A control method for a photovoltaic energy storage system, a photovoltaic energy storage system and a control circuit.

Abstract

This application provides a control method, a photovoltaic energy storage system, and a control circuit for a photovoltaic energy storage system. The photovoltaic energy storage system includes a power supply mechanism, a hybrid energy storage mechanism, and a control module. The hybrid energy storage mechanism includes a supercapacitor module and an energy storage module. The control method dynamically adjusts the hysteresis control threshold based on real-time state information from multiple dimensions. It collects grid-side data, photovoltaic-side data, and load-side data in real time and calculates various power gap parameters and state change parameters. If the state change parameter triggers the transient response strategy in the hybrid energy storage hierarchical control strategy, the supercapacitor module is controlled to compensate first. If the steady-state control strategy in the hybrid energy storage hierarchical control strategy is triggered, the energy storage module and the supercapacitor module are controlled to connect to the DC bus for compensation based on the dynamically adjusted hysteresis control threshold and the matching results of the various power gap parameters, thereby reducing the state switching frequency of the photovoltaic energy storage system.

Description

Technical Field

[0001] This application relates to the field of photovoltaic energy storage, and more specifically, to a control method for a photovoltaic energy storage system, a photovoltaic energy storage system, and a control circuit. Background Technology

[0002] Currently, with the popularization of photovoltaic energy storage systems, especially residential photovoltaic energy storage systems, they face the impact of complex environments such as load fluctuations, battery SOC fluctuations, and changes in external grid frequency and voltage. When there are fluctuations in sunlight or changes in load, the operating state will switch, resulting in the system starting and stopping or the battery charging and discharging state switching. Because the strategy of traditional photovoltaic energy storage systems to control the charging and discharging state of the system based on the fluctuation of sunlight or changes in load is relatively simple, the system operating state switches frequently, which leads to the rapid decay of battery cycle life and the reduction of inverter life due to frequent switching of operating conditions. Summary of the Invention

[0003] In view of this, the purpose of this application is to provide a control method, a photovoltaic energy storage system and a control circuit for a photovoltaic energy storage system, which can reduce the state switching frequency of the photovoltaic energy storage system, extend battery life and improve power supply stability.

[0004] This application provides a control method for a photovoltaic energy storage system. The control method is applied to the photovoltaic energy storage system, which includes: a power supply mechanism, a hybrid energy storage mechanism, and a control module. The hybrid energy storage mechanism includes a supercapacitor module and an energy storage module. The power supply mechanism includes photovoltaic modules and an inverter. The supercapacitor module and the energy storage module are connected to a DC bus, and the mains power and the photovoltaic modules are connected to the DC bus through the inverter. The control module collects the bus voltage signal and the inverter signal, and controls the inverter, the supercapacitor module, the energy storage module, the grid feedback interface, and the load operation.

[0005] The control method includes the following steps:

[0006] The control module dynamically adjusts the SOC change threshold and the bus voltage change threshold in the hysteresis control threshold based on real-time status information from multiple dimensions on the photovoltaic side and the load side, thus obtaining the dynamically adjusted hysteresis control threshold.

[0007] Real-time data collection from the grid side, photovoltaic side, and load side is performed, and various power gap parameters and state change parameters are calculated. The various power gap parameters are calculated based on the power gap between different power supply capabilities and load demands. The state change parameters include the bus voltage change rate and the load current change rate. The various power supply capabilities include: photovoltaic power generation, photovoltaic power generation and supercapacitor module combined power supply, and photovoltaic power generation, supercapacitor module and energy storage module combined power supply.

[0008] The state mutation parameters are repeatedly detected according to the first preset detection cycle to determine whether they meet the preset mutation conditions.

[0009] If the conditions are met, the transient response strategy in the hybrid energy storage hierarchical control strategy is triggered, and the supercapacitor module is controlled to connect to the DC bus for priority compensation during the detection period.

[0010] If the conditions are not met, the steady-state control strategy in the hybrid energy storage hierarchical control strategy is triggered. Within the second preset detection period, based on the dynamically adjusted hysteresis control threshold and the matching results of the various power gap parameters, the energy storage module and the supercapacitor module are controlled to connect to the DC bus for compensation.

[0011] In some embodiments, the control method for the photovoltaic energy storage system, wherein controlling the supercapacitor module to connect to the DC bus for priority compensation during the detection cycle includes:

[0012] Based on the state change parameters, the PWM duty cycle of the first DC / DC module in the supercapacitor module is dynamically adjusted to dynamically adjust the charging and discharging power of the supercapacitor module.

[0013] In some embodiments, in the control method of the photovoltaic energy storage system, detecting whether the state change parameter meets the preset change condition includes:

[0014] Detect whether the rate of change of the bus voltage is greater than a preset rate of change threshold;

[0015] And / or,

[0016] Detect whether the rate of change of the load current is greater than a preset rate of change of current threshold.

[0017] In some embodiments, the control method for the photovoltaic energy storage system, wherein controlling the energy storage module and the supercapacitor module to connect to the DC bus for compensation based on the dynamically adjusted hysteresis control threshold and the matching results of the various different power deficit parameters, includes:

[0018] When the first power gap corresponding to photovoltaic power generation is greater than 0, it indicates that there is a photovoltaic surplus. If the SOC of the energy storage module battery is lower than the upper limit of the capacity, the battery is controlled to charge. If the energy storage module battery is full, the supercapacitor module is controlled to charge.

[0019] If the first power gap corresponding to photovoltaic power generation is less than 0, it indicates that the photovoltaic power is insufficient. If the SOC of the supercapacitor module is greater than 20% and the second power gap of photovoltaic power generation and supercapacitor module jointly supplying power is greater than 0, the supercapacitor module discharges based on the first power gap.

[0020] If the supercapacitor module has insufficient power or the second power gap is less than 0, the battery will discharge.

[0021] In some embodiments, the control method for the photovoltaic energy storage system includes controlling battery charging, which comprises:

[0022] If the SOC of the energy storage module battery is lower than the upper limit of the capacity, the battery will be controlled to charge at a preset minimum charging power of 0.5C.

[0023] The control of charging the supercapacitor module includes:

[0024] The supercapacitor module is controlled to charge according to the current state of charge ratio.

[0025] In some embodiments, in the control method of the photovoltaic energy storage system, the control module dynamically adjusts the SOC change threshold and the bus voltage change threshold in the hysteresis control threshold based on real-time state information from multiple dimensions of the photovoltaic side and the load side, to obtain the dynamically adjusted hysteresis control threshold; including:

[0026] Acquire meteorological data and battery health status parameters on the photovoltaic side, as well as load power change rate and ambient temperature on the load side;

[0027] Based on the meteorological data and battery health status parameters of the photovoltaic side, the SOC change threshold in the hysteresis control threshold is dynamically adjusted to obtain the dynamically adjusted SOC change threshold.

