Photovoltaic power supply system and power supply method

Abstract

The invention provides a photovoltaic power supply system and a power supply method. The photovoltaic power supply system is connected with an alternating current bus of a power grid. Comprising a photovoltaic system and a flywheel energy storage system, and the photovoltaic system and the flywheel energy storage system are connected with an alternating current bus through a grid-connected inverter. The photovoltaic system is used for transmitting grid-connected voltage to the alternating current bus through the grid-connected inverter; and the flywheel energy storage system is used for adjusting the grid-connected voltage output by the photovoltaic system, so that the grid-connected voltage is maintained in a preset fluctuation range. According to the embodiment of the invention, when the grid-connected voltage output by the photovoltaic system is unstable, the grid-connected voltage can be adjusted through the flywheel energy storage system, so that the AC bus obtains the stable grid-connected voltage, and the stability and reliability of power supply are ensured. Besides, the flywheel energy storage system is used for adjusting the grid-connected voltage and shares the grid-connected inverter with the photovoltaic system, so that the photovoltaic power supply system can realize power supply only by using one grid-connected inverter, and the cost effectiveness is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply, and in particular to a photovoltaic power supply system and a power supply method. Background Art

[0002] The current power supply system is mainly based on electrochemical energy storage, which is not a sustainable energy source and is prone to environmental impact during use. In addition, the power supply system also includes a photovoltaic system for power supply. The existing photovoltaic system is an extensive system without an energy storage structure. It is an intermittent power generation unit that realizes power supply according to the intensity of solar radiation. It usually realizes power supply when the solar radiation is sufficient during the day. If the solar radiation cannot be implemented at night, the power supply will be intermittent during the day due to the weather. The photovoltaic system's own regulation ability is very weak. Once the system fails, it will cause disturbances to the power grid, resulting in problems such as reverse current in the power grid. In addition, the photovoltaic system receives solar radiation during the day so that the photovoltaic panels generate DC output to the DC bus to realize photovoltaic power supply. However, the actual light will be affected by different climate changes, resulting in random distribution of radiation. At this time, the DC voltage output by the photovoltaic system fluctuates greatly, so that it cannot provide stable power supply to the power grid. Among them, the state encourages the access of new energy and requires the introduction of industry regulations for energy storage. Flywheel new energy storage has attracted attention.

[0003] Based on this, how to achieve reliability and stability of power supply is particularly important. Summary of the invention

[0004] In view of this, an object of the present invention is to provide a photovoltaic power supply system and a power supply method, which are used in conjunction with a flywheel energy storage system to achieve stable power supply.

[0005] In a first aspect, an embodiment of the present invention provides a photovoltaic power supply system, which is connected to the AC bus of a power grid; the photovoltaic power supply system includes a photovoltaic system and a flywheel energy storage system; the photovoltaic system and the flywheel energy storage system are connected to the AC bus through a grid-connected inverter; the photovoltaic system is used to transmit a grid-connected voltage to the AC bus through a grid-connected inverter; the flywheel energy storage system is used to regulate the grid-connected voltage output by the photovoltaic system so that the grid-connected voltage is maintained within a preset fluctuation range.

[0006] In combination with the first aspect, an embodiment of the present invention provides a first possible implementation scheme of the first aspect, wherein the grid-connected inverter is an AC-DC coupled inverter; the AC-DC coupled inverter includes a DC end and an AC end; the AC end of the AC-DC coupled inverter is connected to the AC bus; and the photovoltaic system and the flywheel energy storage system are connected to the DC end of the AC-DC coupled inverter.

[0007] In combination with the first aspect, an embodiment of the present invention provides a second possible implementation of the first aspect, wherein the photovoltaic power supply system includes a DC bus; the DC bus is arranged at the DC end of the AC-DC coupling inverter; the photovoltaic system and the flywheel energy storage system are connected to the DC bus in parallel, and connected to the AC-DC coupling inverter through the DC bus.

[0008] In combination with the first aspect, an embodiment of the present invention provides a third possible implementation of the first aspect, wherein the flywheel energy storage system includes a flywheel and a DC-AC inverter connected to the flywheel; the DC side of the DC-AC inverter is connected to the DC bus; and the flywheel is connected to the AC side of the DC-AC inverter.

