CN115566755A - Energy storage system and multi-machine parallel current distribution method - Google Patents
Energy storage system and multi-machine parallel current distribution method Download PDFInfo
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- CN115566755A CN115566755A CN202211181882.7A CN202211181882A CN115566755A CN 115566755 A CN115566755 A CN 115566755A CN 202211181882 A CN202211181882 A CN 202211181882A CN 115566755 A CN115566755 A CN 115566755A
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- 238000000034 method Methods 0.000 title claims abstract description 30
- 238000004146 energy storage Methods 0.000 title claims abstract description 29
- 238000007600 charging Methods 0.000 claims abstract description 70
- 238000007599 discharging Methods 0.000 claims abstract description 43
- 230000036541 health Effects 0.000 claims abstract description 10
- 230000001105 regulatory effect Effects 0.000 claims abstract description 6
- 239000002253 acid Substances 0.000 claims description 21
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 19
- 229910052744 lithium Inorganic materials 0.000 claims description 19
- 230000002457 bidirectional effect Effects 0.000 claims description 11
- 230000001276 controlling effect Effects 0.000 claims description 4
- 230000009467 reduction Effects 0.000 claims description 3
- 238000007726 management method Methods 0.000 claims 3
- 101100388636 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) ECM21 gene Proteins 0.000 description 14
- 230000005611 electricity Effects 0.000 description 4
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 4
- 238000004891 communication Methods 0.000 description 3
- 238000010280 constant potential charging Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 238000010277 constant-current charging Methods 0.000 description 2
- 238000007667 floating Methods 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
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- 238000004870 electrical engineering Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000012163 sequencing technique Methods 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
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/007—Regulation of charging or discharging current or voltage
- H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
- H02J7/00714—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters in response to battery charging or discharging current
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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
- H02J7/00032—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries characterised by data exchange
- H02J7/00036—Charger exchanging data with battery
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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
- H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
- H02J7/0048—Detection of remaining charge capacity or state of charge [SOC]
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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
- H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
- H02J7/005—Detection of state of health [SOH]
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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
- H02J7/0068—Battery or charger load switching, e.g. concurrent charging and load supply
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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
- H02J7/02—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from ac mains by converters
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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
- H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
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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
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
- H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
- H02M3/1582—Buck-boost converters
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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 invention provides an energy storage system and a multi-machine parallel current distribution method, wherein the system comprises: the rectifier AC/DC converts commercial power into direct current and then is connected to the bus bar; the battery cabinet comprises a relay, a plurality of battery plug-in boxes and an edge intelligent gateway ECM, wherein the battery plug-in boxes are connected to a bus bar in parallel, each battery plug-in box comprises a power type battery management system PBMS and an electric core, and the voltage of each electric core is regulated by the PBMS and then is converged to the bus bar. The ECM automatically distributes charging and discharging currents of a single battery plug box according to the capacity Q, the battery state of charge SOC and the battery state of health SOH of the battery plug box, so that all the battery plug boxes are charged or discharged at the same time. Meanwhile, a multi-machine parallel current distribution method is designed, and charging and discharging currents can be automatically distributed according to the states of all battery plug boxes, so that all the battery plug boxes are fully charged or emptied at the same time. The invention can realize the mixed use of new and old batteries with different types and capacities.
Description
Technical Field
The invention relates to the field of electrical engineering, in particular to an energy storage system and a multi-machine parallel current distribution method.
Background
The construction of a backup power supply system of a communication base station is traditionally carried out by adopting a lead-acid storage battery scheme. In recent years, with the gradual reduction of the price of lithium batteries, lithium iron phosphate batteries in particular have the characteristics of better safety, higher energy density than that of lead-acid batteries, longer cycle life and lower operation and maintenance cost, so that all telecom operators adopt the lithium iron phosphate batteries in batches to replace the original lead-acid batteries. Meanwhile, the energy storage market of the 5G base station is gradually increased, and the lithium iron phosphate battery system applied to peak clipping and valley filling is more and more greatly put into the base station to operate.
These changes lead to situations that battery packs with different capacities coexist and operate in a mixed mode at different times or batches in the current communication base station. In order to protect the existing investment of a base station to the maximum extent, fully utilize the battery resources of the base station, achieve the purpose of mixing different types and batches of battery packs, and ensure the safety and the convenience of the confluence of the battery packs, a battery system needs to be designed, a charging and discharging current distribution method needs to be designed according to the working condition that a plurality of battery plug boxes of the battery system are connected in parallel, and the battery system can be compatible with lead acid for use.
