Centralized power storage system adaptive equalization control system and control method thereof

Abstract

This invention relates to an adaptive equalization control system and its control method for a centralized power energy storage system, belonging to the field of energy storage system technology. The output of the battery cluster is connected to a series variable resistor unit. The battery management system establishes an information interaction connection with the battery cluster, variable resistor unit, high-voltage box, combiner cabinet, and energy storage converter. The variable resistor unit outputs a matched resistance value according to control commands, eliminating the problem of inconsistent inter-cluster current caused by impedance differences. The input of the high-voltage box is connected to the output of the battery cluster, and the output is connected to the input of the combiner cabinet. The DC side of the energy storage converter is connected to the output of the combiner cabinet, with multiple battery clusters sharing one energy storage converter. This invention improves the consistency of inter-cluster charging and discharging current, reduces inter-cluster voltage difference, reduces the risk of inter-cluster circulating current, eliminates the need for manual maintenance, reduces system operation and maintenance costs, reduces the degree of inter-cluster resistance imbalance, improves cell charging and discharging consistency, and extends the service life of the energy storage system.

Description

Technical Field

[0001] This invention relates to an adaptive equalization control system and control method for a centralized power energy storage system, belonging to the field of energy storage system technology. Background Technology

[0002] In the application of power energy storage systems, centralized power energy storage systems generally adopt a multi-cluster parallel operation mode. Under this operation mode, after long-term operation, the consistency of the cells will deteriorate, which will directly lead to an increase in the voltage difference between battery clusters and thus generate inter-cluster circulating current. At the same time, during long-term operation, the internal resistance of the cells themselves will vary, and the connecting cables between clusters will also age. All of these factors will cause impedance differences between battery clusters, ultimately leading to inconsistent charging and discharging currents between clusters.

[0003] To maintain voltage consistency between clusters, existing technologies typically incorporate a pre-charge circuit to maintain inter-cluster voltage differences, thereby ensuring the stable operation of lithium-ion battery energy storage systems. However, when this method is used, relying solely on the pre-charge circuit to eliminate the voltage difference when it exceeds a certain threshold becomes too time-consuming. In practical applications, manual intervention is required for maintenance, leading to a significant increase in labor costs. The core reason for this problem is that inconsistencies in inter-cluster currents continuously exacerbate the inter-cluster voltage difference.

[0004] Therefore, how to effectively improve the consistency of current between clusters has become a key technical problem that urgently needs to be solved in the field of centralized power storage. Summary of the Invention

[0005] To address the problems existing in the background technology, the present invention provides an adaptive equalization control system and control method for a centralized power energy storage system.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: an adaptive balancing control system for a centralized power storage system, comprising... The battery cluster consists of several battery cells connected in series to provide power to the entire energy storage system. Multiple battery clusters are connected in parallel, and each battery cluster has a variable resistor unit connected in series at its output terminal to achieve independent adjustment of the internal resistance of each battery cluster. The battery management system establishes information interaction connections with battery clusters, variable resistor units, high-voltage boxes, combiner cabinets, and energy storage converters. It is used to realize relay control, current detection, voltage detection, and fuse status detection of the battery stack system, and at the same time complete information interaction with each component and issue control commands. The variable resistor unit is connected in series with each battery cluster. It calculates and judges the resistance difference between the clusters by collecting the voltage and current data of the battery clusters, and then outputs a matching resistance value according to the control command to eliminate the problem of inconsistent current between the clusters caused by impedance differences. The high-voltage box, as an intermediate control unit connecting the battery cluster and the energy storage converter, has its input end connected to the output end of the parallel battery cluster and its output end connected to the input end of the combiner cabinet. It is used to realize the control, protection and data communication functions of the battery cluster. The combiner cabinet, connected to the high-voltage box, is used to collect the DC power generated by each battery cluster and form a large current output. It also has circuit protection and data communication functions. The energy storage converter, with its DC side connected to the output of the combiner cabinet, is an energy conversion device used to bidirectionally convert the DC power output from the combiner cabinet to the AC power. Multiple battery clusters share one energy storage converter.

