CN117096922A - Distributed energy storage converter and energy storage system - Google Patents
Distributed energy storage converter and energy storage system Download PDFInfo
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- CN117096922A CN117096922A CN202311361797.3A CN202311361797A CN117096922A CN 117096922 A CN117096922 A CN 117096922A CN 202311361797 A CN202311361797 A CN 202311361797A CN 117096922 A CN117096922 A CN 117096922A
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- 238000004146 energy storage Methods 0.000 title claims abstract description 126
- 230000002457 bidirectional effect Effects 0.000 claims description 17
- 238000010586 diagram Methods 0.000 description 13
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 230000004044 response Effects 0.000 description 4
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 238000011217 control strategy Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000009499 grossing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
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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
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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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
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
- H02J7/0014—Circuits for equalisation of charge between batteries
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0067—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
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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
- H02J2207/00—Indexing scheme relating to details of circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J2207/20—Charging or discharging characterised by the power electronics converter
Abstract
The application is applicable to the technical field of energy storage, and provides a distributed energy storage converter and an energy storage system, wherein the distributed energy storage converter comprises at least two power grid parallel connection access modules; each power grid parallel access module comprises at least one converter; each power grid parallel access module comprises a different number of converters; the different power grid parallel connection access modules are used for accessing the battery packs with different characteristic parameters into the power grid; the battery pack consists of a plurality of retired batteries, and the characteristic parameters comprise voltage parameters and capacity parameters; based on a plurality of converters, load distribution and consistency management are carried out on different battery packs, different power grid parallel connection access modules can be formed according to different characteristic parameters of the battery packs formed by retired batteries, so that the problem that the difficulty in consistency management of the battery packs is high due to different specifications of the retired batteries and various types of batteries is solved, and the consistency management of the battery packs in an energy storage system is realized.
Description
Technical Field
The application belongs to the technical field of energy storage, and particularly relates to a distributed energy storage converter and an energy storage system.
Background
Energy storage refers to the process of storing energy through a medium or device and releasing it when needed. With the continuous progress of new energy science and technology, new energy automobiles are increasingly applied to aspects of life. With the consequent generation of a large number of retired batteries.
In order to improve energy utilization and to protect the environment, it is currently considered to put a large number of retired batteries into an energy storage system for utilization. Because most of retired batteries in the market are different in specification and various in battery model, gradient utilization of retired batteries is a research direction of an energy storage system. For an energy storage system utilizing retired batteries, how to implement consistency management of battery packs inside the energy storage system is a problem to be solved.
Disclosure of Invention
The embodiment of the application provides a distributed energy storage converter and an energy storage system, which can realize consistency management of battery packs with different electrical characteristics.
In a first aspect, an embodiment of the present application provides a distributed energy storage converter, including at least two power grid parallel connection access modules;
each power grid parallel access module comprises at least one converter; each power grid parallel access module comprises a different number of converters; the different power grid parallel connection access modules are used for accessing the battery packs with different characteristic parameters into the power grid;
the battery pack is composed of a plurality of retired batteries, and the characteristic parameters comprise a voltage parameter and a capacity parameter.
In the application, the distributed multi-layer topology is adopted, the battery packs are not directly connected in parallel at the direct current side, all the parallel connection is realized through the converters, and the power grid parallel connection access module corresponding to the characteristic parameters of the battery packs is formed by utilizing a plurality of converters aiming at the battery packs with different characteristic parameters, so that the load distribution and consistency management of the different battery packs based on the plurality of converters can be realized.
In addition, a bidirectional active equalization strategy may also be employed for battery packs to maintain state of charge consistency of the batteries within the battery packs. The battery pack adopts a bidirectional active equalization strategy to keep the consistency of the charge states of the batteries in the battery pack, and different power grid parallel connection access modules can be formed aiming at different characteristic parameters of the battery pack formed by retired batteries.
In a possible implementation manner of the first aspect, the distributed energy storage converter includes a first grid parallel access module and a second grid parallel access module;
the first power grid parallel access module comprises a first-stage converter and a second-stage converter;
the first-stage converter is used for connecting the first battery pack and the direct-current bus; the second-stage converter is used for connecting a direct current bus and an alternating current bus;
the second power grid parallel connection access module is used for accessing a second battery pack to the alternating current bus under the condition of not passing through the direct current bus;
the power supply voltage of the second battery pack is greater than the power supply voltage of the first battery pack, and the battery capacity of the first battery pack is less than or equal to a first capacity threshold.
