CN113612264A - Modular multi-level energy storage battery system - Google Patents
Modular multi-level energy storage battery system Download PDFInfo
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- CN113612264A CN113612264A CN202110682357.2A CN202110682357A CN113612264A CN 113612264 A CN113612264 A CN 113612264A CN 202110682357 A CN202110682357 A CN 202110682357A CN 113612264 A CN113612264 A CN 113612264A
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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
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00302—Overcharge protection
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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
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00304—Overcurrent protection
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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
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00306—Overdischarge protection
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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
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00309—Overheat or overtemperature protection
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- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
The invention belongs to the field of power energy storage, and provides a modular multilevel energy storage battery system which is formed by connecting one battery cluster or a plurality of battery clusters in parallel, wherein the battery cluster is formed by connecting one battery pack or a plurality of battery packs in series, each battery pack comprises a battery pack and a half-bridge module, and a direct current output port of each battery pack is connected with the half-bridge module in parallel. The modular multi-level energy storage battery system can realize refined management and control of the charging and discharging processes of the battery pack connected in series in each battery cluster and the battery clusters connected in parallel.
Description
Technical Field
The invention belongs to the field of power energy storage, and particularly relates to a modular multi-level energy storage battery system which is used for performing fine management on battery packs forming the battery system.
Background
In recent years, the proportion of wind power generation and photovoltaic power generation in power systems is greatly increased, and in order to overcome the problems of intermittency and volatility caused by large-scale new energy power generation and grid connection, power energy storage becomes an indispensable part of future power systems.
The electrochemical energy storage system mainly comprises a battery system, an energy storage converter, a transformer, a battery management system and the like. In order to increase the capacity of the battery system, the battery system generally includes a plurality of battery cells connected in series and parallel to form a battery pack, a plurality of battery packs connected in series to form a battery cluster, and a plurality of battery clusters connected in parallel to form the battery system.
Existing battery systems are typically assembled from thousands of battery cells in series-parallel connection in an electrical topology. The internal generation parameters and the external output characteristics of the battery monomers are required to be highly consistent, and when the parameters of the battery monomers are inconsistent, part of the battery monomers are easily in an overcharged or overdischarged state, so that a series of problems of safety and economic loss are caused.
The disadvantages of the prior conventional technology are:
1. the internal parameters of the battery monomers connected in series and parallel are required to be highly consistent with the external output characteristics, so that the cost of battery manufacturing, battery testing and screening and battery grouping is increased;
2. with the increase of the running time of the energy storage system, the parameters and the output characteristics of the series-parallel battery monomers become inconsistent step by step, and the battery monomers with large parameter deviation have the problem of overcharge or overdischarge, so that the temperature of the battery monomers with inconsistent parameters rises, battery monomers are overheated, battery diaphragms of the battery monomers are possibly melted, the problem of thermal runaway of the battery monomers is possibly caused, the thermal runaway of the battery monomers is further spread to the whole battery system, and a fire disaster is caused;
3. the conventional technology adopts a scheme of simply connecting a plurality of battery monomers in series and parallel, after a single battery monomer fails, a battery pack where the battery monomer is located fails, and possibly a battery cluster where the battery pack is located fails, so that the actual available capacity and the service life of a battery system are reduced;
4. the conventional technology lacks fine management and control on the battery pack, the battery system is balanced only by means of active balancing or passive balancing in the battery management system, and the rated currents of the active balancing and the passive balancing are respectively less than 1% or lower than the rated current of a single battery, so that the balancing effect is poor, and the available capacity and the available service life of the battery are quickly attenuated due to the poor balancing effect of the battery;
5. due to the fact that refined active management and control are not conducted on the battery pack in the conventional technology, batteries with large battery output characteristic difference are difficult to combine together in the conventional battery system technology, and the capacity of the battery system is improved;
6. due to the lack of refined active management and control on the battery pack in the conventional technology and the fast attenuation of the capacity and the service life of the conventional battery system, the battery capacity is seriously over-matched when the battery system adopting the conventional technology is constructed in the initial stage, and the cost of the initial investment of the battery system is increased;
7. due to the lack of refined active management and control on the battery pack in the conventional technology, when the battery pack in the conventional battery system breaks down, the battery pack needs to be checked manually, and the operation and maintenance cost is increased;
8. because conventional technology lacks the initiative management and control that becomes more meticulous to the battery package, conventional battery system when the construction installation, need the state of charge of artifical adjustment battery package when energy storage battery construction installation, has increased energy storage battery system's construction installation cost.
