Energy storage system and energy storage battery pack

Abstract

The utility model discloses an energy storage system and an energy storage battery pack. The energy storage system comprises a plurality of parallel battery clusters and an inverter, each battery cluster is connected with a power grid through one inverter; the battery cluster comprises a plurality of battery packs which are connected in series; the battery pack comprises a plurality of battery cells connected in series and a bypass module, the plurality of battery cells connected in series form a battery cell group string, and the positive electrode of the battery cell group string is connected with the output positive end of the battery pack through the bypass module; the negative electrode of the battery cell group string is connected with the output negative end of the battery pack through the bypass module, when the battery pack breaks down, the faulted battery pack can be bypassed, so that circuit isolation is carried out on the faulted battery pack in the battery cluster, charging and discharging of other battery packs in the battery cluster are not affected, and the service life of the battery pack is prolonged. And the charging and discharging operation capability of the energy storage system is greatly improved after the battery core in the battery pack breaks down.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of battery energy storage technology, and in particular to an energy storage system and an energy storage battery pack. Background Art

[0002] Battery energy storage systems have attracted widespread attention from researchers due to their application flexibility, controllability and high energy density.

[0003] Current energy storage systems include string-type inverter solutions, which connect battery clusters directly to the inverter to maximize the discharge capacity of each battery cluster. However, if the current or voltage of a single battery cell within a cluster becomes inconsistent, the entire cluster may become unable to charge or discharge due to the voltage of the individual cell. Utility Model Content

[0004] The utility model provides an energy storage system and an energy storage battery pack, which improve the charging and discharging operation capability of the energy storage system after a cell failure in the battery pack.

[0005] In a first aspect, an embodiment of the present invention provides an energy storage system, comprising: a plurality of parallel-connected battery clusters and inverters;

[0006] Each of the battery clusters is connected to the power grid via an inverter;

[0007] The battery cluster includes a plurality of battery packs connected in series; the battery pack includes a plurality of battery cells connected in series and a bypass module, the plurality of battery cells connected in series form a battery cell string, the positive electrode of the battery cell string is connected to the output positive terminal of the battery pack through the bypass module; the negative electrode of the battery cell string is connected to the output negative terminal of the battery pack through the bypass module; the bypass module is used to open or cut off the path between the output positive terminal of the battery pack and the output negative terminal of the battery pack, and to open or cut off the path between the positive electrode of the battery cell string and the output positive terminal of the battery pack, and between the negative electrode of the battery cell string and the output negative terminal of the battery pack.

[0008] Optionally, the bypass module includes a first switch unit, a second switch unit and a third switch unit;

[0009] The first switch unit is set between the positive pole of the battery cell string and the positive output terminal of the battery pack, the second switch unit is set between the negative pole of the battery cell string and the negative output terminal of the battery pack, and the third switch unit is set between the positive output terminal of the battery pack and the negative output terminal of the battery pack.

[0010] Optionally, the energy storage system further includes a safety unit, and a safety unit is provided between each battery cluster and the inverter.

[0011] Optionally, the insurance unit is a DC fuse.

[0012] Optionally, the total voltage of the battery cluster is within the operating voltage range of the inverter;

[0013] Alternatively, a difference between the total voltage of the battery cluster and an endpoint of an operating voltage range of the inverter is less than or equal to an error threshold.

[0014] Optionally, the operating voltage range of the inverter is 1000~1500V.

[0015] In a second aspect, an embodiment of the present invention provides an energy storage battery pack, which includes a plurality of battery cells connected in series and a bypass module, wherein the plurality of battery cells connected in series form a battery cell string, the positive electrode of the battery cell string is connected to the positive output terminal of the battery pack through the bypass module; the negative electrode of the battery cell string is connected to the negative output terminal of the battery pack through the bypass module; the bypass module is used to open or close the path between the positive output terminal of the battery pack and the negative output terminal of the battery pack, and to open or close the path between the positive electrode of the battery cell string and the positive output terminal of the battery pack, and between the negative electrode of the battery cell string and the negative output terminal of the battery pack.

