Energy storage converter cabinet with double DC / DC converters and control method

Abstract

The invention discloses an energy storage converter cabinet with double DC / DC converters. The energy storage converter cabinet comprises a cabinet body, a bidirectional DC / AC converter, a first DC / DC converter, a second DC / DC converter, a common DC bus and a central controller, the AC side of the bidirectional DC / AC converter is connected with a local AC load and / or a power grid, and the DC side is connected with a common DC bus; the low-voltage end of the first DC / DC converter is connected with the battery pack, and the high-voltage end is connected with the common DC The first end of the second DC / DC converter is connected with the photovoltaic array, and the second end is connected with the common DC bus; the central controller is connected with the bidirectional DC / AC converter, the first DC / DC converter and the second DC / DC converter; according to the power grid instruction, the battery state and the photovoltaic power generation condition, the bidirectional DC / AC converter, the first DC / DC converter and the second DC / DC converter are controlled, and photovoltaic power, battery power and power grid power are dispatched in real time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy, in particular to a dual DC / DC converter energy storage converter cabinet and a control method. BACKGROUND

[0002] With the increasing penetration of new energy power generation represented by photovoltaic, energy storage systems have become the key equipment for smoothing power fluctuations, achieving energy time shift and improving grid stability. Energy storage converter (PCS) is the core of the energy storage system, responsible for controlling the charging and discharging of the battery.

[0003] However, the existing conventional PCS cabinet has the following technical bottlenecks: Low system integration, high cost: The traditional "photovoltaic inverter + PCS + battery" system solution has many devices, and an independent photovoltaic inverter is needed to convert DC to AC, and then the PCS converts AC back to DC to charge the battery. In this process, there are two energy conversions (DC-AC-DC), resulting in reduced system efficiency and significant energy loss. At the same time, multiple independent devices increase the floor area, initial investment and maintenance cost.

[0004] Rigid topology, insufficient flexibility: Most PCSs use a single DC / AC bidirectional converter to connect to the battery and the grid. When connecting to photovoltaic and other distributed DC power sources, an additional DC / DC converter or micro-inverter is required, and the system topology is not expandable, and cannot achieve flexible and efficient coupling on the DC side.

[0005] Extensive energy management, poor economy: In the traditional solution, photovoltaic power generation needs to be connected to the grid or supplied to local AC loads first, and only the excess energy is charged to the battery through the PCS. This approach cannot achieve the most direct and efficient charging of the battery by photovoltaic power generation, especially in off-grid or weak grid environments, the economy and reliability of system operation are restricted.

[0006] Dynamic response and multi-source coordinated control are complex: In the face of grid load fluctuations and intermittent photovoltaic power, the system composed of multiple independent devices has slow coordinated control response, complex algorithm, and it is difficult to achieve millisecond-level precise distribution and smooth switching of power.

[0007] Therefore, there is an urgent need in the art for a highly integrated, efficient and flexible PCS solution to solve the above problems. SUMMARY

[0008] The present application provides a novel dual DC / DC converter energy storage converter cabinet and a control method to solve the problems and deficiencies of the prior art.

[0009] The present application solves the above technical problems by the following technical solutions: The application provides a dual DC / DC converter energy storage converter cabinet, comprising a cabinet body and a bidirectional DC / AC converter, a first DC / DC converter, a second DC / DC converter, a common DC bus and a central controller arranged in the cabinet body. The bidirectional DC / AC converter has an AC side and a DC side, the AC side is used for connecting a local AC load and / or a power grid, and the DC side is connected to the common DC bus. The first DC / DC converter is a bidirectional buck-boost converter, having a low-voltage end and a high-voltage end, the low-voltage end is connected to a battery pack, and the high-voltage end is connected to the common DC bus; when the battery pack is discharging, the voltage of the battery pack is boosted to the voltage of the common DC bus; when the battery pack is charging, the voltage of the common DC bus is bucked to a voltage suitable for charging the battery pack. The second DC / DC converter has a first end and a second end; the first end is connected to a photovoltaic array to extract the generated power of the photovoltaic array; and the second end is connected to the common DC bus to stably boost or buck the photovoltaic DC voltage with a large variation range to the voltage of the common DC bus. The common DC bus serves as a common DC connection point and an energy exchange hub of the bidirectional DC / AC converter, the first DC / DC converter and the second DC / DC converter. The central controller is connected to the bidirectional DC / AC converter, the first DC / DC converter and the second DC / DC converter respectively; according to the grid instruction, the battery state and the photovoltaic power generation condition, the central controller controls the bidirectional DC / AC converter, the first DC / DC converter and the second DC / DC converter to work, and schedules the flow direction and size of the photovoltaic power, the battery power and the grid power in real time.

