Optical storage integrated system based on dynamic reconfigurable technology

Abstract

The invention discloses an optical storage integrated system based on a dynamic reconfigurable technology, which belongs to the technical field of energy storage of a new energy power system and comprises an optical storage component, a digital energy network card and a digital energy exchange system. Each light storage assembly comprises a photovoltaic assembly and an energy storage assembly, the photovoltaic assembly and the energy storage assembly are connected in parallel, and the photovoltaic assembly is used for supplying power to the energy storage assembly; the digital energy exchange system is used for formulating and lowering a dynamic reconfigurable strategy of the light storage array; and the digital energy network card communicates with the digital energy exchange system, uploads the state information of the optical storage assembly in real time, and receives and executes the strategy of the digital energy exchange system. According to the invention, fine control of photovoltaic module and battery module level granularity is supported, total-factor intelligent collaborative scheduling of photovoltaic, energy storage, an inverter, a power grid, a load and a power generation prediction model is realized through a dynamic reconfigurable technology, and the income-cost ratio of the whole system is maximized.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage in new energy power systems, and particularly to a photovoltaic-storage integrated system based on dynamic reconfiguration technology. Background Art

[0002] As a clean energy technology, photovoltaic power generation faces a series of challenges in the process of popularization and application. First of all, the power generation of photovoltaic systems is strictly restricted by installation conditions. The arrangement of roof components must take into account factors such as obstacle blockage and shadow occlusion to ensure the consistency of the orientation and inclination of components within the same string. Otherwise, series mismatch of the string will occur, affecting the overall power generation. In the industrial and commercial scenarios, as the development of high-quality roof resources approaches saturation, the remaining roofs are difficult to utilize due to various shadow occluders such as parapets and billboards, which restricts the further development of photovoltaic power generation and affects the overall benefits of customers.

[0003] In addition, there is a so-called "barrel effect" in the power generation of photovoltaic components, that is, the working currents of components connected in series in the same string must be kept consistent. Any mismatch will cause the operating point to shift, thereby reducing the output power of the entire string. The reasons for mismatch are diverse, including manufacturing tolerances during component production, environmental factors such as dust, clouds, fallen leaves, and bird droppings, as well as fixed occluders in system design such as chimneys, dormer windows, and trees. As the components age, mismatch problems will also occur during the attenuation process.

[0004] In terms of safety and operation and maintenance, the DC-side photovoltaic panel voltage of rooftop photovoltaic projects can reach 600V to 1000V, which poses potential risks to construction and operation and maintenance personnel as well as the owners. In case of emergencies such as fires, the high voltage carried by the photovoltaic array makes it difficult for rescue personnel to conduct rooftop disaster relief. Therefore, continuous exploration and innovation are still needed in aspects such as improving efficiency, reducing costs, enhancing safety, and optimizing operation and maintenance for photovoltaic power generation.

[0005] The integrated design solution of photovoltaic plus energy storage can improve energy utilization efficiency and system flexibility. By combining photovoltaic power generation with an energy storage system, excess electric energy can be stored during sufficient sunlight for use when sunlight is insufficient or at night, thereby reducing dependence on the power grid and improving the self-sufficiency ability. This design also helps to balance the power grid load, reduce the power grid fluctuations caused by the intermittency of photovoltaic power generation, and enhance the stability and reliability of power supply. In addition, the integrated design can optimize system configuration, reduce costs, simplify the installation and maintenance processes, make the photovoltaic energy storage system more economical and efficient, and contribute to the wide application of renewable energy.

[0006] Currently, there are four mainstream integrated design solutions for photovoltaic energy storage systems, such as Figures 1 - 4As shown. These design schemes are essentially independent operations of photovoltaic and energy storage systems. The photovoltaic and energy storage systems can only cooperate at the system level and fail to achieve a deeper integration design with finer granularity. The battery balancing basically adopts a passive balancing mode or an active balancing method using a DC-DC circuit, with limited improvement in investment returns and unable to truly achieve safety control of current-level balancing. Summary of the Invention

[0007] The present invention aims at the deficiencies of the existing technology and provides an integrated photovoltaic and energy storage system based on dynamic reconfigurable technology.

