High-voltage cascaded energy storage system and control method thereof

Abstract

The application relates to the technical field of high-voltage energy storage, and discloses a high-voltage cascaded energy storage system and a control method thereof. The high-voltage cascaded energy storage system comprises a battery management system and an energy storage converter, the battery management system comprises a first-level BMS control module, a second-level BMS control module and a third-level BMS control module which are sequentially connected from bottom to top, the energy storage converter comprises a PCS master control module and a plurality of PCS power modules, the first-level BMS control module is in communication connection with the second-level BMS control module through a CAN bus, the second-level BMS control module is in communication connection with the third-level BMS control module through an optical fiber, the PCS master control module is in communication connection with the third-level BMS control module through an Ethernet and / or a CAN bus, the PCS master control module is in communication connection with the PCS power modules through an optical fiber, the PCS power modules are also connected with the second-level BMS control modules, and each PCS power module is connected with at least two second-level BMS control modules.

Description

Technical Field

[0001] This application relates to the field of communication technology for high-voltage cascaded energy storage systems, and more specifically, to a high-voltage cascaded energy storage system and its control method. Background Technology

[0002] As energy storage technology develops towards higher power and larger capacity, high-voltage cascaded energy storage direct-connection solutions are widely used in grid peak shaving, industrial and commercial energy storage, and microgrid power supply scenarios due to their advantages such as no need for step-up transformers, high energy conversion efficiency, and flexible capacity expansion. In high-voltage cascaded energy storage systems, the Battery Management System (BMS) and the Power Conversion System (PCS) are the core control units. The stability of communication between and within these two systems, as well as the rationality of control strategies, directly determine the operational safety, reliability, and battery life of the energy storage system.

[0003] Currently, the communication architecture of existing high-voltage cascaded energy storage systems has several shortcomings: First, the communication methods between different levels within the BMS are simplistic and lack redundancy, making them susceptible to high-voltage electromagnetic interference, which can lead to communication interruptions or data transmission errors. Second, the communication interfaces between the BMS and PCS are not standardized, resulting in low data exchange efficiency and an inability to achieve real-time synchronization of core parameters. Third, the communication within the PCS does not adequately consider high-voltage insulation requirements, posing safety hazards. Furthermore, in terms of control strategies, existing solutions' pre-charge control is not optimized for multi-cluster parallel battery scenarios, resulting in insufficient accuracy in inter-cluster voltage difference control and a high risk of inrush current damage to equipment. Battery balancing focuses only on a single dimension, offering limited improvement in consistency. Moreover, no targeted auxiliary control strategies have been designed for the environmental sensitivity of high-voltage cascaded systems, making them susceptible to long-term stable operation issues caused by abnormal temperature and humidity or condensation.

[0004] There is currently no effective solution to the aforementioned technical problems. Summary of the Invention

[0005] This application provides a high-voltage cascaded energy storage system and its control method to at least solve the technical problems of unstable communication and unreasonable control strategies in high-voltage cascaded energy storage systems, which lead to low control accuracy and efficiency, low safety, and affect battery life and overall operating efficiency of the energy storage system.

[0006] According to one aspect of the embodiments of this application, a high-voltage cascaded energy storage system is provided, including a battery management system and an energy storage converter. The battery management system includes a first-level BMS control module, a second-level BMS control module, and a third-level BMS control module connected sequentially from bottom to top. The energy storage converter includes a PCS master control module and multiple PCS power modules. The first-level BMS control module is communicatively connected to the second-level BMS control module via a CAN bus. The second-level BMS control module is communicatively connected to the third-level BMS control module via an optical fiber. The PCS master control module is communicatively connected to the third-level BMS control module via an Ethernet and / or CAN bus. The PCS master control module is communicatively connected to the PCS power modules via the optical fiber. The PCS power modules are also connected to the second-level BMS control modules. Each PCS power module is connected to at least two of the second-level BMS control modules.

[0007] Optionally, an optical converter and an optical conversion module are provided between the secondary BMS control module and the tertiary BMS control module. The tertiary BMS control module is connected to the optical converter via Ethernet and CAN bus respectively. The optical converter is connected to one end of the optical conversion module via optical fiber. The other end of the optical conversion module is connected to the secondary BMS control module via the CAN bus. The secondary BMS control module is also connected to the PCS power module via the CAN bus.

[0008] Optionally, the PCS master control module is also connected to the PCS power module via a dry contact, and the secondary BMS control module is connected in series to the controlled circuit of the PCS power module via a dry contact.

[0009] Optionally, the three-level BMS control module includes a data aggregation unit, wherein the data aggregation unit is configured as follows:

[0010] Receive single-cell cluster data from each of the secondary BMS control modules, and aggregate single-cell cluster data from multiple secondary BMS control modules corresponding to the same PCS power module;

[0011] The PCS master control module includes a power distribution unit, wherein the power distribution unit is configured as follows:

[0012] Based on the battery stack data of each of the three-level BMS control modules, the power of each battery stack is allocated, and / or, based on the aggregated data of the data aggregation unit and the single battery cluster data, the power of multiple battery clusters corresponding to the same PCS power module is allocated.

[0013] Optionally, the three-level BMS control module further includes a first fault handling unit, wherein the first fault handling unit is configured as follows:

[0014] Determine the fault level of multiple battery clusters corresponding to the same PCS power module, and determine the comprehensive fault level based on the fault level of each battery cluster;

[0015] The PCS master control module further includes a second fault handling unit, which is configured as follows:

[0016] Based on the comprehensive fault level and fault information of the fault clusters, fault handling is performed on multiple battery clusters.

[0017] Optionally, at least one of the multiple secondary BMS control modules connected to the same PCS power module is connected to the main battery cluster, and at least one of the multiple secondary BMS control modules is connected to the slave battery cluster; the main battery cluster includes a main cluster precharge contactor and a main cluster main DC contactor, and the slave battery cluster includes a slave cluster main DC contactor and a slave cluster circulating current contactor; the main cluster precharge contactor, the main cluster main DC contactor, the slave cluster main DC contactor, and the slave cluster circulating current contactor are respectively connected to the PCS master control module;

[0018] The PCS master control module includes a pre-charge control unit, which is configured to control the main cluster pre-charge contactor to close to pre-charge the main battery cluster, and control the main cluster main DC contactor according to the pre-charge result to control the operation of the main battery cluster; the pre-charge control unit is also configured to control the slave cluster main DC contactor and the slave cluster circulating current contactor based on the inter-cluster voltage difference between the main battery cluster and the slave battery cluster after the main battery cluster is powered on, so as to control the operation of the slave battery cluster.

[0019] Optionally, the three-level BMS control module further includes a differential pressure judgment unit, configured as follows:

[0020] If the inter-cluster pressure difference is less than or equal to the first pressure difference threshold, it is determined that the inter-cluster pressure difference is within the pressure difference safe range.

[0021] If the inter-cluster pressure difference is greater than the first pressure difference threshold and less than the second pressure difference threshold, it is determined that the inter-cluster pressure difference is in the pressure difference equilibrium range.

[0022] If the inter-cluster pressure difference is greater than or equal to the second pressure difference threshold, the inter-cluster pressure difference is determined to be in the pressure difference danger range.

[0023] The pre-charge control unit is configured to: control the main DC contactor of the slave cluster to close when the inter-cluster pressure difference is within the safe range of the pressure difference, so as to pre-charge the slave battery cluster; and control the circulating contactor of the slave cluster to close when the inter-cluster pressure difference is within the range of the pressure difference that can be balanced, so as to adjust the inter-cluster pressure difference.

[0024] Optionally, the PCS master control module further includes a balance control unit, wherein the balance control unit is configured as follows:

[0025] Based on the preset total output power of the energy storage system and the SOC deviation ratio of each battery stack, the inter-stack equalization adjustment is performed on multiple battery stacks.

[0026] Based on the active power of the PCS and the SOC deviation ratio of each phase battery cluster in the three-phase battery cluster, phase-to-phase equalization adjustment is performed on multiple battery stacks, wherein each phase battery cluster includes at least one of the PCS power modules.

[0027] The PCS master control module also includes an inter-stack equalization safety control unit, wherein the inter-stack equalization safety control unit is configured to: monitor the operating data of each battery stack during the inter-stack equalization adjustment process, and perform equalization safety control based on the operating data of the battery stack.

[0028] The secondary BMS control module is configured to monitor the operating data of each battery cluster during the process of inter-stack equalization and inter-phase equalization adjustment, and to perform equalization safety control based on the operating data of the battery cluster.

[0029] Optionally, the PCS master control module further includes an auxiliary control unit configured to adjust the environmental parameters of the energy storage system, wherein the environmental parameters include at least one of temperature, humidity and light intensity.

