Photovoltaic energy storage system and energy management method thereof

Abstract

The application relates to a photovoltaic energy storage system and an energy management method thereof, and the system comprises at least one photovoltaic energy storage unit, at least one pure energy storage unit, an energy management system and a high-voltage power distribution cabinet; a DC / DC converter is introduced into the photovoltaic energy storage unit to convert photovoltaic power generation from direct current to direct current; the photovoltaic energy storage unit is electrically connected with the high-voltage power distribution cabinet to realize bidirectional flow of electric energy; the pure energy storage unit is electrically connected with the high-voltage power distribution cabinet to realize bidirectional flow of electric energy; the high-voltage power distribution cabinet is connected to a power grid; based on a preset charging and discharging mode, the energy management system performs charging and discharging management on the photovoltaic energy storage unit and the pure energy storage unit according to residual electric quantity of the photovoltaic energy storage unit, residual electric quantity of the pure energy storage unit and output power of the DC / DC converter, so as to realize residual energy deviation balance control. The application can realize continuous stability of system capacity and solve the problem of uncoordinated system energy.

Description

Technical Field

[0001] This application relates to the field of photovoltaic energy storage technology, specifically to a photovoltaic energy storage system and its energy management method. Background Technology

[0002] In a related technology, most photovoltaic energy storage power stations adopt Figure 1 The system architecture is shown below. Photovoltaic (PV) end: Photovoltaic panels connect to a photovoltaic converter, which further converts the energy to high voltage via a transformer. Energy storage end: A lithium-ion battery energy storage container connects to an energy storage converter (PCS), which further converts the energy to high voltage via a booster chamber. Both the PV and energy storage ends are connected to a high-voltage distribution cabinet, which is then connected to the power grid. This enables the PV power plant to connect to the grid and the energy storage container to store electrical energy. In this architecture, multiple such links are connected in parallel on both the PV and energy storage ends. This is the mainstream topology for large-scale PV-to-energy storage systems. However, in this scheme, the energy entering the energy storage section requires multiple conversions through the PV converter, two transformers, and one energy storage converter, resulting in very low efficiency. This approach is suitable for applications with small energy storage capacities.

[0003] In another related technology, the architecture of a photovoltaic energy storage system is as follows: Figure 2 As shown, by introducing a DC-DC converter, the electrical energy of the photovoltaic power station is directly converted into energy suitable for lithium battery energy storage containers, which can reduce... Figure 1 The electrical energy in the medium system architecture enters the energy storage unit circulation process, improving the overall efficiency. Figure 2 Medium-scale architecture topologies are widely used in microgrids, but less so in large-scale photovoltaic (PV) power plants. To cope with low or negative electricity prices during PV power generation, PV power plants are increasingly equipped with larger energy storage capacities. When the energy storage capacity approaches the PV power generation capacity, [further details are needed]. Figure 2 The architecture's topology will bring better photovoltaic energy storage efficiency. Lithium batteries face lifespan degradation during use, and the overall capacity of the energy storage station will gradually decrease during actual use. If users need 100% capacity to remain unchanged during operation, it is necessary to add lithium battery energy storage containers to compensate for the capacity loss due to the lifespan degradation of the original containers. Adding energy storage containers without adding photovoltaic panels will create a coordination issue between the added container portion and the energy storage container connected to the photovoltaic panels. Summary of the Invention

[0004] Based on the above description, this application provides a photovoltaic energy storage system and its energy management method, which can achieve continuous and stable system capacity while realizing the consistency of energy coordination in the energy storage system.

[0005] In a first aspect, this application provides a photovoltaic energy storage system, comprising: at least one photovoltaic energy storage unit, at least one pure energy storage unit, an energy management system, and a high-voltage switchgear; wherein a DC-DC converter is introduced in the photovoltaic energy storage unit to convert photovoltaic power generation from DC to DC.

[0006] The photovoltaic energy storage unit is electrically connected to the high-voltage distribution cabinet to achieve bidirectional flow of electrical energy; the pure energy storage unit is electrically connected to the high-voltage distribution cabinet to achieve bidirectional flow of electrical energy; the high-voltage distribution cabinet is connected to the power grid.

[0007] The remaining energy of the photovoltaic energy storage unit, the remaining energy of the pure energy storage unit, and the average remaining power of the power station are acquired in real time to determine the actual remaining energy deviation of the power station. Based on the actual remaining energy deviation of the power station and the preset total reference deviation of the remaining energy of the power station, the average coordinated power of the power station is determined. The energy management system obtains the charging and discharging mode from the dispatch center and performs charging and discharging management on the photovoltaic energy storage unit and the pure energy storage unit based on the output power of all the DC-DC converters, the average coordinated power of the power station, and the preset reference charging and discharging power, so as to determine the charging and discharging power demand of the photovoltaic energy storage unit and the charging and discharging power demand of the pure energy storage unit, so as to achieve the balance control of the remaining energy deviation.

[0008] In one or more embodiments, the photovoltaic energy storage unit includes a photovoltaic cell array, a DC-DC converter, a first energy storage module, a first converter, a first transformer, and a first coordination controller;

[0009] The photovoltaic cell array is used to generate electricity and outputs electrical energy. After being converted by a DC-DC converter, the electrical energy is output to the corresponding first energy storage module and the corresponding first converter, so that the first converter converts the electrical energy into power and outputs it to the first transformer. The first transformer then steps up the voltage and transmits the electrical energy to the high-voltage distribution cabinet. The first energy storage module is used for energy storage or discharge.

[0010] The first coordination controller is connected to the energy management system and is used to control the DC-DC converter, the first energy storage module and the first converter based on the residual energy deviation balance control strategy.

