Energy storage system off-line equalization control method and related device

Abstract

The application provides an energy storage system offline equalization control method and related device. The method is applied to an energy storage system, wherein a high-voltage box of the energy storage system comprises a switch module and a current conversion module; each battery cluster is connected with a first end of a corresponding switch module and a first end of a current conversion module, a second end of each switch module is connected with a direct current bus; a second end of each current conversion module is connected with a three-phase power distribution end of the energy storage system; based on the above structure, when a battery cluster with unbalanced power is monitored, the energy storage current converter and the high-voltage box corresponding to each battery cluster are controlled to be closed; then the current conversion module corresponding to each battery cluster is started, and the current conversion module corresponding to each battery cluster is controlled to perform power equalization on the corresponding battery cluster with the equalization power of each battery cluster. The above method can perform high-power equalization processing on all battery clusters through the current conversion module when the power among the battery clusters is unbalanced, so as to realize rapid equalization among the battery clusters.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage, in particular to an off-line equalization control method for an energy storage system and a related device. BACKGROUND

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

[0003] In the later stage of the operation of the traditional energy storage system, the consistency difference between the battery cells is expanded, and the premature overvoltage (triggering the prohibition of charging) or undervoltage (triggering the prohibition of discharging) of a single battery cell will cause the whole system to shut down, resulting in a decrease in the available capacity of the whole battery cabin. Although the existing technology has two methods of active equalization and passive equalization for the difference between the battery cells, in the active equalization, each battery cluster manages the charging and discharging of the corresponding battery cluster through a DCDC module. This method requires a high-power DCDC module for each battery cluster to realize the charging and discharging scheduling of the whole battery cluster, so the specification requirement of the device is high. The passive equalization is mainly for the difference between the battery cells. The equalization power of this method is too small, and the passive equalization ability between the battery cells cannot make up for the attenuation of the battery cells after long-term operation, resulting in the gradual expansion of the consistency difference between the battery cells. SUMMARY

[0004] The embodiments of the present application provide an off-line equalization control method for an energy storage system and a related device to solve the problem of the continuous expansion of the difference between the battery clusters in the prior art.

[0005] In a first aspect, the embodiments of the present application provide an off-line equalization control method for an energy storage system, which is applied to the energy storage system. The energy storage system includes a controller, an energy storage converter, a plurality of battery clusters, and a high-voltage box corresponding to each battery cluster. The high-voltage box includes a switch module and a converter module. Each battery cluster is connected to the first end of the corresponding switch module and the first end of the converter module. The second end of each switch module is connected to the energy storage converter through a DC bus. The second end of each converter module is connected to the three-phase power distribution end of the energy storage system.

[0006] The method includes:

[0007] Obtaining the electrical parameters of each battery cluster and determining whether there is an unbalanced battery cluster according to the electrical parameters of each battery cluster.

[0008] If there is an unbalanced battery cluster, the energy storage converter and the switch module corresponding to each battery cluster are controlled to be closed.

[0009] The off-line equalization control device comprises an equalization judgment module, an off-line control module and an equalization management module.

[0010] In a second aspect, an off-line equalization control device for an energy storage system is provided. The energy storage system comprises a controller, an energy storage converter, a plurality of battery clusters, and a high-voltage box corresponding to each battery cluster. The high-voltage box comprises a switch module and a converter module. Each battery cluster is connected to a first end of the corresponding switch module and a first end of the corresponding converter module. The second end of each switch module is connected to the energy storage converter through a DC bus. The second end of each converter module is connected to a three-phase power distribution terminal of the energy storage system.

[0011] The device comprises:

[0012] An equalization judgment module is configured to obtain the electrical parameters of each battery cluster and determine whether there is an unbalanced battery cluster based on the electrical parameters of each battery cluster.

[0013] An off-line control module is configured to control the energy storage converter and the switch module corresponding to each battery cluster to be closed if there is an unbalanced battery cluster.

[0014] An equalization management module is configured to start the converter module corresponding to each battery cluster and control the converter module corresponding to each battery cluster to operate at a respective equalization power, so that each battery cluster performs power equalization through the three-phase power distribution terminal. The equalization power of each converter module is related to the electrical parameters of the corresponding battery cluster.

[0015] In a third aspect, a controller is provided. The controller comprises a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the method according to any possible implementation manner of the first aspect are implemented.

[0016] In a fourth aspect, a computer readable storage medium is provided. The computer readable storage medium stores a computer program. When the computer program is executed by a processor, the steps of the method according to any possible implementation manner of the first aspect are implemented.

[0017] In a fifth aspect, an energy storage system is provided. The energy storage system comprises the controller according to the third aspect.

