Charging and discharging power adjusting method and direct current converter system

Abstract

The invention relates to a charging and discharging power adjusting method and a direct-current converter system, a power battery in the system is connected with a power grid through a direct-current converter and a converter, the direct-current converter and the converter are connected through a direct-current bus, a connection point between the converter and the power grid is a grid-connected point, and an alternating-current load is connected with the grid-connected point. Determining the charging and discharging states of the direct-current converter, and comparing the sum of the charging power of the direct-current converter and the working power of the alternating-current load with the input power limit value of the grid-connected point according to the charging and discharging states of the direct-current converter; or comparing the difference between the discharge power of the direct-current converter and the working power of the alternating-current load with the output power limit value of the grid-connected point, and adjusting and controlling the output power reference values of the direct-current converter and the converter according to the comparison result. The charging and discharging efficiency of the power battery can be improved, and the influence on the stability of a power grid in the charging and discharging process of the power battery can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of power regulation and control, and in particular to a charging and discharging power regulation method in an AC / DC charging process and a DC converter system. Background Art

[0002] With the popularity of electric vehicles, the issue of charging has attracted more and more attention. DC charging piles can directly provide high-power DC power to electric vehicle batteries, greatly shortening the charging time. This is especially important for long-distance travel and emergency situations that require rapid power replenishment. At present, the development of charging pile technology is in a period of rapid change. DC fast charging technology is gradually replacing traditional AC slow charging technology and entering thousands of households due to its advantages in fast charging. However, the DC charging piles configured for home use have higher requirements for the home power distribution system, resulting in the following technical problems: (1) In order to meet the high-power charging needs of DC charging piles, the current capacity of the household power distribution system must be increased; (2) When the grid capacity is weak, high-power charging may cause the voltage at the grid connection point to drop, causing undervoltage shutdown and affecting charging continuity; (3) Changes in AC load will cause charging power instability, resulting in reduced charging efficiency for electric vehicles.

[0003] These problems together limit the efficient use of DC charging piles and affect the charging experience of electric vehicle users, making how to achieve efficient, fast and real-time charging of charging piles an urgent problem that needs to be solved in this field. Summary of the invention

[0004] A main purpose of the present invention is to overcome at least one of the above-mentioned defects, and to provide a charging and discharging power regulation method and a DC converter system, which can not only improve the charging and discharging efficiency of the power battery, but also reduce the impact of the power battery charging and discharging process on the stability of the power grid.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: The present invention provides a charging and discharging power regulation method, wherein a power battery is connected to a power grid via a DC converter and a current transformer, wherein the DC converter and the current transformer are connected via a DC bus, wherein the connection point between the current transformer and the power grid is a grid connection point, and an AC load is connected to the grid connection point, wherein the charging and discharging state of the DC converter is determined, When the DC converter is in a charging state, the sum of the charging power of the DC converter and the working power of the AC load is compared with the grid-connected point input power limit value, and the output power reference value of the converter and the DC converter is adjusted and controlled according to the comparison result; When the DC converter is in a discharging state, the difference between the discharge power of the DC converter and the working power of the AC load is compared with the grid-connected point output power limit value, and the output power reference values ​​of the DC converter and the converter are adjusted and controlled according to the comparison result.

[0006] According to one embodiment of the present invention, when the DC converter is in a charging state, If the sum of the charging power of the DC converter and the working power of the AC load is greater than the grid-connected point input power limit value, the difference between the grid-connected point input power limit value and the grid-connected point real-time power is controlled as the input of the regulator to calculate and determine the output power reference value of the converter, and the difference between the DC converter bus voltage reference value and the real-time voltage of the DC bus is controlled as the input of the regulator to calculate and determine the output power reference value of the DC converter.

[0007] According to one embodiment of the present invention, when the DC converter is in a charging state, If the sum of the charging power of the DC converter and the working power of the AC load is less than the input power limit value of the grid connection point, the difference between the converter bus voltage reference value and the real-time voltage of the DC bus is controlled as the input of the regulator to calculate and determine the output power reference value of the converter, and the DC converter is controlled to use the DC converter charging power limit value as the output power reference value of the DC converter to adjust the operation of the DC converter.

