High-voltage energy storage system based on modular multilevel converter

Abstract

The invention relates to the field of power electronic energy storage, and discloses a high-voltage energy storage system based on a modular multilevel converter, which comprises three upper bridge arms and three lower bridge arms, and is characterized in that each bridge arm comprises a battery cluster, a high-voltage box, a power sub-module and a series reactor; each battery cluster is connected with one power sub-module through the high-voltage box, and each power sub-module only corresponds to one battery cluster; the power sub-modules are sequentially connected in series to form a series circuit; the tail ends of the series circuits are connected in series with the reactors to form one bridge arm, the upper bridge arm and the lower bridge arm form one phase, the head ends of the series circuits of the three upper bridge arms are connected together to serve as the positive electrode of the common direct current system, and the tail ends of the series circuits of the three lower bridge arms are connected together to serve as the negative electrode of the common direct current system. According to the invention, the problems of high insulation and voltage resistance requirements are solved, the flexibility and safety of system design and the precision of fault processing are improved, and the system is suitable for different voltage levels and capacity requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronic energy storage, and particularly relates to a high-voltage energy storage system based on a modular multilevel converter. Background Art

[0002] With the acceleration of energy transformation, the problems of intermittency and volatility of new energy power generation have become increasingly prominent. As a key technology to solve this problem, new energy storage has huge market demand. Common energy storage forms include pumped-storage energy storage, electrochemical energy storage, compressed air energy storage, molten salt energy storage, etc. Electrochemical energy storage has gradually occupied an important position in the market with its advantages of high efficiency, fast response, high flexibility, and short construction period, and has formed an effective complement to mechanical energy storage and thermal energy storage. Currently, in the field of new energy photovoltaic and wind power, configuring an electrochemical energy storage system has become a standard configuration, which can play roles such as smoothing power output, improving energy utilization efficiency, and enhancing the stability of the power system.

[0003] Currently, the mainstream high-voltage electrochemical energy storage system adopts a centralized form, where a single energy storage converter device is connected to multiple battery clusters on the DC side. Although the structure is simple, it has several disadvantages, mainly including: First, connecting multiple battery clusters together easily leads to limited system performance, affecting the overall lifespan and economic benefits; Second, due to the inconsistent depth of discharge between different battery clusters, a circulating current phenomenon occurs, which in turn affects the charge and discharge efficiency and may pose a safety risk; Third, the centralized energy storage system has a relatively large single capacity, and the design of sharing a set of fire protection systems for multiple battery clusters has certain safety hazards. Once a single cluster experiences thermal runaway, it is extremely easy to spread to the entire cabinet, potentially triggering a large-scale fire; Fourth, once a failure occurs, usually professional personnel need to be on-site for debugging and maintenance, increasing the downtime and operation and maintenance costs, etc.

[0004] Another form of energy storage system design is the high-voltage direct connection type, which adopts a modular cascaded structure and can directly boost the voltage of the energy storage system to 35 kV. Each power unit module corresponds to a group of batteries. The advantages are that it reduces the use of transformers, simplifies the system structure, and reduces energy losses, and is suitable for high-altitude areas. The disadvantages are: First, the technology is complex, with high requirements for power electronic devices, requiring higher overload capacity and more complex control system design; Second, there are application limitations, and it is not flexible enough for the application of general small-scale energy storage systems; Third, the cost is relatively high, and the safety issues are relatively prominent, etc.

[0005] There is also a string - type energy storage system. The energy storage converter part of it is composed of multiple low - voltage power modules connected in parallel and then stepped up by a step - up transformer. Each power module corresponds to a battery cluster. Compared with the centralized energy storage system, the advantage of the string - type energy storage system is that it adopts a modular design. Each battery cluster is independently controlled for charge and discharge, avoiding the circulating current problem and further improving the conversion efficiency of the system. Each energy storage unit can be independently controlled and managed, which enables the system to be flexibly expanded or supplemented according to actual needs. When a fault occurs, the faulty components can be quickly replaced, shortening the system downtime and reducing the operation and maintenance costs. The disadvantage is that compared with the centralized type, the integration and commissioning of the string - type system may be more complex, and due to the use of more optimizers and monitoring devices, the overall cost of the string - type system may be higher. Summary of the Invention

[0006] Aiming at the above - mentioned existing technical deficiencies, the technical problem to be solved by the present invention is to provide a high - voltage energy storage system based on a modular multilevel converter, aiming to solve the problems of high insulation and withstand voltage requirements for the power sub - module conversion circuit and the battery cluster.