[0018] The embodiment of the present application provides a kind of energy storage system offline equalization control method and related device, which is applied to energy storage system, each battery cluster in the energy storage system is connected with the first end of corresponding switch module and the first end of current conversion module, the second end of each switch module is connected with the energy storage converter through direct current bus;The second end of each current conversion module is connected with three-phase power distribution end;Based on the above structure, when the battery cluster of the present application is monitored to be unbalanced, the energy storage converter and the switch module corresponding to each battery cluster are controlled to be closed;Start the current conversion module corresponding to each battery cluster, and control the current conversion module corresponding to each battery cluster to be balanced with the power of corresponding battery cluster respectively.The above method can use current conversion module to carry out large power equalization management to battery cluster when the battery cluster is unbalanced, compared with passive equalization for the difference between battery cell, the method provided by the present application can reduce the difference between battery cluster faster, thereby improving the equalization management efficiency.Moreover, the current conversion module provided by the present application only needs to equalize the difference in power between battery clusters, and does not need to carry out complete range charge-discharge management of battery cluster, so the maximum power, voltage resistance, tolerance of current module are not high, so it is not necessary to select a large power current conversion module, thereby saving device cost and heat dissipation cost. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 is the application scenario diagram of the structure of the energy storage system provided by the embodiment of the present application;

[0021] Figure 2 is the circuit schematic diagram of the current conversion module provided by the embodiment of the present application;

[0022] Figure 3 is the implementation flowchart of the energy storage system offline equalization control method provided by the embodiment of the present application;

[0023] Figure 4 is the structure schematic diagram of the energy storage system offline equalization control device provided by the embodiment of the present application;

[0024] Figure 5 is the schematic diagram of the controller provided by the embodiment of the present application. DETAILED DESCRIPTION

[0025] In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular architectures, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods, devices, circuits, and

[0026] In order to make the objects, technical solutions and advantages of the present application clearer, the following will be described by specific embodiments in conjunction with the accompanying drawings.

[0027] Figure 1 A structural schematic diagram of an energy storage system according to an embodiment of the present application is shown in FIG. 1. As shown in FIG. 1, the energy storage system includes a controller, a power conversion system (PCS), a plurality of battery clusters, and a high-voltage box corresponding to each battery cluster; the high-voltage box includes a switching module and an AC / DC conversion module. Figure 1

[0028] Each battery cluster is connected to a first end of the corresponding switching module and a first end of the AC / DC conversion module, a second end of each switching module is connected to the PCS through a DC bus, and a second end of each AC / DC conversion module is connected to a three-phase power distribution end of the energy storage system.

[0029] Specifically, when the battery cluster is performing a normal charging and discharging task, the switching module controls the on and off of the battery cluster, when the battery cluster is performing equalization management, the switching module is off and the AC / DC conversion module is on, so that the battery cluster is equalized in electric quantity through the three-phase power distribution end.

[0030] Specifically, the AC / DC conversion module is used to rectify the alternating current of the three-phase power distribution end into direct current and transmit it to the battery cluster, or convert the direct current of the battery cluster into alternating current and transmit it to the three-phase power distribution end. The three-phase power distribution end can be a station power distribution end, which is connected to the power grid through a transformer. In addition, the three-phase power distribution end can also be other external three-phase power supply ends.

[0031] In one possible implementation, as shown in FIG. 2, the AC / DC conversion module includes a rectification unit 101 and a DC / DC unit 103. Figure 2

[0032] The alternating current end of the rectification unit 101 is connected to the three-phase power distribution end, the direct current end of the rectification unit 101 is connected to a first end of the DC / DC unit 103, and a second end of the DC / DC unit 103 is connected to the corresponding battery cluster.

[0033] ​​In a possible implementation, the rectifier unit 101 includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, and a sixth diode D6.

[0034] The negative poles of the first diode D1, the second diode D2, and the third diode D3 are respectively connected to the positive pole of the DC end of the rectifier unit; the positive pole of the first diode D1 is respectively connected to the A phase of the three-phase power supply end, and the negative pole of the fourth diode D4; the positive pole of the second diode D2 is respectively connected to the B phase of the three-phase power supply end, and the negative pole of the fifth diode D5; the positive pole of the third diode D3 is respectively connected to the C phase of the three-phase power supply end, and the negative pole of the sixth diode D6; the positive poles of the fourth diode D4, the fifth diode D5, and the sixth diode D6 are respectively connected to the negative pole of the DC end of the rectifier unit.

[0035] In a possible implementation, as shown in Figure 2 The DCDC unit 103 includes a first capacitor C2, a second capacitor C4, 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.

[0036] The first end of the first inductor L1 is connected to the positive pole of the first end of the DCDC unit, 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 C2, 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 C2 are respectively connected to the negative pole of the DCDC unit, 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 pole of the second end of the DCDC unit; the first end of the second capacitor C4 is connected to the first end of the second switch unit Q2, and the second end of the second capacitor C4 is connected to the second end of the third switch unit Q3.

[0037] Specifically, Figure 2 The current conversion module shown in the figure can realize the function of charging the battery cluster from the three-phase power supply end, so that the battery cluster can realize cluster-level power balance in a charging mode.

[0038] In a possible implementation, the current conversion module further includes a buffer unit 102.

[0039] The buffer unit 102 includes a first switch, a seventh diode D7, a second resistor R2, a buffer switch K_f, and a fuse fu.

