CN112838608A - Energy storage system - Google Patents
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- CN112838608A CN112838608A CN202110279945.1A CN202110279945A CN112838608A CN 112838608 A CN112838608 A CN 112838608A CN 202110279945 A CN202110279945 A CN 202110279945A CN 112838608 A CN112838608 A CN 112838608A
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- 238000004146 energy storage Methods 0.000 title claims abstract description 314
- 238000006243 chemical reaction Methods 0.000 claims abstract description 140
- 238000010248 power generation Methods 0.000 claims abstract description 76
- 230000009466 transformation Effects 0.000 claims abstract description 14
- 230000008878 coupling Effects 0.000 claims description 86
- 238000010168 coupling process Methods 0.000 claims description 86
- 238000005859 coupling reaction Methods 0.000 claims description 86
- 230000005540 biological transmission Effects 0.000 claims description 2
- 238000012546 transfer Methods 0.000 abstract description 3
- 238000000034 method Methods 0.000 description 10
- 238000010586 diagram Methods 0.000 description 9
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- 230000009471 action Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
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- 238000004891 communication Methods 0.000 description 2
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- 230000002457 bidirectional effect Effects 0.000 description 1
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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
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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
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/466—Scheduling the operation of the generators, e.g. connecting or disconnecting generators to meet a given demand
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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
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/22—The renewable source being solar energy
- H02J2300/24—The renewable source being solar energy of photovoltaic origin
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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
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/28—The renewable source being wind energy
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E70/00—Other energy conversion or management systems reducing GHG emissions
- Y02E70/30—Systems combining energy storage with energy generation of non-fossil origin
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
- Supply And Distribution Of Alternating Current (AREA)
Abstract
The application provides an energy storage system, wherein a new energy power generation module in the energy storage system is connected with the input end of an inverter, and the output end of the inverter is connected with a power grid; the energy storage battery is connected with a power grid through the energy storage current transformation module; the DC/DC conversion module is connected with the input end of the inverter and one end of the energy storage and conversion module, which is connected with the energy storage battery. When the energy storage system is utilized, the new energy power generation module and the energy storage battery box power grid output electric energy, only one-level power conversion is needed, and therefore, the energy transfer efficiency is improved. And when the new energy power generation module charges the energy storage battery, only the DC/DC conversion module is used for power conversion, namely only one-stage power conversion is needed, so that the efficiency of energy storage is improved. In conclusion, the scheme improves the overall efficiency of the energy storage system.
Description
Technical Field
The invention belongs to the technical field of energy storage, and particularly relates to an energy storage system.
Background
In the new energy storage system, a new energy power generation module is connected to a power grid or a micro-grid system through an energy storage converter, and an energy storage battery is connected with the energy storage converter through a DC/DC converter. In the scheme, two-stage power conversion is needed from the energy storage battery to the power grid side, so that the energy transfer efficiency is low, and the efficiency of the whole energy storage system is reduced.
Disclosure of Invention
In view of the above, the present invention provides an energy storage system to solve the problem of low efficiency of the conventional new energy storage system, and the disclosed technical solution is as follows:
an energy storage system, comprising: the system comprises a new energy power generation module, an energy storage battery, a DC/DC conversion module, an inverter and an energy storage conversion module;
the new energy power generation module is connected with the input end of the inverter, and the output end of the inverter is connected with a power grid;
the energy storage battery is connected with the power grid through the energy storage current conversion module;
the DC/DC conversion module is connected with the input end of the inverter and one end of the energy storage conversion module, which is connected with the energy storage battery.
Optionally, the energy storage system comprises at least one of an ac coupling mode, a dc coupling mode, and an ac/dc coupling mode;
when the energy storage system is in an alternating current coupling mode, the DC/DC conversion module does not work, and at least one of the inverter and the energy storage conversion module works;
when the energy storage system is in an alternating current/direct current coupling mode, the DC/DC conversion module, the inverter and the energy storage converter all work, and the DC/DC conversion module is used for realizing energy transmission between an alternating current branch where the inverter is located and an alternating current branch where the energy storage converter module is located;
when the energy storage system is in a direct current coupling mode, the DC/DC conversion module works, and any one of the inverter and the energy storage conversion module works.
Optionally, when the new energy power generation module does not operate, the energy storage converter module operates, the DC/DC conversion module and the inverter do not operate, and the energy storage system is in an ac coupling mode.
