Control method for solving non-uniform parallel electric quantity of energy storage system

Abstract

The invention relates to the field of parallel energy storage system control application, and discloses a control method for solving uneven parallel electric quantity of an energy storage system, which comprises the following steps of: S1, performing power-on self-test on an energy storage battery cluster, completing automatic address division and setting initial operation power; s2, when any energy storage battery cluster triggers protection, the BMS reports state information to an EMS energy management system; s3, the EMS issues an instruction to disconnect the connection of the corresponding battery clusters; s4, adjusting the total operation power of the energy storage system by the EMS energy management system, and circularly executing the step S2 until all the battery clusters are disconnected; and S5, circularly scanning and checking an execution result. Any energy storage battery cluster is independently disconnected when reaching the protection threshold value, and the total power of the system is synchronously adjusted to maintain the operation multiplying power of the remaining battery clusters unchanged, so that the effect that each energy storage battery cluster connected in parallel can complete the respective complete charging or discharging process is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of parallel energy storage system control applications, and in particular to a control method for solving uneven charge in parallel energy storage systems. Background Art

[0002] With the development of society and changes in the international landscape, energy issues are becoming increasingly prominent. Demand for energy storage systems, particularly those using lithium-ion batteries, continues to grow globally. Storing excess power from the grid in energy storage systems for use during peak hours or in emergencies plays a crucial role in saving electricity costs and ensuring energy security. To meet the demands of high-power and high-capacity applications, current energy storage systems generally utilize a parallel connection of multiple energy storage battery clusters to increase the system's total capacity and charge / discharge rate.

[0003] However, maintaining balanced charge across multiple energy storage battery clusters in parallel poses a core and pressing technical challenge. Due to variations in battery manufacturing, materials, and aging, as well as the inevitable circulation issues in parallel circuits, the inconsistencies between the states of individual energy storage battery clusters increase with age. This inconsistency inevitably leads to one energy storage battery cluster reaching its preset overcharge or over-discharge protection threshold first during the charge and discharge process.

[0004] Existing energy storage system control strategies typically issue a shutdown command to the entire system upon detecting a battery cluster triggering protection, halting the charging or discharging of all battery clusters. This protection approach forces the entire system to shut down when the battery cluster that first reaches its limit stops, forcing all remaining battery clusters that haven't yet reached their charge or discharge limits to stop as well. This directly wastes the energy storage system's available capacity, preventing all batteries from being fully charged or fully discharged during discharge, significantly reducing the overall system's energy efficiency.

[0005] Furthermore, this integrated, coordinated control approach also reduces the system's operational robustness and hardware compatibility. During the system's power-on self-test phase, if a single energy storage battery cluster fails, the existing control logic prevents the entire system from operating, rather than simply isolating the faulty unit and utilizing the remaining healthy units. This design not only reduces the system's fault tolerance in the face of localized failures but also places excessively high demands on the consistency of parallel battery clusters, limiting the system's flexibility in using batteries of different batches or capacities for expansion or repair and replacement.

[0006] Ultimately, this frequent system startup and shutdown, caused by the status of individual cells, directly impacted the reliability of the energy storage system's power supply to downstream loads. Furthermore, the inability to fully execute the planned charge and discharge strategy reduced the system's profitability. Summary of the Invention

[0007] In response to the shortcomings of the existing technology, the present invention provides a control method for solving the uneven power distribution in parallel energy storage systems. It solves the problem that in an energy storage system with multiple battery clusters connected in parallel, a single battery cluster reaches the charge and discharge protection threshold first, causing the entire system to stop operating prematurely, thereby resulting in a reduction in the total available capacity of the system and low energy utilization efficiency.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions: A control method for solving the uneven charge of parallel energy storage systems, comprising the following steps: S1. Performing a power-on self-test on the multiple energy storage battery clusters to determine the number of energy storage battery clusters online in real time, and performing automatic addressing and initial setting of system operating power accordingly; S2. When the first energy storage battery cluster triggers overcharge or over-discharge protection, the BMS battery management system of the first energy storage battery cluster reports its status information to the EMS energy management system; S3. After receiving the status information, the EMS energy management system issues a power disconnection instruction to disconnect the first energy storage battery cluster from the energy storage system; S4, the EMS energy management system sends a power limit instruction to the charging module or the discharging module to adjust the operating power of the energy storage system, and then returns to step S2 until all energy storage battery clusters reach the preset charging or discharging cut-off state; S5. Finally, a cyclic scanning test is performed to confirm that the power off instruction and the power limit instruction are executed.