Secondly, in the traditional energy storage system, different types of batteries (such as lead-acid and lithium iron phosphate batteries) are mixed, so that the lithium battery cabinet is directly connected with the lead-acid in parallel and charged and discharged simultaneously, the cycle life of a common lithium battery is more than 5 times of that of the lead-acid, and the lead-acid battery needs to be frequently replaced, and the site maintenance is not facilitated.
Disclosure of Invention
In view of the above drawbacks of the prior art, an object of the present invention is to provide an energy storage system and a multi-machine parallel current distribution method, which are used to solve the problem that when a conventional energy storage system is used in parallel, each battery box is charged according to a preset charging current limit value under a charging condition, and the charging current value cannot be automatically adjusted according to the battery state during the system use process. The invention can also solve the problem that the discharging current of each battery plug box is uncontrollable under the discharging working condition. The charging and discharging current Of a single battery plug box can not be automatically distributed according to the capacity (Q) Of the battery plug box, the SOC (State Of Charge) and the SOH (State Of Health) Of the battery, so that the problems that each battery plug box is full Of and emptied at the same time, the utilization rate Of the battery is maximized, and the lead-acid battery needs to be frequently replaced are solved.
To achieve the above and other related objects, the present invention provides an energy storage system, comprising:
the rectifier AC/DC converts commercial power into direct current and then is connected to the bus bar;
the battery cabinet comprises a relay, a plurality of battery plug boxes connected in parallel on the bus bar and an edge intelligent gateway ECM (electronic control module), wherein each battery plug box comprises a power type battery management system (PBMS) and a battery cell, and the voltage of each battery cell is regulated by the PBMS and then is converged on the bus bar;
the ECM automatically distributes charging and discharging currents of the single battery plug boxes according to the capacity Q, the battery state of charge SOC and the battery state of health SOH of the battery plug boxes, so that the battery plug boxes are fully charged or fully discharged at the same time.
In one embodiment of the present invention, the power type battery management system PBMS includes a bi-directional DC/DC converter and a battery management system BMS, the PBMS and the ECM are networked by a controller area network CAN, and the ECM individually controls each of the battery boxes to achieve a desired charging and discharging current value.
In an embodiment of the invention, the bidirectional DC-to-DC converter is a bidirectional Buck-Boost topology.
In an embodiment of the present invention, the ECM interacts with each of the battery boxes through the CAN, collects status information of each of the battery boxes, and then sends a voltage parameter to each of the battery boxes, and simultaneously sends a current and a charge/discharge command to each of the battery boxes individually.
In an embodiment of the invention, the ECM further includes a backup battery, and the ECM controls the relay to disconnect the battery box from the backup battery when the ECM needs to operate.
In an embodiment of the present invention, in a battery box priority mode, when discharging is required, the ECM controls the relay to be turned off, the backup battery is offline, the DC/DC converter operates in a boost discharging mode, when the voltage of the bus bar is slightly higher than the AC/DC set output voltage, the AC/DC output is turned off, all the energy consumed by the external load is provided by the battery box, and when the battery box is continuously discharged, the voltage of the bus bar is maintained; when charging is needed, the voltage of the bus bar is kept unchanged, the DC/DC converter firstly works in a voltage reduction charging mode, and when the voltage of the battery plug box is increased to be equal to or higher than the voltage of the bus bar, the voltage is switched to a voltage boosting charging mode.
In an embodiment of the present invention, the battery box may be a lithium battery box, and the standby battery may be a lead-acid battery or a lithium battery.
The invention further provides a method for multi-machine parallel current distribution of an energy storage system according to the above, characterized in that: the method comprises the following steps:
s100, calculating the charge and discharge current value of each battery plug-in box according to the capacity Q of the battery plug-in box, the state of charge SOC (state of charge) of the battery and the SOH (state of health) of the battery;
s101, judging whether the energy storage system is in a state of needing to be charged or discharged;
s102, comparing the charge-discharge current value obtained through calculation with the maximum charge-discharge current allowed by the current state of each battery plug box, taking the smaller value as the charge-discharge current of the battery plug box, and sending a charge-discharge instruction to the single battery plug box;
s103, when one battery plug box is full, emptied or can not be charged or discharged due to faults, controlling the battery plug box to finish charging or finish discharging without influencing the charging and discharging operation of other battery plug boxes.
