Photovoltaic energy storage system, control method, control device, equipment and storage medium

Abstract

The invention provides a photovoltaic energy storage system, a control method, a control device, equipment and a storage medium, and solves the problem that hardware is overheated and aged due to an inappropriate control mode in related technologies by adjusting the working mode of the first converter in the photovoltaic energy storage system. Specifically, when the output power of the photovoltaic module is not enough to meet the load requirement, the first converter is controlled to work in a first mode (for example, an MPPT mode), and it is ensured that the photovoltaic module outputs the maximum power under the current illumination condition. According to the mode, the energy utilization efficiency of the photovoltaic module is effectively improved, and meanwhile, the problem of hardware overheating caused by continuous working in the first mode is avoided, so that the service life of system hardware is prolonged, and the overall reliability and operation efficiency of the system are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power generation, and in particular to a photovoltaic energy storage system, a control method, a control device, equipment and a storage medium. Background Art

[0002] Photovoltaic energy storage system is a system that converts solar energy into electrical energy and can store or use this electrical energy according to demand. The system can use solar energy to generate electricity and power the load, and at the same time store excess electricity for use when photovoltaic power generation is insufficient (such as at night or on cloudy days). Photovoltaic energy storage systems are widely used in home, commercial, industrial and other scenarios, helping to achieve energy self-sufficiency and reduce dependence on traditional power grids.

[0003] In the related technology, in the photovoltaic energy storage system, there is a technical problem of inappropriate control method causing hardware overheating and aging. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned technical deficiencies and provide a photovoltaic energy storage system, control method, control device, equipment and storage medium to solve the technical problem in the related art that in the photovoltaic energy storage system, there is an inappropriate control method, which causes hardware overheating and aging.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a photovoltaic energy storage system, including a photovoltaic module, an energy storage battery, and further comprising:

[0007] A first converter, whose input end is connected to the photovoltaic module and whose output end is connected to the load via a DC bus; wherein the first converter is a converter for performing a voltage boost process on the output voltage of the photovoltaic module;

[0008] A second converter, wherein a first input / output terminal of the second converter is connected to the energy storage battery, and a second input / output terminal of the second converter is connected in parallel to the DC bus together with the first converter; wherein the second converter is a converter capable of boosting the output voltage of the energy storage battery to the DC bus voltage, or stepping down the DC bus voltage to a voltage suitable for the energy storage battery input;

[0009] The controller is respectively connected to the photovoltaic module, the first converter and the second converter, and is used to control the photovoltaic module to operate in the first mode only when the output power of the photovoltaic module is less than the power required by the load; wherein the first mode is a mode in which the first converter makes the photovoltaic module operate at the maximum power point.

[0010] In a second aspect, the present invention provides a control method for a photovoltaic energy storage system, wherein the photovoltaic energy storage system comprises a photovoltaic module and an energy storage battery, and the method comprises:

[0011] Determine the output power of the photovoltaic module and the required power of the load;

[0012] When the output power of the photovoltaic module is less than the required power of the load, the first converter is controlled to operate in a first mode; wherein the first converter is a converter for performing a voltage boost processing on the output voltage of the photovoltaic module; the first mode is a mode in which the first converter causes the photovoltaic module to operate at a maximum power point.

[0013] In a third aspect, the present invention provides a control device for a photovoltaic energy storage system, wherein the photovoltaic energy storage system comprises a photovoltaic module and an energy storage battery; the device comprises:

[0014] A determination module, which is used to determine the output power of the photovoltaic module and the required power of the load;

[0015] A control module, which is used to control the first converter to operate in a first mode when the output power of the photovoltaic module is less than the required power of the load; wherein the first converter is a converter for performing a voltage boost processing on the output voltage of the photovoltaic module; and the first mode is a mode in which the first converter causes the photovoltaic module to operate at a maximum power point.

[0016] In a fourth aspect, the present invention provides an electronic device comprising: a memory, and one or more processors communicatively connected to the memory; the memory stores instructions executable by the one or more processors, and the instructions are executed by the one or more processors so that the one or more processors implement the above-mentioned method.