[0030] According to another aspect of the embodiments of this application, a control method for a high-voltage cascaded energy storage system is also provided, applied to the aforementioned high-voltage cascaded energy storage system, the method comprising:

[0031] In response to the control strategy of the secondary BMS control module, the operation of at least one battery pack is controlled by the primary BMS control module.

[0032] In response to the control strategy of the three-level BMS control module, the operation of at least one battery cluster is controlled by the two-level BMS control module.

[0033] In response to the control strategy of the PCS master control module, the operation of at least one battery stack is controlled by the three-level BMS control module, and multiple three-level BMS control modules are coordinated and controlled by the PCS master control module.

[0034] The PCS master control module coordinates the control of multiple secondary BMS control modules connected to the same PCS power module.

[0035] The high-voltage cascaded energy storage system and its control method provided in this application embodiment, by setting up a battery management system and an energy storage converter, wherein the battery management system includes a first-level BMS control module, a second-level BMS control module, and a third-level BMS control module connected sequentially from bottom to top, and the energy storage converter includes a PCS master control module and multiple PCS power modules, wherein the first-level BMS control module is communicatively connected to the second-level BMS control module via a CAN bus, the second-level BMS control module is communicatively connected to the third-level BMS control module via an optical fiber, and the PCS master control module is communicatively connected to the third-level BMS control module via an Ethernet and / or CAN bus, and the PCS master control module is communicatively connected to the third-level BMS control module via the optical fiber. The fiber optic cable is communicatively connected to the PCS power module, which is also connected to the secondary BMS control module. Each PCS power module is connected to at least two secondary BMS control modules. This hierarchical, distributed, and strongly electrically isolated communication connection architecture improves the communication reliability and stability of the energy storage system, while ensuring communication security and compatibility. Simultaneously, through the cooperation of the PCS master control module, PCS power modules, secondary BMS control modules, and tertiary BMS control modules, inter-pile and inter-cluster collaborative control can be achieved, improving control accuracy and efficiency, enhancing the safety of the energy storage system, extending battery life, and increasing the overall operating efficiency of the energy storage system. Attached Figure Description

[0036] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0037] Figure 1 This is a structural block diagram of a high-voltage cascaded energy storage system provided according to an embodiment of this application;

[0038] Figure 2 This is a schematic diagram of the high-voltage cascaded energy storage system provided according to an embodiment of this application;

[0039] Figure 3 This is another structural schematic diagram of a high-voltage cascaded energy storage system provided according to an embodiment of this application;

[0040] Figure 4 This is a schematic diagram of the power-on (including fault detection and pre-charge control) of a high-voltage cascaded energy storage system according to an embodiment of this application;

[0041] Figure 5 This is a flowchart of a control method for a high-voltage cascaded energy storage system provided according to an embodiment of this application. Detailed Implementation

[0042] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0043] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0044] According to an embodiment of this application, a method embodiment for communication of a high-voltage cascaded energy storage system is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0045] Figure 1 This is a structural block diagram of a high-voltage cascaded energy storage system provided according to an embodiment of this application. For example... Figure 1As shown in the figure, this application provides a high-voltage cascaded energy storage system, including a battery management system (BMS) and a power storage converter (PCS). The battery management system includes a first-level BMS control module (not shown), a second-level BMS control module 11, and a third-level BMS control module 12 connected sequentially from bottom to top. The power storage converter includes a PCS master control module 21 and multiple PCS power modules 22. The first-level BMS control module is communicatively connected to the second-level BMS control module 11 via a CAN bus. The second-level BMS control module 11 is communicatively connected to the third-level BMS control module 12 via an optical fiber. The PCS master control module 21 is communicatively connected to the third-level BMS control module 12 via an Ethernet and / or CAN bus. The PCS master control module 21 is communicatively connected to the PCS power modules 22 via the optical fiber. The PCS power modules 22 are also connected to the second-level BMS control modules 11. Each PCS power module 22 is connected to at least two second-level BMS control modules 11.

[0046] Specifically, the batteries in a high-voltage cascaded energy storage system can be divided into three levels from bottom to top: battery pack level, battery cluster level, and battery stack level. Each level of battery has its own corresponding BMS for management.

[0047] The battery pack is the individual battery cell of the energy storage system. Each battery pack is connected to a primary BMS control module, which is the battery pack management unit (BMU). The primary BMS control module is used to perform fine-grained management of each battery pack. For example, it can collect the voltage and temperature of individual cells in real time and monitor the safety status of the cells. At the same time, it can also perform thermal management control and passive balancing. After aggregating the battery pack data of each battery pack, the primary BMS control module uploads it to the secondary BMS control module 11 via the CAN bus to report the abnormal and fault status of each battery pack in real time.

[0048] A battery cluster is composed of battery modules connected in series, consisting of multiple battery packs. Each battery cluster is connected to a secondary BMS control module 11, which is a battery cluster management unit (BCMU). The secondary BMS control module is used to perform battery cluster-level management of each battery cluster. For example, it collects the total voltage and total current of the battery cluster, receives individual battery data uploaded by the primary BMS control module, completes cluster-level SOC / SOH estimation and equalization strategy judgment, and realizes fault diagnosis and safety protection control of the battery cluster. The secondary BMS control module also communicates with the upper-level tertiary BMS control module 12 and automatically responds to and executes the control strategy of the tertiary BMS control module 12.

[0049] The battery stack is formed by connecting multiple battery clusters in parallel. Each battery stack is connected to a three - level BMS control module 12. The three - level BMS control module 12 is the battery stack / battery compartment management unit (EMU), and it is used to perform battery stack / battery compartment level management on each battery stack. The three - level BMS control module 12 can collect all - quantity data such as voltage, current, temperature, SOC, etc. uploaded by all the lower - level second - level BMS control modules 11; and perform data analysis, fault management, communication coordination, data recording, safety protection, and system self - check diagnosis; to achieve energy scheduling, parameter configuration, and event storage.

[0050] The three - level BMS control module 12 communicates and interacts with the PCS master control module 21 through Ethernet and / or CAN bus. According to the SOC and power demand, it optimizes the load distribution of each battery stack, battery cluster, and battery pack, and realizes the BMS - PCS linkage control. The three - level BMS control module 12 is communicatively connected to the PCS master control module 21 through Ethernet, and can transmit all - quantity data of the battery system, providing data support for PCS power closed - loop regulation, current - limiting strategy, and charge - discharge management. The all - quantity data of the battery system includes cluster voltage, temperature, single - cell SOC, SOH, fault status, balance status, etc.

[0051] Preferably, the three - level BMS control module 12 and the PCS master control module 21 use the Modbus TCP protocol for data interaction, which can clarify the range of interaction data and ensure the real - time synchronization of core parameters. The specific interaction data includes: cluster average SOC, total voltage of the battery cluster, charge - discharge current, fault level, charge - discharge prohibition status, voltage extreme values (highest / lowest single - cell voltage), temperature extreme values (highest / lowest single - cell temperature), etc. The protocol data transmission rate is preferably set to 100 Mbps, and the communication cycle ≤ 100 ms, ensuring the real - time and accuracy of data transmission.

[0052] In this embodiment, the BMS adopts a hierarchical communication method. Among them, the first - level BMS control module and the second - level BMS control module 11 are communicatively connected through the CAN bus, and the communication protocol between them is compatible with CAN2.0B, realizing the unified polling, data collection, and instruction scheduling of all the first - level BMS control modules within the cluster by the second - level BMS control module 11, ensuring high real - time data collection and control synchronization at the battery - pack level. The second - level BMS control module 11 and the three - level BMS control module 12 are connected by optical fiber, which can achieve strong electrical isolation, completely block the interference of the high - voltage circuit, improve the communication insulation withstand voltage level, and eliminate high - voltage electromagnetic interference (EMI), ensuring the stability of the data link under extreme working conditions.

[0053] The PCS adopts a two-level architecture of main control module-power module. The PCS main control module 21 is connected to the PCS power module 22 through the optical fiber. The PCS main control module 21 performs power command issuance, status acquisition, operation monitoring and synchronization control on each PCS main control module 22. At the same time, by utilizing the characteristics of high insulation, strong anti-interference and long distance of optical fiber, the stability of the parallel control of multiple modules in the high-voltage energy storage compartment can be guaranteed.

[0054] In this embodiment, the PCS power module 22 is also connected to the secondary BMS control module 11. Each PCS power module 22 is connected to at least two secondary BMS control modules 11, meaning that at least two secondary BMS control modules 11 are configured in the same PCS controlled loop, enabling a redundancy protection mechanism for the secondary BMS control modules 11. For example, when a secondary BMS control module 11 experiences a fault, power failure, or communication interruption, the PCS power module 22 can immediately detect the anomaly and trigger protection (e.g., activate another secondary BMS control module 11) to prevent system loss of control and improve the availability of the secondary BMS control modules 11.