In an embodiment of the present invention, the step S100 includes the following steps:
arranging the SOC of each battery inserting box from low to high;
selecting the intermediate value of the SOC as an initial SOC (SOC initial), taking Ibenchmark =0.35C as a reference charging current, taking Qpresent = Qinitial SOH as present Q, and calculating reference time Tbenchmark required by the battery plug-in box to charge and discharge to a target SOC (SOC target);
calculating the charging and discharging current Ix of each battery plug box according to the reference time T;
wherein 1C represents the current intensity in a unit a at which the battery is completely discharged for one hour; and Q is the factory output capacity of the battery in Ah.
In an embodiment of the present invention, the T Reference(s) The calculation formula of (2) is as follows: t is a unit of Reference(s) = said Q At present * (| the SOC Target -said SOC Initial I)/the I Datum The calculation formula of the charge and discharge current Ix is as follows: ix = Qx At present *(|SOCx Target -SOCx Initial |)/T Datum 。
As described above, the energy storage system and the multi-machine parallel current distribution method of the invention have the following beneficial effects: the battery can be charged or discharged, and the voltage can be increased or decreased. The built-in marginal intelligent gateway ECM of battery cabinet, steerable lead acid cuts off, lets the system work in the priority mode of lithium cell, avoids reserve battery (lead acid battery or lithium cell) long-term floating charge, saves the charges of electricity, improves the life-span, reduces reserve battery (lead acid battery or lithium cell) and changes the frequency. Can be based on the current capacity Q of the battery At present The battery state of charge SOC and the battery state of health SOH automatically distribute charging and discharging current, so that different battery plug boxes are charged or discharged to a target SOC value simultaneously, and sharing of different types, different capacities, new batteries and old batteries is realized.
Drawings
Fig. 1 is a schematic diagram of an energy storage system according to the present invention.
Fig. 2 is a schematic flow chart of a method for multi-machine parallel current distribution according to the present invention.
Fig. 3 is a schematic flow chart illustrating a charging current distribution method in the multi-machine parallel current distribution method according to the present invention.
Fig. 4 is a schematic flow chart illustrating a discharge current distribution method in the multi-parallel current distribution method according to the present invention.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict. It is also to be understood that the terminology used in the examples is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. Test methods in which specific conditions are not noted in the following examples are generally performed under conventional conditions or conditions recommended by each manufacturer.
Please refer to fig. 1 to 4. It should be understood that the structures, ratios, sizes, etc. shown in the drawings and attached to the description are only for understanding and reading the disclosure of the present invention, and are not intended to limit the practical conditions of the present invention, so that the present invention has no technical significance, and any modifications of the structures, changes of the ratio relationships, or adjustments of the sizes, should still fall within the scope of the technical contents disclosed in the present invention without affecting the efficacy and the achievable purpose of the present invention. In addition, the terms "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms is not to be construed as a scope of the present invention.
Referring to fig. 1, the present invention provides an energy storage system, which includes a rectifier AC/DC (alternating current/direct current) 1 and a battery cabinet 2 connected to a bus bar 4. A plurality of parallel battery plug boxes (in an embodiment of the present invention, lithium battery plug boxes, and other suitable battery plug boxes) 25 are disposed inside the battery cabinet 2, each battery plug box 25 includes a power type battery management system PBMS28 and a battery pack composed of a plurality of battery cells 24, and each PBMS28 includes a bidirectional DC-to-DC/DC converter 29 (hereinafter referred to as DC/DC 29) and a battery management system BMS27. The bidirectional DC/DC29 is a bidirectional Buck-Boost circuit Buck-Boost topological structure and is connected with the battery management system BMS27 through serial communication 26. Each battery box 25 is connected to one end of the edge smart gateway ECM21 via a controller area network CAN23, and the other end of the ECM21 is connected to the relay 22. The edge smart gateway ECM21 controls the on/off of the backup battery (lead-acid battery pack in the following embodiment) 3 through a relay 22.
The working principle of the energy storage system is as follows: the rectifier AC/DC1 converts commercial power into direct current and then connects the direct current to the bus bar 4. The battery cabinet 2 comprises a relay 22, a plurality of battery plug boxes connected in parallel on the bus bar 4 and an edge intelligent gateway ECM21, the battery plug boxes comprise a power type battery management system PBMS28 and battery cells 24, and the voltage of the battery cells 24 is regulated by the PBMS28 and then is converged on the bus bar 4. The ECM21 automatically allocates the charging and discharging currents of the individual battery boxes 25 according to the capacity Q, the state of charge SOC, and the state of health SOH of the battery boxes, so that the respective battery boxes are charged or discharged at the same time.
