CN116207765A - Primary power conversion topology of flow battery energy storage system - Google Patents

Primary power conversion topology of flow battery energy storage system Download PDF

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Publication number
CN116207765A
CN116207765A CN202310297334.9A CN202310297334A CN116207765A CN 116207765 A CN116207765 A CN 116207765A CN 202310297334 A CN202310297334 A CN 202310297334A CN 116207765 A CN116207765 A CN 116207765A
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energy storage
pile
liquid
topology
electric
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颜湘武
蔡光
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North China Electric Power University
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North China Electric Power University
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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
    • H02J3/28—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
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • 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
    • 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
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Fuel Cell (AREA)

Abstract

The invention discloses a primary power conversion topology of a flow battery energy storage system, which comprises a pile series group topology of a cross pile group and a primary energy storage converter topology. The pile group topology is formed by connecting a pile of a plurality of pile groups in series, the primary energy storage converter topology is formed by a voltage source type PWM converter (VSC), the direct current side of the primary energy storage converter topology is connected with the pile in series, and the alternating current side of the primary energy storage converter topology is connected with an alternating current power grid through an isolation transformer. The invention avoids the series connection of the electric piles in the same electric pile group so as to avoid leakage current loss and improve the voltage of the series connection of the electric piles in groups, and on the basis, the high-efficiency high-power grid connection of the energy storage system can be realized only through one-stage DC/AC bidirectional conversion. The invention has the advantages of reducing leakage current loss, increasing the series number of the galvanic piles, improving the voltage of the direct current bus, reducing the power conversion links, and improving the power level and the efficiency of the energy storage system of the flow battery in three dimensions.

Description

Primary power conversion topology of flow battery energy storage system
Technical Field
The invention belongs to the technical field of energy storage systems for flow batteries, and particularly relates to a power conversion topology of an energy storage system for a flow battery.
Background
The energy storage technology is a key support technology for constructing a novel power system taking new energy as a main body, wherein the flow battery energy storage technology has the advantages of safety, reliability, environmental protection, long service life and the like, and is one of the first choice for constructing long-time and large-scale energy storage.
Large-scale flow battery energy storage systems are typically integrated from multiple groups of stack modules. The electric pile is generally formed by connecting a plurality of single cells in series, and uniformly supplying electrolyte through a storage tank and a liquid path system, wherein the electrolyte is distributed to the single cells in parallel through a common pipeline.
In engineering application, in order to meet actual demands, a plurality of electric piles are required to be connected in series and parallel, high-voltage and high-power output is achieved, when the electric pile groups of the same pair of electrolyte storage tanks are connected in series and parallel to operate in groups, a liquid path system between the electric piles can generate leakage current, the leakage current distribution inside the electric piles and the voltage distribution of single cells inside the electric piles are affected, and under the influence of new leakage current, after the electric piles in the same liquid path system are connected in series, the voltage level of the single electric pile is lower than that of the single electric pile before the series connection.
Conventional energy storage converters are generally classified into one-stage energy storage converters and two-stage energy storage converters. The primary energy storage converter has the advantages of simple circuit, small loss, and electric energy only needs to be subjected to one-time DC/AC conversion, and has the defect of insufficient boosting and reducing voltage capability, and a direct current side of an energy storage system is required to directly provide a higher voltage level. The two-stage energy storage converter is characterized in that a DC/DC converter is added between an energy storage battery and the DC/AC converter on the basis of one stage to boost (discharge) and buck (charge), and the two-stage energy storage converter is a grid-connected conversion mode adopted by most of traditional flow battery energy storage systems, and has the defects that the two-stage conversion increases the complexity and the control difficulty of the structure of the energy storage system, and reduces the efficiency and the reliability of the energy storage system.
Disclosure of Invention
The invention provides a primary power conversion topology of a flow battery energy storage system, which does not adopt a method of series connection of electric piles in the same electric pile group (liquid path system), but connects electric piles at any position respectively provided in different electric pile groups (liquid path system) in series to improve the voltage level of the series connection of the electric piles, thereby simplifying the topology structure of the energy storage converter, and improving the power capacity, the efficiency and the reliability of the flow battery energy storage system by adopting primary DC/AC power conversion.