[0017] In a fifth aspect, the present invention provides a computer-readable storage medium, wherein the computer program is stored in the computer-readable storage medium, and the computer program implements the above method when executed by a processor.

[0018] Beneficial effects:

[0019] The present invention solves the problem of hardware overheating and aging caused by inappropriate control methods in related technologies by adjusting the working mode of the first converter in the photovoltaic energy storage system. Specifically, when the output power of the photovoltaic module (the output power of the photovoltaic module) is insufficient to meet the load demand (the required power of the load), the first converter is controlled to operate in the first mode (for example, it can be the MPPT mode) to ensure that the photovoltaic module outputs the maximum power under the current lighting conditions. This method not only effectively improves the energy utilization efficiency of the photovoltaic module, but also avoids the problem of hardware overheating caused by continuous operation in the first mode, thereby extending the service life of the system hardware and improving the overall reliability and operating efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of a scenario example of a control method for a photovoltaic energy storage system provided by an embodiment of the present invention;

[0021] Figure 2 is a flow chart of a control method of a photovoltaic energy storage system provided by an embodiment of the present invention;

[0022] Figure 3 is a circuit diagram of a photovoltaic energy storage system provided by an embodiment of the present invention;

[0023] Figure 4 is a block diagram of a photovoltaic energy storage system provided by an embodiment of the present invention;

[0024] Figure 5 is a flow chart of a control method of a photovoltaic energy storage system provided by an embodiment of the present invention;

[0025] Figure 6 is a flow chart of a constant voltage and current limiting charging method provided by an embodiment of the present invention;

[0026] Figure 7 is a block diagram of a photovoltaic energy storage system provided by an embodiment of the present invention;

[0027] Figure 8 is a flow chart of a control method of a photovoltaic energy storage system provided by an embodiment of the present invention;

[0028] Fig. 9 is a block diagram of a photovoltaic energy storage system provided by an embodiment of the present invention;

[0029] Fig.10 is a flow chart of a control method of a photovoltaic energy storage system provided by an embodiment of the present invention;

[0030] Fig.11 is a block diagram of a photovoltaic energy storage device used in an embodiment of the present invention;

[0031] Fig.12It is a block diagram of an electronic device used in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0033] Overview:

[0034] Among the related technologies, with the rapid popularization of renewable energy, solar photovoltaic energy storage systems have been widely used in household, commercial and industrial fields.

[0035] The architecture of a photovoltaic energy storage system includes photovoltaic modules, energy storage batteries, a DC bus, and a converter electrically connected to the load. The output voltage of a photovoltaic module is usually low and unstable, and needs to be converted to a voltage suitable for the DC bus by a converter. The bidirectional converter in a photovoltaic energy storage system can achieve a bidirectional flow of energy, that is, charging the energy storage battery when there is surplus photovoltaic power, and supplying power to the load from the energy storage battery when there is insufficient power.

[0036] In one possible implementation, the MPPT mode is used to enable the photovoltaic module to output as much electrical energy as possible under various lighting conditions. MPPT continuously adjusts the working point of the photovoltaic module so that it is always in the maximum power output state. However, although the MPPT mode can maximize power output in the short term, its defects are gradually emerging, especially in scenarios with long-term operation. First, because the photovoltaic energy storage system continues to operate at a high power output state in the MPPT mode, the circuit components (for example, power devices, switching devices in the converter, etc.) are in a high-temperature working state for a long time. This long-term high-temperature working environment accelerates the aging of the hardware and reduces the overall reliability of the photovoltaic energy storage system. In addition, the continuous high-power output increases the current stress and voltage fluctuations in the circuit, which not only accelerates the aging of the components, but also increases the risk of electromagnetic interference (EMI). If the monitoring and protection circuits of the photovoltaic energy storage system fail to respond in time, this high-power operation may cause faults such as overvoltage and overcurrent, and even cause hardware damage. In addition, when it is not necessary to continue to work at the maximum power point, the unrestricted high-power operation of the photovoltaic energy storage system will also lead to energy waste and reduce the overall efficiency of the photovoltaic energy storage system.

