Battery cluster level optimizer and energy storage system

Abstract

The utility model provides a battery cluster-level optimizer and an energy storage system. The battery cluster-level optimizer comprises a high-voltage box and a cluster-level control unit, the high-voltage box comprises a switch module and a DCDC module; the first end of the switch module is connected with a direct current bus of an energy storage converter in the energy storage system, and the second end of the switch module is connected with a corresponding battery cluster in the energy storage system; a first end of the DCDC module is connected with the DC bus, and a second end of the DCDC module is connected with a corresponding battery cluster in the energy storage system; and the cluster-level control unit is respectively in communication connection with the switch module and the DCDC module, and is used for controlling the switch module to be closed and controlling the DCDC module to be started when the battery cluster needs to be subjected to electric quantity equalization. According to the battery cluster level optimizer, high-power equalization processing can be carried out on all the battery clusters when the electric quantities of the battery clusters are greatly different, so that rapid equalization among the battery clusters is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of energy storage, and in particular to a battery cluster-level optimizer and an energy storage system. Background Art

[0002] A battery cluster is composed of multiple batteries connected in series or in parallel. The purpose of series connection is to increase the battery terminal voltage, and the purpose of parallel connection is to increase the battery capacity. Each battery cluster is connected to an energy storage inverter, which is then connected to the power grid to form an energy storage system. Among them, the battery cluster is a key component for storing and releasing electrical energy, and is a key device of the energy storage system, which directly affects the safe and stable operation of the energy storage system.

[0003] In the later stages of operation of traditional energy storage systems, the consistency differences between battery cells widen. If a single battery cell is over-voltage (triggering charging ban) or under-voltage (triggering discharge ban) in advance, the entire system will shut down, resulting in a decrease in the available capacity of the entire battery compartment. Although the battery cell control unit in the prior art is designed with two methods, active balancing and passive balancing, to address the differences between battery cells, during active balancing, each battery cluster is connected to the energy storage inverter through a DCDC module, and the DCDC module is used to perform charging, discharging and balancing management of the corresponding battery cluster. This method requires that each battery cluster be equipped with a high-power DCDC module to achieve charging and discharging scheduling of the entire battery cluster, so it has high requirements on the specifications of the device. Passive balancing is mainly aimed at the differences between battery cells. The balancing power of this method is too small. After long-term operation of the battery cells, the passive balancing ability between the battery cells cannot make up for the attenuation of the battery cells themselves, resulting in a gradual widening of the consistency differences between the battery cells. Utility Model Content

[0004] The embodiment of the utility model provides a battery cluster level optimizer and an energy storage system to solve the problem of the increasing differences between battery clusters in the prior art.

[0005] In a first aspect, an embodiment of the utility model provides a battery cluster-level optimizer, comprising: a high-voltage box and a cluster-level control unit; the high-voltage box comprises a switch module and a DCDC module;

[0006] The first end of the switch module is connected to the DC bus of the energy storage converter in the energy storage system, and the second end of the switch module is connected to the corresponding battery cluster in the energy storage system;

[0007] A first end of the DCDC module is connected to the DC bus, and a second end of the DCDC module is connected to a corresponding battery cluster in the energy storage system;

[0008] The cluster-level control unit is respectively connected to the switch module and the DCDC module for controlling the switch module to be turned off and the DCDC module to be turned on when the battery cluster needs to be charged.

[0009] In a possible implementation, the DCDC module includes:

[0010] A first capacitor, a second capacitor, a third capacitor, a first inductor, a first switch unit, a second switch unit, a third switch unit and a fourth switch unit;

[0011] The first end of the first inductor is connected to the positive electrode of the first end of the DCDC module, the second end of the first inductor is respectively connected to the first end of the first switch unit, the first end of the third switch unit and the first end of the first capacitor, the second end of the first switch unit is connected to the first end of the second switch unit, the second end of the second switch unit and the second end of the first capacitor are respectively connected to the negative electrode of the DCDC module, the second end of the third switch unit is connected to the first end of the fourth switch unit, and the second end of the fourth switch unit is connected to the positive electrode of the second end of the DCDC module; the first end of the second capacitor is connected to the first end of the second switch unit, and the second end of the second capacitor is connected to the second end of the third switch unit; the third capacitor is connected between the positive and negative electrodes of the output end of the DCDC module.