[0007] Furthermore, the variable resistor unit includes a MOS field-effect transistor and a resistor matrix constructed from resistors. The gate G of the MOS field-effect transistor receives a binary encoded signal sent by the MCU. The connection and removal of resistors are controlled by the signal level to adjust the output resistance value of the resistor matrix, that is, to adjust the resistance value of the variable resistor unit.

[0008] Furthermore, the resistor matrix uses resistors with an accuracy of 0.1%, and the basic resistance value levels of 100mΩ, 10mΩ and 1mΩ are achieved by connecting 1Ω resistors in parallel one by one.

[0009] Furthermore, the connection and removal of the resistor controlled by the signal level are specifically as follows: a low level of 0 connects the corresponding resistor, and a high level of 1 removes the corresponding resistor.

[0010] Furthermore, the resistor matrix outputs a resistance value. The formula for calculation is: In the formula: This indicates the number of 100mΩ, 10mΩ, and 1mΩ resistance levels that can be connected.

[0011] The present invention discloses a control method for an adaptive balancing control system of a centralized power energy storage system, the method comprising the following steps: S1: Cable impedance basic compensation; S101: In the initial stage of system commissioning, technicians calculate the impedance value of each battery cluster cable based on the actual cable laying length between each battery cluster and the DC side of the energy storage converter, using the circuit impedance calculation formula, and enter the calculated data into the battery management system. S102: The battery management system automatically extracts the maximum impedance value; S103: The battery management system calculates the difference between the impedance of each battery cluster and the maximum impedance value; S104: The battery management system sends an initial resistance setting command to the variable resistor unit of each battery cluster. After receiving the command, the MCU of each variable resistor unit sends a binary code to the gate of the corresponding MOS field-effect transistor to control the resistor matrix to connect the corresponding compensation resistor, thereby completing the basic compensation of the cable impedance.

[0012] S2: Real-time current acquisition and target value setting; S201: During normal system operation, the battery management system collects the output current value of each battery cluster in real time at a fixed sampling frequency through its current detection module, and also collects the total voltage data of each battery cluster to assist in judgment. S202: The battery management system automatically calculates the average current value based on the real-time collected current value; S203: Set the average current value as the target current value for inter-cluster current consistency adjustment.

[0013] S3: Calculation of target resistance value; S301: The battery management system compares the real-time current value of each battery cluster with the target current value Iavg one by one. S302: For battery clusters with current values ​​greater than the average current value, calculate the impedance value that needs to be increased; for battery clusters with current values ​​less than the average current value, calculate the impedance value that needs to be decreased. S303: Combining Ohm's law of the circuit and the operating characteristics of the system, the target resistance value that needs to be adjusted for each variable resistor unit of the battery cluster is obtained.

[0014] S4: Resistance adjustment of the variable resistor unit.

[0015] S401: The battery management system converts the calculated target resistance values ​​of each battery cluster into corresponding binary code instructions and sends them to the variable resistance units of each battery cluster. S402: After receiving the binary encoded instruction, the MCU of the variable resistor unit sends the corresponding level signal to the gate G of each MOS field-effect transistor, adjusts the output resistance value of the resistor matrix to the target resistance value, realizes the real-time adjustment of the external internal resistance of each battery cluster, makes the output current of each battery cluster approach the target current value, and finally achieves the basic consistency of the current between clusters.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention, by connecting variable resistor units in series with each battery cluster and employing an adaptive equalization control strategy, first performs precise basic compensation for cable impedance differences, and then dynamically adjusts the output resistance value of the variable resistor units according to the real-time current deviation between clusters. This effectively improves the consistency of charging and discharging current between clusters, significantly reduces inter-cluster voltage difference, reduces the risk of inter-cluster circulating current, eliminates the need for manual intervention in maintenance, and significantly reduces system operation and maintenance costs. At the same time, it can adaptively match the internal resistance differences caused by cell aging, cable aging, and cell temperature changes, reduce the degree of resistance imbalance between clusters, improve the consistency of cell charging and discharging, extend the service life of the energy storage system, and thus improve the overall operating efficiency of the energy storage system. Attached Figure Description