[0028] Based on the load power change rate on the load side, the preset power change rate threshold, and the bus voltage hysteresis threshold in the ambient temperature dynamic adjustment hysteresis control threshold, the dynamically adjusted hysteresis control threshold is obtained; wherein, the preset power change rate threshold is determined based on the equivalent inertial time constant, frequency deviation, and response time of the supercapacitor module of the photovoltaic energy storage system.

[0029] In some embodiments, the control method for the photovoltaic energy storage system, wherein dynamically adjusting the SOC change threshold in the hysteresis control threshold based on meteorological data and battery health status parameters on the photovoltaic side to obtain the dynamically adjusted SOC change threshold includes:

[0030] The SOC change threshold is adjusted in real time based on real-time irradiance and cloud cover forecast to obtain the SOC change threshold after the first adjustment.

[0031] The dynamically adjusted SOC change threshold is obtained by compensating the first adjusted SOC change threshold based on the battery health status parameters.

[0032] In some embodiments, the control method for the photovoltaic energy storage system, wherein obtaining the dynamically adjusted hysteresis control threshold based on the load power change rate on the load side, a preset power change rate threshold, and the bus voltage hysteresis threshold in the dynamic adjustment hysteresis control threshold for ambient temperature includes:

[0033] The bus voltage hysteresis threshold is adjusted based on the peak value of the load power change rate and the preset power change rate threshold to obtain the bus voltage hysteresis threshold after the first adjustment.

[0034] The adjusted bus voltage hysteresis threshold is corrected based on the ambient temperature to obtain the dynamically adjusted hysteresis control threshold.

[0035] In some embodiments, a photovoltaic energy storage system is also provided, comprising: a power supply mechanism, a hybrid energy storage mechanism, and a control module; the hybrid energy storage mechanism includes a supercapacitor module and an energy storage module; the power supply mechanism includes photovoltaic modules and an inverter; the supercapacitor module and the energy storage module are connected to a DC bus, and the mains power and the photovoltaic modules are connected to the DC bus through the inverter; the control module acquires the bus voltage signal and the inverter signal, and controls the inverter, the supercapacitor module, the energy storage module, the grid feedback interface, and the load operation;

[0036] The photovoltaic energy storage system executes the control method of the photovoltaic energy storage system.

[0037] In some embodiments, a control circuit for a photovoltaic energy storage system is also provided, the control circuit comprising: a hybrid energy storage circuit, an inverter, and a controller; the hybrid energy storage circuit comprising a supercapacitor module and an energy storage module;

[0038] The DC bus of the photovoltaic energy storage system is connected to the bus voltage detection terminals of the supercapacitor module, energy storage module, inverter, and controller in the hybrid energy storage circuit.

[0039] The inverter is connected to the mains power interface and the photovoltaic array of the photovoltaic energy storage system, and the inverter is connected to the controller.

[0040] The controller is connected to the supercapacitor module, energy storage module, load, and grid feedback interface.

[0041] In some embodiments, in the control circuit of the photovoltaic energy storage system, the supercapacitor module includes a supercapacitor module and a first DC / DC converter; the supercapacitor module is connected to the controller, and the supercapacitor module is connected to the DC bus through the first DC / DC converter;

[0042] The energy storage module includes an energy storage module and a second DC / DC converter; the energy storage module is connected to the controller, and the energy storage module is connected to the DC bus through the second DC / DC converter.

[0043] This application provides a control method, a photovoltaic energy storage system, and a control circuit for a photovoltaic energy storage system. The control method is applied to the photovoltaic energy storage system, which includes a power supply mechanism, a hybrid energy storage mechanism, and a control module. The hybrid energy storage mechanism includes a supercapacitor module and an energy storage module. The power supply mechanism includes a photovoltaic module and an inverter. The supercapacitor module and the energy storage module are connected to a DC bus, and the mains power and the photovoltaic module are connected to the DC bus through the inverter. The control module collects the bus voltage signal and the inverter signal, and controls the inverter, the supercapacitor module, the energy storage module, the grid feedback interface, and the load operation. The method dynamically adjusts the hysteresis control threshold based on real-time state information from multiple dimensions to obtain the dynamically adjusted hysteresis control threshold. The hysteresis control threshold includes the SOC change threshold and the bus voltage change threshold. Real-time data is collected from the grid side, photovoltaic side, and load side, and various power gap parameters and state change parameters are calculated for each. These various power gap parameters are calculated based on power gaps between different power supply capacities and load demands. The state change parameters include the bus voltage change rate and the load current change rate. The various power supply capacities include: photovoltaic power generation, photovoltaic power generation combined with supercapacitor modules, and so on. The power supply, photovoltaic power generation, supercapacitor module, and energy storage module share the power supply. The system cyclically checks whether the state change parameters meet preset change conditions according to a first preset detection cycle. If they do, the transient response strategy in the hybrid energy storage hierarchical control strategy is triggered, and the supercapacitor module is controlled to connect to the DC bus for priority compensation within that detection cycle. If they do not meet the conditions, the steady-state control strategy in the hybrid energy storage hierarchical control strategy is triggered. Within a second preset detection cycle, based on the dynamically adjusted hysteresis control threshold and the matching results of various power gap parameters, the energy storage module and supercapacitor module are controlled to connect to the DC bus for... Compensation; The photovoltaic energy storage system adopts a DC bus architecture with hierarchical load management circuitry for optimization, enabling instantaneous compensation through direct DC bus connection. Based on the DC bus architecture, an adaptive hysteresis control algorithm is used to reduce inverter switching and battery charging / discharging actions. This is combined with a hybrid energy storage dynamic allocation strategy to reduce charging / discharging actions in short time periods. Furthermore, during the adaptive hysteresis control algorithm, dual threshold dynamic adjustments are made for both SOC change threshold and bus voltage change threshold to achieve complementarity and avoid strategy conflicts, thereby improving battery cycle life, reducing inverter losses, and enhancing power supply stability. Attached Figure Description

[0044] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 A flowchart of the control method for the photovoltaic energy storage system described in the embodiments of this application is shown;

[0046] Figure 2 A schematic diagram of the structure of the photovoltaic energy storage system described in the embodiment of this application is shown;

[0047] Figure 3 This paper shows an overall flowchart of the control method for the photovoltaic energy storage system described in an embodiment of the present application;

[0048] Figure 4 The flowchart of the method for dynamically adjusting the SOC change threshold and the bus voltage change threshold in the hysteresis control threshold according to an embodiment of this application is shown.