[0016] The technical solution provided by the embodiment of the present utility model is to set a bypass module in the battery pack so that when the battery pack fails, the faulty battery pack can be bypassed, thereby isolating the circuit of the faulty battery pack in the battery cluster, thereby not affecting the charging and discharging of other battery packs in the battery cluster, and greatly improving the charging and discharging operation capacity of the energy storage system after the battery cell in the battery pack fails. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic structural diagram of an energy storage system provided in an embodiment of the present utility model;

[0018] Figure 2 A schematic structural diagram of a battery pack provided in an embodiment of the present utility model;

[0019] Figure 3 A schematic structural diagram of another battery pack provided in an embodiment of the present utility model. DETAILED DESCRIPTION

[0020] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0021] Currently, energy storage systems can be designed as centralized inverters. These utilize DC-side convergence, ensuring the same operating voltage for each battery cluster. However, if a battery pack experiences inconsistencies, the charge and discharge currents of each cluster differ, resulting in current bias. Consequently, if any one battery cluster discharges completely first, all other clusters must cease discharging. If the charging voltage of any one cluster reaches its upper limit, all other clusters must cease charging, limiting the discharge capacity of the energy storage device.

[0022] Energy storage systems can also be designed as string inverters. This solution directly connects battery clusters to the inverter, resolving imbalances within the container and maximizing the discharge capacity of each battery cluster. However, if current or voltage inconsistencies occur within individual battery packs within a cluster, the entire cluster can become unable to charge or discharge due to the voltage of a single cell, impacting the discharge capacity of each battery cluster.

[0023] In view of this, Figure 1 A schematic diagram of the structure of an energy storage system provided by an embodiment of the present utility model is shown in FIG. Figure 2 A schematic diagram of a battery pack according to an embodiment of the present invention is provided. Figure 1 and Figure 2 , comprising: a plurality of parallel-connected battery clusters 110 and an inverter 120;

[0024] Each battery cluster 110 is connected to the grid via an inverter 120;

[0025] The battery cluster 110 includes a plurality of battery packs 111 connected in series; the battery pack 111 includes a plurality of battery cells 112 connected in series and a bypass module 113, the plurality of battery cells connected in series form a battery cell string, the positive electrode of the battery cell string is connected to the output positive terminal of the battery pack 111 through the bypass module 113; the negative electrode of the battery cell string is connected to the output negative terminal of the battery pack 111 through the bypass module 113; the bypass module 113 is used to open or cut off the path between the output positive terminal of the battery pack 111 and the output negative terminal of the battery pack 111, and to open or cut off the path between the positive electrode of the battery cell string and the output positive terminal of the battery pack 111, and between the negative electrode of the battery cell string and the output negative terminal of the battery pack 111.

[0026] Specifically, the battery cluster 110 comprises a series of battery packs 111, each connected in parallel. Each battery cluster 110 is connected to the power grid via an inverter 120. The total voltage of the series-connected battery clusters 110 must meet the operating voltage range of the inverter 120. For example, when the fully loaded operating voltage of the inverter 120 is 1000-1500V, the entire battery cluster 110 can use M battery packs 111 in series. In this case, the maximum full-charge voltage of the system is 1500V±XV, where the value of X can be determined based on a floating range that meets the application requirements. For example, if a 12V floating voltage is allowed, the maximum full-charge voltage can reach 1512V. The entire battery cluster 110 can use N battery packs 111 in series. In this case, the minimum full-charge voltage of the system can be 1000V±YV, where the value of Y can be determined based on a floating range that meets the application requirements. For example, if a 12V floating voltage is allowed, the minimum full-charge voltage of the system can be 988V. Wherein, M and N are positive integers.

[0027] The battery pack 111 includes battery cells 112 connected in series, which form a battery string. The positive electrode of the battery string is the positive electrode of the first battery cell 112, and the negative electrode of the battery string is the negative electrode of the last battery cell 112. A bypass module 113 is provided between the positive electrode of the battery string and the positive output terminal of the battery pack 111, and between the negative electrode of the battery string and the negative output terminal of the battery pack 111. The bypass module 113 opens or closes the path between the positive output terminal of the battery pack 111 and the negative output terminal of the battery pack 111, between the positive electrode of the battery string and the positive output terminal of the battery pack 111, and between the negative electrode of the battery string and the negative output terminal of the battery pack 111 according to a control signal.