[0010] Preferably, the second DC / DC converter is a unidirectional or bidirectional MPPT buck-boost converter, which extracts the maximum generated power of the photovoltaic array in real time through a maximum power point tracking algorithm.

[0011] Preferably, a photovoltaic interface is arranged on the cabinet body, and the first end of the second DC / DC converter is connected to the photovoltaic interface to connect the photovoltaic array through the photovoltaic interface.

[0012] Preferably, the central controller is connected to the bidirectional DC / AC converter, the first DC / DC converter and the second DC / DC converter through an RS485 bus or a CAN bus to obtain state information or issue control commands.

[0013] Preferably, the central controller is connected to the photovoltaic array to obtain the power generation state of the photovoltaic array, and the central controller is connected to the battery pack to obtain the remaining power of the battery pack.

[0014] Preferably, the AC side of the bidirectional DC / AC converter is connected to a meter, which measures the amount of electricity flowing through it. The central controller communicates with the meter via an RS485 bus or a CAN bus to obtain the electricity information.

[0015] Based on the same concept, the present invention also provides a control method for the above-mentioned dual DC / DC converter energy storage converter cabinet, comprising the following steps: S1: The central controller acquires the power generation status of the photovoltaic array and controls the bidirectional DC / AC converter, the first DC / DC converter, and the second DC / DC converter according to the power generation status of the photovoltaic array. S2: If the photovoltaic array is in full power generation state and the power generation is greater than the local AC load, the power generation of the photovoltaic array is boosted by the second DC / DC converter and converted to AC by the bidirectional DC / AC converter to supply power to the local AC load. The excess power is boosted by the second DC / DC converter and de-energized by the first DC / DC converter to charge the battery pack. S3: If the photovoltaic array is in a state of insufficient power generation, and the power generation is less than the local AC load, the power generation of the photovoltaic array is boosted by the second DC / DC converter and converted to AC by the bidirectional DC / AC converter to supply power to the local AC load; when the battery pack has no backup power requirement, the insufficient part of the local AC load is supplied by the battery pack after being boosted by the first DC / DC converter and converted to AC by the bidirectional DC / AC converter; when the battery pack has a backup power requirement, the insufficient part of the local AC load is supplied by the grid. S4: If the photovoltaic array is not generating electricity, the photovoltaic array operates at low power or is in standby mode; during the off-peak period of the power grid, the battery pack is charged by the power grid through the bidirectional DC / AC converter for AC-DC conversion and the first DC / DC converter for step-down; during the peak period of the power grid, the battery pack supplies power to the local AC load through the first DC / DC converter for step-up and the bidirectional DC / AC converter for DC-AC conversion.

[0016] Preferably, step S2 further includes: the excess power supplied by the photovoltaic array to the local AC load is used to charge the battery pack until the remaining power of the battery pack is greater than or equal to a set full-charge threshold, at which point the battery pack is considered fully charged, and the first DC / DC converter is controlled to stop charging the battery pack; if the grid allows access, the excess power supplied by the photovoltaic array to the local AC load is boosted by the second DC / DC converter and converted to AC by the bidirectional DC / AC converter and then fed back to the grid; if the grid does not allow access, the power generation of the photovoltaic array and / or the output power of the second DC / DC converter are controlled so that the power generation is less than or equal to the local AC load.

[0017] Preferably, step S2 further includes: the photovoltaic array supplying excess power to the local AC load to charge the battery pack until the remaining power of the battery pack is less than a set full charge threshold, and the photovoltaic array has no excess power to continue charging the battery pack; if the power grid allows power to be drawn, the power from the power grid is converted from AC to DC by a bidirectional DC / AC converter and stepped down by a first DC / DC converter to continue charging the battery pack until the remaining power of the battery pack is greater than or equal to the set full charge threshold, at which point charging of the battery pack stops; if the power grid does not allow power to be drawn, the first DC / DC converter is controlled to stop charging the battery pack, and the battery pack remains in its current standby state.

[0018] Preferably, step S3 further includes: when the battery pack has no backup power requirement and the local AC load is insufficient, the battery pack supplies power to the local AC load. If the remaining power of the battery pack is less than or equal to the set discharge threshold, the battery pack stops discharging, and the local AC load is insufficient and supplied by the grid.