[0012] In a possible implementation manner, the switch module includes a main contactor; a first end of the main contactor is connected to the DC bus, and a second end of the main contactor is connected to a corresponding battery cluster.

[0013] In a possible implementation manner, the switch module further includes a secondary contactor and a first resistor;

[0014] A first end of the first resistor is connected to the DC bus, a second end of the first resistor is connected to a first end of the auxiliary contactor, and a second end of the auxiliary contactor is connected to a corresponding battery cluster.

[0015] In a possible implementation manner, the high voltage box further includes an isolating switch;

[0016] The first end of the isolating switch is connected to the DC bus, and the second end of the isolating switch is respectively connected to the first end of the switch module and the first end of the DCDC module.

[0017] In a possible implementation, the battery cluster level optimizer further includes a first filtering module;

[0018] The first end of the first filter module is connected to the DC bus, and the second end of the first filter module is connected to the first end of the DCDC module.

[0019] In a possible implementation, the battery cluster level optimizer further includes a second filtering module;

[0020] The first end of the second filter module is connected to the second end of the DCDC module; the second end of the second filter module is connected to the corresponding battery cluster.

[0021] In a second aspect, this embodiment provides an energy storage system, including: a plurality of battery clusters, a battery cluster-level optimizer corresponding to each battery cluster, and an energy storage converter;

[0022] Each battery cluster is connected to the DC bus of the energy storage converter through its corresponding battery cluster-level optimizer.

[0023] In a possible implementation manner, the energy storage system further includes a main control unit;

[0024] The main control unit is respectively connected to the energy storage converter and the cluster-level control units corresponding to each battery cluster in communication;

[0025] The main control unit is used to control the energy storage converter and send a balancing control instruction to the cluster-level control unit;

[0026] The cluster-level control unit controls the corresponding switch module and DCDC module to perform corresponding actions based on the balancing control instruction.

[0027] In a possible implementation, the energy storage system further includes a battery control unit corresponding to each battery in the battery cluster;

[0028] Each battery control unit in the same battery cluster is respectively connected to a cluster-level control unit corresponding to the battery cluster for communication, and is used to send the electrical parameters of the battery to the cluster-level control unit.

[0029] The utility model embodiment provides a battery cluster-level optimizer and energy storage system, the battery cluster-level optimizer includes a high-voltage box and a cluster-level control unit; the high-voltage box includes a switch module and a DCDC module; the first end of the switch module is connected to the DC bus of the energy storage converter in the energy storage system, and the second end of the switch module is connected to the corresponding battery cluster in the energy storage system; the first end of the DCDC module is connected to the DC bus, and the second end of the DCDC module is connected to the corresponding battery cluster in the energy storage system; the cluster-level control unit is respectively connected to the switch module and the DCDC module for communication, and is used to control the switch module to close and the DCDC module to start when the battery cluster needs to be balanced. The above-mentioned cluster-level optimizer can use the DCDC module to perform high-power balancing management on the battery cluster when there is imbalance between battery clusters. Compared with the passive balancing for the differences between battery cells, the cluster-level optimizer provided by the present application can reduce the differences between battery clusters more quickly, thereby improving the efficiency of balancing management. Moreover, the DCDC module provided in the present application only needs to balance the power difference between battery clusters, and does not need to manage the charge and discharge of the battery cluster in the full range. Therefore, the requirements for the maximum power, voltage resistance, and tolerance of the DCDC module are not high, so there is no need to select a very high-power DCDC module, thereby saving device costs and heat dissipation costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0031] Figure 1 A schematic diagram of the structure of the energy storage system provided by the embodiment of the utility model;

[0032] Figure 2 It is a circuit diagram of a DCDC module provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0033] In the following description, specific details such as specific system structures and technologies are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details that hinder the description of the present invention.

[0034] In order to make the purpose, technical solutions and advantages of the utility model clearer, specific embodiments will be described below in conjunction with the accompanying drawings.

[0035] Figure 1 This is a schematic diagram of the structure of the battery cluster level optimizer provided in the embodiment of the utility model. Figure 1 As shown, the battery cluster level optimizer includes:

[0036] A high voltage box and a cluster-level control unit; the high voltage box includes a switch module and a DCDC module;

[0037] The first end of the switch module is connected to the DC bus of the energy storage converter in the energy storage system, and the second end of the switch module is connected to the corresponding battery cluster in the energy storage system;

[0038] A first end of the DCDC module is connected to the DC bus, and a second end of the DCDC module is connected to a corresponding battery cluster in the energy storage system;

[0039] The cluster-level control unit is respectively connected to the switch module and the DCDC module for controlling the switch module to be turned off and the DCDC module to be turned on when the battery cluster needs to be charged.