Disclosure of Invention
In order to improve the defects in the prior art, the invention provides a modular multi-level energy storage battery system, which realizes the refined management and control of the battery pack connected in series in each battery cluster and the charging and discharging processes of a plurality of parallel battery clusters, and solves the series of problems of safety, capacity loss, service life attenuation, high primary investment and over-distribution, inconvenience in construction and installation, inconvenience in operation and maintenance and the like caused by the lack of the refined management and control of the battery system.
In order to achieve the above object, the present invention provides a modular multi-level energy storage battery system, which is formed by connecting one battery cluster or a plurality of battery clusters in parallel, wherein the battery cluster is formed by connecting one battery pack or a plurality of battery packs in series, the battery pack includes a battery pack and a half-bridge module, and a dc output port of the battery pack is connected in parallel with the half-bridge module.
Through switching on and switching off of the half-bridge module switching tube, the battery pack can be controlled to be connected to the main circuit of the battery cluster or to exit from the main circuit of the battery cluster, and therefore the battery pack is subjected to refined management and control.
Because each battery pack is provided with the half-bridge module, after the battery packs are connected in series to form a battery cluster, the battery cluster can change the output voltage of the battery cluster by putting or cutting the battery packs in the cluster to realize the charge and discharge management of the battery packs in the cluster, and thus after a plurality of battery clusters are connected in parallel to form a battery system, the battery clusters also have active control capability.
Since each battery cluster can change the output voltage of the battery cluster by changing the switching state of the battery pack in the cluster, the battery system is called a modular multi-level battery system.
The battery system is used for realizing the refined management and control of the battery pack connected in series in each battery cluster and the charging and discharging processes of the plurality of battery clusters connected in parallel, and avoiding the problems of capacity loss, fast capacity attenuation, fast service life attenuation, fire hidden danger and the like caused by the series unbalance of the battery packs and the parallel unbalance of the battery clusters in the battery system.
In the above technical solution, the half-bridge module is formed by connecting an upper switch group and a lower switch group in series, the upper switch group and the lower switch group are formed by connecting switch tubes and corresponding anti-parallel diodes in parallel, a high voltage end of the upper switch group is connected with a high potential end of a battery pack, a low potential end of the upper switch group is connected with a high potential end of the lower switch group, the connection point is recorded as a connection point 1, a low potential end of the lower switch group is connected with a low potential end of the battery pack, the connection point is recorded as a connection point 2, a connection terminal is led out from the connection point 1 and the connection point 2 to form an output terminal of the battery pack, and one or more battery packs are connected in series in sequence through the output terminals to form a battery cluster.
In the above technical solution, the low voltage terminals of the plurality of battery clusters are connected in parallel to the dc negative bus of the battery system, and the high voltage terminal of each battery cluster is connected in series with the isolating switch and then connected to the dc positive bus of the battery system.
In the technical scheme, the low-voltage ends of a plurality of battery clusters are connected in parallel to a direct-current negative bus of the battery system, and the high-voltage end of each battery cluster is connected in series with the reactor and the isolating switch and then connected to a direct-current positive bus of the battery system.
In the technical scheme, for each battery pack, the battery pack is connected into the main current-flowing loop of the battery cluster by turning on the upper switch group and turning off the lower switch group, so that the current flowing through the battery pack flows through the battery cluster, and the battery pack is cut off from the main current-flowing loop of the battery cluster by turning on the lower switch group and turning off the upper switch group, so that the current flowing through the battery pack is zero.
In the technical scheme, all the switch tubes of one battery cluster are turned off, so that the battery cluster is withdrawn from the battery system.
In the technical scheme, the charge state of each battery pack is monitored in the running process of each battery cluster, the charge states of the battery packs are sequenced from high to low, M is the total number of battery packs in one battery cluster, K is the number of the battery packs needing to be put in at the current moment, when a battery system is in a charge state or the battery cluster needs to enter the charge state, K battery packs with the lowest charge state sequence are put in, the rest M-K battery packs with the high charge state sequence are cut off, when the battery system is in a discharge state or the battery cluster needs to enter the discharge state, K battery packs with the high charge state sequence are put in, M-K battery packs with the low charge state sequence are cut off, and the charge states of the battery packs in each battery cluster are ensured to be in a balanced state through the balanced switching strategy.
