the above embodiments. The number, volume and capacity of the battery energy storage monomers can be changed according to the system capacity. The type of the energy storage monomer is not limited to this, and other suitable energy storage monomers can be accessed.
In this embodiment, as shown in fig. 14, the energy storage unit 4 is formed by connecting a plurality of super capacitor energy storage monomers 4002 in series, and the charging and discharging functions are achieved through reasonable control in the above embodiments. The number, the volume and the capacity of the super capacitor energy storage monomers can be changed according to the system capacity. The type of the energy storage monomer is not limited to this, and other suitable energy storage monomers can be accessed.
The above embodiments are merely illustrative, and do not limit the scope of the invention, and the invention may be modified in various kinds, structures, dimensions, positions and capacities of the components, and on the basis of the technical solution of the invention, the modifications and equivalents of the individual components according to the description and drawings of the invention or the direct and indirect application thereof to other related fields shall be covered by the scope of the invention.
Those not described in detail in this specification are within the skill of the art.

Claims (9)

1. A symmetrical energy storage system based on a modular multilevel converter, comprising: the system comprises a modular multilevel converter (1), an energy storage system interface p2, an energy storage system interface n2, an isolated DC/DC circuit (3), an energy storage unit (4), a positive high-voltage direct-current bus, a self-guiding positive high-voltage direct-current bus, a negative high-voltage direct-current bus and a self-guiding negative high-voltage direct-current bus;
the modular multilevel converter (1) is composed of k-phase 2k bridge arms; each phase of bridge arm comprises an upper bridge arm and a lower bridge arm; each phase of upper bridge arm is composed of upper bridge arm inductor LpiAnd submodules 2 to n are connected in series, and each phase of lower bridge arm is composed of a lower bridge arm inductor LniAnd submodules n +1 to 2n-1 are connected in series;
the energy storage system interface p2 includes: energy storage system submodule SMPiEnergy storage System submodule SMPiAre connected in parallel; the energy storage system submodule is SMPiThe method comprises the following steps: upper power tube Tp2i-1And lower power tube Tp2iUpper power tube Tp2i-1And lower power tube Tp2iAre connected in series;
the energy storage system interface n2 includes: energy storage system submodule SMNiEnergy storage system submodule SMNiAre connected in parallel; the energy storage system submodule SMNiThe method comprises the following steps: upper power tube Tn2i-1And a lower power tube Tn2iUpper power tube Tn2i-1And a lower power tube Tn2iAre connected in series;
the energy storage system submodule is SMPiThrough an upper power tube Tp2i-1Connected with a positive high-voltage direct-current bus, and an energy storage system submodule SMPiThrough the lower power tube Tp2iIs connected with a self-guiding positive high-voltage direct current bus; the energy storage system submodule SMNiThrough an upper power tube Tn2i-1Connected with a self-induced negative high-voltage direct-current bus, and an energy storage system submodule SMNiThrough a lower power tube Tn2iIs connected with a negative high-voltage direct-current bus;
the k-phase input end of the modular multilevel converter (1) is connected with k-phase high-voltage alternating current, and the output end of each phase is connected with the energy storage system submodule SMPiThe input ends of the sub-modules are connected, and the lower output end of each phase is connected with the SMN sub-module of the energy storage systemiThe input ends of the two-way valve are connected;
the output end of the energy storage system interface p2 and the output end of the energy storage system interface n2 are respectively connected with the input end of an isolated DC/DC circuit (3), the output end of the isolated DC/DC circuit (3) is connected with an energy storage unit (4), wherein i is 1,2, · · k;
the modular multilevel converter (1) is characterized in that a half-bridge submodule is adopted as a submodule and adopts two different access modes, the half-bridge submodule internally comprises two power switch tubes and a capacitor, the half-bridge submodule in each phase of upper bridge arm is connected in series through a certain number, and one end of the half-bridge submodule is connected with an energy storage System (SMP) submoduleiIs connected with the input end of the upper bridge arm inductor L, and the other end of the upper bridge arm inductor L is connected with the input end of the lower bridge arm inductor LpiConnecting; the half-bridge submodules in each phase of lower bridge arm are connected in series in a certain number, and one end of each half-bridge submodule is connected with the storageSystem-capable submodule SMNiIs connected with the input end of the lower bridge arm inductor L, and the other end of the lower bridge arm inductor L is connected with the input end of the lower bridge arm inductor LniConnecting; according to the actual working condition, comprehensively considering the system cost and whether the fault ride-through capability exists, correspondingly selecting a full-bridge submodule, a clamping type submodule and a reverse resistance type half-bridge submodule;