[0049] Figure 5 A flowchart of the method for dynamically adjusting the SOC change threshold in the hysteresis control threshold according to an embodiment of this application is shown;

[0050] Figure 6 A flowchart of the method for dynamically adjusting the bus voltage hysteresis threshold in the hysteresis control threshold according to an embodiment of this application is shown. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the accompanying drawings in this application are for illustrative and descriptive purposes only and are not intended to limit the scope of protection of this application. Furthermore, it should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this application illustrate operations implemented according to some embodiments of this application. It should be understood that the operations in the flowcharts may not be implemented in sequence, and steps without logical contextual relationships may be reversed or implemented simultaneously. In addition, those skilled in the art, guided by the content of this application, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts.

[0052] Furthermore, the described embodiments are merely some, not all, of the embodiments of this application. The components of the embodiments of this application described and illustrated herein can typically be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0053] It should be noted that the term "comprising" will be used in the embodiments of this application to indicate the presence of the features declared thereafter, but does not exclude the addition of other features.

[0054] This application provides a control method, a photovoltaic energy storage system, and a control circuit for a photovoltaic energy storage system. The control method is applied to the photovoltaic energy storage system, which includes a power supply mechanism, a hybrid energy storage mechanism, and a control module. The hybrid energy storage mechanism includes a supercapacitor module and an energy storage module. The power supply mechanism includes a photovoltaic module and an inverter. The supercapacitor module and the energy storage module are connected to a DC bus, and the mains power and the photovoltaic module are connected to the DC bus through the inverter. The control module collects the bus voltage signal and the inverter signal, and controls the inverter, the supercapacitor module, the energy storage module, the grid feedback interface, and the load operation. The method dynamically adjusts the hysteresis control threshold based on real-time state information from multiple dimensions to obtain the dynamically adjusted hysteresis control threshold. The hysteresis control threshold includes the SOC change threshold and the bus voltage change threshold. Real-time data is collected from the grid side, photovoltaic side, and load side, and various power gap parameters and state change parameters are calculated for each. These various power gap parameters are calculated based on power gaps between different power supply capacities and load demands. The state change parameters include the bus voltage change rate and the load current change rate. The various power supply capacities include: photovoltaic power generation, photovoltaic power generation combined with supercapacitor modules, and so on. The power supply, photovoltaic power generation, supercapacitor module, and energy storage module share the power supply. The system cyclically checks whether the state change parameters meet preset change conditions according to a first preset detection cycle. If they do, the transient response strategy in the hybrid energy storage hierarchical control strategy is triggered, and the supercapacitor module is controlled to connect to the DC bus for priority compensation within that detection cycle. If they do not meet the conditions, the steady-state control strategy in the hybrid energy storage hierarchical control strategy is triggered. Within a second preset detection cycle, based on the dynamically adjusted hysteresis control threshold and the matching results of various power gap parameters, the energy storage module and supercapacitor module are controlled to connect to the DC bus for... Compensation; The photovoltaic energy storage system adopts a DC bus architecture with hierarchical load management circuitry for optimization, enabling instantaneous compensation through direct DC bus connection. Based on the DC bus architecture, an adaptive hysteresis control algorithm is used to reduce inverter switching and battery charging / discharging actions. This is combined with a hybrid energy storage dynamic allocation strategy to reduce charging / discharging actions in short time periods. Furthermore, during the adaptive hysteresis control algorithm, dual threshold dynamic adjustments are made for both SOC change threshold and bus voltage change threshold to achieve complementarity and avoid strategy conflicts, thereby improving battery cycle life, reducing inverter losses, and enhancing power supply stability.

[0055] Please refer to Figure 1 and Figure 2 , Figure 1 A flowchart of the control method for the photovoltaic energy storage system described in the embodiments of this application is shown. Figure 2 A schematic diagram of the photovoltaic energy storage system described in an embodiment of this application is shown; as follows: Figure 1 and Figure 2 As shown, the control method is applied to a photovoltaic energy storage system, which includes: a power supply mechanism, a hybrid energy storage mechanism, and a control module; the hybrid energy storage mechanism includes a supercapacitor module and an energy storage module; the power supply mechanism includes photovoltaic modules and an inverter; the supercapacitor module and the energy storage module are connected to a DC bus, and the mains power and the photovoltaic modules are connected to the DC bus through the inverter; the control module collects the bus voltage signal and the inverter signal, and controls the inverter, the supercapacitor module, the energy storage module, the grid feedback interface, and the load operation;

[0056] The control method includes the following steps S101-S105:

[0057] S101. The control module dynamically adjusts the SOC change threshold and the bus voltage change threshold in the hysteresis control threshold based on real-time status information from multiple dimensions of the photovoltaic side and the load side, so as to obtain the dynamically adjusted hysteresis control threshold.

[0058] S102. Real-time acquisition of grid-side data, photovoltaic-side data, and load-side data, and calculation of various power gap parameters and state change parameters; the various power gap parameters are calculated based on various power supply capabilities and load demands; the state change parameters include bus voltage change rate and load current change rate; the various power supply capabilities include: photovoltaic power generation, photovoltaic power generation and supercapacitor module combined power supply, and photovoltaic power generation, supercapacitor module and energy storage module combined power supply;

[0059] S103. Detect whether the state mutation parameter meets the preset mutation condition according to the first preset detection cycle;

[0060] S104. If the conditions are met, the transient response strategy in the hybrid energy storage hierarchical control strategy is triggered, and the supercapacitor module is controlled to connect to the DC bus for priority compensation during the detection cycle.

[0061] S105. If not met, the steady-state control strategy in the hybrid energy storage hierarchical control strategy is triggered. Within the second preset detection period, based on the dynamically adjusted hysteresis control threshold and the matching results of the various different power gap parameters, the energy storage module and the supercapacitor module are controlled to connect to the DC bus for compensation.

[0062] Please refer to Figure 3 , Figure 3 A flowchart illustrating the overall process of the control method for the photovoltaic energy storage system described in the embodiments of this application is shown.

[0063] like Figure 3As shown, for a photovoltaic energy storage system, system initialization is performed after the control method of the photovoltaic energy storage system is started (e.g., after installation or restart).

[0064] During system initialization, the hardware status is read first, and the core parameters of the hardware status are as follows.

[0065] Battery SOC (State of Charge): Reflects the remaining percentage of battery charge and is used to determine the battery's charging and discharging status.

[0066] Supercapacitor voltage: directly reflects the energy storage state of the supercapacitor, and is measured in volts (V).

[0067] Bus voltage: DC bus voltage ( The core voltage nodes of the system must be maintained within a stable range.

[0068] Then set the initial parameters, which include hysteresis control threshold, mode flag, etc.

[0069] The hysteresis control threshold includes (SOC change threshold) and (The threshold for bus voltage change, i.e., the voltage hysteresis threshold).

[0070] =±5% (default value) This indicates the allowable range of battery SOC variation. For example, if the battery SOC drops from 50% to 46% without exceeding the threshold (±5%), the battery charging / discharging action will not be triggered.

