Photovoltaic energy storage cooperative power generation system and method

Abstract

The invention relates to the technical field of photovoltaic power generation, and discloses a photovoltaic energy storage cooperative power generation system and method.The photovoltaic energy storage cooperative power generation system comprises a photovoltaic assembly, an intelligent string structure, an energy storage system and an intelligent controller, and the photovoltaic assembly comprises an east assembly and a west assembly and is connected to the direct current end of the same inverter to balance the morning and evening power generation peak values. The group string structure adopts a fixed group string and a switchable group string to be connected in parallel, and the group strings are dynamically switched to be connected and disconnected through an intelligent switch to adapt to irradiation fluctuation. The energy storage system comprises an energy storage battery and a bidirectional converter, a direct current end is connected with the battery, an alternating current end is connected with a grid through an intelligent switch, and charging and discharging scheduling under a peak-valley electricity price strategy is supported. The intelligent controller integrates a power prediction module, an economic dispatching module and an equipment protection module, monitors photovoltaic output, an energy storage SOC and a power grid state in real time, and dynamically optimizes string switching, energy storage charging and discharging and inverter operation parameters. Through east-west assembly power balance, flexible string reconstruction and energy storage intelligent scheduling, power generation income maximization and equipment service life prolonging are realized.

Description

Technical Field

[0001] The present invention belongs to the field of photovoltaic power generation technology, and specifically relates to the optimization of component layout, power management, energy storage coordination, and intelligent control in photovoltaic power generation systems. Background Art

[0002] With the growing global demand for clean energy and increasing pressure to address climate change, photovoltaic power generation, as a sustainable, pollution-free, clean energy source, has experienced rapid development in recent years. From early small-scale experimental projects to the widespread deployment of large-scale photovoltaic power plants and distributed photovoltaic power generation systems, photovoltaic power generation has gradually increased its share in the global energy mix. Government policy support, technological advancements, and declining costs are driving the photovoltaic power generation industry towards greater efficiency, cost-effectiveness, and reliability.

[0003] Current State of the Art: First, in existing photovoltaic power generation systems, PV panels are mostly arranged in a single orientation, typically facing due south, to maximize sunlight. This layout achieves high power generation efficiency under ideal sunlight conditions. However, in actual operation, due to the sun's constantly changing position throughout the day, particularly in the morning and evening when the sun's angle is lower, the sunlight intensity received by single-oriented PV panels is relatively weak, resulting in lower power generation efficiency during these periods, thus affecting the total daily power generation. Second, the current configuration of inverters and strings is relatively fixed. Most systems use a fixed capacity ratio, that is, the ratio of the total DC power of the inverter to the rated AC output power. This fixed capacity ratio cannot adapt well to changes in light intensity and power generation. Under high light intensity, it may cause inverter overload, affecting its service life and power generation efficiency. Under low light intensity, it may not fully utilize the power generation capacity of the PV panels, resulting in power waste. Furthermore, the connection method between the strings and the inverter is usually fixed, lacking the ability to dynamically adjust according to actual power generation conditions. Third, while the application of energy storage systems in photovoltaic power generation is increasing, the coordination between energy storage and photovoltaic systems still presents numerous challenges. The charge and discharge control of energy storage systems is often simplistic, failing to fully consider factors such as the inverter output power, the generated power of the photovoltaic modules, and the grid's needs. For example, when the inverter output power is too high, the energy storage system may not be able to absorb and store excess energy in a timely and effective manner. Furthermore, when the grid needs additional power (such as during peak electricity price periods or when photovoltaic power generation is insufficient), the energy storage system may not be able to discharge power to the grid in a timely manner, resulting in the energy storage system's full benefits being unrealized and affecting the stability and economic efficiency of the entire photovoltaic power generation system. Fourth, the intelligence level of existing photovoltaic power generation system control systems is limited; many systems cannot effectively integrate meteorological data, historical power generation data, and grid-related information (such as electricity price signals) to comprehensively control and optimize the system. For example, the inability to accurately predict photovoltaic output means that system operating parameters, such as the connection status of the string and the charge and discharge of the energy storage system, cannot be adjusted in a timely manner in response to weather changes, thus affecting power generation efficiency and the system's economic benefits. Summary of the Invention

[0004] In view of this, the present invention proposes an optimization method and system for a photovoltaic power generation system, aiming to solve the problems of poor technical synergy and low processing efficiency in current technologies.