[0009] Preferably, in step S1, the power-on self-test, automatic addressing and initial setting respectively include the following steps: Power-on self-test: The BMS battery management system of each energy storage battery cluster performs self-test; Automatic addressing: When there are energy storage battery clusters that fail self-test, the EMS energy management system will re-address the remaining energy storage battery clusters that pass self-test; Initial setting: The EMS energy management system adjusts the system operating power according to the number of real-time online energy storage battery clusters.

[0010] Preferably, after re-addressing the remaining energy storage battery clusters that have passed the self-test, it is necessary to re-check the number of the energy storage battery clusters that have passed the self-test to confirm that no energy storage battery cluster is omitted in the automatic addressing process.

[0011] Preferably, in step S2, the status information includes: Overcharge protection status information, corresponding to the charging status; Over-discharge protection status information corresponds to the discharge status.

[0012] Preferably, in step S3, the EMS energy management system sends the power disconnection instruction through the I / O interface and dry contact signal.

[0013] Preferably, in step S4, the output power limited by the power limit instruction , which is calculated as follows: ; Where, The system is disconnected After the battery cluster is protected, the power to be run should be: is the initial total power of the energy storage system; is the total number of battery clusters initially in the energy storage system; The number of battery clusters that have triggered protection and been disconnected.

[0014] The present invention provides a control method for solving the uneven charge in parallel energy storage systems. It has the following beneficial effects: 1. The present invention independently disconnects any energy storage battery cluster when it reaches a protection threshold during the charge and discharge process, and simultaneously adjusts the total system power to maintain the operating rate of the remaining battery clusters unchanged. This ensures that each parallel energy storage battery cluster can complete its own complete charge or discharge process. This solves the technical problem in the prior art of reduced overall available capacity of the energy storage system due to imbalanced power between battery clusters caused by parallel circulation or individual battery differences. This achieves in-depth utilization of the total available power of the energy storage system and improves the system's power utilization efficiency.

[0015] 2. The present invention performs self-inspections on all energy storage battery clusters during the power-on phase, automatically isolates faulty clusters, re-addresses remaining healthy clusters, and independently controls each battery cluster according to its real-time status during operation. This achieves the effect of automatically shielding faulty units at startup and allowing battery clusters of different capacities to work together during operation. This solves the technical problem that traditional parallel systems require high consistency in battery clusters and that a single unit failure will cause the entire system to be unable to operate. This achieves flexible expansion of the energy storage system's hardware configuration and improved fault tolerance in operation, thereby enhancing the robustness of the system.

[0016] 3. The present invention takes a single battery cluster offline instead of shutting down the entire system after it reaches its operating limit, and dynamically allocates power to ensure continuous power supply to the back-end load. This achieves the effect of releasing the available energy of all battery clusters one by one without interrupting system operation. It solves the technical problem of the entire energy storage system stopping power supply due to the triggering of protection by a single battery cluster, resulting in waste of residual energy and power supply interruption, and achieves reliable power supply to the back-end load. Without affecting the upper-level application strategy, it improves the operating yield of the entire energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a flow chart of the method steps of the present invention; Figure 2 Schematic diagram of the self-checking function framework of the present invention; Figure 3 This is a schematic diagram of the charging function framework of the present invention; Figure 4 Schematic diagram of the discharge function framework of the present invention. DETAILED DESCRIPTION