[0040] The first end of the first switch is connected with the direct current positive pole of the rectifier unit and the anode of the seventh diode D7 respectively, the cathode of the seventh diode D7 is connected with the first end of the buffer switch K_f, the second end of the buffer switch K_f is connected with the first end of the second resistor R2, the second end of the second resistor R2 is connected with the first end of the fuse fu, and the second end of the first switch is connected with the second end of the fuse fu and the first end positive pole of the DCDC unit respectively.

[0041] In a possible implementation, the rectifier unit is a bidirectional synchronous rectifier circuit, and correspondingly, the DCDC unit is a bidirectional DCDC circuit. By arranging the bidirectional synchronous rectifier circuit and the bidirectional DCDC circuit, the power balance of the unbalanced battery cluster can be achieved in the mode of charging the battery cluster from the three-phase power supply end or discharging the three-phase power supply end from the battery cluster.

[0042] In a possible implementation, the current conversion module further comprises a first filter unit.

[0043] The first end of the first filter unit is connected with the direct current end of the rectifier unit, and the second end of the first filter module is connected with the first end of the DCDC unit.

[0044] Specifically, the first filter unit is an EMI filter.

[0045] In a possible implementation, the current conversion module further comprises a second filter unit.

[0046] The first end of the second filter unit is connected with the second end of the DCDC unit, and the second end of the second filter module is connected with the corresponding battery cluster.

[0047] Specifically, the second filter unit is an EMI filter.

[0048] In a possible implementation, the current conversion module comprises a full-control rectifier circuit, which is used to realize the conversion between the alternating current of the three-phase power supply end and the direct current output by the battery cluster.

[0049] In a possible implementation, the switch module comprises a main contactor, the first end of the main contactor is connected with the battery cluster, and the second end of the main contactor is connected with the direct current bus.

[0050] The controller is specifically used to control the main contactor of the switch module corresponding to the battery cluster to be disconnected when it is monitored that there is a battery cluster with unbalanced power.

[0051] Specifically, as shown in Figure 1As shown, the high-voltage box A11 includes a main contactor KM1-1, an auxiliary contactor KM1-3, a disconnector QS1, a first resistor R1 and a current conversion module ACDC1; and the first ends of the main contactor KM1-1 and the auxiliary contactor KM1-3 and the first end of the current conversion module ACDC1 are connected with the corresponding battery cluster, the second end of the auxiliary contactor KM1-3 is connected with the first end of the first resistor R1, the second end of the first resistor R1 and the second end of the main contactor KM1-1 are connected with one end of the disconnector QS1, and the other end of the disconnector QS1 is connected with the DC bus; and the second end of the current conversion module ACDC1 is connected with the three-phase power distribution end.

[0052] In one possible implementation, the controller includes a main control unit, a cluster-level control unit corresponding to each battery cluster and a battery control unit corresponding to each battery in the battery cluster;

[0053] The main control unit is in communication connection with the energy storage current converter and each cluster-level control unit, the cluster-level control unit is in communication connection with the switch module, the current conversion module of the corresponding battery cluster and the battery control unit of each battery in the battery cluster, and the battery control unit is in communication connection with the corresponding battery.

[0054] In one possible implementation, the main control unit is in communication connection with each cluster-level control unit through a CAN bus. The main control unit is connected with the energy storage current converter through the CAN bus and dry contact respectively. Each cluster-level control unit is connected with the corresponding current conversion module through dry contact respectively.

[0055] In one possible implementation, the cluster-level control unit is in communication connection with each battery control unit through a CAN bus. Each battery control unit is connected with the corresponding battery through dry contact respectively.

[0056] In one possible implementation, the main control unit is also in communication connection with the dehumidifier, the liquid cooling unit and the air conditioner of the energy storage system through an RS485 bus respectively, and is in communication connection with the operation lamp, the fault lamp, the fire warning, the fire action, the UPS, the emergency stop feedback, the water immersion feedback and the door state through dry contact.

[0057] The above energy storage system can perform offline high-power power balance on all battery clusters when the imbalance occurs between the battery clusters, thereby accelerating the cluster-level balancing efficiency of the energy storage system, avoiding the increase of the difference between the battery clusters and ensuring the safe and efficient charging and discharging work of the energy storage system.

[0058] Referring to Figure 2 which shows the implementation flowchart of the offline balancing control method of the energy storage system provided by the embodiment of the present application, and the details are as follows:

[0059] S101: Obtain the electrical parameters of each battery cluster, and determine whether there is a battery cluster with unbalanced power based on the electrical parameters of each battery cluster.

[0060] In this embodiment, the execution subject of the embodiment can be a controller of the energy storage system. The controller can be a main control unit of the energy storage system, or a separate cluster-level optimization controller. The embodiment takes the main control unit as an example for subsequent explanation and description.

[0061] Specifically, the electrical parameters include, but are not limited to, the total voltage of the battery cluster, the battery voltage, the SOC (State of Charge) of the battery cluster, etc. The battery voltage is obtained by the battery control unit and sent to the cluster-level control unit. 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 battery 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 based on the total voltage of each battery cluster and / or the SOC value.

[0062] In one possible implementation, the electrical parameters include the battery voltage and the SOC value; and the specific implementation process of S101 includes:

[0063] 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 uses charging 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 uses discharging to balance the power, the SOC reference value is the minimum SOC value of all battery clusters in the energy storage system.