[0040] In this embodiment, when the battery cluster performs normal charge and discharge tasks, the switch module controls the on and off of the battery cluster. When the battery cluster performs balancing management, the switch module is turned off and the DCDC module is turned on, so that the battery cluster is charged and balanced by the DCDC module.

[0041] Specifically, the cluster-level control unit can control the switch module to turn off and control the DCDC module to start when the user inputs a power balancing instruction. The cluster-level control unit can also communicate with the main control unit of the energy storage system to obtain the balancing control instruction of the main control unit, and control the switch module and the DCDC module to perform corresponding actions based on the balancing control instruction of the main control unit.

[0042] In one possible implementation, Figure 2 As shown, the DCDC module includes:

[0043] A first capacitor C1, a second capacitor C2, a third capacitor C3, a first inductor L1, a first switch unit Q1, a second switch unit Q2, a third switch unit Q3 and a fourth switch unit Q4;

[0044] The first end of the first inductor L1 is connected to the positive electrode of the first end of the DCDC module, the second end of the first inductor L1 is respectively connected to the first end of the first switch unit Q1, the first end of the third switch unit Q3 and the first end of the first capacitor C1, the second end of the first switch unit Q1 is connected to the first end of the second switch unit Q2, the second end of the second switch unit Q2 and the second end of the first capacitor C1 are respectively connected to the negative electrode of the DCDC module, the second end of the third switch unit Q3 is connected to the first end of the fourth switch unit Q4, and the second end of the fourth switch unit Q4 is connected to the positive electrode of the second end of the DCDC module; the first end of the second capacitor C2 is connected to the first end of the second switch unit Q2, and the second end of the second capacitor C2 is connected to the second end of the third switch unit Q3; the third capacitor C3 is connected between the positive and negative electrodes of the output end of the DCDC module.

[0045] Specifically, Figure 2 The circuit structure of the DCDC module given can realize the power grid to balance the power of each battery cluster by charging, so as to improve the balancing efficiency of the battery cluster.

[0046] In one possible implementation, Figure 1 As shown, Figure 1 Taking the first battery cluster as an example, the switch module includes a main contactor KM1-1; a first end of the main contactor KM1-1 is connected to the DC bus, and a second end of the main contactor KM1-1 is connected to the corresponding battery cluster.

[0047] In a possible implementation manner, the switch module further includes a secondary contactor KM1-2 and a first resistor R1;

[0048] The first ends of the first resistors R1 are respectively connected to the DC busbars, the second ends of the first resistors R1 are connected to the first ends of the auxiliary contactors KM1 - 2 , and the second ends of the auxiliary contactors KM1 - 2 are connected to the corresponding battery clusters.

[0049] In a possible implementation, the DCDC module is a bidirectional DCDC circuit. By providing a bidirectional DCDC circuit, charge balancing of an unbalanced battery cluster can be achieved by using a charging or discharging method.

[0050] In a possible implementation manner, the high voltage box further includes an isolating switch QS1;

[0051] The first end of the isolating switch QS1 is connected to the DC bus, and the second end of the isolating switch QS1 is connected to the first end of the switch module and the first end of the DCDC module respectively.

[0052] In a possible implementation manner, a fuse is connected between the battery cluster and the second end of the main contactor.

[0053] In a possible implementation, the battery cluster level optimizer further includes a first filtering module;

[0054] The first end of the first filter module is connected to the DC bus, and the second end of the first filter module is connected to the first end of the DCDC module.

[0055] In a possible implementation, the battery cluster level optimizer further includes a second filtering module;

[0056] The first end of the second filter module is connected to the second end of the DCDC module; the second end of the second filter module is connected to the corresponding battery cluster.

[0057] Specifically, the first filter module is an EMI filter, and the second filter module is an EMI filter.

[0058] In a possible implementation, this embodiment provides an energy storage system, including a plurality of battery clusters, a battery cluster-level optimizer corresponding to each battery cluster, and an energy storage converter;

[0059] Each battery cluster is connected to the DC bus of the energy storage converter through its corresponding battery cluster-level optimizer.

