Control method suitable for energy storage multi-cluster dynamic switching parallel operation

Abstract

The invention discloses a control method suitable for energy storage multi-cluster dynamic switching parallel operation. The control method comprises a dynamic switching-out strategy and a dynamic switching-in strategy. The dynamic switching-out strategy is that when a plurality of battery clusters are used in parallel, the BMS calculates and reports the maximum allowable service power of the system; when a certain battery cluster breaks down, the BMS judges whether the battery cluster needs to be cut out of the system or not; after the fault cluster is cut out, the system gradually increases the overall allowable charging and discharging power to a normal level according to a preset power recovery proportion; according to the dynamic merging strategy, the battery clusters after fault recovery adjust voltage matching through DCDC boost / buck, or the merging time is directly judged according to the voltage difference value. By implementing the dynamic switching-out strategy, quick response can be achieved when the battery cluster breaks down, stable operation of other parts of the system is ensured, and the overall charging and discharging power of the system is gradually recovered according to the preset power recovery proportion. And meanwhile, the dynamic merging strategy ensures that the battery cluster after failure recovery can be efficiently and safely merged into the system again.

Description

Technical Field

[0001] The present invention belongs to the field of energy storage and management, and relates to a control method applicable to the dynamic switching and parallel operation of multiple clusters for energy storage. Background Art

[0002] With the rapid development of new energy technologies and the increasing demand for energy storage in the power grid, energy storage systems, as an important means to regulate the power grid's supply-demand balance and optimize resource allocation, have been widely applied in multiple fields such as industrial and commercial energy storage, large-scale energy storage, and combined heat and power energy storage for peak shaving. In these energy storage systems, in order to achieve efficient and stable energy storage and release, containerized energy storage units are usually adopted, which contain one or more energy storage stacks composed of battery clusters. Each battery cluster is formed by connecting multiple battery packs in series, and a plurality of battery clusters are connected in parallel to form an energy storage stack to meet the energy storage capacity and power requirements of the system.

[0003] In the existing energy storage system architecture, each cluster of batteries is usually controlled by a main board of a battery management system (BMS), which is responsible for monitoring key parameters such as the voltage, current, and temperature of the battery cluster, and reporting the battery information of this cluster to the energy management system (EMS) or the display. To improve the reliability and safety of the system, BMS manufacturers often design the charging and discharging control of multiple battery clusters (i.e., a stack) as a whole system during design. When any cluster of batteries in the stack fails, in order to avoid the spread of the fault and ensure the overall safety of the system, the entire stack will be required to stop charging and discharging, that is, to perform a high-voltage disconnection operation.

[0004] Although this design ensures the safety of the system to a certain extent, it also brings significant drawbacks. Firstly, it limits the full play of the system performance. When only one or a few clusters of batteries in the stack reach the full or empty state, the entire stack needs to stop charging and discharging, resulting in the inability of the remaining normally operating battery clusters to continue participating in the energy storage process, thus causing waste of system configuration. Secondly, for manufacturers relying on energy storage systems for peak shaving and valley filling, it seriously affects the realization of their economic benefits because during peak shaving and valley filling, the energy storage system needs to perform frequent charging and discharging operations, and once a cluster of batteries fails, the entire system has to stop working, thereby reducing the utilization rate and economic benefits of the energy storage system.

[0005] Therefore, in view of the above problems existing in the control of multiple clusters in a single stack in the existing energy storage system, it is necessary to propose a new switching control strategy to achieve real-time monitoring, early warning, and disconnection of the faulty cluster, while ensuring the continuous operation of other normally operating battery clusters and the overall performance of the system. Summary of the Invention

[0006] The object of the present invention is to solve the problem in the prior art that since the entire system needs to reduce power or stop working following a fault cluster, the remaining normally operating battery clusters cannot continue to exert their due energy storage and power supply capabilities, thereby restricting the overall performance of the system, and to provide a control method applicable to dynamic switching and parallel operation of multiple energy storage clusters.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A control method applicable to dynamic switching and parallel operation of multiple energy storage clusters, including a dynamic cut-out strategy and a dynamic connection strategy;

[0009] The dynamic cut-out strategy includes:

[0010] In an energy storage system, when multiple battery clusters are used in parallel, the maximum allowable power of the system calculated and reported by the BMS is the minimum allowable power of the multiple battery clusters multiplied by the number of battery clusters;

[0011] When a certain battery cluster fails, the BMS determines whether to cut out the battery cluster from the system by comparing the remaining power after power reduction with the overall system performance requirements; after the faulty cluster is cut out, the system gradually increases the overall allowable charge and discharge power to the normal level according to a preset power recovery ratio;

[0012] The dynamic connection strategy includes:

[0013] The battery cluster after fault recovery first boosts or buck-boosts the voltage to the same as the bus voltage through a DCDC and then connects to the system, and the DCDC reduces the pressure difference between the two parties at a preset rate until it stops working;

[0014] Or: for the battery cluster after fault recovery, the BMS judges the voltage difference between it and the bus voltage. If the difference is within the preset threshold, it directly connects to the system. If the difference exceeds the threshold, it waits for other non-faulty clusters to adjust the bus voltage to be close to the voltage of the faulty cluster and then connects;

[0015] When the system is initially powered on at high voltage, if a charging instruction is received, the BMS controls the battery clusters that meet the conditions to be powered on at high voltage with the battery cluster with the lowest total voltage as the reference within a preset voltage range; if no charging instruction is received, the high-voltage operation is performed with the battery cluster with the highest total voltage as the reference.

[0016] In the energy storage system, when multiple battery clusters are used in parallel, the maximum allowable power of the system calculated and reported by the BMS is the minimum allowable power of the multiple battery clusters multiplied by the number of battery clusters; specifically:

[0017] In an energy storage system where multiple battery clusters are used in parallel, the BMS selects the minimum value from the actual available powers of all battery clusters as the common allowable power of all battery clusters under the current system;

[0018] The BMS multiplies the selected minimum allowable power consumption by the number of battery clusters to calculate the maximum allowable power consumption of the system in the current state;

[0019] The BMS reports the calculated maximum allowable power consumption of the system to the upper management system or monitoring center of the energy storage system for formulating charge and discharge plans and performing power scheduling operations based on this power value;

[0020] The BMS can update the allowable power consumption of each battery cluster in real time or periodically, and recalculate the maximum allowable power consumption of the system according to the updated power value to adapt to the dynamically changing operating state of the energy storage system.

[0021] In the dynamic disconnection strategy, when a certain battery cluster fails, specifically: when it is detected that a certain battery cluster needs to reduce power due to a failure, the BMS calculates the amount of power reduction required for this cluster. If reducing the power to below a certain threshold will affect the overall performance of the system, then this cluster is directly disconnected from the system.

[0022] In the dynamic disconnection strategy, when a certain battery cluster fails:

[0023] When the BMS detects abnormal parameters of a certain battery cluster, it comprehensively analyzes the data and compares it with historical data to judge the type and severity of the failure;

[0024] Power reduction calculation and decision-making: The BMS calculates the amount of power that needs to be reduced based on the current state, failure type, and remaining capacity of the battery cluster; it evaluates whether reducing the power of this battery cluster to below a certain threshold will have a significant impact on the overall performance of the system, and the threshold is set according to the lowest requirements or performance standards of the system design.

[0025] If the BMS determines that reducing the power to below the threshold will seriously affect the overall performance of the system, it immediately disconnects this battery cluster from the system; after disconnecting the faulty battery cluster, the BMS recalculates the maximum allowable power consumption of the system and adjusts the charge and discharge strategies of other battery clusters.

[0026] In the dynamic disconnection strategy, when a certain battery cluster fails, specifically: when a certain battery cluster has a fault that requires high voltage to be removed, the BMS first controls the overall charge and discharge power according to the operating conditions of the system to reduce the current, and then safely disconnects the faulty cluster.

[0027] In the dynamic disconnection strategy, when a certain battery cluster fails:

[0028] After confirming the fault, the BMS evaluates the operating conditions of the current system, including the charge and discharge state of the system, load demand, and parameters of other battery clusters;

[0029] The BMS controls the charging and discharging power of the entire energy storage system, reduces the charging current, decreases the discharging power, or adjusts the power output strategy of the system;

[0030] Safe disconnection of the faulty battery cluster:

[0031] Preparation for pre-disconnection. After reducing the overall charging and discharging power, the BMS adjusts the control logic of the system to prepare for disconnecting the faulty battery cluster, ensuring that the disconnection process does not cause additional impacts on other battery clusters or the overall system;

[0032] Safe disconnection operation. The BMS performs the safe disconnection operation and uses a switching element to disconnect the faulty battery cluster from the high-voltage system;

[0033] System adjustment after disconnection. After the faulty battery cluster is disconnected, the BMS re-evaluates the system status and adjusts the charging and discharging strategies of other battery clusters.

[0034] Before the BMS performs the safe disconnection operation, it also conducts isolation verification of the faulty battery cluster to ensure that the electrical connection between the faulty battery cluster and the high-voltage system has been completely disconnected, avoiding the risk of electric arc or short circuit during the disconnection process.