[0011] In one or more embodiments, the pure energy storage unit includes a second energy storage module, a second converter, a second transformer, and a second coordination controller, wherein the second energy storage module and the second converter are connected; one side of the second converter is sequentially connected to the second transformer and the second coordination controller; and the second coordination controller is connected to the high-voltage distribution cabinet.

[0012] The second energy storage module is used for energy storage or discharge; the second coordination controller is used to control the second energy storage module and the second converter based on the residual energy deviation balance control strategy.

[0013] In one or more embodiments, if the charging and discharging mode is a discharge-allowed mode, the discharge demand power of the photovoltaic energy storage unit is determined based on the output power of all the DC-DC converters, the average coordinated power, and the preset reference discharge power, and based on the difference between the remaining energy of the current photovoltaic energy storage unit and the average remaining power of the power station.

[0014] Based on the output power of all the DC-DC converters, the average coordinated power, and the preset reference discharge power, and based on the difference between the remaining energy of the current pure energy storage unit and the average remaining power of the power station, the discharge demand power of the current pure energy storage unit is determined.

[0015] If the charging and discharging mode is the allowed charging mode, then the charging power demand of the photovoltaic energy storage unit is determined based on the output power of all the DC-DC converters, the average coordinated power, and the preset reference charging power, and based on the difference between the average remaining power of the power station and the remaining energy of the current photovoltaic energy storage unit.

[0016] Based on the output power of all the DC-DC converters, the average coordinated power, and the preset reference charging power, and based on the difference between the average remaining power of the power station and the remaining energy of the current pure energy storage unit, the charging power requirement of the current pure energy storage unit is determined.

[0017] In one or more embodiments, the actual power plant residual energy deviation can be determined according to the following calculation formula. :

[0018] ;

[0019] in, This represents the remaining energy of the A-th photovoltaic energy storage unit; This represents the remaining energy of the Bth pure energy storage unit; This represents the average remaining energy of the power station; A = 1...N, where N is the total number of photovoltaic energy storage units; B = 1...M, where M is the total number of pure energy storage units;

[0020] The average coordinated power of the power plant is determined according to the following formula. :

[0021]

[0022] in, =(M+N)× ; This indicates the total reference deviation of the power plant's remaining energy. Indicates the allowable deviation of the power plant's remaining energy; This represents the average coordinated power coefficient of the energy management system.

[0023] In one or more embodiments, it further includes:

[0024] The remaining energy and average remaining energy of the first energy storage module in the current photovoltaic energy storage unit are obtained in real time, and the actual remaining energy deviation of the current photovoltaic energy storage unit is determined.

[0025] The average coordinated power of the photovoltaic energy storage unit is determined based on the actual remaining energy deviation and the first preset average remaining energy reference deviation in the photovoltaic energy storage unit.

[0026] The photovoltaic energy storage unit obtains the charging and discharging mode from the energy management system, and determines the charging and discharging power demand of the first converter in the photovoltaic energy storage unit based on the output power of the DC-DC converter in the photovoltaic energy storage unit, the average coordinated power of the photovoltaic energy storage unit, and the charging and discharging power demand.

[0027] In one or more embodiments, the actual remaining energy deviation of the current photovoltaic energy storage unit is determined according to the following calculation formula. :

[0028]

[0029] in, This represents the remaining energy of the MA-th first energy storage module in the current photovoltaic energy storage unit; MA represents the average remaining energy of all first energy storage modules in the current photovoltaic energy storage unit; MA = 1......L, where L is the total number of first energy storage modules in the current photovoltaic energy storage unit;

[0030] The average coordinated power of the current photovoltaic energy storage unit is determined according to the following calculation formula. :

[0031]

[0032] in, = L× ; This indicates the first preset average remaining energy reference deviation of the photovoltaic energy storage unit. This indicates the allowable deviation of the average remaining energy within the photovoltaic energy storage unit. This represents the residual energy deviation ratio coefficient of the current photovoltaic energy storage unit.

[0033] In one or more embodiments, it further includes:

[0034] The remaining energy and average remaining energy of the second energy storage module in the current pure energy storage unit are obtained in real time, and the actual remaining energy deviation of the current pure energy storage unit is determined.

[0035] The average coordinated power of the current pure energy storage unit is determined based on the actual remaining energy deviation and the second preset average remaining energy reference deviation in the current pure energy storage unit.

[0036] The current pure energy storage unit obtains the charging and discharging mode from the energy management system, and determines the charging and discharging power demand of the second converter in the current pure energy storage unit based on the average coordinated power and charging and discharging power demand in the current pure energy storage unit.

[0037] In one or more embodiments, the actual remaining energy deviation of the current pure energy storage unit is determined according to the following calculation formula. :

[0038]

[0039] in, This represents the remaining energy of the MB-th second energy storage module in the current pure energy storage unit; MB represents the average remaining energy of all second energy storage modules in the current pure energy storage unit; MB = 1......K, where K is the total number of second energy storage modules in the current pure energy storage unit;

[0040] The average coordinated power of the current pure energy storage unit is determined according to the following calculation formula. :

[0041]

[0042] in, = K× ; This indicates the second preset average remaining energy reference deviation of the currently described pure energy storage unit; This indicates the allowable deviation of the average remaining energy within the currently described pure energy storage unit; This represents the residual energy deviation ratio coefficient of the current pure energy storage unit.