[0008] According to one of the embodiments of the present invention, when the DC converter is in a charging state, the converter bus voltage reference value is greater than the DC converter bus voltage reference value.

[0009] According to one embodiment of the present invention, when the DC converter is in a discharging state, If the difference between the discharge power of the DC converter and the working power of the AC load is greater than the output power limit value of the grid-connected point, the difference between the output power limit value of the grid-connected point and the real-time power of the grid-connected point is controlled as the input of the regulator to calculate and determine the output power reference value of the converter, and the difference between the bus voltage reference value of the DC converter and the real-time voltage of the DC bus is controlled as the input of the regulator to calculate and determine the output power reference value of the DC converter.

[0010] According to one embodiment of the present invention, when the DC converter is in a discharging state, If the difference between the discharge power of the DC converter and the operating power of the AC load is less than the output power limit value of the grid connection point, the control calculates the reference value of the output power of the converter with the difference between the reference value of the converter bus voltage and the real-time voltage of the DC bus as the input of the regulator, and the DC converter adjusts its operation with the discharge power limit value of the DC converter as the output power of the DC converter.

[0011] According to one embodiment of the present invention, when the DC converter is in the discharge state, the reference value of the converter bus voltage is less than the reference value of the DC converter bus voltage.

[0012] In particular, the present invention provides a DC converter system, in which the system executes the charge and discharge power regulation method as described above to regulate the charge and discharge power between the power battery and the power grid.

[0013] According to one embodiment of the present invention, the DC converter system includes a DC converter, a converter, a controller, and a power acquisition device. The power battery is connected to the power grid through the DC converter and the converter. The DC converter and the converter are connected by a DC bus. The connection point between the converter and the power grid is the grid connection point, and the AC load is connected to the grid connection point. The input end of the power acquisition device is connected to the grid connection point, and the output end of the power acquisition device is connected to the input end of the controller. The controller is connected to both the DC converter and the converter. The controller adjusts and controls the reference values of the output powers of the DC converter and the converter according to the charge and discharge state of the DC converter and the input and output powers of the grid connection point.

[0014] According to one embodiment of the present invention, the controller includes a converter control unit and a DC converter control unit. The converter control unit is connected to the converter, and the DC converter control unit is connected to the DC converter. According to one embodiment of the present invention, the converter control unit includes a converter power upper limit control module, a converter power lower limit control module, and a converter bus voltage control module. The converter power upper limit control module uses the difference between the grid connection point output power limit value and the grid connection point real-time power as the input of the regulator, and obtains the output of the converter power upper limit control module after passing through the regulator; the converter power lower limit control module uses the difference between the grid connection point input power limit value and the grid connection point real-time power as the input of the regulator, and obtains the output of the converter power lower limit control module after passing through the regulator; the converter bus voltage control module uses the difference between the converter bus voltage reference value and the DC bus real-time voltage as the input of the regulator, and obtains the output of the converter bus voltage control module after passing through the regulator, and the output of the converter bus voltage control module is processed by limiting to generate an output power reference value for adjusting and controlling the converter.

[0015] According to one embodiment of the present invention, the DC converter control unit includes a DC converter bus voltage control module, which uses the difference between the DC converter bus voltage reference value and the DC bus real-time voltage as the input of the regulator, and obtains the output of the DC converter bus voltage control module after passing through the regulator. The output of the DC converter bus voltage control module is processed by limiting to generate an output power reference value for adjusting and controlling the DC converter.

