Energy storage system direct current side control architecture and control method

Abstract

The invention relates to an energy storage system direct current side control architecture and a control method. The energy storage system direct current side control architecture comprises an energy storage unit, a PCS unit and a BCU unit. A positive pole main switch device and a pre-charging switch unit are arranged in parallel between the positive end of the energy storage unit and the positive end of the PCS unit, and the pre-charging switch unit comprises a pre-charging switch device and a pre-charging resistor which are connected in series; a negative electrode main switch device is arranged between the negative end of the energy storage unit and the negative end of the PCS unit; a PCS control unit of the PCS unit is used for controlling the on-off of a positive pole main switching device and a pre-charging switching device; and the BCU control unit of the BCU unit is used for controlling the on-off of the negative electrode main switch device. According to the invention, the BCU controls the on-off of the negative electrode main switch device, and the PCS controls the on-off of the positive electrode main switch device and the pre-charging switch device, so that the fault response speed and the isolation precision are improved, the diagnosis and positioning of the system fault are more direct and clear, and the overall reliability and maintainability of the system are further enhanced.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, and in particular to a DC-side control architecture and control method for an energy storage system. Background Technology

[0002] With the deepening of the global energy transition, energy storage systems, as a key technology for renewable energy consumption and grid stability, are receiving increasing attention for their safety, reliability, and efficiency. In traditional centralized control architectures, relays are typically managed by a power storage converter (PCS), and the battery management system (BCU) often lacks the ability to directly disconnect the main circuit.

[0003] This centralized architecture has the following main drawbacks in practical applications: First, the control of switching devices is centralized, and a PCS failure or control link failure will lead to DC side uncontrollability, and the timing control flexibility is insufficient and the safety redundancy is poor; Second, the startup and self-test processes are serial and rely on the PCS for overall coordination, resulting in slow response speed and failing to meet the requirements of fast response scenarios; Third, the communication architecture between the PCS, BCU and the upper-level power management system (PMU) is complex, with the risk of delay and packet loss, and low reliability of coordination in the event of a failure.

[0004] In summary, the existing centralized architecture is difficult to adapt to the development needs of industrial and commercial energy storage systems. Developing DC-side control solutions that can improve redundancy, response speed, and collaborative reliability has become an urgent problem to be solved in the industry. Summary of the Invention

[0005] This application provides a DC-side control architecture and control method for an energy storage system. The BCU control unit controls the switching on and off of the negative main switching device, and the PCS control unit controls the switching on and off of the positive main switching device and the pre-charge switching device, which can achieve rapid fault isolation and precise protection.

[0006] In a first aspect, this application provides a DC-side control architecture for an energy storage system, including an energy storage unit, a PCS unit, and a BCU unit;

[0007] A positive main switch device and a pre-charge switch unit are provided in parallel between the positive terminal of the energy storage unit and the positive terminal of the PCS unit. The pre-charge switch unit includes a pre-charge switch device and a pre-charge resistor connected in series. A negative main switch device is provided between the negative terminal of the energy storage unit and the negative terminal of the PCS unit. The PCS control unit of the PCS unit is configured to control the on / off state of the positive main switch device and the precharge switch device, so as to realize the orderly connection between precharge and main power transmission. The BCU control unit of the BCU unit is configured to control the on / off state of the negative main switching device.

[0008] Furthermore, the first end of the positive main switch device and the first end of the pre-charge switch unit are connected to the same terminal on the positive end of the energy storage unit; The second terminal of the positive main switch device and the second terminal of the precharge switch unit are connected to the same terminal on the positive end of the PCS unit.

[0009] Furthermore, the DC-side control architecture of the energy storage system in this application also includes a PMU power management unit. The PMU power management unit is communicatively connected to the BCU control unit and the PCS control unit, respectively. It is configured to receive the energy storage unit status information reported by the BCU control unit and the grid-side status information reported by the PCS control unit, issue global coordination commands to the BCU control unit and the PCS control unit, and synchronously trigger the disconnection action of the positive and negative main switching devices under fault conditions.

