Power conversion switching device and control method for photovoltaic and energy storage fusion flexible energy supply system

Abstract

The present invention provides a power conversion and switching device for a photovoltaic-storage fusion flexible energy supply system, including a DC switching circuit having a first DC input end that can be connected and disconnected to the output end of an energy storage battery, and an AC switching circuit having a first AC input end that can be connected and disconnected to the third interface of a photovoltaic-storage inverter. When the difference between the voltage of the energy storage battery and the voltage of the DC load is within a preset range, the first DC input end of the DC switching circuit is connected to the output end of the energy storage battery; when the output power generated by the photovoltaic-storage inverter meets the power demand of the AC load, the third interface of the photovoltaic-storage inverter is connected to the first AC input end of the AC switching circuit. This application improves the stability of the photovoltaic power generation system in dealing with environmental factors such as changes in lighting conditions by configuring the DC switching circuit and the AC switching circuit differently under different load demands, while being compatible with the application of conventional AC systems and new DC systems.

Description

Technical Field

[0001] The present invention relates to the field of power conversion control, and in particular to a power conversion switching device and a control method for a photovoltaic-storage fusion flexible energy supply system. Background Art

[0002] Photovoltaic power generation systems are affected by environmental factors such as light, and show characteristics such as intermittency, volatility and instability. In order to improve its stability, existing technologies usually achieve this by adding energy storage systems. Over time, photovoltaic fusion systems that combine photovoltaics with energy storage have become an important form of photovoltaic power generation applications and a future trend, especially with the development of new technologies such as "photovoltaic storage, direct current and flexible" in recent years. Photovoltaic storage, direct current and flexible refers to a new type of energy system, which is characterized by the integration of photovoltaic power generation, energy storage, DC power distribution and flexible interactive control to achieve efficient utilization and flexible application of energy. However, the power conversion control in existing photovoltaic storage system applications is often only suitable for a single conventional AC system or dedicated DC application, and lacks a comprehensive solution that is compatible with both conventional AC systems and new DC applications. Summary of the invention

[0003] In view of this, the present invention aims to provide a power conversion switching device and control method for a photovoltaic-storage fusion flexible energy supply system to meet the stability requirements of the photovoltaic power generation system when dealing with environmental factors such as changes in lighting conditions, and to solve the technical problem that the existing technology is incompatible with traditional AC loads and DC load applications of the new "photovoltaic-storage-direct-flexible" system.

[0004] In a first aspect, the present invention provides a power conversion switching device for a photovoltaic storage fusion flexible energy supply system, wherein the photovoltaic storage fusion flexible energy supply system comprises a photovoltaic power generation panel, an energy storage battery and a photovoltaic storage inverter, wherein the photovoltaic storage inverter comprises a first interface, a second interface and a third interface, wherein the second interface of the photovoltaic storage inverter is connected to the energy storage battery, and the first interface of the photovoltaic storage inverter is connected to the photovoltaic power generation panel, and the power conversion switching device comprises:

[0005] A DC switching circuit, comprising a first DC input terminal that can be connected to and disconnected from the output terminal of the energy storage battery, wherein the DC switching circuit is configured to connect the first DC input terminal of the DC switching circuit to the output terminal of the energy storage battery when the difference between the voltage of the energy storage battery and the voltage of the DC load is within a preset range;

[0006] An AC switching circuit includes a first AC input terminal that can be connected and disconnected to the third interface of the photovoltaic storage inverter. The AC switching circuit is configured to connect the third interface with the first AC input terminal of the AC switching circuit when the output power generated by the photovoltaic storage inverter meets the power demand of the AC load.