[0016] Compared with the prior art, the advantages and beneficial effects of the charging and discharging power regulation method and the DC converter system of the patent application of the present invention are: The charging and discharging power regulation method of the present application monitors the grid connection point power and DC bus voltage in real time, combines the charging and discharging status of the DC converter connected to the power battery, and uses a closed-loop control system to dynamically adjust the charging and discharging power of the DC converter. It can overcome the impact of high-power charging on the stability of the power grid and the energy scheduling delay, low charging efficiency and power control fluctuation caused by the master-slave communication delay, and can ensure the working stability of the DC converter system while improving the DC charging and discharging efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings: Figure 1 is a flow chart of a charging and discharging power regulation method according to an embodiment of the present invention; Figure 2 is a structural schematic diagram of a DC converter system according to an embodiment of the present invention; Figure 3is a schematic diagram of a module structure of a converter control unit according to an embodiment of the present invention; Figure 4 is a schematic diagram of a module structure of a DC converter control unit according to an embodiment of the present invention; Figure 5 is a schematic diagram of energy flow relationship in a charging scenario according to a charging and discharging power adjustment method according to an embodiment of the present invention; Figure 6 Schematic diagram of energy flow relationship in a discharge scenario according to a charge and discharge power regulation method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0020] Embodiment 1: This embodiment describes a charging and discharging power regulation method for a DC converter system. The structure of the DC converter system is as follows: Figure 2 As shown, the power battery is connected to the power grid via a DC converter and a converter. The DC converter and the converter are connected via a DC bus. The connection point between the converter and the power grid is a grid connection point. The AC load is connected to the grid connection point. The working process of the method is as follows Figure 1 As shown, wherein the charge and discharge state of the DC converter is determined, When the DC converter is in a charging state, the sum of the charging power of the DC converter and the working power of the AC load is compared with the grid-connected point input power limit value, and the output power reference value of the converter and the DC converter is adjusted and controlled according to the comparison result; When the DC converter is in a discharging state, the difference between the discharge power of the DC converter and the working power of the AC load is compared with the grid-connected point output power limit value, and the output power reference values ​​of the DC converter and the converter are adjusted and controlled according to the comparison result.

[0021] The method described in this embodiment is to monitor the grid connection point power and DC bus voltage in real time, combined with the charging and discharging status of the DC converter connected to the power battery, and use a closed-loop control system to dynamically adjust the charging and discharging power of the DC converter. It can overcome the impact of high-power charging on the stability of the power grid and the energy scheduling delay, low charging efficiency and power control fluctuation caused by the master-slave communication delay, and can ensure the working stability of the DC converter system while improving the DC charging and discharging efficiency.

[0022] Next, depending on whether the DC converter is in a charging state or a discharging state, the sum or difference of the working power of the DC converter and the working power of the AC load is compared with the input or output power limit value of the grid connection point, and the working mode and power of the converter and the DC converter are determined based on the comparison result.

[0023] In one embodiment, when the DC converter is in a charging state, the converter bus voltage reference value is greater than the DC converter bus voltage reference value, and the control logic at this time is as follows: If the sum of the charging power of the DC converter and the working power of the AC load is greater than the grid-connected point input power limit value, the difference between the grid-connected point input power limit value and the grid-connected point real-time power is used as the input of the regulator to calculate and determine the output power reference value of the converter, and the difference between the DC converter bus voltage reference value and the real-time voltage of the DC bus is used as the input of the regulator to calculate and determine the output power reference value of the DC converter; If the sum of the charging power of the DC converter and the working power of the AC load is less than the input power limit value of the grid connection point, the difference between the converter bus voltage reference value and the real-time voltage of the DC bus is used as the input of the regulator to calculate and determine the output power reference value of the converter, and the DC converter is controlled to use the DC converter charging power limit value as the output power reference value of the DC converter to adjust the operation of the DC converter; If the sum of the charging power of the DC converter and the working power of the AC load is equal to the grid-connected point input power limit value, no regulation will be performed.