[0043] Compared with the prior art, the technical solution of this application has the following beneficial technical effects:

[0044] In the aforementioned photovoltaic energy storage system and its energy management method, the introduction of a DC-DC converter into the photovoltaic energy storage unit enables the direct conversion of electrical energy generated by the photovoltaic power station into energy suitable for storage in energy storage containers, reducing the number of power flow loops and improving overall efficiency. By adding pure energy storage units to the existing photovoltaic energy storage architecture, a supplementary photovoltaic energy storage system with increased storage capacity is achieved. This allows for the addition of energy storage containers during operation to compensate for the capacity decay of existing containers, ensuring the continuous stability of the system capacity. Simultaneously, the energy management system manages the charging and discharging of the photovoltaic and pure energy storage units based on their remaining power, the remaining power of the pure energy storage units, and the output power of the DC-DC converter. This achieves balance control of remaining energy deviation, maximizing the consistency of remaining energy across all energy storage units and extending the lifespan of the energy storage batteries. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the architecture topology of a photovoltaic energy storage system in a related technology;

[0046] Figure 2 This is a schematic diagram of the architectural topology of a photovoltaic energy storage system in another related technology;

[0047] Figure 3 This is a schematic diagram of a photovoltaic energy storage system in one embodiment of this application;

[0048] Figure 4 for Figure 3 A schematic diagram of the architecture topology of a photovoltaic energy storage system;

[0049] Figure 5 This is a flowchart illustrating an energy management method for a photovoltaic energy storage system according to one embodiment of this application.

[0050] Figure 6 This is a flowchart illustrating an energy management method for a photovoltaic energy storage system according to another embodiment of this application.

[0051] Figure 7 This is a flowchart illustrating the energy management method of a photovoltaic energy storage system in another embodiment of this application. Detailed Implementation

[0052] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0054] It should be noted that when one element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediary element. In the following embodiments, "connection" should be understood as "electrical connection," "communication connection," etc., if the connected circuits, units, units, etc., have the transmission of electrical signals or data between them.

[0055] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” or “having,” etc., specify the presence of the stated feature, whole, step, operation, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0056] In related technologies, Figure 1 The large-scale photovoltaic power plants shown face the problem of low photovoltaic energy storage efficiency when a higher proportion of energy is allocated to energy storage. Figure 2 The large-scale photovoltaic power plants shown can improve efficiency, but when increasing integration or reducing costs, a high proportion of energy storage power plants may lead to... Figure 2 Some energy storage containers lack DC-DC converters and photovoltaic (PV) panel connections; another scenario involves users requiring 100% capacity consistency throughout the lifespan, necessitating the addition of separate energy storage containers in earlier years to compensate for battery degradation. These additional containers often lack DC-DC converters and PV panel connections. For these reasons, power plants are often divided into pure energy storage zones and energy storage zones with integrated PV. This shift presents significant challenges to power plant energy management. Traditional power allocation primarily focuses on energy matching between PV and storage, maximizing solar energy utilization, but fails to address the coordination between pure energy storage and PV-integrated energy storage.

[0057] Based on this, embodiments of this application provide a photovoltaic energy storage system and energy management method, which can achieve continuous and stable system capacity while ensuring the consistency of energy coordination in the energy storage system.

[0058] See Figure 3 and Figure 4 , Figure 3 A schematic diagram of a photovoltaic energy storage system according to an embodiment of this application is shown; Figure 4 It shows Figure 3 A schematic diagram of the architecture topology of a photovoltaic energy storage system.

[0059] An embodiment of this application provides a photovoltaic energy storage system, comprising: at least one photovoltaic energy storage unit, at least one pure energy storage unit, an energy management system, and a high-voltage distribution cabinet; a DC-DC converter is introduced into the photovoltaic energy storage unit to convert photovoltaic power generation from DC to DC. The photovoltaic energy storage unit is electrically connected to the high-voltage distribution cabinet to achieve bidirectional power flow; the pure energy storage unit is also electrically connected to the high-voltage distribution cabinet to achieve bidirectional power flow; the high-voltage distribution cabinet is connected to the power grid. Based on a preset charging and discharging mode, the energy management system manages the charging and discharging of the photovoltaic energy storage unit and the pure energy storage unit according to the remaining power of the photovoltaic energy storage unit, the remaining power of the pure energy storage unit, and the output power of the DC-DC converter, to achieve residual energy deviation balance control.

[0060] It should be noted that the photovoltaic energy storage system is a hybrid energy storage power station with a photovoltaic energy storage area and a pure energy storage area. The photovoltaic energy storage area includes at least one photovoltaic energy storage unit, and the pure energy storage area includes at least one pure energy storage unit. A photovoltaic energy storage unit refers to a unit that generates electricity through photovoltaic power, can store energy, and supply power to the grid. A pure energy storage unit refers to a unit that can store energy and supply power to the grid. The photovoltaic energy storage area is connected to the high-voltage distribution cabinet via a power cable, enabling bidirectional flow of electrical energy between the photovoltaic energy storage area and the high-voltage distribution cabinet. Similarly, the pure energy storage area is connected to the high-voltage distribution cabinet via a power cable, enabling bidirectional flow of electrical energy between the high-voltage distribution cabinets within the pure energy storage area. The high-voltage distribution cabinet is connected to the power grid via a power cable, enabling the flow of electrical energy between the photovoltaic energy storage area, the pure energy storage area, and the power grid. The energy management system is connected to the photovoltaic energy storage area, the pure energy storage area, and the high-voltage distribution cabinet via signal lines, enabling communication between them. Power cables facilitate the transmission of electrical energy between these modules. In this embodiment, both photovoltaic energy storage units and pure energy storage units are configured as multiple units. In other embodiments, both photovoltaic energy storage units and pure energy storage units can be configured as one unit.