In the application, for the first battery packs which need to be connected with the direct current bus, the first battery packs are connected with the direct current bus through the first-stage converters, so that when consistency management is carried out, the first-stage converters corresponding to the first battery packs can be used for controlling, and the consistency management of the battery cells is conveniently realized.
In a possible implementation manner of the first aspect, the second grid-parallel access module includes a plurality of third-stage converters; the second battery pack comprises a plurality of first sub-battery packs; the first sub-battery pack is a battery pack with a power supply voltage smaller than a first voltage threshold value;
the plurality of first sub-battery packs are respectively connected with a first alternating current bus through the third-stage converter.
In a possible implementation manner of the first aspect, the second battery pack includes a plurality of second sub-battery packs, and the second grid parallel access module includes a plurality of fourth-stage converters, where the second sub-battery packs are battery packs with a supply voltage between a first voltage threshold and a second voltage threshold;
the plurality of second sub-battery packs are respectively connected with a first alternating current bus through the corresponding fourth-stage converter;
the distributed energy storage converter further comprises a first transformer;
a first end of the first transformer is connected with the first alternating current bus, and a second end of the first transformer is connected with a second alternating current bus; the voltage output by the second alternating current bus is larger than the voltage output by the first alternating current bus.
In a possible implementation manner of the first aspect, the second battery pack further includes a third sub-battery pack, and the second grid parallel access module may further include a plurality of fifth-stage converters; the third sub-battery pack is a battery pack with a power supply voltage greater than the second voltage threshold;
the plurality of third sub-battery packs are respectively connected with a second alternating current bus through the corresponding fifth-stage converter.
In the application, the converters with different levels are respectively arranged corresponding to the battery packs with different power supply voltages, and the power grid parallel connection modules corresponding to the battery packs with different power supply voltages are constructed, so that the battery packs with different characteristic parameters can be controlled and monitored based on the corresponding power grid parallel connection modules, thereby reducing the problem of high consistency management difficulty of the battery packs caused by different retired battery specifications, complicated battery models and various types, and realizing consistency management of the battery packs in the energy storage system.
In a possible implementation manner of the first aspect, the distributed energy storage converter further includes a second transformer and a third transformer;
the first end of the second transformer is connected with the second alternating current bus, and the second end of the second transformer is connected with a third alternating current bus; wherein the voltage output by the third ac bus is greater than the voltage output by the second ac bus;
and the first end of the third transformer is connected with the third alternating current bus, and the second end of the third transformer is connected with a power grid.
In a possible implementation manner of the first aspect, the first battery pack includes a plurality of battery strings, and the first grid parallel access module includes a plurality of first-stage converters corresponding to the plurality of battery strings one to one;
the plurality of battery strings are respectively connected with the direct current buses through corresponding first-stage converters.
In a second aspect, an embodiment of the present application provides an energy storage system, including a cell stack and the distributed energy storage converter of any one of the first aspect;
the battery stack comprises a plurality of battery packs consisting of retired batteries, and different battery packs have different characteristic parameters;
and the distributed energy storage converter connects the different battery packs with the output bus of the energy storage system through corresponding power grid parallel connection access modules.
In a possible implementation manner of the second aspect, the energy storage system includes a plurality of cell stacks;
and a plurality of the battery stacks are connected in parallel to an output bus of the energy storage system through the distributed energy storage converters.
In a possible implementation manner of the second aspect, the energy storage system further includes a battery management system;
the battery management system is respectively connected with the distributed energy storage converter and the battery stack, and is used for controlling the working state of each converter in the distributed energy storage converter and balancing the battery pack in the battery stack based on a bidirectional active balancing strategy.
It will be appreciated that the advantages of the second to fifth aspects may be found in the relevant description of the first aspect, and are not described here again.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments or the description of the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of a distributed energy storage converter according to an embodiment of the present application;
fig. 2 is a schematic architecture diagram of an example of a distributed energy storage converter according to an embodiment of the present application;
fig. 3 is a schematic architecture diagram of another example of a distributed energy storage converter according to an embodiment of the present application;
fig. 4 is a schematic diagram of a distributed energy storage converter according to another embodiment of the present application;
fig. 5 is a schematic architecture diagram of an example of a further distributed energy storage converter provided by an embodiment of the present application;
fig. 6 is a schematic diagram of a distributed energy storage converter according to another embodiment of the present application;
fig. 7 is a schematic diagram of a distributed energy storage converter according to another embodiment of the present application;
FIG. 8 is a schematic diagram of an energy storage system according to an embodiment of the present application;
fig. 9 is a schematic architecture diagram of an example of an energy storage system according to an embodiment of the present application.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.