Specifically, the rectifier AC/DC1 converts commercial power into direct current and then connects the direct current to the bus bar 4, and the voltages of the battery cells 24 in each battery box 25 are regulated by the bidirectional DC/DC29 and then collected to the battery cabinet 2, and further collected to the bus bar 4. In the battery plug box priority mode (i.e. in the case of priority use of the battery plug box 25), when discharge is required, the ECM21 controls the relay 22 to be turned off, the lead-acid battery pack 3 is turned off, the bidirectional DC/DC29 operates in the boost discharge mode, the battery plug box 25 and the AC/DC1 supply power to an external load (not shown in the figure) at the same time, the power supply duty ratio with high voltage is large, the voltage of the bus bar 4 is slightly higher than the set output voltage of the AC/DC1, and the AC/DC1 output is turned off (i.e. when the voltage of the lithium battery plug box 25 is higher than the set voltage of the AC/DC1, current is mainly supplied by the battery plug box 25, and when the voltage difference is greater than a certain threshold, the energy consumed by the external load is completely supplied by the battery plug box 25). The voltage of the bus bar 4 can be maintained constant while the battery box 25 is continuously discharged. When charging is required, the voltage of the bus bar 4 is maintained (the AC/DC maintains the voltage of the bus bar 4 at a preset output voltage), the bidirectional DC/DC29 operates in the step-down charging mode, and when the voltage of the battery box 25 is increased to be equal to or higher than the voltage of the bus bar 4, the charging mode is switched to the step-up charging mode. The ECM21 interacts with each battery box 25 through the CAN23, collects the states of the battery boxes 25, sends voltage parameters to each lithium battery box 25, and simultaneously sends current and charge and discharge instructions to each battery box 25 independently.
The operation logic (flow) of the multi-machine parallel current distribution method of the invention is shown in fig. 2, and specifically comprises the following steps:
s100, calculating the charge and discharge current value of each battery plug box 25 according to the capacity Q, the battery state of charge SOC and the battery state of health SOH of the battery plug box 25;
the method specifically comprises the following steps: arranging the SOC of each battery box 25 from low to high;
selecting an intermediate value of SOC as an initial SOC (SOC) Initial ) Charging current is based on I reference =0.35C and Q is based on At present ＝Q Initial * SOH is the current Q to calculate the charging and discharging of the battery box 25 to the target SOC (SOC) Target ) Required reference time T Datum ；
According to the reference time T Datum Calculating the charging and discharging current Ix of each battery plug box 25;
wherein 1C represents the current intensity in a unit a at which the battery is completely discharged for one hour; and Q is the factory output capacity of the battery in Ah.
Further, the S100 step further includes the steps of:
s101: judging whether the energy storage system is in a state of needing charging or needing discharging;
s102: respectively comparing the charge-discharge current value obtained by calculation with the maximum charge-discharge current allowed by the current state of each battery plug-in box 25, taking the smaller value as the charge-discharge current of the battery plug-in box 25, and respectively sending a charge-discharge instruction to the single battery plug-in box 25;
s103: when one battery plug box 25 is full or empty or can not be charged or discharged due to faults, the battery plug box 25 is controlled to finish charging or discharging, and the charging and discharging operation of other battery plug boxes 25 is not influenced.
S104: the charge/discharge is ended.
In the multi-machine parallel current distribution method of the invention, the flow of the charging current distribution method is shown in fig. 3, and the details are as follows:
s201: sorting the SOC of the battery plug-in boxes, and taking the intermediate value as the initial SOC Initial ；
S202: checking SOC, obtaining the maximum charging current allowed by the current state of the battery plug-in box 25 by the temperature table, comparing the maximum charging current with the set 0.35C current value, and taking the smaller value as the charging current I of the plug-in box Reference(s) ；
S203: according to I Datum Calculating the time T for charging the battery box 25 to the target SOC Datum ，T Datum (| SOC target-SOC) = QCurrent | (| SOC target-SOC Initial |)/I Datum ；
S204: according to T Datum Calculating the charging current of other battery plug-in boxes 25, comparing the charging current with the maximum allowable charging current of the battery plug-in box 25, and taking the smaller value as the charging current of the battery plug-in box 25;
s205: and finishing charging.