the energy storage system submodule is SMPiThe input end of the energy storage system interface P2 is connected with the output end of the submodule 2 of each phase upper bridge arm, the upper output end P and the lower output end P 'of the energy storage system interface P2 are respectively connected with the input end P and the input end P' of the isolated DC/DC circuit (3), and the energy storage system submodule SMN is connected with the output end of the submodule 2 of each phase upper bridge armiThe input end of the energy storage system interface N2 is connected with the output end of the submodule 2N-1 of each phase of lower bridge arm, and the lower output end N and the upper output end N 'of the energy storage system interface N2 are respectively connected with the input end N and the input end N' of the isolated DC/DC circuit (3), wherein i is 1,2, · · k;
the level number, the structures of the upper bridge arm submodule and the lower bridge arm submodule of each phase and the input alternating voltage phase number of the modular multilevel converter (1) are correspondingly adjusted according to the system capacity grade, the system fault redundancy working mode and the voltage-resistant grade of a power switch tube in the upper bridge arm submodule and the lower bridge arm submodule of each phase;
the energy storage unit (4) is formed by connecting a plurality of energy storage batteries or super capacitors or other energy storage sub-units in series.
2. The modular multilevel converter based symmetric energy storage system according to claim 1, wherein the isolated DC/DC circuit (3) comprises two input ports and one output port on the outside, and the isolated DC/DC circuit (3) comprises 2 inverter sub-modules, 1 two-input one-output high frequency transformer and 1 rectifier sub-module on the inside; the inverter submodule adopts an H-bridge inverter circuit or a half-bridge inverter circuit, and the rectifier submodule adopts an H-bridge rectifier circuit or a Buck-Boost voltage-boosting circuit behind the H-bridge rectifier circuit; the input end P and the input end P 'of the isolation type DC/DC circuit (3) are respectively connected with the upper output end P and the lower output end P' of the energy storage system interface P2, the input end N and the input end N 'of the isolation type DC/DC circuit (3) are respectively connected with the lower output end N and the upper output end N' of the energy storage system interface N2, and the output end of the isolation type DC/DC circuit (3) is connected with the input end of the energy storage unit (4) so as to form a fully centralized energy storage system I.
3. The symmetrical energy storage system based on the modular multilevel converter according to claim 2, wherein the 2 inverter sub-modules in the fully centralized energy storage system i all adopt H-bridge inverter circuits, wherein an input end of one H-bridge inverter circuit is connected to an output end of the energy storage system interface p2 through a parallel flying capacitor, an input end of the other H-bridge inverter circuit is connected to an output end of the energy storage system interface n2 through a parallel flying capacitor, output ends of the 2H-bridge inverter circuits are respectively connected to two input ends of a two-input one-output high frequency transformer, and output ends of the two-input one-output high frequency transformer are connected to an H-bridge rectifier circuit.
4. The symmetrical energy storage system based on the modular multilevel converter according to claim 2, wherein the 2 inverter sub-modules in the fully centralized energy storage system i all adopt H-bridge inverter circuits, wherein an input end of one H-bridge inverter circuit is connected with an output end of the energy storage system interface p2 through a parallel flying capacitor, an input end of the other H-bridge inverter circuit is connected with an output end of the energy storage system interface n2 through a parallel flying capacitor, output ends of the 2H-bridge inverter circuits are respectively connected with two input ends of a two-input one-output high-frequency transformer, and an output end of the two-input one-output high-frequency transformer is connected with the H-bridge rectifier circuit and then connected with the Buck-Boost voltage-reduction circuit.