The primary power conversion topology of the flow battery energy storage system is characterized by mainly comprising a pile series group topology of a cross pile group and a primary energy storage converter topology cascade connection.
The flow battery energy storage system is composed of a plurality of sets of liquid path systems, in one set of liquid path system, a pair of positive and negative electrolyte storage tanks are connected with a positive and negative electrolyte inlet and outlet of a galvanic pile through positive and negative electrolyte path pipelines, and form an electrolyte circulation loop with the liquid path pipelines in the galvanic pile, and electrolyte is provided for a plurality of galvanic piles under the driving of a liquid pump.
The positive and negative electrolyte liquid path pipeline comprises:
an anode liquid path liquid inlet bypass pipe: the positive electrode electrolyte inlet of the galvanic pile is connected with the positive electrode liquid path liquid inlet public pipeline;
positive electrode liquid outlet side pipe: the positive electrode electrolyte outlet of the galvanic pile is connected with the positive electrode liquid outlet public pipeline (10);
positive pole liquid way feed liquor public pipeline: the liquid pump is arranged at the position close to the outlet of the storage tank and is connected between the positive electrolyte inlet bypass pipe and the outlet of the positive electrolyte storage tank;
positive electrode liquid outlet public pipeline: the positive electrode electrolyte outlet side pipe is connected between the positive electrode electrolyte outlet side pipe and the inlet of the positive electrode electrolyte storage tank;
negative electrode liquid path liquid inlet bypass pipe: the negative electrode electrolyte inlet of the galvanic pile is connected with the negative electrode liquid path liquid inlet public pipeline;
negative electrode liquid outlet side pipe: the negative electrode electrolyte outlet of the galvanic pile is connected with the negative electrode liquid outlet public pipeline;
negative electrode liquid path liquid inlet public pipeline: the negative electrode electrolyte liquid inlet bypass pipe is connected with the outlet of the negative electrode electrolyte storage tank, and a liquid pump is arranged at the position close to the outlet of the storage tank;
negative pole liquid way goes out liquid public pipeline: and the negative electrode electrolyte outlet side pipe is connected between the negative electrode electrolyte outlet side pipe and the inlet of the negative electrode electrolyte storage tank.
A plurality of stacks, which are supplied with liquid from a set of liquid circuit systems, are called a stack group.
Before explaining the topology of the electrical connection between stacks in the present invention, it is necessary to explain the definition of the series connection of stacks in the present invention:
when two electric stacks exist, the cathode of the first electric stack is connected with the anode of the second electric stack through an electric connecting wire, the anode of the first electric stack is used as the total anode after connection, and the cathode of the second electric stack is used as the total cathode after connection;
when a plurality of electric stacks exist, the former electric stack and the latter electric stack are connected in series according to the two electric stacks, the positive electrode of the first electric stack is used as the total positive electrode after connection, and the negative electrode of the last electric stack is used as the total negative electrode after connection;
a plurality of stacks having the above-described series connection relationship constitute a stack string.
The series grouping mode adopted by the series grouping topology of the electric piles of the cross-electric pile group is that a plurality of electric pile groups (liquid circuit systems) respectively provide electric piles with the same position or different positions for series connection to form an electric pile string of the cross-electric pile group, and the electric piles with the series connection mode connection relation form an electric pile series grouping topology structure of the cross-electric pile group.
For example: and the flow battery energy storage is provided with n sets of liquid path systems and n corresponding electric pile groups, and each electric pile group is provided with m electric piles, so that according to the series grouping mode, the electric piles of the cross electric pile groups are connected in series to form an electric pile string.