[0018] Please see the attached Figure 1 -Attached Figure 4 The embodiment of the present invention provides a control method for solving the uneven charge of a parallel energy storage system, comprising the following steps: S1. Perform power-on self-test on multiple energy storage battery clusters to determine the number of energy storage battery clusters online in real time, and perform automatic addressing and initial setting of system operating power accordingly; S2. When the first energy storage battery cluster triggers overcharge or over-discharge protection, the BMS battery management system of the first energy storage battery cluster reports its status information to the EMS energy management system; S3. After receiving the status information, the EMS energy management system issues a power disconnection instruction to disconnect the first energy storage battery cluster from the energy storage system. S4. The EMS energy management system sends a power limit instruction to the charging module or the discharging module to adjust the operating power of the energy storage system, and then returns to step S2 until all energy storage battery clusters reach the preset charging or discharging cutoff state; S5. Finally, a cyclic scan test is performed to confirm that the power off instruction and the power limit instruction are executed.

[0019] In the above scheme, the specific details of step S1 are as follows: Specifically, step S1 aims to confirm the health status of the energy storage system before power-on and perform the initial configuration of operating parameters to ensure that all participating energy storage battery clusters are in a known, fault-free state when the system starts, and to set the initial operating capacity based on the actual available resources.

[0020] In one specific embodiment, this step begins by applying a low-voltage power supply to the entire energy storage system. Under this low-voltage condition, the battery management system (BMS) within each energy storage battery cluster is activated and first performs an internal self-test. This self-test verifies that the BMS's hardware circuitry, sensors, memory, and communication interfaces are functioning properly. Upon completion of the self-test, each BMS generates a status message containing its self-test results, which clearly indicate whether the self-test passed or failed.

[0021] Each BMS then proactively reports its status information, including self-test results, to the EMS via a pre-set communication bus. The EMS is responsible for receiving and summarizing the self-test results from all energy storage battery clusters.

[0022] The EMS analyzes this aggregated information. If it detects a self-test failure for one or more energy storage battery clusters, these clusters are identified as faulty. For each faulty cluster, the EMS issues a disable command to the BMS (Battery Management System) for that cluster via the communication ID, I / O interface, or dry contact signal. This command prevents the main power switch of the faulty cluster from closing, thereby physically isolating it and preventing it from connecting to the system's high-voltage parallel busbar.

[0023] After isolating all faulty clusters, the EMS re-addresses the remaining battery clusters whose status information indicates they have passed self-test. This process assigns unique, continuous logical addresses to these healthy battery clusters, allowing them to be accurately identified and controlled during subsequent operation.

[0024] After automatic addressing is complete and before the system is powered on, the EMS performs a count check. Specifically, the EMS compares the number of battery clusters to which logical addresses have been successfully assigned with the number of battery clusters that initially passed the self-test. If the two numbers match, it confirms that no healthy battery clusters were missed during the automatic addressing process.

[0025] Finally, after confirming the exact number of online, fault-free energy storage battery clusters, the EMS sets the initial operating power for the entire energy storage system based on this number. This setting ensures that the system's initial total charge or discharge power matches the actual available battery resources. After completing all of the above operations, the system enters a fully configured intelligent standby mode, awaiting subsequent charge or discharge instructions.

[0026] In the above scheme, the specific details of step S2 are as follows: Specifically, step S2 establishes a real-time reporting mechanism for operational boundary events from the energy storage battery cluster to the system control side. This step serves as the trigger for all subsequent dynamic balancing control actions, ensuring that the EMS accurately and promptly detects when any member of the parallel cluster reaches its charge or discharge limit.

[0027] In one specific embodiment, this step is continuously activated while the energy storage system is performing a charging or discharging task. Each energy storage battery cluster's BMS continuously monitors key internal parameters, particularly the maximum voltage (during charging) and minimum voltage (during discharging) of individual cells, as well as the overall battery cluster state of charge. These parameters are compared in real time with pre-set overcharge and over-discharge protection thresholds in the system.

[0028] When a parameter within any first energy storage battery cluster in the parallel cluster reaches a preset protection threshold for the first time (for example, during charging, the highest single cell voltage within it reaches the overcharge protection voltage value; or during discharging, its SOC reaches the preset minimum cutoff value), the BMS battery management system of the first energy storage battery cluster immediately determines that the protection condition is triggered.