[0009] In combination with the first aspect, an embodiment of the present invention provides a fourth possible implementation of the first aspect, wherein the photovoltaic power supply system also includes a battery unit; the battery unit, the photovoltaic system and the flywheel energy storage system are connected in parallel to the DC bus for energy compensation of the flywheel energy storage system and the photovoltaic system.

[0010] In combination with the first aspect, the embodiment of the present invention provides a fifth possible implementation of the first aspect, wherein the battery unit includes a hydrogen fuel cell.

[0011] In combination with the first aspect, an embodiment of the present invention provides a sixth possible implementation of the first aspect, wherein the flywheel energy storage system is used to adjust the grid-connected voltage output by the photovoltaic system, comprising: obtaining a power curve corresponding to the grid-connected voltage, and starting when the power curve falls, so as to perform power compensation on the grid-connected voltage and realize the adjustment processing operation.

[0012] In combination with the first aspect, an embodiment of the present invention provides a seventh possible implementation of the first aspect, wherein the step of starting up when the power curve drops to perform power compensation on the grid-connected voltage includes: monitoring the ripple changes corresponding to the power curve; and starting up when the ripple value is lower than a preset ripple threshold to perform power compensation on the grid-connected voltage.

[0013] In combination with the first aspect, an embodiment of the present invention provides an eighth possible implementation of the first aspect, wherein the flywheel energy storage system includes an energy-type flywheel system.

[0014] In a second aspect, an embodiment of the present invention further provides a power supply method, which is applied to the above-mentioned photovoltaic power supply system, the photovoltaic power supply system is connected to the AC bus of the power grid; the photovoltaic power supply system includes a photovoltaic system and a flywheel energy storage system; the photovoltaic system and the flywheel energy storage system are connected to the AC bus through a grid-connected inverter; the method includes: the photovoltaic system transmits a grid-connected voltage to the AC bus through a grid-connected inverter; the grid-connected voltage output by the photovoltaic system is adjusted and processed by the flywheel energy storage system to maintain the grid-connected voltage within a preset fluctuation range.

[0015] The embodiments of the present invention bring the following beneficial effects:

[0016] The present invention provides a photovoltaic power supply system and power supply method, wherein a flywheel energy storage system and a photovoltaic system are connected to an AC bus through a grid-connected inverter. When the grid-connected voltage output by the photovoltaic system is unstable, the flywheel energy storage system can be used to adjust the grid-connected voltage so that the AC bus obtains a stable grid-connected voltage, thereby ensuring power supply stability and reliability. In addition, the flywheel energy storage system is connected in parallel to the DC bus between the photovoltaic system and the grid-connected inverter, so that the photovoltaic power supply system can achieve power supply using only one grid-connected inverter, thereby ensuring cost-effectiveness.

[0017] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description and the drawings.

[0018] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A schematic diagram of the structure of a photovoltaic power supply system provided by an embodiment of the present invention;

[0021] Figure 2 A schematic diagram of the structure of another photovoltaic power supply system provided by an embodiment of the present invention;

[0022] Figure 3 A schematic diagram of a topological structure of a photovoltaic power supply system provided by an embodiment of the present invention;

[0023] Figure 4 A flow chart of a power supply method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are 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.

[0025] The current power supply system is mainly based on electrochemical energy storage, which is not a sustainable energy source and is likely to have an impact on the environment during use. In addition, the power supply system also includes photovoltaic systems for power supply. The existing photovoltaic system is an extensive system with no energy storage structure and is an intermittent power generation unit. The photovoltaic system's own regulation ability is very weak. Once the system fails, it will cause disturbances to the power grid, resulting in problems such as power flow reversal in the power grid.

[0026] In addition, the photovoltaic system receives sunlight during the day, so that the photovoltaic panels generate DC output to the DC bus to achieve photovoltaic power supply. However, the actual light will be affected by different climate changes, making the radiation randomly distributed. At this time, the DC voltage output by the photovoltaic system fluctuates greatly, so that it cannot provide stable power supply to the grid. Among them, the country encourages the access of new energy and requires the introduction of industry regulations for energy storage. Flywheel new energy storage has attracted attention.