The pile series connection grouping topology of the cross pile group avoids electric connection among piles in the pile group of the same liquid path system, so that no potential difference exists in the side pipe and the public pipe of the same pile group liquid path system, leakage current loss generated by electrolyte in the liquid path pipeline among piles is eliminated, consistency of pile voltages in pile strings is improved, and series connection quantity of piles and integral voltage of pile strings are conveniently improved.
Because the voltage level of the pile string is improved, the energy storage converter topology does not need a DC/DC conversion link, and the current conversion requirement of the liquid flow energy storage system can be met only by connecting the primary DC/AC converter with an alternating current power grid through an isolation transformer, so that the primary energy storage converter topology is formed.
The primary energy storage converter topology comprises a primary DC/AC converter, a direct current bus capacitor, an LCL filter and an isolation transformer;
the primary DC/AC converter adopts a two, three and multi-level equal-voltage source type PWM converter (VSC), the DC side of the converter is connected in parallel with a DC bus capacitor to form the topological DC side of the primary energy storage converter, and the AC side of the converter is connected in series with an LCL filter and an isolation transformer to form the topological AC side of the primary energy storage converter;
and finally, the topological direct current side of the primary energy storage converter is connected with the total positive electrode and the total negative electrode of the pile string formed by the pile series connection group topology of the cross pile group, and the topological alternating current side of the primary energy storage converter is connected with an alternating current power grid to form the primary power conversion topology of the flow battery energy storage system.
The method provided by the invention has the following beneficial effects:
the primary power conversion topology of the flow battery energy storage system can avoid electric connection between electric piles in the same electric pile group (liquid path system), eliminates potential difference on liquid path pipelines, and solves the problem of leakage current loss of the liquid path system outside the electric pile;
the consistency of the pile voltage in the pile string is improved;
the series quantity and the series voltage level of the electric pile are improved, the high-voltage integration of the electric pile string can be realized, and the overall voltage and the power level of the electric pile string are improved;
the DC bus voltage of the energy storage converter is improved, the DC/DC boosting (discharging) and dropping (charging) links of the energy storage converter are omitted, and the power conversion links are reduced;
the primary power conversion topology of the flow battery energy storage system formed by cascading the primary energy storage converter topology and the cell pile series group topology of the cross cell pile group improves the capacity, efficiency and reliability of the power conversion of the energy storage system.
Drawings
Fig. 1 is a schematic diagram of primary power conversion topology of a flow battery energy storage system provided in the present application;
fig. 2 is a schematic diagram of a connection relationship of a liquid path system of a topology structure provided in the present application.
Detailed Description
The following provides a further detailed description of the proposed solution of the invention with reference to the accompanying drawings and detailed description. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in a very simplified form and are all to a non-precise scale, merely for the purpose of facilitating and clearly aiding in the description of embodiments of the invention. For a better understanding of the invention with objects, features and advantages, refer to the drawings. It should be understood that the structures, proportions, sizes, etc. shown in the drawings are for illustration purposes only and should not be construed as limiting the invention to the extent that any modifications, changes in the proportions, or adjustments of the sizes of structures, proportions, or otherwise, used in the practice of the invention, are included in the spirit and scope of the invention which is otherwise, without departing from the spirit or essential characteristics thereof.
In a conventional flow battery energy storage system, a two-stage energy storage converter topology structure of a front-stage DC/DC converter is needed because the series voltage of a battery is not high enough, and the front-stage DC/DC converter realizes the conversion of boosting (discharging) and reducing (charging), so that the voltage of a direct current bus meets the grid-connected requirement of a rear-stage converter, and then grid-connected operation is realized through the rear-stage DC/AC converter. Although the two-stage energy storage converter is introduced with the DC/DC converter, the voltage and capacity configuration of the flow battery is more flexible, the cost and the control complexity of the energy storage converter are increased due to the addition of the DC/DC converter, and the power conversion efficiency of the two-stage energy storage converter is lower than that of the one-stage energy storage converter. In order to enable the direct-current voltage of the flow battery energy storage system to be high enough, the requirements of high power capacity and high efficiency of the flow battery energy storage system are met, the number of series-connected electric piles needs to be increased, but under the same flow system, the larger the number of the electric piles connected in series, the more obvious the leakage current loss is among the electric piles, the more serious the voltage inconsistency of the series-connected electric piles is, the effect of 1+1<2 is caused, the level of the series-connected voltage of the whole electric pile is directly influenced, and the flow battery energy storage system is also a main challenge facing high-capacity integration of the flow battery energy storage system. Therefore, the invention provides a primary power conversion topology of the flow battery energy storage system.