It should be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It should also be understood that the term "and/or" as used in the present specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.
As used in the present description and the appended claims, the term "if" may be interpreted as "when..once" or "in response to a determination" or "in response to detection" depending on the context. Similarly, the phrase "if a determination" or "if a [ described condition or event ] is detected" may be interpreted in the context of meaning "upon determination" or "in response to determination" or "upon detection of a [ described condition or event ]" or "in response to detection of a [ described condition or event ]".
Furthermore, the terms "first," "second," "third," and the like in the description of the present specification and in the appended claims, are used for distinguishing between descriptions and not necessarily for indicating or implying a relative importance.
Reference in the specification to "one embodiment" or "some embodiments" or the like means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the application. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," and the like in the specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments" unless expressly specified otherwise. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless expressly specified otherwise.
With the increasing application of new energy automobiles in living aspects, a plurality of retired batteries are generated at present. The retired batteries are batteries which cannot meet the power supply requirement of the new energy automobile due to the attenuation of the battery performance, and the recycling of the retired batteries can improve the energy utilization rate and reduce the pollution to the environment.
Energy storage refers to the process of storing energy through a medium or device and releasing the energy when needed. The energy storage system is mostly applied to the aspect of power, such as power guarantee for a power grid, smoothing the power grid, peak clipping and valley filling, and the like.
The retired battery has the characteristics of different specifications, various battery models and various varieties, and how batteries with different specifications, different models and different varieties are applied to the energy storage system provides energy for the energy storage system and stores power grid energy, and the realization of effective balance and consistency management is an important problem to be solved for the energy storage application of the retired battery.
In order to solve the problem of consistency management of battery packs consisting of retired batteries in an energy storage system, the embodiment of the application provides a distributed energy storage converter and an energy storage system, wherein the battery packs are not directly connected in parallel on a direct current side by adopting a distributed multi-layer topology, all the parallel connection is realized through converters, and for battery packs with different characteristic parameters, a power grid parallel connection module corresponding to the characteristic parameters of the battery packs is formed by utilizing a multi-stage converter, load distribution and consistency management are carried out on the different battery packs based on the multi-stage converter, and a bidirectional active balancing strategy can be adopted in the battery packs to keep the consistency of the charge states of the batteries in the battery packs, so that different power grid parallel connection modules can be formed for the different characteristic parameters of the battery packs consisting of retired batteries.
The following describes a distributed energy storage converter provided by an embodiment of the present application with reference to the accompanying drawings:
referring to fig. 1, fig. 1 is a schematic diagram of a distributed energy storage converter according to an embodiment of the present application.
As shown in fig. 1, at least two grid parallel connection modules 12 of the distributed energy storage converter 10 include at least one converter 11, and each grid parallel connection module 12 includes a different number of converters 11.
The different grid parallel connection modules 12 are used for connecting the battery packs 20 with different characteristic parameters into the grid 30.
The input end of the power grid parallel connection access module is used for being connected with the battery pack, and the output end of the power grid parallel connection access module is used for being connected with a power grid.
I.e. different power grid parallel access modules 12 achieve different power conversion and ac-dc conversion by means of different converters 11.
In a specific application, the converter 11 may include a direct current-direct current converter (DC/DC converter), a direct current-alternating current converter (DC/AC converter), a direct current-alternating current converter (DC/AC converter), or the like.
In a specific application, the converter 11 may be an exclusively bi-directional converter. That is, the converter in each power grid parallel connection access module 12 is exclusive to the battery pack connected by the power grid parallel connection access module 12, so that bidirectional control between the power grid and the battery pack can be realized.
In a specific application, the battery pack with different characteristic parameters comprises a plurality of retired batteries, wherein the characteristic parameters comprise a voltage parameter and a capacity parameter.
For example, referring to fig. 2, in an embodiment of the present application, the battery pack includes a battery pack 1 and a battery pack 2, wherein the battery pack 1 is composed of 16 strings of lithium iron phosphate battery modules with nominal capacity of 280Ah, and the battery pack 2 is composed of a ternary battery pack with nominal energy of 70 kWh.
In the application process, a plurality of battery packs 1 are required to be connected in parallel, each battery pack 1 is correspondingly connected with one DC/DC converter 1 (for example, 6.5kW bidirectional DC/DC converter), the other end of each DC/DC converter 1 is connected with a direct current bus (for example, 750V direct current bus), and the direct current bus is connected with an output bus through a DC/AC converter 2 (for example, 600kW bidirectional DC/AC converter). The output bus refers to a bus that outputs electric energy, and the output bus may be an ac bus or a dc bus, and the present application is not particularly limited herein.