[0061] Specifically, the high-voltage ports of each photovoltaic energy storage unit are connected to a high-voltage distribution cabinet via power cables. The high-voltage distribution cabinet is connected to the power grid. Similarly, the high-voltage ports of each pure energy storage unit are also connected to the high-voltage distribution cabinet via power cables. The photovoltaic energy storage units generate electricity and, after DC-DC conversion, can store a portion of the energy, while simultaneously enabling energy flow with the high-voltage distribution cabinet. The high-voltage distribution cabinet can transmit a portion of the energy output from the photovoltaic energy storage units to the power grid, and another portion to the pure energy storage units for storage. The pure energy storage units are used for energy storage or to supply power to the grid through the high-voltage distribution cabinet. In other words, the electricity generated by each photovoltaic energy storage unit can be supplied to the grid, or it can be stored by both the photovoltaic energy storage units and the pure energy storage units. When power is needed to supply the grid, both the photovoltaic energy storage units and the pure energy storage units can discharge.

[0062] In this embodiment, a DC-DC converter is introduced into the photovoltaic energy storage unit, which can directly convert the electrical energy generated by the photovoltaic power station into energy suitable for storage in the energy storage container, reducing the power flow loop and improving overall efficiency. Based on the photovoltaic energy storage architecture, a pure energy storage unit is added to realize a photovoltaic energy storage system with supplementary storage capacity. This allows for the addition of energy storage containers during use to compensate for the capacity decay of the original containers, ensuring the continuous stability of the system capacity. Simultaneously, based on the charging / discharge mode of the dispatch center, the energy management system performs charging / discharging management on each photovoltaic energy storage unit and each pure energy storage unit according to the remaining power of each photovoltaic energy storage unit, the remaining power of each pure energy storage unit, and the output power of each DC-DC converter. This achieves residual energy deviation balance control, striving to achieve consistency in the remaining energy of each energy storage unit, which is beneficial for extending the life of the energy storage battery.

[0063] Continue reading Figure 4 In some embodiments, the photovoltaic energy storage unit includes a photovoltaic cell array, a DC-DC converter, a first energy storage module, a first converter, a first transformer, and a first coordination controller. The photovoltaic cell array generates electricity, which is then converted by the DC-DC converter and output to the corresponding first energy storage module and the corresponding first converter. The first converter performs power conversion on the electricity and outputs it to the first transformer, which then steps up the voltage and transmits the electricity to a high-voltage distribution cabinet. The first energy storage module is used for energy storage or discharge. The first coordination controller is connected to the energy management system and is used to control the DC-DC converter, the first energy storage module, and the first converter based on a residual energy deviation balance control strategy.

[0064] It should be noted that a photovoltaic cell pack consists of one or more photovoltaic modules connected in series. In this embodiment, the photovoltaic cell pack, DC-DC converter, first energy storage module, and first converter of the photovoltaic energy storage unit are all configured as multiple and correspond one-to-one, while the first transformer and first coordination controller of the same photovoltaic energy storage unit are all configured as one. In other embodiments, the photovoltaic cell pack, DC-DC converter, first energy storage module, and first converter of the photovoltaic energy storage unit can all be configured as one, and the first transformer and first coordination controller of the same photovoltaic energy storage unit can all be configured as one; or, the photovoltaic cell pack, DC-DC converter, first energy storage module, and first converter of the photovoltaic energy storage unit can all be configured as multiple, and the first transformer and first coordination controller of the same photovoltaic energy storage unit can all be configured as two or three, etc. Each combination of first transformer and first coordination controller corresponds to a combination of one or more photovoltaic cell packs, DC-DC converters, first energy storage modules, and first converters. The specific configuration can be determined according to the actual situation.

[0065] In the same photovoltaic energy storage unit, each photovoltaic cell array and its corresponding DC-DC converter are connected by a power cable. Each DC-DC converter is connected to its corresponding first energy storage module by a power cable. Each first energy storage module is connected to its corresponding first converter by a power cable. Each first converter is connected to its first transformer by a power cable. The first transformer is connected to its high-voltage distribution cabinet by a power cable. The power cables enable the transmission of electrical energy between the above modules.

[0066] In the same photovoltaic energy storage unit, the first coordination controller is connected to each DC-DC converter via signal lines, and the first coordination controller is also connected to the energy management system via signal lines. The DC-DC converters transmit their current output power and maximum photovoltaic power generation signals to the first coordination controller, and the first coordination controller transmits the maximum allowable DC-DC power to the current DC-DC converter. The first coordination controller is connected to each first converter via signal circuits. The first converters transmit their current charging power signal / discharging power signal to the energy management system through the first coordination controller. In this embodiment, the energy management system can determine whether the current first converter is operating normally based on the deviation between the set charging power demand / discharging power demand for the current first converter and the currently received charging power / discharging power.

[0067] The first coordination controller also transmits the current allowed charging power / allowed discharging power of the photovoltaic energy storage unit and the remaining energy signal of the photovoltaic energy storage unit to the energy management system. The energy management system sends the charging mode / discharging mode and the charging power demand / discharging power demand signal for the current photovoltaic energy storage unit to the first coordination controller. In this embodiment, the energy management system ensures that the set charging power demand / discharging power demand signal does not exceed the allowed charging power / discharging power based on the current allowed charging power / allowed discharging power of the photovoltaic energy storage unit.