[0071] A threshold characterizing the change in bus voltage, for example, =±2%×400V=±8V, This indicates the permissible range of bus voltage variation. For example, if the bus voltage rises from 400V to 405V without exceeding the threshold (±8V), voltage regulation will not be triggered.

[0072] The mode flag, Mode = IDLE, indicates that the system is initially in idle mode, waiting for a trigger condition (such as power fluctuation or voltage change) to switch to another mode (such as TRANSIENT or STEADY). Here, Mode is the mode identifier, IDLE represents the idle state, TRANSIENT represents the transient state, and STEADY represents the steady state.

[0073] In some embodiments, based on hysteresis-based instantaneous control, the system is configured with a response delay of <100μs; the voltage hysteresis width is ±2% of the bus rated voltage.

[0074] In step S101, the hysteresis control threshold is dynamically adjusted based on real-time status information from multiple dimensions to obtain the dynamically adjusted hysteresis control threshold; the hysteresis control threshold includes the SOC change threshold and the bus voltage change threshold.

[0075] For details, please refer to Figure 4 The control module dynamically adjusts the SOC change threshold and the bus voltage change threshold in the hysteresis control threshold based on real-time status information from multiple dimensions on the photovoltaic side and the load side, to obtain the dynamically adjusted hysteresis control threshold; including the following steps S401-S403:

[0076] S401. Obtain meteorological data and battery health status parameters from the photovoltaic side, and obtain the load power change rate and ambient temperature from the load side.

[0077] S402. Based on the meteorological data and battery health status parameters of the photovoltaic side, dynamically adjust the SOC change threshold in the hysteresis control threshold to obtain the dynamically adjusted SOC change threshold.

[0078] S403. Based on the load power change rate on the load side, the preset power change rate threshold, and the bus voltage hysteresis threshold in the ambient temperature dynamic adjustment hysteresis control threshold, a dynamically adjusted hysteresis control threshold is obtained; wherein, the preset power change rate threshold is determined based on the equivalent inertial time constant, frequency deviation, and response time of the supercapacitor module of the photovoltaic energy storage system.

[0079] It should be noted that the response timing of the SOC change threshold in the dynamic adjustment of the hysteresis control threshold and the bus voltage hysteresis threshold in the dynamic adjustment of the bus voltage hysteresis threshold are different. The timing of the dynamic adjustment of the SOC change threshold is on the order of minutes, while the timing of the dynamic adjustment of the bus voltage hysteresis threshold is on the order of seconds. This is because ΔSOC controls the energy storage rhythm, while the bus voltage hysteresis threshold controls the power flow response speed to ensure instantaneous stability. The difference in their timing allows for timing complementarity, thus balancing long-term monitoring and instantaneous adjustment to a certain extent. For details, please refer to [link / reference]. Figure 5 In an optional embodiment, the control method for the photovoltaic energy storage system, wherein the step of dynamically adjusting the SOC change threshold in the hysteresis control threshold based on the meteorological data and battery health status parameters on the photovoltaic side to obtain the dynamically adjusted SOC change threshold includes the following steps S501-S502:

[0080] S501. Adjust the SOC change threshold in real time based on real-time irradiance and cloud cover forecast to obtain the SOC change threshold after the first adjustment.

[0081] S502. Based on the battery health status parameters, compensate the first adjusted SOC change threshold to obtain the dynamically adjusted SOC change threshold.

[0082] For details, please refer to Figure 6 In an optional embodiment, the control method for the photovoltaic energy storage system, wherein obtaining the dynamically adjusted hysteresis control threshold based on the load power change rate on the load side, a preset power change rate threshold, and the bus voltage hysteresis threshold in the dynamic adjustment hysteresis control threshold for ambient temperature, includes:

[0083] S601. Adjust the bus voltage hysteresis threshold based on the peak value of the load power change rate and the preset power change rate threshold to obtain the bus voltage hysteresis threshold after the first adjustment.

[0084] S602. Based on the ambient temperature, the adjusted bus voltage hysteresis threshold is corrected to obtain the dynamically adjusted hysteresis control threshold.

[0085] In some embodiments, the preset power change rate threshold is determined based on the equivalent inertial time constant, frequency deviation, and response time of the supercapacitor module of the photovoltaic energy storage system.

[0086] Specifically, the SOC hysteresis width (ΔSOC) is dynamically adjusted, with the goal of optimizing the charge and discharge frequency based on weather conditions and battery state of health (SOH).

[0087] The SOC change threshold is adjusted in real time based on real-time irradiance and forecast cloud cover to obtain the first adjusted SOC change threshold. Specifically, the input driven by the weather prediction model is real-time irradiance. Weather forecast cloud cover data .in, In this context, G represents solar radiation intensity, with units of 1000 ppm. (Watts per square meter); In the variable, C is the weather indicator, and its value ranges from 0 to 1. When the value is 0, it means that the weather is sunny.

[0088] The adjustment formula for adjusting the SOC change threshold in real time based on real-time irradiance and forecast cloud cover is as follows:

[0089] ;

[0090] in, The base value is 40%, which can be dynamically adjusted according to the season or month based on historical big data models; α is the irradiance impact coefficient, for example, 0.5; β is the cloud cover impact coefficient, for example, 0.3. For maximum irradiance, for example, 1000 W / m 2 .

[0091] Here are some examples of adjustments:

[0092] Sunny day (G=900 W / m) 2 (C=0.1):

[0093] .

[0094] Cloudy (G=300 W / m) 2 (C=0.8):

[0095] .

[0096] The dynamically adjusted SOC change threshold is obtained by compensating the first adjusted SOC change threshold based on the battery health status parameters.

[0097] Specifically, the input to the battery state of health (SOH) compensation model is the SOH (0~100%) reported by the BMS.

[0098] The correction formula for battery state of health (SOH) compensation is as follows:

[0099] ;

[0100] The battery state of health (SOH) compensation effect is as follows: it reduces hysteresis when the battery ages (SOH↓), avoiding the risk of overcharging / over-discharging.

[0101] The goal of dynamically adjusting the voltage hysteresis threshold (ΔVbus) is to optimize voltage stability based on the frequency of load abrupt changes.

[0102] The peak value of the load power change rate within a preset time period is obtained, and adjustments are made based on historical load fluctuation statistics.

[0103] The bus voltage hysteresis threshold is adjusted based on the peak value of the load power change rate and a preset power change rate threshold. For example, the peak value of the load power change rate over the past hour is obtained. .

[0104] The formula for adjusting the bus voltage hysteresis threshold is: ；

[0105] Where, ΔV base This represents the base threshold, for example, 8V; γ represents the adjustment coefficient, for example, 0.5. Indicates the mutation rate of the load. Power change rate threshold; the tanh function is used for smooth transition. When the load change rate is close to the threshold, the tanh output is close to 0, and the reading remains stable. When the load change rate is significantly greater than the threshold, the tanh output approaches +1, and the threshold is amplified proportionally. When the load change rate is significantly less than the threshold, the tanh output approaches -1, and the threshold is reduced proportionally.