Namely, the grid parallel access module 1 for connecting the battery pack 1 in the embodiment of the present application includes a plurality of the above-described converters 1 and 2. For the battery pack 2, it is connected to the output bus by a DC/AC converter 3 (for example a 27kW bi-directional two-stage DC/AC converter); i.e. the grid parallel access module 2 for connecting the battery packs 2 in the embodiment of the application comprises the converter 3 described above.
The two-stage DC/DC/AC converter refers to a converter in which the DC/DC converter and the DC/AC converter are integrated together in two stages. Wherein the output bus outputs energy directly to the outside.
In this example, the output bus may output 380V/50 Hz three-phase electrical parameters, the energy storage system may be a 5MW/10MWh energy storage system, while the number of online battery packs 1 is 120 and the number of battery packs 2 is 350. The energy storage system with the power (transmission power) of 5MW during charging and discharging and the energy storage rated capacity of 10MWh is referred to as the energy storage system with the power of 5MW/10 MWh.
Still further exemplary, referring to fig. 3, in an embodiment of the present application, the battery pack includes a battery pack 3 and a battery pack 4, wherein the battery pack 3 is composed of a ternary battery pack with a nominal energy of 100kWh, and the battery pack 2 is composed of a lithium iron phosphate battery pack with a nominal energy of 300 kWh.
During application, the battery pack 3 is connected to an AC bus 1 (e.g. 380V AC bus) via a DC/AC converter 4 (e.g. 27kW bi-directional two-stage DC/AC converter), the AC bus 1 being connected to an output bus via a step-up transformer 1; i.e. the grid parallel access module 3 for connecting the battery 3 comprises a converter 4 and a step-up transformer 1.
The battery pack 4 is connected to an AC bus 2 (e.g., 690V AC bus) through a DC/AC converter 5 (e.g., 75kW bi-directional DC/AC converter), the AC bus 2 being connected to an output bus through a step-up transformer 2; namely, the grid parallel access module 4 for connecting the battery pack 4 in the embodiment of the present application includes the above-described converter 5 and the step-up transformer 2.
The two-stage DC/DC/AC converter refers to a converter in which the DC/DC converter and the DC/AC converter are integrated together in two stages. Wherein the output bus outputs energy directly to the outside.
In this example, the output bus may output electricity with three-phase electrical parameters of 10 kV/50 Hz, the energy storage system may be a 35MW/100MWh energy storage system, while the number of online battery packs 3 is 750, and the number of battery packs 4 is 200.
An energy storage system of 35MW/100MWh refers to an energy storage system with 35MW of transmission power and 100MWh of energy storage rated capacity.
In the embodiment of the present application, the configuration of different battery packs may be pre-configured, and when the battery packs with different characteristic parameters are correspondingly connected to the corresponding power grid parallel connection access modules 12 through the carrier, so that the battery packs are connected to the power grid for use.
In the embodiment of the application, the number of the converters and the transformers can be configured according to the capacity requirement of the energy storage system, one transformer can be adopted at the same position, a group of multiple transformers can also be adopted to realize, and specific selection can be configured according to the actual condition and the external requirement of the energy storage system, so that the application is not particularly limited.
Therefore, it can be seen that the distributed energy storage converter provided by the embodiment of the application adopts a distributed multi-layer topology, the battery packs are not directly connected in parallel on the direct current side, all the parallel connection is realized through the converter, and aiming at the battery packs with different characteristic parameters, the multi-layer converter is utilized to form a power grid parallel connection access module corresponding to the characteristic parameters of the battery packs, the load distribution and consistency management are carried out on the different battery packs based on the multi-layer converter, the consistency of the charge states of the batteries in the battery packs can be maintained by adopting a bidirectional active balancing strategy in the battery packs, and different power grid parallel connection access modules can be formed aiming at the different characteristic parameters of the battery packs formed by the retired batteries, so that the problem of high difficulty in consistency management of the battery packs caused by different specifications of the retired batteries and various types of the batteries is solved, and the consistency management of the battery packs in the energy storage system is realized.
Referring to fig. 4, fig. 4 is a schematic structural diagram of a distributed energy storage converter according to an embodiment of the present application.
As shown in fig. 4, the distributed energy storage converter includes a first grid parallel access module 121 and a second grid parallel access module 122.
The first grid parallel access module 121 needs to be connected to a dc bus, and the first grid parallel access module 121 may include a first stage converter 111 and a second stage converter 112.