5. The symmetrical energy storage system based on modular multilevel converter according to claim 2, wherein the 2 inverter sub-modules in the fully centralized energy storage system i are half-bridge inverter circuits, wherein the input end of one half-bridge inverter circuit is connected in parallel with two serially connected capacitors and then connected with the output end of the energy storage system interface p2, the input end of the other half-bridge inverter circuit is connected in parallel with two serially connected capacitors and then connected with the output end of the energy storage system interface n2, the output ends of 2 half-bridge inverter circuits are respectively connected with the two input ends of the two-input one-output high frequency transformer, and the output ends of the two-input one-output high frequency transformer are connected with the H-bridge rectifier circuit.
6. The modular multilevel converter based symmetric energy storage system according to claim 1, wherein the isolated DC/DC circuit (3) comprises two input ports and two output ports on the outside, and the isolated DC/DC circuit (3) comprises 2 inverter sub-modules, 2 one input one output high frequency transformers and 2 rectifier sub-modules on the inside; the outside of the energy storage unit (4) comprises two input ports; the inverter submodule adopts an H-bridge inverter circuit or a half-bridge inverter circuit, and the rectifier submodule adopts an H-bridge rectifier circuit or a Buck-Boost voltage-boosting circuit after H-bridge rectification; an input end P and an input end P 'of the isolation type DC/DC circuit (3) are respectively connected with an upper output end P and a lower output end P' of the energy storage system interface P2, an input end N and an input end N 'of the isolation type DC/DC circuit (3) are respectively connected with a lower output end N and an upper output end N' of the energy storage system interface N2, and two output ends of the isolation type DC/DC circuit (3) are respectively connected with two input ends of the energy storage unit (4) to form a symmetrical centralized energy storage system II.
7. The symmetrical energy storage system based on the modular multilevel converter according to claim 6, wherein the 2 inverter sub-modules in the symmetrical centralized energy storage system II are all H-bridge inverter circuits, wherein an input terminal of one H-bridge inverter circuit is connected to an output terminal of the energy storage system interface p2 through a parallel flying capacitor, an input terminal of the other H-bridge inverter circuit is connected to an output terminal of the energy storage system interface n2 through a parallel flying capacitor, an output terminal of the H-bridge inverter circuit is connected to an input terminal of an input-output high frequency transformer, and an output terminal of the input-output high frequency transformer is connected to an H-bridge rectification circuit.
8. The symmetrical energy storage system based on the modular multilevel converter according to claim 6, wherein the 2 inverter sub-modules in the symmetrical centralized energy storage system II are all H-bridge inverter circuits, wherein an input end of one H-bridge inverter circuit is connected with an output end of the energy storage system interface p2 through a parallel flying capacitor, an input end of the other H-bridge inverter circuit is connected with an output end of the energy storage system interface n2 through a parallel flying capacitor, an output end of the H-bridge inverter circuit is connected with an input end of an input-output high-frequency transformer, and an output end of the input-output high-frequency transformer is connected with the H-bridge rectifier circuit and then connected with the Buck-Boost voltage-boosting circuit.
9. The symmetrical energy storage system based on modular multilevel converter according to claim 6, wherein the 2 inverter sub-modules in the symmetrical centralized energy storage system II are half-bridge inverter circuits, wherein the input end of one half-bridge inverter circuit is connected in parallel with two series capacitors and then connected with the output end of the energy storage system interface p2, the input end of the other half-bridge inverter circuit is connected in parallel with two series capacitors and then connected with the output end of the energy storage system interface n2, the output end of the half-bridge inverter circuit is connected with the input end of an input-output high frequency transformer, and the output end of the input-output high frequency transformer is connected with the H-bridge rectifier circuit.
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Application publication date: 20180720

Assignee: Huayi Changneng (Beijing) Technology Co.,Ltd.

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Denomination of invention: A Symmetric Energy Storage System Based on Modular Multilevel Converters

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Record date: 20230919