[0037] Therefore, in view of the technical problem that in the photovoltaic energy storage system, there is an inappropriate control method in the related technology, which causes hardware overheating and aging. This application proposes a control method for a photovoltaic energy storage system, which can dynamically adjust the operation mode of the photovoltaic energy storage system to avoid always working at the maximum power point when it is not necessary, effectively prevent hardware overheating and aging, reduce the risk of system failure, and improve the stability and efficiency of system operation.

[0038] Example scenario:

[0039] like Figure 1 As shown, in this scenario example, it can be a home photovoltaic energy storage system. The home photovoltaic energy storage system can be configured with a 48V lithium-ion energy storage battery for storing electrical energy. The load can be lighting, refrigerators, air conditioners, etc. in the home. The photovoltaic module can be a solar panel. The first converter can be a Boost converter. The second converter can be a Buck-Boost converter. The controller can be an MCU (Microcontroller Unit). The DC bus voltage of the home photovoltaic energy storage system can be 400V. Therefore, the output voltage of the photovoltaic module can be boosted by the first converter. The second converter performs a bidirectional conversion function of boosting and bucking between the energy storage battery and the DC bus.

[0040] When the output power of the photovoltaic module (the output power of the photovoltaic module) is less than the required power of the household load (the required power of the load), for example, on cloudy days or when the light is weak, the household photovoltaic energy storage system needs to obtain as much photovoltaic power as possible. In this case, the MCU will adjust the Boost converter to the first mode (for example, it can be the MPPT mode) so that the photovoltaic module operates at the maximum power point. The MPPT algorithm preset in the controller will dynamically adjust the operating point of the photovoltaic module and control the duty cycle of the Boost converter to ensure that the photovoltaic module can output the maximum power under the current lighting conditions. In this way, the household photovoltaic energy storage system can obtain the maximum amount of electrical energy from the photovoltaic module.

[0041] Under normal circumstances, when the output power of the photovoltaic module (the output power of the photovoltaic module) is greater than or equal to the load demand power (the load demand power), for example, on a sunny day or when there is sufficient sunlight, the home photovoltaic energy storage can generate enough electricity to power the load. At this time, the MCU will control the Boost converter to enter the constant voltage mode, that is, it will no longer work in the MPPT mode, but supply power with a stable voltage to keep the DC bus voltage constant at 400V.

[0042] Therefore, the home photovoltaic energy storage system can intelligently adjust the working mode according to the actual photovoltaic power generation and load demand. When photovoltaic power generation is insufficient, the home photovoltaic energy storage system enters the MPPT mode to maximize power output; when photovoltaic power generation is sufficient, the home photovoltaic energy storage enters the constant voltage mode to maintain a stable voltage and reduce component loss. Through the constant voltage mode, the home photovoltaic energy storage system avoids long-term operation at the maximum power point, prevents hardware aging caused by overheating and high-power operation, and extends the service life of circuit components and systems.

[0043] Example method:

[0044] This embodiment provides a photovoltaic energy storage system, including a photovoltaic module, an energy storage battery, and further comprising:

[0045] A first converter has an input end connected to the photovoltaic module and an output end connected to a load via a DC bus; wherein the first converter is a converter for performing a voltage boost process on an output voltage of the photovoltaic module.

[0046] In this embodiment, the first converter may be a unidirectional converter. Specifically, the unidirectional converter may be a Boost converter. The Boost converter is a step-up DC-DC converter used to increase the lower output voltage of the photovoltaic module to a high voltage suitable for the DC bus.

[0047] In this embodiment, the first converter can be a bidirectional converter, which can both boost and buck, and can achieve bidirectional flow of energy. The bidirectional converter can boost the output voltage of the photovoltaic module to the DC bus voltage, and can also supply power to the photovoltaic module from the DC bus when necessary. Specifically, the bidirectional converter can be a Buck-Boost converter. The Buck-Boost converter can achieve dual functions of boosting and bucking. When the output voltage of the photovoltaic module is low, it can boost; when the output voltage is high, it can buck, so that the output voltage remains within a stable range.