Although the dc bus is connected to the first grid parallel access module 121, the connection is only the connection, and the first grid parallel access module 121 does not include the dc bus.
The first-stage inverter 111 is configured to connect the first battery pack 21 and a dc bus; the second stage converter 112 is used to connect a dc bus with an ac bus.
The first end of the first-stage converter is connected with the first battery pack, the second end of the first-stage converter is connected with the direct current bus, the first end of the second-stage converter is connected with the direct current bus, and the second end of the second-stage converter is connected with the alternating current bus.
When the first-stage converter and the second-stage converter are bidirectional converters, the first end can be used as an input end or an output end, if the first end is used as the input end, the second end is used as the output end, and if the second end is used as the input end, the first end is used as the output end. The input end and the output end can be determined according to practical situations, and the application is not described herein.
The second grid parallel access module 122 is configured to access the second battery pack 22 to the ac bus without going through the dc bus.
Wherein, the power supply voltage of the second battery pack 22 is greater than the power supply voltage of the first battery pack 21, and the battery capacity of the first battery pack 21 is less than or equal to the first capacity threshold.
In the embodiment of the present application, the first capacity threshold may be set according to actual situations.
The first battery pack in the embodiment of the present application is a low-voltage small-capacity battery pack, which may be formed by connecting a plurality of battery strings in series (for example, a 280Ah lithium iron phosphate battery module in the above example), and the second battery pack has a relatively large power supply voltage and may be a battery pack used as a whole (for example, a ternary battery pack with a nominal energy of 70kWh, a ternary battery pack with a nominal energy of 100kWh, a lithium iron phosphate battery pack with a nominal energy of 300kWh, etc.). That is, the power grid parallel connection module in the embodiment of the present application is divided into a power grid parallel connection module (second power grid parallel connection module 122) directly connected to an ac bus and a power grid parallel connection module (first power grid parallel connection module 121) that needs to be connected to a dc bus first and then connected to the ac bus by the dc bus.
Based on this, for the first battery packs that need to be connected to the dc bus, the first level converter 111 is connected to the dc bus first, so that when performing consistency management, control can be performed through the first level converter 111 corresponding to each first battery pack 21, so as to achieve consistency management of the battery cells.
In an embodiment of the present application, the first battery pack 21 includes a plurality of battery strings, and the first grid-parallel access module 121 includes first-stage inverters 111 corresponding to the number of battery strings.
The plurality of battery strings are connected to the dc bus bars through the corresponding first-stage inverters 111, respectively. That is, the distributed energy storage converter 10 includes the first-stage converters 111 corresponding to the number of battery strings included in the first battery pack 21. That is, the first-stage inverter 111 has a first end connected to the battery string and a second end connected to the dc bus.
For example, as shown in fig. 5, if the battery includes 6 first battery packs 21, the distributed energy storage converter 10 includes 6 first-stage converters 111.
In an embodiment of the present application, the first-stage converter 111 is a direct current-direct current converter (DC/DC converter). The type of the first-stage converter can be determined according to an actual application scene, and specifically can be selected according to parameters of the first battery pack and parameters of the direct current bus. For example, the first-stage converter 111 may be a 12.5kW bidirectional DC/DC converter, a 6.5kW bidirectional DC/DC converter, or the like.
In an embodiment of the present application, the second-stage converter 112 is connected between a DC bus and an AC bus, for example, a first end of the second-stage converter 112 is connected to the DC bus, a second end is connected to the AC bus, and the second-stage converter 112 may be a DC-AC converter (DC/AC converter). The specific type of the second-stage converter can be determined according to the actual application scene, and the corresponding second-stage converter can be specifically selected based on parameters of the direct current bus and the alternating current bus, so that the application is not particularly limited. For example, the second stage converter 112 may be a 260MW bi-directional DC/AC converter, a 600kW bi-directional DC/AC converter, or the like.
In an embodiment of the present application, please refer to fig. 6, fig. 6 shows an architecture schematic of a distributed energy storage converter according to another embodiment of the present application. As shown in fig. 6, the second grid parallel access module 122 includes a plurality of third-stage converters 113, a plurality of fourth-stage converters 114, and a plurality of fifth-stage converters 115. The second battery pack 22 includes a plurality of first sub-battery packs 221, a plurality of second sub-battery packs 222, and a plurality of third sub-battery packs 223.
The first sub-battery 221 is a battery with a supply voltage less than a first voltage threshold, the second sub-battery 222 is a battery with a supply voltage between the first voltage threshold and a second voltage threshold, and the third sub-battery 223 is a battery with a supply voltage greater than the second voltage threshold.