[0005] The present invention provides a photovoltaic energy storage collaborative power generation system, comprising: a photovoltaic module, which includes an east-facing module and a west-facing module, the east-facing module and the west-facing module are connected to the DC input terminal of the same inverter, and the power ratio thereof is between 45% and 55%; a string connection structure, which includes a fixed string and a switchable string, the fixed string and the switchable string are connected in parallel and connected to the DC input terminal of the inverter, the power ratio of the fixed string to the switchable string is between 30% and 70%, and the access line of the fixed string is a permanent closed loop; an intelligent switch for controlling the The switchable strings can be turned on and off, as well as the connection between the energy storage converter and the power grid; the energy storage system includes an energy storage battery and an energy storage converter, the DC end of the energy storage battery is connected to the DC end of the energy storage converter, and the AC end of the energy storage converter is connected to the power grid through the intelligent switch; the intelligent controller is communicatively connected to the energy storage system and includes a power prediction module, an economic dispatch module and an equipment protection module; the intelligent controller monitors the working status of the photovoltaic components, energy storage system and inverter in real time through the communication connection, and adjusts system parameters according to the monitoring data to optimize power generation efficiency.

[0006] Furthermore, the capacity ratio is controlled within the range of 1.5-3 by dynamically adjusting the access ratio of the switchable strings.

[0007] Furthermore, the installation directions of the east-facing components and the west-facing components are respectively facing due east and due west to maximize the light utilization rate during sunrise and sunset.

[0008] Furthermore, the energy storage converter is a bidirectional DC / AC converter, whose DC side is directly connected to the DC bus of the energy storage battery, and the AC side is connected in parallel to the AC output end of the inverter through an intelligent switch, and its DC side input voltage range covers the rated voltage of the energy storage battery.

[0009] Furthermore, the switchable strings adopt a modular design, each module contains 2-5 series components and is equipped with an independent DC / DC converter to achieve maximum power point tracking (MPPT).

[0010] Furthermore, the power prediction module in the intelligent controller receives real-time meteorological data and historical power generation data, predicts future photovoltaic power generation, and constructs a photovoltaic power generation prediction formula based on the real-time meteorological data and historical power generation data. The photovoltaic power generation prediction formula is:

[0011]

[0012] Among them, G (t) is the real-time irradiance (W / m 2 );T (t) is the photovoltaic panel temperature (℃); T refis the standard test temperature; β is the temperature power attenuation coefficient, typically 0.3-0.5%; η is the overall efficiency, usually 15%-25%; A is the effective area of the photovoltaic array (m 2 );P hist,avg (t during the same period) is the average power generation during the same period in history; P hist,base It is the historical benchmark power generation, used to eliminate the impact of changes in installed capacity.

[0013] Furthermore, the economic dispatch module is used to determine the charging and discharging strategy of the energy storage system based on electricity prices, load demand and energy storage status; the charging and discharging strategy includes: based on the high and low periods of electricity prices, the size of load demand, and the remaining power and health status of the energy storage status, the charging and discharging power and time of the energy storage system are determined by a preset algorithm or model; the preset algorithm or model includes: when the electricity price is in a low price period and the energy storage status has not reached full power, the charging power is determined according to the predicted value of the load demand to maximize the charging amount while meeting the load demand; when the electricity price is in a high price period and the energy storage status has dischargeable power, the discharge power is determined according to the predicted value of the load demand to reduce the purchase of electricity from the power grid while meeting the load demand; the economic dispatch method also includes adjusting the charging and discharging strategy according to the health status of the energy storage status, and when the health status of the energy storage system is not good, the charging and discharging power is reduced to protect the energy storage system.