[0008] The technical solution of the present invention to solve the above technical problems is as follows:

[0009] An integrated photovoltaic and energy storage system based on dynamic reconfigurable technology includes a photovoltaic and energy storage component, a digital energy network card, and a digital energy exchange system;

[0010] A plurality of the photovoltaic and energy storage components form a photovoltaic and energy storage array of m×n×k, where m is the number of strings, n is the number of photovoltaic components connected in series in a string, and k is the number of parallel branches in each string; each of the photovoltaic and energy storage components includes a photovoltaic component and an energy storage component, and the photovoltaic component and the energy storage component are connected in parallel, and the photovoltaic component is used to supply power to the energy storage component;

[0011] The digital energy exchange system is used to formulate and issue a dynamic reconfiguration strategy for the photovoltaic and energy storage array;

[0012] The digital energy network card communicates with the digital energy exchange system through an information bus, and uploads the status information of the photovoltaic and energy storage components in real time, and receives and executes the strategy of the digital energy exchange system.

[0013] Further, the status information of the photovoltaic and energy storage components includes four types. The first type is that the photovoltaic component is online and the energy storage component is offline; the second type is that the photovoltaic component is online and the energy storage component is online for charging; the third type is that the photovoltaic component is offline and the energy storage component is online; the fourth type is that the photovoltaic component is offline and the energy storage component is offline.

[0014] Further, whether each of the photovoltaic components and the energy storage components is cut into the circuit is controlled by a power electronic switch.

[0015] Further, the energy storage component is a battery sub-string, and the battery sub-string includes B+2 series-connected battery cells, where B is defined as the minimum value of the number of battery cells simultaneously cut into the circuit in the battery sub-string.

[0016] Further, in the series direction, the number of battery cells connected into the circuit is any one of B, B+1, and B+2.

[0017] Further, when the photovoltaic and energy storage assembly is in the first state, i.e., the photovoltaic assembly is online and the energy storage assembly is offline, when the digital energy exchange system detects that the energy storage capacity is less than the preset energy storage value and needs to be charged, and at the same time the power generation power of the photovoltaic assembly is greater than the rated power generation power, the energy storage assembly is switched into the circuit. At this time, the voltage of the battery monomer switched into the circuit needs to be less than the output voltage of the photovoltaic assembly.

[0018] Further, when the photovoltaic and energy storage assembly is in the second state, i.e., the photovoltaic assembly is online and the energy storage assembly is in the online charging state, after the digital energy exchange system detects that the voltages of B+2 battery monomers reach the charging cut-off voltage, the energy storage assembly is switched out of the circuit and enters the first state, i.e., the photovoltaic assembly is online and the energy storage assembly is offline.

[0019] Further, in the mode of B+1 battery monomers or B battery monomers, the photovoltaic assembly charges the battery sub-string; in the mode of B+2 battery monomers or B+1 battery monomers, the battery sub-string replaces the shaded or faulty photovoltaic assembly.

[0020] Further, in any case, the voltage of the energy storage assembly is less than the voltage of the photovoltaic assembly.

[0021] Further, the digital energy exchange system detects the voltages of the photovoltaic assembly and the energy storage assembly in real time, avoids reverse charging of the energy storage assembly through dynamic reconfiguration technology, and controls the pressure difference range.

[0022] In summary, compared with the prior art, the beneficial effects of the above technical solutions are as follows:

[0023] The present invention can realize a component-level fine-grained control mode, support the collaborative control between each photovoltaic component and energy storage component; detect the voltages of the photovoltaic component and the battery sub-string in real time through the digital energy exchange system, avoid reverse charging of the battery sub-string through dynamic reconfigurable technology, and control the pressure difference range. The system state is synchronized in microseconds in real time to achieve synchronous operation between components, and reduce the transient effects caused by the dynamic access and disconnection of components from the circuit; realize the full-element intelligent collaborative scheduling of photovoltaic, energy storage, inverter, power grid, load, and power generation prediction models through dynamic reconfigurable technology, and maximize the benefit-cost ratio of the entire system. Description of the Drawings

[0024] Figure 1 Schematic diagram of independent photovoltaic + energy storage;

[0025] Figure 2 Schematic diagram of AC-side coupled photovoltaic + energy storage;

[0026] Figure 3 Schematic diagram of DC-side loosely coupled photovoltaic + bidirectional charging energy storage;

[0027] Figure 4 Schematic diagram of a photovoltaic + photovoltaic-only charging energy storage system with a tightly coupled DC side;

[0028] Figure 5 Schematic diagram of an integrated photovoltaic and energy storage system based on dynamic reconfigurable technology;

[0029] Figure 6 Schematic diagram of the state transition of a photovoltaic and energy storage component. Specific implementation manners

[0030] The principles and features of the present invention will be described below in conjunction with all the drawings. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0031] An embodiment of the present invention discloses an integrated photovoltaic and energy storage system based on dynamic reconfigurable technology.