[0060] In a possible implementation manner, the energy storage system further includes a main control unit;

[0061] The main control unit is respectively connected to the energy storage converter and the cluster-level control units corresponding to each battery cluster in communication;

[0062] The main control unit is used to control the energy storage converter and send a balancing control instruction to the cluster-level control unit;

[0063] The cluster-level control unit controls the corresponding switch module and DCDC module to perform corresponding actions based on the balancing control instruction.

[0064] In a possible implementation, the main control unit is connected to each cluster-level control unit via a CAN bus. The main control unit is connected to the energy storage converter via the CAN bus and a dry contact. Each cluster-level control unit is connected to a corresponding DCDC module via a dry contact.

[0065] In a possible implementation, the energy storage system further includes a battery control unit corresponding to each battery in the battery cluster;

[0066] Each battery control unit in the same battery cluster is respectively connected to a cluster-level control unit corresponding to the battery cluster for communication, and is used to send the electrical parameters of the battery to the cluster-level control unit.

[0067] In a possible implementation, the cluster-level control unit is connected to each battery control unit via a CAN bus communication, and each battery control unit is connected to a corresponding battery via a dry contact.

[0068] In one possible implementation, the main control unit is also connected to the dehumidifier, liquid cooling unit and air conditioner of the energy storage system through the RS485 bus, and is connected to the operation light, fault light, fire warning, fire action, UPS, emergency stop feedback, water immersion feedback and door status through dry contacts.

[0069] The above cluster-level optimizer can use the DCDC module to perform high-power balancing management on the battery cluster when there is imbalance between battery clusters. Compared with the passive balancing for the differences between battery cells, the cluster-level optimizer provided by the present application can reduce the differences between battery clusters more quickly, thereby improving the efficiency of balancing management. Moreover, the DCDC module provided by the present application only needs to balance the difference in power between battery clusters, and does not need to manage the charge and discharge of the battery cluster in the full range. Therefore, the maximum power, withstand voltage, and tolerance of the DCDC module are not required to be high, so there is no need to select a very high-power DCDC module, thereby saving device costs and heat dissipation costs.

[0070] The present invention provides a method for managing energy storage battery balance, which is applied to the above energy storage system and is described in detail as follows:

[0071] S101: acquiring electrical parameters of each battery cluster, and determining whether there is a battery cluster with unbalanced charge according to the electrical parameters of each battery cluster.

[0072] In this embodiment, the execution subject of this embodiment may be a controller of the energy storage system. The controller may be a main control unit of the energy storage system, or a separate cluster-level optimization controller. This embodiment takes the main control unit as an example for subsequent explanation.

[0073] Specifically, the electrical parameters include but are not limited to the total voltage of the battery cluster, the battery voltage, the battery cluster SOC (State of Charge), etc., wherein the battery voltage is obtained by the battery control unit and sent to the cluster-level control unit, and the cluster-level control unit obtains the total voltage of the battery cluster based on the battery voltage of each battery in the battery cluster, and sends the total voltage of the battery cluster, the voltage of each battery in the corresponding battery cluster, and the SOC value of the battery cluster to the main control unit. The main control unit determines whether there is a battery cluster with unbalanced power according to the total voltage and / or SOC value of each battery cluster.

[0074] In a possible implementation manner, the electrical parameters include battery voltage and SOC value; the specific implementation process of S101 includes:

[0075] Calculate the difference between the current SOC value of each battery cluster and the SOC reference value to obtain the power deviation value corresponding to each battery cluster; when the battery cluster adopts the charging mode to balance the power, the SOC reference value is the maximum SOC value of all battery clusters in the energy storage system; when the battery cluster adopts the discharging mode to balance the power, the SOC reference value is the minimum SOC value of all battery clusters in the energy storage system;

[0076] If the power deviation value of a battery cluster is greater than a preset deviation threshold, and the battery voltage difference between batteries in the battery cluster exceeds a preset voltage threshold, it is determined that the power of the battery cluster is unbalanced.

[0077] In this embodiment, if there is a battery cluster whose power deviation value is greater than a preset deviation threshold, the difference between the maximum battery voltage and the minimum battery voltage of all batteries in the battery cluster is calculated. If the difference between the maximum battery voltage and the minimum battery voltage of all batteries in the battery cluster exceeds the preset voltage threshold, it is determined that the power of the battery cluster is unbalanced.