[0024] In one embodiment, when the DC converter is in a discharging state, the converter bus voltage reference value is less than the DC converter bus voltage reference value, and the control logic at this time is as follows: If the difference between the discharge power of the DC converter and the working power of the AC load is greater than the output power limit value of the grid connection point, the difference between the output power limit value of the grid connection point and the real-time power of the grid connection point is used as the input of the regulator to calculate and determine the output power reference value of the converter, and the difference between the bus voltage reference value of the DC converter and the real-time voltage of the DC bus is used as the input of the regulator to calculate and determine the output power reference value of the DC converter; If the difference between the discharge power of the DC converter and the working power of the AC load is less than the output power limit value of the grid-connected point, the difference between the converter bus voltage reference value and the real-time voltage of the DC bus is used as the input of the regulator to calculate and determine the output power reference value of the converter, and the DC converter uses the DC converter discharge power limit value as the output power of the DC converter to adjust the operation of the DC converter; If the difference between the discharge power of the DC converter and the working power of the AC load is equal to the grid-connected point output power limit value, no regulation will be performed.

[0025] The above converter bus voltage reference value and DC converter bus voltage reference value The DC bus voltage request value is related to the state of the DC converter. The expression is: in is the DC bus voltage request value, and To make the converter bus voltage reference value and the DC converter bus voltage reference value meet the DC bus voltage request value. and are greater than 0. When the DC converter is in charging state, > ; When the DC converter is in the discharge state, < . That is, corresponding to the foregoing, when the DC converter is in a charging state, the converter bus voltage reference value is greater than the DC converter bus voltage reference value; when the DC converter is in a discharging state, the converter bus voltage reference value is less than the DC converter bus voltage reference value.

[0026] As for the DC bus voltage request value Request value from converter DC bus and DC converter bus request value The larger value of is determined by . The expression is: Among them, the converter DC bus request value Determined by the rated voltage on the grid side, its expression is: in is the rated voltage on the grid side, The adjustment amount required to enable the converter to work normally is generally a constant greater than 0.

[0027] DC converter bus request value It is determined by the voltage of the power battery, and its expression is: in is the voltage of the power battery, It can be positive or negative. Generally, for a step-down DC converter, is a positive value; for a boost DC converter, is a negative value; for a step-up and step-down DC converter, when the DC converter works in the step-up mode, is a negative value. When working in step-down mode, Is a positive value.

[0028] In the above two implementations, the output power is calculated by using a regulator, and the regulator used may be a common PI regulator, PD regulator, adaptive regulator, etc., which controls the input of the regulator to calculate the corresponding power value.

[0029] The input and output power of the converter has upper and lower limits, where the upper limit of the converter power is based on the output power limit value of the grid connection point. Real-time power of the grid-connected point The difference is used as the input of the regulator, and the upper limit of the converter power is obtained after passing through the regulator. , the grid-connected point output power limit value The maximum power limit fed to the grid; the lower power limit of the converter is the input power limit value of the grid connection point. Real-time power of the grid-connected point The difference is used as the input of the regulator, and the lower limit of the converter power is obtained after passing through the regulator. , the grid-connected point input power limit value The maximum power limit absorbed from the grid. Control is based on the converter bus voltage reference value Real-time DC bus voltage The difference is used as the regulator input to calculate and determine the output power reference value of the converter When the power limit is calculated, the upper and lower limits of the converter power are used for limiting processing to serve as the final converter output power reference value. .

[0030] The DC converter bus voltage reference value Real-time DC bus voltage The difference is used as the input of the regulator, and the output power of the DC converter is obtained after passing through the regulator. , the output power of this DC converter Also passed the DC converter power limit , DC converter power lower limit After the limiting process, the output power value for adjusting and controlling the DC converter is generated Among them, the upper limit of DC converter power The maximum charging power limit of the DC converter, that is, the maximum power limit fed to the power battery; the lower power limit of the DC converter It is the maximum discharge power limit of the DC converter, that is, the maximum power limit value absorbed from the power battery.