[0064] If the power deviation value of a battery cluster is greater than a preset deviation threshold, and the battery voltage difference between the batteries in the battery cluster exceeds a preset voltage threshold, it is determined that the power of the battery cluster is unbalanced.

[0065] In this embodiment, if the power deviation value of a battery cluster 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 a preset voltage threshold, it is determined that the power of the battery cluster is unbalanced.

[0066] Specifically, after the unbalanced battery cluster is determined by the method of determining the unbalanced battery cluster based on the maximum SOC value, the charging mode is used to perform the equalization management on all the battery clusters to realize the equalization of the electric quantity of all the battery clusters. During the equalization detection in the charging process, the SOC value of each battery cluster is the maximum SOC value in the corresponding SOC values of each battery in the battery cluster. After the unbalanced battery cluster is determined by the method of determining the unbalanced battery cluster based on the minimum SOC value, the discharging mode is used to perform the equalization management on all the battery clusters to realize the equalization of the electric quantity of all the battery clusters. During the equalization detection in the discharging process, the SOC value of each battery cluster is the minimum SOC value in the corresponding SOC values of each battery in the battery cluster.

[0067] For example, the electric quantity deviation value can be 1% to 10%, and preferably, the electric quantity deviation value can be 5%. The preset voltage threshold value can be 0.1V to 0.6V, and preferably, the preset voltage threshold value can be 0.35V.

[0068] S102: If there is an electric quantity unbalanced battery cluster, the energy storage converter and the corresponding switch module of each battery cluster are controlled to be closed.

[0069] In this embodiment, when the electric quantity unbalanced battery cluster is monitored, the energy storage converter is controlled to be shut down, and the switch module disconnection instruction and the converter module start instruction are sent to each cluster level control unit. After the cluster level control unit receives the switch module disconnection instruction and the converter module start instruction, the main contactor in the corresponding switch module is disconnected first, and then the converter module corresponding to the battery cluster is controlled to start. The high-power charging or discharging equalization of the battery cluster is realized through the converter module to realize the rapid equalization of the battery cluster.

[0070] In one possible implementation, the specific implementation process of S102 includes:

[0071] If there is an electric quantity unbalanced battery cluster, when the preset prohibition condition of the energy storage system is monitored, the energy storage converter is prohibited to charge and discharge; the preset prohibition condition includes the charge prohibition condition and / or the discharge prohibition condition.

[0072] After receiving the cluster level equalization confirmation instruction of the user, the energy storage converter and all the main contactors are controlled to be closed.

[0073] Specifically, if there is a battery cluster with unbalanced power, the main control unit controls the energy storage converter to prohibit charging and discharging when the energy storage system is full of charge (triggering the prohibition of charging condition) or full of discharge (triggering the prohibition of discharging condition), then the main control unit obtains the remaining available capacity of the energy storage system, and generates a battery cluster balancing prompt information, after the user sees the battery cluster balancing prompt information, if the user confirms to perform battery cluster balancing, the main control unit generates a cluster-level balancing confirmation instruction, and controls the energy storage converter to be closed according to the cluster-level balancing confirmation instruction, and sends a switch module closing instruction to the cluster-level control unit corresponding to each battery cluster, and the cluster-level control unit controls the main contactor of the corresponding switch module to be disconnected based on the switch module closing instruction, so that all battery clusters are disconnected from the energy storage converter PCS.

[0074] S103: Start the conversion module corresponding to each battery cluster, and control the conversion module corresponding to each battery cluster to operate at a respective balancing power, so that each battery cluster performs power balancing through the three-phase power distribution end; the balancing power of each conversion module is related to the electrical parameter of the corresponding battery cluster.

[0075] The above energy storage system can use the conversion module to perform large-power balancing management on the battery clusters when the battery clusters are unbalanced. Compared with passive balancing for differences between battery cells, the method provided in the application can reduce the differences between battery clusters more quickly, thereby improving the balancing management efficiency. Moreover, the conversion module provided in the application only needs to balance the power difference between battery clusters, and does not need to perform charging and discharging management of the entire range of battery clusters, so the requirements for the maximum power, voltage resistance and tolerance of the current module are not high, and therefore a large-power conversion module does not need to be selected, thereby saving the cost of devices and the cost of heat dissipation.

[0076] In one possible implementation, the electrical parameter includes an SOC value; and the specific implementation process of S103 includes:

[0077] According to the SOC value to be balanced of each battery cluster, the balancing power of the corresponding conversion module is determined, and the SOC value to be balanced is positively correlated with the balancing power, and the SOC value to be balanced is the difference between the current SOC value and the target SOC value of the battery cluster;

[0078] The conversion module corresponding to each battery cluster is controlled to operate at the corresponding balancing power.

[0079] The target SOC value is an SOC value at which the battery cluster completes power balancing, which can be a full-charge SOC value, a full-discharge SOC value, or any SOC value other than the full-charge and full-discharge SOC values.