[0032] How to eliminate the "short board effect" of the battery system is the core technical issue in the development of the energy storage industry. At present, the main means in the industry to solve the "short board effect" is to pursue the consistency of battery monomers during production and use, which will inevitably lead to higher and higher marginal costs, and at the same time, the "short board effect" of the battery system cannot be fundamentally eliminated. Therefore, we first proposed the dynamic reconfigurable battery (DRB) energy storage technology based on energy digitization, which changed the application paradigm of fixed series-parallel connections since the invention of batteries. The physical connection between batteries was changed from the rigid connection of traditional fixed series-parallel to a flexible connection controlled by a program. By controlling the time for each battery to access the charge and discharge circuit, an "as much as possible" battery energy management and control mode was achieved. Then, we proposed an energy control and system-level intrinsic safety control method based on dynamic reconfigurable battery energy storage technology, represented the energy control problem as an optimization problem, and analyzed the intrinsic safety control method based on controllable series-parallel technology. A large amount of actual operation data shows that the dynamic reconfigurable battery energy storage technology can greatly improve the safety and energy efficiency of the battery energy storage system, providing a new path for building a large-scale, long-life and low-cost battery energy storage system.

[0033] Following the development trend of intelligent photovoltaic technology, the present invention proposes a new innovative solution for integrated photovoltaic and energy storage to achieve high efficiency, intelligence and cost optimization of the photovoltaic energy storage system. The core objectives of the embodiments of the present invention include an integrated design based on dynamic reconfiguration at the DC side and component level to achieve fine-grained control at the component level. Using advanced dynamic reconfigurable technology to realize intelligent collaborative scheduling of all elements among photovoltaic power generation, energy storage units, inverters, grid connections and loads, so as to maximize the benefit-cost ratio of the entire system.

[0034] In addition, the system adopts a modular and highly scalable design concept, enabling it to flexibly adjust its scale according to the demands of different markets and quickly adapt to the rapidly changing demands. Compared with the industry benchmark solutions, the system implemented based on this method is expected to increase the benefit-cost ratio by more than 30%. This significant improvement mainly comes from three aspects: First, the application of dynamic reconfiguration technology reduces the operation and maintenance costs by at least 15% throughout the entire life cycle, extends the system service life, and reduces the long-term maintenance costs; Second, the all-factor intelligent collaborative scheduling mechanism brings an additional operation efficiency gain of more than 10%, while providing additional values such as avoiding power curtailment, arbitraging the peak-valley electricity price difference, and providing grid value-added services; Finally, by reducing the number of dedicated converters, the hardware investment cost is further saved by more than 15%.

[0035] The dynamic reconfiguration technology relies on the real-time status monitoring of each battery sub-string, including voltage, current, temperature, and SOC (State of Charge). Among them, voltage: Monitor the voltage of each battery sub-string to identify the sub-strings with too high or too low voltage. Current: Monitor the charge and discharge current to ensure uniform current distribution. Temperature: Monitor the battery temperature to prevent performance degradation or safety hazards caused by overheating or overcooling. SOC: Evaluate the remaining power of each battery sub-string to ensure the SOC balance of each sub-string.

[0036] These data are collected in real time through sensors and the battery management system (BMS), providing the basis for dynamic reconfiguration.

[0037] The core objectives of the dynamic reconfiguration technology include avoiding reverse charging, controlling the voltage difference, and optimizing the performance. Avoiding reverse charging: Prevent the low-voltage sub-strings from being reversely charged by disconnecting them. Controlling the voltage difference: Control the voltage difference between each sub-string within a reasonable range through balance management and dynamic adjustment. Optimizing the performance: Improve the energy utilization efficiency of the battery pack and extend the battery life.

[0038] The principle of the dynamic reconfiguration technology is to dynamically adjust the connection mode of the battery sub-strings through real-time monitoring of the battery pack status, using a switch matrix and a balance circuit to achieve voltage balance, avoid reverse charging, and optimize the overall performance of the battery pack. Its core lies in real-time and dynamics, which can quickly make adjustments according to the changes in the battery pack status to ensure the safe, stable, and efficient operation of the battery pack.