[0031] The upper limit of the DC converter power is the minimum value among the rated charging power of the DC converter, the operating derating power of the DC converter (such as temperature derating, etc.) and the power battery charging request power. The power battery charging request power refers to the maximum power that the battery can accept when charging. This value is determined through communication between the electric vehicle and the DC converter; the lower limit of the DC converter power is the minimum value among the rated discharge power of the DC converter, the operating derating power of the DC converter (such as temperature derating, etc.) and the power battery discharge request power. The power battery discharge request power refers to the maximum power that the power battery can accept when discharging. This value is determined through communication between the equipment to which the power battery belongs and the DC converter.

[0032] Embodiment 2: This embodiment describes a DC converter system, such as Figure 2 As shown, the DC converter system includes a DC converter, a converter, a controller, and a power collection device. The power battery is connected to the power grid via the DC converter and the converter. The DC converter and the converter are connected via a DC bus. The connection point between the converter and the power grid is a grid connection point. The AC load is connected to the grid connection point. The input end of the power collection device is connected to the grid connection point. The output end of the power collection device is connected to the input end of the controller. The controller is connected to the DC converter and the converter. The controller adjusts and controls the output power reference value of the DC converter and the converter according to the charging and discharging state of the DC converter and the input and output power of the grid connection point.

[0033] The DC converter system of this embodiment executes the charging and discharging power regulation method as described in Embodiment 1, which is used to regulate the charging and discharging power between the power battery and the power grid.

[0034] In one embodiment, the controller includes a converter control unit and a DC converter control unit, wherein the converter control unit is connected to the converter, and the DC converter control unit is connected to the DC converter. Specifically, if Figure 3As shown, the converter control unit includes a converter power upper limit control module, a converter power lower limit control module, and a converter bus voltage control module. The converter power upper limit control module outputs a power limit value at the grid connection point. Real-time power of the grid-connected point The difference is used as the input of the regulator, and the output of the converter power upper limit control module is obtained after passing through the regulator; the converter power lower limit control module uses the grid-connected point input power limit value Real-time power of the grid-connected point The difference is used as the input of the regulator, and the output of the converter power lower limit control module is obtained after passing through the regulator; the converter bus voltage control module uses the converter bus voltage reference value Real-time DC bus voltage The difference is used as the regulator input, and the output of the converter bus voltage control module is obtained after passing through the regulator. , the output of the converter bus voltage control module After the limiting process, the output power reference value for adjusting and controlling the converter is generated .

[0035] like Figure 4 As shown, the DC converter control unit includes a DC converter bus voltage control module, which uses the DC converter bus voltage reference value Real-time DC bus voltage The difference is used as the input of the regulator, and the output of the DC converter bus voltage control module is obtained after passing through the regulator. , the output of the DC converter bus voltage control module After the limiting process, the output power reference value for adjusting and controlling the DC converter is generated .

[0036] The charging and discharging power regulation method and DC converter system of the present application monitor the grid connection point power and DC bus voltage in real time and use a closed-loop control system to dynamically adjust the charging and discharging power of the DC converter. The specific implementation steps are as follows: (1) Data acquisition: real-time data collection of grid-connected point power and DC bus voltage, and input of the collected power and voltage data into the controller; (2) Controller adjustment: The controller dynamically adjusts the controller state according to the charging and discharging power of the DC converter, the AC load power, and the input and output power limits of the grid connection point to determine the output power reference value of the converter and DC converter; (3) Power control: The calculated output power reference values of the converter and the DC converter are respectively input into the power control modules in the converter and the DC converter. Each power control module generates a PWM waveform to precisely control the output powers of the converter and the DC converter.

[0037] Working example 1: Charging scenario In the charging scenario, energy flows from the DC bus through the DC converter into the power battery, and at this time the power battery is in the charging state. The energy of the DC bus comes from the power grid, and the power grid energy flows into the DC bus through the converter. The energy flow direction at this time is as Figure 5 shown.