[0007] Optionally, the photovoltaic storage inverter includes a unidirectional DC / DC conversion circuit, a bidirectional DC / DC conversion circuit and a DC bus, the unidirectional DC / DC conversion circuit includes a fourth interface and the first interface of the photovoltaic storage inverter, the bidirectional DC / DC conversion circuit includes a fifth interface and the second interface of the photovoltaic storage inverter, the fourth interface and the fifth interface are both connected to the DC bus, and the DC switching circuit also includes:

[0008] The second DC input terminal is connected to the DC bus in an on-off manner, and the second DC input terminal is configured to be connected to the DC bus when the voltage difference between the energy storage battery and the voltage of the DC load is not within a preset range.

[0009] Optionally, the photovoltaic storage inverter further includes a single-phase DC / AC bridge inverter circuit, and the single-phase DC / AC bridge inverter circuit includes a sixth interface, a first bridge arm, a second bridge arm, a third bridge arm, a fourth bridge arm and the third interface of the photovoltaic storage inverter;

[0010] The DC switching circuit also includes a third DC input terminal, and the third DC input terminal is connectable and disconnectable to the third interface of the photovoltaic storage inverter;

[0011] When the DC load fails, the third DC input terminal is connected to the third interface and the first bridge arm or the fourth bridge arm is disconnected.

[0012] Optionally, the AC switching circuit further includes:

[0013] A second AC input terminal is connected to the power grid in an on-off manner, and the second AC input terminal is configured to be connected to the power grid when the third interface of the photovoltaic storage inverter is connected to the power grid;

[0014] The power conversion switching device is configured to issue a warning message when the third interface of the photovoltaic storage inverter is disconnected from the power grid and the output power generated by the photovoltaic storage inverter does not meet the power demand of the AC load.

[0015] Optionally, the power switching device is also configured to connect the DC switching circuit and disconnect the AC switching circuit when only the DC load has a demand, connect the AC switching circuit and disconnect the DC switching circuit when only the AC load has a demand, and connect the DC switching circuit and connect the AC switching circuit simultaneously when both the demand of the DC load and the demand of the AC load exist.

[0016] Optionally, the power switching device further includes:

[0017] A control circuit, wherein the control circuit is connected to the DC switching circuit and the AC switching circuit respectively, and the control circuit is configured to output different control signals to control the DC switching circuit and the AC switching circuit when the types of the DC load and the AC load are different.

[0018] In a second aspect, the present invention provides a control method for a power conversion switching device for a photovoltaic energy storage fusion flexible energy supply system, comprising the following steps:

[0019] Obtain the load demand of the photovoltaic and energy storage fusion flexible energy supply system and determine the load demand;

[0020] When the load demand is a single DC load and the voltage difference between the energy storage battery and the DC load is within a preset range, controlling the first DC input terminal of the DC switching circuit to be connected to the output terminal of the energy storage battery;

[0021] When the load demand is a separate AC load and the output power generated by the photovoltaic storage inverter meets the power demand of the AC load, the third interface of the photovoltaic storage inverter is controlled to be connected to the first AC input terminal of the AC switching circuit.

[0022] Optionally, the power conversion switching device control method further includes the following steps:

[0023] When the load demand is a separate DC load and the voltage difference between the energy storage battery and the DC load is not within a preset range, controlling the second DC input terminal of the DC switching circuit to be connected to the DC bus;

[0024] When the load requirement is a separate DC load and the DC load fails, the third DC input terminal of the DC switching circuit is controlled to be connected to the third interface of the photovoltaic storage inverter and the first bridge arm or the fourth bridge arm is disconnected.

[0025] Optionally, the power conversion switching device control method further includes:

[0026] When the load demand is a separate AC load and the third interface of the photovoltaic storage inverter is connected to the power grid, controlling the second AC input end of the AC switching circuit to be connected to the power grid;

[0027] When the load demand is a separate AC load and the third interface of the photovoltaic storage inverter is disconnected from the power grid and the output power generated by the photovoltaic storage inverter does not meet the power demand of the AC load, the power conversion switching device is controlled to issue a warning message.