[0106] The following are some examples of adjusting the bus voltage hysteresis threshold based on the peak value of the load power change rate and the preset power change rate threshold.

[0107] Low volatility ( =0.5kW / s):

[0108] .

[0109] High volatility ( ):

[0110] ≈8*(1+0.46)≈11.7V.

[0111] The adjusted bus voltage hysteresis threshold is corrected based on ambient temperature, with the ambient temperature T (°C) as the input. The correction formula is as follows:

[0112] ;

[0113] Among them, K temp For temperature coefficients, the threshold is relaxed at low temperatures; for example, K. temp It is 0.002 / ℃; Characterizes the adjusted bus voltage hysteresis threshold.

[0114] Temperature compensation is used to adjust the upper and lower limits of SOC according to temperature, so that the energy storage battery capacity is in the optimal range and the battery life is improved.

[0115] In some embodiments, a power change rate threshold is also performed ( The system dynamically adjusts the transient response sensitivity according to the system's inertial requirements.

[0116] Based on the equivalent inertial time constant, frequency deviation, and response time of the supercapacitor module of the photovoltaic energy storage system, the preset power change rate threshold is determined. Specifically, the inputs to the virtual inertial model are: the system equivalent inertial time constant H (s) and the frequency deviation Δf (Hz); the adjustment formula is: ；

[0117] in =0.1 s is the response time of the supercapacitor.

[0118] When the hysteresis control threshold is dynamically adjusted based on real-time state information from multiple dimensions to obtain the dynamically adjusted hysteresis control threshold, the parameter update period is as follows: High-frequency parameters (ΔV) bus ): Updated every 10ms, calculated by FPGA hardware acceleration; Intermediate frequency parameter (ΔSOC): Updated every minute, based on weather API data; Low frequency parameter (SOH compensation): Updated every hour, reported by BMS. API stands for Application Programming Interface, used to acquire external data.

[0119] In step S102, grid-side data, photovoltaic-side data, and load-side data are collected in real time, and various different power gap parameters and state change parameters are calculated respectively. The various different power gap parameters are calculated based on the power gap of various different power supply capabilities and load demands. The state change parameters include the bus voltage change rate and the load current change rate. The various different power supply capabilities include: photovoltaic power generation, photovoltaic power generation and supercapacitor module combined power supply, and photovoltaic power generation, supercapacitor module and energy storage module combined power supply.

[0120] The photovoltaic (PV) side data is as follows: PV voltage and current (MPPT algorithm input). Additionally, weather forecast APIs (irradiance, cloud cover) can be obtained, or historical data can be combined to train a model to predict power generation. Here, the MPPT algorithm is the maximum power point tracking algorithm.

[0121] The load-side data is as follows: total power (Hall sensor), load type (smart meter classification), and can be further integrated with a load prediction model.

[0122] The grid-side data are as follows: mains voltage / frequency, and time-of-use pricing periods.

[0123] The following calculations were performed for various power gap parameters and state transition parameters.

[0124] The power gap parameter is: ΔP1 = P pv - P load ;

[0125] ΔP2= P pv + P sc - P load ;

[0126] ΔP3= P pv + P sc + P bat - P load ;

[0127] Voltage change rate: dV / dt = ( - ) / Δt.

[0128] Among them, P pv Characterized by photovoltaic power generation; P sc Characterizing supercapacitor power; P bat Characterizing battery power; P load Characterizes load power; Characterizes the DC bus voltage.

[0129] In steps S103-S105, the state change parameter is cyclically checked according to the first preset detection cycle to see if it meets the preset change condition. If it does, the transient response strategy in the hybrid energy storage hierarchical control strategy is triggered, and the supercapacitor module is controlled to connect to the DC bus for priority compensation within the detection cycle. If it does not meet the condition, the steady-state control strategy in the hybrid energy storage hierarchical control strategy is triggered, and the energy storage module and supercapacitor module are controlled to connect to the DC bus for compensation within the second preset detection cycle based on the dynamically adjusted hysteresis control threshold and the matching results of the various power gap parameters.

[0130] The detection of whether the state mutation parameter meets the preset mutation conditions includes:

[0131] The system detects whether the rate of change of the bus voltage is greater than a preset voltage change rate threshold; for example, the preset voltage change rate threshold can be 1 V / ms.

[0132] And / or,

[0133] The detection is performed to determine whether the load current change rate is greater than a preset current change rate threshold. For example, the preset current change rate threshold can be 10 A / ms.

[0134] Please refer to Figure 2 The preset sudden change conditions are voltage change rate > 1V / ms and power change rate > 1kW / s. If these conditions are met, the system is considered to have a transient response requirement (such as a sudden drop in photovoltaic power or a sudden increase in load). Supercapacitors are given priority for compensation, and they respond quickly to power shortages or absorb excess energy (such as millisecond-level response).

[0135] The step of controlling the supercapacitor module to be connected to the DC bus for priority compensation during the detection cycle includes:

[0136] Based on the aforementioned state change parameters, the PWM duty cycle of the first DC / DC module in the supercapacitor module is dynamically adjusted to dynamically adjust the charging and discharging power of the supercapacitor module. Here, PWM stands for Pulse Width Modulation.

[0137] Update the supercapacitor's SOC to monitor and update the supercapacitor's state of charge in real time to ensure its continuous availability; determine whether the transient response has ended (e.g., the power / voltage change rate has recovered to within the threshold), and if not, continue the loop.

[0138] The steady-state control strategy in the triggering hybrid energy storage stratified control strategy can be triggered directly without triggering the transient response strategy, or it can be triggered after the transient response strategy has finished adjusting.

[0139] Based on the dynamically adjusted hysteresis control threshold and the matching results of various different power deficit parameters, the energy storage module and supercapacitor module are controlled to connect to the DC bus for compensation, including:

[0140] When the first power gap corresponding to photovoltaic power generation is greater than 0, it indicates that there is a photovoltaic surplus. If the SOC of the energy storage module battery is lower than the upper limit of the capacity, the battery is controlled to charge. If the energy storage module battery is full, the supercapacitor module is controlled to charge.

[0141] If the first power gap corresponding to photovoltaic power generation is less than 0, it indicates that the photovoltaic power is insufficient. If the SOC of the supercapacitor module is greater than 20% and the second power gap of photovoltaic power generation and supercapacitor module jointly supplying power is greater than 0, the supercapacitor module discharges based on the first power gap.

[0142] If the supercapacitor module has insufficient power or the second power gap is less than 0, the battery will discharge.

[0143] The control of battery charging includes:

[0144] If the SOC of the energy storage module battery is lower than the upper limit of the capacity, the battery will be controlled to charge at a preset minimum charging power of 0.5C.