[0039] In terms of safety, the highest standards are followed from individual components to the overall system, ensuring intrinsic safety. Specific measures include millisecond-level fault detection capabilities and microsecond-level isolation response times, as well as component-level energy balance management, effectively preventing problems such as overloading and overheating of photovoltaic components, overcharging and over-discharging of energy storage devices, and overloading or abnormal electrical parameters of inverters.

[0040] Refer toFigure 5 and Figure 6 , an embodiment of the present invention provides a photovoltaic-storage integrated system based on dynamic reconfigurable technology, including a photovoltaic-storage component, a digital energy network card, and a digital energy exchange system.

[0041] The digital energy network card is a high-speed control and data acquisition device for energy units. It is directly fixed on the battery module or battery rack using a customized copper bar and has a charge and discharge drive switch for the battery module.

[0042] The digital energy exchange system is an integrated control unit for the overall energy scheduling, advanced strategy execution, and communication management of the DESS system. It is used to collect the working states of each circuit, analyze, judge, and execute corresponding system management strategies; upload necessary data information of each part of the system; coordinate and schedule associated systems (such as PCS); and execute corresponding actions according to the system state and superior scheduling instructions.

[0043] The following will separately elaborate on the above contents:

[0044] A plurality of the photovoltaic-storage components form a photovoltaic-storage array of m×n×k, where m is the number of strings, n is the number of series-connected photovoltaic components in one string, and k is the number of parallel branches in each string; each of the photovoltaic-storage components includes a photovoltaic component and a energy storage component, the photovoltaic component and the energy storage component are connected in parallel, the photovoltaic component is used to supply power to the energy storage component, and whether each photovoltaic component and energy storage component is cut into the circuit is controlled by a power electronic switch;

[0045] The digital energy exchange system is used to formulate and issue the dynamic reconfigurable strategy of the photovoltaic-storage array; among them, the dynamic reconfigurable strategy includes the switching control of four states (i.e., the switching of four states of the photovoltaic-storage array) and the reconfigurable strategy for controlling the number of battery cells cut into the circuit, that is, dynamically switching between the mode of B battery cells, the mode of B+1 battery cells, and the mode of B+2 battery cells;

[0046] The digital energy network card communicates with the digital energy exchange system through an information bus, and real-time uploads the state information of the photovoltaic-storage components, and receives and executes the strategy of the digital energy exchange system. The digital energy exchange system and the digital energy network card cooperate with the photovoltaic-storage components, batteries, power electronic switches, and inverters to intelligently balance the energy distribution.

[0047] The present invention can achieve a component-level fine-grained control mode, supporting collaborative control between each photovoltaic component and energy storage component; the digital energy exchange system is used to detect the voltages of photovoltaic components and battery sub-strings in real time, and the dynamic reconfiguration technology is used to avoid reverse charging of battery sub-strings and control the voltage difference range. The system status is synchronized in real time at the microsecond level to achieve synchronous operation between components and reduce the transient effects caused by the dynamic access and disconnection of components from the circuit; the dynamic reconfiguration technology is used to achieve the full-element intelligent collaborative scheduling of all elements such as photovoltaic, energy storage, inverter, power grid, load, and power generation prediction model, maximizing the benefit-cost ratio of the entire system.

[0048] In view of the technical challenges encountered in photovoltaic power generation, the solutions proposed in the embodiments of the present invention are as follows:

[0049] (1) Implement a component-level fine-grained control mode: Support collaborative control between each photovoltaic and energy storage component and battery sub-string. Each photovoltaic and energy storage component is connected in parallel with a battery sub-string, and the battery sub-string includes B + 2 series-connected battery cells. The battery topology can be dynamically reconfigured in the series direction, and the number of battery cells connected to the access circuit can be B, B + 1, or B + 2. In the mode of B + 1 battery cells or B battery cells, the photovoltaic component can charge the battery sub-string. In the mode of B + 2 battery cells or B + 1 battery cells, the battery sub-string can replace the shaded or faulty photovoltaic for discharging. Among them, B battery cells in the circuit are always fixedly connected in series. According to different voltage modes, the number of battery cells connected to the access circuit is determined to be B, or B + 1, or B + 2 through an optimization algorithm. Such a design method can reduce the number of switches.