[0038] When the sum of the charging power of the DC converter and the AC load power is greater than the grid connection point input power limit, the controller is in state one. It controls to calculate the output power reference value of the converter by taking the difference between the grid connection point input power limit value and the real-time power of the grid connection point as the input of the regulator, and controls to calculate the output power reference value of the DC converter by taking the difference between the DC converter bus voltage reference value and the real-time voltage of the DC bus as the input of the regulator. That is to say, the power reference value of the converter is controlled by the converter power lower limit control module, and the power reference value of the DC converter is controlled by the bus voltage control module of the DC converter. At this time, the middle DC bus voltage is controlled by the DC converter.

[0039] When the sum of the charging power of the DC converter and the AC load power is less than the grid connection point input power limit, the controller is in state two. It controls to calculate the output power reference value of the converter by taking the difference between the converter bus voltage reference value and the real-time voltage of the DC bus as the input of the regulator, and controls the DC converter to adjust its operation with the DC converter charging power limit value as the output power reference value of the DC converter. That is to say, the power reference value of the converter is controlled by the converter bus voltage control module, and the power reference value of the DC bus is controlled by the power upper limit control module of the DC converter. At this time, the middle DC bus voltage is controlled by the converter.

[0040] Working example 2: Discharging scenario In the discharging scenario, energy flows from the power battery through the DC converter into the DC bus, and at this time the power battery is in the discharging state. The energy on the DC bus can be output to the power grid through the converter or supply power to the AC load. The energy flow direction at this time is as Figure 6 shown.

[0041] When the difference between the discharge power of the DC converter and the AC load power is greater than the grid-connected point output power limit, the controller is in state three, and the difference between the grid-connected point output power limit and the grid-connected point real-time power is used as the input of the regulator to calculate and determine the output power reference value of the converter, and the difference between the DC converter bus voltage reference value and the real-time voltage of the DC bus is used as the input of the regulator to calculate and determine the output power reference value of the DC converter. In other words, the converter power upper limit control module controls the converter power reference value, and the DC converter bus voltage control module controls the DC converter power reference value. At this time, the DC bus voltage in the middle is controlled by the DC converter.

[0042] When the difference between the discharge power of the DC converter and the AC load power is less than the output power limit of the grid connection point, the controller is in state four, and the difference between the converter bus voltage reference value and the real-time voltage of the DC bus is used as the input of the regulator to calculate and determine the output power reference value of the converter, and the DC converter uses the DC converter discharge power limit value as the output power of the DC converter to adjust the operation of the DC converter. In other words, the converter bus voltage control module controls the power reference value of the converter, and the power lower limit control module of the DC converter controls the power reference value of the DC bus. At this time, the DC bus voltage in the middle is controlled by the converter.

[0043] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the contents of the present invention and implement them accordingly. They cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A charging and discharging power regulation method, wherein a power battery is connected to a power grid via a DC converter and a converter, wherein the DC converter and the converter are connected via a DC bus, wherein the connection point between the converter and the power grid is a grid connection point, and an AC load is connected to the grid connection point, wherein: determining a charge and discharge state of the DC converter, When the DC converter is in a charging state, the sum of the charging power of the DC converter and the working power of the AC load is compared with the grid-connected point input power limit value, and the output power reference value of the converter and the DC converter is adjusted and controlled according to the comparison result; When the DC converter is in a discharging state, the difference between the discharge power of the DC converter and the working power of the AC load is compared with the grid-connected point output power limit value, and the output power reference values ​​of the DC converter and the converter are adjusted and controlled according to the comparison result.

2. The charge and discharge power regulation method according to claim 1, characterized in that: When the DC converter is in a charging state, If the sum of the charging power of the DC converter and the working power of the AC load is greater than the grid-connected point input power limit value, the difference between the grid-connected point input power limit value and the grid-connected point real-time power is controlled as the input of the regulator to calculate and determine the output power reference value of the converter, and the difference between the DC converter bus voltage reference value and the real-time voltage of the DC bus is controlled as the input of the regulator to calculate and determine the output power reference value of the DC converter.