[0145] The control of charging the supercapacitor module includes:

[0146] The supercapacitor module is controlled to charge according to the current state of charge ratio.

[0147] The steady-state power distribution is controlled by software, with a second preset detection cycle of 100ms.

[0148] Scenario 1: Photovoltaic overcapacity (ΔP1>0):

[0149] If SOC bat <SOC upper (Maximum battery capacity), battery charging (P) bat =min(ΔP, 0.5C)), min(ΔP, 0.5C) means charging the battery at a preset minimum charging power of 0.5C; if the energy storage module battery is full, then control the supercapacitor module to charge, and the supercapacitor charging (P) sc = ΔP × SOC sc / 100). Among them, SOC bat Characterizes the state of charge (P) of a battery;bat Characterizing the charge and discharge power of a battery; SOC sc Characterizing the state of charge of a supercapacitor; P sc Characterizes the charging and discharging power of a supercapacitor.

[0150] Case 2: Insufficient photovoltaic power (ΔP1<0); if SOC sc If the discharge rate is >20% and ΔP2≥0, then the supercapacitor discharges (P sc = ΔP1); otherwise the battery will discharge.

[0151] Please refer to Table 1 below, which shows the mode switching logic of the mode state machine in this application embodiment:

[0152] Table 1

[0153] .

[0154] Wherein, IDLE represents the idle mode; dV / dt represents the rate of voltage change; TRANSIENT represents the transient mode; STEADY represents the steady-state mode; and SOC represents the stable mode. bat Characterizes the state of charge of the battery; FAULT characterizes the failure mode.

[0155] In some embodiments, the control method for the photovoltaic energy storage system further includes a protection mechanism, which includes real-time monitoring and graded protection.

[0156] Specifically, for batteries, the real-time monitoring triggers BMS protection when the single-cell voltage is >3.65V or <2.5V; for supercapacitors, it forcibly disconnects the DC / DC converter when the voltage is >16V or the temperature is >65℃. Here, BMS stands for Battery Management System.

[0157] The aforementioned graded protection, specifically, Level 1 (Warning): SOC sc <10% → Issue alarm signal and operate at reduced rating; Level 2 (fault): Bus voltage >450V → Hard shut down all MOSFETs.

[0158] MOSFET stands for Semiconductor Field-Effect Transistor, a type of electronic switching device.

[0159] The actuator commands of the control module are as follows: Supercapacitor DC / DC: PWM duty cycle (0%~100%); Battery DC / DC: Constant current / constant voltage mode switching (CC / CV); Load relay: K1 / K2 on / off (magnetic latching relay drive current 500mA).

[0160] Among them, DC / DC is a DC-DC converter, the supercapacitor DC / DC is a DC-DC converter that converts between the voltage of the supercapacitor and the DC bus voltage, i.e., the first DC / DC converter; the battery DC / DC is a DC-DC converter that converts between the battery voltage and the DC bus voltage, i.e., the second DC / DC converter; CC / CV represents constant current / constant voltage; K1 and K2 are the relay numbers.

[0161] The data recording method of the photovoltaic energy storage system control method is as follows: the storage event log includes timestamps, modes, SOC, power values, etc., which are used to update the power generation prediction model, load prediction model, and adjust the upper or lower limit of SOC.

[0162] When a system shutdown command is received, or three consecutive Level 2 faults are triggered, the control method of the photovoltaic energy storage system is stopped.

[0163] It should be noted that the execution of the dual-threshold dynamic adjustment and the hybrid energy storage hierarchical control strategy are both closely related to the DC bus architecture of the photovoltaic energy storage system. The DC bus frame, i.e., the DC bus of the photovoltaic energy storage system, connects the supercapacitor module and the energy storage module, inverter, and controller in the hybrid energy storage circuit to the bus voltage detection terminals. The supercapacitor module is directly connected to the bus, achieving a second-level transient response, enabling timely response. Sudden changes are compensated instantaneously; photovoltaic / energy storage / load currents are all aggregated at the bus node, and the control module directly acquires the bus voltage signal, ensuring global voltage consistency, regardless of power shortages or... The calculations are more precise.

[0164] Based on the same inventive concept, this application also provides a photovoltaic energy storage system corresponding to the control method of the photovoltaic energy storage system. Since the principle of solving the problem by the photovoltaic energy storage system in this application is similar to the control method of the photovoltaic energy storage system described above in this application, the implementation of the photovoltaic energy storage system can refer to the implementation of the control method of the photovoltaic energy storage system, and the repeated parts will not be described again.

[0165] In some embodiments, a photovoltaic energy storage system is also provided, such as Figure 2 As shown, the photovoltaic energy storage system includes: a power supply mechanism, a hybrid energy storage mechanism, and a control module; the hybrid energy storage mechanism includes a supercapacitor module and an energy storage module; the power supply mechanism includes photovoltaic modules and an inverter; the supercapacitor module and the energy storage module are connected to the DC bus, and the mains power and the photovoltaic modules are connected to the DC bus through the inverter; the control module collects the bus voltage signal and the inverter signal, and controls the inverter, the supercapacitor module, the energy storage module, the grid feedback interface, and the load operation;

[0166] The photovoltaic energy storage system executes the control method of the photovoltaic energy storage system, specifically including:

[0167] The control module dynamically adjusts the SOC change threshold and the bus voltage change threshold in the hysteresis control threshold based on real-time status information from multiple dimensions on the photovoltaic side and the load side, thus obtaining the dynamically adjusted hysteresis control threshold.

[0168] Real-time data collection from the grid side, photovoltaic side, and load side is performed, and various power gap parameters and state change parameters are calculated. The various power gap parameters are calculated based on the power gap between different power supply capabilities and load demands. The state change parameters include the bus voltage change rate and the load current change rate. The various power supply capabilities include: photovoltaic power generation, photovoltaic power generation and supercapacitor module combined power supply, and photovoltaic power generation, supercapacitor module and energy storage module combined power supply.

[0169] The state mutation parameters are repeatedly detected according to the first preset detection cycle to determine whether they meet the preset mutation conditions.

[0170] If the conditions are met, the transient response strategy in the hybrid energy storage hierarchical control strategy is triggered, and the supercapacitor module is controlled to connect to the DC bus for priority compensation during the detection period.

[0171] If the conditions are not met, the steady-state control strategy in the hybrid energy storage hierarchical control strategy is triggered. Within the second preset detection period, based on the dynamically adjusted hysteresis control threshold and the matching results of the various power gap parameters, the energy storage module and the supercapacitor module are controlled to connect to the DC bus for compensation.

[0172] In some embodiments, when the photovoltaic energy storage system performs the step of controlling the supercapacitor module to connect to the DC bus for priority compensation during the detection cycle, the following steps are specifically executed:

[0173] Based on the state change parameters, the PWM duty cycle of the first DC / DC module in the supercapacitor module is dynamically adjusted to dynamically adjust the charging and discharging power of the supercapacitor module.