[0014] Furthermore, the device protection module is used to monitor the working status of photovoltaic components, energy storage systems and inverters, and execute protection strategies when an abnormality occurs; the device protection module includes a monitoring unit for monitoring the working status of photovoltaic components, energy storage systems and inverters, and an execution unit for executing protection strategies when an abnormality is detected in the working status of the photovoltaic components, energy storage systems or inverters; the monitoring unit includes sensors connected to the photovoltaic components, energy storage systems and inverters respectively, the sensors are used to obtain parameters representing the working status, and the execution unit determines whether an abnormality occurs based on the parameters obtained by the sensors; the sensors include but are not limited to temperature sensors. Sensor, voltage sensor, current sensor, the execution unit determines whether an abnormality occurs based on the comparison of parameters such as temperature, voltage, current and preset thresholds; the protection strategy includes a power adjustment strategy for photovoltaic component abnormalities, a charge and discharge control strategy for energy storage system abnormalities and a circuit switching strategy for inverter abnormalities; when the execution unit determines that the temperature of the photovoltaic component exceeds the preset temperature range, it executes the protection strategy by reducing its operating power; when the energy storage system voltage exceeds the preset voltage range, it adjusts its charge and discharge state to execute the protection strategy; when the inverter current exceeds the preset current range, it switches the circuit to execute the protection strategy.

[0015] The present invention also provides a photovoltaic energy storage collaborative power generation method, comprising the following steps:

[0016] (a) Arrange the photovoltaic array in a predetermined ratio facing east and west, so that the power of the east-facing modules and the west-facing modules connected to the same inverter are equal or the difference is less than 10%;

[0017] (b) configuring fixed strings and switchable strings to be connected in parallel to the inverter, wherein the power ratio of the fixed strings to the switchable strings is 30%-70%;

[0018] (c) Real-time monitoring of the inverter output power through an intelligent controller;

[0019] (d) When the output power of the inverter reaches 90%-95% of its rated value, the switchable strings are switched from the inverter to the energy storage battery for direct charging via the intelligent switch;

[0020] (e) When the output power of the inverter is lower than 85% of its rated value or during the peak electricity price period, the energy storage battery is switched to discharge to the grid through the energy storage converter;

[0021] (f) Maintain the system's capacity ratio at 1.5-3, where the capacity ratio is defined as the ratio of the total DC-side power of the inverter to the rated AC-side output power.

[0022] Furthermore, steps (d) and (e) further include: (d1) when the inverter output power reaches 90%-95% of the rated value, gradually switching to the energy storage battery in increments of no more than 10% of the total switchable string capacity each time; (e1) when the inverter output power is lower than 85% of the rated value, gradually switching back to the inverter in increments of no more than 10% of the total capacity of the energy storage battery each time.

[0023] Beneficial effects:

[0024] First, the east-west layout of the PV panels and their rational power allocation allow for full utilization of sunlight during sunrise and sunset, reducing periods of low power generation, improving all-day power generation efficiency, reducing the unit investment in the PV system, and significantly increasing investment returns. Dynamic adjustment of the string connection structure optimizes the capacity allocation, enabling the inverter to operate at a more efficient state, reducing losses during power conversion, and further improving power generation efficiency. The switchable string design provides flexibility in the string connection structure, enabling dynamic adjustment based on actual power generation conditions to accommodate varying lighting conditions and load demands. The DC input voltage range of the energy storage inverter covers the rated voltage of the energy storage battery, enabling the energy storage system to adapt to different energy storage battery states and improving the adaptability of the entire power generation system to different operating conditions.

[0025] Second, the intelligent controller's economic dispatch module comprehensively considers electricity prices, load demand, and energy storage status to develop a more reasonable charging and discharging strategy. Fully charging during low-price periods and discharging appropriately during high-price periods not only improves the efficiency of the energy storage system but also reduces power generation costs. Adjusting the charging and discharging strategy based on the health of the energy storage system can extend the system's service life and improve its overall performance and reliability. The intelligent controller's power prediction module, through precise power forecasting, provides an accurate basis for power generation system scheduling, helping to proactively address power fluctuations and improve power generation system stability. The equipment protection module, through comprehensive monitoring and comprehensive protection strategies, promptly detects and addresses equipment anomalies, effectively preventing equipment damage and power generation system failures, thereby improving power generation system reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of energy storage connection of the present invention;

[0027] Figure 2 This is a schematic diagram of the arrangement of photovoltaic modules of the present invention;

[0028] Figure 3 Arrange schematic diagrams for prior art components;

[0029] Figure 4 This is a schematic diagram of energy storage connection in the prior art;

[0030] Figure 5 This is a power generation curve diagram facing due south (existing technology);

[0031] Figure 6 This is the power generation curve diagram facing due east;

[0032] Figure 7 This is the power generation curve diagram facing due west;

[0033] Figure 8 The figure is a comparison diagram of the power generation curves of the prior art and the present invention.