[0048] In this embodiment, the first converter may also be a multi-phase Boost converter. The multi-phase Boost converter is a multi-channel parallel boost converter that can provide higher power capacity and better current distribution. Its multiple boost channels can work in parallel to improve efficiency and reduce current ripple.

[0049] In this embodiment, the first converter may also be a resonant converter. For example, it may be an LLC resonant converter. The LLC resonant converter can perform step-up or step-down conversion in a large power range with high efficiency, and is suitable for high-efficiency photovoltaic energy storage scenarios.

[0050] In this embodiment, the first converter may also be a full-bridge converter. Specifically, the full-bridge converter can handle higher power and realize energy conversion between the photovoltaic module and the DC bus through multiple switching devices (for example, IGBT or MOS tube). Efficient boost conversion can be achieved by controlling the switching sequence of the switching device. The full-bridge converter can be applied to high-power photovoltaic energy storage systems, with good control flexibility and high efficiency.

[0051] A second converter, whose first input / output terminal is connected to the energy storage battery, and whose second input / output terminal is connected in parallel to the DC bus together with the first converter; wherein the second converter is a converter capable of boosting the output voltage of the energy storage battery to the DC bus voltage, or stepping down the DC bus voltage to a voltage suitable for the energy storage battery input.

[0052] In this embodiment, the second converter can be a bidirectional converter, which can both boost and buck, and can achieve bidirectional flow of energy. The bidirectional converter can boost the output voltage of the energy storage battery to the DC bus voltage, and can also supply power to the energy storage battery from the DC bus when necessary. Specifically, the bidirectional converter can be a Buck-Boost converter. The Buck-Boost converter can achieve dual functions of boosting and bucking. When the output voltage of the energy storage battery is low, it can boost; when the energy storage battery is charged, it can buck to keep the output voltage within a stable range.

[0053] In this embodiment, the second converter may also be a resonant converter. For example, it may be an LLC resonant converter. The LLC resonant converter can perform step-up or step-down conversion in a large power range with high efficiency, and is suitable for high-efficiency photovoltaic energy storage scenarios.

[0054] The controller is respectively connected to the photovoltaic module, the first converter and the second converter, and is used to control the photovoltaic module to operate in the first mode only when the output power of the photovoltaic module is less than the power required by the load; wherein the first mode is a mode in which the first converter makes the photovoltaic module operate at the maximum power point.

[0055] In this embodiment, the controller may be an embedded microcontroller (e.g., an MCU). The controller may be a programmable logic controller (e.g., a PLC). The controller may also be an integrated energy management system (e.g., an EMS). The controller may also be a digital signal processor (e.g., a DSP).

[0056] like Figure 2As shown, this embodiment provides a control method for a photovoltaic energy storage system, and the control method can be applied to a photovoltaic energy storage system. The photovoltaic energy storage system may include a photovoltaic module and a load electrically connected thereto. It can be understood that the photovoltaic module and the load can be electrically connected via a DC bus. Specifically, the photovoltaic module may be composed of one or more photovoltaic cells. The photovoltaic cell may be a monocrystalline silicon photovoltaic panel, a polycrystalline silicon photovoltaic panel, or a thin-film photovoltaic panel, etc. The load may be a household appliance or an industrial equipment. More specifically, the household appliance may be a refrigerator, an air conditioner, a lighting system, or other household appliances. The industrial equipment may be industrial appliances such as motors, compressors, and production equipment.

[0057] It is understandable that a photovoltaic module is a device that converts solar energy into electrical energy, and a load is a device that consumes the electrical energy. The specific type of load may depend on the specific application scenario of the photovoltaic energy storage system, which may be a household application scenario, an industrial scenario, or the like.

[0058] The method may be performed by a controller of a photovoltaic energy storage system, and the method may include:

[0059] Step S102: Determine the output power of the photovoltaic module and the required power of the load.