[0028] Optionally, the power conversion switching device control method further includes:

[0029] When the load demand is only the DC load, controlling the DC switching circuit to be connected and controlling the AC switching circuit to be disconnected;

[0030] When the load demand is only the AC load, controlling the AC switching circuit to be connected and controlling the DC switching circuit to be disconnected;

[0031] When the load demand is that the DC load and the AC load exist simultaneously, the DC switching circuit and the AC switching circuit are controlled to be connected simultaneously.

[0032] According to the first aspect of the present invention, when the voltage difference between the energy storage battery and the voltage of the DC load is within a preset range, the first DC input terminal of the DC switching circuit is connected to the output terminal of the energy storage battery; when the output power generated by the photovoltaic storage inverter meets the power demand of the AC load, the third interface of the photovoltaic storage inverter is connected to the first AC input terminal of the AC switching circuit. Through the above-mentioned different configurations of the DC switching circuit and the AC switching circuit, the technical solution of the present invention can be compatible with the application of conventional AC systems and new DC systems at the same time, thereby improving the stability of the photovoltaic power generation system in response to environmental factors such as changes in lighting conditions.

[0033] Furthermore, by controlling the DC switching circuit and the AC switching circuit to connect to different ports of the photovoltaic storage fusion flexible energy supply system respectively when the load demands are different, flexible conversion and control between traditional AC loads, DC loads of the new "photovoltaic storage direct and flexible" system, and AC / DC hybrid load applications are achieved, providing convenience and efficiency for the diversified applications of the system.

[0034] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the connection relationship between the photovoltaic and storage fusion flexible energy supply system and the power conversion switching device of the photovoltaic and storage fusion flexible energy supply system of the present invention.

[0036] Figure 2 It is a schematic diagram of the power conversion device 2 of the photovoltaic energy storage fusion flexible energy supply system of the present invention.

[0037] Figure 3 Schematic diagram of the internal connection relationship of the single-phase DC / AC bridge inverter circuit 123 of the present invention.

[0038] Figure 4 The present invention is a flowchart of a control method for a power conversion switching device of a photovoltaic-storage fusion flexible energy supply system according to an embodiment of the present invention.

[0039] Figure 5 The present invention is a flowchart of a control method for a power conversion switching device of a photovoltaic-storage fusion flexible energy supply system according to another embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. It is to be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some structures related to the present application are shown in the accompanying drawings, rather than all structures. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0041] The terms "including" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0042] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0043] Figure 1 A schematic diagram showing the connection relationship between the photovoltaic-storage fusion flexible energy supply system and the power conversion switching device of the photovoltaic-storage fusion flexible energy supply system of the present invention is shown. Figure 2 It is a schematic diagram of the power conversion device 2 of the photovoltaic energy storage fusion flexible energy supply system of the present invention.

[0044] like Figure 1As shown, the photovoltaic-storage fusion flexible energy supply system 1 includes a photovoltaic panel 11, a photovoltaic-storage inverter 12 and an energy storage battery 13. The photovoltaic-storage inverter 12 includes a unidirectional DC / DC conversion circuit 121, a bidirectional DC / DC conversion circuit 122, a single-phase DC / AC bridge inverter circuit 123 and a DC bus. Among them, the interface 1211 of the unidirectional DC / DC conversion circuit 121 is the first interface of the photovoltaic-storage inverter 12, the interface 1221 of the bidirectional DC / DC conversion circuit 122 is the second interface of the photovoltaic-storage inverter 12, and the interface 1231 of the single-phase DC / AC bridge inverter circuit 123 is the third interface of the photovoltaic-storage inverter 12. The power conversion device 2 of the photovoltaic-storage fusion flexible energy supply system includes a control circuit 21, a DC switching circuit 22 and an AC switching circuit 23.