[0068] The first coordination controller is connected to each of the first energy storage modules via signal lines. In this embodiment, the first energy storage module can be a lithium battery energy storage container or a single cluster of lithium battery energy storage containers; the first energy storage module can transmit its current allowable charging power / allowable discharging power and remaining energy signals to the first coordination controller. In this embodiment, before controlling the corresponding first energy storage module to charge or discharge via the first converter, the first coordination controller can determine the charging demand power / discharge demand power set for the first converter based on the current allowable charging power / discharge power of the first energy storage module. If the demand power / discharge demand power does not exceed the allowable charging power / discharge power of the corresponding first energy storage module, the first converter sends the charging demand power / discharge demand power to the first converter, which then controls the corresponding first energy storage module to charge or discharge. If the charging demand power / discharge demand power set for the first converter exceeds the allowable charging power / discharge power of the corresponding first energy storage module, the charging demand power / discharge demand power set for the first converter is updated based on the allowable charging power / discharge power of the corresponding first energy storage module, and the updated charging demand power / discharge demand power is sent to the first converter.

[0069] Specifically, the photovoltaic (PV) cell array generates electricity, which is then converted by a DC-DC converter and output to corresponding first energy storage modules and corresponding first converters. The first converters then convert the electricity into power and output it to a first transformer. The transformer then steps up the voltage and transmits the electricity to a high-voltage distribution cabinet, where it is either fed into the grid or transmitted to a pure energy storage unit. The first energy storage modules are used for energy storage or discharge. The first coordination controller, based on the charging / discharging mode and power demand signals issued by the energy management system for the current PV energy storage unit, and based on the remaining energy of each first energy storage module and the output power of the corresponding DC-DC converter, dynamically controls the corresponding first converter using a residual energy deviation balance control strategy to control the charging / discharging power of the first converter. This reasonable control of the charging / discharging power of each first converter prevents the risks of overcharging and discharging of a single first energy storage module, helping to improve the consistency between energy storage systems.

[0070] Continue reading Figure 4 In some embodiments, the pure energy storage unit includes a second energy storage module, a second converter, a second transformer, and a second coordination controller. The second energy storage module and the second converter are connected. One side of the second converter is sequentially connected to the second transformer and the second coordination controller. The second coordination controller is connected to a high-voltage distribution cabinet. The second energy storage module is used for energy storage or discharge. The second coordination controller is used to control the second energy storage module and the second converter based on a residual energy deviation balance control strategy.

[0071] It should be noted that in this embodiment, the second energy storage module and the second converter of the pure energy storage unit are both configured as multiple, while the second transformer and the second coordination controller of the same pure energy storage unit are both configured as one. In other embodiments, the second energy storage module and the second converter of the pure energy storage unit can both be configured as one, and the second transformer and the second coordination controller of the same pure energy storage unit can both be configured as one; or, the second energy storage module and the second converter of the pure energy storage unit can both be configured as multiple, and the second transformer and the second coordination controller of the same pure energy storage unit can both be configured as two or three, etc. The specific configuration can be determined according to the actual situation.

[0072] In this embodiment, the second energy storage module is connected to the second converter via a power cable; the second converter is connected to the second transformer via a power cable; the second transformer is connected to the high-voltage distribution cabinet via a power cable; the power cables enable power transmission between these modules. The second coordination controller is connected to the second converter via a signal circuit; the second coordination controller is connected to the energy management system via a signal line. The second converter can transmit the current charging / discharging power signal to the energy management system through the second coordination controller. In this embodiment, the energy management system can determine whether the second converter is operating normally based on the deviation between the set charging / discharging power demand and the currently received charging / discharging power.

[0073] The second coordination controller also transmits the allowable charging / discharging power and remaining energy signal of the current pure energy storage unit to the energy management system. The energy management system transmits the charging / discharging mode and the charging / discharging power demand signal for the current pure energy storage unit to the second coordination controller. In this embodiment, the energy management system can ensure that the set charging / discharging power demand signal does not exceed the allowable charging / discharging power based on the allowable charging / discharging power of the current pure energy storage unit. In this embodiment, the second coordination controller and the second energy storage module are connected via signal lines. The second energy storage module can be a lithium battery energy storage container or a single cluster of lithium battery energy storage containers; the second energy storage module transmits the allowable charging / discharging power and remaining energy signal to the second coordination controller. In this embodiment, before controlling the corresponding second energy storage module to charge or discharge via the second converter, the second coordination controller can determine the charging demand power / discharge demand power set for the second converter based on the current allowable charging power / discharge power of the second energy storage module. If the demand power / discharge demand power does not exceed the allowable charging power / discharge power of the corresponding second energy storage module, the controller sends the charging demand power / discharge demand power to the second converter, which then controls the corresponding second energy storage module to charge or discharge. If the charging demand power / discharge demand power set for the second converter exceeds the allowable charging power / discharge power of the corresponding second energy storage module, the controller updates the charging demand power / discharge demand power set for the second converter based on the allowable charging power / discharge power of the corresponding second energy storage module, and sends the updated charging demand power / discharge demand power to the second converter.

[0074] Specifically, the second energy storage module is used for energy storage or discharging, i.e., charging or discharging. In the charging mode of the second energy storage module, the second transformer receives part of the electrical energy transmitted from the high-voltage distribution cabinet and, after conversion by each second converter, transmits the electrical energy to the corresponding second energy storage module to achieve the purpose of energy storage. In the discharging mode of the second energy storage module, the second energy storage module outputs electrical energy, which, after conversion by the second converter and the second transformer, is output to the high-voltage distribution cabinet to achieve power supply to the grid. The second coordination controller dynamically controls the corresponding second converter based on the remaining energy of each second energy storage unit and the remaining energy deviation balance control strategy to control the charging / discharging power of the second converter. In this way, by reasonably controlling the charging / discharging power of each second converter, the risks caused by overcharging and discharging of a single second energy storage module are prevented, which helps to improve the consistency between energy storage systems.