[0060] In this implementation, the determining action may be represented as an action in which the controller obtains and calculates the output power of the photovoltaic module and the required power of the load.

[0061] In this implementation, the determining the output power of the photovoltaic module and the required power of the load may include:

[0062] Step S1022: respectively obtain the current data and voltage data of the current photovoltaic module and the load.

[0063] Step S1024: Based on the current data and voltage data of the photovoltaic module, the output power of the photovoltaic module is calculated and obtained, and based on the current data and voltage data of the load, the required power of the load is calculated and obtained.

[0064] Specifically, the controller can obtain the output voltage and current of the photovoltaic module in real time through the sensor (for example, a voltage sensor and a current sensor) connected to the photovoltaic module. The controller can calculate the output power of the photovoltaic module (the output power of the photovoltaic module) through the obtained output voltage and current. The calculation action can be performed in real time (for example, once per second) to ensure that the output power of the photovoltaic module reflects the working state of the photovoltaic module under the current lighting conditions in real time. The calculation action can also be performed at a certain time interval. For example, it can be calculated once every minute or every five minutes.

[0065] The controller can detect the voltage and current of the load in real time through sensors connected to the load (for example, voltage sensors and current sensors), and then calculate the actual power demand of the load (the power demand of the load). Similarly, this calculation can also be performed in real time to ensure that the photovoltaic energy storage system can monitor the changes in load demand at any time.

[0066] In this embodiment, when there are multiple loads in the photovoltaic energy storage system, the controller first obtains the current data and voltage data of each load, and then performs aggregation to obtain the aggregated current data and voltage data. Based on the aggregated current data and voltage data, the required power of the load is calculated.

[0067] In this embodiment, when there are multiple loads in the photovoltaic energy storage system, the controller first obtains the current data and voltage data of each load, and then calculates the required sub-power of each load, and finally summarizes the required sub-power of the load to obtain the required power of the load.

[0068] In this embodiment, the controller may be an embedded microcontroller (e.g., an MCU). The controller may be a programmable logic controller (e.g., a PLC). The controller may also be an integrated energy management system (e.g., an EMS). The controller may also be a digital signal processor (e.g., a DSP).

[0069] When the photovoltaic energy storage system is used in a home scenario, the controller can communicate with the voltage sensor and the current sensor through simple analog signals. The voltage sensor can convert the voltage signal into a low-voltage signal and directly transmit it to the ADC module of the MCU for collection and processing.

[0070] When the photovoltaic energy storage system is used in industrial scenarios, the controller can communicate with the voltage sensor and the current sensor through an electrical isolation device to ensure safety and signal integrity in a high voltage environment. For example, the voltage sensor and the controller can be electrically isolated by means of an optical coupler, an isolation amplifier, etc. The voltage sensor can communicate with the controller through industrial bus protocols such as RS485 or CAN to ensure the stability and anti-interference ability of data transmission.

[0071] In a specific embodiment, the controller can be an MCU. The above-mentioned voltage sensor can output an analog signal proportional to the measured voltage. For example, the voltage sensor can convert a higher DC voltage (for example, the output voltage of a photovoltaic module) into an analog signal of a lower voltage range (for example, 0-5V), which is convenient for subsequent processing. Correspondingly, the current sensor outputs an analog signal proportional to the actual current, and the current can be measured by the Hall effect or a shunt, and the current signal is converted into a low-voltage analog signal. It is understandable that an analog-to-digital converter (ADC) can be integrated in the MCU to convert the analog signals output by the voltage sensor and the current sensor into digital signals, which is convenient for the controller to process. The analog output signals (for example, 0-5V or 0-10V) of the voltage sensor and the current sensor are connected to the ADC input pin of the controller. The analog-to-digital converter converts the voltage signal (or the processed current signal) into a digital value within a certain range. The controller calculates the actual voltage value and current value based on the collected digital signal. It is understandable that there will be a calibration formula matching the sensor inside the controller to convert the digital signal into an actual physical quantity (for example, voltage, current, etc.). The MCU can obtain current data and voltage data through an analog-to-digital converter at a certain sampling frequency.