Optionally, when the new energy power generation module operates and the output power is less than the rated power of the inverter, the coupling mode of the energy storage system is as follows:
when the energy storage system is in an alternating current coupling mode, the output power of the new energy power generation module supplies power to a power grid through the inverter, and the output power of the energy storage battery supplies power to the power grid through the energy storage current conversion module;
when the energy storage system is in an alternating current/direct current coupling mode and the output power of the energy storage battery is greater than the rated power of the energy storage conversion module, the output power of the energy storage battery enables the residual power after the energy storage conversion module outputs the rated power to be transmitted to the power grid through the DC/DC conversion module and the inverter, and the output power of the new energy power generation module is transmitted to the power grid through the inverter;
when the energy storage system is in a direct current coupling mode, the energy storage current conversion module does not work, the output power of the energy storage battery is transmitted to the power grid through the DC/DC conversion module and the inverter, and the output power of the new energy power generation module is transmitted to the power grid through the inverter.
Optionally, when the new energy power generation module operates and the output power is greater than the rated power of the inverter, the coupling mode of the energy storage system is as follows:
when the energy storage system is in an alternating current coupling mode, the output power of the new energy power generation module is transmitted to the power grid through the inverter, and the output power of the energy storage battery is transmitted to the power grid through the energy storage converter;
when the energy storage system is in an alternating current/direct current coupling mode, the output power of the new energy power generation module enables the residual power after the inverter outputs rated power to be transmitted to the power grid through the DC/DC conversion module and the energy storage conversion module;
when the energy storage system is in a direct current coupling mode, the energy storage current conversion module does not work, the output power of the new energy power generation module enables the inverter to output rated power to the power grid, and the residual power charges the energy storage battery through the DC/DC conversion module.
Optionally, in case of a failure of the inverter, the coupling mode of the energy storage system is as follows:
when the new energy power generation module does not work, the output power of the energy storage battery is transmitted to the power grid through the energy storage converter;
when the new energy power generation module works and the output power is smaller than the power threshold value of the energy storage current transformation module, the output power of the new energy power generation module is transmitted to the power grid through the DC/DC conversion module and the energy storage current transformation module, and the output power of the energy storage battery is transmitted to the power grid through the energy storage current transformation module;
when the new energy power generation module works and the output power is larger than the power threshold of the energy storage current transformation module, the output power of the new energy power generation module is transmitted to the energy storage current transformation module through the DC/DC conversion module, the energy storage current transformation module outputs rated power to the power grid side, and the residual power of the new energy power generation module charges the energy storage battery.
Optionally, when the energy storage converter module fails, the energy storage system is in a direct current coupling mode, the output power of the energy storage battery is output to the power grid through the DC/DC conversion module and the inverter, and the output power of the new energy power generation module is output to the power grid through the inverter.
Optionally, when the DC/DC conversion module fails, the energy storage system is in an ac coupling mode, the output power of the new energy power generation module is output to the grid through the inverter, and the output power of the energy storage battery is output to the grid through the energy storage converter.
Optionally, when the energy storage battery fails, if the output power of the new energy power generation module is smaller than the rated power of the inverter, the output power of the new energy power generation module is output to the power grid through the inverter; and if the output power of the new energy power generation module is greater than the rated power of the inverter, the residual power is transmitted to the power grid through the DC/DC conversion module and the energy storage conversion module.
Optionally, the new energy power generation module comprises at least one of a photovoltaic power generation module and a wind power generation module;
the wind power generation module comprises wind power generation equipment and an inversion module.
Optionally, when the new energy power generation module comprises a photovoltaic power generation module and a wind power generation module, the inverter comprises a first inverter and a second inverter, and the DC/DC conversion module comprises a first DC/DC conversion module and a second DC/DC conversion module;
the wind power generation module is connected with a power grid through the first inverter, and the photovoltaic power generation module is connected with the power grid through the second inverter;
the first DC/DC conversion module is connected to the first inverter and one end of the energy storage conversion module, which is connected with the energy storage battery;
the second DC/DC conversion module is connected to the second inverter and the energy storage converting module and one end of the energy storage battery.