[0027] Based on this, the present invention provides a photovoltaic power supply system and a power supply method, which are used in conjunction with a flywheel energy storage system to achieve power supply stability and reliability.

[0028] To facilitate understanding of this embodiment, a photovoltaic power supply system disclosed in an embodiment of the present invention is first introduced in detail. The photovoltaic power supply system is connected to the AC bus of the power grid. Figure 1 A schematic diagram of the structure of a photovoltaic power supply system provided by an embodiment of the present invention is shown. Figure 1 As shown, the photovoltaic power supply system includes a photovoltaic system 100 and a flywheel energy storage system 200; the photovoltaic system 100 and the flywheel energy storage system 200 are connected to the AC bus through a grid-connected inverter; the photovoltaic system 100 is used to transmit the grid-connected voltage to the AC bus through the grid-connected inverter; the flywheel energy storage system 200 is used to adjust the grid-connected voltage output by the photovoltaic system 100 so that the grid-connected voltage is maintained within a preset fluctuation range.

[0029] In specific implementation, after the grid-connected inverter and the AC bus are connected, the photovoltaic system 100 will receive solar radiation during the day so that the DC generated by its photovoltaic panels is output to the DC bus 300, generating a grid-connected voltage, which is transmitted to the AC bus through the grid-connected inverter. However, solar radiation is unstable due to weather reasons. At this time, the flywheel energy storage system 200 can be involved in the work to adjust the grid-connected voltage output by the photovoltaic system 100 so that the grid-connected voltage is maintained within a preset fluctuation range.

[0030] A photovoltaic power supply system provided by an embodiment of the present invention connects a flywheel energy storage system and a photovoltaic system to an AC bus through a grid-connected inverter. When the grid-connected voltage output by the photovoltaic system is unstable, the flywheel energy storage system can be used to adjust the grid-connected voltage so that the AC bus obtains a stable grid-connected voltage, thereby ensuring power supply stability and reliability.

[0031] For ease of understanding, based on the above embodiments, the present invention also provides another photovoltaic power supply system. Figure 2 A schematic diagram of the structure of another photovoltaic power supply system provided by an embodiment of the present invention is shown, wherein the grid-connected inverter is an AC-DC coupling inverter, the AC-DC coupling inverter includes a DC end and an AC end, the AC end of the AC-DC coupling inverter is connected to the AC bus, and the photovoltaic system 100 and the flywheel energy storage system 200 are connected to the DC end of the AC-DC coupling inverter. Further, the photovoltaic power supply system includes a DC bus 300, which is arranged at the DC end of the AC-DC coupling inverter, and the photovoltaic system 100 and the flywheel energy storage system 200 are connected to the DC bus 300 in parallel, and are connected to the AC-DC coupling inverter through the DC bus 300.

[0032] For ease of understanding, Figure 3 A schematic diagram of a topological structure of a photovoltaic power supply system provided by an embodiment of the present invention is shown. Figure 3 In the embodiment, the flywheel energy storage system 200 is connected to the DC bus 300 instead of the grid-connected inverter. It is connected to the photovoltaic system 100 in a DC parallel manner. When transmitting the grid-connected voltage to the AC bus, a dedicated inverter can be saved, and a grid-connected inverter can be shared with the photovoltaic system 100. The AC-DC coupling inverter has an AC bus on the left, which is connected to electrical equipment, such as the public power grid, wind farms, and electrical equipment in the station and regional loads. The photovoltaic power supply system on the right side of the AC-DC coupling inverter supplies power to the electrical equipment on the left side.