The second voltage threshold is greater than the first voltage threshold. The first voltage threshold and the second voltage threshold may be selected according to practical applications, for example, the first voltage threshold is 500V, the second voltage threshold is 1000V, that is, the power supply voltage of the first sub-battery group 221 is less than 500V, the power supply voltage of the second sub-battery group 222 is between 500V and 1000V, and the power supply voltage of the third sub-battery group 223 is greater than 1000V.
The plurality of first sub-battery packs 221 are connected to a first ac bus bar through the third stage converter 113, respectively.
That is, the third-stage inverter 113 has a first terminal connected to the first sub-battery 221 and a second terminal connected to the first ac bus.
That is, in the embodiment of the present application, the number of the third converters 113 is equal to the number of the first sub-battery packs 221, and each of the first sub-battery packs 221 is connected to the first ac bus bar through one third-stage converter 113.
The first ac bus may be a low voltage ac bus, for example, in a 35MW/100MWh energy storage system, the low voltage ac bus is a 380V ac bus.
The plurality of second sub-battery packs 222 are connected to the first ac bus through the corresponding fourth-stage inverters 114, respectively.
Namely, the fourth stage converter has a first end connected to the second sub-battery pack 222 and a second end connected to the first ac bus.
That is, in the embodiment of the present application, the number of the fourth-stage converters 114 is equal to the number of the second sub-battery packs 222, and each of the second sub-battery packs 222 is connected to the first ac bus through one fourth-stage converter 114.
In the embodiment of the present application, the distributed energy storage converter 10 further includes a first transformer 13; a first end of the first transformer 13 is connected to the first ac bus, and a second end of the first transformer 13 is connected to a second ac bus.
In a specific application, the number of the first transformers 13 may be set according to actual needs, for example, one first transformer 13 may be set, or a group of first transformers 13 may be set.
In a specific application, the first transformer 13 is a step-up transformer.
The plurality of third sub-battery packs 223 are connected to the second ac bus bars through the corresponding fifth-stage inverters 115, respectively.
Namely, the fifth-stage inverter 115 has a first terminal connected to the third sub-battery pack and a second terminal connected to the second ac bus bar.
That is, in the embodiment of the present application, the number of the fifth-stage inverters 115 is equal to the number of the third sub-battery packs 223, and each of the third sub-battery packs 223 is connected to the second ac bus bar through one of the fifth-stage inverters 115.
The second ac bus may be a medium voltage ac bus, for example, in a 35MW/100MWh energy storage system, where the medium voltage ac bus is a 690V ac bus. The voltage output by the second alternating current bus is greater than the voltage output by the first alternating current bus.
In an embodiment of the present application, referring to fig. 7, the distributed energy storage converter 10 may further include a second transformer 14 and a third transformer 15; the first end of the second transformer 14 is connected to a second ac bus and the second end of the second transformer 14 is connected to a third ac bus. The first end of the third transformer 15 is connected to a third ac busbar and the second end of the third transformer 15 is connected to the grid.
The voltage output by the third alternating current bus is larger than the voltage output by the second alternating current bus.
The third ac bus may be a high voltage ac bus, that is, the third ac bus may output high voltage.
In a specific application, the number of the second transformers 14 and the third transformers 15 may be set according to actual needs, for example, one second transformer 14 may be set, a group of second transformers 14 may be set, and similarly, one third transformer 15 may be set, or a group of second transformers 15 may be set.
In a specific application, the second transformer 14 is a step-up transformer. The third transformer 15 is a step-up transformer.
It should be noted that, in the embodiment of the present application, the dc bus, the first ac bus, the second ac bus, and the third ac bus may all be output externally.
As can be seen from the above, in the embodiment of the present application, the converters of different levels are respectively provided corresponding to the battery packs of different power supply voltages, and the power grid parallel connection modules corresponding to the battery packs of different power supply voltages are constructed, so that the battery packs of different characteristic parameters can be controlled and monitored based on the corresponding power grid parallel connection modules, thereby reducing the problem of high difficulty in consistency management of the battery packs caused by different retired battery specifications, complicated battery models and various types, and realizing consistency management of the battery packs in the energy storage system.
Based on the distributed energy storage converter, the embodiment of the application also provides an energy storage system. Referring to fig. 8, fig. 8 is a schematic diagram of an architecture of an energy storage system according to an embodiment of the application. As shown in fig. 8, an energy storage system 80 according to an embodiment of the present application may include a cell stack 81 and the distributed energy storage converter 10 in the foregoing embodiments.