[0029] Once the judgment condition is triggered, the BMS battery management system will immediately generate a status message. The status information is encapsulated in a specific data frame or message, and its content includes at least: The energy storage battery cluster is assigned a unique logical address in step S1, as well as an event code that clearly identifies the protection type. For example, one code is used to indicate overcharge protection triggering, and another different code is used to indicate over-discharge protection triggering.

[0030] The BMS then proactively sends this encapsulated status information data frame to the EMS via a pre-defined communication bus (e.g., CAN bus). The EMS, acting as the master control unit on the bus, continuously receives and analyzes data from all online BMSs. Successful reporting of this status information constitutes input to the EMS and directly initiates the subsequent S3 power disconnection control step.

[0031] In the above scheme, the specific details of step S3 are as follows: Specifically, step S3 aims to convert the status information reported in step S2 into a precise physical isolation action, that is, to reliably disconnect the first energy storage battery cluster that has reached the operating boundary from the parallel cluster, creating conditions for subsequent system power adjustment.

[0032] After receiving and parsing the status information reported in step S2, the EMS first extracts the logical address of the first energy storage battery cluster that triggered protection. Based on this logical address, the EMS locates the power switch control path uniquely corresponding to the first energy storage battery cluster.

[0033] Subsequently, the EMS energy management system generates and issues a power disconnection instruction. In a specific embodiment, the instruction is output via an I / O interface.

[0034] Specifically, the EMS energy management system changes the level state of a specific digital output port thereof, and the port is connected to the control end of the power switch of the first energy storage battery cluster through a control line, thereby driving the switch action.

[0035] In another specific embodiment, the command is issued via a dry contact signal. The EMS energy management system activates an internal relay coil corresponding to the first energy storage battery cluster, causing its contact state to change (for example, from normally closed to open). This contact is connected in series to a control circuit of a power switch, and the operation of the power switch is controlled by changing the on / off state of the circuit.

[0036] The power switch, such as a DC contactor or circuit breaker, performs a disconnection action after receiving a control signal from the EMS. This action physically cuts off the electrical connection between the first energy storage battery cluster and the energy storage system's main busbar, stopping its charging or discharging, thereby precisely isolating the battery cluster.

[0037] In the above scheme, the specific details of step S4 are as follows: Specifically, step S4 aims to precisely and dynamically adjust the total operating power of the energy storage system and establish a sequential, iterative offline balancing mechanism across multiple energy storage battery clusters. This step is crucial for achieving the core technical benefits of this invention, ensuring stable system operation and a constant power factor for the remaining battery clusters after a single battery cluster goes offline.

[0038] After the first energy storage battery cluster is successfully disconnected in step S3, The energy management system immediately executes this power adjustment step. First, The energy management system updates its internal record of the number of current online energy storage battery clusters, i.e. The value of is reduced by one. Then, The energy management system calculates the new system target operating power according to the following formula : ; Where, The system is disconnected After the battery cluster is protected, the power to be run should be: is the initial total power of the energy storage system; is the total number of battery clusters initially in the energy storage system; The number of battery clusters that have triggered protection and been disconnected.

[0039] After the calculation is completed, The energy management system will The value is encapsulated into a power limit instruction. This instruction is sent to the currently working power module (i.e. charging module or discharging module) through the preset communication interface or control line. After receiving this instruction, the power module uses it as the new power set point and adjusts its own energy conversion to reduce the total charging or discharging power of the energy storage system to The direct technical effect of this adjustment is that the charging or discharging current applied to each remaining online battery cluster is consistent with the current borne by each battery cluster in the initial state, so that its charging or discharging rate remains unchanged, avoiding the current shock caused by the reduction in the number of online clusters.

[0040] The sequence from status reporting to disconnection and then power adjustment is not a one-time action. After continuing to run, The energy management system continues to perform the monitoring of step S2. When the subsequent second energy storage battery cluster reaches its protection threshold, the above sequence will be triggered again, and the total system power will be reduced again based on the The value is further lowered. This process repeats, sequentially applying to each energy storage battery cluster until the last online energy storage battery cluster reaches its protection threshold and is disconnected. At this point, all energy storage battery clusters have reached the preset charge or discharge cutoff state, achieving a high degree of charge balance across the entire parallel system.