[0035] In the described dynamic connection strategy, after the battery cluster recovers from the fault, it is first boosted or bucked by the DCDC to the same voltage as the bus voltage and then connected to the system. The DCDC reduces the voltage difference between the two sides at a preset rate until it stops working; specifically:

[0036] Voltage detection. The system first detects the voltage of the battery cluster after fault recovery and the current bus voltage;

[0037] Selection of DCDC converter. According to the comparison result of the battery cluster voltage and the bus voltage, the appropriate type of DCDC converter is selected. If the battery cluster voltage is lower than the bus voltage, a boost-type DCDC converter is selected; if the battery cluster voltage is higher than the bus voltage, a buck-type DCDC converter is selected;

[0038] Voltage conversion. The voltage of the battery cluster is boosted or bucked by the selected DCDC converter until the battery cluster voltage matches the bus voltage. During the boost process, the switching element inside the DCDC converter periodically conducts and cuts off. The inductor stores electrical energy when the switching element conducts and releases the electrical energy to supply power to the bus when the switching element cuts off, and the boost is achieved through the freewheeling of the diode. The buck process performs the opposite operation;

[0039] Connection to the system. When the battery cluster voltage is the same as the bus voltage, the system controls the corresponding switch or relay to connect the battery cluster to the system and starts the normal charging and discharging process;

[0040] Differential pressure detection and adjustment: After the battery cluster is incorporated into the system, the system continuously detects the differential pressure between the battery cluster and the bus. If a differential pressure is detected, the DCDC converter is controlled to gradually adjust its output voltage at a preset rate. The output voltage is changed by adjusting the duty cycle of the switching element inside the DCDC converter, thereby reducing the differential pressure between the two sides.

[0041] Stop working: When the differential pressure is reduced below the preset threshold, the system controls the DCDC converter to stop working. At this time, the switching element inside the DCDC converter no longer conducts and cuts off, and the circuit enters a stable state.

[0042] In the described dynamic incorporation strategy, for the battery cluster after fault recovery, the BMS judges the voltage difference between it and the bus voltage. If the difference is within the preset threshold, it is directly incorporated into the system. If the difference exceeds the threshold, it waits for other non-fault clusters to adjust the bus voltage to be close to the voltage of the fault cluster before incorporation; specifically:

[0043] Voltage detection: The BMS detects the voltage of the battery cluster after fault recovery and the current bus voltage.

[0044] Voltage difference calculation and judgment: The BMS calculates the difference between the battery cluster voltage and the bus voltage, and compares this difference with the preset threshold.

[0045] If the voltage difference is within the preset threshold, for the step of directly incorporating into the system, the BMS controls the corresponding switch or relay to directly incorporate the battery cluster into the system, and continuously monitors the charge and discharge states of the battery cluster and the system to ensure the stable operation of the system.

[0046] If the voltage difference exceeds the preset threshold, wait for voltage adjustment before incorporation. The BMS does not incorporate the battery cluster into the system temporarily and waits for other non-fault clusters to adjust the bus voltage to be close to the voltage of the battery cluster after fault recovery; during the waiting period, the BMS adjusts the bus voltage by adjusting the charge and discharge power of other non-fault clusters; the BMS re-detects the difference between the battery cluster voltage and the bus voltage. If the voltage difference is reduced to within the preset threshold, it is incorporated into the system; if the voltage difference still exceeds the preset threshold, continue to wait and adjust until the incorporation condition is met.

[0047] When the voltage difference meets the incorporation condition, the BMS controls the corresponding switch or relay to incorporate the battery cluster into the system, and continuously monitors the charge and discharge states of the battery cluster and the system to ensure the stable operation of the system.

[0048] When a certain battery cluster fails, the BMS records the relevant information of the faulty battery cluster, including the fault time, fault type, and parameters before the fault, and sends an alarm message to the operator.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] In the control method applicable to the dynamic switching and parallel operation of multiple energy storage clusters in the present invention, through the dynamic disconnection strategy, when a certain battery cluster fails, the BMS can quickly judge and disconnect the faulty battery cluster to prevent the spread of the fault and ensure the normal operation of the rest of the system. At the same time, the system can gradually increase the overall allowable charge-discharge power to the normal level according to the preset power recovery ratio, reducing the impact of the fault on the overall performance of the system.

[0051] In the dynamic disconnection strategy, the maximum allowable power of the system calculated and reported by the BMS takes into account the minimum allowable power among multiple battery clusters, ensuring that the system will not exceed the power limit of any single battery cluster when used in parallel, thereby optimizing the energy distribution and extending the service life of the battery clusters.

[0052] In the dynamic connection strategy, the battery cluster after fault recovery can be boosted or bucked by DCDC to the same voltage as the bus voltage and then connected to the system, or directly connected according to the voltage difference, improving the flexibility and efficiency of the battery cluster recovery. At the same time, when the system is initially powered on at high voltage, the BMS can intelligently control the high-voltage connection sequence of the battery clusters according to the charging instruction and the battery cluster voltage situation to ensure the safe and stable startup of the system.