[0033] The photovoltaic power supply system provided in the embodiment of the present invention also includes a battery unit 400, and the battery unit 400, the photovoltaic system 100 and the flywheel energy storage system 200 are connected in parallel to the DC bus 300, which is used to compensate the flywheel energy storage system 200 and the photovoltaic system 100 for energy. The above-mentioned flywheel energy storage system 200 includes a flywheel and a DC-AC inverter connected to the flywheel, the DC side of the DC-AC inverter is connected to the DC bus 300, and the flywheel is connected to the AC side of the DC-AC inverter. Among them, the DC-AC inverter can realize the conversion of DC power to AC power, and can exchange the power of the battery unit 400 and / or the photovoltaic system 100 to obtain high-quality AC power that can meet the voltage and frequency requirements of the load, so that the flywheel can continue to work. Among them, the flywheel energy storage system 200 includes an energy-type flywheel system, and the flywheel provided is a flywheel technology specifically used for energy storage and frequency modulation applications with a capacity of more than 45 degrees of electricity.

[0034] like Figure 3 As shown, the battery unit 400 is incorporated into the bus of the DC bus 300, and the flywheel energy storage system 200 is incorporated into the DC bus 300 connecting the battery unit 400 and the photovoltaic system 100. At this time, the three are arranged in parallel, and the battery unit 400 works together with the flywheel energy storage system 200 by using the same power electronics. Among them, the battery unit 400 can be used as an uninterruptible power supply, such as a long-term power supply for the flywheel energy storage system 200, a power supply for power consumption within the station, and a starting power supply for the flywheel energy storage system 200 and the photovoltaic system 100. The battery unit 400 can realize the function of a long-term standby generator to meet the power consumption within the station and the starting power supply requirements. Furthermore, the battery unit 400 includes a hydrogen fuel cell, that is, the power supply energy of the embodiment of the present invention is all clean energy.

[0035] In specific implementation, based on the topological structure formed by the flywheel energy storage system 200, the photovoltaic system 100 and the battery unit 400, when the flywheel energy storage system 200 in the embodiment of the present invention adjusts the grid-connected voltage output by the photovoltaic system 100, it first obtains the power curve corresponding to the grid-connected voltage on the DC bus 300, and starts when the power curve falls, so as to perform power compensation on the grid-connected voltage and implement the adjustment processing operation. Specifically, the flywheel energy storage system 200 monitors the ripple changes corresponding to the power curve, and starts when the ripple value is lower than the preset ripple threshold, so as to perform power compensation on the grid-connected voltage.

[0036] Specifically, when the AC-DC coupling inverter is connected to the AC bus, the photovoltaic power supply system is in the grid-connected operation mode. When the 1MW photovoltaic system 100 is exposed to sunlight during the day, its photovoltaic panels generate a DC output to the DC bus 300, generating a grid-connected voltage. However, because the actual illumination is affected by different climate changes, the irradiation is randomly distributed, so the output DC voltage fluctuates greatly, and the ripple changes appear jagged. At this time, the flywheel energy storage system 200 is connected in parallel with the DC to track the fluctuation change, and then the startup is performed when the ripple value is lower than the preset ripple threshold, so as to maintain the voltage fluctuation of the DC bus 300 within the allowable range through real-time online dynamic cycle charging and discharging, and then the adjusted grid-connected voltage is output to the AC bus through the above-mentioned grid-connected inverter to provide it to the public power grid. Based on the corresponding topological structure, the flywheel energy storage system 200 can suppress various power mutations caused by the irradiation of the photovoltaic system 100, and as a power buffer device for climate change, it can ensure stable power supply.

[0037] When the photovoltaic power supply system receives a dispatch instruction instructing it to switch to off-grid mode, the grid-connected inverter will disconnect the loop with the AC bus. If the flywheel energy storage system 200 is not used, the grid-connected voltage received by the public power grid will fluctuate greatly. The public power grid will lose a large amount of active power through the power supply network, causing a short-term disturbance at this node. The flywheel energy storage system 200 set up based on the embodiment of the present invention can be used as a UPS power supply. When the photovoltaic power supply system receives a dispatch instruction, the photovoltaic system 100 can be decoupled first to stop it from providing the grid-connected voltage, and then the grid-connected inverter can be cut off. When the photovoltaic system 100 is decoupled, the flywheel energy storage system 200 can be started based on the obtained ripple value when it drops, and the grid-connected voltage is instantaneously compensated. At this time, the public power grid can still receive the grid-connected voltage from the flywheel energy storage system 200, so that the photovoltaic power supply system is decoupled without disturbance, and the public power grid will not experience large drop fluctuations. The photovoltaic power supply system can be decoupled smoothly. The topology of the photovoltaic power supply system can smoothly transition during the off-grid and grid-connected period of the photovoltaic system 100, avoiding impact on the power grid and also avoiding the reverse flow of the public power grid.