[0017] Figure 1 This is a flowchart of the control method of the present invention; Figure 2 This is the control circuit diagram of the control system of the present invention; Figure 3 This is the control circuit diagram for the variable resistor unit. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] An adaptive balancing control system for centralized power energy storage systems is mainly applied in prefabricated container energy storage scenarios such as power plants, photovoltaic power generation, electric power generation, and microgrid energy storage. A battery cluster consists of several battery cells connected in series to provide power to the entire energy storage system. According to the power requirements of the energy storage system, multiple battery clusters are connected in parallel. Each battery cluster has a variable resistor unit connected in series at its output terminal to achieve independent adjustment of the internal resistance of each battery cluster. The battery management system establishes information interaction connections with battery clusters, variable resistor units, high-voltage boxes, combiner cabinets, and energy storage converters. It is used to realize relay control, current detection, voltage detection, and fuse status detection of the battery stack system, and at the same time complete information interaction with each component and issue control commands. The signal acquisition terminal is connected to each battery cluster, high-voltage box, and combiner cabinet to collect data such as current, voltage, and fuse status; the control terminal is connected to each variable resistor unit, relay in the high-voltage box, and energy storage converter to issue control commands and realize information interaction.

[0020] The variable resistor unit is connected in series with each battery cluster. It calculates and judges the resistance difference between the clusters by collecting the voltage and current data of the battery clusters, and then outputs a matching resistance value according to the control command to eliminate the problem of inconsistent current between the clusters caused by impedance differences. The variable resistor unit has the characteristics of adjustable output resistance and a large adjustable range, which can effectively improve the current consistency problem caused by factors such as inconsistent cable length, cable aging, and inconsistent internal resistance of the battery cells. The high-voltage box, as an intermediate control unit connecting the battery clusters and the energy storage converter, has its input terminal connected to the output terminal of the parallel battery clusters. The high-voltage box independently controls and protects the output circuits of each battery cluster. Its output terminal is connected to the input terminal of the combiner cabinet to realize the control, protection and data communication functions of the battery clusters. The combiner cabinet, connected to the high-voltage box, is used to collect the DC power generated by each battery cluster and form a large current output that meets the input requirements of the energy storage converter. It also has circuit protection and data communication functions. The energy storage converter, with its DC side connected to the output of the combiner cabinet, is a power conversion device used to bidirectionally convert the DC power output from the combiner cabinet to the AC power, enabling power interaction with the power grid. It has certain control functions and can be flexibly configured with various power outputs according to actual application needs. Multiple battery clusters share one energy storage converter, and the battery management system controls the relays within the cluster to achieve current consistency.

[0021] Furthermore, the variable resistor unit includes a MOS field-effect transistor (MOS transistor) and a resistor matrix constructed from resistors. The gate G of the MOS field-effect transistor receives a binary coded signal sent by the MCU (microcontroller unit). The connection and removal of resistors are controlled by the signal level. By sending different binary codes according to actual needs, the output resistance value of the resistor matrix can be adjusted, that is, the resistance value of the variable resistor unit can be adjusted.

[0022] Furthermore, the resistor matrix uses resistors with an accuracy of 0.1%. By connecting 1Ω resistors in parallel one by one, the basic resistance value levels of 100mΩ, 10mΩ and 1mΩ are achieved. By connecting this resistor matrix in series in the battery cluster circuit, the internal resistance of each battery cluster can be finely adjusted.

[0023] Furthermore, the connection and removal of the resistor controlled by the signal level are specifically as follows: a low level of 0 connects the corresponding resistor, and a high level of 1 removes the corresponding resistor.

[0024] Furthermore, the resistor matrix outputs a resistance value. The formula for calculation is: In the formula: This indicates the number of 100mΩ, 10mΩ, and 1mΩ resistance levels that can be connected.