[0053] The control method in the present invention is applicable to the energy storage system with multiple clusters for dynamic switching and parallel operation, and can flexibly cope with systems of different scales and configurations. By dynamically adjusting the connection and disconnection of the battery clusters, the system can expand or reduce the capacity according to needs to meet the requirements of different application scenarios. Brief Description of the Drawings

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative efforts.

[0055] Figure 1 It is a schematic flowchart of a control method applicable to the dynamic switching and parallel operation of multiple energy storage clusters of the present invention. Detailed Embodiments

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0057] Accordingly, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0058] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0059] The present invention will be further described in detail below with reference to the accompanying drawings:

[0060] See Figure 1 , which is a schematic flowchart of a control method applicable to the dynamic switching and parallel operation of multiple clusters in energy storage, including a dynamic cut-out strategy and a dynamic connection strategy;

[0061] The dynamic cut-out strategy includes:

[0062] In an energy storage system, when multiple battery clusters are used in parallel, the maximum allowable power of the system calculated and reported by the BMS is the minimum allowable power of the multiple battery clusters multiplied by the number of battery clusters; specifically:

[0063] In an energy storage system where multiple battery clusters are used in parallel, the BMS selects the minimum value from the actual available powers of all battery clusters as the common allowable power of all battery clusters under the current system.

[0064] The BMS multiplies the selected minimum allowable power by the number of battery clusters to calculate the maximum allowable power of the system in the current state.

[0065] The BMS reports the calculated maximum allowable power of the system to the upper management system or monitoring center of the energy storage system for formulating charge and discharge plans and performing power scheduling operations based on this power value.

[0066] The BMS can update the allowable power of each battery cluster in real time or periodically and recalculate the maximum allowable power of the system based on the updated power value to adapt to the dynamically changing operating state of the energy storage system.

[0067] When a certain battery cluster fails, the BMS determines whether it is necessary to cut out the battery cluster from the system by comparing the remaining power after power reduction with the overall performance requirements of the system; after the faulty cluster is cut out, the overall allowable charge and discharge power of the system gradually increases to the normal level according to a preset power recovery ratio.

[0068] When it is detected that a certain battery cluster fails and power reduction is required, the BMS calculates the amount of power reduction required for this cluster. If reducing the power to below a certain threshold will affect the overall system performance, the cluster is directly cut out of the system. Specifically:

[0069] When the BMS detects abnormal parameters of a certain battery cluster, it comprehensively analyzes the data and compares it with historical data to judge the type and severity of the fault;

[0070] Power reduction calculation and decision-making: The BMS calculates the amount of power that needs to be reduced based on the current state, fault type, and remaining capacity of the battery cluster; it evaluates whether reducing the power of this battery cluster to below a certain threshold will have a significant impact on the overall system performance, and the threshold is set according to the minimum requirements or performance standards of the system design;

[0071] If the BMS determines that reducing the power to below the threshold will seriously affect the overall system performance, it immediately cuts out this battery cluster from the system; after cutting out the faulty battery cluster, the BMS recalculates the maximum allowable power of the system and adjusts the charge and discharge strategies of other battery clusters.

[0072] When a certain battery cluster has a fault that requires high voltage disconnection, the BMS first controls the overall charge and discharge power according to the system operating conditions to reduce the current, and then safely cuts out the faulty cluster. Specifically:

[0073] After confirming the fault, the BMS evaluates the current operating conditions of the system, including the charge and discharge status of the system, load demand, and parameters of other battery clusters;

[0074] The BMS controls the charge and discharge power of the entire energy storage system, reduces the charging current, decreases the discharge power, or adjusts the power output strategy of the system;

[0075] Safe cut-out of the faulty battery cluster:

[0076] Preparation for pre-cut-out: After reducing the overall charge and discharge power, the BMS adjusts the control logic of the system to prepare for cutting out the faulty battery cluster, ensuring that the cut-out process does not cause additional impact on other battery clusters or the overall system;

[0077] Safe cut-out operation: The BMS performs a safe cut-out operation, using a switching element to disconnect the faulty battery cluster from the high-voltage system;

[0078] System adjustment after cut-out: After the faulty battery cluster is cut out, the BMS re-evaluates the system status and adjusts the charge and discharge strategies of other battery clusters.

[0079] Before the BMS performs the safe cut-out operation, it also conducts isolation verification of the faulty battery cluster to ensure that the electrical connection between the faulty battery cluster and the high-voltage system has been completely disconnected, avoiding the risk of electric arc or short circuit during the cut-out process.

[0080] The dynamic incorporation strategy includes:

[0081] After the battery cluster recovers from a fault, it is first boosted or bucked by a DCDC to the same voltage as the bus voltage and then incorporated into the system. The DCDC reduces the voltage difference between the two sides at a preset rate until it stops working. Specifically:

[0082] Voltage detection. The system first detects the voltage of the battery cluster after fault recovery and the current bus voltage.