[0055] The high-voltage cascaded energy storage system provided in this application embodiment includes a battery management system (BMS) and a power storage converter (PCS). The battery management system comprises a first-level BMS control module (not shown in the figure), a second-level BMS control module 11, and a third-level BMS control module 12 connected sequentially from bottom to top. The power storage converter includes a PCS master control module 21 and multiple PCS power modules 22. The first-level BMS control module is communicatively connected to the second-level BMS control module 11 via a CAN bus. The second-level BMS control module 11 is communicatively connected to the third-level BMS control module 12 via an optical fiber. The PCS master control module 21 is communicatively connected to the third-level BMS control module 12 via an Ethernet and / or CAN bus. 21 is connected to the PCS power module 22 via the optical fiber. The PCS power module 22 is also connected to the secondary BMS control module 11. Each PCS power module 22 is connected to at least two secondary BMS control modules 11. Through a hierarchical distributed and strongly electrically isolated communication connection architecture, the communication reliability and stability of the energy storage system can be improved, and communication security and compatibility can be guaranteed. At the same time, through the cooperation of the PCS master control module 21, PCS power module 22, secondary BMS control module 11 and tertiary BMS control module 12, inter-pile collaborative control and inter-cluster collaborative control can be performed, improving control accuracy and efficiency, enhancing the safety of the energy storage system, extending battery life, and improving the overall operating efficiency of the energy storage system.

[0056] Specifically, in this embodiment, the BMS uses CAN+fiber layered communication, and the secondary BMS is configured with dual network redundancy and optical converter modules to enhance communication insulation and anti-interference capabilities. The BMS and PCS, as well as the internal communication of the PCS, adopt targeted communication methods to achieve real-time data interaction and rapid command response, solving the problems of easy interruption and poor anti-interference in the existing communication architecture, and improving the reliability of energy storage system communication.

[0057] The energy storage system boasts strong safety and compatibility: Through measures such as fiber optic communication, dry contact redundancy design, and insulation testing, the operational safety of the energy storage system under high-voltage environments is enhanced; the adoption of the standardized Modbus TCP protocol ensures compatibility with PCS and BMS equipment from different manufacturers, reducing system integration difficulty and improving the universality and scalability of the energy storage system's communication.

[0058] As an optional embodiment, an optical converter 41 and an optical conversion module 42 are provided between the secondary BMS control module 11 and the tertiary BMS control module 12. The tertiary BMS control module 12 is connected to the optical converter 41 via Ethernet and CAN bus respectively. The optical converter 41 is connected to one end of the optical conversion module 42 via optical fiber. The other end of the optical conversion module 42 is connected to the secondary BMS control module 11 via the CAN bus. The secondary BMS control module 11 is also connected to the PCS power module 22 via the CAN bus.

[0059] like Figure 1 As shown, in this embodiment, dual-network redundancy is configured in the secondary BMS control module, and the CAN signal and Ethernet signal are converted into optical signal transmission via optical converter 41, which further improves the communication insulation withstand voltage level, eliminates high voltage electromagnetic interference (EMI), and ensures the stability of the data link under extreme operating conditions.

[0060] The secondary BMS control module 11 is configured with two independent CAN channels. One CAN channel is connected to the optical conversion module 42 and communicates with the tertiary BMS control module via optical fiber. The other channel is directly connected to the local panel of the PCS power module 22 for on-site debugging and local operation.

[0061] As an optional embodiment, the PCS master control module 21 is also connected to the PCS power module 22 via a dry contact, and the secondary BMS control module 11 is connected in series to the controlled circuit of the PCS power module 22 via a dry contact.

[0062] like Figure 1 As shown, the PCS master control module 21 is connected to the PCS power module 22 via a dry contact. The dry contact linkage serves as an auxiliary communication method. Combined with the fiber optic communication between the PCS master control module 21 and the PCS power module 22, it can effectively adapt to the parallel synchronous control of high-voltage cascaded multi-modules.

[0063] The dry contact signals of each PCS power module 22 are connected in series to the PCS valve control circuit to achieve synchronous switching action of all PCS power modules 22DE. If any PCS power module 22 malfunctions, the entire PCS valve control circuit fails, forcing the energy storage system to shut down, thus ensuring consistency and safety under the cascaded topology.

[0064] The secondary BMS control module 11 can connect to the PCS power module 22 not only via the CAN bus, but also via dry contacts. Specifically, the normally closed dry contacts of the secondary BMS control module 11 are connected in series to the PCS valve control circuit. When any secondary BMS control module 11 fails, loses power, or experiences a communication interruption, the series circuit is broken; the PCS power module 22 immediately detects the abnormality and triggers protection to prevent the energy storage system from going out of control and improve the availability of the energy storage system.

[0065] The secondary BMS control module 11 is connected to the PCS power module 22 via dry contact (DO) hard wiring, which can transmit safety-critical signals such as fault shutdown, emergency stop, and status feedback. It is protocol-independent, has a millisecond-level response, and ensures the fastest protection action under fault conditions.

[0066] In this embodiment, the BMS and PCS adopt a hierarchical interface design with hard-wired key signals (between the secondary BMS control module 11 and the PCS power module 22) and Ethernet data (between the PCS main control module 21 and the tertiary BMS control module 12). This design enables the decoupling of safety control and collaborative scheduling, thereby improving the reliability of the high-voltage cascaded energy storage system.

[0067] As an optional embodiment, the three-level BMS control module 12 includes a data aggregation unit 121, which is configured as follows:

[0068] Receive single-cell cluster data from each of the secondary BMS control modules 11, and summarize the single-cell cluster data of multiple secondary BMS control modules 11 corresponding to the same PCS power module 22;

[0069] The PCS master control module 21 includes a power distribution unit 211, which is configured as follows:

[0070] Based on the battery stack data of each of the three-level BMS control modules 12, the power of each battery stack is allocated, and / or, based on the aggregated data of the data aggregation unit 121 and the single battery cluster data, the power of multiple battery clusters corresponding to the same PCS power module 22 is allocated.

[0071] like Figure 1 and Figure 2As shown, the data aggregation unit 121 of the three-level BMS control module 12 can aggregate the data of the two-level BMS control modules 11 corresponding to at least two battery clusters (or two battery clusters) under the same PCS power module 22, thereby aggregating the battery cluster data of at least two battery clusters.

[0072] The summarized data includes, but is not limited to: the average SOC of the two battery clusters, the allowable charging and discharging power, the total charging and discharging current, the maximum fault level (classified according to the severity of the fault, with the highest level taken as the summary result), and the prohibited charging and discharging status (when any battery cluster is in a prohibited charging / discharging status, the summarized status is prohibited charging / discharging).

[0073] The aggregated data can be uploaded to the PCS master control module 21 in real time, providing unified data support for the power regulation and fault diagnosis of the PCS master control module 21, and realizing the coordinated control of the two battery clusters.

[0074] In this embodiment, the PCS master control module 21 combines the real-time state differences between the two battery packs to achieve coordinated power adjustment through "unified scheduling and dynamic allocation". The specific logic is as follows:

[0075] 1) Determination of charging and discharging reference power: The power distribution unit 211 of the PCS master control module 21 receives the average SOC of the stack battery uploaded by the three-level BMS control module 12, and determines the current allowable total charging and discharging reference power (to avoid single cluster overload or SOC imbalance) in combination with the grid dispatch instructions and the overall power demand of the energy storage system. At the same time, with reference to the total charging and discharging current, it is determined whether the total load of the current stack battery is within the safe range. If it exceeds the safe threshold, current limiting adjustment is triggered first.

[0076] 2) Power distribution collaborative control: The three-level BMS control module 12 synchronizes the SOC and individual cell voltage balance status of each battery stack to the power distribution unit 211 in real time (uploaded synchronously with the summarized data). Based on the average SOC value summarized by the three-level BMS control module 12, the power distribution unit 211 performs differentiated power distribution on the battery stack to realize the power collaborative control of the battery stack.

[0077] (1) When there is a deviation in the SOC of the battery stack (e.g., battery 1 SOC 85%, battery stack 2 SOC 75%, and the average SOC of the battery stack after summing is 80%), the power distribution unit 211 will tilt the charging and discharging power towards the stack with lower SOC (stack 2 is allocated higher charging power and battery stack 1 is allocated lower charging power, or battery stack 2 is allocated lower discharging power and battery stack 1 is allocated higher discharging power) to avoid the SOC of a single battery stack being too high or too low, and gradually reduce the SOC difference between the batteries in each stack.

[0078] (2) When the sum of the charging and discharging currents approaches the safety limit of the energy storage system, the power distribution unit 211 reduces the charging and discharging power of the stack proportionally based on the single stack current data uploaded by the three-level BMS control module 12, so as to ensure that the total current does not exceed the limit, and at the same time ensure that the load distribution of each stack is balanced, so as to avoid damage to the battery due to single stack current overload.