[0075] The photovoltaic energy storage system in this embodiment adopts a zoned architecture, with the photovoltaic energy storage zone and the pure energy storage zone respectively connected to high-voltage switchgear, and energy and information are coordinated and scheduled through an energy management system. Simultaneously, by coordinating the signal transmission between the controller and the energy management system, the power and mode of photovoltaic power generation and energy storage charging and discharging are precisely controlled, thereby achieving more efficient and flexible system energy management.

[0076] Based on the same inventive concept, an embodiment of this application also provides an energy management method for a photovoltaic energy storage system. This energy management method adopts a hierarchical control approach, which is divided into a residual energy deviation balance control strategy based on the energy management system level for photovoltaic energy storage areas and pure energy storage areas, and a residual energy deviation balance control strategy based on the coordination controller level for the internal unit modules of photovoltaic energy storage areas and pure energy storage areas.

[0077] See Figure 5 , Figure 5 A flowchart illustrating an energy management method for a photovoltaic energy storage system according to an embodiment of this application is shown.

[0078] An embodiment of this application also provides an energy management method for a photovoltaic energy storage system, which includes the following steps:

[0079] S501. Real-time acquisition of the remaining energy of photovoltaic energy storage units, the remaining energy of pure energy storage units, and the average remaining power of the power station to determine the actual remaining energy deviation of the power station.

[0080] In some embodiments, the actual power plant residual energy deviation can be determined according to the following calculation formula. :

[0081] ;

[0082] in, This represents the remaining energy of the A-th photovoltaic energy storage unit; This represents the remaining energy of the Bth pure energy storage unit; The average remaining energy of the power station is represented by A = 1...N, where N is the total number of photovoltaic energy storage units; B = 1...M, where M is the total number of pure energy storage units. In this embodiment, the average remaining energy of the power station... .

[0083] Specifically, the remaining energy (SOE) of the photovoltaic energy storage unit is obtained from the first coordination controller of the photovoltaic energy storage unit in the photovoltaic energy storage area via communication. A That is, the remaining energy SOE of the Ath photovoltaic energy storage unit. A And obtain the total output power (POWER) of all DC-DC converters in the current photovoltaic energy storage unit. DCDC_AAdditionally, the remaining energy (SOE) of the pure energy storage unit is obtained from the second coordination controller of the pure energy storage unit in the pure energy storage area via communication. B That is, the remaining energy SOE of the Bth pure energy storage unit. B Based on the remaining energy of the photovoltaic energy storage unit Residual energy of pure energy storage units and the average remaining power of the power station Determine the actual remaining energy deviation of the power plant .

[0084] S502. Determine the average coordinated power of the power station based on the actual residual energy deviation of the power station and the preset total reference deviation of the residual energy of the power station.

[0085] In some embodiments, the average coordinated power of the power plant can be determined according to the following calculation formula. :

[0086]

[0087] in, =(M+N)× ; This indicates the total reference deviation of the power plant's remaining energy. Indicates the allowable deviation of the power plant's remaining energy; This represents the average coordinated power coefficient of the energy management system.

[0088] Specifically, the allowable deviation of remaining energy (SOE) of the power plant is obtained from the user settings interface on the client side. delt_base Obtain the maximum value of the power plant's remaining energy SOE. max SOC minimum value SOE min Based on the actual remaining energy deviation of the power plant The total reference deviation from the preset power plant surplus energy Determine the average coordinated power of the power plant .

[0089] S503 The energy management system obtains the charging and discharging modes from the dispatch center and determines the charging and discharging power requirements of the photovoltaic energy storage unit and the pure energy storage unit based on the output power of all DC-DC converters, the average coordinated power of the power station, and the preset reference charging and discharging power.

[0090] In some embodiments, if the charging / discharging mode is the allowable discharge mode, the discharge demand power of the current photovoltaic energy storage unit is determined based on the output power of all DC-DC converters, the average coordinated power, and a preset reference discharge power, and based on the difference between the remaining energy of the current photovoltaic energy storage unit and the average remaining power of the power station. Simultaneously, the discharge demand power of the current pure energy storage unit is determined based on the output power of all DC-DC converters, the average coordinated power, and the preset reference discharge power, and based on the difference between the remaining energy of the current pure energy storage unit and the average remaining power of the power station. Thus, the energy management system transmits the discharge demand power and discharge mode of the current photovoltaic energy storage unit to the corresponding first coordinated controller via a signal, and transmits the discharge demand power and discharge mode of the current pure energy storage unit to the corresponding second coordinated controller via a signal, and returns to step S501.

[0091] If the charging / discharging mode is the allowed charging mode, the charging power requirement of the current photovoltaic energy storage unit is determined based on the output power of all DC-DC converters, the average coordinated power, and the preset reference charging power, and based on the difference between the average remaining power of the power station and the remaining energy of the current photovoltaic energy storage unit. Simultaneously, the charging power requirement of the current pure energy storage unit is determined based on the output power of all DC-DC converters, the average coordinated power, and the preset reference charging power, and based on the difference between the average remaining power of the power station and the remaining energy of the current pure energy storage unit. Thus, the energy management system transmits the charging power requirement and charging mode of the current photovoltaic energy storage unit to the corresponding first coordinated controller via signals, and transmits the charging power requirement and charging mode of the current pure energy storage unit to the corresponding second coordinated controller via signals, and returns to step S501.