[0080] Specifically, after the switch module corresponding to each battery cluster is closed, the cluster-level control unit sends the switch module closing information to the main control unit. After the main control unit monitors the closing information of the switch module corresponding to all battery clusters, the main control unit sends a start instruction of the current conversion module to the cluster-level control unit of each battery cluster. The cluster-level control unit controls the start of the corresponding current conversion module according to the start instruction of the current conversion module, and runs in the constant voltage mode. During the running process, the main control unit / the cluster-level control unit of each battery cluster determines the equalization power of the corresponding current conversion module according to the SOC value to be balanced of the corresponding battery cluster, so as to control the current conversion module to work based on the equalization power, to ensure the charging and discharging progress of each battery cluster as much as possible, to reduce the difference in the equalization end time between each battery cluster, and to accelerate the process of the equalization task.

[0081] In one possible implementation, the electrical parameter includes an SOC value; after S103, the method provided in this embodiment further includes:

[0082] S201: respectively judging whether each battery cluster completes the equalization of the electric quantity, and controlling the current conversion module corresponding to the battery cluster that completes the equalization of the electric quantity to be prohibited from charging and discharging.

[0083] S202: judging whether all battery clusters complete the equalization of the electric quantity, and if all battery clusters complete the equalization of the electric quantity, closing the current conversion module corresponding to each battery cluster.

[0084] S203: judging whether 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 a preset voltage threshold, and if 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, controlling each switch module to close the connection of the corresponding battery cluster to the DC bus;

[0085] S204: controlling the energy storage current converter to start.

[0086] In the embodiment, each cluster-level control unit respectively judges whether the corresponding battery cluster completes the power balance, if the power balance is completed, the cluster-level control unit controls the corresponding current conversion module to prohibit charging and discharging, the current conversion module stops pulsing, the cluster-level control unit sends the balance completion information to the main control unit, the main control unit determines that all battery clusters have completed the power balance after monitoring the balance completion information of all battery clusters, then issues the current conversion module closing instruction to the cluster-level control unit of each battery cluster, the cluster-level control unit closes the current conversion module according to the current conversion module closing instruction, and uploads the current conversion module closing information to the main control unit, the main control unit judges whether 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 after monitoring the current conversion module closing information of all battery clusters, if 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, the main contactor of each switch module is controlled to be closed, so that each battery cluster is connected to the energy storage current transformer PCS, and finally, when the main control unit monitors that the main contactor of the switch module of each battery cluster is closed, the energy storage current transformer is controlled to start, the main control unit updates the available capacity of the energy storage system, and the energy storage system resumes operation.

[0087] In the embodiment, the method for judging the power balance comprises:

[0088] The first battery cluster is judged whether a preset prohibition condition is triggered, if the preset prohibition condition is triggered, it is determined that the first battery cluster has completed the power balance, wherein the preset prohibition condition comprises a charging prohibition condition and / or a discharging prohibition condition, and the first battery cluster is any battery cluster of the energy storage system.

[0089] In the embodiment, if the charging method is used to balance the power of the battery cluster, the electrical signal of the three-phase power distribution end is transmitted to the first battery cluster through the current conversion module.

[0090] Specifically, when the cluster-level control unit corresponding to the first battery cluster monitors that the total voltage of the battery cluster of the first battery cluster reaches the full charging voltage threshold or the SOC value of the first battery cluster reaches the full charging SOC threshold, the charging prohibition condition is triggered, and the cluster-level control unit controls the current conversion module corresponding to the first battery cluster to prohibit charging and discharging. The cluster-level control unit sends the charging prohibition condition triggering instruction and the total voltage of the battery cluster corresponding to the first battery cluster to the main control unit, and the main control unit determines that the first battery cluster has completed the power balance after monitoring the charging prohibition condition triggering instruction.

[0091] In the embodiment, if the discharging method is used to balance the power of the battery cluster, the first battery cluster is discharged to the three-phase power distribution end through the current conversion module.

[0092] Specifically, when the cluster-level control unit corresponding to the first battery cluster monitors that the total 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 cluster-level control unit triggers the discharging prohibition condition and controls the current conversion module corresponding to the first battery cluster to prohibit charging and discharging. The cluster-level control unit sends the discharging prohibition condition triggering instruction and the total voltage of the first battery cluster to the main control unit, and the main control unit determines that the first battery cluster has completed the power balance after monitoring the discharging prohibition condition triggering instruction.

[0093] In the embodiment, when it is determined that the first battery cluster completes the power balance, the cluster-level control unit corresponding to the first battery cluster is sent the current conversion module charging and discharging prohibition instruction, and the cluster-level control unit prohibits charging and discharging of the corresponding current conversion module according to the current conversion module charging and discharging prohibition instruction and stops the pulse.

[0094] In one possible implementation, the specific implementation process of S202 includes:

[0095] If all the battery clusters trigger the preset prohibition condition, or the difference between the maximum total voltage of the battery clusters and the minimum total voltage of the battery clusters is less than the preset voltage threshold, it is determined that all the battery clusters have completed the power balance.

[0096] The preset prohibition condition includes a charging prohibition condition and / or a discharging prohibition condition.