[0045] like Figure 1 As shown in the connection relationship, in the photovoltaic-storage fusion flexible energy supply system 1, the interface 1211 is connected to the photovoltaic panel 11, and the interface 1221 is connected to the energy storage battery. In the photovoltaic-storage fusion flexible energy supply system power conversion switching device 2, the DC switching circuit 22 and the AC switching circuit 23 are both connected to the control circuit 21. In order to provide the load with the required electrical energy, the DC switching circuit 22 is connected to the DC load 3, and the AC switching circuit 23 is connected to the AC load 4. In the DC switching circuit, the first DC input terminal 221 can be connected and disconnected to the output terminal of the energy storage battery 13, the second DC input terminal 222 can be connected and disconnected to the DC bus, and the third DC input terminal 223 can be connected and disconnected to the interface 1231. In the AC switching circuit, the first AC input terminal 231 can be connected and disconnected to the interface 1231, and the second AC input terminal 232 can be connected and disconnected to the power grid.

[0046] like Figure 2 As shown, the control circuit 21 includes a load type input module 211, a control chip module 212, an indication module 213 and a communication module 214. The control chip module 212 is used to receive information from the load type input module, parse and analyze it, output a corresponding switching control instruction, and synchronously update the indication module 213, and perform real-time data communication of the switching control information through the communication module 214.

[0047] In some embodiments, the control chip uses a STC32G8K48 single-chip microcomputer, and the switching circuit is composed of a multi-contact relay.

[0048] In some embodiments, in combination Figure 2 , when the DC load 3 is not faulty and the voltage U BAT_DC The voltage U of the DC load 3 L_DC The difference of |U L_DC -U BAT_DC |In the load allowable range U L_DC_SetWhen the DC load 3 is connected to the first DC input terminal 221, the energy storage battery 13 directly supplies power to the DC load 3 through the first DC input terminal 221, thereby reducing the DC / DC conversion link and thus reducing the energy loss caused by the DC / DC conversion link.

[0049] When the photovoltaic storage inverter 12 is disconnected from the grid and the output power P generated by the photovoltaic storage inverter 12 INV_AC The power P of AC load 4 is satisfied L_AC , the control circuit 21 outputs the relevant switching control instruction to the AC switching circuit 23 through the indication module 213, and controls the first AC input terminal 231 of the AC switching circuit 23 to be connected with the interface 1231. At this time, the energy storage battery 13 converts the internal DC power into AC power through the single-phase DC / AC bridge inverter circuit 123, and supplies power to the AC load 4 through the first AC input terminal 231 connected to the interface 1231.

[0050] According to this implementation, by configuring the DC switching circuit and the AC switching circuit differently when the requirements of the DC load and the AC load are different, the technical solution of the present invention is compatible with both conventional AC systems and new DC applications, thereby improving the stability of the photovoltaic power generation system in response to environmental factors such as changes in lighting conditions.

[0051] In other embodiments, in combination Figure 2 , when the DC load 3 is not faulty and the voltage U BAT_DC The voltage U of the DC load 3 L_DC The difference of |U L_DC -U BAT_DC |Not within the load range allowedU L_DC_Set When the DC voltage in the energy storage battery 13 is increased or decreased through the bidirectional DC / DC conversion circuit 122, the energy storage battery 13 supplies power to the DC load 3 through the second DC input terminal 222.

[0052] Figure 3 FIG. 1 is a schematic diagram showing the internal connection relationship of the single-phase DC / AC bridge inverter circuit 123 of the present invention. Figure 3 As shown, the single-phase DC / AC bridge inverter circuit 123 internally includes a first bridge arm 1232 , a second bridge arm 1233 , a third bridge arm 1234 and a fourth bridge arm 1235 .

[0053] In other embodiments, Figure 1 , Figure 2 and Figure 3 As shown, when the DC load 3 fails, the control circuit 21 outputs the relevant switching control instruction to the DC switching circuit 22 through the indication module 213, and controls the third DC input terminal 223 of the DC switching circuit 22 to be connected with the interface 1231. At this time, the first bridge arm 1232 and the fourth bridge arm 1235 are in a connected state, and the second bridge arm 1233 and the third bridge arm 1234 are in a disconnected state. When the DC load 3 fails, the first bridge arm 1232 or the fourth bridge arm 1235 is disconnected to achieve isolation of the fault of the DC load 3.