[0079] (3) If the overall state of the three-level BMS control module 12 is prohibited from charging or discharging (any cluster triggers prohibited charging / discharging), the power distribution unit 211 immediately stops the corresponding charging and discharging operation and prohibits the stacked battery from performing related actions until the prohibited charging and discharging state of the three-level BMS control module 12 is lifted, so as to ensure system safety.

[0080] In this embodiment, the data aggregation unit 121 of the three-level BMS control module 12 cooperates with the power distribution unit 211 of the PCS master control module 21 to achieve closed-loop power regulation: the data aggregation unit 121 updates the aggregated data and single-cluster subdivision data every 100ms, and the power distribution unit 211 dynamically adjusts the power distribution ratio of the two clusters of batteries according to the real-time aggregated SOC average value and the sum of charging and discharging current, forming a closed loop of "EMU data aggregation → PCS command issuance → stack (two clusters) power execution → EMU data feedback", realizing the coordination and real-time performance of power regulation.

[0081] As an optional embodiment, the three-level BMS control module 12 further includes a first fault handling unit 122, which is configured as follows:

[0082] Determine the fault level of multiple battery clusters corresponding to the same PCS power module 22, and determine the comprehensive fault level based on the fault level of each battery cluster;

[0083] The PCS master control module 21 further includes a second fault handling unit 212, which is configured as follows:

[0084] Based on the comprehensive fault level and fault information of the fault clusters, fault handling is performed on multiple battery clusters.

[0085] like Figure 2 As shown, the data aggregation unit 121 can aggregate the fault level and charge / discharge prohibited status of each battery cluster and / or battery stack, and send it to the PCS central control module 21. Based on the aggregated data, the PCS central control module 21 can determine the fault of at least two battery clusters in the energy storage system and execute corresponding protection actions to achieve accurate fault judgment and graded handling.

[0086] In this embodiment, the first fault handling unit 122 of the three-level BMS control module 12 can classify the faults of a single battery cluster into multiple fault levels according to the severity of the fault. For example, in this embodiment, it can be divided into three levels: Level 3: minor alarm, not affecting operation; Level 2: moderate fault, power limitation; Level 1: severe fault, requiring shutdown. The first fault handling unit 122 can use the maximum value of the fault levels of multiple battery clusters as the current fault level of the battery stack and upload it to the second fault handling unit 212 of the PCS master control module 21 in real time. The second fault handling unit 212 executes corresponding protection actions according to the fault levels of each battery stack in the three-level BMS control module 12, and at the same time, combined with the single-cluster fault information synchronously uploaded by the first fault handling unit 122, locates the faulty cluster, and realizes the graded collaborative processing of faults of multiple battery clusters.

[0087] If the fault level determined by the first fault handling unit 122 is level 3 (minor alarm): the PCS main control module 21 continues to operate normally, and at the same time, it sends alarm prompts to each cluster of batteries through the first fault handling unit 122, and monitors the status changes of the faulty clusters in a synchronous manner. If the fault escalates, the handling strategy is adjusted immediately.

[0088] If the fault level determined by the first fault handling unit 122 is level 2 (medium fault): the PCS main control module 21 limits the charging and discharging power of the fault cluster according to the location result of the fault cluster (for example, reducing the load of the fault cluster to avoid the fault from expanding), controls the normal operation of the non-fault cluster, and adjusts the total power output based on the sum of the charging and discharging currents summarized by the three-level BMS control module 12 to ensure the overall stable operation of the energy storage system.

[0089] If the overall fault level determined by the first fault handling unit 122 is Level 1 (serious fault): the PCS main control module 21 immediately triggers the shutdown protection, prohibits the charging and discharging of the two battery clusters, and locks the fault status, waiting for maintenance personnel to investigate; at this time, the EMU continues to summarize the fault data to provide a basis for fault investigation.

[0090] Furthermore, when the charging / discharging restriction status summarized by the Level 3 BMS control module 12 is triggered (any cluster triggers charging / discharging restriction due to a fault), the PCS central control module 21 can determine that there is a "system-level safety hazard" in the energy storage system, immediately execute the corresponding charging / discharging restriction operation, and at the same time synchronize the single-cluster fault information uploaded by the EMU to clarify the triggering reason for the charging / discharging restriction, provide accurate guidance for fault handling, and prevent the fault from spreading to another cluster.

[0091] In this embodiment, a fault control strategy of "layered detection and graded response" is adopted, clearly defining the control division of labor between BMS and PCS to ensure timely fault handling. Specifically, the PCS performs DC-side contactor control, AC-side power control, and grid connection control; the BMS is used for fault diagnosis on the DC battery side (including battery overcharge, over-discharge, over-temperature, insulation abnormalities, current abnormalities, etc.) and fault shutdown output control.

[0092] The secondary BMS control module 11 can receive battery module data collected by the primary BMS control module and complete battery cluster total voltage acquisition, insulation detection, fault diagnosis, etc. Among them, current acquisition is connected to the CAN0 interface of the BCMU through a CAN Hall sensor to achieve accurate acquisition and transmission of current signals.

[0093] When the BMS detects a DC-side fault, it outputs a fault shutdown command to the PCS via the dry contact (DO). Upon receiving the command, the PCS immediately stops the AC-side power output. At the same time, the BMS cuts off the power supply to the battery cluster to prevent the fault from escalating and achieves timely fault response and handling. After the fault is cleared, the energy storage system automatically or manually restarts and resumes normal operation.

[0094] In this embodiment, the coordinated control of the two battery clusters is based on the data aggregation of the stack-level three-stage BMS control module 12, and relies on the Ethernet communication between the three-stage BMS control module 12 and the PCS master control module 21 to achieve full-process coordination of "data aggregation → command issuance → status feedback → dynamic adjustment". The specific coordinated control process is as follows:

[0095] 1) Data collaborative acquisition and aggregation: The three-level BMS control module 12 collects data such as SOC, charging and discharging current, fault level, and charging and discharging prohibition status of the two battery clusters in real time, and completes the aggregation processing (averaging SOC, summing current, taking the maximum value of fault level, and using "OR" logic for charging and discharging prohibition status) to ensure the uniformity and integrity of the data of the two clusters and provide a data foundation for collaborative control.

[0096] 2) Coordinated command issuance and execution: Based on the data collected by the three-level BMS control module 12 and combined with the overall system requirements, the PCS master control module 12 issues unified power adjustment commands and fault protection commands, which are transmitted to the two-level BMS control modules 11 (BCMU) of the two battery clusters through the three-level BMS control module 12. After receiving the control commands, the two-level BMS control modules 11 synchronously control the first-level BMS control modules (BMU) in their respective clusters to perform operations such as charging and discharging power adjustment, fault diagnosis, and charging and discharging prohibition, to ensure that the two battery clusters act in a coordinated and consistent manner.

[0097] 3) Status Coordination Monitoring and Feedback: The three-level BMS control module 12 monitors the execution status of the two battery clusters in real time, compares the deviation between the PCS master control command and the actual operating status, incorporates the deviation data into the summary information, and feeds it back to the PCS master control in real time; the PCS master control dynamically adjusts the command according to the deviation data to ensure that the operating status of the two battery clusters is always consistent with the system requirements, avoids the deviation of a single cluster from the control target, and realizes the coordinated operation of the two clusters.

[0098] 4) Collaborative handling of anomalies: When any cluster experiences an anomaly such as a fault, SOC imbalance, or current overload, the three-level BMS control module 12 quickly captures the anomaly of the battery cluster by summarizing the data (such as an increase in fault level, excessive SOC deviation, or excessive total current), and reports it to the PCS master control module 21 in real time; the PCS master control module 21 immediately triggers the collaborative handling strategy, adjusts the power distribution of the two battery clusters, executes fault protection, avoids the spread of anomalies, and ensures the safe, stable, and collaborative operation of the two battery clusters.

[0099] As described above, the three-level BMS control module 12 integrates information from multiple battery clusters (e.g., two clusters) through data aggregation. The PCS master control module 21 then performs power regulation and fault diagnosis based on the aggregated data. Through the linkage between the three-level BMS control module 12 and each level of BMS, control commands are synchronized to multiple battery clusters, ultimately achieving coordinated control of the multiple battery clusters and ensuring the efficient and safe operation of the energy storage system. Similarly, the PCS master control module 21 can integrate information from multiple battery stacks through data aggregation. Based on the aggregated data, the PCS master control module 21 performs power regulation and fault diagnosis of the battery stack. Through the linkage between the three-level BMS control module 12 and each level of BMS, control commands are synchronized to multiple battery stacks, ultimately achieving coordinated control of the multiple battery stacks and ensuring the efficient and safe operation of the energy storage system.