[0028] When it is detected that the voltage of the battery cell 112 in the battery pack 111 is abnormally high or low, the bypass module 113 can open the path between the positive output terminal of the battery pack 111 and the negative output terminal of the battery pack 111 according to the control signal, and cut off the path between the positive electrode of the battery cell string and the positive output terminal of the battery pack 111, and between the negative electrode of the battery cell string and the negative output terminal of the battery pack 111. At this time, the path between the positive output terminal of the battery pack 111 and the negative output terminal of the battery pack 111 is in a bypass state, and the battery cell 112 in the battery pack 111 is isolated by the circuit without affecting the charging and discharging of other battery packs 111 in the battery cluster 110. When the voltage of the battery cells 112 in the battery pack 111 is normal, the bypass module 113 can conduct the path between the positive electrode of the battery cell string and the positive output terminal of the battery pack 111 and between the negative electrode of the battery cell string and the negative output terminal of the battery pack 111 according to the control signal, and cut off the path between the positive output terminal of the battery pack 111 and the negative output terminal of the battery pack 111. At this time, the positive output terminal of the battery pack 111 and the negative output terminal of the battery pack 111 are normally output to the outside. Among them, the control signal received by the bypass module 113 can be generated by the battery management system (Battery Management System, BMS) in the battery pack 111. The BMS can detect the voltage, current and other parameters of the single battery cells 112 in the battery pack 111. When the BMS detects that the voltage of the battery cell 112 is too high or too low, it can generate a corresponding control signal to control the bypass module 113 to perform a corresponding action. When the BMS detects that the parameters of the battery cell 112 are normal, it can generate a corresponding control signal to control the bypass module 113 to perform a corresponding action.

[0029] Because the inverter 120 has a certain operating voltage fluctuation range, some battery packs 111 in each battery cluster 110 can be faulty. However, these faulty battery packs 111 do not affect the charging and discharging process of the entire battery cluster 110. For example, if the fully loaded operating voltage of the inverter 120 is 1000-1500V, and a battery cluster 110 uses 21 battery packs 111 connected in series, the maximum fully charged voltage of the system is 1512V. The minimum voltage is 18 battery packs 111 connected in series, at which point the minimum voltage is 1002V. Therefore, in this battery cluster 110, up to three battery packs 111 can be faulty. The bypass module 113 can isolate the faulty battery packs 111 from the circuit, thus preventing them from affecting the charging and discharging process of the battery cluster 110. It should be noted that the embodiment of the present invention takes the example of allowing a maximum of 3 battery packs 111 to be bypassed. Depending on the operating voltage range of the inverter 120 at full load, the number of battery packs 111 that can be bypassed will also be different. This is only for illustration and does not impose specific restrictions.

[0030] The technical solution provided by the embodiment of the present utility model is to set a bypass module in the battery pack so that when the battery pack fails, the faulty battery pack can be bypassed, thereby isolating the circuit of the faulty battery pack in the battery cluster, thereby not affecting the charging and discharging of other battery packs in the battery cluster, and greatly improving the charging and discharging operation capacity of the energy storage system after the battery cell in the battery pack fails.

[0031] Figure 3 A schematic diagram of another battery pack provided by the present invention is shown in FIG. Figure 3 , the bypass module 113 includes a first switch unit K1, a second switch unit K2 and a third switch unit K3;

[0032] A first switch unit K1 is set between the positive electrode of the battery cell string and the positive output terminal of the battery pack 111, a second switch unit K2 is set between the negative electrode of the battery cell string and the negative output terminal of the battery pack 111, and a third switch unit K3 is set between the positive output terminal of the battery pack 111 and the negative output terminal of the battery pack 111.

[0033] Specifically, the first switch unit K1, the second switch unit K2, and the third switch unit K3 can be relay switches. When the BMS detects that the voltage of the single cell 112 in the battery pack 111 is too high or too low, the BMS sends a control signal to turn off the first switch unit K1 and the second switch unit K2, and turn on the third switch unit K3. At this time, the corresponding battery pack 111 is in a bypass state, achieving circuit isolation of this battery pack 111 without affecting the charging and discharging of other battery packs 111 in the battery cluster 110. When the BMS detects that the voltage of the battery pack 111 is normal, the BMS sends a control signal to turn on the first switch unit K1 and the second switch unit K2, and turn off the third switch unit K3. At this time, the corresponding battery pack 111 is connected in series with the battery cluster 110, and charging and discharging are completed normally in the battery cluster 110.

[0034] Combine Figure 1 and Figure 2In the embodiment of the present invention, the inverter 120 is exemplarily configured with a full-load operating voltage of 1000-1500V, 6 battery clusters 110 are configured, and each battery cluster 110 is configured with 21 battery packs 111. Each battery pack 111 is composed of 21 314A lithium iron phosphate cells 112 connected in series. The maximum full-charge voltage of the system is 1512V. The minimum number of battery packs 111 is 18, and the minimum voltage is 1002V. The total capacity of the energy storage system is 2.5MWh, and a bypass module 113 is provided in each battery pack 111. Therefore, according to the full-load operating voltage range of the inverter 120, 3 battery packs 111 in each battery cluster 110 are allowed to have faults, that is, the entire energy storage system can have a maximum of 18 battery packs 111 in the bypass state without affecting the operation of the entire energy storage system, greatly improving the system's charging and discharging capabilities and its ability to respond to single cell 112 failures.