[0010] Furthermore, the BCU control unit and the PCS control unit are communicatively connected, and the two control units are configured to independently trigger the disconnection protection action of the corresponding side switching device based on their own monitoring status when a fault condition is detected.

[0011] On the other hand, this application also provides a DC-side control method for an energy storage system, applicable to the DC-side control architecture of the energy storage system described in any of the above claims, comprising the following steps: S1. In response to the system startup command, the BCU unit and the PCS unit perform power-on self-test in parallel; S2. If both the BCU unit and the PCS unit pass the self-test, proceed to step S3; if any unit fails the self-test, terminate the startup process. S3. The BCU control unit controls the negative main switch device to close and detects the closing status of the negative main switch device; S4. If the negative main switch device is successfully closed, the BCU control unit sends the closing status information of the negative main switch device to the PCS control unit and executes step S5. S5. In response to receiving the closing status information of the negative main switch device, the PCS control unit controls the pre-charge switch device to close and monitors the DC bus voltage; S6. If the DC bus voltage reaches a preset threshold within a preset time, the PCS control unit controls the positive main switch device to close and executes step S7. S7. The PCS control unit detects the closed state of the positive main switch device; S8. If the positive main switch device closes successfully, after confirming that the positive main switch device is stably conducting, control the precharge switch device to open and complete the system startup.

[0012] Furthermore, step S4 also includes: if the negative main switch fails to close, the BCU control unit reports the fault to the PMU power management unit and terminates the process.

[0013] Furthermore, step S6 also includes: if the DC bus voltage does not reach the preset threshold within a preset time, the PCS control unit reports to the PMU power management unit and terminates the process.

[0014] Furthermore, step S8 also includes: if the positive main switch device fails to close, the PCS control unit reports the fault to the PMU power management unit and terminates the process.

[0015] Furthermore, the DC-side control method of the energy storage system in this application also includes: during operation, when the BCU control unit detects a fault on the energy storage unit side, it controls the disconnection of the negative main switching device and reports the information to the PMU power management unit; The fault information is simultaneously sent to the PCS control unit, triggering the positive main switch device on the PCS unit side to disconnect, thereby achieving rapid isolation at both ends.

[0016] Furthermore, the DC-side control method for the energy storage system in this application also includes: During operation, when the PCS control unit detects a grid-side fault or receives a shutdown command, it controls the disconnection of the positive main switch device and reports the information to the PMU power management unit.

[0017] Compared with existing technologies, the advantages of this invention are as follows: The DC-side control architecture of this energy storage system integrates the Battery Control Unit (BCU) and the Energy Storage Converter Unit (PCS) into a single device, and establishes a clearly defined separation control mode. The BCU unit controls the switching of the negative main switching device, while the PCS unit controls the switching of the positive main switching device and the pre-charge switching device. This control mode achieves proximity isolation of fault sources, forming a targeted power safety protection mechanism. It not only significantly improves the system's fault response speed and isolation accuracy but also makes the fault diagnosis and location process more direct and clear, effectively enhancing the overall operational reliability and maintainability of the energy storage system. Attached Figure Description

[0018] Figure 1 A schematic diagram of the DC-side control architecture of an energy storage system provided in this application embodiment; Figure 2 A schematic diagram illustrating the communication connections between various units of a DC-side control architecture for an energy storage system, provided in an embodiment of this application; Figure 3A flowchart of a DC-side control method for an energy storage system provided in an embodiment of this application. Detailed Implementation