[0054] In other embodiments, see Figure 1 and Figure 2 As shown, when the photovoltaic storage inverter 12 is connected to the grid, the control circuit 21 outputs the relevant switching control instruction to the AC switching circuit 23 through the indication module 213, and controls the second AC input terminal 232 of the AC switching circuit 23 to be connected to the grid. At this time, the grid directly supplies power to the AC load 4 through the second AC input terminal 232.

[0055] In other embodiments, see Figure 1 and Figure 2 As shown, when the photovoltaic storage inverter 12 is disconnected from the grid and the output power P generated by the photovoltaic storage inverter 12 is INV_AC The power P of AC load 4 is not satisfied L_AC When required, the control circuit 21 sends an AC output warning message through the communication module 214.

[0056] In other embodiments, see Figure 1 As shown, when the load types are different, the photovoltaic-storage fusion flexible energy supply system 1 and the photovoltaic-storage fusion flexible energy supply system power conversion switching device 2 will have different connection modes. The load types include when there is only a demand for the DC load 3, when there is only a demand for the AC load 4, and when there are demands for both the DC load 3 and the AC load 4.

[0057] When there is only a demand for DC load 3, combined with Figure 2, the control circuit 21 outputs the relevant switching control instructions to the DC switching circuit 22 and the AC switching circuit 23 through the indication module 213, controls the DC switching circuit 22 to be connected, and controls the AC switching circuit 23 to be disconnected; when there is only the demand of the AC load 4, the control circuit 21 outputs the relevant switching control instructions to the DC switching circuit 22 and the AC switching circuit 23 through the indication module 213, controls the AC switching circuit 23 to be connected, and controls the DC switching circuit 22 to be disconnected; when the demand of the DC load 3 and the AC load 4 exist at the same time, the control circuit 21 outputs the relevant switching control instructions to the DC switching circuit 22 and the AC switching circuit 23 through the indication module 213, controls the DC switching circuit 22 and the AC switching circuit 23 to be connected at the same time. The specific connection methods of the DC switching circuit 22 and the AC switching circuit 23 in different situations are the same as those in the above embodiments, and will not be repeated here.

[0058] In other embodiments, when the demands of the DC load 3 and the AC load 4 exist simultaneously and the total power supply power P of the photovoltaic energy storage fusion flexible energy supply system 1 is PV+BAT Cannot meet the total power P of all DC loads 3 L_DC and the total power P of AC load 4 L_AC When the requirement is met, the priority of the DC load and the AC load is set according to the user's priority requirements for the specific load. After sorting them from high to low in priority, the power supply is switched and controlled in the manner of the above embodiment, which will not be described in detail here.

[0059] According to the above embodiment, by controlling the DC switching circuit and the AC switching circuit to be connected to different ports of the photovoltaic storage fusion flexible energy supply system respectively when the load demand type is different, flexible conversion and control between traditional AC loads, DC loads of the new "photovoltaic storage direct and flexible" system, and AC / DC hybrid load applications are achieved, providing convenience and efficiency for the diversified applications of the system.

[0060] Figure 4 The flowchart of the control method of the power conversion switching device of the photovoltaic storage fusion flexible energy supply system according to one embodiment of the present invention is shown. Figure 4 As shown, the control method of the power conversion switching device of the photovoltaic storage fusion flexible energy supply system includes:

[0061] Step S410, obtaining the load demand of the photovoltaic and energy storage fusion flexible energy supply system and determining the load demand.

[0062] Step S420, when the load requirement is a single DC load and the voltage difference between the energy storage battery and the DC load is within a preset range, control the first DC input terminal of the DC switching circuit to be connected to the output terminal of the energy storage battery.