[0007] To solve the above - mentioned technical problems, the present invention adopts the following technical solutions: The present invention provides a high - voltage energy storage system based on a modular multilevel converter, including: Three upper bridge arms and three lower bridge arms. Each bridge arm includes n battery clusters, n high - voltage boxes, n power sub - modules and 1 series reactor; The battery cluster is composed of multiple battery modules connected in series, and a single battery module is composed of several battery cells through series - parallel connection; Each battery cluster is connected to a corresponding power sub - module through the high - voltage boxes on both sides, and each power sub - module corresponds to only one battery cluster; n power sub - modules are connected in series in sequence to form a power sub - module series circuit; The tail end of the power sub - module series circuit is connected with a series reactor to form one of the bridge arms. The upper and lower two bridge arms form a phase. The heads of the power sub - module series circuits of the three upper bridge arms are connected together as the positive pole of the common DC system, and the tails of the power sub - module series circuits of the three lower bridge arms are connected together as the negative pole of the common DC system.

[0008] Further, the power sub - module circuit adopts a half - bridge circuit; The half - bridge circuit includes IGBT - T1, IGBT - T2 and capacitor C1; Both IGBT - T1 and IGBT - T2 adopt IGBTs with anti - parallel diodes; One end of the capacitor C1 is connected to the collector of IGBT - T1 as one end of the power sub - module input. The emitter of IGBT - T1 is respectively connected to the collector of IGBT - T2 and one end of the power sub - module output; The other end of the capacitor C1 is respectively connected to the emitter of the IGBT-T2 and one end of the output of the power sub-module as the other end of the input of the power sub-module.

[0009] Furthermore, the power sub-module circuit adopts a full-bridge circuit; The full-bridge circuit includes IGBT-T3, IGBT-T4, IGBT-T5, IGBT-T6 and capacitor C2; the IGBT-T3, IGBT-T4, IGBT-T5, IGBT-T6 all adopt IGBTs with anti-parallel diodes; One end of the capacitor C2 is respectively connected to the collector of the IGBT-T3, the collector of the IGBT-T5 as one end of the input of the power sub-module, and the emitter of the IGBT-T3 and the collector of the IGBT-T4 are connected as one end of the output of the power sub-module; The other end of the capacitor C2 is respectively connected to the emitter of the IGBT-T4 and the emitter of the IGBT-T6 as the other end of the input of the power sub-module; The emitter of the IGBT-T5 and the collector of the IGBT-T6 are connected as the other end of the output of the power sub-module.

[0010] Furthermore, it also includes an energy storage main control unit and a sub-control unit integrated in each power sub-module; The energy storage main control unit receives the superior dispatching instruction, calculates the modulation wave parameters for each power sub-module according to the overall operation requirements of the system, and the calculated modulation wave parameters are sent to each sub-control unit through the optical fiber network. Each sub-control unit generates the corresponding IGBT pulse control signal based on the received modulation wave parameters and the locally generated triangular carrier signal.

[0011] The sub-control unit is also responsible for monitoring the status information of the power sub-module where it is located, and sending a fault signal to the control host when an abnormality is detected.

[0012] Furthermore, generating the corresponding IGBT pulse control signal by comparing the sine modulation wave with the triangular carrier signal includes: The phase of the sine wave modulation wave signals between phases is mutually different by 120 degrees, and the phase between the upper and lower arm sine wave modulation wave signals in each phase is mutually different by 180 degrees; For each power sub-module at the corresponding position of each phase, the same triangular carrier signal with a fixed phase difference is adopted, and the fixed phase difference is equal to 360 degrees divided by the number of power sub-modules in the current bridge arm; Compare the upper and lower arm sine wave modulation wave signals in each phase with the triangular carrier signals corresponding to each power sub-module to generate the corresponding IGBT pulse control signal for each power sub-module.