[0038] Furthermore, when the photovoltaic system 100 is disconnected due to internal faults, or is disconnected at night, the flywheel energy storage system 200 and the battery unit 400 can be used together to meet the power demand in the station. Specifically, when the photovoltaic power supply system oscillates due to factors such as closing the switch, grid-side fluctuations, and lightning strikes, the flywheel energy storage system 200 can suppress or compensate according to the strategy within seconds to ensure smooth output.

[0039] When the above factors cause the photovoltaic system 100 to be disconnected from the DC bus 300, the photovoltaic power supply system is impacted for an instant. At this time, the flywheel energy storage system 200 can be connected to the AC bus by the grid-connected inverter, participate in the regulation of the power grid, and perform power compensation for the photovoltaic power supply system. At the same time, the battery unit 400 can be used to maintain the power consumption of the electrical equipment in the photovoltaic power supply system, and can also compensate for the grid-connected voltage of the DC bus 300, and participate in the regulation of the power grid. Based on this, the battery unit 400 and the flywheel energy storage system 200 realize a mixed compensation module, and perform a new mode to complete the frequency regulation function. The two can constitute an independent frequency regulation system corresponding to the microgrid at night or when the photovoltaic system 100 fails and is disconnected. The above power supply enables the photovoltaic power supply system to maintain uninterrupted operation for a long time or even for a week, improves economic efficiency, and saves energy storage and frequency regulation resources.

[0040] The embodiment of the present invention can improve the penetration level of the local photovoltaic power supply system and maintain a stable voltage distribution through the corresponding topological structure and the above-mentioned flywheel energy storage system. When the power generation of the photovoltaic system is at its peak, the flywheel energy storage system can also absorb excess power generation and serve as an energy storage device for the photovoltaic power supply system; the flywheel energy storage system provides rotational inertia to complete the frequency modulation and PQ mode of the project itself, and can perform compensation when the power curve corresponding to the monitored grid-connected voltage falls, thereby improving the power supply capacity and system stability of the photovoltaic power supply system and enhancing the permeability of the photovoltaic power supply system; when the photovoltaic system is cut off or when the photovoltaic power supply system switches from the grid-connected mode to the off-grid mode, the flywheel energy storage system and the battery unit can still be used in grid connection, and the flywheel energy storage system can be used as a UPS power supply in the transition when the mode is switched, and the local area network can be frequency modulated and VF / PQ and other functions can be performed to realize continuous power supply services, and can realize the new function of soft and disturbance-free switching, thereby ensuring the quality and stability of the large power grid, which is beneficial to the public power grid.

[0041] Another photovoltaic power supply system provided by an embodiment of the present invention combines a flywheel energy storage system and a battery unit with a photovoltaic system, uses a flywheel energy storage system for inertia support, and can perform energy compensation through battery units. The whole system is different from the zero emission of electrochemical batteries. The physical energy storage is clean and there are no harmful substances that pollute the environment throughout the entire process, achieving the purpose of low-carbon emission reduction in the true sense. In addition, based on the topological structure corresponding to the embodiment of the present invention, a parallel DC bus topological structure is adopted. Compared with the traditional topology, there is no need to equip the flywheel energy storage system with a separate grid-connected inverter, which ensures cost-effectiveness, higher efficiency and more economy. In this topological structure, only the grid-connected inverter corresponding to the photovoltaic system is used to achieve grid connection, which can be used for reactive power compensation of the power grid.

[0042] Further, based on the above system embodiment, the embodiment of the present invention also provides a power supply method, which is applied to the above photovoltaic power supply system, the photovoltaic power supply system is connected to the AC bus of the power grid; the photovoltaic power supply system includes a photovoltaic system and a flywheel energy storage system; the photovoltaic system and the flywheel energy storage system are connected to the AC bus through a grid-connected inverter; Figure 4 A flow chart of a power supply method provided by an embodiment of the present invention is shown. Figure 4 As shown, the method comprises the following steps:

[0043] Step S102, the photovoltaic system transmits a grid-connected voltage to the AC bus through a grid-connected inverter;

[0044] Step S104, regulating the grid-connected voltage output by the photovoltaic system through the flywheel energy storage system so that the grid-connected voltage is maintained within a preset fluctuation range.