Compared with the prior art, the technical scheme provided by the invention has the following advantages: the new energy power generation module in the energy storage system is connected with the input end of an inverter, and the output end of the inverter is connected with a power grid; the energy storage battery is connected with a power grid through the energy storage current transformation module; the DC/DC conversion module is connected with the input end of the inverter and one end of the energy storage and conversion module, which is connected with the energy storage battery. When the energy storage system is utilized, the new energy power generation module and the energy storage battery box power grid output electric energy, only one-level power conversion is needed, and therefore, the energy transfer efficiency is improved. And when the new energy power generation module charges the energy storage battery, the DC/DC conversion module works, namely only one-stage power conversion is needed, so that the efficiency of energy storage is improved. In conclusion, the scheme improves the overall efficiency of the energy storage system.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a topological diagram of a photovoltaic energy storage system according to an embodiment of the present application;
FIGS. 2 to 7 are topological diagrams of the photovoltaic energy storage system in different operating states respectively;
fig. 8 to 9 are topological diagrams of corresponding operating states when a part of devices in the photovoltaic energy storage system have faults;
FIG. 10 is a topological diagram of a wind energy storage system according to an embodiment of the present application;
fig. 11 to 14 are topological diagrams of corresponding operating states when a part of devices in the wind energy storage system have faults;
FIG. 15 is a topological diagram of a wind and light energy storage system provided by an embodiment of the present application;
FIGS. 16 to 19 are topological diagrams of corresponding operating states of the wind and light energy storage system under different working conditions.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, a topological diagram of an energy storage System according to an embodiment of the present disclosure is shown, and as shown in fig. 1, the energy storage System includes a new energy Power generation module, a battery box, a DC/DC Conversion module, an inverter, and a Power Conversion System (PCS).
For convenience of description and drawing, the number of the devices is illustrated as one, and in practical applications, the number of the devices may be two or more.
In the application scene of photovoltaic power generation, the new energy power generation module can be a photovoltaic power generation module, namely a photovoltaic array; in a wind power generation application scenario, the new energy power generation module includes a wind power generation device (such as a wind power generator) and an inverter.
The output of the new energy power generation module is connected with the input end of the inverter, and the output end of the inverter is connected to the power grid.
In one embodiment of the present application, the inverter includes an inverter and a transformer, and an ac terminal of the inverter is connected to a grid through the transformer.
In one embodiment of the application, a plurality of groups of energy storage batteries are arranged in the battery box, the output of the plurality of groups of energy storage batteries is connected to the output end of the battery box through the current collecting cabinet BCP, and the output of the battery box is connected with a power grid through the PCS.
In one embodiment of the present application, the PCS includes a bidirectional converter and a transformer.
In other embodiments, one or two sets of energy storage batteries may be disposed in the battery box, and the number of the energy storage batteries in the battery box may be set according to the capacity and the actual demand of the energy storage batteries.
The DC/DC conversion module is connected between the inverter and the energy storage and conversion module, wherein one end of the DC/DC conversion module is connected with the input end of the inverter, and the other end of the DC/DC conversion module is connected with one end of the PCS connection battery box.
It should be noted that, control switches are arranged in the three power conversion modules, i.e., the DC/DC conversion module, the inverter and the PCS, and whether the corresponding power conversion module works is controlled by controlling the on-off state of the control switches.
According to the system topology structure of the energy storage system, when the DC/DC conversion module does not work and at least one of the inverter and the energy storage conversion module works, the energy storage system works in an alternating current coupling mode; when the DC/DC conversion module works and the inverter or the energy storage and conversion module does not work, the energy storage system works in a direct current coupling mode; when the DC/DC conversion module, the inverter and the energy storage conversion module work, the energy storage system works in an AC/DC coupling mode. The energy storage system can work in different coupling modes according to different working conditions.
And the energy circulation paths of the energy storage system during normal operation, such as three energy circulation paths from the new energy power generation module to the energy storage battery, from the new energy power generation module to the power grid and from the energy storage battery to the power grid, only need to undergo primary power conversion, so that the loss of system power conversion is reduced, and the system efficiency is improved.
In addition, when the DC/DC conversion module, the inverter or the energy storage conversion module in the energy storage system have faults, the energy storage system can be switched to a coupling mode which does not comprise the power conversion module with the faults, the condition that the energy storage system cannot operate due to the faults of the power conversion module is reduced, and therefore the reliability and the safety of the energy storage system are improved.
In the following, taking a photovoltaic power generation application scenario as an example, different coupling modes of the energy storage system respectively operating under different working conditions are introduced.
1. Normal operation of photovoltaic energy storage system
1) Working at night or without light in daytime
When the photovoltaic energy storage system works at night, the inverter module and the DC/DC conversion module in the photovoltaic energy storage system do not work, the system operates in an alternating current coupling mode, and as shown in figure 2, the energy storage battery performs power conversion through PCS.