[0019] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Furthermore, the technical features involved in the different embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0022] Example 1 This embodiment provides a DC-side control architecture for an energy storage system, combined with... Figure 1As shown, the circuit includes an energy storage unit, a PCS unit, and a BCU unit. The BCU unit is deployed on the energy storage unit side and is primarily responsible for the management and protection of the energy storage unit. The PCS unit is the core power conversion component that enables bidirectional energy flow between the energy storage system and the power grid. It mainly undertakes the functions of controlling the charging and discharging process of the energy storage battery, converting AC to DC power, and focusing on the conversion of energy form and interaction with the external power grid. This unit consists of core components such as a DC / AC bidirectional converter and a PCS control unit. The PCS control unit receives control commands from the power management unit (PMU) through a communication link and drives the DC / AC bidirectional converter to complete the charging or discharging control of the energy storage unit. Specifically, a positive main switching device and a pre-charge switching unit are connected in parallel between the positive terminal of the energy storage unit and the positive terminal of the PCS unit. The pre-charge switching unit includes a pre-charge switching device and a pre-charge resistor connected in series; a negative main switching device is connected between the negative terminal of the energy storage unit and the negative terminal of the PCS unit. The PCS control unit of the PCS unit is responsible for time-division coordinated control of the on / off states of the positive main switching device and the pre-charge switching device, thereby achieving an orderly connection between the pre-charge stage and the main power transmission stage of the energy storage system. The BCU control unit of the BCU unit is specifically responsible for controlling the on / off state of the negative main switching device.

[0023] This embodiment employs a separate control mode where the BCU control unit dominates the switching of the negative main switching device, and the PCS control unit dominates the switching of the positive main switching device and the pre-charge switching device. This achieves localized control and independent protection. On one hand, the BCU unit is tightly integrated with the battery cluster, enabling direct acquisition and monitoring of key status parameters such as voltage, current, and temperature of the energy storage unit. By delegating control of the negative main switching device to the BCU control unit, direct and rapid protection of the energy storage unit can be achieved. When the BCU control unit detects abnormal conditions such as over-temperature, over-voltage, or individual cell failure in the energy storage unit, it can immediately trigger the negative main switching device to disconnect, isolating the energy storage unit from the DC bus. The entire protection process does not require waiting for commands from other units, significantly shortening the fault response time. On the other hand, the PCS unit, as the system's power conversion unit, directly undertakes the tasks of interactive scheduling and power regulation with the grid. Delegating control of the positive main switching device and the pre-charge switching device to the PCS control unit allows it to respond quickly based on grid operating status, system power demand, and PCS unit fault conditions. When the PCS detects a grid anomaly, circuit overcurrent, or its own fault, it can quickly disconnect the positive main switch device, effectively blocking the fault propagation path, protecting the entire energy storage system from the impact of external grid faults, and improving the overall operational stability of the system.

[0024] Furthermore, in order to achieve the reuse of the positive side hardware interface and power path, and reduce redundant devices and fault points, in this embodiment, the first end of the positive main switch device and the precharge switch unit are connected to the same terminal on the positive end of the energy storage unit, and the second end is connected to the same terminal on the positive end of the PCS unit.

[0025] Furthermore, combined with Figure 2 As shown, the DC-side control architecture of the energy storage system in this embodiment also includes a PMU (Power Management Unit). This unit establishes connections with the BCU (Block Controller Unit) and PCS (Power Control System) units via dry contacts. The BCU and PCS units are also interconnected via dry contacts. These dry contact connections enable rapid transmission of critical status signals. Furthermore, the PMU establishes bidirectional communication connections with the BCU and PCS units via an RS485 communication bus. On one hand, it receives energy storage unit status information reported by the BCU control unit and grid-side status information reported by the PCS control unit. On the other hand, it issues global control commands to the BCU and PCS control units and can synchronously trigger the disconnection of the positive and negative main switching devices in the event of a system fault, ensuring system safety.

[0026] As the central hub for overall coordination, the Power Management Unit (PMU) undertakes the core functions of issuing global commands, summarizing status information, and coordinating control. Firstly, as the initiator of global commands, the PMU uniformly issues core operation commands such as system start-up, shutdown, and grid connection, achieving centralized control of system operations. Secondly, as the status information aggregation center, the PMU collects real-time operating parameters and fault alarms from the BCU and PCS units, providing data support for control decisions. Thirdly, as the coordination and control hub, the PMU dynamically coordinates the action logic of the BCU and PCS units based on the collected system status and external operational requirements, optimizing system operation strategies to achieve efficient and intelligent operation of the energy storage system.