[0019] The positive and progressive effects of this invention are as follows: The dual DC / DC converter energy storage converter cabinet and control method provided by this invention directly integrate the photovoltaic interface and MPPT function into the cabinet, eliminating the need for a separate photovoltaic inverter, reducing external wiring and equipment quantity; lowering initial system cost, installation cost, and floor space; forming a "photovoltaic array → second DC / DC converter → common DC bus → first DC / DC converter →" configuration. The optimal DC charging path for the battery pack reduces one DC-AC and one AC-DC conversion stage, significantly reducing energy loss and improving overall system efficiency. It features flexible operation modes and intelligent control; the photovoltaic array can directly and efficiently charge the battery pack without an inverter, making it particularly suitable for storing low-cost photovoltaic energy during off-peak electricity periods. Flexible power allocation allows the central controller to flexibly allocate power across three ports, enabling the photovoltaic array to simultaneously charge the battery pack and supply power to the load. The grid and photovoltaic array can jointly charge the battery pack and jointly supply power to the grid. Enhanced dynamic response and grid support capabilities are achieved because both the photovoltaic array and battery pack are connected to the common DC bus via fast-response DC / DC converters. The central controller can precisely control their power output at the millisecond level, enabling faster and smoother responses to grid frequency regulation and peak shaving needs, thus enhancing grid friendliness. Improved system reliability and maintainability are further enhanced by integrating all core components into a standardized cabinet, reducing external connection failure points and facilitating centralized monitoring, diagnosis, and maintenance. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a dual DC / DC converter energy storage converter cabinet according to an embodiment of the present invention; Figure 2This is a flowchart of the control method for a dual DC / DC converter energy storage converter cabinet according to an embodiment of the present invention; Figure 3 This is an application illustration of the dual DC / DC converter energy storage converter cabinet according to an embodiment of the present invention. Figure 1 ; Figure 4 This is an application illustration of the dual DC / DC converter energy storage converter cabinet according to an embodiment of the present invention. Figure 2 .

[0021] In the picture: 1-Cabinet; 11-Photovoltaic interface; 2-Bidirectional DC / AC converter; 3-First DC / DC converter; 4-Second DC / DC converter; 5-Common DC bus; 6-Central controller; 7-Photovoltaic array; 8-Battery pack; 9-Meter. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. 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.

[0023] Please see Figure 1 This embodiment provides a dual DC / DC converter energy storage converter cabinet, including a cabinet 1 and a bidirectional DC / AC converter 2, a first DC / DC converter 3, a second DC / DC converter 4, a common DC bus 5 and a central controller 6 disposed in the cabinet 1.

[0024] The bidirectional DC / AC converter 2 has an AC side and a DC side. The AC side is used to connect to the local AC load and / or the power grid, and the DC side is connected to the common DC bus 5.

[0025] The first DC / DC converter 3 is a bidirectional buck-boost converter with a low-voltage side and a high-voltage side. The low-voltage side is connected to the battery pack 8, and the high-voltage side is connected to the common DC bus 5. When the battery pack 8 is discharging, the voltage of the battery pack 8 is boosted to the voltage of the common DC bus. When the battery pack 8 is charging, the voltage of the common DC bus is stepped down to a voltage suitable for charging the battery pack 8.

[0026] The second DC / DC converter 4 has a first terminal and a second terminal; the first terminal is connected to the photovoltaic array 7 to extract the power generated by the photovoltaic array 7; the second terminal is connected to the common DC bus 5 to stabilize and step up / down the photovoltaic DC voltage, which has a large variation range, to the common DC bus voltage.

[0027] The common DC bus 5 serves as the common DC connection point and energy exchange hub for the bidirectional DC / AC converter 2, the first DC / DC converter 3, and the second DC / DC converter 4.

[0028] The central controller 6 is connected to the bidirectional DC / AC converter 2, the first DC / DC converter 3, and the second DC / DC converter 4 respectively. According to the grid command, battery status, and photovoltaic power generation, it controls the operation of the bidirectional DC / AC converter 2, the first DC / DC converter 3, and the second DC / DC converter 4, and schedules the flow and magnitude of photovoltaic power, battery power, and grid power in real time.

[0029] In some embodiments, the second DC / DC converter 4 is a unidirectional or bidirectional MPPT (Maximum Power Point Tracking) buck-boost converter, and the second DC / DC converter 4 extracts the maximum power generation of the photovoltaic array 7 in real time through the maximum power point tracking algorithm.