[0063] Step S430, when the load demand is a single AC load and the output power generated by the photovoltaic storage inverter meets the power demand of the AC load, control the third interface of the photovoltaic storage inverter to be connected to the first AC input terminal of the AC switching circuit.

[0064] Figure 5 A flow chart of a control method for a power conversion switching device of a photovoltaic and energy storage fusion flexible energy supply system according to another embodiment of the present invention is shown. The control method for a power conversion switching device of a photovoltaic and energy storage fusion flexible energy supply system also includes:

[0065] S510, when the load demand is a single DC load and the voltage difference between the energy storage battery and the DC load is not within a preset range, control the second DC input terminal of the DC switching circuit to be connected to the DC bus.

[0066] S520, when the load demand is a single DC load and the DC load fails, control the third DC input terminal of the DC switching circuit to be connected to the third interface of the photovoltaic energy storage inverter and disconnect the first bridge arm or the fourth bridge arm.

[0067] S530, when the load demand is a separate AC load and the third interface of the photovoltaic energy storage inverter is connected to the power grid, control the second AC input terminal of the AC switching circuit to be connected to the power grid.

[0068] S540, when the load demand is a separate AC load and the third interface of the photovoltaic storage inverter is disconnected from the power grid and the output power generated by the photovoltaic storage inverter does not meet the power demand of the AC load, control the power conversion switching device to issue a warning message.

[0069] S550, when the load demand is only DC load, control the DC switching circuit to be connected and control the AC switching circuit to be disconnected; when the load demand is only AC load, control the AC switching circuit to be connected and control the DC switching circuit to be disconnected; when the load demand is that DC load and AC load exist at the same time, control the DC switching circuit and the AC switching circuit to be connected at the same time.

[0070] In the control method of the above-mentioned photovoltaic and storage fusion flexible energy supply system power conversion switching device, the specific implementation methods for different load types refer to the relevant contents of the embodiments in the above-mentioned device, and will not be elaborated here.

[0071] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0072] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A power conversion and switching device for a photovoltaic and energy storage fusion flexible energy supply system, characterized in that: The photovoltaic storage fusion flexible energy supply system comprises a photovoltaic power generation panel, an energy storage battery and a photovoltaic storage inverter, wherein the photovoltaic storage inverter comprises a first interface, a second interface and a third interface, wherein the second interface of the photovoltaic storage inverter is connected to the energy storage battery, and the first interface of the photovoltaic storage inverter is connected to the photovoltaic power generation panel, and the power conversion switching device comprises: A DC switching circuit, comprising a first DC input terminal that can be connected to and disconnected from the output terminal of the energy storage battery, wherein the DC switching circuit is configured to connect the first DC input terminal of the DC switching circuit to the output terminal of the energy storage battery when the difference between the voltage of the energy storage battery and the voltage of the DC load is within a preset range; An AC switching circuit, comprising a first AC input terminal that can be connected to and disconnected from the third interface of the photovoltaic storage inverter, wherein the AC switching circuit is configured to connect the third interface to the first AC input terminal of the AC switching circuit when the output power generated by the photovoltaic storage inverter meets the power demand of the AC load; The photovoltaic storage inverter also includes a single-phase DC / AC bridge inverter circuit, and the single-phase DC / AC bridge inverter circuit includes a sixth interface, a first bridge arm, a second bridge arm, a third bridge arm, a fourth bridge arm and the third interface of the photovoltaic storage inverter; The DC switching circuit also includes a third DC input terminal, and the third DC input terminal is connectable and disconnectable to the third interface of the photovoltaic storage inverter; When the DC load fails, the third DC input terminal is connected to the third interface of the photovoltaic storage inverter. At this time, the first bridge arm and the fourth bridge arm are in a connected state, and the second bridge arm and the third bridge arm are in a disconnected state. When the DC load fails, the first bridge arm or the fourth bridge arm is disconnected.