[0100] As an optional embodiment, at least one of the multiple secondary BMS control modules 11 connected to the same PCS power module 22 is connected to the main battery cluster, and at least one of the multiple secondary BMS control modules 11 is connected to the slave battery cluster; the main battery cluster includes a main cluster precharge contactor and a main cluster main DC contactor, and the slave battery cluster includes a slave cluster main DC contactor and a slave cluster circulating current contactor; the main cluster precharge contactor, the main cluster main DC contactor, the slave cluster main DC contactor, and the slave cluster circulating current contactor are respectively connected to the PCS master control module;

[0101] The PCS master control module 21 includes a precharge control unit 213, which is configured to control the main cluster precharge contactor to close to precharge the main battery cluster, and control the main cluster main DC contactor according to the precharge result to control the operation of the main battery cluster; the precharge control unit 213 is also configured to control the slave cluster main DC contactor and the slave cluster circulating current contactor based on the inter-cluster voltage difference between the main battery cluster and the slave battery cluster after the main battery cluster is powered on, so as to control the operation of the slave battery cluster.

[0102] like Figure 1 and Figure 4 As shown, for a typical topology in a high-voltage cascaded energy storage system where a single PCS power module 22 carries two battery clusters in parallel, in this embodiment, the PCS master control module 21 can perform pre-charge control on the master and slave battery clusters through a graded differential pressure adaptive pre-charge control strategy.

[0103] Specifically, the main battery cluster (hereinafter referred to as the main cluster) enters the pre-charging stage first. The prerequisites for starting the pre-charging include: the energy storage system completes self-test and has no level one fault, receives a legal power-on command remotely or locally issued by the energy management system 3 (EMS), and the DC side insulation test is qualified (e.g., insulation resistance ≥1000Ω / V).

[0104] The third-level BMS control module 12 sends a pre-charge command to the PCS master control module 21. The pre-charge control unit 213 controls the main cluster pre-charge contactor to close, and performs current-limited charging on the PCS DC bus through the pre-charge current-limiting resistor. During the pre-charge process, the second-level BMS control module 11 and the PCS master control module 21 respectively collect the main cluster battery total voltage and the PCS DC bus voltage in real time, with a sampling period of ≤10ms and a detection accuracy of ±10V. The PCS master control module 21 determines whether the main cluster has completed pre-charge based on the real-time collected data. If the main cluster has completed pre-charge, the pre-charge control unit 213 disconnects the main cluster pre-charge contactor and closes the main cluster main DC contactor to complete the main cluster power-on.

[0105] Preferably, if the difference between the total voltage of the main cluster battery and the DC bus voltage of the PCS is ≤10V, and the pre-charging current is ≤50A and the pre-charging duration is ≤3s, the main cluster is considered to have completed pre-charging.

[0106] If the pre-charge time exceeds 5 seconds and the judgment criteria for the main cluster pre-charge completion are not met, the secondary BMS control module 11 and / or the pre-charge control unit 213 can trigger a pre-charge timeout fault, cut off all pre-charge circuits, prohibit subsequent power-on operations, and provide pre-charge timeout protection for the main cluster.

[0107] After the master cluster is powered on, the three-level BMS control module 12 synchronously collects the total battery voltage of the master cluster and slave battery clusters (slave clusters) and calculates the inter-cluster voltage difference. And determine whether to pre-charge the slave cluster based on the pressure difference.

[0108] As an optional embodiment, the three-level BMS control module 12 further includes a differential pressure judgment unit 123, configured as follows:

[0109] If the inter-cluster pressure difference is less than or equal to the first pressure difference threshold, it is determined that the inter-cluster pressure difference is within the pressure difference safe range.

[0110] If the inter-cluster pressure difference is greater than the first pressure difference threshold and less than the second pressure difference threshold, it is determined that the inter-cluster pressure difference is in the pressure difference equilibrium range.

[0111] If the inter-cluster pressure difference is greater than or equal to the second pressure difference threshold, the inter-cluster pressure difference is determined to be in the pressure difference danger range.

[0112] The precharge control unit 213 is configured to: control the main DC contactor of the slave cluster to close when the inter-cluster pressure difference is within the safe range of the pressure difference, so as to precharge the slave battery cluster; and control the circulating contactor of the slave cluster to close when the inter-cluster pressure difference is within the range of the pressure difference that can be balanced, so as to adjust the inter-cluster pressure difference.

[0113] The differential pressure judgment unit 123 divides the differential pressure magnitude into three levels. If the inter-cluster differential pressure is less than or equal to the first differential pressure threshold, for example, The inter-cluster pressure difference was determined to be within the safe pressure difference range, where, The inter-cluster pressure difference The first differential pressure threshold can be configured as needed via a host computer to adapt to systems with different voltage levels. If the inter-cluster differential pressure is greater than the first differential pressure threshold but less than the second differential pressure threshold, for example, The inter-cluster pressure difference is determined to be within a pressure difference equilibration range. The second pressure difference threshold can be configured based on the electrical component selection threshold. If the inter-cluster pressure difference is greater than or equal to the second pressure difference threshold, for example, The inter-cluster pressure difference was determined to be within the dangerous pressure difference range.

[0114] like Figure 4 As shown, the pre-charge control unit 213 performs three-level differentiated control on the slave clusters based on the range of inter-cluster pressure difference mentioned above:

[0115] (1) When the inter-cluster pressure difference is within the safe range of the pressure difference, the third-level BMS control module 12 sends a slave cluster power-on command to the PCS master control module 21, and the pre-charge control unit 213 directly closes the slave cluster master DC contactor to complete the parallel connection of the two clusters of batteries. After the slave cluster master DC contactor is closed, the second-level BMS control module 11 and the PCS master control module 21 continuously monitor the total DC current. If the total DC current is 300ms, the impact current is ≤80A, and there is no abnormal fluctuation, the pre-charge of the slave cluster is confirmed to be completed.

[0116] (2) When the inter-cluster pressure difference is within the pressure difference equalization range, the three-level BMS control module 12 sends a circulating current equalization command to the PCS main control module 21. The pre-charge control unit 213 closes the circulating current contactor of the slave cluster, realizing energy transfer (energy flows from the high-voltage cluster to the low-voltage cluster) through the bidirectional circulating current loop between the PCS DC side bus and the slave cluster, and adjusting the inter-cluster pressure difference in real time. During the equalization process, the pressure difference data can be updated every 10ms. When the precharge control unit 213 disconnects the cluster circulating contactor, it executes the aforementioned cluster power-on process within the differential pressure safety range again.

[0117] Preferably, the PCS master control module 21 can perform equalization timeout protection. If the circulating current equalization continues for 60 seconds and still fails to reduce the voltage difference to below 10V, the precharge control unit 213 of the PCS master control module 21 will immediately terminate the equalization and trigger a precharge equalization fault.

[0118] (3) When the inter-cluster pressure difference is in the dangerous range of pressure difference, the pre-charge control unit 213 immediately triggers the first-level pre-charge fault alarm and prohibits any power-on operation from the cluster. At the same time, the third-level BMS control module 12 synchronously uploads the fault code, pressure difference value and fault time to the PCS main control module 21 and the EMS system. Only after the cause of the pressure difference abnormality is determined by manual investigation and the fault is reset can the pre-charge process be restarted.

[0119] After pre-charging, once both battery clusters are fully connected in parallel, the PCS main control module 21 continuously monitors the total DC voltage, total current, and current of each cluster for 1 second. Once the parameters are confirmed to be stable and without abnormalities, the pre-charging process ends, and the system enters standby mode, awaiting power dispatch commands. During the entire pre-charging process, if overcurrent, overvoltage (DC voltage > 1.1 times the rated voltage), insulation abnormality, or communication interruption is detected, an emergency shutdown is immediately executed: the PCS main control module 21 disconnects all AC / DC contactors, the BMS disconnects the battery cluster output, and simultaneously triggers the corresponding fault alarm.

[0120] As can be seen from the above, the embodiments of this application, through the pre-charge control method that combines master-slave cluster time-sharing pre-charge, inter-cluster voltage difference classification determination and circulating current active balancing, can fundamentally avoid DC inrush current caused by excessive inter-cluster voltage difference, while taking into account both pre-charge efficiency and system safety.

[0121] As an optional embodiment, the PCS master control module 21 further includes a balance control unit 214, which is configured as follows:

[0122] Based on the preset total output power of the energy storage system and the SOC deviation ratio of each battery stack, the inter-stack equalization adjustment is performed on multiple battery stacks.

[0123] Based on the active power of the PCS and the SOC deviation ratio of each phase battery cluster in the three-phase battery cluster, phase-to-phase equalization adjustment is performed on multiple battery stacks, wherein each phase battery cluster includes at least one of the PCS power modules.

[0124] The PCS master control module 21 also includes an inter-stack equalization safety control unit 215, configured to: monitor the operating data of each battery stack during the inter-stack equalization adjustment process, and perform equalization safety control based on the operating data of the battery stack.