When the energy storage battery discharges, the output power of the energy storage battery is converted into alternating current through the PCS and transmitted to a power grid; when the energy storage battery is charged, alternating current on the power grid side is converted into direct current through the PCS to charge the energy storage battery.
Under the conventional condition, the energy storage battery is charged by the power grid at night until the energy storage battery is fully charged, and the system is stopped.
In addition, the energy storage system also operates in the ac coupling mode shown in fig. 2 in the absence of light during the day, and details thereof are not repeated here.
2) The output power of the photovoltaic panel does not reach the rated power of the inverter
Firstly, the photovoltaic energy storage system operates in an alternating current coupling mode
In the alternating current coupling mode, the DC/DC conversion module does not work, and the inverter and the PCS work; in this mode, both the photovoltaic panel and the energy storage battery supply power to the power grid side through primary power conversion until the electric quantity of the energy storage battery is emptied, the energy storage battery quits working, and the working mode is as shown in fig. 3.
As shown in fig. 3, the output power of the photovoltaic panel is converted into alternating current through an inverter to supply power to a power grid; and the output power of the energy storage battery is converted into alternating current through the PCS to supply power to the power grid until the energy storage battery is emptied, and the energy storage battery and the PCS quit working.
Operating the photovoltaic energy storage system in an AC/DC coupling mode
Under the AC/DC coupling mode, the DC/DC conversion module, the inverter and the PCS work. In this mode, the PCS outputs power according to the SOC of the energy storage battery.
If the output power of the energy storage battery is larger than the rated power of the PCS, the output power of the energy storage battery enables the PCS to output the rated power to the power grid, and the rest power is transmitted to the power grid through the DC/DC conversion module and the inverter. Meanwhile, the output power of the photovoltaic panel is converted into alternating current by the inverter and then transmitted to the power grid, as shown in fig. 4.
If the output power of the energy storage battery is smaller than the rated power of the PCS, the energy storage system operates in the ac coupling mode shown in fig. 3, and details thereof are not repeated here.
Operating photovoltaic energy storage system in direct current coupling mode
In the direct-current coupling mode, the PCS stops working, the DC/DC conversion module and the inverter work, the running state is shown in figure 5, and the output power of the photovoltaic panel is transmitted to the power grid after being subjected to power conversion through the inverter; meanwhile, the power output by the energy storage battery is transmitted to the power grid after being subjected to power conversion through the DC/DC conversion module and the inverter.
3) The output power of the photovoltaic panel is larger than the rated power of the inverter
Firstly, the photovoltaic energy storage system works in an alternating current coupling mode
In the ac coupling mode, the DC/DC conversion module does not operate, the PCS outputs power according to the SOC of the energy storage battery, and the inverter operates under the working condition of rated power output, the specific operating state is shown in fig. 3,
secondly, the photovoltaic energy storage system works in an alternating current/direct current coupling mode
Under the AC/DC coupling mode, the DC/DC conversion module, the inverter and the PCS work. In this case, as shown in fig. 6, since the output power of the photovoltaic panel is greater than the rated power of the inverter, the inverter operates in the rated power output condition, and the photovoltaic-side residual power is output to the grid side through the DC/DC conversion module and the PCS. Meanwhile, the output power of the energy storage battery is subjected to power conversion through the PCS and then is supplied to the power grid side, and the PCS outputs power according to the SOC of the energy storage battery.
If the SOC of the energy storage battery is sufficient, the PCS outputs rated power, and the output power of the energy storage battery is as shown in formula 1:
Pbattery with a battery cell＝Ppcs rating-(PPhotovoltaic system-PInverter rating) (formula 1)
If the SOC of the energy storage battery does not meet the output requirement of the formula 1, the energy storage battery outputs the maximum output power according to the SOC, and under the condition, the output power of the PCS is as shown in a formula 2:
Ppcs＝(Pphotovoltaic system-PInverter rating)+Pmax battery(formula 2)
Thirdly, the energy storage system works in a direct current coupling mode
As shown in fig. 7, in the DC coupling mode, the PCS stops operating, the output power of the photovoltaic panel meets the rated output of the inverter, and meanwhile, the photovoltaic side residual electricity is charged to the energy storage battery through the DC/DC conversion module. In the mode, the energy storage battery can be in a full-charged state, and whether the energy storage battery is in the full-charged state or not is determined by specific working conditions of the whole energy storage system.
In the mode, if the energy storage battery can be fully charged, the energy storage battery and the DC/DC conversion module quit working, the inverter still works under the rated output working condition, and the whole photovoltaic energy storage system is in the limited power output mode.