[0034] In the figure: photovoltaic inverter 1, energy storage converter 2, intelligent controller 3, energy storage battery 4, intelligent control switch 5, switchable string 6, fixed string 7, east-facing module 8, west-facing module 9. DETAILED DESCRIPTION

[0035] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0036] like Figures 1 to 8As shown, the following embodiments are provided;

[0037] Example 1:

[0038] A photovoltaic power generation optimization method based on east-west power balancing was developed. Background: Existing photovoltaic systems generally use a single-orientation layout for their components, resulting in inverter power imbalances during the morning and evening hours, reducing conversion efficiency. Furthermore, high-capacity systems often curtail power due to inverter capacity limitations, and energy storage systems have a limited scheduling strategy, making it difficult to account for fluctuations in grid electricity prices.

[0039] Step Description:

[0040] Component layout: Arrange the east-facing components 8 and west-facing components 9 of the photovoltaic array in a ratio of 45%-55%, and the power difference of the strings in each direction is less than 10%.

[0041] String configuration: Fixed strings 7 and switchable strings 6 are connected in parallel to inverter 1 at a power ratio of 30%-70%. The fixed string circuit is permanently closed, and the switchable strings are controlled by smart switches 5.

[0042] Power Monitoring: Intelligent controller 3 collects inverter output power in real time and combines it with grid electricity price signals. Dynamic Switching: When inverter power is ≥ 90% of rated power, switchable strings 6 are gradually switched to energy storage battery 4 for charging, in increments of ≤ 10% capacity. When power is < 85% or at peak electricity prices, the reverse direction is switched, with the energy storage battery discharging to the grid via converter 2.

[0043] Capacity ratio control: By adjusting the proportion of switchable strings connected, the DC side total power / AC side power ratio is maintained at 1.5-3.

[0044] Real-time monitoring of inverter power and electricity price signals:

[0045] If power ≥ threshold 1 → trigger energy storage charging mode;

[0046] If power ≤ threshold 2 or electricity price peak → trigger energy storage discharge mode;

[0047] Dynamically adjust the capacity ratio to match the generation / inversion capacity.

[0048] Example 2:

[0049] Implementation Background: Traditional photovoltaic system energy storage access methods are complex, easily causing current shocks during switching, and lack the ability to respond to electricity price signals.

[0050] Step Description:

[0051] Hardware configuration:

[0052] The east-facing PV array components 8 and west-facing PV array components 9 are connected in parallel via a DC combiner box. The fixed strings 7 and the switchable strings 6 are connected to the inverter 1 at a power ratio of 70:30.

[0053] The energy storage system includes an energy storage battery 4, a bidirectional DC / AC converter 2 and an intelligent switch 5. The DC side of the converter is directly connected to the battery, and the AC side is connected in parallel to the inverter output.

[0054] The intelligent controller 3 integrates power prediction, economic dispatch and equipment protection modules.

[0055] Operation mode:

[0056] Charging mode: When the inverter power exceeds the limit, the intelligent switch 5 switches the switchable string to the energy storage battery;

[0057] Discharge mode: During peak electricity price periods, the energy storage battery is inverted into AC power by converter 2 and fed into the grid.

[0058] Component connection instructions:

[0059] The photovoltaic array outputs DC power to the DC combiner box to complete current converging and protection.

[0060] DC combiner box → Inverter 1: After DC power is combined, it is converted into AC power through inverter 1 and integrated into the grid.

[0061] DC combiner box Smart Switch 5

[0062] Smart switch 5 serves as the core control node, enabling dynamic switching between two paths:

[0063] Path ① Forward: PV DC power flows directly to inverter 1 and is connected to the grid.

[0064] Path ② Bidirectional: The surplus photovoltaic power is stored in the energy storage battery 4 through the energy storage converter 2, or discharged from the energy storage battery and fed back to the DC bus.

[0065] Smart switch Energy storage converter 2

[0066] The energy storage converter 2 is a bidirectional DC / DC or DC / AC device with the following functions:

[0067] Charging mode: adjusts the DC power to a voltage / current suitable for the energy storage battery.