[0078] Specifically, using the above method for determining an unbalanced battery cluster based on the maximum SOC value, after determining the unbalanced battery cluster, it is necessary to use a charging method to balance all battery clusters to achieve charge balance for all battery clusters. Wherein, when performing charge balance detection during the charging process, the SOC value of each battery cluster is the maximum SOC value among the SOC values ​​corresponding to each battery in the battery cluster. Using the above method for determining an unbalanced battery cluster based on the minimum SOC value, after determining the unbalanced battery cluster, it is necessary to use a discharging method to balance all battery clusters to achieve charge balance for all battery clusters. When performing charge balance detection during the discharging process, the SOC value of each battery cluster is the minimum SOC value among the SOC values ​​corresponding to each battery in the battery cluster.

[0079] Exemplarily, the power deviation value may be 1% to 10%, preferably, the power deviation value may be 5%. The preset voltage threshold may be 0.1V to 0.6V, preferably, the preset voltage threshold may be 0.35V.

[0080] S102: If there are battery clusters with unbalanced charge, control the switch modules corresponding to the respective battery clusters to disconnect the corresponding battery clusters from the DC bus.

[0081] In this embodiment, when a battery cluster with unbalanced power is detected, a switch module disconnection instruction and a DCDC module start-up instruction are sent to each cluster-level control unit respectively. After receiving the switch module disconnection instruction and the DCDC module start-up instruction, the cluster-level control unit first disconnects the main contactor in the corresponding switch module, and then controls the DCDC module corresponding to the battery cluster to start, so as to realize high-power charging and discharging of the battery cluster through the DCDC module, so as to achieve rapid balancing of the battery cluster.

[0082] In a possible implementation, the specific implementation process of S102 includes:

[0083] If there is a battery cluster with unbalanced power, when it is monitored that the energy storage system triggers a preset prohibition condition, the energy storage converter is prohibited from charging and discharging; the preset prohibition condition includes a prohibition of charging condition and / or a prohibition of discharging condition;

[0084] After receiving the cluster-level balancing confirmation instruction from the user, controlling the energy storage converter and all main contactors to be closed;

[0085] Accordingly, after starting the DCDC modules corresponding to the battery clusters, the method provided in this embodiment further includes:

[0086] The energy storage converter is controlled to start, and the restriction on charging and discharging of the energy storage converter is lifted.

[0087] Specifically, if there are battery clusters with unbalanced charge, the main control unit controls the energy storage inverter to prohibit charging and discharging when the energy storage system is fully charged (triggering a charging prohibition condition) or fully discharged (triggering a discharging prohibition condition), and then the main control unit obtains the remaining available capacity of the energy storage system and generates a battery cluster balancing prompt message. After the user sees the battery cluster balancing prompt message, if he confirms to perform battery cluster balancing, the main control unit generates a cluster-level balancing confirmation instruction, and controls the energy storage inverter to shut down according to the cluster-level balancing confirmation instruction, and sends a switch module shutdown instruction to the cluster-level control units corresponding to each battery cluster. The cluster-level control unit controls the main contactor of the corresponding switch module to disconnect based on the switch module shutdown instruction, so that all battery clusters are disconnected from the energy storage inverter PCS.

[0088] S103: Start the DCDC modules corresponding to each battery cluster, and control the DCDC modules corresponding to each battery cluster to operate at their own balanced power, so that each battery cluster can balance the power through the power grid; the balanced power of each DCDC module is related to the electrical parameters of the corresponding battery cluster.

[0089] In a possible implementation manner, after the prohibition of charging and discharging of the energy storage converter is lifted, the method provided in this embodiment further includes:

[0090] When the battery cluster is charged and the battery is balanced, the energy storage converter is controlled to operate at a first voltage; the first voltage is greater than the target total voltage of the battery cluster;

[0091] When the battery cluster is charged and balanced in a discharging manner, the energy storage converter is controlled to operate at a second voltage, and the second voltage is less than the target total voltage of the battery cluster.