2. Photovoltaic energy storage system fault operation
1) Inverter failure
When the inverter fails, the photovoltaic energy storage system operates in the dc-coupled mode as shown in fig. 8.
Not enough illumination intensity
If the illumination intensity is low, the output power of the photovoltaic panel is low (for example, less than a power threshold of the PCS, and the preset power threshold may be a rated power of the PCS), the DC/DC operates in a maximum power tracking (MPPT) mode, and if the electric quantity of the energy storage battery is sufficient, the PCS can output the rated power, and at this time, the output power of the energy storage battery is as shown in formula 3:
Pbattery with a battery cell＝Ppcs rating-PPhotovoltaic system(formula 3)
If the electric quantity of the energy storage battery is insufficient, outputting the maximum power according to the battery MAP, wherein the output power of the PCS at the moment is shown as a formula 4:
Ppcs＝Pbattery with a battery cell+PPhotovoltaic system(formula 4)
② sufficient illumination intensity
If the illumination intensity is higher, the output power of the photovoltaic panel is higher (for example, greater than or equal to the power threshold of the PCS), that is, the output power of the PCS at the rated power can be satisfied, if the energy storage battery is not fully charged, if the photovoltaic residual power (P) is presentRemainder of＝PPhotovoltaic system-PPCS rating) And if the charging power of the energy storage battery is less than the charging power of the energy storage battery, the DC/DC conversion module works in an MPPT mode, and the residual power of the photovoltaic side charges the energy storage battery. And if the photovoltaic residual power is greater than the battery charging power, the DC/DC conversion module is in a power-limiting output mode.
If the residual power of the photovoltaic side can fully charge the energy storage battery, the energy storage battery stops working; in addition, it should be noted that whether the energy storage battery can be fully charged depends on the operation condition of the energy storage system.
2) PCS failed
When the PCS fails, the photovoltaic energy storage system can operate in the dc-coupled mode as shown in fig. 7.
3) DC/DC conversion module failure
When the DC/DC conversion module fails, the photovoltaic energy storage system can operate in an alternating current coupling mode shown in FIGS. 2 and 3.
4) Failure of energy storage battery
When the energy storage battery fails, the working state of the photovoltaic energy storage system is in an alternating current/direct current coupling mode as shown in fig. 9.
If the illumination intensity is insufficient and the output power of the photovoltaic panel cannot meet the rated output of the inverter, only the inverter works, namely, the alternating current coupling mode is adopted.
If the illumination intensity is sufficient, and the output power of the photovoltaic panel is greater than the rated power of the inverter, the inverter is in a rated output state, and the residual power on the photovoltaic side is output to the power grid after power conversion is performed through the DC/DC conversion module and the PCS, that is, the mode shown in fig. 9.
To sum up, the energy storage system that this application provided can select different coupling modes according to the operating mode of difference to satisfy energy storage system normal operating. Moreover, when partial devices in the energy storage system have faults, the energy storage system can also ensure the energy storage system to be normal, so that the reliability and the safety of the energy storage system are improved.
The topology is also applicable to a wind power generation scene, that is, a wind energy storage system, as shown in fig. 10, the wind energy storage system is different from the photovoltaic energy storage system in that the wind power generation module includes a wind power generator (that is, a fan) and an inverter module, and other parts are the same, and are not described herein again.
Compared with a photovoltaic energy storage system, the wind energy storage system does not need to consider the working time period, and only needs to consider the output power of the fan.
Different coupling modes of the wind energy storage system respectively operating under different working conditions are described below.
1. Normal operation of wind energy storage system
1) Wind power deficiency, PFan blower＜PInverter rating
Under the working condition, the system can select that the PCS does not work, namely the system is in a direct current coupling mode, which is similar to the mode of the figure 5; because the output power of the fan can not lead the inverter to output in a rated mode, the energy storage battery can supplement the residual power, namely the output power of the energy storage battery and the fan ensures the output rated power of the inverter.
When the system selects the DC/DC conversion module not to operate, the system is in the ac coupling mode, similar to the mode shown in fig. 3.
When the system selects that the inverter and the PCS do not work, the fan outputs power according to the SOC of the energy storage battery under the condition that the energy storage battery is not fully charged, and the output power of the fan is converted by the AC/DC module and the DC/DC conversion module and then is charged to the energy storage battery.