In the above technical scheme, the half-bridge module of the battery pack is operated in the pulse width modulation mode to continuously regulate and control the output voltage of the battery pack, so that the continuous regulation and control of the direct current output voltage of the battery cluster are formed, the battery cluster can controllably exchange electric quantity with other battery clusters, and the current of the battery cluster is limited.
In the technical scheme, each battery cluster is connected with a redundant battery pack in series, and when the battery pack fails, the battery pack is cut off from the battery cluster by triggering the lower switch tube of the failed battery pack to be conducted for a long time, so that the continuity of a current path of the battery cluster is maintained.
In the technical scheme, when the number of the fault battery packs exceeds the number of the configured redundant battery packs, all switch tubes of the cluster where the fault battery packs are located are locked, and after the current flowing through the battery cluster is zero, the bypass switch of the battery cluster is opened, so that the fault battery cluster is cut off from the battery system.
In the above technical solution, the upper switch set and the lower switch set of the half-bridge module are formed by connecting a plurality of switch tubes and anti-parallel diodes thereof in parallel.
In the above technical solution, the number of the switch tubes and the anti-parallel diodes connected in parallel to the lower switch group is greater than the number of the switch tubes and the anti-parallel diodes connected in parallel to the upper switch group, so as to improve the redundancy and reliability of the lower switch group and prevent the lower switch group from breaking the current path of the battery cluster due to the open circuit of the switch tubes.
In general, compared with the conventional direct series-parallel connection type battery system, the modular multi-level energy storage battery system has the following beneficial effects:
(1) the charging and discharging process of each battery pack and the charging and discharging process of each battery cluster can be controlled through the switching operation of the half-bridge module of each battery pack, and the charging and discharging process of each battery cluster cannot be finely controlled or cannot be finely controlled due to the adoption of a simple series-parallel connection mode in the conventional energy storage battery system;
(2) the battery system provided by the invention can finely manage and control the charging and discharging processes of the battery packs, so that the problems of overcharge and overdischarge of a single battery pack caused by direct series connection of the battery packs in the battery cluster of the conventional energy storage battery system can be avoided, the fire problem caused by overcharge and overdischarge of the single battery pack is further avoided, the problem of integral exit of the battery cluster caused by the failure of the single battery pack in the prior art is also avoided, and the utilization rate of the battery cluster is improved;
(3) the battery system provided by the invention can finely manage the charging and discharging processes of the battery clusters, thereby avoiding the problems of overcharge and overdischarge of a single battery cluster caused by direct parallel connection of a plurality of battery clusters in the prior art, greatly avoiding the problems of overcurrent caused by concentrated charging of the single battery cluster by the plurality of battery clusters or concentrated discharging of the plurality of battery clusters by the single battery cluster, and the problems of temperature rise, thermal runaway of the battery and fire caused by the overcurrent;
(4) on the whole, the battery system provided by the invention can improve the utilization rate of the battery system, prolong the service life of the battery, reduce the capacity loss and the service life reduction of the existing battery system caused by the charging and discharging unbalance, reduce the construction and installation cost of the battery system and the operation and maintenance cost of the battery system, reduce the initial investment cost of the battery system, taking a 100MWh energy storage battery system and a 15-year operation time scale as an example, the conventional technology generally needs to replace the battery system as a whole in 7-8 years, and considering the cost reduction of the battery cost due to the time advance, the total investment of the conventional technology on the battery system is about 1 x 0.75 (1+0.4) =1.05 hundred million, the total investment of the technology provided by the invention on the battery system is about 1 x 0.75 (1+0.2) = 0.7=0.63 hundred million, it can be seen that the cost of the technology provided by the present invention on one investment in the battery system is 60% of the cost of the conventional technology.
Drawings
Fig. 1 is a circuit topology diagram of a conventional energy storage battery system, wherein 21 is the conventional energy storage battery system, 2 is a battery pack, 24 is a battery cluster, 5 is an isolating switch, 10 is a direct current positive bus, and 11 is a direct current negative bus.
Fig. 2 is a schematic circuit topology diagram of a modular multilevel energy storage battery system, wherein 1 is a modular multilevel energy storage battery system, 2 is a battery pack, 3 is a battery pack, 4 is a battery cluster, 5 is an isolating switch, 6 is a reactor, 7 is a half-bridge module, 8 is an upper switch set, 9 is a lower switch set, 10 is a dc positive bus, and 11 is a dc negative bus.