[0050] (2) There is no circulating current or it is controlled within an acceptable range between photovoltaic component strings: The digital energy exchange system is used to detect the voltages of photovoltaic components and battery sub-strings (energy storage components) in real time, and the dynamic reconfiguration technology is used to avoid reverse charging of battery sub-strings and control the voltage difference range. The system status is synchronized in real time at the microsecond level. For example, high-speed real-time communication protocols such as EtherCAT (Ethernet for Control Automation Technology, an open architecture, Ethernet-based fieldbus system, where the CAT in its name is the abbreviation of Control Automation Technology. EtherCAT is a deterministic industrial Ethernet) are used to achieve synchronous operation between components and reduce the transient effects caused by the dynamic access and disconnection of components from the circuit.

[0051] (3) Photovoltaic modules and battery sub-strings do not experience overcurrent: The digital energy exchange system continuously monitors the voltages of photovoltaic modules and battery sub-strings. Through dynamic reconfiguration technology, reverse charging of battery sub-strings is avoided, and the differential pressure range is controlled. Excessive differential pressure can affect the performance and lifespan of battery modules. Among them, the state of the photovoltaic modules and energy storage modules being switched into the circuit is dynamically controlled through dynamic reconfiguration technology, and the number of battery sub-strings switched into the circuit is controlled (dynamically configured in modes B, B+1, B+2). The optimization algorithm described later (i.e., solving the optimization problem with Equation (16) as the optimization objective, and the constraint conditions of this optimization problem are various combined constraint conditions formed by Equations (1) to (15) according to the requirements of different working modes) can determine the state and mode in real-time, thereby controlling the differential pressure range.

[0052] (4) The converter does not overload: The digital energy exchange system determines the operating states of each photovoltaic and energy storage component based on the real-time output power of the photovoltaic and energy storage systems, and always ensures that the total output power of the photovoltaic and energy storage array does not exceed the rated maximum power of the converter.

[0053] (5) High-precision detection: Based on dynamic reconfiguration technology, electrical measurement fault detection capabilities at the millisecond level and isolation functions at the microsecond level are achieved.

[0054] Furthermore, the energy storage component is a battery sub-string, and the battery sub-string includes B+2 serially connected battery cells. In the series direction, the number of battery cells connected to the circuit can be any one of B, B+1, and B+2.

[0055] Furthermore, the status information of the photovoltaic and energy storage components includes four types. The first type is that the photovoltaic module is online and the energy storage module is offline; the second type is that the photovoltaic module is online and the energy storage module is online for charging; the third type is that the photovoltaic module is offline and the energy storage module is online; the fourth type is that the photovoltaic module is offline and the energy storage module is offline.

[0056] Specifically, when the photovoltaic and energy storage components are in the state where the photovoltaic module is online and the energy storage module is offline, if both the photovoltaic module and the energy storage module are in normal states (the photovoltaic module is generating electricity normally and the SOC of the energy storage module is greater than or equal to 90%, in a fully charged state), then at this time, the photovoltaic module is in the power generation state and the energy storage module is in the fully charged state, that is, the SOC (State of Charge) value is greater than or equal to the given threshold, such as 90%.

[0057] When the digital energy exchange system detects that the photovoltaic module in a certain photovoltaic and energy storage component is in a shaded condition, with insufficient output current and reduced output power, affecting the power generation power of the entire string, and at the same time, the energy storage component connected in parallel with the photovoltaic module is fully charged and offline, then the digital energy exchange system switches the energy storage component into the circuit and switches the photovoltaic module out of the circuit, increasing the output current of the entire photovoltaic and energy storage component and maintaining the power generation power of the entire photovoltaic and energy storage component in balance with other photovoltaic modules on the string.

[0058] Specifically, when an obstacle blocks the photovoltaic module, the digital energy exchange system can make a judgment through specific algorithms. For example, by comparing information such as the voltage and current of each photovoltaic module in the same branch, an abnormal module with a large difference in voltage, current, and other components from other modules is selected, and the change trend is analyzed by combining the historical data of the abnormal module, so as to determine that there is an obstacle occlusion. These are all mature algorithms and not the invention content of this patent. Therefore, the algorithms here are not specifically described in this patent.