[0013] Furthermore, the interior of the high-voltage box includes a smoothing reactor, a fuse, and a pre-charging device; The ports of the high-voltage box include a first connector, a second connector, a third connector, a fourth connector, an RS485 communication port, an alarm port, a protection port, a 24V power supply port, and a communication interface BCMS. Among them, the first connector and the second connector are connected to the DC side of the power sub-module through a copper bar, and the third connector and the fourth connector are connected to the battery cluster through a DC cable; The RS485 communication port transmits information such as the maximum charging current of the battery, the maximum discharging current of the battery, the battery fault alarm status, the highest battery temperature, SOC, and SOH of the corresponding battery cluster to the sub-control unit of the power sub-module.

[0014] Furthermore, it also includes a three-level BMS system that communicates with the energy management system EMS; The three-level BMS system includes a BMU system, a BCMS system, and a BAMS system; Among them, each battery module corresponds to a BMU system, which is used to monitor and manage the battery cells in real time to ensure the safe operating state of each battery cell and provide data support for the upper-level BCMS system; Each battery cluster is composed of multiple battery modules connected in parallel. Each battery cluster corresponds to a BCMS system, and at the same time each power sub-module corresponds to a BCMS system. The BCMS system communicates with the BMU systems corresponding to each battery module in the cluster through the CAN bus, and is used to realize data acquisition, advanced control, and fault diagnosis to ensure the safe and efficient operation of the battery cluster; Each arm corresponds to a BAMS system. Each arm includes n power sub-modules. The n BCMS systems in each arm communicate with the BAMS system corresponding to the arm through a ring network; After multiple BAMS systems are connected through a ring network, they are connected to the energy management system EMS system of the energy storage system through a dual network; The energy storage main control unit communicates with each BAMS system to realize all-round monitoring and protection of the entire battery system.

[0015] The beneficial effects of the present invention are as follows: 1. The entire high-voltage energy storage system forms two virtual common points, the positive busbar and the negative busbar points, which can ensure the balance of the phase-to-phase voltage, and further ensure the voltage balance between each battery cluster, thereby extending the battery life; 2. Sampling the DC bus voltage values of all modules, summing them up and taking the average, instead of directly sampling the voltage value between the positive and negative busbars, as the control target, greatly simplifies the control system; 3. Based on the phase relationship between the three phases of ABC and the relationship between the upper and lower bridge arms, the pulse signals of all power sub-module IGBTs are obtained based on carrier phase-shifted SPWM, and the generation process is simple and efficient; 4. Adopting a modular multi-level structure can, on the one hand, achieve the integration of a larger-capacity energy storage system, and on the other hand, reduce the insulation performance requirements for power sub-modules, thereby reducing the complexity of system design; 5. Adopting a modular design structure and establishing a one-to-one communication relationship between each power sub-module and the battery cluster can quickly obtain battery-related parameter information, reduce data delay, improve the dynamic response speed of the system, and provide fast protection during faults. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0017] Figure 1 It is the main circuit diagram of a high-voltage energy storage system based on a modular multi-level converter provided by an embodiment of the present invention.

[0018] Figure 2 It is the half-bridge circuit structure diagram of the power sub-module.

[0019] Figure 3 It is the full-bridge circuit structure diagram of the power sub-module.

[0020] Figure 4 It is the process schematic diagram for generating the corresponding IGBT pulse control signal.

[0021] Figure 5 It is the working principle diagram of the high-voltage box.

[0022] Figure 6 It is the communication topology diagram of a high-voltage energy storage system based on a modular multi-level converter of the present invention. Detailed Embodiments

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. Embodiment

[0024] Since the modular multilevel converter (MMC) is currently widely used in flexible DC transmission systems, compared with traditional two-level and three-level converters, MMC can be flexibly extended to high voltage and high power by increasing the number of modules. Moreover, its power components can operate at a lower switching frequency, with extremely high conversion efficiency, very small voltage and current spikes, and very low harmonic content in the output voltage, etc.

[0025] Therefore, in this embodiment, a new circuit topology diagram of an energy storage system is obtained based on the MMC topology. This patent combines the advantages of centralized energy storage systems, directly-connected energy storage systems, and string-type energy storage systems. It adopts a modular design structure, which can realize one-to-one control of each unit module and battery cluster, achieving one-cluster-one management, and avoiding the circulating current problem caused by the parallel connection of battery clusters on the DC side of the centralized energy storage. Compared with the string-type, there is no step-up transformer, the system cost is lower, the system integration degree is higher with the prefabricated cabin design structure, and the control response speed is faster. Compared with the direct connection method using the MMC topology, it reduces the insulation performance requirements of each unit module, the system is easier to design and implement, and at the same time, it can achieve AC output at a higher voltage level and larger-scale energy storage system integration. The entire system operates flexibly and is particularly suitable for the design and application of large-capacity energy storage power stations.