[0025] The present invention discloses a control method for an adaptive balancing control system of a centralized power energy storage system, the method comprising the following steps: S1: Cable impedance basic compensation; S101: In the initial stage of system commissioning, technicians calculate the impedance value of each battery cluster cable based on the actual cable laying length between each battery cluster and the DC side of the energy storage converter, using the circuit impedance calculation formula, and enter the calculated data into the battery management system. S102: The battery management system automatically extracts the maximum impedance value; S103: The battery management system calculates the difference between the impedance of each battery cluster and the maximum impedance value; S104: The battery management system sends an initial resistance setting command to the variable resistor unit of each battery cluster. After receiving the command, the MCU of each variable resistor unit sends a binary code to the gate of the corresponding MOS field-effect transistor, controls the resistor matrix to connect the corresponding compensation resistor, completes the basic compensation of the cable impedance, and eliminates the impedance inconsistency caused by the difference in cable length among the battery clusters.

[0026] S2: Real-time current acquisition and target value setting; S201: During normal system operation, the battery management system collects the output current value of each battery cluster in real time at a fixed sampling frequency through its current detection module, and also collects the total voltage data of each battery cluster to assist in judgment. S202: The battery management system automatically calculates the average current value based on the real-time collected current value; S203: Set the average current value as the target current value for inter-cluster current consistency adjustment, and use it as the reference for subsequent resistance adjustment.

[0027] S3: Calculation of target resistance value; S301: The battery management system compares the real-time current value of each battery cluster with the target current value Iavg one by one. S302: For battery clusters with current values ​​greater than the average current value, calculate the impedance value that needs to be increased; for battery clusters with current values ​​less than the average current value, calculate the impedance value that needs to be decreased. S303: Combining Ohm's law of the circuit and the operating characteristics of the system, the target resistance value that needs to be adjusted for each variable resistor unit of the battery cluster is obtained.

[0028] S4: Resistance adjustment of the variable resistor unit.

[0029] S401: The battery management system converts the calculated target resistance values ​​of each battery cluster into corresponding binary code instructions and sends them to the variable resistance units of each battery cluster. S402: After receiving the binary encoded instruction, the MCU of the variable resistor unit sends the corresponding level signal to the gate G of each MOS field-effect transistor. By connecting the resistor with a low level and removing the resistor with a high level, the output resistance of the resistor matrix is ​​adjusted to the target resistance value, thereby realizing the real-time adjustment of the external internal resistance of each battery cluster. This makes the output current of each battery cluster approach the target current value, and finally achieves the basic consistency of the current between the clusters.

[0030] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0031] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An adaptive balancing control system for a centralized power storage system, characterized in that: include: The battery cluster consists of several battery cells connected in series to provide power to the entire energy storage system. Multiple battery clusters are connected in parallel, and each battery cluster has a variable resistor unit connected in series at its output terminal to achieve independent adjustment of the internal resistance of each battery cluster. The battery management system establishes information interaction connections with battery clusters, variable resistor units, high-voltage boxes, combiner cabinets, and energy storage converters. It is used to realize relay control, current detection, voltage detection, and fuse status detection of the battery stack system, and at the same time complete information interaction with each component and issue control commands. The variable resistor unit is connected in series with each battery cluster. It calculates and judges the resistance difference between the clusters by collecting the voltage and current data of the battery clusters, and then outputs a matching resistance value according to the control command to eliminate the problem of inconsistent current between the clusters caused by impedance differences. The high-voltage box, as an intermediate control unit connecting the battery cluster and the energy storage converter, has its input end connected to the output end of the parallel battery cluster and its output end connected to the input end of the combiner cabinet. It is used to realize the control, protection and data communication functions of the battery cluster. The combiner cabinet, connected to the high-voltage box, is used to collect the DC power generated by each battery cluster and form a large current output. It also has circuit protection and data communication functions. The energy storage converter, with its DC side connected to the output of the combiner cabinet, is an energy conversion device used to bidirectionally convert the DC power output from the combiner cabinet to the AC power. Multiple battery clusters share one energy storage converter.