[0092] In this embodiment, by transmitting key data such as SOE and DC-DC output power of photovoltaic energy storage units and pure energy storage units in real time, the coordination of energy management of each part during operation is ensured. Furthermore, through the residual energy deviation balance control strategy, energy scheduling of photovoltaic energy storage area and pure energy storage area can be realized, improving the storage efficiency of photovoltaic energy. At the same time, it prevents excessive residual energy deviation between each energy storage unit, increases the consistency between each unit, and helps to extend the life of energy storage battery.

[0093] See Figure 6 , Figure 6 A flowchart illustrating an energy management method for a photovoltaic energy storage system according to another embodiment of this application is shown.

[0094] In some embodiments, the energy management method of the photovoltaic energy storage system of this application further includes:

[0095] S601. Real-time acquisition of the remaining energy and average remaining energy of the first energy storage module in the current photovoltaic energy storage unit, and determination of the actual remaining energy deviation of the current photovoltaic energy storage unit.

[0096] In this embodiment, the actual remaining energy deviation of the current photovoltaic energy storage unit can be determined according to the following calculation formula. :

[0097]

[0098] in, This represents the remaining energy of the MA-th first energy storage module in the current photovoltaic energy storage unit; MA represents the average remaining energy of all first energy storage modules in the current photovoltaic energy storage unit; MA = 1......L, where L is the total number of first energy storage modules in the current photovoltaic energy storage unit.

[0099] Specifically, the first coordinating controller of the current photovoltaic energy storage unit obtains the remaining energy SOE of the MA-th first energy storage module in the current photovoltaic energy storage unit through communication. MA MA=1...L, where L is the total number of the first energy storage modules in the current photovoltaic energy storage unit. Furthermore, for ease of subsequent calculations, the first coordinating controller of the current photovoltaic energy storage unit obtains the average remaining energy deviation (SOE) within the photovoltaic energy storage unit from the energy management system. delt_base_A And obtain the output power POWER of the DC-DC converter in the current photovoltaic energy storage unit. DCDC_MA Based on the remaining energy of all the first energy storage modules in the current photovoltaic energy storage unit. The first coordinating controller of the current photovoltaic energy storage unit will control the remaining energy SOE of the current photovoltaic energy storage unit. A The signal is uploaded to the energy management system, and the output power POWER of the DC-DC converter in the current photovoltaic energy storage unit is transmitted. DCDC_MA The signal is uploaded to the energy management system.

[0100] S602. Determine the average coordinated power of the current photovoltaic energy storage unit based on the actual remaining energy deviation in the current photovoltaic energy storage unit and the first preset average remaining energy reference deviation.

[0101] In this embodiment, the average coordinated power of the current photovoltaic energy storage unit can be determined according to the following calculation formula. :

[0102]

[0103] in, = L× ; This indicates the first preset average remaining energy reference deviation of the current photovoltaic energy storage unit; This indicates the allowable deviation of the average remaining energy within the current photovoltaic energy storage unit; This represents the residual energy deviation ratio coefficient of the current photovoltaic energy storage unit.

[0104] S603. The current photovoltaic energy storage unit obtains the charging and discharging mode from the energy management system, and determines the charging and discharging power demand of the first converter in the current photovoltaic energy storage unit based on the output power of the DC-DC converter in the current photovoltaic energy storage unit, the average coordinated power of the current photovoltaic energy storage unit, and the charging and discharging power demand.

[0105] Specifically, the first coordination controller of the current photovoltaic energy storage unit will determine the discharge power demand of the MA-th first converter in the current photovoltaic energy storage unit. The discharge mode is transmitted to the MA-th first converter of the current photovoltaic energy storage unit via a signal, and then returns to step S601 to achieve residual energy deviation balance control of each first energy storage module at the first coordination controller level.

[0106] Specifically, the first coordination controller of the current photovoltaic energy storage unit will target the charging power demand of the MA-th first converter in the current photovoltaic energy storage unit. The charging mode is transmitted to the MA-th first converter of the current photovoltaic energy storage unit via a signal, and then returns to step S601 to achieve residual energy deviation balance control of each first energy storage module at the first coordination controller level.

[0107] In this embodiment, based on the residual energy deviation balance control strategy at the first coordinating controller level, the charging and discharging power of each photovoltaic energy storage unit is dynamically adjusted by calculating the energy reference deviation and average coordinating power to prevent the risks caused by overcharging and discharging of a single photovoltaic energy storage unit and improve the consistency between energy storage systems.

[0108] See Figure 7 , Figure 7 A flowchart illustrating an energy management method for a photovoltaic energy storage system according to another embodiment of this application is shown.

[0109] In some embodiments, the energy management method of the photovoltaic energy storage system of this application further includes the following steps:

[0110] S701. Real-time acquisition of the remaining energy and average remaining energy of the second energy storage module in the current pure energy storage unit, and determination of the actual remaining energy deviation of the current pure energy storage unit.

[0111] In this embodiment, the actual remaining energy deviation of the current pure energy storage unit can be determined according to the following calculation formula. :

[0112]

[0113] in, This represents the remaining energy of the MB-th second energy storage module in the current pure energy storage unit; MB represents the average remaining energy of all second energy storage modules in the current pure energy storage unit; MB = 1......K, where K is the total number of second energy storage modules in the current pure energy storage unit.

[0114] Specifically, the second coordination controller of the current pure energy storage unit obtains the remaining energy (SOE) of the second energy storage module in the current pure energy storage unit through communication. MB To facilitate subsequent calculations, the second coordination controller of the current pure energy storage unit also obtains the average remaining energy deviation (SOE) within the pure energy storage unit from the energy management system. delt_base_B Based on the remaining energy of all secondary energy storage modules in the current pure energy storage unit. The second coordinating controller will convert the remaining SOE of the current pure energy storage unit. B The signal is uploaded to the energy management system.