[0030] In some embodiments, a photovoltaic interface 11 is provided on the cabinet 1, and the first end of the second DC / DC converter 4 is connected to the photovoltaic interface 11, and the photovoltaic array 7 is connected through the photovoltaic interface 11.

[0031] In some embodiments, the central controller 6 is connected to the bidirectional DC / AC converter 2, the first DC / DC converter 3, and the second DC / DC converter 4 via an RS485 bus or a CAN bus to obtain status information or issue control commands.

[0032] In some embodiments, the central controller 6 is connected to the photovoltaic array 7 to obtain the power generation status of the photovoltaic array 7; the central controller 6 is connected to the battery pack 8 to obtain the remaining power of the battery pack 8.

[0033] In some embodiments, a meter 9 is connected to the AC side of the bidirectional DC / AC converter 2. The meter 9 measures the amount of electricity flowing through it. The central controller 6 communicates with the meter 9 via an RS485 bus or a CAN bus to obtain the electricity information, which includes voltage, current and power.

[0034] Please see Figure 2 This embodiment also provides a control method for a dual DC / DC converter energy storage converter cabinet, including the following steps: S1: The central controller 6 obtains the power generation status of the photovoltaic array 7, and controls the bidirectional DC / AC converter 2, the first DC / DC converter 3 and the second DC / DC converter 4 according to the power generation status of the photovoltaic array 7.

[0035] S2: If the photovoltaic array 7 is in full power generation (strong sunlight), the power generation is greater than the local AC load. The power generation of the photovoltaic array 7 is boosted by the second DC / DC converter 4 and converted from DC to AC by the bidirectional DC / AC converter 2 to supply power to the local AC load. The excess power is boosted by the second DC / DC converter 4 and stepped down by the first DC / DC converter 3 to charge the battery pack 8.

[0036] S3: If the photovoltaic array 7 is in a state of insufficient power generation (poor sunlight), and the power generation is less than the local AC load, the power generation of the photovoltaic array 7 is boosted by the second DC / DC converter 4 and converted to AC by the bidirectional DC / AC converter 2 to supply power to the local AC load; when the battery pack 8 has no backup power requirement, the part of the local AC load that is insufficient is supplied by the battery pack 8 through the first DC / DC converter 3 and converted to AC by the bidirectional DC / AC converter 2; when the battery pack 8 has a backup power requirement, the part of the local AC load that is insufficient is supplied by the grid.

[0037] S4: If the photovoltaic array 7 is not generating electricity (weak sunlight), the photovoltaic array 7 will operate at low power or standby. During the off-peak period of the power grid, the battery pack 8 will be charged by the power grid through the bidirectional DC / AC converter 2 for AC-DC conversion and the first DC / DC converter 3 for step-down. During the peak period of the power grid, the battery pack 8 will supply power to the local AC load through the first DC / DC converter 3 for step-up and the bidirectional DC / AC converter 2 for DC-AC conversion.

[0038] In some embodiments, step S2 further includes: the excess power supplied by the photovoltaic array 7 to the local AC load is used to charge the battery pack 8 until the remaining power of the battery pack 8 is greater than or equal to a set full charge threshold, at which point the battery pack 8 is considered fully charged, and the first DC / DC converter 3 is controlled to stop charging the battery pack 8; if the grid allows access, the excess power supplied by the photovoltaic array 7 to the local AC load is boosted by the second DC / DC converter 4 and converted from DC to AC by the bidirectional DC / AC converter 2 and fed back to the grid; if the grid does not allow access, the power generation of the photovoltaic array 7 and / or the output power of the second DC / DC converter 4 are controlled so that the power generation is less than or equal to the local AC load.

[0039] In some embodiments, step S2 further includes: the excess power supplied by the photovoltaic array 7 to the local AC load is used to charge the battery pack 8 until the remaining power of the battery pack 8 is less than a set full charge threshold, and the photovoltaic array 7 has no excess power to continue charging the battery pack 8; if the power grid allows power to be drawn, the power from the power grid is converted from AC to DC by the bidirectional DC / AC converter 2 and stepped down by the first DC / DC converter 3 to continue charging the battery pack 8 until the remaining power of the battery pack 8 is greater than or equal to the set full charge threshold, and then charging the battery pack 8 stops; if the power grid does not allow power to be drawn, the first DC / DC converter 3 is controlled to stop charging the battery pack 8, and the battery pack 8 remains in the current standby state.