Fig. 3 is a simplified wiring diagram of the modular multilevel energy storage battery system of fig. 2, where 1 is the modular multilevel energy storage battery system, 2 is the battery pack, 3 is the battery pack, 4 is the battery cluster, 5 is the isolation switch, 7 is the upper switch set, 8 is the lower switch set, 9 is the half-bridge module, 10 is the dc positive bus, and 11 is the dc negative bus.
Fig. 4 is a schematic circuit topology diagram of a centralized energy storage system formed by the modular multi-level energy storage batteries, where 1 is the modular multi-level energy storage battery system, 10 is a dc positive bus, 11 is a dc negative bus, 12 is an energy storage converter, 13 is a transformer, 14 is a power grid, and 15 is the centralized energy storage system.
Fig. 5 is an implementation of a battery pack in a modular multilevel energy storage battery, where 2 is a battery pack, 3 is a battery pack, 7 is a half-bridge module, 8 is an upper switch set, 9 is a lower switch set, 17 is a switch tube and its anti-parallel diode, and 16 is a battery cell.
Fig. 6 is another implementation of a battery pack in a modular multilevel energy storage battery, where 2 is a battery pack, 3 is a battery pack, 7 is a half-bridge module, 8 is an upper switch set, 9 is a lower switch set, 17 is a switch tube and its anti-parallel diode, and 16 is a battery cell.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Fig. 1 is a schematic diagram of a topology of a conventional energy storage battery system, and the principle of the topology is that a plurality of battery packs 2 are directly connected in series to form a battery cluster 24, and the plurality of battery clusters 24 are externally connected with an isolating switch 5 and then connected in parallel to form a conventional energy storage battery system 21.
One of the main problems of the conventional energy storage battery system shown in fig. 1 is that each battery cluster 24 is formed by directly connecting a plurality of battery packs 2 in series, and the charging and discharging processes of a single battery pack 2 cannot be independently controlled, and in the charging working condition, after a certain battery pack 2 is fully charged, if the overall voltage of the battery cluster 24 where the battery pack 2 is located is still low, the battery pack 2 is still continuously charged, so that the battery pack 2 is overcharged; in the discharging condition, if a certain battery pack 2 has been discharged to the cut-off voltage, in principle, the discharge should not be continued, but if the overall voltage of the battery cluster 24 where the battery pack 2 is located is still relatively high, the battery cluster 24 will continue to discharge, causing the over-discharge of the battery pack 2 in the battery cluster 24, and the over-charge and over-discharge problems of the battery pack cause the capacity and the service life of the battery pack to be rapidly attenuated, so that other battery packs in the battery cluster 24 are more easily in the over-charge or over-discharge state one by one like a domino, thereby causing the overall capacity and the service life of the battery cluster 24 to be rapidly attenuated.
The second major problem of the conventional energy storage battery system shown in fig. 1 is that a plurality of battery clusters 24 are directly connected in parallel to form an energy storage battery system, and if a certain parallel battery cluster 24 is at a low voltage, all other battery clusters all discharge to the battery cluster 24 at the low voltage, so that the battery cluster 24 at the low voltage is prone to have an overcurrent problem, the overcurrent may cause the temperature of the battery pack 2 of the battery cluster 24 to rise, and in a serious case, the battery pack 2 in the battery cluster 24 at the low voltage may melt the diaphragm of the battery pack 2 due to the temperature rise, and further cause the battery pack to enter a thermal runaway state, thereby causing a fire. Similarly, if the voltage of a certain battery cluster 24 connected in parallel is high, when the entire battery system is in a discharge state, the battery cluster 24 with the high voltage will discharge other battery clusters, and further, an over-current problem occurs, and there is a possibility that the over-current problem may gradually evolve into a fire accident.