2. The power conversion switching device according to claim 1, characterized in that: The photovoltaic storage inverter further includes a unidirectional DC / DC conversion circuit, a bidirectional DC / DC conversion circuit and a DC bus, wherein the unidirectional DC / DC conversion circuit includes a fourth interface and the first interface of the photovoltaic storage inverter, and the bidirectional DC / DC conversion circuit includes a fifth interface and the second interface of the photovoltaic storage inverter, wherein the fourth interface and the fifth interface are both connected to the DC bus, and the DC switching circuit further includes: The second DC input terminal is connected to the DC bus in an on-off manner, and the second DC input terminal is configured to be connected to the DC bus when the voltage difference between the energy storage battery and the voltage of the DC load is not within a preset range.

3. The power conversion switching device according to any one of claims 1 to 2, characterized in that: The AC switching circuit also includes: A second AC input terminal is connected to the power grid in an on-off manner, and the second AC input terminal is configured to be connected to the power grid when the third interface of the photovoltaic storage inverter is connected to the power grid; The power conversion switching device is configured to issue a warning message when the third interface of the photovoltaic storage inverter is disconnected from the power grid and the output power generated by the photovoltaic storage inverter does not meet the power demand of the AC load.

4. The power conversion switching device according to claim 3, characterized in that: The power conversion switching device is also configured to connect the DC switching circuit and disconnect the AC switching circuit when only the DC load has a demand, connect the AC switching circuit and disconnect the DC switching circuit when only the AC load has a demand, and connect the DC switching circuit and disconnect the DC switching circuit when both the DC load demand and the AC load demand exist simultaneously.

5. The power conversion switching device according to claim 1, characterized in that: The power conversion switching device also includes: A control circuit is connected to the DC switching circuit and the AC switching circuit respectively, and the control circuit is configured to output different control signals to control the DC switching circuit and the AC switching circuit when the requirements of the DC load and the AC load are different.

6. A control method for a power conversion switching device according to any one of claims 1 to 5, characterized in that: The steps include: Obtain the load demand of the photovoltaic and energy storage fusion flexible energy supply system and determine the load demand; When the load demand is a single DC load and the voltage difference between the energy storage battery and the DC load is within a preset range, controlling the first DC input terminal of the DC switching circuit to be connected to the output terminal of the energy storage battery; When the load demand is a separate AC load and the output power generated by the photovoltaic storage inverter meets the power demand of the AC load, the third interface of the photovoltaic storage inverter is controlled to be connected to the first AC input terminal of the AC switching circuit.

7. The power conversion switching device control method according to claim 6, characterized in that: The following steps are also included: When the load demand is a separate DC load and the voltage difference between the energy storage battery and the DC load is not within a preset range, controlling the second DC input terminal of the DC switching circuit to be connected to the DC bus; When the load requirement is a separate DC load and the DC load fails, the third DC input terminal of the DC switching circuit is controlled to be connected to the third interface of the photovoltaic storage inverter and the first bridge arm or the fourth bridge arm is disconnected.

8. The power conversion switching device control method according to claim 6 or 7, characterized in that: The power conversion switching device control method further includes: When the load demand is a separate AC load and the third interface of the photovoltaic storage inverter is connected to the power grid, controlling the second AC input end of the AC switching circuit to be connected to the power grid; When the load demand is a separate AC load and the third interface of the photovoltaic storage inverter is disconnected from the power grid and the output power generated by the photovoltaic storage inverter does not meet the power demand of the AC load, the power conversion switching device is controlled to issue a warning message.

9. The power conversion switching device control method according to claim 8, characterized in that: The power conversion switching device control method further includes: When the load demand is only the DC load, controlling the DC switching circuit to be connected and controlling the AC switching circuit to be disconnected; When the load demand is only the AC load, controlling the AC switching circuit to be connected and controlling the DC switching circuit to be disconnected; When the load demand is that the DC load and the AC load exist simultaneously, the DC switching circuit and the AC switching circuit are controlled to be connected simultaneously.

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