[0068] Discharge mode: Converts the DC power of the energy storage battery into a voltage that matches the DC bus.

[0069] Energy storage converter Energy storage battery 4

[0070] Realize battery charge and discharge management and be controlled by the economic dispatch module.

[0071] Example 3:

[0072] In this embodiment, the power prediction module in the intelligent controller receives real-time meteorological data and historical power generation data to predict future photovoltaic power generation. A photovoltaic power generation prediction formula is constructed based on the real-time meteorological data and historical power generation data. The photovoltaic power generation prediction formula is:

[0073]

[0074] Among them, G (t) is the real-time irradiance (W / m 2 );T (t) is the photovoltaic panel temperature (℃); T ref is the standard test temperature; β is the temperature power attenuation coefficient, typically 0.3-0.5%; η is the overall efficiency, usually 15%-25%; A is the effective area of the photovoltaic array (m 2 );P hist,avg (t during the same period) is the average power generation during the same period in history; P hist,base It is the historical benchmark power generation, used to eliminate the impact of changes in installed capacity.

[0075] Furthermore, the economic dispatch module is used to determine the charging and discharging strategy of the energy storage system based on electricity prices, load demand and energy storage status; the charging and discharging strategy includes: based on the high and low periods of electricity prices, the size of load demand, and the remaining power and health status of the energy storage status, the charging and discharging power and time of the energy storage system are determined through a preset algorithm or model; the preset algorithm or model includes: when the electricity price is in a low price period and the energy storage status has not reached full power, the charging power is determined according to the predicted value of the load demand to maximize the charging amount while meeting the load demand; when the electricity price is in a high price period and the energy storage status has dischargeable power, the discharge power is determined according to the predicted value of the load demand to meet the load demand while reducing the purchase of electricity from the power grid; the economic dispatch method also includes adjusting the charging and discharging strategy according to the health status of the energy storage status, and when the health status of the energy storage system is not good, the charging and discharging power is reduced to protect the energy storage system.

[0076] In this embodiment, the device protection module is used to monitor the operating status of the photovoltaic components, energy storage system, and inverter, and to execute a protection strategy when an abnormality occurs. The device protection module includes a monitoring unit for monitoring the operating status of the photovoltaic components, energy storage system, and inverter, and an execution unit for executing the protection strategy when an abnormality is detected in the operating status of the photovoltaic components, energy storage system, or inverter. The monitoring unit includes sensors connected to the photovoltaic components, energy storage system, and inverter, respectively, and the sensors are used to obtain parameters representing the operating status. The execution unit determines whether an abnormality has occurred based on the parameters obtained by the sensors. The sensors include but are not limited to temperature sensors, voltage sensors, and current sensors. The execution unit determines whether an abnormality has occurred based on a comparison of parameters such as temperature, voltage, and current with preset thresholds. The protection strategy includes a power adjustment strategy for photovoltaic component abnormalities, a charge and discharge control strategy for energy storage system abnormalities, and a circuit switching strategy for inverter abnormalities. When the execution unit determines that the temperature of the photovoltaic component exceeds a preset temperature range, it executes the protection strategy by reducing its operating power. When the voltage of the energy storage system exceeds a preset voltage range, it adjusts its charge and discharge state to execute the protection strategy. When the current of the inverter exceeds a preset current range, it switches the circuit to execute the protection strategy.

[0077] Example 4:

[0078] Due to the significant reduction in the cost of photovoltaic modules, the DC side cost of photovoltaic power generation modules has been reduced to less than 40% at this stage. The proportion of transmission, distribution and energy storage costs has risen to more than 60%, becoming the main cost. The unit investment of photovoltaic power stations is calculated based on different capacity ratios of the existing technology and the present invention:

[0079] (1) Calculation conditions: The existing technology has a capacity-to-power ratio of 1:1.15, while the present invention has a capacity-to-power ratio of between 1:2 and 1:3. Calculations are made based on two extreme cases: Currently, the cost of a single kilowatt photovoltaic module, i.e., the power generation part (including labor, brackets, modules, DC cables, etc.) is approximately RMB 1,000 / kW, while the cost of the transmission and distribution system is between RMB 1,000 and RMB 2,500 / kW. This cost includes inverters, junction boxes, AC cables and bridges, grid-connected cabinets, information management systems, transformers, and energy storage equipment (the cost of high-voltage transmission and distribution power and energy storage alone will not be less than RMB 2,000 / kW). For the sake of convenience, the average cost of RMB 1,800 / kW is used for calculation and compared with the construction of a 1,000kW photovoltaic power station.