[0174] In some embodiments, when the photovoltaic energy storage system performs the step of detecting whether the state change parameter meets the preset change condition, it specifically performs the following steps:

[0175] Detect whether the rate of change of the bus voltage is greater than a preset rate of change threshold;

[0176] And / or,

[0177] Detect whether the rate of change of the load current is greater than a preset rate of change of current threshold.

[0178] In some embodiments, when the photovoltaic energy storage system executes the step of controlling the energy storage module and the supercapacitor module to connect to the DC bus for compensation based on the dynamically adjusted hysteresis control threshold and the matching results of various different power deficit parameters, the following steps are specifically performed:

[0179] When the first power gap corresponding to photovoltaic power generation is greater than 0, it indicates that there is a photovoltaic surplus. If the SOC of the energy storage module battery is lower than the upper limit of the capacity, the battery is controlled to charge. If the energy storage module battery is full, the supercapacitor module is controlled to charge.

[0180] If the first power gap corresponding to photovoltaic power generation is less than 0, it indicates that the photovoltaic power is insufficient. If the SOC of the supercapacitor module is greater than 20% and the second power gap of photovoltaic power generation and supercapacitor module jointly supplying power is greater than 0, the supercapacitor module discharges based on the first power gap.

[0181] If the supercapacitor module has insufficient power or the second power gap is less than 0, the battery will discharge.

[0182] In some embodiments, when the photovoltaic energy storage system performs the step of controlling battery charging, it specifically performs the following steps:

[0183] If the SOC of the energy storage module battery is lower than the upper limit of the capacity, the battery will be controlled to charge at a preset minimum charging power of 0.5C.

[0184] The control of charging the supercapacitor module includes:

[0185] The supercapacitor module is controlled to charge according to the current state of charge ratio.

[0186] In some embodiments, when the photovoltaic energy storage system performs the step of dynamically adjusting the SOC change threshold and the bus voltage change threshold in the hysteresis control threshold based on real-time status information from multiple dimensions on the photovoltaic side and the load side, to obtain the dynamically adjusted hysteresis control threshold, the following steps are specifically executed:

[0187] Acquire meteorological data and battery health status parameters on the photovoltaic side, as well as load power change rate and ambient temperature on the load side;

[0188] Based on the meteorological data and battery health status parameters of the photovoltaic side, the SOC change threshold in the hysteresis control threshold is dynamically adjusted to obtain the dynamically adjusted SOC change threshold.

[0189] Based on the load power change rate on the load side, the preset power change rate threshold, and the bus voltage hysteresis threshold in the ambient temperature dynamic adjustment hysteresis control threshold, the dynamically adjusted hysteresis control threshold is obtained; wherein, the preset power change rate threshold is determined based on the equivalent inertial time constant, frequency deviation, and response time of the supercapacitor module of the photovoltaic energy storage system.

[0190] In some embodiments, when the photovoltaic energy storage system performs the step of dynamically adjusting the SOC change threshold in the hysteresis control threshold based on the meteorological data and battery health status parameters on the photovoltaic side to obtain the dynamically adjusted SOC change threshold, the following steps are specifically executed:

[0191] The SOC change threshold is adjusted in real time based on real-time irradiance and cloud cover forecast to obtain the SOC change threshold after the first adjustment.

[0192] The dynamically adjusted SOC change threshold is obtained by compensating the first adjusted SOC change threshold based on the battery health status parameters.

[0193] In some embodiments, when the photovoltaic energy storage system performs the step of obtaining the dynamically adjusted hysteresis control threshold based on the load power change rate on the load side, a preset power change rate threshold, and the ambient temperature dynamic adjustment hysteresis control threshold, the following steps are specifically executed:

[0194] The bus voltage hysteresis threshold is adjusted based on the peak value of the load power change rate and the preset power change rate threshold to obtain the bus voltage hysteresis threshold after the first adjustment.

[0195] The adjusted bus voltage hysteresis threshold is corrected based on the ambient temperature to obtain the dynamically adjusted hysteresis control threshold.

[0196] Based on the same inventive concept, this application also provides a control circuit corresponding to the control method of the photovoltaic energy storage system. Since the principle of the control circuit in this application is similar to the control method of the photovoltaic energy storage system described above, the implementation of the photovoltaic energy storage system can refer to the implementation of the control method of the photovoltaic energy storage system. Repeated parts will not be described again.

[0197] Please refer to Figure 2 The control circuit described in this application embodiment includes: a hybrid energy storage circuit, an inverter, and a controller; the hybrid energy storage circuit includes a supercapacitor module and an energy storage module;

[0198] The DC bus of the photovoltaic energy storage system is connected to the bus voltage detection terminals of the supercapacitor module, energy storage module, inverter, and controller in the hybrid energy storage circuit.

[0199] The inverter is connected to the mains power interface and the photovoltaic array of the photovoltaic energy storage system, and the inverter is connected to the controller.

[0200] The controller is connected to the supercapacitor module, energy storage module, load, and grid feedback interface.

[0201] In some embodiments, in the control circuit of the photovoltaic energy storage system, the supercapacitor module includes a supercapacitor module and a first DC / DC converter; the supercapacitor module is connected to the controller, and the supercapacitor module is connected to the DC bus through the first DC / DC converter;

[0202] The energy storage module includes an energy storage module and a second DC / DC converter; the energy storage module is connected to the controller, and the energy storage module is connected to the DC bus through the second DC / DC converter.

[0203] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems and devices described above can be referred to the corresponding processes in the method embodiments, and will not be repeated here. In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed mutual coupling or direct coupling or communication connection can be through some communication interfaces; the indirect coupling or communication connection of devices or modules can be electrical, mechanical, or other forms.

[0204] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0205] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0206] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, a platform server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0207] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A control method for a photovoltaic energy storage system, characterized in that, The control method is applied to a photovoltaic energy storage system, which includes: a power supply mechanism, a hybrid energy storage mechanism, and a control module. The hybrid energy storage mechanism includes a supercapacitor module and an energy storage module; the power supply mechanism includes a photovoltaic module and an inverter; the supercapacitor module and the energy storage module are connected to the DC bus, and the mains power and the photovoltaic module are connected to the DC bus through the inverter; the control module collects the bus voltage signal and the inverter signal, and controls the inverter, the supercapacitor module, the energy storage module, the grid feedback interface and the load operation. The control method includes the following steps: The control module dynamically adjusts the SOC change threshold and the bus voltage hysteresis threshold in the hysteresis control threshold based on real-time status information from multiple dimensions on the photovoltaic side and the load side, thereby obtaining the dynamically adjusted hysteresis control threshold. Real-time data collection from the grid side, photovoltaic side, and load side is performed, and various power gap parameters and state change parameters are calculated. The various power gap parameters are calculated based on the power gap between different power supply capabilities and load demands. The state change parameters include the bus voltage change rate and the load current change rate. The various power supply capabilities include: photovoltaic power generation, photovoltaic power generation and supercapacitor module combined power supply, and photovoltaic power generation, supercapacitor module and energy storage module combined power supply. The state mutation parameters are repeatedly detected according to the first preset detection cycle to determine whether they meet the preset mutation conditions. If the conditions are met, the transient response strategy in the hybrid energy storage hierarchical control strategy is triggered, and the supercapacitor module is controlled to connect to the DC bus for priority compensation during the detection period. If the conditions are not met, the steady-state control strategy in the hybrid energy storage hierarchical control strategy is triggered. Within the second preset detection period, based on the dynamically adjusted hysteresis control threshold and the matching results of the various power gap parameters, the energy storage module and the supercapacitor module are controlled to connect to the DC bus for compensation.