[0027] This embodiment optimizes the control architecture and logic to achieve parallel collaborative work between the BCU unit and the PCS unit, significantly improving system response efficiency. During system startup, the PMU can simultaneously issue startup permission commands to both the BCU and PCS units, allowing them to execute self-test processes in parallel without needing to wait serially across units, effectively shortening system startup time. Furthermore, by combining parallel multiplexing topology and parallel action logic design, the PMU assumes the responsibility of summarizing and distributing global data, transforming the BCU and PCS units from their original interdependent working mode to an independent working mode where each performs its own function. Inter-unit communication serves only as a supplementary means of state synchronization, further enhancing operational independence.

[0028] The system's fault response mechanism has also been significantly optimized: when a system fault is detected, the PMU can simultaneously issue a main switching device disconnection command to both the BCU unit and the PCS unit. The two units do not need to negotiate across units and can independently and quickly execute the disconnection action, which greatly shortens the fault response time and improves the system's fault protection capability.

[0029] Example 2 This embodiment provides a DC-side control method for an energy storage system. Its core lies in achieving safe and stable DC-side startup of the system through the coordinated operation of the BCU unit, PCS unit, and PMU power management unit. Figure 3 As shown, the specific steps include: S1. In response to the system startup command, the BCU unit and the PCS unit perform power-on self-test in parallel. S2. If both the BCU unit and the PCS unit pass the self-test, proceed to step S3. S3, BCU control unit controls the closing of the negative main switch device and detects the closing status of the negative main switch device; S4. If the negative main switch device is successfully closed, the BCU control unit sends the negative main switch device closure status information to the PCS control unit and executes step S5. S5. In response to receiving the closing status information of the negative main switch device, the PCS control unit controls the pre-charge switch device to close and monitors the DC bus voltage; S6. If the DC bus voltage reaches the preset threshold within a preset time, the PCS control unit controls the positive main switch device to close and executes step S7. S7, the PCS control unit detects the closed state of the positive main switch device; S8. If the positive main switch device closes successfully, after confirming that the positive main switch device is stably conducting, control the precharge switch device to open and complete the system startup.

[0030] In steps S1-S8 above, system startup is contingent upon the PMU power management unit issuing a startup permission command. Upon receiving the command, the BCU and PCS units perform power-on self-tests in parallel to prevent system startup anomalies caused by a single unit failure. The self-test covers core hardware (such as driver modules and detection circuits), communication links (with the PMU and other units), etc. Only when both self-test results are qualified is the system allowed to enter the switching device operation stage. Any self-test failure in any unit will directly terminate the process and report a fault, ensuring a safe initial startup state.

[0031] During the switching device operation phase, to avoid DC bus surges and component damage, the switching device closure strictly follows a standardized sequence: negative main switching device → pre-charge switching device → positive main switching device → disconnecting the pre-charge switching device. First, the negative main switching device is closed to establish the negative side of the circuit. Then, the pre-charge switching device connects to the pre-charge circuit, slowly increasing the DC bus voltage to a safe range. This avoids a large current surge due to excessive voltage difference when the positive main switching device closes directly. Finally, the pre-charge switching device is disconnected to complete the normal operating circuit switching. Specifically, after a successful self-test, the BCU control unit controls the negative main switching device to close and detects its closing status. If the negative main switching device closes successfully, the BCU control unit sends the closing status information to the PCS control unit; if the negative main switching device fails to close (e.g., contact adhesion, failure to engage), a fault is immediately reported to the PMU power management unit, and the process is terminated. Upon receiving the negative main switch's closing status information, the PCS control unit initiates a time-sharing coordinated control program. It first controls the pre-charge switch to close, while simultaneously monitoring the DC bus voltage changes via a voltage acquisition module. If the DC bus voltage reaches a preset threshold within a preset time, the PCS control unit then controls the positive main switch to close and detects its closing status. If the DC bus voltage does not reach the preset threshold within the preset time, it indicates an anomaly in the pre-charge circuit. The PCS control unit reports this to the PMU power management unit and terminates the process. If the positive main switch closes successfully, the PCS control unit, after confirming stable conduction, controls the pre-charge switch to open, completing system startup. If the positive main switch fails to close, the PCS control unit reports a fault to the PMU power management unit and terminates the process.