[0026] Specifically, as Figures 1-6 shown, this embodiment provides a high-voltage energy storage system based on a modular multilevel converter, including: As Figure 1 shown, there are three upper bridge arms and three lower bridge arms. Each bridge arm includes n battery clusters, n high-voltage boxes, n power sub-modules, and 1 series reactor; the battery cluster is composed of multiple battery modules connected in series, and a single battery module is composed of several battery cells through series-parallel connection; each battery cluster is connected to a corresponding power sub-module through the high-voltage boxes on both sides, and each power sub-module only corresponds to one battery cluster; the n power sub-modules are connected in series in sequence to form a power sub-module series circuit; after the tail end of the power sub-module series circuit is connected in series with the reactor, it forms one of the bridge arms. The upper and lower two bridge arms form a phase. The heads of the power sub-module series circuits of the three upper bridge arms are connected together as the positive pole of the common DC system, and the tails of the power sub-module series circuits of the three lower bridge arms are connected together as the negative pole of the common DC system. The midpoints of the three-phase bridge arms are led out to connect the ABC three phases of the power grid, which can solve the problems of high insulation and withstand voltage requirements for the power sub-module conversion circuit and battery cluster. At the same time, the carrier phase-shifted pulse control method is used to generate pulse signals of 6n modules, improving the equivalent switching frequency of the entire system, reducing the harmonic content of the grid-connected current, and also only requiring a very small series reactor, reducing the system cost.

[0027] As Figure 2As shown in the figure, the power sub-module circuit adopts a half-bridge circuit, which includes IGBT-T1, IGBT-T2, and capacitor C1; both IGBT-T1 and IGBT-T2 use IGBTs with anti-parallel diodes; one end of capacitor C1, as one end of the power sub-module input, is connected to the collector of IGBT-T1, and the emitter of IGBT-T1 is respectively connected to the collector of IGBT-T2 and one end of the power sub-module output; the other end of capacitor C1, as the other end of the power sub-module input, is respectively connected to the emitter of IGBT-T2 and one end of the power sub-module output.

[0028] As Figure 3 shown in the figure, the power sub-module circuit adopts a full-bridge circuit; the full-bridge circuit includes IGBT-T3, IGBT-T4, IGBT-T5, IGBT-T6, and capacitor C2; IGBT-T3, IGBT-T4, IGBT-T5, and IGBT-T6 all use IGBTs with anti-parallel diodes; one end of capacitor C2, as one end of the power sub-module input, is also respectively connected to the collector of IGBT-T3 and the collector of IGBT-T5, and the emitter of IGBT-T3 and the collector of IGBT-T4 are connected as one end of the power sub-module output; the other end of capacitor C2, as the other end of the power sub-module input, is respectively connected to the emitter of IGBT-T4 and the emitter of IGBT-T6; the emitter of IGBT-T5 and the collector of IGBT-T6 are connected as the other end of the power sub-module output.

[0029] Preferably, the high-voltage energy storage system of the present invention further includes an energy storage main control unit and a sub-control unit integrated in each power sub-module; the energy storage main control unit receives the superior dispatching instruction, calculates the modulation wave parameters for each power sub-module according to the overall operation requirements of the system, and the calculated modulation wave parameters are sent to each sub-control unit through the optical fiber network. Each sub-control unit generates corresponding IGBT pulse control signals based on the received modulation wave parameters and the triangular carrier signals generated locally; the sub-control unit is also responsible for monitoring the status information of the power sub-module where it is located and sending a fault signal to the control host when an abnormality is detected.

[0030] As Figure 4 shown in the figure, the corresponding IGBT pulse control signals are generated by comparing the sine modulation wave with the triangular carrier signal. In the figure, m1 and m2 are the sine wave modulation wave signals corresponding to the upper and lower bridge arms respectively, and the phases of the sine wave modulation wave signals differ by 180 degrees. a1, a2... an are the triangular carrier signals corresponding to each power sub-module of the upper bridge arm, and b1, b2... bn are the triangular carrier signals corresponding to each power sub-module of the lower bridge arm. The phases of the triangular carrier signals differ from each other by 360° / n.