[0083] DCDC converter selection. According to the comparison result of the battery cluster voltage and the bus voltage, the appropriate type of DCDC converter is selected. If the battery cluster voltage is lower than the bus voltage, a boost-type DCDC converter is selected; if the battery cluster voltage is higher than the bus voltage, a buck-type DCDC converter is selected.

[0084] Voltage conversion. The voltage of the battery cluster is boosted or bucked by the selected DCDC converter until the battery cluster voltage matches the bus voltage. During the boost process, the switching element inside the DCDC converter is periodically turned on and off. The inductor stores electrical energy when the switching element is on and releases the electrical energy to supply power to the bus when the switching element is off, and the boost is achieved through the freewheeling of the diode. The buck process performs the opposite operation.

[0085] Incorporation into the system. When the battery cluster voltage is the same as the bus voltage, the system controls the corresponding switch or relay to incorporate the battery cluster into the system and starts the normal charge and discharge process.

[0086] Voltage difference detection and adjustment. After the battery cluster is incorporated into the system, the system continuously detects the voltage difference between the battery cluster and the bus. If a voltage difference is detected, the system controls the DCDC converter to gradually adjust its output voltage at a preset rate by adjusting the duty cycle of the switching element inside the DCDC converter to change the output voltage, thereby reducing the voltage difference between the two sides.

[0087] Stop working. When the voltage difference is reduced below the preset threshold, the system controls the DCDC converter to stop working. At this time, the switching element inside the DCDC converter no longer turns on and off, and the circuit enters a stable state.

[0088] Or: For the battery cluster after fault recovery, the BMS judges the voltage difference between it and the bus voltage. If the difference is within the preset threshold, it is directly incorporated into the system. If the difference exceeds the threshold, it waits for other non-faulty clusters to adjust the bus voltage to be close to the voltage of the faulty cluster and then incorporates it. Specifically:

[0089] Voltage detection. The BMS detects the voltage of the battery cluster after fault recovery and the current bus voltage.

[0090] Voltage difference calculation and judgment. The BMS calculates the voltage difference between the battery cluster voltage and the bus voltage and compares this difference with the preset threshold.

[0091] If the voltage difference is within the preset threshold, directly proceed to the step of integrating into the system. The BMS controls the corresponding switches or relays to directly integrate the battery cluster into the system and continuously monitors the charging and discharging states of the battery cluster and the system to ensure the stable operation of the system;

[0092] If the voltage difference exceeds the preset threshold, wait until the voltage is adjusted before integrating. The BMS does not integrate the battery cluster into the system temporarily and waits for other non-faulty clusters to adjust the bus voltage to be close to the voltage of the battery cluster after fault recovery; during the waiting period, the BMS adjusts the bus voltage by adjusting the charging and discharging power of other non-faulty clusters; the BMS re-detects the difference between the battery cluster voltage and the bus voltage. If the voltage difference decreases to within the preset threshold, integrate it into the system; if the voltage difference still exceeds the preset threshold, continue to wait and adjust until the integration condition is met;

[0093] When the voltage difference meets the integration condition, the BMS controls the corresponding switches or relays to integrate the battery cluster into the system and continuously monitors the charging and discharging states of the battery cluster and the system to ensure the stable operation of the system.

[0094] When the system initially powers on to high voltage, if a charging instruction is received, the BMS uses the battery cluster with the lowest total voltage as a reference and controls the battery clusters that meet the conditions to power on to high voltage within a preset voltage range; if no charging instruction is received, the BMS performs the high-voltage operation with the battery cluster with the highest total voltage as a reference.

[0095] When a certain battery cluster fails, the BMS records the relevant information of the faulty battery cluster, including the fault time, fault type, and parameters before the fault, and sends an alarm message to the operator.

[0096] A control method for dynamic switching and parallel operation of multiple energy storage clusters proposed by the present invention significantly improves the comprehensive performance of the energy storage system. By implementing the dynamic cut-out strategy, this method can quickly respond when a battery cluster fails, ensure the stable operation of the rest of the system, and gradually restore the overall charging and discharging power of the system according to the preset power recovery ratio. At the same time, the dynamic integration strategy ensures that the battery cluster after fault recovery can be efficiently and safely re-integrated into the system. Whether it is through DCDC step-up / step-down to adjust the voltage matching or directly judging the integration timing based on the voltage difference, it greatly enhances the flexibility and recovery efficiency of the system. In addition, this method also supports intelligent control when the system initially powers on to high voltage, optimizing the high-voltage sequence according to the charging instruction and the battery cluster voltage situation. These characteristics work together on the energy storage system, not only improving the reliability and stability of the system, but also optimizing the energy management, enhancing the scalability and flexibility of the system, and significantly improving the intelligent management level of the system, laying a solid foundation for the safe and efficient operation of the energy storage system.