[0032] In this embodiment, the control method involves coordinated operation of each unit, with each unit performing its specific function. The BCU control unit is responsible for driving and monitoring the status of the negative main switch device, ensuring the reliable construction of the negative circuit. The PCS control unit assumes core control responsibilities, uniformly driving the positive main switch device and the pre-charge switch device, and precisely executing the complete process of pre-charge, voltage matching, main circuit closure, and pre-charge disconnection through a time-sharing coordinated control program. It is also responsible for key aspects such as bus voltage monitoring and positive main switch device status confirmation. The PMU power management unit plays a global management role, responsible for issuing start-up permits, receiving fault information, and recording fault logs, providing a basis for subsequent fault troubleshooting. A clear fault detection and reporting mechanism is set up for each stage from the self-test phase to the operation of the switch devices. Whether it is a self-test anomaly, a switch device failure to close, insufficient pre-charge voltage, or unstable contact conduction, the start-up process will be immediately terminated and specific fault information will be reported to prevent the fault from escalating and to ensure the safety of system equipment and personnel.

[0033] During system operation, when the BCU control unit detects a fault on the energy storage unit side, it will immediately control the disconnection of the negative main switch device and simultaneously report the fault information to the PMU power management unit. This fault information will also be simultaneously sent to the PCS control unit, triggering the PCS control unit to disconnect the positive main switch device, thus achieving rapid isolation at both ends. As the direct manager of the energy storage unit, the BCU unit can detect fault signals and respond immediately when an abnormality occurs in the energy storage unit. For example, when the BCU unit detects that the energy storage unit temperature exceeds the safety threshold, it will immediately trigger an over-temperature alarm and perform a load reduction operation. If the temperature continues to rise, the BCU unit can independently disconnect the negative main switch device, isolating the energy storage unit from the DC bus to prevent thermal runaway from spreading between battery clusters. The fault information will be simultaneously sent to the PCS control unit, triggering the disconnection of the positive main switch device on the PCS unit side, achieving rapid isolation at both ends.

[0034] When the PCS control unit detects a grid-side fault or receives a shutdown command, it will quickly disconnect the positive main switch and report the fault / operation information to the PMU power management unit. The PCS unit has comprehensive protection functions, including overcurrent protection, overvoltage protection, and short-circuit protection. It can monitor AC and DC current parameters in real time. Once the output current exceeds a preset safety threshold, it will immediately trigger protection actions, ensuring the system's rapid isolation capability in the face of external faults. For example, when the PCS unit detects a grid anomaly, overcurrent, or other power-side fault, it can immediately disconnect the positive main switch, cutting off the fault propagation path and preventing the fault from spreading to other parts of the system.

[0035] In summary, this invention employs a separate control method where the BCU unit dominates the negative main switching device and the PCS unit dominates the positive main switching device. This method offers significant technical advantages in power safety protection, control execution efficiency, and fault emergency response. The BCU unit, as the direct manager of the energy storage unit, can detect and respond to energy storage unit faults in the first instance; the PCS unit, as the power conversion unit, can quickly respond to various anomalies on both the grid and power sides. This collaborative control mode based on functional division of labor achieves both precise fault source location and rapid fault isolation through coordinated action at both ends, significantly improving the operational safety and reliability of the energy storage system.