2)PInverter rating＜PFan blower＜PInverter rating+Ppcs rating
When the system selects that the PCS does not work, the system is in a direct current coupling mode, the inverter outputs rated power, and the residual power is used for charging the energy storage battery through the DC/DC conversion module.
When the system selects the DC/DC not working, the system is in an alternating current coupling mode, and the inverter outputs at rated power.
When the system selects that the energy storage battery does not work, the system is in an alternating current/direct current coupling mode at the moment, the inverter outputs constant power (rated power), and the residual power of the fan is output to the power grid side after being subjected to power conversion through the DC/DC conversion module and the PCS.
When the system selects an AC/DC coupling mode, under the condition, the energy storage battery does not stop working, the inverter outputs at rated power, and the residual power of the fan flows to the power grid side through the DC/DC conversion module and the PCS. If the electric quantity of the energy storage battery is insufficient, the energy storage battery outputs the maximum power according to the SOC; if the electric quantity of the energy storage battery is sufficient, the PCS outputs rated power.
3)PInverter rating+PPCS rating<PFan blower<PInverter rating+PBattery with a battery cell
When the system selects PCS to be not in work, the system is in a direct current coupling mode. Under the condition, the inverter outputs rated power, the residual power of the fan is used for charging the energy storage battery through the DC/DC conversion module, and the fan outputs limited power.
When the system selects DC/DC not working, the system is in an alternating current coupling mode. In this case, the inverter outputs at a rated power and the fan limits the power.
When the system selects the energy storage battery to stop working, the inverter and the PCS output at rated power.
When the system selects an AC/DC coupling mode, the fan charges the energy storage battery through the DC/DC conversion module according to the power output by the SOC of the battery.
2. Failure of wind energy storage system
1) Inverter failure
When the inverter fails, the operation state of the wind energy storage system is as shown in fig. 11, and different operation states are selected according to the wind power (i.e., the output power of the fan).
If the wind power is insufficient, P is satisfiedFan blower<PPCS ratingThen if PBattery with a battery cell≥PPCS rating-PFan blowerIf yes, outputting rated power of PCS; if the battery is low, PBattery with a battery cell＜PPCS rating-PFan blowerThen P isPCS＝PFan blower+PBattery with a battery cell。
If the wind power is normal, P is satisfiedPCS rating<PFan blower<PPCS rating+PBattery with a battery cellAnd then the residual power of the fan is charged to the energy storage battery through the DC/DC conversion module.
If the wind power is stronger, P is satisfiedPCS rating+PBattery with a battery cell<PFan blowerAnd the fan outputs limited power (the output power is determined according to the charging power of the PCS and the energy storage battery), the PCS rated power is output, and the residual power of the fan after the PCS rated power is output is ensured to charge the energy storage battery.
2) PCS failed
When the PCS fails, the operating state of the wind energy storage system is in the dc coupling mode, as shown in fig. 12, the operating state is the same as the operating state when the PCS in the photovoltaic energy storage system fails, and details are not repeated here.
3) DC/DC conversion module failure
When the DC/DC conversion module fails, the system is in the ac coupling mode shown in fig. 13, which is the same as the operating state of the photovoltaic energy storage system when the DC/DC conversion module fails, and details are not repeated here.
4) Failure of energy storage battery
When the energy storage battery fails, the system is in the ac/dc coupling mode shown in fig. 14.
If the wind power is insufficient, P is satisfiedFan blower<PInverter ratingIf the DC/DC conversion module and the PCS do not work, the inverter outputs.
If the wind power is normal, P is satisfiedInverter rating<PFan blower<PInverter rating+PPCS ratingAnd the inverter outputs rated power, and the residual power flows to the network side through the DC/DC conversion module and the PCS.
If the wind power is stronger, P is satisfiedInverter rating+PPCS rating<PFan blowerThe fan limit power output and the inverter and the PCS rated power output are realized.
In another application scenario of the present application, the energy storage system described above may also be applied to a wind and light energy storage system.
Referring to fig. 15, a topological diagram of a wind and photovoltaic energy storage system provided by an embodiment of the present application is shown, and as shown in fig. 15, the system corresponds to a wind energy storage system and a photovoltaic energy storage system sharing an energy storage battery and a PCS connected to the energy storage battery.
1. Normal operation of the system
1) Working without light (e.g. lower light intensity at night or daytime)
When the wind energy storage system works at night, the system is equivalent to a wind energy storage system, and the running state is as shown in the wind energy storage system, which is not described herein again.