[0092] In this embodiment, when the main control unit sends the switch module closing instruction to each cluster-level control unit, it also sends the DCDC module starting instruction. After the main contactor of the switch module corresponding to each battery cluster is disconnected, the cluster-level control unit controls the corresponding DCDC module to start based on the DCDC module starting instruction, and stops the pulse, so that the DCDC module operates in a constant voltage mode; then, the cluster-level control unit sends the DCDC starting information to the main control unit. After receiving the DCDC starting information, if the battery cluster is charged and the battery cluster is charged, the main control unit adjusts the equalization charging voltage of the energy storage inverter to the first voltage; if the battery cluster is discharged and the battery cluster is charged and the battery cluster is discharged, the discharge voltage of the energy storage inverter is controlled to be adjusted to the second voltage to ensure that there is a pressure difference between the energy storage inverter and the battery cluster during the step-up (charging) or step-down (discharging) process.

[0093] Exemplarily, the difference between the first voltage and the target total voltage of the battery cluster may be 40V to 60V, and the difference between the second voltage and the target total voltage of the battery cluster may also be 40V to 60V. Preferably, the difference may be 50V.

[0094] Specifically, during charging, the target battery cluster total voltage may be the largest battery cluster total voltage among all battery clusters; during discharging, the target battery cluster total voltage may be the smallest battery cluster total voltage among all battery clusters.

[0095] In this embodiment, after determining the operating voltage of the energy storage inverter, the main control unit starts the energy storage inverter and lifts the prohibition on charging and discharging of the energy storage inverter. After lifting the prohibition on charging and discharging of the energy storage inverter, when the battery cluster is charged and the battery cluster is balanced, the energy storage inverter is controlled to operate at a first voltage; when the battery cluster is discharged and the battery cluster is balanced, the energy storage inverter is controlled to operate at a second voltage.

[0096] In a possible implementation manner, the electrical parameter includes an SOC value; the specific implementation process of S103 includes:

[0097] Control the DCDC modules corresponding to each battery cluster to run in parallel;

[0098] During operation, the balancing power of the corresponding DCDC module is determined according to the SOC balancing value of each battery cluster, and the SOC balancing value is positively correlated with the balancing power, and the SOC balancing value is the difference between the current SOC value of the battery cluster and the target SOC value;

[0099] The DCDC modules corresponding to each battery cluster are controlled to operate at the corresponding balanced power.

[0100] Specifically, after the main control unit controls the energy storage converter to start, it sends a DCDC parallel operation instruction to each cluster-level control unit at the same time. Each cluster-level control unit controls the corresponding DCDC module to perform parallel boost operation at the DC bus end according to the parallel operation instruction, and during the operation, determines the balancing power of the corresponding DCDC module according to the SOC to be balanced value of each battery cluster, so as to ensure that the charging and discharging progress of each battery cluster is consistent as much as possible, reduce the balancing end time difference between each battery cluster, and accelerate the progress of the balancing task.

[0101] In a possible implementation manner, the electrical parameter includes an SOC value; after S103, the method provided in this embodiment further includes:

[0102] S201: Determine respectively whether each battery cluster has completed power balancing, and control the DCDC modules corresponding to the battery clusters that have completed power balancing to prohibit charging and discharging.

[0103] S202: Determine whether all battery clusters have completed power balancing. If all battery clusters have completed power balancing, turn off the DCDC modules corresponding to each battery cluster.

[0104] S203: Determine whether the difference between the maximum value of the total voltage of the battery clusters and the minimum value of the total voltage of the battery clusters in all the battery clusters is less than a preset voltage threshold; if the difference between the maximum value of the total voltage of the battery clusters and the minimum value of the total voltage of the battery clusters in all the battery clusters is less than the preset voltage threshold, control each switch module to close the connection between the corresponding battery cluster and the DC bus.

[0105] In this embodiment, the method for determining power balancing includes:

[0106] Determine whether the first battery cluster triggers a preset prohibition condition. If the preset prohibition condition is triggered, determine that the first battery cluster has completed power balancing, wherein the preset prohibition condition includes a prohibition charge condition and / or a prohibition discharge condition; the first battery cluster is any battery cluster of the energy storage system.

[0107] In this embodiment, if charging is used to balance the battery clusters, the grid electrical signal is transmitted to the first battery cluster after passing through the PCS and DCDC modules.