[0097] Embodiment

[0098] When 6 clusters are connected in parallel for use, the maximum allowable power of the system reported by the BMS = the minimum allowable power of the 6 clusters * 6. Such a design ensures that the system will not experience overcharging or over-discharging

[0099] When a fault occurs during the operation of 6 clusters, but the fault only reduces the power and does not require high-voltage disconnection, the BMS needs to determine the power reduction amount required for this cluster. If the power reduction amount meets the following formula, high-voltage disconnection is directly performed: (6 - 1) * 100 = 6 * P. It is deduced that if the power of this cluster drops to 80%, this cluster is directly cut out of the system because if this cluster is not cut out of the system, the maximum power of the 6 clusters running is only 6 * Pmin * 0.8, which is less than 5 * Pmin * 100% when 5 clusters are running

[0100] When any cluster experiences a fault that requires high-voltage disconnection during the operation of 6 clusters, the BMS should control this faulty cluster to be cut out of the system. It should be noted here that the cluster is not directly cut out after the fault occurs. The current operating conditions need to be considered. If it is in a static state at this time, the BMS can directly cut out this cluster. If the system is in the process of charging and discharging, that is, when there is a large current during charging and discharging, it cannot be directly cut out because the load disconnection of the relay will cause adhesion, which will have the opposite effect. Therefore, at this time, the BMS needs to first control the overall allowable charging and discharging power and control the charging and discharging current of the system at a relatively low level. At this time, load-disconnecting the relay will not cause adhesion

[0101] When a fault occurs in the system, power reduction processing needs to be carried out first. After the current stabilizes, the relay is disconnected. After the faulty cluster is cut out of the system, the system then restores the overall allowable charging and discharging power of the system to the normal level according to a certain power recovery ratio

[0102] Dynamic connection strategy:

[0103] Continuing from the above conditions, after the faulty cluster is cut out of the system and the fault is restored, two solutions are proposed for selection as to whether it is allowed to be connected to the system:

[0104] Solution 1: The faulty cluster first connects to the DCDC to boost or buck the voltage to be the same as the bus voltage at this time, and then connects to other clusters. After the faulty cluster is connected to the system, the DCDC reduces the voltage difference between the two parties at a rate of 1V / 3S according to the voltage difference between the two parties. When the time is up, the DCDC stops working. The advantage of this strategy is that when the faulty cluster is restored, it can be immediately connected to the system for use regardless of the voltage difference between the faulty cluster and the bus at this time. However, there are also some disadvantages, that is, the control strategy will be much more complex, and at the same time, it is required to be equipped with a DCDC in a stack specifically for the faulty cluster to connect to the system

[0105] To address the above drawbacks and save costs simultaneously, Solution 2 is proposed.

[0106] Solution 2: After the fault cluster recovers, the BMS needs to determine the voltage difference between the fault cluster and the bus voltage at this time. If the threshold value V between the two is ≤ 10V (this value needs to be obtained by combining the relay manual and system parameter configuration), the fault cluster can be directly incorporated into the system, and the inrush current at this time will not cause the relay to stick. When the voltage difference V between the fault cluster and the bus voltage is > 10V, the fault cluster needs to wait for other non-fault clusters to charge or discharge to make the bus voltage close to the voltage of the fault cluster, and then be incorporated into the system. Compared with Solution 1, the BMS control strategy of this solution is simple and does not require an additional DCDC in each stack for incorporation, saving costs. However, the disadvantage is that the fault cluster needs to wait for the voltage difference between the bus voltage and the fault cluster to be within a reasonable range before it is allowed to be incorporated when the fault cluster recovers.

[0107] When the system initially powers on to high voltage, that is, when all clusters have not powered on to high voltage, the voltage difference between clusters is large and all clusters have no faults prohibiting powering on to high voltage. How does the BMS perform the high-voltage operation? This patent states that when a charging instruction is received before powering on to high voltage, the BMS needs to use the cluster with the lowest total voltage as a reference and control the eligible high-voltage clusters to power on to high voltage within a range of 10V. If no high-voltage instruction is received, the BMS needs to use the highest total voltage as a reference and control the eligible clusters to power on to high voltage within a range of 10V. This is because when there is a charging signal, it is highly likely that the system is about to charge. Therefore, the clusters with lower total voltage are incorporated into the system first, and charging is used to increase the bus voltage to be the same as the voltage of other unconnected clusters, and then parallel operation is achieved. If no charging instruction is received before powering on to high voltage, the clusters with higher total voltage should be used as a reference because it is highly likely that the system will discharge. By discharging, the bus voltage of the system is reduced to be the same as the voltage of the unincorporated clusters, and then parallel operation is achieved.