2) Normal working in daytime
①PFan blower<PInverter 1#，PPhotovoltaic system<PInverter 2#
When the output power of the fan is smaller than the rated power of the inverter 1# and the output power of the photovoltaic panel is smaller than the rated power of the inverter 2#, the system operates in the alternating current coupling mode, as shown in fig. 16.
②PFan blower<PInverter 1#，PPhotovoltaic system>PInverter 2#
Under the working condition, the system operates as shown in fig. 17, the DC/DC conversion module at the fan side does not work, that is, the fan side operates in the ac coupling mode; the photovoltaic side and the energy storage battery side are equivalent to a photovoltaic energy storage system, and can work in a direct current coupling mode, an alternating current coupling mode or an alternating current/direct current coupling mode, which is not described herein again.
③PFan blower>PInverter 1#，PPhotovoltaic system<PInverter 2#
Under the working condition, the system operates as shown in fig. 18, the DC/DC conversion module at the photovoltaic side does not work, and the photovoltaic side works in an alternating current coupling mode; the wind side and the energy storage side correspond to a wind energy storage system and can work in an AC/DC coupling mode or a DC coupling mode.
④PFan blower>PInverter 1#，PPhotovoltaic system>PInverter 2#
Under the working condition, the system operation state is as shown in fig. 19, the fan side inverter and the photovoltaic side inverter both output at rated power, meanwhile, the residual power of the fan and the photovoltaic panel preferentially charges the energy storage battery, and when the energy storage battery is full or the residual power is large, the residual power is output to the power grid side through the PCS.
In addition, when a part of devices in the wind and light energy storage system have faults, the situations are the same as the situations of the fault operation described above, and details are not described here.
The wind and light energy storage system provided by the embodiment can select different coupling modes according to different working conditions, and can ensure the normal operation of the energy storage system when partial devices in the system break down, so that the reliability and the safety of the system are improved.
It should be noted that technical features described in the embodiments in the present specification may be replaced or combined with each other, each embodiment is mainly described as a difference from the other embodiments, and the same and similar parts between the embodiments may be referred to each other. For the device-like embodiment, since it is basically similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment.
The steps in the method of the embodiments of the present application may be sequentially adjusted, combined, and deleted according to actual needs.
The device and the modules and sub-modules in the terminal in the embodiments of the present application can be combined, divided and deleted according to actual needs.
In the several embodiments provided in the present application, it should be understood that the disclosed terminal, apparatus and method may be implemented in other manners. For example, the above-described terminal embodiments are merely illustrative, and for example, the division of a module or a sub-module is only one logical division, and there may be other divisions when the terminal is actually implemented, for example, a plurality of sub-modules or modules may be combined or integrated into another module, or some features may be omitted or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or modules, and may be in an electrical, mechanical or other form.
The modules or sub-modules described as separate parts may or may not be physically separate, and parts that are modules or sub-modules may or may not be physical modules or sub-modules, may be located in one place, or may be distributed over a plurality of network modules or sub-modules. Some or all of the modules or sub-modules can be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
In addition, each functional module or sub-module in the embodiments of the present application may be integrated into one processing module, or each module or sub-module may exist alone physically, or two or more modules or sub-modules may be integrated into one module. The integrated modules or sub-modules may be implemented in the form of hardware, or may be implemented in the form of software functional modules or sub-modules.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (11)
1. An energy storage system, comprising: the system comprises a new energy power generation module, an energy storage battery, a DC/DC conversion module, an inverter and an energy storage conversion module;
the new energy power generation module is connected with the input end of the inverter, and the output end of the inverter is connected with a power grid;
the energy storage battery is connected with the power grid through the energy storage current conversion module;
the DC/DC conversion module is connected with the input end of the inverter and one end of the energy storage conversion module, which is connected with the energy storage battery.
2. The energy storage system of claim 1, wherein the energy storage system comprises at least one of an ac coupling mode, a dc coupling mode, and an ac/dc coupling mode;
when the energy storage system is in an alternating current coupling mode, the DC/DC conversion module does not work, and at least one of the inverter and the energy storage conversion module works;
when the energy storage system is in an alternating current/direct current coupling mode, the DC/DC conversion module, the inverter and the energy storage converter all work, and the DC/DC conversion module is used for realizing energy transmission between an alternating current branch where the inverter is located and an alternating current branch where the energy storage converter module is located;
when the energy storage system is in a direct current coupling mode, the DC/DC conversion module works, and any one of the inverter and the energy storage conversion module works.