In a specific application, the stack 81 may include a plurality of battery packs in the above embodiment, that is, the stack 81 may include the first battery pack 21, the first sub-battery pack 221, the second sub-battery pack 222, and the third sub-battery pack 223.
It will be appreciated that the stack 81 in embodiments of the present application may include more battery packs.
The energy storage system 80 provided by the embodiment of the application can comprise a plurality of battery stacks, so that the energy storage system capable of meeting the power supply requirement is built.
The plurality of battery stacks are connected in parallel to an output bus of the energy storage system through the distributed energy storage converter.
The stack 81 may be a stack of sorted and grouped cells based on a plurality of different models, different specifications, and different varieties of retired cells. Each battery pack can be preassembled and connected through the power grid parallel connection access module 12 provided by the distributed energy storage converter when in use, so that the battery pack is connected into the energy storage core of the energy storage system for working through devices such as a loader. I.e. different battery packs have different characteristic parameters.
The battery stack 81 is connected to an output bus of the energy storage system through the distributed energy storage converter 10, so as to realize an energy storage function.
In a specific application, the distributed energy storage converter connects different battery packs to an output bus of the energy storage system through corresponding power grid parallel connection access modules.
In a specific application, the energy storage system 80 includes a plurality of stacks 81 that can be connected in parallel to the output bus via the distributed energy storage converter or via a power frequency transformer.
Referring to fig. 9, fig. 9 is a schematic architecture diagram of an application example of an energy storage system 80 according to an embodiment of the present application. As shown in fig. 9. The above-described battery stack 81 may include the battery stack 5, the battery stack 6, and the battery stack 7.
Wherein, the battery pack 5 uses a lithium iron phosphate battery pack with a nominal energy of 350 kWh; the battery pack 6 uses a passenger car ternary battery module with nominal energy of 33 kWh; the battery pack 6 uses a passenger car lithium iron phosphate battery pack with a nominal energy of 60 kWh.
The number of battery packs 5 on line at the same time is 1000, the number of battery packs 6 is 20000, and the number of battery packs 7 is 10000 (only one battery pack 5, one battery pack 6, one battery pack 7 are shown as an example in fig. 9).
Each battery pack 5 is connected to a 690V AC bus through 1 120kW bidirectional DC/AC converter.
Each battery 6 is connected to a 1000V DC bus through 1 12.5kW bi-directional DC/DC converter, which is connected to a 690V AC bus through a total power 260MW bi-directional DC/AC converter array.
Each battery 7 is connected to a 380V AC bus through 115 kW bidirectional two-stage DC/AC converter, which is connected to a 690V AC bus through a boost transformer bank 3.
The 690V alternating current bus is connected to an output bus through the distributed boost transformer group 4, and the output bus outputs three-phase electricity with the parameters of 35 kV/50 Hz.
In specific application, the energy storage system provided by the embodiment of the application can output electric energy required by power supply demands by controlling the number of the cell stacks connected to the distributed energy storage converter and selecting the electronic groups with different battery characteristics, and can realize high-value utilization of the retired battery by taking the retired battery as an energy storage raw material, thereby realizing low cost, high benefit and environmental friendliness.
In one embodiment of the present application, the energy storage system 80 may further include a battery management system.
The battery management system is respectively connected with the distributed energy storage converter and the battery stack.
The battery management system can control the working state of each converter in the distributed energy storage converter, so that the load distribution and consistency management of different battery packs are realized.
In an embodiment of the present application, the battery management system equalizes the state of charge consistency of the batteries in the battery pack based on a bidirectional active equalization policy.
In a specific application, the bidirectional active equalization strategy refers to a control strategy for transferring the energy of a battery with a higher charge state in a battery pack to a battery with a lower charge state through the multistage converter (energy storage element), the control switch and the like, so as to achieve the purpose of equalization.
As can be seen from the foregoing, the energy storage system provided in the embodiment of the present application, based on the same inventive concept as the above-mentioned distributed energy storage converter, can also adopt a distributed multi-layer topology, where the battery packs are not directly connected in parallel on the dc side, all the connections are implemented through converters, and for the battery packs with different characteristic parameters, the multi-layer converters are used to form a power grid parallel connection access module corresponding to the characteristic parameters of the battery packs, and load distribution and consistency management are performed on the different battery packs based on the multi-layer converters, and a bidirectional active equalization strategy can be adopted in the battery packs to maintain the consistency of the charge states of the batteries in the battery packs, so that different power grid parallel connection access modules can be formed for the different characteristic parameters of the battery packs formed by retired batteries, thereby reducing the problem of high difficulty in consistency management of the battery packs due to different specifications of the retired batteries, various types and varieties of the battery packs, and implementing the consistency management of the battery packs in the energy storage system.