As shown in fig. 4, in the multi-machine parallel current distribution method of the present invention, the method flow for distributing the discharging current specifically includes the following steps:
s301: the battery plug-in boxes 25 are sorted according to SOC, and the intermediate value is taken as the initial SOC Initial ；
S302: checking SOC, obtaining the maximum current allowed to discharge of the battery plug-in box 25 by a temperature table, comparing with 0.35C, and multiplying a small value by an SOH factor to be used as the discharge current I of the battery plug-in box 25 Reference for discharge ；
S303: according to I Reference for discharge Calculating the time T for charging the battery box 25 to the target SOC Reference for discharge ；
S304: according to T Reference for discharge Calculating discharge power of other battery plug-in boxesComparing the current with the maximum current allowed to discharge by the plug box, and taking a small value;
s305: when discharging is started, the current limiting values of all the battery plug boxes 25 are set to be the maximum discharging current value allowed by the current state of the plug box, and the discharging current of the battery plug box with high electric quantity and small internal resistance is higher;
s306: accumulating the discharging current allowed by the battery plug-in box 25 calculated in the step S304 to obtain the allowed discharging current I of the battery cabinet 2 Allowing discharge Accumulating the current of the S305 battery plug box to obtain I Current discharge of electricity Obtaining the coefficient K = I Current discharge of electricity /I Allowing discharge of electricity ；
S307: sequencing the battery box 25 current from high to low;
s308: regulating the discharging current limit of the half battery plug box with higher current to the calculated current value in KxS 304;
the half of the battery box with the higher current is the battery box with the current value above the median value in all the battery boxes according to the arrangement result in step S307.
S309: executing the step S308 on the remaining half of the battery plug-in boxes until the number of the remaining battery plug-in boxes is less than or equal to 2;
the remaining half of the battery box is the battery box from which the battery box with higher current described in the previous step S308 was removed. Since the load (external consumer, not shown) current will increase, the last 2 battery boxes will not be current limited in response to changes in load current.
S310: the discharge is ended.
In specific application of the invention, the rectifier AC/DC1 can be a charging module, and the voltage of the charging module is kept unchanged after parameters are set. In the charging mode, when the AC/DC1 voltage is higher than the total voltage of the battery cells 24 in the battery box 25, the DC/DC29 operates in the step-down mode to charge the battery box 25. If the AC/DC1 voltage is lower than the total voltage of the electric cores 24 in the battery plug box 25, the DCDC29 works in a boosting mode to fully charge the battery plug box 25, and the ECM21 controls charging and discharging according to strategies and time intervals to achieve the purposes of peak clipping, valley filling and standby power. The DC/DC29 can adjust the output voltage and current of the battery box 25 by controlling the buck-boost mode, switching frequency and duty cycle. If the battery plug box is charged, parameters can be sent to the battery plug box 25 through the controller ECM21, the DC/DC29 is arranged in the battery plug box 25, the battery can be charged at constant current or constant voltage (the charging end uses constant voltage charging), and in the constant current charging mode, the charging current can be dynamically adjusted according to instructions issued by the ECM (10A, 20A or 30A).
The energy storage system is normally in the lithium battery compartment 25 priority mode. During discharge, the ECM21 turns off the relay 22, isolating the lithium battery pack and the lead-acid battery pack 3. When the mains supply is powered off, the relay 22 is in an actuation state, the lithium battery pack firstly maintains the voltage of the bus bar 4 at a floating charge voltage point (generally 54.6V) of the lead-acid battery 3, after the lithium battery discharges to a preset discharge depth, the lithium battery finishes discharging, the lead-acid battery 3 continues discharging, and the voltage of the bus bar 4 is gradually reduced along with the increase of the discharge depth of the lead-acid battery 3.