[0080] (2) Unit cost of existing technology construction: 1000*1300=130,0000 yuan. The existing technology generally takes a capacity ratio of 1.15, so the required transmission and distribution power = 1000KW / 1.15=869.6KW. The cost per kilowatt of transmission and distribution (inverter, cable, switchgear, transformer, etc.) is 869.6*1800 yuan / KW=1565280 yuan. The system unit comprehensive cost = (1300000+1565280) / 1000=2862.6 yuan / KW

[0081] (3) Construction cost comparison of the present invention with a capacity ratio of 1:2: The cost of a 1000KW photovoltaic module remains unchanged at RMB 130,0000, and the power transmission and distribution equipment required for a 1000KW photovoltaic module is only

[0082] =1000 / 2=500KW, then the transmission and distribution price = 500KW*1800 yuan / kw=900000 yuan; the total investment of single kilowatt equipment = (130000+900000) / 1000=2200 yuan / KW.

[0083] (4) Comparison of construction costs of the present invention with a capacity ratio of 1:2: the cost of a 1000KW photovoltaic module remains unchanged at RMB 130,0000. The power transmission and distribution equipment required for a 1000KW photovoltaic module has a power of 1000 / 3 = 333KW, and the power transmission and distribution price = 333KW*1800 yuan / kw = 600000 yuan; the total investment per kilowatt equipment = (130000+600000) / 1000 = 1900 yuan / KW.

[0084] Investment cost savings: 1:2 capacity ratio = (2862.6 - 2200) / 2862.6 * 100% = 30%. If the capacity ratio is increased to 1:3, the cost reduction ratio between the present invention and the prior art = (2862.6 - 1900) / 2862.6 * 100% = 40.6%. With the revenue per watt remaining unchanged, the investment cost reduction is equivalent to the revenue increase, indicating that this technology can significantly improve the return on investment for photovoltaic power generation.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A photovoltaic energy storage coordinated power generation system, characterized in that: include: A photovoltaic module comprising an east-facing module and a west-facing module, wherein the east-facing module and the west-facing module are connected to the DC input of the same inverter, and the power ratio of the east-facing module and the west-facing module is between 45% and 55%. A string connection structure comprising a fixed string and a switchable string, wherein the fixed string and the switchable string are connected in parallel to the DC input of the inverter, the power ratio of the fixed string to the switchable string is between 30% and 70%, and the connection line of the fixed string is a permanent closed loop. An intelligent switch is used to control the on and off of the switchable strings and the connection between the energy storage converter and the power grid; the energy storage system includes an energy storage battery and an energy storage converter, the DC end of the energy storage battery is connected to the DC end of the energy storage converter, and the AC end of the energy storage converter is connected to the power grid through the intelligent switch; an intelligent controller is communicatively connected to the energy storage system and includes a power prediction module, an economic dispatch module, and an equipment protection module; the intelligent controller monitors the operating status of the photovoltaic modules, energy storage system, and inverter in real time through the communication connection, and adjusts system parameters based on the monitoring data to optimize power generation efficiency.

2. The system according to claim 1, wherein: The capacity ratio is controlled within the range of 1.5-3 by dynamically adjusting the access ratio of the switchable strings.

3. The system according to claim 2, characterized in that The installation directions of the east-facing components and the west-facing components are respectively facing due east and due west to maximize the light utilization rate during sunrise and sunset.

4. The system according to claim 3, characterized in that The energy storage converter is a bidirectional DC / AC converter, whose DC side is directly connected to the DC bus of the energy storage battery, and the AC side is connected in parallel to the AC output end of the inverter through an intelligent switch. The DC side input voltage range covers the rated voltage of the energy storage battery.

5. The system according to claim 4, characterized in that The switchable strings adopt a modular design, each module contains 2-5 series components and is equipped with an independent DC / DC converter to achieve maximum power point tracking (MPPT).