[0097] Specifically, the condition for determining that the battery cluster completes the power balance in the embodiment can include full charging and full discharging. In the charging and discharging process, if it is monitored that the difference between the maximum total voltage of the battery clusters and the minimum total voltage of the battery clusters is not greater than the preset voltage difference, it is indicated that the total voltages of all the battery clusters are close, and it is determined that all the battery clusters have completed the power balance. This method needs to be accurately calculated to determine the timing of completing the power balance, but does not need to wait for all the battery clusters to be fully charged / fully discharged before exiting the balance mode, and the scheduling is more flexible.

[0098] For example, the preset voltage difference can be 0.1V to 3V.

[0099] The above method can realize simultaneous large-power balance management of all the battery cells of each battery cluster, thereby improving the balance management efficiency, prolonging the service life of the entire battery compartment, avoiding the increase of the difference between the battery clusters, and enabling fast battery cluster-level balance management in a scenario where the energy storage system is not allowed to charge and discharge the power grid. In addition, the software running logic between the battery cluster-level optimizer provided in the scheme and the energy storage current converter and the battery cluster is simple, and no excessive adjustment is needed in the existing software program framework, which is easy to implement and suitable for multiple application scenarios such as power generation side power stations, power grid side power stations, and power consumption side power stations.

[0100] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiment of the application.

[0101] The following is an apparatus embodiment of the application. For details not described in detail, reference can be made to the corresponding method embodiments described above.

[0102] Figure 4 A structural schematic diagram of the off-line equalization control device of the energy storage system provided by the embodiment of the application is shown. For ease of illustration, only the parts related to the embodiment of the application are shown, and the details are as follows:

[0103] As shown in Figure 4 , the off-line equalization control device 100 of the energy storage system comprises:

[0104] The electric quantity equalization judgment module 110 is configured to acquire the electric parameters of each battery cluster and determine whether there is an electric quantity unbalanced battery cluster according to the electric parameters of each battery cluster.

[0105] The off-line control module 120 is configured to control the energy storage converter and the switch module corresponding to each battery cluster to be closed if there is an electric quantity unbalanced battery cluster.

[0106] The equalization management module 130 is configured to start the converter module corresponding to each battery cluster and control the converter module corresponding to each battery cluster to operate at a respective equalization power, so that each battery cluster performs electric quantity equalization through the three-phase power distribution end. The equalization power of each converter module is related to the electric parameters of the corresponding battery cluster.

[0107] In one possible implementation, the electric parameters include battery voltage and SOC value; and the electric quantity equalization judgment module 110 comprises:

[0108] The difference between the current SOC value and the SOC reference value of each battery cluster is calculated to obtain the electric quantity deviation value corresponding to each battery cluster. When the battery cluster performs electric quantity equalization in the charging mode, the SOC reference value is the maximum SOC value of all battery clusters in the energy storage system. When the battery cluster performs electric quantity equalization in the discharging mode, the SOC reference value is the minimum SOC value of all battery clusters in the energy storage system.

[0109] If the electric quantity deviation value of a battery cluster is greater than a preset deviation threshold value, and the battery voltage difference between the batteries in the battery cluster exceeds a preset voltage threshold value, it is determined that the electric quantity of the battery cluster is unbalanced.

[0110] In a possible implementation, the energy storage system further comprises an energy storage converter; a direct-current end of the energy storage converter is connected with the direct-current bus, and an alternating-current end of the energy storage converter is connected with the power grid; the switch module comprises a main contactor, one end of the main contactor is connected with the direct-current bus, and the other end of the main contactor is connected with the corresponding battery cluster.

[0111] The off-line control module 120 comprises:

[0112] If there is a battery cluster with unbalanced power, when it is monitored that the energy storage system triggers a preset inhibition condition, the energy storage converter is inhibited from charging and discharging; the preset inhibition condition comprises a charging inhibition condition and a discharging inhibition condition.

[0113] After receiving a cluster-level balancing confirmation instruction of the user, the energy storage converter and all the main contactors are controlled to be closed.

[0114] In a possible implementation, the electrical parameter comprises an SOC value; the balancing management module 130 comprises:

[0115] According to the SOC value to be balanced of each battery cluster, the balancing power of the corresponding converter module is determined, and the SOC value to be balanced is positively correlated with the balancing power; the SOC value to be balanced is a difference between a current SOC value and a target SOC value of the battery cluster.

[0116] The converter module corresponding to each battery cluster is controlled to operate at the corresponding balancing power.

[0117] In a possible implementation, the electrical parameter comprises an SOC value; the device 100 provided in this embodiment further comprises a recovery module, and the recovery module specifically comprises:

[0118] A single-cluster balancing completion judgment unit is configured to judge whether each battery cluster completes power balancing respectively, and control the converter module corresponding to the battery cluster that completes power balancing to be inhibited from charging and discharging;

[0119] A whole balancing completion judgment unit is configured to judge whether all the battery clusters complete power balancing, and if all the battery clusters complete power balancing, the converter module corresponding to each battery cluster is closed;

[0120] A recovery unit is configured to judge whether a difference between a maximum value of the total voltage of the battery clusters and a minimum value of the total voltage of the battery clusters in all the battery clusters is less than a preset voltage threshold, and 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, the connection between each switch module and the corresponding battery cluster and the direct-current bus is controlled to be closed;

[0121] An energy storage converter starting unit is configured to control the energy storage converter to start.