[0035] Combine Figure 1 In some embodiments, the energy storage system further includes a fuse unit 130, which is provided between each battery cluster 110 and the inverter 120. The fuse unit 130 is a DC fuse. This ensures that if the discharge current of a battery cluster 110 becomes abnormal, the battery cluster 110 can be disconnected immediately without affecting the charging and discharging of other battery clusters 110, thereby improving the operational stability of the energy storage system.

[0036] In some embodiments, the total voltage of the battery cluster 110 connected in series should meet the operating voltage range of the inverter 120. That is, the total voltage of the battery cluster 110 connected in series should be within the operating voltage range of the inverter 120. In other cases, the difference between the total voltage of the battery cluster 110 and the endpoint of the operating voltage range of the inverter 120 is less than or equal to an error threshold. In other words, the total voltage of the battery cluster 110 is allowed to fluctuate somewhat at the endpoint of the operating voltage range of the inverter 120. For example, when the fully loaded operating voltage of the inverter 120 is 1000-1500V, the entire battery cluster 110 can use M battery packs 111 connected in series. In this case, the maximum full-charge voltage of the system is 1500V±XV. Here, the value of X can be determined based on a fluctuation range that meets the application requirements. For example, if a fluctuation of 12V is allowed, the maximum full-charge voltage can reach 1512V. The entire battery cluster 110 can use N battery packs 111 connected in series. In this case, the system's minimum fully charged voltage can be 1000V±YV. Here, the value of Y can be determined based on a floating range that meets the usage requirements. For example, a floating range of 12V is allowed, and the system's minimum fully charged voltage can be 988V. Here, M and N are positive integers. For example, a battery cluster 110 uses 21 battery packs 111 connected in series, and the system's maximum fully charged voltage is 1512V. The minimum is 18 battery packs 111 connected in series, and the minimum voltage is 1002V. Therefore, in this battery cluster 110, a maximum of three battery packs 111 can fail. The bypass module 113 can isolate the failed battery pack 111 from the circuit, so that it does not affect the charging and discharging process of the battery cluster 110. It should be noted that the embodiment of the present invention takes the example of allowing a maximum of 3 battery packs 111 to be bypassed. Depending on the operating voltage range of the inverter 120 at full load, the number of battery packs 111 that can be bypassed will also be different. This is only for illustration and does not impose specific restrictions.

[0037] Combine Figure 2 and Figure 3 The embodiment of the present invention further provides an energy storage battery pack 111, which includes a plurality of battery cells 112 connected in series and a bypass module 113. The plurality of battery cells 112 connected in series form a battery cell string, and the positive electrode of the battery cell string is connected to the positive output terminal of the battery pack 111 through the bypass module 113; the negative electrode of the battery cell string is connected to the negative output terminal of the battery pack 111 through the bypass module 113; the bypass module 113 is used to open or close the path between the positive output terminal of the battery pack 111 and the negative output terminal of the battery pack 111, and to open or close the path between the positive electrode of the battery cell string and the positive output terminal of the battery pack 111, and between the negative electrode of the battery cell string and the negative output terminal of the battery pack 111.

[0038] Specifically, the battery pack 111 includes battery cells 112 connected in series, and the battery cells 112 connected in series form a battery cell string. The positive electrode of the battery cell string is the positive electrode of the first battery cell 112, and the negative electrode of the battery cell string is the negative electrode of the last battery cell 112. A bypass module 113 is provided between the positive electrode of the battery cell string and the positive output terminal of the battery pack 111, and between the negative electrode of the battery cell string and the negative output terminal of the battery pack 111. The bypass module 113 opens or closes the path between the positive output terminal of the battery pack 111 and the negative output terminal of the battery pack 111, between the positive electrode of the battery cell string and the positive output terminal of the battery pack 111, and between the negative electrode of the battery cell string and the negative output terminal of the battery pack 111 according to a control signal.