[0125] The secondary BMS control module 11 is configured to monitor the operating data of each battery cluster during the process of inter-stack equalization and inter-phase equalization adjustment, and to perform equalization safety control based on the operating data of the battery cluster.

[0126] In this embodiment, the PCS master control module 21, the secondary BMS control module 11, and the tertiary BMS control module 13 work together to perform dual SOC balancing between stacks and between phases, which can comprehensively improve the consistency of the battery system and extend the battery life.

[0127] After the pre-charging process is completed, in order to comprehensively improve the consistency of the battery pack of the high-voltage cascaded energy storage system, reduce the difference in individual cell degradation, and extend the overall battery life, this embodiment adopts a dual SOC equalization control strategy between stacks and between phases. Through precise power allocation and a constant total power scheduling mechanism, it achieves comprehensive coverage of battery system SOC equalization, taking into account both system power output stability and battery safety.

[0128] For high-voltage cascaded energy storage systems with multiple battery stacks, in order to improve the overall battery consistency of the system and ensure the coordinated charging and discharging of each battery stack, this embodiment relies on the PCS master control to reasonably allocate the charging and discharging power of each stack according to the real-time SOC status of each battery stack while keeping the total output power of the system constant. This achieves SOC balance between stacks, avoids overcharging and over-discharging of some battery stacks, and ensures the stability of the overall power output of the system, thus ensuring the accurate execution of subsequent phase-to-phase SOC balancing.

[0129] like Figure 3 As shown, the equalization control unit 214 performs inter-pile SOC detection and determination: the three-level BMS control module 13 collects the SOC value of each battery stack in real time (the arithmetic mean of the SOC of all clusters under each stack is taken as the SOC benchmark value of that stack), with a sampling period of ≤10ms and a detection accuracy of ±0.5%; at the same time, it calculates the deviation between the SOC of each battery stack and the system average SOC. The preset inter-stack SOC balancing start-up threshold (default 5%, configurable via host computer) is set when any battery stack... When the threshold is exceeded, inter-heap SOC leveling control is initiated.

[0130] The equalization control unit 214 performs inter-stall equalization based on a constant total power. The equalization control unit 214 receives SOC data for each stack and the system's total output power command (which can be uniformly scheduled by the EMS and kept constant) transmitted from the three-level BMS control module 13. It uses a "deviation ratio allocation method" to allocate the charging and discharging power of each battery stack. The core principle of power allocation is: battery stacks with an SOC higher than the system average SOC bear more discharge power (or less charging power); battery stacks with an SOC lower than the system average SOC bear less discharge power (or more charging power), ensuring that the sum of the power adjustments for each stack is 0, without changing the system's total output power.

[0131] In the specific allocation, firstly, the SOC deviation ratio of each battery stack is calculated. (The sum of deviations of all battery stacks exceeding the threshold) and then allocate power adjustment amount according to the deviation ratio; the power adjustment step size is adapted to the total system power. For example, the power adjustment step size is set to 1%~5% of the total output power, and the adjustment response time is set to ≤50ms to avoid the impact of power sudden changes on the system. For example, if the total system discharge power is constant at 10MW, and the SOC of one battery stack is 5% higher than the system average, while that of another battery stack is 5% lower than the system average, then the discharge power of the high SOC stack will be increased by 0.5MW, and the discharge power of the low SOC stack will be decreased by 0.5MW, keeping the total discharge power unchanged at 10MW. By allocating power, the discharge of the high SOC stack is accelerated, and the discharge of the low SOC stack is slowed down, gradually reducing the SOC deviation between stacks.

[0132] During inter-stack equalization control, the equalization control unit 214 can achieve closed-loop feedback of equalization through an inter-stack SOC equalization closed-loop feedback mechanism. The three-level BMS control module 13 can feed back real-time SOC data of each battery stack to the PCS master control module 21 every 20ms. The PCS master control module 21 dynamically adjusts the power allocation scheme of each stack based on the feedback data, continuously adjusting until all battery stacks are equalized. ≤2 (inter-reactor equalization termination threshold), stop inter-reactor power regulation, and complete inter-reactor SOC equalization.

[0133] During inter-pile equalization, the inter-pile equalization safety control unit 215 of the PCS master control module 21 monitors the charging and discharging current, total voltage, and individual cell status of each battery pile in real time to ensure that the charging and discharging current of each pile does not exceed the preset current threshold (e.g., 1.1 times the rated current) and the individual cell voltage is maintained within the preset voltage range (e.g., 2.5~3.6V). If the inter-pile equalization safety control unit 215 detects overcurrent, overvoltage, overtemperature, or insulation abnormality in a battery pile, it immediately suspends the power regulation of that pile, prioritizes fault protection, and restarts inter-pile equalization after the fault is cleared, ensuring the equalization process and the overall system operation safety.

[0134] Having achieved inter-pile SOC equalization and ensured that the SOC of each battery stack tends to be consistent, to further refine the equalization control and solve the SOC deviation problem between phases, the equalization control unit 214 can activate the inter-phase equalization mechanism. This mechanism employs a PCS active power dynamic allocation strategy to achieve inter-phase SOC equalization, avoiding system efficiency degradation and accelerated battery degradation caused by inter-phase power imbalance. Specifically, the three-level BMS control module 13 collects the SOC data of the three-phase battery clusters in real time. For each phase, the arithmetic mean of the SOC of all battery clusters under the corresponding PCS is taken as the average SOC value for that phase, and the inter-phase SOC difference is calculated. ;when When the power exceeds a preset threshold (e.g., 7%, which can be adjusted as needed), the three-level BMS control module 13 sends a power allocation command to the PCS master control module 21. The command determines the charging and discharging power adjustment target for each phase, following the principle of "more discharge and less charging for phases with high SOC, and less discharge and more charging for phases with low SOC." The charging and discharging power is dynamically allocated to each phase according to the SOC deviation ratio. The power adjustment step size is preferably 5~10kW (e.g., 10kW), and the adjustment response time is preferably ≤50ms to ensure equalization efficiency. Simultaneously, a closed-loop feedback mechanism for equalization is established. The three-level BMS control module 13 feeds back real-time SOC data for each phase to the PCS master control module 21 every 20ms. The PCS master control module corrects the power allocation scheme based on the feedback data until ΔSOC_2≤3 (equalization termination threshold), at which point power adjustment stops, achieving phase-to-phase SOC equalization.

[0135] During inter-pile and inter-phase SOC equalization, the secondary BMS control module 11 monitors the voltage (e.g., monitoring range 2.5~3.6V, detection accuracy 5mV), battery temperature (e.g., monitoring range -0~55℃, detection accuracy ±0.1℃), and equalization loop current of each battery cluster (including individual cells within the cluster) in real time. If an individual cell voltage exceeds the normal range, the battery temperature rises abnormally (>55℃), or the equalization current fluctuates abnormally (exceeding 20A), all equalization operations are immediately stopped, an equalization fault alarm is triggered, and the fault type, fault location, and real-time parameters are synchronously uploaded to the tertiary BMS control module 13, the PCS master control module 21, and the EMS system. Inter-pile and inter-phase equalization can only be restarted after the fault is investigated and resolved and the parameters return to normal, ensuring the safety and reliability of the equalization process and preventing the fault from affecting the overall system operation.

[0136] As an optional embodiment, the PCS master control module 21 further includes an auxiliary control unit 216 configured to adjust the environmental parameters of the energy storage system, wherein the environmental parameters include at least one of temperature, humidity and light intensity.

[0137] like Figure 3As shown, since high-voltage cascaded energy storage systems are sensitive to environmental temperature and humidity, this embodiment monitors the environmental parameters inside the energy storage compartment in real time and adjusts the environmental parameters through the auxiliary control unit 216 of the PCS main control module 21 to ensure that the energy storage system is in the optimal operating environment, prevents condensation, and ensures the safe and reliable operation of the energy storage system.

[0138] For example, sensors installed inside the energy storage compartment can monitor the battery temperature, ambient temperature, and humidity in real time. Based on these parameters, the temperature and humidity of the energy storage compartment can be adjusted to ensure it operates within the optimal environmental parameter range, which can be: temperature 15-25℃, humidity 40%-60%. When the ambient temperature inside the energy storage compartment exceeds the optimal temperature range, the auxiliary control unit 216 automatically activates the liquid cooling system or air conditioning system to precisely regulate the temperature and prevent the battery from being affected by excessively high or low temperatures, thus protecting its performance and lifespan. When the humidity inside the energy storage compartment exceeds the optimal humidity range or a risk of condensation is detected, the auxiliary control unit 216 automatically activates the dehumidification system to reduce the humidity inside the compartment, prevent condensation, prevent degradation of the insulation performance of high-voltage equipment, and avoid short-circuit faults.