As shown in fig. 1, an embodiment of the present invention provides a primary power conversion topology of a flow battery energy storage system, the conversion topology being formed by a series stack group topology across a stack group and a primary energy storage converter topology cascade.
The pile series-connection grouping topology comprises n sets of liquid path systems, n is m piles 100, each set of liquid path system provides electrolyte for m piles 100 to form a pile group 500, and n pile groups 500 are arranged in the whole topology and correspond to the n sets of liquid path systems.
Specifically, the liquid path system consists of a positive and negative electrolyte storage tank, a positive and negative electrolyte liquid path pipeline, a liquid path pipeline in the galvanic pile and a liquid pump,
the pair of positive and negative electrolyte storage tanks are connected with positive and negative electrolyte inlets and outlets of the m stacks through a set of positive and negative electrolyte liquid path pipelines to form a liquid path circulation loop, and a set of liquid path system is formed under the driving of the two liquid pumps.
Specifically, as shown in fig. 2, the connection relationship between the positive and negative electrolyte liquid path pipes is as follows:
the positive electrode liquid inlet bypass pipe 300 is connected between the positive electrode electrolyte inlet 101 of the electric pile and the positive electrode liquid inlet common pipe 304;
the anode liquid outlet side pipe 301 is connected between the anode electrolyte outlet 102 of the electric pile and the anode liquid outlet common pipe 305;
the positive electrode liquid path liquid inlet public pipeline 304 is connected between the positive electrode electrolyte liquid inlet bypass pipe 300 and the outlet 203 of the positive electrode electrolyte storage tank, and a liquid pump 400 is arranged near the outlet of the storage tank;
the positive electrode liquid outlet public pipeline 305 is connected between the positive electrode electrolyte liquid outlet side pipe 301 and the inlet 202 of the positive electrode electrolyte storage tank;
a negative electrode liquid path liquid inlet bypass pipe 302 is connected between a negative electrode electrolyte inlet 103 of the electric pile and the negative electrode liquid path liquid inlet common pipeline 306;
the negative electrode liquid outlet side pipe 303 is connected between the negative electrode electrolyte outlet 104 of the electric pile and the negative electrode liquid outlet public pipe 307;
the negative electrode liquid path liquid inlet public pipeline 306 is connected between the negative electrode electrolyte liquid inlet bypass pipe 302 and the outlet 205 of the negative electrode electrolyte storage tank, and a liquid pump 400 is arranged near the outlet of the storage tank;
a negative electrolyte outlet common pipe 307 is connected between the negative electrolyte outlet bypass pipe 303 and the inlet 204 of the negative electrolyte tank.
The liquid path system structure under the topology provided by the invention is the above. In this embodiment, a set of fluid circuit systems may provide electrolyte to m stacks 100, which m stacks 100 are referred to as a stack assembly 500 in this embodiment.
Further, the electrical connection manner between the stacks 100 in this embodiment is described:
in general, in order to increase the voltage level of the flow battery energy storage system, a plurality of stacks 100 are required to be connected in series, and conventionally, the stacks 100 are connected in series under the same stack group (liquid path system), so that a voltage difference of a liquid path pipeline is generated, leakage current loss is caused, and the stack voltage is reduced, and therefore, the invention proposes a stack series connection mode of a cross-stack group.