[0122] In one possible implementation, the overall balance completion judgment unit includes:

[0123] If all battery clusters trigger the preset prohibition condition, or if the difference between the maximum value and the minimum value of the total voltage of all battery clusters is less than the preset voltage threshold, then it is determined that all battery clusters have completed power balancing.

[0124] The preset prohibition conditions include conditions prohibiting charging and / or conditions prohibiting discharging.

[0125] Figure 5 This is a schematic diagram of the controller provided in an embodiment of the present invention. Figure 5 As shown, the controller 5 in this embodiment includes a processor 50 and a memory 51. The memory 51 stores a computer program 52, and the processor 50 calls and runs the computer program 52 stored in the memory 51 to execute the steps in the above embodiments of the offline equalization control method for energy storage systems, for example... Figure 3 The steps S101 to S103 are shown. Alternatively, the processor 50 is used to call and run the computer program 52 stored in the memory 51 to implement the functions of each module / unit in the above-described device embodiments, for example... Figure 4 The functions of modules 110 to 130 are shown.

[0126] For example, the computer program 52 can be divided into one or more modules / units, which are stored in the memory 51 and executed by the processor 50 to complete the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program 52 in the controller 5. For example, the computer program 52 can be divided into... Figure 4 Modules 110 to 130 are shown.

[0127] The controller 5 can be a computing device such as a desktop computer, laptop, handheld computer, or cloud server. The controller 5 may include, but is not limited to, a processor 50 and a memory 51. Those skilled in the art will understand that... Figure 5 This is merely an example of controller 5 and does not constitute a limitation on controller 5. It may include more or fewer components than shown, or combine certain components, or different components. For example, the controller may also include input / output devices, network access devices, buses, etc.

[0128] The processor 50 can be a central processing unit (CPU), and can also be other general-purpose processors, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0129] The memory 51 can be an internal storage unit of the controller 5, such as a hard disk or a memory of the controller 5. The memory 51 can also be an external storage device of the controller 5, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. Further, the memory 51 can also include both the internal storage unit and the external storage device of the controller 5. The memory 51 is used to store the computer program and other programs and data required by the controller. The memory 51 can also be used to temporarily store data that has been output or will be output.

[0130] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above functional units and modules is exemplified, and in actual application, the above functions can be completed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules to complete all or part of the above-described functions. Each functional unit and module in the embodiment can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit, and the integrated unit can be realized in the form of hardware or in the form of software functional unit. In addition, the specific names of each functional unit and module are only for easy distinction, and do not limit the protection scope of the present application. The specific working process of the units and modules in the above system can refer to the corresponding process in the foregoing method embodiments, which will not be described here.

[0131] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described or recorded in detail in a certain embodiment can refer to the relevant description of other embodiments.

[0132] Those skilled in the art can understand that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0133] In the embodiments provided by the present application, it should be understood that the disclosed apparatus / controller and method can be implemented in other ways. For example, the apparatus / controller embodiments described above are merely schematic. For example, the division of the modules or units is merely a logical function division, and there can be another division manner in actual implementation. For example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed coupling or direct coupling or communication connection between each other can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or in other forms.

[0134] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e. they can be located in one place, or distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0135] In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically independently, or two or more units can be integrated into one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0136] The integrated module / unit, if implemented in the form of a software function unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on such understanding, all or part of the processes in the above-mentioned embodiment methods can also be completed by a computer program instructing related hardware, and the computer program can be stored in a computer readable storage medium. The computer program can implement the steps of each energy storage system offline equalization control method embodiment when executed by a processor. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or some intermediate forms, etc. The computer readable medium can include any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content included in the computer readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction, for example, in some jurisdictions, according to legislation and patent practice, the computer readable medium does not include electrical carrier signals and telecommunication signals.

[0137] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. An off-line equalization control method for an energy storage system, characterized by, The application is applied to an energy storage system, the energy storage system comprises a controller, an energy storage converter, a plurality of battery clusters and a high-voltage box corresponding to each battery cluster; the high-voltage box comprises a switching module and a conversion module; each battery cluster is connected with a first end of the corresponding switching module and a first end of the conversion module, the second end of each switching module is connected with the energy storage converter through a DC bus; the second end of each conversion module is connected with a three-phase power distribution end of the energy storage system; The method comprises: obtaining the electrical parameters of each battery cluster, and determining whether there is a battery cluster with unbalanced power according to the electrical parameters of each battery cluster; if there is a battery cluster with unbalanced power, then controlling the energy storage converter and the switching module corresponding to each battery cluster to be closed; starting the conversion module corresponding to each battery cluster, and controlling the conversion module corresponding to each battery cluster to operate at a respective equalization power, so that each battery cluster performs power balancing through the three-phase power distribution end; the equalization power of each conversion module is related to the electrical parameters of the corresponding battery cluster; the electrical parameters include battery voltage and SOC value; the determination of whether there is a battery cluster with unbalanced power according to the electrical parameters of each battery cluster comprises: calculating the difference between the current SOC value and the SOC reference value of each battery cluster to obtain the power deviation value corresponding to each battery cluster; if the power deviation value of a battery cluster is greater than a preset deviation threshold value, and the battery voltage difference between the batteries in the battery cluster exceeds a preset voltage threshold value, then it is determined that the power of the battery cluster is unbalanced; controlling the conversion module corresponding to each battery cluster to perform power balancing for the corresponding battery cluster at a respective equalization power comprises: determining the equalization power of the corresponding conversion module according to the SOC value to be balanced of each battery cluster; controlling the conversion module corresponding to each battery cluster to operate at the corresponding equalization power.