2. The adaptive balancing control system for a centralized power storage system according to claim 1, characterized in that: The variable resistor unit includes a MOS field-effect transistor and a resistor matrix constructed from resistors. The gate G of the MOS field-effect transistor receives a binary coded signal sent by the MCU. The connection and removal of resistors are controlled by the signal level to adjust the output resistance value of the resistor matrix, that is, to adjust the resistance value of the variable resistor unit.

3. The adaptive balancing control system for a centralized power storage system according to claim 2, characterized in that: The resistor matrix uses resistors with an accuracy of 0.1%, and achieves basic resistance value levels of 100mΩ, 10mΩ, and 1mΩ by connecting 1Ω resistors in parallel one by one.

4. The adaptive balancing control system for a centralized power storage system according to claim 2, characterized in that: The connection and removal of the resistor controlled by the signal level are as follows: a low level of 0 connects the corresponding resistor, and a high level of 1 removes the corresponding resistor.

5. The adaptive balancing control system for a centralized power storage system according to claim 2, characterized in that: The resistor matrix outputs resistance value The formula for calculation is: In the formula: This indicates the number of 100mΩ, 10mΩ, and 1mΩ resistance levels that can be connected.

6. A control method for an adaptive balancing control system of a centralized power storage system according to any one of claims 1-5, characterized in that: The method includes the following steps: S1: Cable impedance basic compensation; S2: Real-time current acquisition and target value setting; S3: Calculation of target resistance value; S4: Resistance adjustment of the variable resistor unit.

7. The control method for an adaptive equalization control system of a centralized power storage system according to claim 6, characterized in that: S1 includes the following steps: S101: In the initial stage of system commissioning, technicians calculate the impedance value of each battery cluster cable based on the actual cable laying length between each battery cluster and the DC side of the energy storage converter, using the circuit impedance calculation formula, and enter the calculated data into the battery management system. S102: The battery management system automatically extracts the maximum impedance value; S103: The battery management system calculates the difference between the impedance of each battery cluster and the maximum impedance value; S104: The battery management system sends an initial resistance setting command to the variable resistor unit of each battery cluster. After receiving the command, the MCU of each variable resistor unit sends a binary code to the gate of the corresponding MOS field-effect transistor to control the resistor matrix to connect the corresponding compensation resistor, thereby completing the basic compensation of the cable impedance.

8. The control method for an adaptive equalization control system of a centralized power storage system according to claim 7, characterized in that: S2 includes the following steps: S201: During normal system operation, the battery management system collects the output current value of each battery cluster in real time at a fixed sampling frequency through its current detection module, and also collects the total voltage data of each battery cluster to assist in judgment. S202: The battery management system automatically calculates the average current value based on the real-time collected current value; S203: Set the average current value as the target current value for inter-cluster current consistency adjustment.

9. The control method for an adaptive equalization control system of a centralized power storage system according to claim 8, characterized in that: S3 includes the following steps: S301: The battery management system compares the real-time current value of each battery cluster with the target current value Iavg one by one. S302: For battery clusters with current values ​​greater than the average current value, calculate the impedance value that needs to be increased; for battery clusters with current values ​​less than the average current value, calculate the impedance value that needs to be decreased. S303: Combining Ohm's law of the circuit and the operating characteristics of the system, the target resistance value that needs to be adjusted for each variable resistor unit of the battery cluster is obtained.

10. The control method for an adaptive equalization control system of a centralized power storage system according to claim 9, characterized in that: S4 includes the following steps: S401: The battery management system converts the calculated target resistance values ​​of each battery cluster into corresponding binary code instructions and sends them to the variable resistance units of each battery cluster. S402: After receiving the binary encoded instruction, the MCU of the variable resistor unit sends the corresponding level signal to the gate G of each MOS field-effect transistor to adjust the output resistance value of the resistor matrix to the target resistance value, thereby realizing the real-time adjustment of the external internal resistance of each battery cluster and making the output current of each battery cluster approach the target current value.

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