In the foregoing embodiments, the descriptions of the embodiments are emphasized, and in part, not described or illustrated in any particular embodiment, reference is made to the related descriptions of other embodiments.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
In the embodiments provided in the present application, it should be understood that the disclosed apparatus/network device and method may be implemented in other manners. For example, the apparatus/network device embodiments described above are merely illustrative, e.g., the division of the modules or units is merely a logical functional division, and there may be additional divisions in actual implementation, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection via interfaces, devices or units, which may be in electrical, mechanical or other forms.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
The above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application, and are intended to be included in the scope of the present application.
Claims (8)
1. The distributed energy storage converter is characterized by comprising at least two power grid parallel connection access modules;
each power grid parallel access module comprises at least one converter; each power grid parallel access module comprises a different number of converters; the different power grid parallel connection access modules are used for accessing the battery packs with different characteristic parameters into the power grid;
the battery pack consists of a plurality of retired batteries, and the characteristic parameters comprise voltage parameters and capacity parameters;
the distributed energy storage converter comprises a first power grid parallel connection access module and a second power grid parallel connection access module;
the first power grid parallel access module comprises a first-stage converter and a second-stage converter;
the first-stage converter is used for connecting the first battery pack and the direct-current bus; the second-stage converter is used for connecting the direct current bus and the alternating current bus;
the second power grid parallel connection access module is used for accessing a second battery pack into the alternating current bus under the condition of not passing through the direct current bus;
the power supply voltage of the second battery pack is larger than that of the first battery pack, and the battery capacity of the first battery pack is smaller than or equal to a first capacity threshold;
the second power grid parallel access module comprises a plurality of third-stage converters; the second battery pack includes a plurality of first sub-battery packs; the first sub-battery pack is a battery pack with a power supply voltage smaller than a first voltage threshold;
and the plurality of first sub-battery packs are respectively connected with a first alternating current bus through the third-stage converter.
2. The distributed energy storage converter of claim 1, wherein the second battery pack comprises a plurality of second sub-battery packs, the second grid parallel access module comprises a plurality of fourth stage converters, wherein the second sub-battery packs are battery packs having a supply voltage between a first voltage threshold and a second voltage threshold;
the plurality of second sub-battery packs are respectively connected with a first alternating current bus through the corresponding fourth-stage converter;
the distributed energy storage converter further comprises a first transformer;
the first end of the first transformer is connected with the first alternating current bus, and the second end of the first transformer is connected with the second alternating current bus; and the voltage output by the second alternating current bus is greater than the voltage output by the first alternating current bus.
3. The distributed energy storage converter of claim 1, wherein the second battery pack further comprises a third sub-battery pack, the second grid parallel access module further comprising a plurality of fifth-stage converters; the third sub-battery pack is a battery pack with a power supply voltage greater than the second voltage threshold;
and the plurality of third sub-battery packs are respectively connected with a second alternating current bus through the corresponding fifth-stage converter.
4. A distributed energy storage converter as in claim 3, further comprising: a second transformer and a third transformer;
the first end of the second transformer is connected with the second alternating current bus, and the second end of the second transformer is connected with the third alternating current bus; the voltage output by the third alternating current bus is greater than the voltage output by the second alternating current bus;
and a first end of the third transformer is connected with the third alternating current bus, and a second end of the third transformer is connected with a power grid.
5. The distributed energy storage converter of claim 1, wherein the first battery pack comprises a plurality of battery strings, and the first grid parallel access module comprises a plurality of first stage converters in one-to-one correspondence with the plurality of battery strings;
and the battery strings are respectively connected with the direct current buses through corresponding first-stage converters.
6. An energy storage system comprising a stack and a distributed energy storage converter as claimed in any one of claims 1 to 5;
the battery stack comprises a plurality of battery packs consisting of retired batteries, and different battery packs have different characteristic parameters;
and the distributed energy storage converter connects the different battery packs with the output bus of the energy storage system through corresponding power grid parallel connection access modules.
7. The energy storage system of claim 6, wherein the energy storage system comprises a plurality of stacks;
and a plurality of cell stacks are connected in parallel to an output bus of the energy storage system through the distributed energy storage converters.
8. The energy storage system of claim 6, further comprising a battery management system;
the battery management system is respectively connected with the distributed energy storage converter and the battery stack, and is used for controlling the working state of each converter in the distributed energy storage converter and balancing the battery pack in the battery stack based on a bidirectional active balancing strategy.
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