[0115] S702. Determine the average coordinated power of the current pure energy storage unit based on the actual remaining energy deviation in the current pure energy storage unit and the second preset average remaining energy reference deviation.

[0116] In this embodiment, the average coordinated power of the current pure energy storage unit can be determined according to the following calculation formula. :

[0117]

[0118] in, = K× ; This indicates the second preset average remaining energy reference deviation of the current pure energy storage unit; This indicates the allowable deviation of the average remaining energy within the current pure energy storage unit; This represents the residual energy deviation ratio coefficient of the current pure energy storage unit.

[0119] S703. The current pure energy storage unit obtains the charging and discharging mode from the energy management system, and determines the charging and discharging power demand of the second converter in the current pure energy storage unit based on the average coordinated power and charging and discharging power demand in the current pure energy storage unit.

[0120] Specifically, the second coordination controller of the current pure energy storage unit will target the discharge power demand of the MB-th second converter in the current pure energy storage unit. The discharge mode is transmitted to the MB second converter of the current photovoltaic energy storage unit via a signal and then returned to step S701 to achieve residual energy deviation balance control of each second energy storage module at the second coordination controller level.

[0121] Specifically, the second coordination controller of the current pure energy storage unit will target the charging power demand of the MB-th second converter in the current pure energy storage unit. The charging mode is transmitted to the MB-th second converter of the current pure energy storage unit via a signal, and then returns to step S701 to achieve residual energy deviation balance control of each second energy storage module at the second coordination controller level.

[0122] In this embodiment, based on the residual energy deviation balance control strategy at the second coordination controller level, the charging and discharging power of each pure energy storage unit is dynamically adjusted by calculating the energy reference deviation and average coordination power to prevent the risks caused by overcharging and discharging of a single pure energy storage unit and improve the consistency between energy storage systems.

[0123] In the energy management method of the photovoltaic energy storage system in this embodiment, a hierarchical control energy management strategy is adopted, including a residual energy deviation balance control strategy based on the energy management system level and a residual energy deviation balance control strategy based on the coordination controller level. This energy management strategy enables energy scheduling between the photovoltaic energy storage area and the pure energy storage area, improving the storage efficiency of photovoltaic energy while preventing excessive residual energy deviation between energy storage units, increasing consistency among energy storage units, and extending the lifespan of energy storage batteries. Furthermore, by transmitting key data such as the charging and discharging power and SOE of the photovoltaic energy storage units and pure energy storage units in real time, coordination of energy management in each part is ensured during operation, achieving the target control of the average residual energy SOE of each energy storage unit. By calculating the energy reference deviation and average coordinated power, the charging and discharging power of each energy storage unit is dynamically adjusted to prevent the risks caused by overcharging and discharging of a single energy storage unit and improve the consistency between energy storage systems.

[0124] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A photovoltaic energy storage system, characterized in that, include: The system includes at least one photovoltaic energy storage unit, at least one pure energy storage unit, an energy management system, and a high-voltage switchgear; the photovoltaic energy storage unit incorporates a DC-DC converter to convert photovoltaic power generation to DC-DC conversion. The photovoltaic energy storage unit is electrically connected to the high-voltage distribution cabinet to achieve bidirectional flow of electrical energy; the pure energy storage unit is electrically connected to the high-voltage distribution cabinet to achieve bidirectional flow of electrical energy; the high-voltage distribution cabinet is connected to the power grid. The remaining energy of the photovoltaic energy storage unit, the remaining energy of the pure energy storage unit, and the average remaining power of the power station are acquired in real time to determine the actual remaining energy deviation of the power station. Based on the actual remaining energy deviation of the power station and the preset total reference deviation of the remaining energy of the power station, the average coordinated power of the power station is determined. The energy management system obtains the charging and discharging mode from the dispatch center and performs charging and discharging management on the photovoltaic energy storage unit and the pure energy storage unit based on the output power of all the DC-DC converters, the average coordinated power of the power station, and the preset reference charging and discharging power. The charging and discharging power demand of the photovoltaic energy storage unit and the charging and discharging power demand of the pure energy storage unit are determined to achieve remaining energy deviation balance control.

2. The photovoltaic energy storage system according to claim 1, characterized in that, The photovoltaic energy storage unit includes a photovoltaic cell array, a DC-DC converter, a first energy storage module, a first converter, a first transformer, and a first coordination controller; The photovoltaic cell array is used to generate electricity and outputs electrical energy. After being converted by a DC-DC converter, the electrical energy is output to the corresponding first energy storage module and the corresponding first converter, so that the first converter converts the electrical energy into power and outputs it to the first transformer. The first transformer then steps up the voltage and transmits the electrical energy to the high-voltage distribution cabinet. The first energy storage module is used for energy storage or discharge. The first coordination controller is connected to the energy management system and is used to control the DC-DC converter, the first energy storage module and the first converter based on the residual energy deviation balance control strategy.

3. The photovoltaic energy storage system according to claim 1, characterized in that, The pure energy storage unit includes a second energy storage module, a second converter, a second transformer, and a second coordination controller. The second energy storage module and the second converter are connected together. The second transformer and the second coordination controller are connected in sequence to one side of the second converter. The second coordination controller is connected to the high-voltage distribution cabinet. The second energy storage module is used for energy storage or discharge; the second coordination controller is used to control the second energy storage module and the second converter based on the residual energy deviation balance control strategy.

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