[0108] Specifically, when the cluster-level control unit corresponding to the first battery cluster monitors that the total battery cluster voltage of the first battery cluster reaches the full charge voltage threshold or the SOC value of the first battery cluster reaches the full charge SOC threshold, the charging prohibition condition is triggered, and the DCDC module corresponding to the first battery cluster is controlled to prohibit charging and discharging. The cluster-level control unit sends the charging prohibition condition triggering instruction corresponding to the first battery cluster and the total battery cluster voltage to the main control unit. After monitoring the charging prohibition condition triggering instruction, the main control unit determines that the first battery cluster has completed power balancing.

[0109] In this embodiment, if the battery clusters are charged and balanced by discharging, the first battery cluster is discharged to the grid after passing through the DCDC module and the PCS.

[0110] Specifically, when the cluster-level control unit corresponding to the first battery cluster detects that the total battery cluster voltage of the first battery cluster reaches the full discharge voltage threshold or the SOC value of the first battery cluster reaches the full discharge SOC threshold, the discharge prohibition condition is triggered, and the DCDC module corresponding to the first battery cluster is controlled to prohibit charging and discharging. The cluster-level control unit sends the charge prohibition condition trigger instruction corresponding to the first battery cluster and the total battery cluster voltage to the main control unit. After detecting the charge prohibition condition trigger instruction, the main control unit determines that the first battery cluster has completed power balancing.

[0111] In this embodiment, when it is determined that the first battery cluster has completed power balancing, a DCDC charge and discharge prohibition instruction is sent to the cluster-level control unit corresponding to the first battery cluster. The cluster-level control unit prohibits the corresponding DCDC charging and discharging according to the DCDC charge and discharge prohibition instruction and stops the pulse.

[0112] In a possible implementation, the specific implementation process of S202 includes:

[0113] If all battery clusters trigger the preset prohibition condition, or the difference between the maximum value of the total voltage of the battery cluster and the minimum value of the total voltage of the battery cluster in all battery clusters is less than the preset voltage threshold, it is determined that all battery clusters have completed power balancing;

[0114] The prohibition conditions include prohibition charging conditions and prohibition discharging conditions.

[0115] Specifically, the conditions for determining whether the battery cluster has completed power balancing in this embodiment may include not only full charging and full discharging, but also, during the charging and discharging process, if it is monitored that the difference between the maximum battery cluster total pressure and the minimum battery cluster total pressure in all battery clusters is not greater than the preset voltage difference, it means that the battery cluster total pressures of all battery clusters are close, and it can be determined that all battery clusters have completed power balancing. This method requires precise calculation to determine the timing for completing power balancing, but there is no need to wait until all battery clusters are fully charged / fully discharged before exiting the balancing mode, and scheduling is more flexible.

[0116] Exemplarily, the preset voltage difference may be 0.1V to 3V.

[0117] Specifically, after the main control unit detects that all battery clusters have completed power balancing, it controls the energy storage converter PCS and all DCDC modules to shut down in conjunction. Specifically, the main control unit first controls the energy storage converter PCS to shut down, and then sends the DCDC shutdown command to the cluster-level control units corresponding to all battery clusters. Each cluster-level control unit controls the corresponding DCDC module to shut down according to the DCDC shutdown command. Then, the cluster-level control unit sends the shutdown information of the corresponding DCDC module to the main control unit. After the main control unit detects the shutdown information of the DCDC modules corresponding to all battery clusters, it determines whether the difference between the maximum value of the total voltage of the battery clusters and the minimum value of the total voltage of the battery clusters in all battery clusters is less than the preset voltage threshold. If the difference between the maximum value of the total voltage of the battery clusters and the minimum value of the total voltage of the battery clusters in all battery clusters is less than the preset voltage threshold, a switch module closing command is sent to the cluster-level control units of all battery clusters, and the cluster-level control unit closes the main contactor of the corresponding switch module according to the switch module closing command. After the main contactor is closed, each cluster-level control unit is also used to send the closing information of the switch module to the main control unit. After receiving the closing information of all switch modules, the main control unit adjusts the working voltage of the energy storage inverter to the voltage under normal charging and discharging conditions. The main control unit updates the current available capacity of the energy storage system, and the energy storage system resumes normal operation.