[0059] When the photovoltaic-storage module is in the state where the photovoltaic module is offline and the energy storage module is discharging online, taking the lithium iron phosphate battery as an example, since the lithium iron phosphate battery has a long plateau period during the discharging process, the voltage change range during the discharging process is limited, and as long as the current in the string does not exceed the maximum discharging current specification of the lithium iron phosphate battery (for example, for a lithium iron phosphate battery with a capacity of 314 Ah and a rate of 0.5C, the maximum discharging current specification can be set to 157 A), it can supply power safely for a long time. The discharging current depends on the minimum output current of other photovoltaic-storage modules in the string. When the energy storage module discharges to the cut-off voltage and there is a demand for output power, the digital energy exchange system cuts the energy storage module out of the circuit and cuts the photovoltaic module into the circuit. Among them, the photovoltaic module being offline does not mean that the photovoltaic module will not be connected to the circuit later. When the photovoltaic module is online, whether there is a fault can be detected by conventional fault detection methods, and the detection methods are not within the scope of this patent. In the offline state, it is assumed that the photovoltaic module is normal, and whether there is a fault is detected again after it is cut into the circuit.

[0060] When the photovoltaic-storage module is in the state where the photovoltaic is online and the energy storage is offline, the digital energy exchange system detects that the energy storage module has insufficient capacity and needs to be charged, and at the same time the power generation power of the photovoltaic module is greater than the rated power generation power, then the energy storage module is cut into the circuit. At this time, the voltage of the battery cells cut into the circuit needs to be less than the output voltage of the photovoltaic module. First, B + 2 battery cells are connected to the circuit. When the voltage of the energy storage module is close to the voltage of the photovoltaic module, the mode of B + 1 battery cells is switched, and the charging continues; when the voltage of the energy storage module in the mode of B + 1 battery cells is close to the voltage of the photovoltaic module, the mode of B battery cells connected to the circuit is switched. Among them, the voltage of the battery cell that has been cut out is already large enough, so there is no need to charge this battery cell until it is cut into the circuit for discharging next time. Through an optimized algorithm, it is possible to control when the battery cells are cut into and out of the circuit as needed.

[0061] When the photovoltaic-storage module is in the state where the photovoltaic module is online and the energy storage module is charging online, after the digital energy exchange system detects that the voltage of B + 2 battery cells reaches the charging cut-off voltage (taking the lithium iron phosphate battery as an example, it can be configured as 3.55 V), the energy storage module is cut out of the circuit, and it enters the state where the photovoltaic module is online and the energy storage module is offline.

[0062] In the event of a severe fault (such as overheating, insulation failure, etc.) occurring in any normal state, the digital energy exchange system will disconnect the photovoltaic and energy storage components from the circuit and enter a state where the photovoltaic components are offline and the energy storage components are offline.

[0063] In the mode of B + 1 battery cells or B battery cells, the photovoltaic components charge the battery sub-strings; in the mode of B + 2 battery cells or B + 1 battery cells, the battery sub-strings replace the shaded or faulty photovoltaic components.

[0064] Furthermore, the voltage of the energy storage component is less than that of the photovoltaic component. Specifically, when the battery voltage is higher than the photovoltaic component voltage, it will have an adverse impact on the photovoltaic system, including reverse current flow, system performance degradation, equipment protection, and energy management. Therefore, when configuring the system and balancing the digital energy system, generally, the situation where the battery voltage is higher than the photovoltaic component voltage should be avoided except for special requirements. The digital energy exchange system can be an energy switch, which is used to detect the voltages of the photovoltaic and energy storage components in real time, avoid reverse charging of the energy storage component through dynamic reconstruction technology, and control the voltage difference range.

[0065] Typical system configuration parameters are shown in Tables 1 to 3 below:

[0066] Table 1 Typical Parameters of 48V Photovoltaic Components

[0067] Parameter Typical value Rated output voltage (V) 48 Maximum power point voltage (W) 40～55 Open - circuit voltage (V) 55～65 Short - circuit current (A) 5～10 Maximum power point current (A) Slightly less than short - circuit current Maximum output power (W) 550 Temperature coefficient For every 1°C rise, open - circuit voltage drops by 0.3 - 0.5% Efficiency 15～22％ Operating temperature range (°C) -40～85℃ Protection grade IP65

[0068] Table 2 Typical Parameters of Digital Energy Network Cards

[0069] Parameter Typical value Maximum voltage (V) 85 Maximum current (A) 300 Maximum voltage of energy bus (V) 1250 Maximum current of energy bus (A) 1100

[0070] Table 3 Specification Parameters of Lithium Iron Phosphate Battery Cells

[0071] Parameter Typical value Charge cut - off voltage (V) 3.55 Discharge cut - off current (V) 2.9 Maximum current @0.5C / 20Ah (A) 10 Rated power (W) 32