[0039] When it is detected that the voltage of the battery cell 112 in the battery pack 111 is abnormally high or low, the bypass module 113 can open the path between the positive output terminal of the battery pack 111 and the negative output terminal of the battery pack 111 according to the control signal, and cut off the path between the positive electrode of the battery cell string and the positive output terminal of the battery pack 111, and between the negative electrode of the battery cell string and the negative output terminal of the battery pack 111. At this time, the path between the positive output terminal of the battery pack 111 and the negative output terminal of the battery pack 111 is in a bypass state, and the battery cell 112 in the battery pack 111 is isolated by the circuit without affecting the charging and discharging of other battery packs 111 in the battery cluster 110. When the voltage of the battery cells 112 in the battery pack 111 is normal, the bypass module 113 can conduct the path between the positive electrode of the battery cell string and the positive output terminal of the battery pack 111 and between the negative electrode of the battery cell string and the negative output terminal of the battery pack 111 according to the control signal, and cut off the path between the positive output terminal of the battery pack 111 and the negative output terminal of the battery pack 111. At this time, the positive output terminal of the battery pack 111 and the negative output terminal of the battery pack 111 are normally output to the outside. Among them, the control signal received by the bypass module 113 can be generated by the battery management system (Battery Management System, BMS) in the battery pack 111. The BMS can detect the voltage, current and other parameters of the single battery cells 112 in the battery pack 111. When the BMS detects that the voltage of the battery cell 112 is too high or too low, it can generate a corresponding control signal to control the bypass module 113 to perform a corresponding action. When the BMS detects that the parameters of the battery cell 112 are normal, it can generate a corresponding control signal to control the bypass module 113 to perform a corresponding action.

[0040] Because the inverter 120 has a certain operating voltage fluctuation range, some battery packs 111 in each battery cluster 110 can be faulty. However, these faulty battery packs 111 do not affect the charging and discharging process of the entire battery cluster 110. For example, if the fully loaded operating voltage of the inverter 120 is 1000-1500V, and a battery cluster 110 uses 21 battery packs 111 connected in series, the maximum fully charged voltage of the system is 1512V. The minimum voltage is 18 battery packs 111 connected in series, at which point the minimum voltage is 1002V. Therefore, in this battery cluster 110, up to three battery packs 111 can be faulty. The bypass module 113 can isolate the faulty battery packs 111 from the circuit, thus preventing them from affecting the charging and discharging process of the battery cluster 110. It should be noted that the embodiment of the present invention takes the example of allowing a maximum of 3 battery packs 111 to be bypassed. Depending on the operating voltage range of the inverter 120 at full load, the number of battery packs 111 that can be bypassed will also be different. This is only for illustration and does not impose specific restrictions.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An energy storage system, It is characterized in that include: Multiple parallel battery clusters and inverters; Each of the battery clusters is connected to the power grid via an inverter; The battery cluster includes a plurality of battery packs connected in series; the battery pack includes a plurality of battery cells connected in series and a bypass module, the plurality of battery cells connected in series form a battery cell string, the positive electrode of the battery cell string is connected to the output positive terminal of the battery pack through the bypass module; the negative electrode of the battery cell string is connected to the output negative terminal of the battery pack through the bypass module; the bypass module is used to open or close the path between the output positive terminal of the battery pack and the output negative terminal of the battery pack, and to open or close the path between the positive electrode of the battery cell string and the output positive terminal of the battery pack, and between the negative electrode of the battery cell string and the output negative terminal of the battery pack.

2. The energy storage system according to claim 1, It is characterized in that The bypass module includes a first switch unit, a second switch unit and a third switch unit; The first switch unit is arranged between the positive electrode of the battery cell string and the positive output terminal of the battery pack, the second switch unit is arranged between the negative electrode of the battery cell string and the negative output terminal of the battery pack, and the third switch unit is arranged between the positive output terminal of the battery pack and the negative output terminal of the battery pack.

3. The energy storage system according to claim 1, It is characterized in that It also includes a safety unit, which is arranged between each battery cluster and the inverter.

4. The energy storage system according to claim 3, It is characterized in that The insurance unit is a DC fuse.

5. The energy storage system according to any one of claims 1 to 4, It is characterized in that The total voltage of the battery cluster is within the operating voltage range of the inverter; Or, a difference between the total voltage of the battery cluster and an end point of an operating voltage range of the inverter is less than or equal to an error threshold.

6. The energy storage system according to claim 5, It is characterized in that The operating voltage range of the inverter is 1000-1500V.

7. An energy storage battery pack, It is characterized in that The battery pack includes a plurality of battery cells connected in series and a bypass module, wherein the plurality of battery cells connected in series form a battery cell string, wherein the positive electrode of the battery cell string is connected to the positive output terminal of the battery pack through the bypass module; the negative electrode of the battery cell string is connected to the negative output terminal of the battery pack through the bypass module; the bypass module is used to open or close the path between the positive output terminal of the battery pack and the negative output terminal of the battery pack, and to open or close the path between the positive electrode of the battery cell string and the positive output terminal of the battery pack, and between the negative electrode of the battery cell string and the negative output terminal of the battery pack.

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