[0040] In some embodiments, step S3 further includes: when the battery pack 8 has no backup power requirement and the local AC load is insufficient, the battery pack 8 supplies power to the local AC load. If the remaining power of the battery pack 8 is less than or equal to the set discharge threshold, the battery pack 8 stops discharging, and the local AC load is insufficient and supplied by the grid.

[0041] Please see Figure 3 After the grid connection transformer is connected to the AC side of the bidirectional DC / AC converter 2, the grid and photovoltaic array 7 are connected to the grid. The transformer converts the voltage on the AC side of the bidirectional DC / AC converter 2 into a voltage that matches the grid.

[0042] Please see Figure 4 After the STS (Static Transfer Switch) device is connected to the grid, it is connected to the AC side of the bidirectional DC / AC converter 2. When the STS device is connected, the grid and the photovoltaic array 7 are connected to the grid. When the STS device is disconnected, the grid and the photovoltaic array 7 are disconnected from the grid, forming a microgrid supported by the photovoltaic array and the battery pack 8, which has high reliability.

[0043] In summary, the dual DC / DC converter energy storage inverter cabinet and control method provided by this invention directly integrates the photovoltaic interface 11 and MPPT function into the cabinet 1, eliminating the need for a separate photovoltaic inverter and reducing the number of external wiring and equipment; reducing initial system costs, installation costs, and floor space; forming an optimal DC charging path of "photovoltaic array 7 → second DC / DC converter 4 → common DC bus 5 → first DC / DC converter 3 → battery pack 8", reducing one DC-AC and one AC-DC conversion stage, significantly reducing energy loss and improving overall system efficiency; flexible operation mode and intelligent control, the photovoltaic array 7 can directly and efficiently charge the battery pack 8 without going through the inverter stage, making it particularly suitable for storing low-priced electricity during off-peak hours. Photovoltaic power; flexible power distribution: the central controller 6 can flexibly allocate power to the three ports; the photovoltaic array 7 can simultaneously charge the battery pack 8 and supply power to the load; the grid and the photovoltaic array 7 can jointly charge the battery pack 8; the battery pack 8 and the photovoltaic array 7 can jointly supply power to the grid; improved dynamic response and grid support capabilities: since both the photovoltaic array 7 and the battery pack 8 are connected to the common DC bus 5 through a fast-response DC / DC converter, the central controller 6 can perform millisecond-level precise control of their power output, thereby responding to the grid's frequency regulation and peak shaving needs more quickly and smoothly, enhancing grid friendliness; enhanced system reliability and maintainability: all core components are integrated into a standardized cabinet, reducing external connection failure points and facilitating centralized monitoring, diagnosis, and maintenance.

[0044] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A dual DC / DC converter energy storage converter cabinet, characterized in that, It includes a cabinet and a bidirectional DC / AC converter, a first DC / DC converter, a second DC / DC converter, a common DC bus, and a central controller, all housed within the cabinet. The bidirectional DC / AC converter has an AC side and a DC side. The AC side is used to connect to the local AC load and / or the power grid, and the DC side is connected to the common DC bus. The first DC / DC converter is a bidirectional buck-boost converter with a low-voltage side and a high-voltage side. The low-voltage side is connected to the battery pack, and the high-voltage side is connected to the common DC bus. When the battery pack is discharging, the battery pack voltage is boosted to the common DC bus voltage. When the battery pack is charging, the common DC bus voltage is stepped down to a voltage suitable for charging the battery pack. The second DC / DC converter has a first terminal and a second terminal; the first terminal is connected to the photovoltaic array to extract the power generated by the photovoltaic array; the second terminal is connected to the common DC bus to stabilize and step up / down the photovoltaic DC voltage, which has a large variation range, to the voltage of the common DC bus. The common DC bus serves as the common DC connection point and energy exchange hub for the bidirectional DC / AC converter, the first DC / DC converter, and the second DC / DC converter. The central controller is connected to the bidirectional DC / AC converter, the first DC / DC converter, and the second DC / DC converter respectively. Based on grid commands, battery status, and photovoltaic power generation, it controls the operation of the bidirectional DC / AC converter, the first DC / DC converter, and the second DC / DC converter, and schedules the flow and magnitude of photovoltaic power, battery power, and grid power in real time.

2. The dual DC / DC converter energy storage converter cabinet as described in claim 1, characterized in that, The second DC / DC converter is a unidirectional or bidirectional MPPT buck-boost converter. The second DC / DC converter extracts the maximum power output of the photovoltaic array in real time through the maximum power point tracking algorithm.