In order to solve the problems caused by simply connecting the battery packs in series and in parallel in the conventional battery system shown in fig. 1, fig. 2 shows a modular multilevel energy storage battery system 1, wherein a half-bridge module 7 is connected in parallel to a direct current output port of each battery pack 2, each half-bridge module 7 is formed by connecting an upper switch group 8 and a lower switch group 9 in series, each switch group is formed by connecting a switch tube and an anti-parallel diode thereof in parallel, and the battery packs 2 and the half-bridge modules 7 are connected in parallel to form a battery pack 3;
the low potential end of the upper switch group 8 is connected with the high potential end of the lower switch group 9, the connection point is recorded as connection point 1, the low potential end of the lower switch group 9 is connected with the low potential end of the battery pack 2, the connection point is recorded as connection point 2, and the connection terminal is led out from the connection point 1 and the connection point 2 to form the output terminal of the battery pack 3;
one or more battery packs 3 are connected in series in sequence on the output terminal side thereof to form battery clusters 4, the high-voltage end of each battery cluster 4 is connected in series with a reactor 6 and a disconnector 5 and then connected to a positive dc bus 10 of the energy storage battery system, and the low-voltage end of each battery cluster is connected to a negative dc bus 11, thereby forming the modular multilevel energy storage system 1.
In the modular multilevel energy storage battery system shown in fig. 2, the battery pack 2 can be put into the circuit by turning on the upper switch group 8 and turning off the lower switch group 9, the battery pack 2 can be cut off from the circuit by turning off the upper switch group 8 and turning on the lower switch group 9, so that the battery pack 2 can be controlled to be in the put-in state or the cut-off state by controlling the switching state of the half-bridge module 7, and the charging process and the discharging process of the battery pack 2 are finely controlled.
In the modular multilevel energy storage battery system shown in fig. 2, the battery cluster 4 can be withdrawn from the battery system by turning off all the switch groups 8 and 9 in the battery cluster 4, so that the battery cluster 4 is prevented from further participating in the charging process or the discharging process of the battery system.
In the modular multilevel energy storage battery system 1 shown in fig. 2, the number of battery packs of each battery cluster 4 is counted as M, the number of battery packs that need to be put into at the present moment is counted as K, the state of charge of each battery pack 2 is monitored during the operation of each battery cluster 4, when the battery system 1 is in a charging state or the battery cluster 4 needs to enter the charging state, K battery packs 2 with relatively low state of charge are put into, and the rest M-K battery packs 2 with relatively high state of charge are cut off, so that the K battery packs 2 with relatively low state of charge are charged, and the rest M-K battery packs in the cut-off state are not charged; when the battery system 1 is in a discharging state or the battery cluster 4 needs to enter the discharging state, the K battery packs 2 with relatively high charge states are put in, and the M-K battery packs 2 with relatively low charge states are cut off, so that the K battery packs 2 with relatively high charge states are discharged, the electric quantity of the rest M-K battery packs 2 in the cut-off states is basically maintained unchanged, the charge states of the battery packs 2 in each battery cluster 4 are ensured to be in a balanced state through the balanced switching strategy, and M and K are positive integers and M is not less than K.
In the modular multilevel energy storage battery system 1 shown in fig. 2, when the half-bridge modules 7 of one or more battery packs 3 in the same battery cluster 4 are operated in the pulse width modulation mode, the output voltage of the one or more battery packs 3 can be continuously adjusted, so that the output voltage of the battery cluster 4 where the one or more battery packs 3 are located can be continuously adjusted.
In the initial configuration, each battery cluster 4 in the modular multilevel energy storage battery system 1 shown in fig. 2 may be connected in series with a certain number of redundant battery packs 3, and when one or more battery packs 3 in the battery cluster 4 fail, the lower switch group 9 of the failed battery pack 3 is triggered to be in a continuous conducting state, so that the failed battery pack 3 may be removed from the battery cluster 4, and the current path of the battery cluster 4 is kept smooth, so that the failure of the whole battery cluster 4 due to the failure of one or more battery packs 3 is avoided.
In the modular multilevel energy storage battery system 1 shown in fig. 2, if the number of the faulty battery packs 3 exceeds the number of the configured redundant battery packs, all the switch tubes of the faulty battery cluster 4 are turned off, and after the current flowing through the faulty battery cluster 4 crosses zero, the corresponding isolating switch of the battery cluster 4 is turned on, so that the faulty battery cluster 4 is cut off from the battery system 1.
Fig. 3 shows a simplified wiring of a modular multilevel energy storage battery system 1, the topology of which is substantially identical to that of fig. 2, except that each battery cluster has no external reactor 6 compared to fig. 2.