[0031] The phase differences between the sine modulation wave signals of phases A, B, and C are 120 degrees from each other. The power sub-modules at the corresponding positions of phases A, B, and C use the same triangular carrier signal, and the switching signal of each power sub-module is generated by comparing the sine modulation wave with the triangular carrier signal. According to the phase relationship between the three phases of ABC and the relationship between the upper and lower bridge arms, the present invention obtains the pulse control signals of the IGBTs of all power sub-modules based on carrier phase-shifted SPWM, and the generation process is simple and efficient.

[0032] Specifically, as Figure 5 shown, in the figure, 1+ represents the first connector, 1- represents the second connector, 2+ represents the third connector, and 2- represents the fourth connector. Specifically, the high-voltage box internally includes a smoothing reactor, a fuse, and a pre-charging device; the high-voltage box ports include the first connector, the second connector, the third connector, the fourth connector, an RS485 communication port, an alarm port, a protection port, a 24V power supply port, and a communication interface BCMS. Among them, the first connector and the second connector are connected to the DC side of the power sub-module through a copper bar, and the third connector and the fourth connector are connected to the battery cluster through a DC cable; the RS485 communication port transmits the battery maximum charging current, battery maximum discharging current, battery fault alarm status, battery maximum temperature, SOC, and SOH information of the corresponding battery cluster to the sub-control unit of the power sub-module, realizing the status monitoring and rapid protection of the battery cluster by each power sub-module, and ensuring the one-to-one correspondence between each power sub-module and the battery cluster.

[0033] Preferably, as Figure 6 shown, the entire energy storage system of the present invention further includes a three-level BMS system communicating with the energy management system EMS; the three-level BMS system includes a BMU system, a BCMS system, and a BAMS system; among them, each battery module corresponds to a BMU system, which is used to monitor and manage the battery cells in real time to ensure the safe operation state of each battery cell and provide data support for the upper-layer BCMS system; each battery cluster is composed of multiple parallel-connected battery modules, each battery cluster corresponds to a BCMS system, and at the same time each power sub-module corresponds to a BCMS system. The BCMS system communicates with the BMU systems corresponding to the battery modules in the cluster through the CAN bus, and is used to realize data acquisition, advanced control, and fault diagnosis to ensure the safe and efficient operation of the battery cluster; each bridge arm corresponds to a BAMS system, each bridge arm includes n power sub-modules, and the n BCMS systems in each bridge arm communicate with the BAMS system corresponding to the bridge arm through a ring network; after the multiple BAMS systems are connected through a ring network, they are connected to the energy management system EMS system of the energy storage system through a dual network; the energy storage main control unit communicates with each BAMS system to realize the omnidirectional monitoring and protection of the entire battery system.

[0034] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-voltage energy storage system based on a modular multilevel converter, characterized in that Comprising: Three upper bridge arms and three lower bridge arms, each bridge arm including n battery clusters, n high-voltage boxes, n power sub-modules and 1 series reactor; the battery clusters are composed of a plurality of battery modules connected in series, and a single battery module is composed of several battery cells through series and parallel connections; each battery cluster is connected to a corresponding power sub-module through the high-voltage boxes on both sides, and each power sub-module corresponds to only one battery cluster; the n power sub-modules are connected in series in sequence to form a power sub-module series circuit; the tail end of the power sub-module series circuit is connected with a series reactor to form one of the bridge arms, and the upper and lower two bridge arms form a phase. The heads of the power sub-module series circuits of the three upper bridge arms are connected together as the positive pole of the common DC system, and the tails of the power sub-module series circuits of the three lower bridge arms are connected together as the negative pole of the common DC system.

2. The high-voltage energy storage system based on a modular multilevel converter according to claim 1, wherein The power sub-module circuit adopts a half-bridge circuit; The half-bridge circuit includes IGBT-T1, IGBT-T2 and capacitor C1; both IGBT-T1 and IGBT-T2 adopt IGBTs with anti-parallel diodes; One end of capacitor C1, as one end of the power sub-module input, is connected to the collector of IGBT-T1, and the emitter of IGBT-T1 is respectively connected to the collector of IGBT-T2 and one end of the power sub-module output; The other end of capacitor C1, as the other end of the power sub-module input, is respectively connected to the emitter of IGBT-T2 and one end of the power sub-module output.