2. The off-line equalization control method of an energy storage system according to claim 1, wherein, When the battery cluster performs power balancing in charging mode, the SOC reference value is the maximum SOC value of all battery clusters in the energy storage system; when the battery cluster performs power balancing in discharging mode, the SOC reference value is the minimum SOC value of all battery clusters in the energy storage system.

3. The off-line equalization control method of an energy storage system according to claim 1, wherein, the switching module comprises a main contactor, one end of the main contactor is connected with the DC bus, and the other end is connected with the corresponding battery cluster; if there is a battery cluster with unbalanced power, then controlling the energy storage converter and the switching module corresponding to each battery cluster to be closed comprises: if there is a battery cluster with unbalanced power, then when the preset inhibition condition of the energy storage system is triggered, the energy storage converter is inhibited from charging and discharging; the preset inhibition condition comprises a charging inhibition condition and a discharging inhibition condition; after receiving the cluster-level balancing confirmation instruction of the user, controlling the energy storage converter and all main contactors to be closed.

4. The off-line equalization control method of an energy storage system according to claim 1, wherein, the SOC value to be balanced is positively correlated with the equalization power, and the SOC value to be balanced is the difference between the current SOC value and the target SOC value of the battery cluster.

5. The off-line equalization control method of an energy storage system according to claim 1, wherein, after controlling the conversion module corresponding to each battery cluster to perform power balancing for the corresponding battery cluster at a respective equalization power, the method further comprises: respectively determine whether each battery cluster completes the charge balance, and control the corresponding current conversion module of the battery cluster to prohibit charging and discharging when the battery cluster completes the charge balance; determine whether all battery clusters have completed the charge balance, and close the corresponding current conversion module of each battery cluster when all battery clusters have completed the charge balance; 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 battery clusters is less than a preset voltage threshold, and control each switch module to close the connection between the corresponding battery cluster and the DC bus when 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; control the energy storage converter to start.

6. The off-line equalization control method of an energy storage system according to claim 1, wherein, The determination of whether all battery clusters have completed the charge balance comprises: determine that all battery clusters have completed the charge balance when all battery clusters trigger a preset prohibition condition or 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 a preset voltage threshold. The preset prohibition condition comprises a charging prohibition condition and / or a discharging prohibition condition.

7. An off-line equalization control device for an energy storage system, comprising: The application is applied to an energy storage system, which comprises a controller, an energy storage converter, a plurality of battery clusters, and a high-voltage box corresponding to each battery cluster. The high-voltage box comprises a switch module and a current conversion module. Each battery cluster is connected with the first end of the corresponding switch module and the first end of the current conversion module. The second end of each switch module is connected with the energy storage converter through a DC bus. The second end of each current conversion module is connected with a three-phase power distribution end of the energy storage system. The device comprises: a charge balance determination module configured to obtain electrical parameters of each battery cluster and determine whether there is a battery cluster with unbalanced charge according to the electrical parameters of each battery cluster; an offline control module configured to control the energy storage converter and the switch module corresponding to each battery cluster to be closed when there is a battery cluster with unbalanced charge; an equalization management module configured to start the current conversion module corresponding to each battery cluster and control the current conversion module corresponding to each battery cluster to operate at a respective equalization power, so that each battery cluster performs charge balance through the three-phase power distribution end. The equalization power of each current conversion module is related to the electrical parameters of the corresponding battery cluster. The electrical parameters comprise battery voltage and SOC value. The charge balance determination module comprises: calculating the difference between the current SOC value and the SOC reference value of each battery cluster to obtain the charge deviation value corresponding to each battery cluster; determining that the charge of the battery cluster is unbalanced when the charge deviation value of the battery cluster is greater than a preset deviation threshold and the battery voltage difference between the batteries in the battery cluster exceeds a preset voltage threshold. The equalization management module comprises: determining the equalization power of the corresponding current conversion module according to the SOC value to be balanced of each battery cluster; controlling the current conversion module corresponding to each battery cluster to operate at the corresponding equalization power.

8. A controller characterized by comprising: The device comprises a processor and a memory. The memory is configured to store a computer program. The processor is configured to call and run the computer program stored in the memory to execute the offline equalization control method of the energy storage system according to any one of claims 1 to 6.

9. A computer-readable storage medium storing a computer program, the computer program comprising instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 1 to 8. The computer program, which is executed by a processor, realizes the steps of the off-line equalization control method of the energy storage system as claimed in any one of claims 1 to 6.

10. An energy storage system characterized by, The controller as claimed in claim 8 is included.

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