3. The dual DC / DC converter energy storage converter cabinet as described in claim 1, characterized in that, The cabinet is equipped with a photovoltaic interface, and the first end of the second DC / DC converter is connected to the photovoltaic interface, and the photovoltaic array is connected through the photovoltaic interface.

4. The dual DC / DC converter energy storage converter cabinet as described in claim 1, characterized in that, The central controller is connected to the bidirectional DC / AC converter, the first DC / DC converter, and the second DC / DC converter via an RS485 bus or a CAN bus to obtain status information or issue control commands.

5. The dual DC / DC converter energy storage converter cabinet as described in claim 1, characterized in that, The central controller is connected to the photovoltaic array to obtain the power generation status of the photovoltaic array; the central controller is connected to the battery pack to obtain the remaining power of the battery pack.

6. The dual DC / DC converter energy storage converter cabinet as described in claim 1, characterized in that, The AC side of the bidirectional DC / AC converter is connected to a meter that measures the amount of electricity flowing through it. The central controller communicates with the meter via an RS485 bus or a CAN bus to obtain the electricity information.

7. A control method for a dual DC / DC converter energy storage converter cabinet as described in any one of claims 1-6, characterized in that, Includes the following steps: S1: The central controller acquires the power generation status of the photovoltaic array and controls the bidirectional DC / AC converter, the first DC / DC converter, and the second DC / DC converter according to the power generation status of the photovoltaic array. S2: If the photovoltaic array is in full power generation state and the power generation is greater than the local AC load, the power generation of the photovoltaic array is boosted by the second DC / DC converter and converted to AC by the bidirectional DC / AC converter to supply power to the local AC load. The excess power is boosted by the second DC / DC converter and de-energized by the first DC / DC converter to charge the battery pack. S3: If the photovoltaic array is in a state of insufficient power generation, and the power generation is less than the local AC load, the power generation of the photovoltaic array is boosted by the second DC / DC converter and converted to AC by the bidirectional DC / AC converter to supply power to the local AC load; when the battery pack has no backup power requirement, the insufficient part of the local AC load is supplied by the battery pack after being boosted by the first DC / DC converter and converted to AC by the bidirectional DC / AC converter; when the battery pack has a backup power requirement, the insufficient part of the local AC load is supplied by the grid. S4: If the photovoltaic array is not generating electricity, the photovoltaic array operates at low power or is in standby mode; during the off-peak period of the power grid, the battery pack is charged by the power grid through the bidirectional DC / AC converter for AC-DC conversion and the first DC / DC converter for step-down; during the peak period of the power grid, the battery pack supplies power to the local AC load through the first DC / DC converter for step-up and the bidirectional DC / AC converter for DC-AC conversion.

8. The control method for a dual DC / DC converter energy storage converter cabinet as described in claim 7, characterized in that, Step S2 further includes: the excess power supplied by the photovoltaic array to the local AC load is used to charge the battery pack until the remaining power of the battery pack is greater than or equal to the set full charge threshold, at which point the battery pack is considered fully charged and the first DC / DC converter is controlled to stop charging the battery pack; if the grid allows access, the excess power supplied by the photovoltaic array to the local AC load is boosted by the second DC / DC converter and converted to AC by the bidirectional DC / AC converter and then fed back to the grid; if the grid does not allow access, the power generation of the photovoltaic array and / or the output power of the second DC / DC converter are controlled so that the power generation is less than or equal to the local AC load.

9. The control method for a dual DC / DC converter energy storage converter cabinet as described in claim 7, characterized in that, Step S2 further includes: the photovoltaic array supplies excess power to the local AC load to charge the battery pack until the remaining power of the battery pack is less than the set full charge threshold, and the photovoltaic array has no excess power to continue charging the battery pack; if the power grid allows power to be drawn, the power from the power grid is converted from AC to DC by the bidirectional DC / AC converter and stepped down by the first DC / DC converter to continue charging the battery pack until the remaining power of the battery pack is greater than or equal to the set full charge threshold, and then charging the battery pack stops; if the power grid does not allow power to be drawn, the first DC / DC converter is controlled to stop charging the battery pack, and the battery pack remains in the current standby state.

10. The control method for a dual DC / DC converter energy storage converter cabinet as described in claim 7, characterized in that, Step S3 further includes: when the battery pack has no backup power requirement and the local AC load is insufficient, the battery pack supplies power to the local AC load. If the remaining power of the battery pack is less than or equal to the set discharge threshold, the battery pack stops discharging, and the local AC load is insufficient and supplied by the grid.

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