3. The high-voltage energy storage system based on a modular multilevel converter according to claim 1, characterized in that, The power sub-module circuit adopts a full-bridge circuit; The full-bridge circuit includes IGBT-T3, IGBT-T4, IGBT-T5, IGBT-T6 and capacitor C2; IGBT-T3, IGBT-T4, IGBT-T5, and IGBT-T6 all adopt IGBTs with anti-parallel diodes; One end of capacitor C2, as one end of the power sub-module input, is also respectively connected to the collector of IGBT-T3 and the collector of IGBT-T5. The emitter of IGBT-T3 and the collector of IGBT-T4 are connected as one end of the power sub-module output; The other end of capacitor C2, as the other end of the power sub-module input, is respectively connected to the emitter of IGBT-T4 and the emitter of IGBT-T6; The emitter of IGBT-T5 and the collector of IGBT-T6 are connected as the other end of the power sub-module output.

4. The high-voltage energy storage system based on a modular multilevel converter according to claim 1, wherein It also includes an energy storage main control unit and a sub-control unit integrated in each power sub-module; The energy storage main control unit receives the superior dispatching instruction, calculates the modulation wave parameters for each power sub-module according to the overall operation requirements of the system, and the calculated modulation wave parameters are sent to each sub-control unit through the optical fiber network. Each sub-control unit generates corresponding IGBT pulse control signals based on the received modulation wave parameters and the locally generated triangular carrier signals; The sub-control unit is also responsible for monitoring the status information of the power sub-module where it is located and sending a fault signal to the control host when an abnormality is detected.

5. The high-voltage energy storage system based on a modular multilevel converter according to claim 1, wherein Generating the corresponding IGBT pulse control signal by comparing the sine modulation wave with the triangular carrier signal includes: The phase of the sine wave modulation wave signals between phases is mutually different by 120 degrees, and the phase between the upper and lower arm sine wave modulation wave signals in each phase is mutually different by 180 degrees; For the power sub-modules at corresponding positions of each phase, the same triangular carrier signals with a fixed phase difference are adopted, and the fixed phase difference is equal to 360 degrees divided by the number of power sub-modules in the current arm; Compare the upper and lower arm sine wave modulation wave signals in each phase with the corresponding triangular carrier signals of each power sub-module to generate the corresponding IGBT pulse control signals for each power sub-module.

6. The high-voltage energy storage system based on a modular multilevel converter according to claim 1, characterized in that The high-voltage box internally includes a smoothing reactor, a fuse, and a pre-charging device; The high-voltage box ports include a first connector, a second connector, a third connector, a fourth connector, an RS485 communication port, an alarm port, a protection port, a 24V power supply port, and a communication interface BCMS. Among them, the first connector and the second connector are connected to the DC side of the power sub-module through a copper bar, and the third connector and the fourth connector are connected to the battery cluster through a DC cable; The RS485 communication port transmits the battery maximum charging current, battery maximum discharging current, battery fault alarm status, battery highest temperature, SOC, and SOH information of the corresponding battery cluster to the sub-control unit of the power sub-module.

7. The high-voltage energy storage system based on a modular multilevel converter according to claim 4, characterized in that, It further includes a three-level BMS system communicating with the energy management system EMS; The three-level BMS system includes a BMU system, a BCMS system, and a BAMS system; Among them, each battery module corresponds to a BMU system, which is used to monitor and manage the battery cells in real time to ensure the safe operating state of each battery cell and provide data support for the upper-layer BCMS system; Each battery cluster is composed of multiple battery modules connected in parallel. Each battery cluster corresponds to a BCMS system, and at the same time each power sub-module corresponds to a BCMS system. The BCMS system communicates with the BMU systems corresponding to each battery module in the cluster through the CAN bus, and is used to realize data acquisition, advanced control, and fault diagnosis to ensure the safe and efficient operation of the battery cluster; Each arm corresponds to a BAMS system. Each arm includes n power sub-modules. The n BCMS systems in each arm communicate with the BAMS system corresponding to the arm through a ring network; After multiple BAMS systems are connected through a ring network, they are connected to the energy management system EMS system of the energy storage system through a dual network; The energy storage main control unit communicates with each BAMS system to achieve comprehensive monitoring and protection of the entire battery system.

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