[0045] A power supply method provided in an embodiment of the present invention has the same technical features as a photovoltaic power supply system provided in the above embodiment, so it can also solve the same technical problems and achieve the same technical effects.

[0046] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working process of the system described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here. In addition, in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, and it can be the internal connection of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0048] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0049] Finally, it should be noted that the above embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that any person skilled in the art can still modify the technical solutions recorded in the above embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A photovoltaic power supply system, characterized in that: The photovoltaic power supply system is connected to the AC bus of the power grid; The photovoltaic power supply system includes a photovoltaic system and a flywheel energy storage system; The photovoltaic system and the flywheel energy storage system are connected to the AC bus through a grid-connected inverter; The photovoltaic system is used to transmit grid-connected voltage to the AC bus through the grid-connected inverter; The flywheel energy storage system is used to regulate the grid-connected voltage output by the photovoltaic system so as to maintain the grid-connected voltage within a preset fluctuation range.

2. The photovoltaic power supply system according to claim 1, characterized in that: The grid-connected inverter is an AC-DC coupled inverter; The AC-DC coupled inverter includes a DC end and an AC end; The AC end of the AC-DC coupling inverter is connected to the AC bus; The photovoltaic system and the flywheel energy storage system are connected to the DC terminal of the AC-DC coupling inverter.

3. The photovoltaic power supply system according to claim 2, characterized in that: The photovoltaic power supply system includes a DC bus; The DC bus is arranged at the DC end of the AC-DC coupling inverter; The photovoltaic system and the flywheel energy storage system are connected to the DC bus in parallel, and are connected to the AC-DC coupling inverter through the DC bus.

4. The photovoltaic power supply system according to claim 3, characterized in that: The flywheel energy storage system includes a flywheel and a DC-AC inverter connected to the flywheel; The DC side of the DC-AC inverter is connected to the DC bus; The flywheel is connected to the AC side of the DC-AC inverter.

5. The photovoltaic power supply system according to claim 3, characterized in that: The photovoltaic power supply system also includes a battery unit; The battery unit, the photovoltaic system and the flywheel energy storage system are connected in parallel to the DC bus for energy compensation of the flywheel energy storage system and the photovoltaic system.

6. The photovoltaic power supply system according to claim 5, characterized in that: The battery unit includes a hydrogen fuel cell.

7. The photovoltaic power supply system according to claim 1, characterized in that: The flywheel energy storage system is used to adjust the grid-connected voltage output by the photovoltaic system, comprising: A power curve corresponding to the grid-connected voltage is obtained, and startup is performed when the power curve falls, so as to perform power compensation on the grid-connected voltage and realize the regulation processing operation.

8. The photovoltaic power supply system according to claim 7, characterized in that: The step of starting when the power curve falls to perform power compensation on the grid-connected voltage includes: Monitoring ripple changes corresponding to the power curve; When the value of the ripple is lower than a preset ripple threshold, startup is performed to perform power compensation on the grid-connected voltage.

9. The photovoltaic power supply system according to claim 8, characterized in that: The flywheel energy storage system includes an energy-type flywheel system.

10. A power supply method, characterized in that: The power supply method is applied to the photovoltaic power supply system according to any one of claims 1 to 9, wherein the photovoltaic power supply system is connected to the AC bus of the power grid; the photovoltaic power supply system comprises a photovoltaic system and a flywheel energy storage system; the photovoltaic system and the flywheel energy storage system are connected to the AC bus via a grid-connected inverter; The method comprises: The photovoltaic system transmits grid-connected voltage to the AC bus through the grid-connected inverter; The grid-connected voltage output by the photovoltaic system is regulated by a flywheel energy storage system so that the grid-connected voltage is maintained within a preset fluctuation range.

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