[0041] In the above scheme, the specific scheme details of step S5 are as follows: Specifically, step S5 aims to establish a closed-loop feedback verification mechanism for the control instructions issued in steps S3 and S4 to confirm that both the physical isolation action and the power adjustment action are accurately executed, thereby ensuring the reliability of the entire control strategy.

[0042] This step is not executed after the entire balancing process is completed, but is an accompanying inspection action that is immediately activated after each instruction of step S3 or S4 is issued. The energy management system initiates a continuous, periodic scanning and inspection program to monitor the results of instruction execution.

[0043] In a specific embodiment, to check whether the power off instruction in step S3 is executed, The energy management system monitors a status feedback signal associated with the power switch of the disconnected battery cluster. This feedback signal can come from the auxiliary contacts of the power switch itself. When the main contacts of the power switch are successfully opened, the state of its mechanically linked auxiliary contacts is reversed (for example, from closed to open). The energy management system reads this level change through one of its digital input ports, thereby confirming that the physical isolation action has been completed.

[0044] In another embodiment, to check whether the power limit instruction of step S4 is executed, The energy management system will make a reverse query to the charging module or the discharging module. After the power limit instruction, The energy management system will send a query message to the power module through the communication bus to read the current actual operating power. The power module will reply with its current actual power value. Compare it to the instruction value If the difference between the two is within the preset error range, it is confirmed that the power adjustment command has been successfully executed. This cyclic scanning test is carried out until all commands are confirmed to be executed, or an alarm is triggered if no correct feedback is received within the timeout period.

Claims

1. A control method for solving the uneven charge of parallel energy storage systems, characterized in that: The following steps are involved: S1. Performing a power-on self-test on the multiple energy storage battery clusters to determine the number of energy storage battery clusters online in real time, and performing automatic addressing and initial setting of system operating power accordingly; S2. When the first energy storage battery cluster triggers overcharge or over-discharge protection, the BMS battery management system of the first energy storage battery cluster reports its status information to the EMS energy management system; S3. After receiving the status information, the EMS energy management system issues a power disconnection instruction to disconnect the first energy storage battery cluster from the energy storage system; S4, the EMS energy management system sends a power limit instruction to the charging module or the discharging module to adjust the operating power of the energy storage system, and then returns to step S2 until all energy storage battery clusters reach the preset charging or discharging cut-off state; S5. Finally, a cyclic scanning test is performed to confirm that the power off instruction and the power limit instruction are executed.

2. A control method for solving uneven parallel charge of an energy storage system according to claim 1, characterized in that: In step S1, the power-on self-test, automatic addressing and initial setting respectively include the following steps: Power-on self-test: The BMS battery management system of each energy storage battery cluster performs self-test; Automatic addressing: When there are energy storage battery clusters that fail self-test, the EMS energy management system will re-address the remaining energy storage battery clusters that pass self-test; Initial setting: The EMS energy management system adjusts the system operating power according to the number of real-time online energy storage battery clusters.

3. A control method for solving uneven parallel charge of energy storage systems according to claim 2, characterized in that: After re-addressing the remaining energy storage battery clusters that have passed the self-test, it is necessary to re-check the number of the energy storage battery clusters that have passed the self-test to confirm that no energy storage battery cluster is omitted during the automatic addressing process.

4. A control method for solving uneven charge in parallel energy storage systems according to claim 1, characterized in that: In step S2, the status information includes: Overcharge protection status information, corresponding to the charging status; Over-discharge protection status information corresponds to the discharge status.

5. A control method for solving uneven parallel charge of energy storage systems according to claim 1, characterized in that: In step S3, the EMS energy management system sends the power disconnection instruction through the I / O interface and dry contact signal.

6. A control method for solving uneven charge in parallel energy storage systems according to claim 1, characterized in that: In step S4, the output power limited by the power limit instruction , which is calculated as follows: ; Where, The system is disconnected After the battery cluster is protected, the power to be run should be: is the initial total power of the energy storage system; is the total number of battery clusters initially in the energy storage system; The number of battery clusters that have triggered protection and been disconnected.

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