Fig. 4 shows a centralized energy storage system 15 formed by the modular multilevel energy storage battery system 1 and the energy storage converter 12, etc., where 13 is a transformer and a 14-bit ac power grid, the positive dc bus 10 and the negative dc bus 11 of the modular multilevel energy storage battery system 1 are respectively connected to the positive and negative dc poles of the energy storage converter 12, and the ac output of the energy storage converter 12 is connected to the ac power grid 14 after being connected to the ac transformer 13, so as to form the centralized energy storage system 15.
Fig. 5 shows a specific implementation manner of the battery pack 3, the upper switch set 8 and the lower switch set 9 of the half-bridge module 7 are formed by connecting a plurality of switch tubes and anti-parallel diodes 17 thereof in parallel, and the battery pack 2 is formed by connecting 1 or more battery cells in series and in parallel.
Fig. 6 shows another specific implementation manner of the battery pack 3, the upper switch set 8 and the lower switch set 9 of the half-bridge module 7 are formed by connecting a plurality of switch tubes and anti-parallel diodes 17 thereof in parallel, the battery pack 2 is formed by connecting 1 or more battery cells in series and parallel, the difference from fig. 5 is that the number of the switch tubes and their anti-parallel diodes 17 of the lower switch group 9 in parallel in fig. 6 is greater than the number of the switch tubes and their anti-parallel diodes 17 in parallel in the upper switch group 8, thereby providing redundant switch tubes and anti-parallel diodes 17 for the lower switch group 9, so that when one or more switch tubes and anti-parallel diodes 17 thereof fail, the lower switch group 9 can still be safely triggered to conduct, therefore, the battery pack 3 can flow the current of the battery cluster 4, the current of the battery cluster 4 is ensured to be in a through-flow state, and the whole battery cluster 4 cannot be quitted due to the faults of a single switch tube and the anti-parallel diode 17 thereof.
In summary, the present invention provides a modular multilevel energy storage battery system, each battery pack is connected in parallel with a half-bridge module to form a battery pack, the battery pack can be controlled to be in a put-in state or a cut-off state by the half-bridge module, so as to control the battery pack to be connected into a charge-discharge main loop or cut off from the charge-discharge main loop, so as to control the charge-discharge state of each battery pack, each battery cluster is formed by connecting one or more battery packs in series with a switching control capability, so that each battery cluster is also highly controllable, one or more battery clusters are connected in parallel to form the modular multilevel energy storage battery system, compared with a conventional battery system technology in which one or more battery packs are directly connected in series to form a battery cluster, and one or more battery clusters are directly connected in parallel to form a conventional battery system technology, the technical solution provided by the present invention has the advantages that:
(1) the problem of overcharge or overdischarge of a single battery pack in a battery cluster is avoided, so that the capacity loss and the service life loss of a battery system are reduced;
(2) the problems that after a plurality of battery clusters are connected in parallel, other most battery clusters discharge a few battery clusters or the few battery clusters charge other most battery clusters are solved, so that the few battery clusters are prevented from entering an overcurrent state, and series problems of over-temperature, battery diaphragm melting, battery thermal reaction runaway, battery fire and the like caused by overcurrent of the battery clusters are reduced;
(3) because the attenuation loss of the capacity and the service life of the battery system can be reduced, the over-distribution quantity of the battery system can be reduced by 30 percent or more during initial investment;
(4) because each battery pack and each battery cluster are highly controllable, the technical scheme provided by the invention does not need to manually trip the charge state of the battery pack on station in construction, installation and operation maintenance, thereby reducing the construction, installation and operation and maintenance costs;
(5) overall, the battery system provided by the present invention can improve the utilization rate of the battery system, prolong the service life of the battery, reduce the capacity loss of the existing battery system due to the unbalanced charge and discharge, and reduce the initial investment cost of the battery system, for example, a 100MWh energy storage battery system, a 15 year operation time scale, the conventional technology generally needs to replace the battery system as a whole in 7 th to 8 th years, and considering the cost reduction of the battery cost due to the time progress, the total investment of the conventional technology on the battery system is about 1 × 0.75 (1+0.4) =1.05 billion, the total investment of the technology provided by the present invention on the battery system is about 1 × 0.75 × (1+0.2) = 0.7=0.63, and it is known that the cost of the technology provided by the present invention on one-time investment of the battery system is 60% of the cost of the conventional technology.