For example: the voltage of the bus bar 4 can be 54.6V all the time, when the battery plug box 25 discharges to a cut-off voltage point, the total voltage of the battery cells 24 in the battery plug box 25 is 44V, when the bus bar 4 with higher voltage charges the battery cells 24 in the battery plug box 25 with lower voltage, the DCDC29 arranged in the battery plug box 25 reduces the voltage of the bus bar 4 to be slightly higher than the total voltage of the battery cells 24, and the charging current reaches a preset value by controlling the voltage difference between the total voltage of the battery cells 24 and the side of the DCDC29 close to the battery cells 24. When the total voltage of the battery cells 24 in the lithium battery plug box 25 slowly rises to a voltage close to 54.6V in the charging process, the DCDC29 raises the voltage of the bus bar 4 to a value slightly higher than the total voltage of the battery cells 24, and constant-current charging is continued. When the battery cell 24 is charged to the end, the DCDC29 boosts the voltage of the bus bar 4 to the total voltage overcharge protection point 58.4V of the battery cell 24, switches to the constant voltage charging mode, and the charging current gradually decreases as the total voltage of the battery cell 24 gradually increases. In the whole charging process, voltage is firstly reduced and then increased, and when the charging tail end is switched to a constant voltage charging mode to discharge, the ECM21 controls the relay 22 to disconnect the lead-acid battery (the backup battery 3).
During charging, the charging currents of the other battery boxes are calculated by using the SOC intermediate values of the plurality of battery boxes 25 and the charging currents allowed to the battery boxes 25 as reference values, and the battery boxes 25 can be charged to a preset SOC. Specifically, a plurality of battery boxes 25 are connected in parallel, and each battery box 25 is collectively managed by the ECM 21. If the charging current is not distributed, because the initial SOC difference is large, in order to achieve the purpose that each battery plug-in box 25 can be fully charged and the SOC keeps consistent or the difference is reduced, the charging current of each battery plug-in box 25 is different by adjusting the charging current. Each battery box 25 is individually controlled by the ECM21 until it is eventually able to be simultaneously charged or simultaneously reach a preset SOC value. And if the charging is not allowed in the current time period, finishing the charging of all the battery plug-in boxes.
During discharging, the battery plug-in box with different capacities can be compatible. At the beginning, all battery plug boxes do not limit current, then the current limiting values of all battery plug boxes are set as the maximum discharging current values allowed by the current state of the plug box, and half of the battery plug boxes with higher current in all the battery plug boxes are sequentially limited in current, wherein the discharging current of the battery plug boxes with high power and small internal resistance is higher, and 2 battery plug boxes are reserved for not limiting current in order to respond to the change of load current because the current of a load (external electrical equipment) fluctuates. If the ECM21 limits all of the battery boxes 25, when the load current suddenly increases, the total discharge current of the battery boxes reaches the limit value, and the load power requirement cannot be met, then the AC/DC1 will intervene in the discharge, which is not in accordance with the design requirement of the present application that all current is supplied by the battery boxes 25 and the AC/DC does not intervene in the discharge. The discharging distribution method can distribute current according to the battery state. The current is distributed by the ECM21 according to the capacity, state of charge, and state of health of each battery box 25. The plurality of battery plug boxes 25 have high electric quantity, large capacity, good multi-discharge in a healthy state, low electric quantity, small capacity and poor low-discharge in a healthy state, and the battery plug boxes 25 are ensured to be emptied simultaneously. The charge and discharge control is integrally managed in the ECM 21. Two battery plug boxes 25 can be kept without current limiting during discharging, and timely response can be realized when the external load is increased.
In summary, the invention provides an energy storage system, which can realize the mixed use of new and old batteries with different types and capacities; meanwhile, a current distribution method is provided, and charging and discharging currents can be automatically distributed according to the states of the battery plug boxes, so that the battery plug boxes can be fully charged and emptied at the same time. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Those skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which may be made by those skilled in the art without departing from the spirit and scope of the present invention as defined in the appended claims.
Claims (10)
1. An energy storage system, comprising:
the rectifier AC/DC converts commercial power into direct current and then is connected to the bus bar;
the battery cabinet comprises a relay, a plurality of battery plug boxes connected in parallel on the bus bar and an edge intelligent gateway ECM (electronic control module), wherein each battery plug box comprises a power type battery management system (PBMS) and a battery cell, and the voltage of each battery cell is regulated by the PBMS and then is converged on the bus bar;
the ECM automatically distributes charging and discharging currents of the single battery plug-in boxes according to the capacity Q, the battery state of charge SOC and the battery state of health SOH of the battery plug-in boxes, so that the battery plug-in boxes are charged or discharged at the same time.
2. The energy storage system of claim 1, wherein: the power type battery management system PBMS comprises a bidirectional direct current to direct current DC/DC converter and a battery management system BMS, the PBMS and the ECM are networked through a controller area network CAN, and the ECM controls each battery plug box individually to enable the charging current and the discharging current to reach the expected current values.