[0072] The optimization algorithm is as follows:

[0073] Assume that the open-circuit voltage of the photovoltaic component in the i-th row and j-th column at time t is VP i,j (t), the working voltage is and the working current is The open-circuit voltages of the current energy storage components (B + 2, B + 1, B) are VB2 i,j (t), VB1 i,j (t), VB i,j (t) respectively, and the state of the photovoltaic component connected to the circuit is SP i,j (t). The states of the current energy storage components (B, the first cell, the second cell) connected to the circuit are SB i,j (t), SB1 i,j (t), SB2i,j (t), the state value of the access circuit being 0 indicates non - access to the circuit, and 1 indicates access to the circuit. Assume the scale of the photovoltaic - energy storage array is I rows and J columns, with the PCS connected in the row direction. The topological structure at any moment needs to satisfy the constraint that the voltage difference of any row is less than the given threshold value δ V That is:

[0074]

[0075] i 1 ≠i 2 , i 1 , i 2 ∈{1, 2,..., I} (2)

[0076] In the above formula, i 1 and i 2 represent the numbers of any two different rows among the rows numbered 1 to I in the photovoltaic - energy storage array, and j represents the number of any column among the columns numbered 1 to J in the photovoltaic - energy storage array.

[0077] Since at the same moment, for the same photovoltaic - energy storage component, there are cases where the photovoltaic component, the current energy - storage component either accesses the circuit, or both access the circuit simultaneously, or both cut out of the circuit simultaneously. There are the following constraint conditions for the component access to the circuit:

[0078] SP i,j (t)+SB2 i,j (t)+SB1 i,j (t)+SB i,j (t)∈{0, 1, 2} i∈{1, 2,..., I}, j∈{1, 2,..., J} (3)

[0079] SB2 i,j (t)+SB1 i,j (t)+SB i,j (t)∈{0, 1} i∈{1, 2,..., I}, j∈{1, 2,..., J} (4)

[0080] When the photovoltaic component charges the energy - storage component, it is necessary to satisfy that the voltage of the photovoltaic component is greater than that of the energy - storage component, and one of the following three conditions holds:

[0081]

[0082] In the above formula, δ C represents the voltage - difference threshold value, such as 1V.

[0083] When the photovoltaic component charges the energy - storage component, the power generation power of the photovoltaic component in the recent period needs to satisfy being greater than the given power - generation power threshold P C before it can charge the energy - storage component. Let the cycle time be T, and the default setting is 10 seconds, then there is:

[0084]

[0085] When the energy storage component is being charged by the photovoltaic module, when the open-circuit voltage of the energy storage component reaches the charging cut-off voltage, the energy storage component is disconnected from the circuit, that is:

[0086]

[0087] In the above formula, VB C,max , VB1 C,nax , VB2 C,max is the charging cut-off voltage of the energy storage component, which is defined as the number of series-connected battery cells of the energy storage component multiplied by the single-cell charging cut-off voltage. Taking lithium iron phosphate batteries as an example, the single-cell charging cut-off voltage can be defined as 3.55V.

[0088] When the energy storage component is being charged by the photovoltaic module, when the power generation power of the photovoltaic module in a recent period is less than a certain percentage of the given power generation power threshold P C , and this proportional quantity is α, with a default value of 0.8, the energy storage component is disconnected from the circuit, that is:

[0089]

[0090] When the energy storage component satisfies that the open-circuit voltage is greater than the discharge cut-off voltage, it is allowed to be connected to the circuit to replace the corresponding photovoltaic module for power generation, that is:

[0091]

[0092]

[0093] In the above formula, VB D,min , VB1 D,min , VB2 D,min is the discharge cut-off voltage of the energy storage component, which is defined as the number of series-connected battery cells of the energy storage component multiplied by the single-cell discharge cut-off voltage. Taking lithium iron phosphate batteries as an example, the single-cell discharge cut-off voltage can be defined as 2.9V.

[0094] Under the constraint conditions of satisfying the above various states, the basic optimization goal of the photovoltaic and energy storage component configuration of the entire system is to maximize the power generation power, with the maximum available open-circuit voltage sum as the optimization goal, or other optimization goals formed according to specific scenario requirements. The optimization goal of the maximum open-circuit voltage sum is:

[0095]

[0096] Taking the formula (16) as the optimization objective and the combined constraint conditions formed by the formulas (1) to (15) according to the requirements of different modes constitute an optimization problem. By solving this optimization problem, the states of the photovoltaic module and the energy storage module connected to the circuit and the working modes are determined. That is, the optimization objective of the formula (16) is SB, SB1, SB2, SP. After these values are determined, the states of the photovoltaic module and the energy storage module connected to the circuit and the working modes can be determined.