Details not described in the present specification belong to the prior art known to those skilled in the art.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the present invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (12)
1. A modular multilevel energy storage battery system, characterized in that: the battery system is formed by connecting one battery cluster or a plurality of battery clusters in parallel, the battery cluster is formed by connecting one battery pack or a plurality of battery packs in series, each battery pack comprises a battery pack and a half-bridge module, and a direct current output port of each battery pack is connected with the half-bridge module in parallel.
2. The modular multilevel energy storage battery system of claim 1, wherein: the half-bridge module is formed by connecting an upper switch group and a lower switch group in series, the upper switch group and the lower switch group are formed by connecting switch tubes and corresponding anti-parallel diodes in parallel, a high-voltage end of the upper switch group is connected with a high-potential end of a battery pack, a low-potential end of the upper switch group is connected with a high-potential end of the lower switch group, the connection point is recorded as a connection point 1, a low-potential end of the lower switch group is connected with a low-potential end of the battery pack, the connection point is recorded as a connection point 2, a connecting terminal is led out from the connection point 1 and the connection point 2 to form an output terminal of the battery pack, and one or more battery packs are sequentially connected in series through the output terminal to form a battery cluster.
3. The modular multilevel energy storage battery system of claim 1, wherein: the low-voltage ends of the plurality of battery clusters are connected in parallel to a direct-current negative bus of the battery system, and the high-voltage end of each battery cluster is connected in series with the isolating switch and then connected to a direct-current positive bus of the battery system.
4. The modular multilevel energy storage battery system of claim 1, wherein: the low-voltage ends of the battery clusters are connected in parallel to a direct-current negative bus of the battery system, and the high-voltage end of each battery cluster is connected in series with the reactor and the isolating switch and then connected to a direct-current positive bus of the battery system.
5. The modular multilevel energy storage battery system of claim 1, wherein: for each battery pack, the battery pack is connected into the main current loop of the battery cluster by switching on the upper switch group and switching off the lower switch group, and the battery pack is cut off from the main current loop of the battery cluster by switching on the lower switch group and switching off the upper switch group.
6. The modular multilevel energy storage battery system of claim 1, wherein: all switching tubes of one battery cluster are turned off to withdraw the battery cluster from the battery system.
7. The modular multilevel energy storage battery system of claim 1, wherein: monitoring the charge state of each battery pack in the running process of each battery cluster, sequencing the charge states of the battery packs from high to low, recording M as the total number of battery packs in one battery cluster, and K as the number of the battery packs needing to be put into the battery system at the current moment, putting K battery packs with the lowest charge state sequencing into the battery system when the battery system is in a charging state or the battery cluster needs to enter the charging state, cutting off the rest M-K battery packs with high charge state sequencing, putting K battery packs with high charge state sequencing into the battery system when the battery system is in a discharging state or the battery cluster needs to enter the discharging state, cutting off M-K battery packs with low charge state sequencing, and ensuring the charge states of the battery packs in each battery cluster to be in a balanced state through the balanced switching strategy.
8. The modular multilevel energy storage battery system of claim 1, wherein: the output voltage of the battery pack is continuously regulated and controlled by enabling a half-bridge module of the battery pack to work in a pulse width modulation mode, and then continuous regulation and control of the direct-current output voltage of the battery pack are formed.
9. The modular multilevel energy storage battery system of claim 1, wherein: each battery cluster is connected with a redundant battery pack in series, when the battery pack fails, the battery pack is cut off from the battery cluster by triggering a lower switch tube of the failed battery pack to conduct for a long time, and the continuity of a current path of the battery cluster is maintained.
10. The modular multilevel energy storage battery system of claim 9, wherein: when the number of the fault battery packs exceeds the number of the configured redundant battery packs, all switch tubes of the cluster where the fault battery packs are located are locked, and after the current flowing through the battery cluster is zero, the bypass switch of the battery cluster is opened, so that the fault battery cluster is cut off from the battery system.
11. The modular multilevel energy storage battery system of claim 2, wherein: and the upper switch group and the lower switch group of the half-bridge module are formed by connecting a plurality of switch tubes and anti-parallel diodes thereof in parallel.
12. The modular multilevel energy storage battery system of claim 11, wherein: the number of the switch tubes and the anti-parallel diodes connected in parallel with the lower switch group is more than that of the switch tubes and the anti-parallel diodes connected in parallel with the upper switch group.
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