2. The control method for a photovoltaic energy storage system according to claim 1, characterized in that, The step of controlling the supercapacitor module to be connected to the DC bus for priority compensation during the detection cycle includes: Based on the state change parameters, the PWM duty cycle of the first DC / DC module in the supercapacitor module is dynamically adjusted to dynamically adjust the charging and discharging power of the supercapacitor module.

3. The control method for the photovoltaic energy storage system according to claim 1 or 2, characterized in that, The detection of whether the state mutation parameter meets the preset mutation conditions includes: Detect whether the rate of change of the bus voltage is greater than a preset rate of change threshold; And / or, Detect whether the rate of change of the load current is greater than a preset rate of change of current threshold.

4. The control method for a photovoltaic energy storage system according to claim 1, characterized in that, Based on the dynamically adjusted hysteresis control threshold and the matching results of various different power deficit parameters, the energy storage module and supercapacitor module are controlled to connect to the DC bus for compensation, including: When the first power gap corresponding to photovoltaic power generation is greater than 0, it indicates that there is a photovoltaic surplus. If the SOC of the energy storage module battery is lower than the upper limit of the capacity, the battery is controlled to charge. If the energy storage module battery is full, the supercapacitor module is controlled to charge. If the first power gap corresponding to photovoltaic power generation is less than 0, it indicates that the photovoltaic power is insufficient. If the SOC of the supercapacitor module is greater than 20% and the second power gap of photovoltaic power generation and supercapacitor module jointly supplying power is greater than 0, the supercapacitor module discharges based on the first power gap. If the supercapacitor module has insufficient power or the second power gap is less than 0, the battery will discharge.

5. The control method for a photovoltaic energy storage system according to claim 4, characterized in that, The control of battery charging includes: If the SOC of the energy storage module battery is lower than the upper limit of the capacity, the battery will be controlled to charge at a preset minimum charging power of 0.5C. The control of charging the supercapacitor module includes: The supercapacitor module is controlled to charge according to the current state of charge ratio.

6. The control method for a photovoltaic energy storage system according to claim 1, characterized in that, The control module dynamically adjusts the SOC change threshold and the bus voltage hysteresis threshold in the hysteresis control threshold based on real-time status information from multiple dimensions on the photovoltaic side and the load side, resulting in a dynamically adjusted hysteresis control threshold; including: Acquire meteorological data and battery health status parameters on the photovoltaic side, as well as load power change rate and ambient temperature on the load side; Based on the meteorological data and battery health status parameters of the photovoltaic side, the SOC change threshold in the hysteresis control threshold is dynamically adjusted to obtain the dynamically adjusted SOC change threshold. Based on the load power change rate on the load side, the preset power change rate threshold, and the bus voltage hysteresis threshold in the ambient temperature dynamic adjustment hysteresis control threshold, the dynamically adjusted hysteresis control threshold is obtained; wherein, the preset power change rate threshold is determined based on the equivalent inertial time constant, frequency deviation, and response time of the supercapacitor module of the photovoltaic energy storage system.

7. The control method for a photovoltaic energy storage system according to claim 6, characterized in that, The process of dynamically adjusting the SOC change threshold in the hysteresis control threshold based on the meteorological data and battery health status parameters on the photovoltaic side, to obtain the dynamically adjusted SOC change threshold, includes: The SOC change threshold is adjusted in real time based on real-time irradiance and cloud cover forecast to obtain the SOC change threshold after the first adjustment. The dynamically adjusted SOC change threshold is obtained by compensating the first adjusted SOC change threshold based on the battery health status parameters.

8. The control method for a photovoltaic energy storage system according to claim 6, characterized in that, The dynamically adjusted hysteresis control threshold is obtained by considering the load power change rate on the load side, the preset power change rate threshold, and the bus voltage hysteresis threshold in the ambient temperature dynamic adjustment hysteresis control threshold. This includes: The bus voltage hysteresis threshold is adjusted based on the peak value of the load power change rate and the preset power change rate threshold to obtain the bus voltage hysteresis threshold after the first adjustment. The adjusted bus voltage hysteresis threshold is corrected based on the ambient temperature to obtain the dynamically adjusted hysteresis control threshold.

9. A photovoltaic energy storage system, characterized in that, The photovoltaic energy storage system includes: a power supply mechanism, a hybrid energy storage mechanism, and a control module; the hybrid energy storage mechanism includes a supercapacitor module and an energy storage module; the power supply mechanism includes photovoltaic modules and an inverter; the supercapacitor module and the energy storage module are connected to the DC bus, and the mains power and the photovoltaic modules are connected to the DC bus through the inverter; the control module collects the bus voltage signal and the inverter signal, and controls the inverter, the supercapacitor module, the energy storage module, the grid feedback interface, and the load operation; The photovoltaic energy storage system implements the control method of the photovoltaic energy storage system according to any one of claims 1-8.

10. A control circuit for a photovoltaic energy storage system, characterized in that, The control circuit is applied to the photovoltaic energy storage system of claim 9; the control circuit includes: a hybrid energy storage circuit, an inverter, and a controller; the hybrid energy storage circuit includes a supercapacitor module and an energy storage module; The DC bus of the photovoltaic energy storage system is connected to the bus voltage detection terminals of the supercapacitor module, energy storage module, inverter, and controller in the hybrid energy storage circuit. The inverter is connected to the mains power interface and the photovoltaic array of the photovoltaic energy storage system, and the inverter is connected to the controller. The controller is connected to the supercapacitor module, energy storage module, load, and grid feedback interface.

11. The control circuit of the photovoltaic energy storage system according to claim 10, characterized in that, The supercapacitor module includes a supercapacitor module and a first DC / DC converter; The supercapacitor module is connected to the controller, and the supercapacitor module is connected to the DC bus through the first DC / DC converter; The energy storage module includes an energy storage module and a second DC / DC converter; The energy storage module is connected to the controller, and the energy storage module is connected to the DC bus through a second DC / DC converter.

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