3. The energy storage system of claim 1, wherein when the new energy power generation module is not operating, the energy storage conversion module is operating, and the DC/DC conversion module and the inverter are not operating, the energy storage system is in an ac coupling mode.
4. The energy storage system of claim 1, wherein when the new energy generation module is operating and the output power is less than the rated power of the inverter, the coupling mode of the energy storage system is as follows:
when the energy storage system is in an alternating current coupling mode, the output power of the new energy power generation module supplies power to a power grid through the inverter, and the output power of the energy storage battery supplies power to the power grid through the energy storage current conversion module;
when the energy storage system is in an alternating current/direct current coupling mode and the output power of the energy storage battery is greater than the rated power of the energy storage conversion module, the output power of the energy storage battery enables the residual power after the energy storage conversion module outputs the rated power to be transmitted to the power grid through the DC/DC conversion module and the inverter, and the output power of the new energy power generation module is transmitted to the power grid through the inverter;
when the energy storage system is in a direct current coupling mode, the energy storage current conversion module does not work, the output power of the energy storage battery is transmitted to the power grid through the DC/DC conversion module and the inverter, and the output power of the new energy power generation module is transmitted to the power grid through the inverter.
5. The energy storage system of claim 1, wherein when the new energy generation module is operating and the output power is greater than the rated power of the inverter, the coupling mode of the energy storage system is as follows:
when the energy storage system is in an alternating current coupling mode, the output power of the new energy power generation module is transmitted to the power grid through the inverter, and the output power of the energy storage battery is transmitted to the power grid through the energy storage converter;
when the energy storage system is in an alternating current/direct current coupling mode, the output power of the new energy power generation module enables the residual power after the inverter outputs rated power to be transmitted to the power grid through the DC/DC conversion module and the energy storage conversion module;
when the energy storage system is in a direct current coupling mode, the energy storage current conversion module does not work, the output power of the new energy power generation module enables the inverter to output rated power to the power grid, and the residual power charges the energy storage battery through the DC/DC conversion module.
6. The energy storage system of claim 1, wherein in the event of a failure of the inverter, the coupling mode of the energy storage system is as follows:
when the new energy power generation module does not work, the output power of the energy storage battery is transmitted to the power grid through the energy storage converter;
when the new energy power generation module works and the output power is smaller than the power threshold value of the energy storage current transformation module, the output power of the new energy power generation module is transmitted to the power grid through the DC/DC conversion module and the energy storage current transformation module, and the output power of the energy storage battery is transmitted to the power grid through the energy storage current transformation module;
when the new energy power generation module works and the output power is larger than the power threshold of the energy storage current transformation module, the output power of the new energy power generation module is transmitted to the energy storage current transformation module through the DC/DC conversion module, the energy storage current transformation module outputs rated power to the power grid side, and the residual power of the new energy power generation module charges the energy storage battery.
7. The energy storage system according to claim 1, wherein when the energy storage converter module fails, the energy storage system is in a DC coupling mode, the output power of the energy storage battery is output to the grid through the DC/DC conversion module and the inverter, and the output power of the new energy power generation module is output to the grid through the inverter.
8. The energy storage system according to claim 1, wherein when the DC/DC conversion module fails, the energy storage system is in an ac coupling mode, the output power of the new energy power generation module is output to the grid through the inverter, and the output power of the energy storage battery is output to the grid through the energy storage converter.
9. The energy storage system according to claim 1, wherein when the energy storage battery fails, if the output power of the new energy power generation module is smaller than the rated power of the inverter, the output power of the new energy power generation module is output to the power grid through the inverter; and if the output power of the new energy power generation module is greater than the rated power of the inverter, the residual power is transmitted to the power grid through the DC/DC conversion module and the energy storage conversion module.
10. The energy storage system of any of claims 1-9, wherein the new energy generation module comprises at least one of a photovoltaic generation module and a wind generation module;
the wind power generation module comprises wind power generation equipment and an inversion module.
11. The energy storage system of claim 10, wherein when the new energy generation module comprises a photovoltaic generation module and a wind generation module, the inverter comprises a first inverter and a second inverter, and the DC/DC conversion module comprises a first DC/DC conversion module and a second DC/DC conversion module;
the wind power generation module is connected with a power grid through the first inverter, and the photovoltaic power generation module is connected with the power grid through the second inverter;
the first DC/DC conversion module is connected to the first inverter and one end of the energy storage conversion module, which is connected with the energy storage battery;
the second DC/DC conversion module is connected to the second inverter and the energy storage converting module and one end of the energy storage battery.
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