[0108] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A control method applicable to the parallel operation of multiple clusters of energy storage with dynamic switching, characterized in that, It includes a dynamic cut-out strategy and a dynamic incorporation strategy; The dynamic cut-out strategy includes: In an energy storage system, when multiple battery clusters are used in parallel, the maximum allowable power of the system calculated and reported by the BMS is the minimum allowable power of the multiple battery clusters multiplied by the number of battery clusters; When a certain battery cluster fails, the BMS determines whether to cut out the battery cluster from the system by comparing the remaining power after power reduction with the overall system performance requirements; after the faulty cluster is cut out, the system gradually increases the overall allowable charge and discharge power to the normal level according to a preset power recovery ratio; The dynamic incorporation strategy includes: The battery cluster after fault recovery is first boosted or bucked by DCDC to the same voltage as the bus voltage and then incorporated into the system. DCDC reduces the pressure difference between the two parties at a preset rate until it stops working; Or: for the battery cluster after fault recovery, the BMS judges the voltage difference between it and the bus voltage. If the difference is within the preset threshold, it is directly incorporated into the system. If the difference exceeds the threshold, it waits for other non-faulty clusters to adjust the bus voltage to be close to the voltage of the faulty cluster before incorporating; When the system is initially powered on at high voltage, if a charging instruction is received, the BMS uses the battery cluster with the lowest total voltage as the reference and controls the battery clusters that meet the conditions to be powered on at high voltage within a preset voltage range; if no charging instruction is received, the high-voltage operation is performed with the battery cluster with the highest total voltage as the reference.

2. The control method for multi-cluster dynamic switching and parallel operation applicable to energy storage as claimed in claim 1, wherein In the energy storage system, when multiple battery clusters are used in parallel, the maximum allowable power of the system calculated and reported by the BMS is the minimum allowable power of the multiple battery clusters multiplied by the number of battery clusters; specifically: In an energy storage system where multiple battery clusters are used in parallel, the BMS selects the minimum value from the actual available powers of all battery clusters as the common allowable power of all battery clusters under the current system; The BMS multiplies the selected minimum allowable power by the number of battery clusters to calculate the maximum allowable power of the system in the current state; The BMS reports the calculated maximum allowable power of the system to the upper management system or monitoring center of the energy storage system for formulating charge and discharge plans and performing power scheduling operations based on this power value; The BMS can update the allowable power of each battery cluster in real time or regularly and recalculate the maximum allowable power of the system according to the updated power value to adapt to the dynamically changing operating state of the energy storage system.

3. A control method applicable to parallel operation of multiple clusters for energy storage dynamic switching, as claimed in claim 1, characterized in that In the dynamic cut-out strategy, when a certain battery cluster fails, specifically: when it is detected that a certain battery cluster needs to reduce power due to a failure, the BMS calculates the amount of power reduction required for this cluster. If reducing the power to below a certain threshold will affect the overall system performance, the cluster is directly cut out of the system.

4. A control method applicable to the parallel operation of multiple clusters of energy storage for dynamic switching, as claimed in claim 3, characterized in that, In the dynamic cut-out strategy, when a certain battery cluster fails: When the BMS detects abnormal parameters of a certain battery cluster, it comprehensively analyzes the data and compares it with historical data to judge the type and severity of the fault; Power reduction calculation and decision-making. The BMS calculates the amount of power that needs to be reduced based on the current state, fault type, and remaining capacity of the battery cluster; it evaluates whether reducing the power of this battery cluster to below a certain threshold will have a significant impact on the overall system performance, and the threshold is set according to the minimum requirements or performance standards of the system design. If the BMS determines that reducing the power below the threshold will seriously affect the overall system performance, it immediately cuts out the battery cluster from the system; after cutting out the faulty battery cluster, the BMS recalculates the maximum allowable power of the system and adjusts the charge and discharge strategies of other battery clusters.

5. A control method for multi-cluster dynamic switching and parallel operation applicable to energy storage, characterized in that, When a certain battery cluster fails in the dynamic cut-out strategy, specifically: when a certain battery cluster has a fault that requires discharging high voltage, the BMS first controls the overall charge and discharge power according to the system operating conditions to reduce the current, and then safely cuts out the faulty cluster.

6. The control method for multi-cluster dynamic switching and parallel operation applicable to energy storage as described in claim 5, characterized in that, When a certain battery cluster fails in the dynamic cut-out strategy: After confirming the fault, the BMS evaluates the current system operating conditions, including the charge and discharge state of the system, the load demand, and the parameters of other battery clusters; The BMS controls the charge and discharge power of the entire energy storage system, reduces the charging current, decreases the discharge power, or adjusts the power output strategy of the system; Safe cut-out of the faulty battery cluster: Pre-cut-out preparation, after reducing the overall charge and discharge power, the BMS adjusts the control logic of the system to prepare for cutting out the faulty battery cluster, ensuring that the cut-out process does not cause additional impacts on other battery clusters or the overall system; Safe cut-out operation, the BMS performs a safe cut-out operation and uses a switching element to disconnect the faulty battery cluster from the high-voltage system; System adjustment after cut-out, after the faulty battery cluster is cut out, the BMS re-evaluates the system state and adjusts the charge and discharge strategies of other battery clusters.