First, the series connection in the present embodiment means:
when two stacks exist, the cathode 106 of the first stack is connected with the anode 105 of the second stack through an electrical connecting wire, the anode 105 of the first stack is used as a total anode 700 after connection, and the cathode 106 of the second stack is used as a total cathode 701 after connection;
when there are a plurality of stacks 100, the previous stack 100 and the next stack 100 are connected in series, the positive electrode 105 of the first stack is used as the total positive electrode 700 after connection, and the negative electrode 106 of the last stack is used as the total negative electrode 701 after connection;
in the present embodiment, the plurality of stacks 100 having the above-described series connection relationship are referred to as a group of stack strings 600.
Specifically, in the stack string of the cross-stack group in this embodiment, as shown in fig. 1, each stack group 500 provides a stack 100 with the same position for sorting, and then connects the cathode 106 of the previous stack 100 with the anode 105 of the next stack 100, where the anode 105 of the stack 100 at the head end of the stack string is the total anode 700 of the stack string, and the cathode 106 of the stack at the tail end of the stack string is the total cathode 701 of the stack string. In addition to this embodiment, the stack strings across the stack groups may also select stacks 100 that are located differently in each stack group for series connection.
In the conventional flow battery energy storage system pile series group topology, pile strings are generally formed by pile series connection in the same liquid path system, and leakage current exists in liquid path pipelines connected between the piles due to potential difference between the piles. In addition, the stacks in the stack string in the embodiment have electrical connection and potential difference, but have no connection relation on a liquid path, so that leakage current cannot be generated in the stack string.
In this embodiment, the number of the series-connected electric piles 100 in the electric pile string 600 is determined by the number of the electric pile groups 500, so that the series-connected voltage of the electric pile string 600 is more flexible to adjust, the number of the electric pile series connections can be conveniently increased, and the DC output voltage level of the electric pile string is improved, thereby, the current-converting requirement of the liquid flow energy storage system can be met only by primary DC/AC power conversion, and the DC/DC current-converting link in the original secondary energy storage converter topology is omitted.
As shown in fig. 1, a primary DC/AC converter, a direct current bus capacitor, an LCL filter, and an isolation transformer form the primary energy storage converter topology;
the direct current side 801 of the primary DC/AC converter 800 is connected in parallel with a direct current bus capacitor 805 to form a topological direct current side 806 of the primary energy storage converter;
the AC side 802 of the primary DC/AC converter 800 is connected in series with an LCL filter 803 and an isolation transformer 804 to form a primary energy storage converter topology AC side 807;
in this embodiment, the topological direct current side 806 of the primary energy storage converter is connected with the total positive pole 700 and the total negative pole 701 of the pile string, the topological alternating current side 807 of the primary energy storage converter is connected with the alternating current power grid 900, and is connected with the pile series group topology cascade of the cross pile group to form the primary power conversion topology of the flow battery energy storage system.
In addition, the primary DC/AC converter used in the primary energy storage converter topology of the present embodiment includes, but is not limited to, two, three, and multi-level, etc., voltage source type PWM converters (VSCs).
The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (9)

1. The primary power conversion topology of the flow battery energy storage system is characterized by comprising a pile series group topology of a cross pile group and a primary energy storage converter topology;
the pile series connection grouping topology of the pile-crossing groups is formed by respectively providing a pile-crossing pile group by pile groups in a plurality of liquid path systems, wherein the flow battery energy storage system comprises n liquid path systems, and each liquid path system comprises m piles to form a pile group; n liquid path systems form n electric pile groups; each of the n pile groups (liquid path system) provides a pile series connection with the same or different positions to form a group structure (pile series) formed by the n pile series connection;
the topology of the primary energy storage converter consists of a voltage source type PWM converter (VSC), the positive and negative poles of the direct current side are respectively connected with the total positive pole and the total negative pole of the series stack group topology (stack string) of the cross-stack group, and the alternating current side of the topology of the primary energy storage converter is connected with an alternating current power grid through an isolation transformer;
and the pile series group topology of the cross pile group and the primary energy storage converter topology are cascaded to form the primary power conversion topology of the flow battery energy storage system.