3. The charging and discharging power regulation method according to claim 1, characterized in that: When the DC converter is in a charging state, If the sum of the charging power of the DC converter and the working power of the AC load is less than the input power limit value of the grid connection point, the difference between the converter bus voltage reference value and the real-time voltage of the DC bus is controlled as the input of the regulator to calculate and determine the output power reference value of the converter, and the DC converter is controlled to use the DC converter charging power limit value as the output power reference value of the DC converter to adjust the operation of the DC converter.

4. The charging and discharging power regulation method according to claim 3, characterized in that: When the DC converter is in a charging state, the converter bus voltage reference value is greater than the DC converter bus voltage reference value.

5. The charging and discharging power regulation method according to claim 1, characterized in that: When the DC converter is in a discharging state, If the difference between the discharge power of the DC converter and the working power of the AC load is greater than the output power limit value of the grid-connected point, the difference between the output power limit value of the grid-connected point and the real-time power of the grid-connected point is controlled as the input of the regulator to calculate and determine the output power reference value of the converter, and the difference between the bus voltage reference value of the DC converter and the real-time voltage of the DC bus is controlled as the input of the regulator to calculate and determine the output power reference value of the DC converter.

6. The charging and discharging power regulation method according to claim 1, characterized in that: When the DC converter is in a discharging state, If the difference between the discharge power of the DC converter and the working power of the AC load is less than the output power limit value of the grid-connected point, the difference between the converter bus voltage reference value and the real-time voltage of the DC bus is used as the input calculation of the regulator to determine the output power reference value of the converter, and the DC converter uses the discharge power limit value of the DC converter as the output power of the DC converter to adjust the operation of the DC converter.

7. The charging and discharging power regulation method according to claim 1, characterized in that: When the DC converter is in a discharging state, the converter bus voltage reference value is less than the DC converter bus voltage reference value.

8. A DC converter system, characterized in that: The system executes the charge and discharge power regulation method as described in any one of claims 1 to 7, which is used to regulate the charge and discharge power between the power battery and the power grid.

9. The DC converter system according to claim 8, characterized in that: The DC converter system includes a DC converter, a converter, a controller, and a power collection device. The power battery is connected to the power grid via the DC converter and the converter. The DC converter and the converter are connected via a DC bus. The connection point between the converter and the power grid is a grid connection point. The AC load is connected to the grid connection point. The input end of the power collection device is connected to the grid connection point. The output end of the power collection device is connected to the input end of the controller. The controller is connected to the DC converter and the converter. The controller adjusts and controls the output power reference value of the DC converter and the converter according to the charging and discharging state of the DC converter and the input and output power of the grid connection point.

10. The DC converter system according to claim 9, characterized in that: The controller comprises a converter control unit and a DC converter control unit. The converter control unit is connected to the converter, and the DC converter control unit is connected to the DC converter.

11. The DC converter system according to claim 10, characterized in that: The converter control unit includes a converter power upper limit control module, a converter power lower limit control module, and a converter bus voltage control module. The converter power upper limit control module uses the difference between the grid-connected point output power limit value and the grid-connected point real-time power as the input of the regulator, and obtains the output of the converter power upper limit control module through the regulator; the converter power lower limit control module uses the difference between the grid-connected point input power limit value and the grid-connected point real-time power as the input of the regulator, and obtains the output of the converter power lower limit control module through the regulator; the converter bus voltage control module uses the difference between the converter bus voltage reference value and the DC bus real-time voltage as the input of the regulator, and obtains the output of the converter bus voltage control module through the regulator. The output of the converter bus voltage control module is processed by limiting to generate an output power reference value for adjusting and controlling the converter.

12. The DC converter system according to claim 10, characterized in that: The DC converter control unit includes a DC converter bus voltage control module. The DC converter bus voltage control module uses the difference between the DC converter bus voltage reference value and the DC bus real-time voltage as the input of the regulator, and obtains the output of the DC converter bus voltage control module after passing through the regulator. The output of the DC converter bus voltage control module is processed by limiting to generate an output power reference value for adjusting and controlling the DC converter.

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