7. A control method for a multi-cluster dynamic switching parallel operation applicable to energy storage, as claimed in claim 6, wherein Before the BMS performs the safe cut-out operation, it also conducts isolation verification of the faulty battery cluster to ensure that the electrical connection between the faulty battery cluster and the high-voltage system has been completely disconnected, avoiding the risk of electric arc or short circuit during the cut-out process.

8. A control method for multi-cluster dynamic switching and parallel operation applicable to energy storage, characterized in that, In the dynamic connection-in strategy, after the battery cluster recovers from the fault, it is first boosted or bucked by the DCDC to the same voltage as the bus voltage and then connected into the system, and the DCDC reduces the pressure difference between the two sides at a preset rate until it stops working; specifically: Voltage detection, the system first detects the voltage of the battery cluster after fault recovery and the current bus voltage; DCDC converter selection, according to the comparison result of the battery cluster voltage and the bus voltage, select the appropriate type of DCDC converter. If the battery cluster voltage is lower than the bus voltage, select a boost-type DCDC converter; if the battery cluster voltage is higher than the bus voltage, select a buck-type DCDC converter; Voltage conversion, boost or buck the voltage of the battery cluster through the selected DCDC converter until the battery cluster voltage matches the bus voltage. During the boost process, the switching element inside the DCDC converter is periodically turned on and off, the inductor stores electrical energy when the switching element is on, releases electrical energy to supply power to the bus when the switching element is off, and realizes boosting through diode freewheeling. The buck process performs the opposite operation; Connect into the system, when the battery cluster voltage is the same as the bus voltage, the system controls the corresponding switch or relay to connect the battery cluster into the system and starts the normal charge and discharge process; Differential pressure detection and adjustment: After the battery cluster is incorporated into the system, the system continuously detects the differential pressure between the battery cluster and the bus. If a differential pressure is detected, the DCDC converter is controlled to gradually adjust its output voltage at a preset rate. The output voltage is changed by adjusting the duty cycle of the switching element inside the DCDC converter, thereby reducing the differential pressure between the two sides. Stop working: When the differential pressure is reduced below the preset threshold, the system controls the DCDC converter to stop working. At this time, the switching element inside the DCDC converter no longer conducts and cuts off, and the circuit enters a stable state.

9. The control method for multi-cluster dynamic switching and parallel operation applicable to energy storage according to claim 1, characterized in that In the described dynamic incorporation strategy, for the battery cluster after fault recovery, the BMS judges the voltage difference between it and the bus voltage. If the difference is within the preset threshold, it is directly incorporated into the system. If the difference exceeds the threshold, it waits for other non-faulty clusters to adjust the bus voltage to be close to the voltage of the faulty cluster before incorporation; specifically: Voltage detection: The BMS detects the voltage of the battery cluster after fault recovery and the current bus voltage. Voltage difference calculation and judgment: The BMS calculates the difference between the battery cluster voltage and the bus voltage, and compares this difference with the preset threshold. If the voltage difference is within the preset threshold, for the step of directly incorporating into the system, the BMS controls the corresponding switch or relay to directly incorporate the battery cluster into the system, and continuously monitors the charge and discharge states of the battery cluster and the system to ensure the stable operation of the system. If the voltage difference exceeds the preset threshold, wait to incorporate after adjusting the voltage: The BMS does not incorporate the battery cluster into the system temporarily and waits for other non-faulty clusters to adjust the bus voltage to be close to the voltage of the battery cluster after fault recovery; during the waiting period, the BMS adjusts the bus voltage by adjusting the charge and discharge power of other non-faulty clusters; the BMS re-detects the difference between the battery cluster voltage and the bus voltage. If the voltage difference is reduced within the preset threshold, it is incorporated into the system; if the voltage difference still exceeds the preset threshold, continue to wait and adjust until the incorporation condition is met. When the voltage difference meets the incorporation condition, the BMS controls the corresponding switch or relay to incorporate the battery cluster into the system, and continuously monitors the charge and discharge states of the battery cluster and the system to ensure the stable operation of the system.

10. A control method for multi-cluster dynamic switching and parallel operation applicable to energy storage, as described in claim 1, characterized in that, When a certain battery cluster fails, the BMS records the relevant information of the faulty battery cluster, including the fault time, fault type, and parameters before the fault, and sends an alarm message to the operator.

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