2. The primary power conversion topology of a flow battery energy storage system according to claim 1, wherein the liquid routing system is composed of a positive and negative electrolyte storage tank, a positive and negative electrolyte liquid routing pipeline, a liquid routing pipeline in a galvanic pile and a liquid pump, the pair of positive and negative electrolyte storage tanks are connected with a positive and negative electrolyte inlet and outlet of the galvanic pile through the positive and negative electrolyte liquid routing pipeline, and an electrolyte circulation loop is formed with the liquid routing pipeline in the galvanic pile, and a set of liquid routing system is formed under the driving of the liquid pump.
3. The flow battery energy storage system primary power conversion topology of claim 2, wherein the positive and negative electrolyte circuit conduits comprise:
the positive electrode liquid path liquid inlet bypass pipe is connected between a positive electrode electrolyte inlet of the electric pile and the positive electrode liquid path liquid inlet public pipeline;
the positive electrode liquid path liquid outlet side pipe is connected between a positive electrode electrolyte outlet of the electric pile and the positive electrode liquid path liquid outlet public pipeline;
the positive electrode liquid path liquid inlet public pipeline is connected between the positive electrode electrolyte liquid inlet bypass pipe and the outlet of the positive electrode electrolyte storage tank, and a liquid pump is arranged at the position close to the outlet of the storage tank;
the positive electrode liquid outlet public pipeline is connected between the positive electrode electrolyte liquid outlet side pipe and the inlet of the positive electrode electrolyte storage tank;
the negative electrode liquid path liquid inlet bypass pipe is connected between a negative electrode electrolyte inlet of the electric pile and the negative electrode liquid path liquid inlet public pipeline;
the negative electrode liquid path liquid outlet side pipe is connected between a negative electrode electrolyte outlet of the electric pile and the negative electrode liquid path liquid outlet public pipeline;
the negative electrode liquid path liquid inlet public pipeline is connected between the negative electrode electrolyte liquid inlet bypass pipe and the outlet of the negative electrode electrolyte storage tank, and a liquid pump is arranged at the position close to the outlet of the storage tank;
and the negative electrode liquid outlet public pipeline is connected between the negative electrode electrolyte liquid outlet side pipe and the inlet of the negative electrode electrolyte liquid storage tank.
4. The flow battery energy storage system primary power conversion topology of claim 2, wherein said set of fluid path systems provides electrolyte to a plurality of stacks, the stacks comprising a stack group.
5. The flow battery energy storage system primary power conversion topology of claim 4, wherein the stack groups each provide a stack of identical or different locations for electrical series connection, forming a stack string across the stack groups.
6. The flow battery energy storage system primary power conversion topology of claim 5, wherein said series connection comprises:
when two electric stacks exist, the cathode of the first electric stack is connected with the anode of the second electric stack through an electric connecting wire, the anode of the first electric stack is used as the total anode after connection, and the cathode of the second electric stack is used as the total cathode after connection;
when a plurality of electric stacks exist, the former electric stack and the latter electric stack are connected in series according to the two electric stacks, the positive electrode of the first electric stack is used as the total positive electrode after connection, and the negative electrode of the last electric stack is used as the total negative electrode after connection;
a plurality of stacks having the above-described series relationship constitute a stack string.
7. The flow battery energy storage system primary power conversion topology of claim 1, wherein the primary energy storage converter topology comprises a primary DC/AC converter, a direct current bus capacitor, an LCL filter, and an isolation transformer, the primary DC/AC converter employing two, three, and multiple level equal voltage source PWM converters (VSCs).
8. The primary power conversion flow battery energy storage system topology of claim 1, wherein the primary energy storage converter topology DC side is comprised of the primary DC/AC converter DC side parallel DC bus capacitor.
9. The flow battery energy storage system primary power conversion topology of claim 1, wherein the primary energy storage converter topology AC side is comprised of the primary DC/AC converter AC side in series with an LCL filter and isolation transformer.
CN202310297334.9A 2022-11-02 2023-03-24 Primary power conversion topology of flow battery energy storage system Pending CN116207765A (en)

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CN2022113676712 2022-11-02

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