[0139] As can be seen from the above, in this embodiment, the PCS and BMS work together to achieve reasonable and coordinated control of the battery pack, battery cluster, and battery stack of the energy storage system. The control strategy is reasonable and reliable, enabling precise and efficient control of the energy storage system. Specifically, by performing graded pre-charging and inter-cluster voltage difference equalization control on the master and slave cluster batteries, damage to the equipment is avoided due to inrush current; the dual equalization control strategy between stacks and phases comprehensively improves battery consistency and extends battery life; the fault control strategy has a clear division of labor, enabling rapid fault detection and response, and reducing the risk of fault expansion; the auxiliary control strategy specifically optimizes environmental control, eliminating the effects of condensation and abnormal temperature and humidity, and ensuring long-term stable operation of the system.

[0140] According to an embodiment of this application, a control method for a high-voltage cascaded energy storage system is also provided. Figure 5 This is a flowchart of a control method for a high-voltage cascaded energy storage system provided according to an embodiment of this application, such as... Figure 5 As shown, this method is applied to the aforementioned high-voltage cascaded energy storage system, including:

[0141] S101, in response to the control strategy of the secondary BMS control module 11, the operation of at least one battery pack is controlled by the primary BMS control module;

[0142] S102, in response to the control strategy of the third-level BMS control module 12, the operation of at least one battery cluster is controlled by the second-level BMS control module 12;

[0143] S103, in response to the control strategy of the PCS master control module 21, the operation of at least one battery stack is controlled by the three-level BMS control module 12, and the multiple three-level BMS control modules 12 are coordinated and controlled by the PCS master control module 21.

[0144] S104, the PCS master control module 21 performs coordinated control on the multiple secondary BMS control modules 11 connected to the same PCS power module 22.

[0145] It should be noted that there is no specific execution order for steps S101 to S104 above. These steps can be executed simultaneously, or only one or more of them can be executed.

[0146] The control method for the high-voltage cascaded energy storage system provided in this application corresponds to the high-voltage cascaded energy storage system in the above embodiments. Any option in the embodiments of the high-voltage cascaded energy storage system is also applicable to the embodiments of the control method for the high-voltage cascaded energy storage system, and will not be repeated here.

[0147] The high-voltage cascaded energy storage system and its control method provided in this application will be further described in detail below with reference to specific embodiments, so that those skilled in the art can understand them.

[0148] Example 1

[0149] This embodiment provides a communication architecture and control method for a high-voltage cascaded energy storage direct-connection scheme, applied to a 10kV high-voltage cascaded energy storage direct-connection system. The system has a rated power of 10MW and a rated capacity of 20MWh, comprising 30 PCS groups and 60 battery clusters. Each PCS group corresponds to 2 battery clusters, and each battery cluster consists of 4 battery modules connected in series (single module 104s, rated capacity 314Ah). Each battery cluster is equipped with one secondary BCMU (secondary BMS control module 11), and each BCMU corresponds to 4 BMUs (primary BMS control modules). The EMU (tertiary BMS control module 12) corresponds to 60 secondary BCMUs. The stack-level EMU is the DC-side system-level master controller. The specific implementation is as follows:

[0150] I. Communication Architecture Setup

[0151] 1. Internal BMS Communication: The Level 1 BMS and Level 2 BCMU communicate via CAN at a rate of 250kbps, using shielded twisted-pair cable for the communication bus; the Level 2 BCMU and Level 3 BMU communicate via single-mode fiber optic cable with a transmission distance of ≤100m. The Level 2 BCMU is equipped with a dual-network redundant optical converter module to convert CAN signals (250kbps) and Ethernet signals (100Mbps) into optical signals for transmission. One CAN interface is connected to the optical converter module, and the other is connected to the PCS panel, enabling on-site debugging.

[0152] 2. BMS and PCS Communication: Each secondary BCMU connects to its corresponding PCS via a dry contact (DO output, rated voltage DC24V, rated current 1A, response time ≤10ms) to transmit fault shutdown commands; the tertiary EMU connects to the PCS main control module 21 via Ethernet (100Mbps, TCP / IP protocol, transmission distance ≤100m) to upload data such as individual battery voltage, temperature, total voltage, current, and SOX, with a data upload cycle of 100ms; the normally closed dry contacts of two BCMUs under the same PCS are connected in series to the PCS power module 22, with a dry contact operating voltage of DC22~26V and an operating current of 0.5~1A, forming redundant protection to ensure that when any BCMU fails, the PCS can detect the signal abnormality and trigger protection within ≤20ms.

[0153] 3. PCS Internal Communication: The PCS master control module 21 and each PCS power module 22 use single-mode fiber optic communication with a communication cycle of 50ms and an optical transmission rate of 100Mbps. The PCS dry contacts are connected to the PCS valve control in series (to realize valve control linkage control, ensure that the synchronization error of the PCS power module 22 switching action is ≤1ms, and improve the stability and reliability of PCS operation).

[0154] II. Implementation of Control Methods

[0155] 1. Protocol and Data Aggregation: The stack-level EMU and the PCS master control module 21 use the Modbus TCP protocol with a communication cycle of 80ms, 8 data bits, 1 stop bit, and no parity bit. The exchanged data includes cluster average SOC, total voltage, charging and discharging current, fault level, etc. The stack-level EMU aggregates the SOC, current, and other data of two battery clusters under the same PCS power module 22. The aggregation delay is ≤100ms. The aggregated data is uploaded to the PCS master control module in real time with an upload success rate of ≥99.99%.

[0156] 2. Pre-charge control: The main cluster starts pre-charging first. The pre-charging completion conditions are: the main cluster battery voltage reaches 90% of the rated voltage, the pre-charging current is ≤50A, and the pre-charging time is ≤3s. After the pre-charging is completed, the inter-cluster voltage difference Vdiff between the main cluster and the slave cluster is detected by the voltage sensor: if the inter-cluster voltage is 10V<Vdiff<20V, the circulating current loop is started for equalization until Vdiff=10V, and the slave cluster is powered on to complete the pre-charging; if Vdiff≥20V, the pre-charging fault alarm is triggered, the slave cluster is prohibited from being powered on, and a fault signal is output to the PCS main control module 21. The pre-charging is restarted after the voltage difference is investigated and processed.

[0157] 3. Equalization Control: The inter-stack SOC difference threshold is set to 4%, and the inter-phase SOC difference threshold is set to 7%. When the inter-stack SOC difference is detected to be 5%, the inter-stack equalization mechanism is activated, using an active equalization method (equalization current 10A, equalization efficiency ≥95%). The stack SOC is brought to a uniformity through the different output power of the PCS, with an equalization time ≤60min. When the inter-phase SOC difference is 8%, the charging and discharging power of each phase is adjusted through the PCS power module 22, with a power adjustment step size of 10kW and an adjustment response time ≤50ms, to achieve inter-phase SOC equalization. During the equalization process, parameters such as battery voltage (when the single cell voltage is below 2.5V or above 3.6V) and temperature (when the single cell temperature is above 55℃ or below 0℃) are monitored in real time. If any abnormality occurs, the equalization operation is stopped immediately, and a fault alarm is triggered to ensure the safety of the equalization process.

[0158] 4. Fault Control: When the BMS detects faults such as battery overheating (temperature > 55℃), overcharging (single cell voltage > 3.60V), over-discharging (single cell voltage < 2.5V), insulation abnormality (insulation resistance < 1000Ω / V), or current abnormality (charge / discharge current > 220A or < -220A), it outputs a fault shutdown command to the PCS via the dry contact (DO). Upon receiving the command, the PCS power module 22 immediately stops the AC side power output (shutdown response time ≤ 10ms), and at the same time, the BMS cuts off the power supply to the battery cluster (using a DC contactor). After the fault is cleared, the system is manually restarted. Before restarting, insulation testing and voltage verification must be performed to ensure that the system is free of abnormalities.

[0159] 5. Auxiliary Control Strategy: The optimal temperature and humidity range inside the energy storage compartment is set at 15-25℃ and 40%-60%, respectively. Temperature and humidity sensors (measurement accuracy: temperature ±0.5℃, humidity ±2%RH; measurement range: temperature -40~80℃, humidity 0~100%RH) are used for real-time monitoring. When the battery temperature rises to 28℃ or drops to 15℃, the liquid cooling system is activated to cool or heat the battery, ensuring the battery operating temperature is between 18-25℃. When the ambient temperature drops to 12℃ or rises above 28℃, the air conditioning system is activated. When the humidity rises to 70% or condensation is detected, the dehumidification system (model: CS-20kW, dehumidification capacity 20kg / h) is activated to reduce the humidity inside the compartment, prevent condensation, and ensure the insulation performance of the high-voltage equipment (insulation resistance ≥1000Ω / V).