[0097] After adding the constraint conditions of the pressure difference of the parallel branch, the switch state of the photovoltaic and energy storage modules connected to the circuit, the charging of the photovoltaic module to the energy storage module, and the discharging of the energy storage module according to this optimization objective, the resource scheduling optimization models under various state conditions can be obtained. The mathematical problems of these optimization models are transformed into integer linear programming problems for solution.

[0098] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. The photovoltaic storage integrated system based on dynamic reconfigurable technology is characterized by: It includes a photoelectric storage component, a digital energy network card and a digital energy exchange system; A plurality of the photovoltaic storage components constitute an m×n×k photovoltaic storage array, wherein m is the number of strings, n is the number of photovoltaic components connected in series in a string, and k is the number of branches connected in parallel in each string; each photovoltaic storage component comprises a photovoltaic component and an energy storage component, the photovoltaic component and the energy storage component are connected in parallel, and the photovoltaic component is used to supply power to the energy storage component; The digital energy exchange system is used to formulate and download a dynamic reconfigurable strategy for the light storage array; The digital energy network card communicates with the digital energy exchange system via the information bus, uploads the status information of the optical storage component in real time, and receives and executes the strategy of the digital energy exchange system.

2. The photovoltaic storage integrated system based on dynamic reconfigurable technology according to claim 1 is characterized in that: The status information of the photovoltaic storage component includes four types. The first type is that the photovoltaic component is online and the energy storage component is offline; the second type is that the photovoltaic component is online and the energy storage component is charged online; the third type is that the photovoltaic component is offline and the energy storage component is online; the fourth type is that the photovoltaic component is offline and the energy storage component is offline.

3. The photovoltaic storage integrated system based on dynamic reconfigurable technology according to claim 1 is characterized in that: Each of the photovoltaic components and energy storage components is controlled by a power electronic switch to be connected to the circuit.

4. The photovoltaic storage integrated system based on dynamic reconfigurable technology according to any one of claims 1 to 3, characterized in that: The energy storage component is a battery substring, and the battery substring includes B+2 ​​battery cells connected in series, where B is defined as the minimum number of battery cells that are simultaneously switched into the loop in the battery substring.

5. The photovoltaic storage integrated system based on dynamic reconfigurable technology according to claim 2 is characterized in that: In the series connection direction, the number of battery cells connected to the loop is any one of B, B+1, and B+2.

6. The photovoltaic storage integrated system based on dynamic reconfigurable technology according to claim 5 is characterized in that: When the photovoltaic storage component is in the first state, that is, the photovoltaic component is online and the energy storage component is offline, the digital energy exchange system detects that the energy storage capacity is less than the preset energy storage value and needs to be charged. At the same time, the photovoltaic component power generation power is greater than the rated power generation power, then the energy storage component is cut into the loop. At this time, the voltage of the battery cell cut into the loop needs to be less than the output voltage of the photovoltaic component.

7. The photovoltaic storage integrated system based on dynamic reconfigurable technology according to claim 5 is characterized in that: When the photovoltaic storage component is in the second state, that is, the photovoltaic component is online and the energy storage component is online charging, the digital energy exchange system detects that the voltage of B+2 battery cells reaches the charging cut-off voltage, then cuts the energy storage component out of the loop and enters the first state, that is, the photovoltaic component is online and the energy storage component is offline.

8. The photovoltaic storage integrated system based on dynamic reconfigurable technology according to claim 1 is characterized in that: In the mode of B+1 battery cells or B battery cells, the photovoltaic modules charge the battery substrings; in the mode of B+2 battery cells or B+1 battery cells, the battery substrings replace the blocked or faulty photovoltaic modules.

9. The photovoltaic storage integrated system based on dynamic reconfigurable technology according to claim 1 is characterized in that: The voltage of the energy storage component is lower than the voltage of the photovoltaic component.

10. The photovoltaic storage integrated system based on dynamic reconfigurable technology according to claim 1 is characterized in that: The digital energy exchange system detects the voltage of the photovoltaic component and the energy storage component in real time, avoids reverse charging of the energy storage component through dynamic reconstruction technology, and controls the voltage difference range.

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