[0118] The above method can achieve high-power balancing management of all cells in each battery cluster at the same time, thereby improving the balancing management efficiency, extending the life of the entire battery compartment, and avoiding the continued increase in differences between battery clusters. In scenarios where there is no scheduling demand for the energy storage system and charging and discharging of the power grid is allowed, battery cluster-level balancing management can be quickly achieved. In addition, the software operation logic between the battery cluster-level optimizer and the energy storage inverter and battery cluster provided by this solution is simple, and does not require excessive adjustments under the existing software program framework. It is easy to implement and is suitable for multiple application scenarios such as power stations on the power generation side, power stations on the grid side, and power stations on the power consumption side.

[0119] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.

Claims

1. A battery cluster level optimizer, characterized in that: include: A high voltage box and a cluster-level control unit; the high voltage box includes a switch module and a DCDC module; The first end of the switch module is connected to the DC bus of the energy storage converter in the energy storage system, and the second end of the switch module is connected to the corresponding battery cluster in the energy storage system; A first end of the DCDC module is connected to the DC bus, and a second end of the DCDC module is connected to a corresponding battery cluster in the energy storage system; The cluster-level control unit is respectively connected to the switch module and the DCDC module for controlling the switch module to be turned off and the DCDC module to be turned on when the battery cluster needs to be charged.

2. The battery cluster level optimizer according to claim 1, characterized in that: The DCDC module comprises: A first capacitor, a second capacitor, a third capacitor, a first inductor, a first switch unit, a second switch unit, a third switch unit and a fourth switch unit; The first end of the first inductor is connected to the positive electrode of the first end of the DCDC module, the second end of the first inductor is respectively connected to the first end of the first switch unit, the first end of the third switch unit and the first end of the first capacitor, the second end of the first switch unit is connected to the first end of the second switch unit, the second end of the second switch unit and the second end of the first capacitor are respectively connected to the negative electrode of the DCDC module, the second end of the third switch unit is connected to the first end of the fourth switch unit, and the second end of the fourth switch unit is connected to the positive electrode of the second end of the DCDC module; the first end of the second capacitor is connected to the first end of the second switch unit, and the second end of the second capacitor is connected to the second end of the third switch unit; the third capacitor is connected between the positive and negative electrodes of the output end of the DCDC module.

3. The battery cluster level optimizer according to claim 1, characterized in that: The switch module comprises a main contactor; a first end of the main contactor is connected to the DC bus, and a second end of the main contactor is connected to a corresponding battery cluster.

4. The battery cluster level optimizer according to claim 3, characterized in that: The switch module also includes a secondary contactor and a first resistor; A first end of the first resistor is connected to the DC bus, a second end of the first resistor is connected to a first end of the auxiliary contactor, and a second end of the auxiliary contactor is connected to a corresponding battery cluster.

5. The battery cluster level optimizer according to claim 3, characterized in that: The high voltage box also includes an isolating switch; The first end of the isolating switch is connected to the DC bus, and the second end of the isolating switch is respectively connected to the first end of the switch module and the first end of the DCDC module.

6. The battery cluster level optimizer according to claim 1, characterized in that: The battery cluster level optimizer also includes a first filtering module; The first end of the first filter module is connected to the DC bus, and the second end of the first filter module is connected to the first end of the DCDC module.

7. The battery cluster level optimizer according to claim 1, characterized in that: The battery cluster level optimizer also includes a second filtering module; The first end of the second filter module is connected to the second end of the DCDC module; the second end of the second filter module is connected to the corresponding battery cluster.

8. An energy storage system, characterized in that: It comprises a plurality of battery clusters, and a battery cluster-level optimizer and an energy storage converter as described in any one of claims 1 to 7 corresponding to each battery cluster; Each battery cluster is connected to the DC bus of the energy storage converter through its corresponding battery cluster-level optimizer.

9. The energy storage system according to claim 8, characterized in that: The energy storage system also includes a main control unit; The main control unit is respectively connected to the energy storage converter and the cluster-level control units corresponding to each battery cluster in communication; The main control unit is used to control the energy storage converter and send a balancing control instruction to the cluster-level control unit; The cluster-level control unit controls the corresponding switch module and DCDC module to perform corresponding actions based on the balancing control instruction.

10. The energy storage system according to claim 8, characterized in that: The energy storage system also includes a battery control unit corresponding to each battery in the battery cluster; Each battery control unit in the same battery cluster is respectively connected to a cluster-level control unit corresponding to the battery cluster for communication, and is used to send the electrical parameters of the battery to the cluster-level control unit.

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