6. The system according to any one of claims 1 to 5, characterized in that The power prediction module in the intelligent controller receives real-time meteorological data and historical power generation data, predicts future photovoltaic power generation, and constructs a photovoltaic power generation prediction formula based on the real-time meteorological data and historical power generation data. The photovoltaic power generation prediction formula is: Among them, G (t) is the real-time irradiance (W / m 2 );T (t) is the photovoltaic panel temperature (℃); T ref is the standard test temperature; β is the temperature power attenuation coefficient, typically 0.3-0.5%; η is the overall efficiency, usually 15%-25%; A is the effective area of the photovoltaic array (m 2 );P hist,avg (t during the same period) is the average power generation during the same period in history; P hist,base It is the historical benchmark power generation, used to eliminate the impact of changes in installed capacity.

7. The system according to claim 6, characterized in that The economic dispatch module is used to determine the charging and discharging strategy of the energy storage system based on electricity prices, load demand and energy storage status; the charging and discharging strategy includes: based on the high and low electricity price periods, the size of the load demand, and the remaining power and health status of the energy storage status, the charging and discharging power and time of the energy storage system are determined by a preset algorithm or model; the preset algorithm or model includes: when the electricity price is in a low price period and the energy storage status has not reached full power, the charging power is determined according to the predicted value of the load demand to maximize the charging amount while meeting the load demand; when the electricity price is in a high price period and the energy storage status has dischargeable power, the discharge power is determined according to the predicted value of the load demand to reduce the purchase of electricity from the power grid while meeting the load demand; the economic dispatch method also includes adjusting the charging and discharging strategy according to the health status of the energy storage status. When the health status of the energy storage system is not good, the charging and discharging power is reduced to protect the energy storage system.

8. The system according to claim 7, characterized in that The device protection module is used to monitor the working status of photovoltaic components, energy storage systems and inverters, and execute protection strategies when an abnormality occurs; the device protection module includes a monitoring unit for monitoring the working status of photovoltaic components, energy storage systems and inverters, and an execution unit for executing protection strategies when an abnormality is detected in the working status of the photovoltaic components, energy storage systems or inverters; the monitoring unit includes sensors connected to the photovoltaic components, energy storage systems and inverters respectively, the sensors are used to obtain parameters representing the working status, and the execution unit determines whether an abnormality occurs based on the parameters obtained by the sensors; the sensors include but are not limited to temperature sensors , voltage sensor, current sensor, the execution unit determines whether an abnormality occurs based on the comparison of parameters such as temperature, voltage, current and preset thresholds; the protection strategy includes a power adjustment strategy for photovoltaic component abnormalities, a charge and discharge control strategy for energy storage system abnormalities and a circuit switching strategy for inverter abnormalities; when the execution unit determines that the temperature of the photovoltaic component exceeds the preset temperature range, it executes the protection strategy by reducing its operating power; when the energy storage system voltage exceeds the preset voltage range, it adjusts its charge and discharge state to execute the protection strategy; when the inverter current exceeds the preset current range, it switches the circuit to execute the protection strategy.

9. A photovoltaic energy storage collaborative power generation method, characterized in that: The following steps are involved: (a) Arrange the photovoltaic array in a predetermined ratio facing east and west, so that the power of the east-facing modules and the west-facing modules connected to the same inverter are equal or the difference is less than 10%; (b) configuring fixed strings and switchable strings to be connected in parallel to the inverter, wherein the power ratio of the fixed strings to the switchable strings is 30%-70%; (c) Real-time monitoring of the inverter output power through an intelligent controller; (d) When the output power of the inverter reaches 90%-95% of its rated value, the switchable strings are switched from the inverter to the energy storage battery for direct charging via the intelligent switch; (e) When the output power of the inverter is lower than 85% of its rated value or during the peak electricity price period, the energy storage battery is switched to discharge to the grid through the energy storage converter; (f) Maintain the system's capacity ratio at 1.5-3, where the capacity ratio is defined as the ratio of the total DC-side power of the inverter to the rated AC-side output power.

10. The method according to claim 9, characterized in that Steps (d) and (e) further include: (d1) when the inverter output power reaches 90%-95% of the rated value, gradually switching to the energy storage battery in increments of no more than 10% of the total switchable string capacity each time; (e1) when the inverter output power is lower than 85% of the rated value, gradually switching back to the inverter in increments of no more than 10% of the total capacity of the energy storage battery each time.

Images