[0036] In the description of this invention, it should be noted that the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A DC-side control architecture for an energy storage system, characterized in that, Includes energy storage units, PCS units, and BCU units; A positive main switch device and a pre-charge switch unit are provided in parallel between the positive terminal of the energy storage unit and the positive terminal of the PCS unit. The pre-charge switch unit includes a pre-charge switch device and a pre-charge resistor connected in series. A negative main switch device is provided between the negative terminal of the energy storage unit and the negative terminal of the PCS unit. The PCS control unit of the PCS unit is configured to control the on / off state of the positive main switch device and the precharge switch device, so as to realize the orderly connection between precharge and main power transmission. The BCU control unit of the BCU unit is configured to control the on / off state of the negative main switching device.

2. The DC-side control architecture of the energy storage system according to claim 1, characterized in that, The first terminal of the positive main switch device and the first terminal of the precharge switch unit are connected to the same terminal of the positive terminal of the energy storage unit; The second terminal of the positive main switch device and the second terminal of the precharge switch unit are connected to the same terminal on the positive end of the PCS unit.

3. The DC-side control architecture of the energy storage system according to claim 1, characterized in that, It also includes a PMU power management unit, which is communicatively connected to the BCU control unit and the PCS control unit respectively. It is configured to receive energy storage unit status information reported by the BCU control unit and grid-side status information reported by the PCS control unit, issue global coordination instructions to the BCU control unit and the PCS control unit, and synchronously trigger the disconnection action of the positive and negative main switching devices under fault conditions.

4. The DC-side control architecture of the energy storage system according to claim 1, characterized in that, The BCU control unit and the PCS control unit are communicatively connected. The two control units are configured to independently trigger the disconnection protection action of the corresponding side switching device based on their own monitoring status when a fault condition is detected.

5. A DC-side control method for an energy storage system, applicable to the DC-side control architecture of the energy storage system according to any one of claims 1-4, characterized in that, Includes the following steps: S1. In response to the system startup command, the BCU unit and the PCS unit perform power-on self-test in parallel; S2. If both the BCU unit and the PCS unit pass the self-test, then proceed to step S3. S3. The BCU control unit controls the negative main switch device to close and detects the closing status of the negative main switch device; S4. If the negative main switch device is successfully closed, the BCU control unit sends the closing status information of the negative main switch device to the PCS control unit and executes step S5. S5. In response to receiving the closing status information of the negative main switch device, the PCS control unit controls the pre-charge switch device to close and monitors the DC bus voltage; S6. If the DC bus voltage reaches a preset threshold within a preset time, the PCS control unit controls the positive main switch device to close and executes step S7. S7. The PCS control unit detects the closed state of the positive main switch device; S8. If the positive main switch device closes successfully, after confirming that the positive main switch device is stably conducting, control the precharge switch device to open and complete the system startup.

6. The DC-side control method for an energy storage system according to claim 5, characterized in that, Step S4 further includes: if the negative main switch fails to close, the BCU control unit reports the fault to the PMU power management unit and terminates the process.

7. The DC-side control method for an energy storage system according to claim 5, characterized in that, Step S6 further includes: if the DC bus voltage does not reach the preset threshold within a preset time, the PCS control unit reports to the PMU power management unit and terminates the process.

8. The DC-side control method for an energy storage system according to claim 5, characterized in that, Step S8 further includes: if the positive main switch device fails to close, the PCS control unit reports the fault to the PMU power management unit and terminates the process.

9. The DC-side control method for an energy storage system according to claim 5, characterized in that, Also includes: During operation, when the BCU control unit detects a fault on the energy storage unit side, it controls the disconnection of the negative main switch device and reports the information to the PMU power management unit. The fault information is simultaneously sent to the PCS control unit, triggering the positive main switch device on the PCS unit side to disconnect, thereby achieving rapid isolation at both ends.

10. The DC-side control method for an energy storage system according to claim 5, characterized in that, Also includes: During operation, when the PCS control unit detects a grid-side fault or receives a shutdown command, it controls the disconnection of the positive main switch device and reports the information to the PMU power management unit.

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