3. The energy storage system of claim 2, wherein: the bidirectional direct current-to-direct current DC/DC converter is of a bidirectional Buck-Boost topological structure.
4. The energy storage system of claim 2, wherein: the ECM interacts with the battery plug boxes through the CAN, collects the state information of the battery plug boxes, sends voltage parameters to the battery plug boxes, and simultaneously sends current and charging and discharging instructions to each battery plug box independently.
5. The energy storage system of claim 4, wherein: the ECM controls the relay to disconnect the battery plug box from the backup battery when the battery plug box needs to work.
6. The energy storage system of claim 5, wherein: when the battery plug box is in a priority mode and needs to discharge, the ECM controls the relay to be switched off, the standby battery is off-line, the DC/DC converter works in a boost discharge mode, when the voltage of the bus bar is slightly higher than the AC/DC set output voltage, the AC/DC output is switched off, the energy consumed by an external load is completely provided by the battery plug box, and when the battery plug box continuously discharges, the voltage of the bus bar is kept unchanged; when charging is needed, the voltage of the bus bar is kept unchanged, the DC/DC converter firstly works in a voltage reduction charging mode, and when the voltage of the battery plug box is increased to be equal to or higher than the voltage of the bus bar, the DC/DC converter is switched to a voltage boosting charging mode.
7. The energy storage system of claim 6, wherein: the battery plug box can be a lithium battery plug box, and the standby battery can be a lead-acid battery or a lithium battery.
8. A multi-machine parallel current distribution method for the energy storage system according to any one of claims 1 to 7, characterized in that: the method comprises the following steps:
s100, calculating the charge and discharge current value of each battery plug box according to the capacity Q of the battery plug box, the battery electric quantity state SOC and the battery health state SOH;
s101, judging whether the energy storage system is in a state of needing to be charged or discharged;
s102, comparing the charge-discharge current value obtained through calculation with the maximum charge-discharge current allowed by the current state of each battery plug box, taking the smaller value as the charge-discharge current of the battery plug box, and sending a charge-discharge instruction to the single battery plug box;
s103, when one battery plug box is full, emptied or can not be charged or discharged due to faults, controlling the battery plug box to finish charging or finish discharging without influencing the charging and discharging operation of other battery plug boxes.
9. The multi-machine parallel current distribution method of an energy storage system according to claim 8, wherein: the step S100 includes the steps of:
arranging the SOC of each battery plug-in box from low to high;
selecting an intermediate value of the SOC as an initial SOC (SOC) Initial ) In the first place Datum Charge current of 0.35C, Q At present ＝Q Initial * SOH is the current Q to calculate the charging and discharging of the battery plug box to the target SOC (SOC) Target ) Required reference time T Datum ；
According to the reference time T Reference(s) Calculating the charging and discharging current Ix of each battery plug box;
wherein 1C represents the current intensity in a unit a at which the battery is completely discharged for one hour; q Initial The battery delivery capacity is the unit Ah.
10. The multi-machine parallel current distribution method of an energy storage system according to claim 9, wherein: said T is Datum The calculation formula of (2) is as follows: t is Reference(s) = said Q At present * (| the SOC Target -said SOC Initial I)/the I Reference(s) The calculation formula of the charge and discharge current Ix is as follows: ix = Qx At present *(|SOCx Target -SOCx Initial |)/T Datum 。
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117220384A (en) * | 2023-11-08 | 2023-12-12 | 江苏纳通能源技术有限公司 | Current distribution method for parallel operation of batteries and battery parallel system |
| CN117220384B (en) * | 2023-11-08 | 2024-02-09 | 江苏纳通能源技术有限公司 | Current distribution method for parallel operation of batteries and battery parallel system |
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Effective date of registration: 20240315 Address after: 335000 Factory Building No.1, Zone 1, Zhongtong Glasses Park, Yujiang District, Yingtan City, Jiangxi Province Applicant after: Jiangxi Xingneng Energy Storage Technology Co.,Ltd. Country or region after: China Address before: 5th Floor, Scientific Research Building, Yueyang Modern Equipment Manufacturing Industrial Park, Muli Port, Economic and Technological Development Zone, Yueyang City, Hunan Province 414000 Applicant before: Yueyang yaoning New Energy Technology Co.,Ltd. Country or region before: China |