[0160] In this embodiment, the energy storage system exhibits stable communication during operation, with a data transmission success rate of ≥99.99% and no data loss or interruption. The pre-charging process is smooth, with an inrush current ≤80A and a pre-charging success rate of 100%. The SOC consistency between battery clusters and phases is improved to over 98%, and the maximum voltage difference between individual cells is ≤0.05V. The environmental temperature and humidity are precisely controlled, with internal temperature fluctuations ≤±1℃ and humidity fluctuations ≤±3%RH, and no condensation. The system operating efficiency reaches over 92%, and the fault response time is ≤20ms. Safety and reliability are significantly improved, meeting the actual operational requirements of a 10kV high-voltage cascaded energy storage direct-connection system.

[0161] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0162] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0163] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0164] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0165] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0166] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a non-volatile storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0167] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A high-voltage cascaded energy storage system, characterized in that, The device includes a battery management system (BMS) and an energy storage converter. The BMS includes a first-level BMS control module, a second-level BMS control module, and a third-level BMS control module connected sequentially from bottom to top. The energy storage converter includes a PCS master control module and multiple PCS power modules. The first-level BMS control module communicates with the second-level BMS control module via a CAN bus. The second-level BMS control module communicates with the third-level BMS control module via an optical fiber. The PCS master control module communicates with the third-level BMS control module via an Ethernet and / or CAN bus. The PCS master control module communicates with the PCS power modules via the optical fiber. The PCS power modules are also connected to the second-level BMS control modules. Each PCS power module is connected to at least two second-level BMS control modules. At least one of the multiple secondary BMS control modules connected to the same PCS power module is connected to the main battery cluster, and at least one of the multiple secondary BMS control modules is connected to the slave battery cluster; the main battery cluster includes a main cluster precharge contactor and a main cluster main DC contactor, and the slave battery cluster includes a slave cluster main DC contactor and a slave cluster circulating current contactor; the main cluster precharge contactor, the main cluster main DC contactor, the slave cluster main DC contactor, and the slave cluster circulating current contactor are respectively connected to the PCS master control module; The PCS master control module includes a pre-charge control unit, which is configured to control the main cluster pre-charge contactor to close to pre-charge the main battery cluster, and control the main cluster main DC contactor according to the pre-charge result to control the operation of the main battery cluster; the pre-charge control unit is also configured to control the slave cluster main DC contactor and the slave cluster circulating current contactor based on the inter-cluster voltage difference between the main battery cluster and the slave battery cluster after the main battery cluster is powered on, so as to control the operation of the slave battery cluster.

2. The high-voltage cascaded energy storage system according to claim 1, characterized in that, An optical converter and an optical conversion module are provided between the secondary BMS control module and the tertiary BMS control module. The tertiary BMS control module is connected to the optical converter via Ethernet and CAN bus respectively. The optical converter is connected to one end of the optical conversion module via optical fiber. The other end of the optical conversion module is connected to the secondary BMS control module via the CAN bus. The secondary BMS control module is also connected to the PCS power module via the CAN bus.

3. The high-voltage cascaded energy storage system according to claim 1, characterized in that, The PCS master control module is also connected to the PCS power module via a dry contact, and the secondary BMS control module is connected in series to the controlled circuit of the PCS power module via a dry contact.

4. The high-voltage cascaded energy storage system according to claim 1, characterized in that, The three-level BMS control module includes a data aggregation unit, wherein the data aggregation unit is configured as follows: Receive single-cell cluster data from each of the secondary BMS control modules, and aggregate single-cell cluster data from multiple secondary BMS control modules corresponding to the same PCS power module; The PCS master control module includes a power distribution unit, wherein the power distribution unit is configured as follows: Based on the battery stack data of each of the three-level BMS control modules, the power of each battery stack is allocated, and / or, based on the aggregated data of the data aggregation unit and the single battery cluster data, the power of multiple battery clusters corresponding to the same PCS power module is allocated.

5. The high-voltage cascaded energy storage system according to claim 1, characterized in that, The three-level BMS control module further includes a first fault handling unit, wherein the first fault handling unit is configured as follows: Determine the fault level of multiple battery clusters corresponding to the same PCS power module, and determine the comprehensive fault level based on the fault level of each battery cluster; The PCS master control module further includes a second fault handling unit, wherein the second fault handling unit is configured as follows: Based on the comprehensive fault level and fault information of the fault clusters, fault handling is performed on multiple battery clusters.

6. The high-voltage cascaded energy storage system according to claim 1, characterized in that, The three-level BMS control module also includes a differential pressure judgment unit, configured as follows: If the inter-cluster pressure difference is less than or equal to the first pressure difference threshold, it is determined that the inter-cluster pressure difference is within the pressure difference safe range. If the inter-cluster pressure difference is greater than the first pressure difference threshold and less than the second pressure difference threshold, it is determined that the inter-cluster pressure difference is in the pressure difference equilibrium range. If the inter-cluster pressure difference is greater than or equal to the second pressure difference threshold, the inter-cluster pressure difference is determined to be in the pressure difference danger range. The pre-charge control unit is configured to: control the main DC contactor of the slave cluster to close when the inter-cluster pressure difference is within the safe range of the pressure difference, so as to pre-charge the slave battery cluster; and control the circulating contactor of the slave cluster to close when the inter-cluster pressure difference is within the range of the pressure difference that can be balanced, so as to adjust the inter-cluster pressure difference.

7. The high-voltage cascaded energy storage system according to claim 1, characterized in that, The PCS master control module also includes a balance control unit, which is configured as follows: Based on the preset total output power of the energy storage system and the SOC deviation ratio of each battery stack, the inter-stack equalization adjustment is performed on multiple battery stacks. Based on the active power of the PCS and the SOC deviation ratio of each phase battery cluster in the three-phase battery cluster, phase-to-phase equalization adjustment is performed on multiple battery stacks, wherein each phase battery cluster includes at least one of the PCS power modules. The PCS master control module also includes an inter-stack equalization safety control unit, wherein the inter-stack equalization safety control unit is configured to: monitor the operating data of each battery stack during the inter-stack equalization adjustment process, and perform equalization safety control based on the operating data of the battery stack. The secondary BMS control module is configured to monitor the operating data of each battery cluster during the process of inter-stack equalization and inter-phase equalization adjustment, and to perform equalization safety control based on the operating data of the battery cluster.

8. The high-voltage cascaded energy storage system according to claim 1, characterized in that, The PCS master control module also includes an auxiliary control unit configured to adjust the environmental parameters of the energy storage system, wherein the environmental parameters include at least one of temperature, humidity and light intensity.

9. A control method for a high-voltage cascaded energy storage system, characterized in that, This invention relates to a high-voltage cascaded energy storage system, comprising a battery management system (BMS) and an energy storage converter. The BMS includes a first-level BMS control module, a second-level BMS control module, and a third-level BMS control module connected sequentially from bottom to top. The energy storage converter includes a PCS master control module and multiple PCS power modules. The first-level BMS control module communicates with the second-level BMS control module via a CAN bus. The second-level BMS control module communicates with the third-level BMS control module via an optical fiber. The PCS master control module communicates with the third-level BMS control module via an Ethernet and / or CAN bus. The PCS master control module communicates with the PCS power modules via the optical fiber. The PCS power modules are also connected to the second-level BMS control modules, and each PCS power module is connected to at least two second-level BMS control modules. At least one of the multiple secondary BMS control modules connected to the same PCS power module is connected to the main battery cluster, and at least one of the multiple secondary BMS control modules is connected to the slave battery cluster; the main battery cluster includes a main cluster precharge contactor and a main cluster main DC contactor, and the slave battery cluster includes a slave cluster main DC contactor and a slave cluster circulating current contactor; the main cluster precharge contactor, the main cluster main DC contactor, the slave cluster main DC contactor, and the slave cluster circulating current contactor are respectively connected to the PCS master control module; The PCS master control module includes a pre-charge control unit. The method includes: In response to the control strategy of the secondary BMS control module, the operation of at least one battery pack is controlled by the primary BMS control module. In response to the control strategy of the three-level BMS control module, the operation of at least one battery cluster is controlled by the two-level BMS control module. In response to the control strategy of the PCS master control module, the operation of at least one battery stack is controlled by the three-level BMS control module, and multiple three-level BMS control modules are coordinated and controlled by the PCS master control module. The PCS master control module coordinates the control of multiple secondary BMS control modules connected to the same PCS power module. The coordinated control of multiple secondary BMS control modules connected to the same PCS power module by the PCS master control module includes: controlling the main cluster precharge contactor to close to precharge the main battery cluster through the precharge control unit of the PCS master control module, and controlling the main cluster main DC contactor according to the precharge result to control the operation of the main battery cluster; after the main battery cluster is powered on, the precharge control unit controls the slave cluster main DC contactor and the slave cluster circulating current contactor based on the inter-cluster voltage difference between the main battery cluster and the slave battery cluster to control the operation of the slave battery cluster.

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