[0072] The sampling frequency can be a low-speed sampling frequency or a high-speed sampling frequency. Specifically, if the photovoltaic energy storage system does not have high requirements for the real-time performance of voltage and current changes, for example, data can be collected once per second (1Hz), and the controller can sample at a lower frequency. If real-time and rapid response is required, the sampling rate can be as high as several thousand times or higher (such as 1kHz or higher).

[0073] Step S104: When the output power of the photovoltaic module is less than the required power of the load, control the first converter to operate in the first mode; wherein the first converter is a converter for performing a voltage boost processing on the output voltage of the photovoltaic module; and the first mode is a mode in which the first converter causes the photovoltaic module to operate at a maximum power point.

[0074] In this embodiment, the control action may mean that when the output power of the photovoltaic module is less than the required power of the load, the controller generates corresponding control instructions (for example, controlling the switching frequency or duty cycle of the switching device in the first converter, etc.) based on a preset control strategy (for example, it may be an MPPT algorithm) to adjust the working state of the first converter.

[0075] In this embodiment, the first converter may be a unidirectional converter. Specifically, the unidirectional converter may be a Boost converter. The Boost converter is a step-up DC-DC converter used to increase the lower output voltage of the photovoltaic module to a high voltage suitable for the DC bus.

[0076] In this embodiment, the first converter can be a bidirectional converter, which can both boost and buck, and can achieve bidirectional flow of energy. The bidirectional converter can boost the output voltage of the photovoltaic module to the DC bus voltage, and can also supply power to the photovoltaic module from the DC bus when necessary. Specifically, the bidirectional converter can be a Buck-Boost converter. The Buck-Boost converter can achieve dual functions of boosting and bucking. When the output voltage of the photovoltaic module is low, it can boost; when the output voltage is high, it can buck, so that the output voltage remains within a stable range.

[0077] In this embodiment, the first converter may also be a multi-phase Boost converter. The multi-phase Boost converter is a multi-channel parallel boost converter that can provide higher power capacity and better current distribution. Its multiple boost channels can work in parallel to improve efficiency and reduce current ripple.

[0078] In this embodiment, the first converter may also be a resonant converter. For example, it may be an LLC resonant converter. The LLC resonant converter can perform step-up or step-down conversion in a large power range with high efficiency, and is suitable for high-efficiency photovoltaic energy storage scenarios.

[0079] In this embodiment, the first converter may also be a full-bridge converter. Specifically, the full-bridge converter can handle higher power and realize energy conversion between the photovoltaic module and the DC bus through multiple switching devices (for example, IGBT or MOS tube). Efficient boost conversion can be achieved by controlling the switching sequence of the switching device. The full-bridge converter can be applied to high-power photovoltaic energy storage systems, with good control flexibility and high efficiency.

[0080] In this embodiment, the first mode may be an MPPT mode (Maximum Power Point Tracking). Specifically, the MPPT mode is a control strategy that aims to allow the photovoltaic module to output as much power as possible under any lighting conditions. Since the output power of the photovoltaic module is closely related to environmental factors (e.g., light intensity, temperature, etc.), the optimal operating point (i.e., maximum power point) of the photovoltaic module will change continuously under different conditions. The output power of the photovoltaic module has a nonlinear relationship with the output voltage. At a certain voltage point, the output power is the maximum, which is the maximum power point (MPP). Therefore, by measuring the output current and voltage of the photovoltaic module, the controller can adjust the operating parameters of the first converter (e.g., switching frequency, duty cycle) in real time to ensure that the photovoltaic module operates at the maximum power point. More specifically, the controller can continuously obtain the voltage data and current data of the photovoltaic module. Then, the preset MPPT algorithm adjusts the output voltage to find the maximum power point. The first converter dynamically adjusts the operating point of the photovoltaic module according to the calculation results of the MPPT algorithm to ensure the maximum power output.

[0081] In this embodiment, the first mode may be an incremental derivative mode. Specifically, the controller may determine whether the maximum power point has been reached by comparing the incremental derivatives of the output voltage and current of the photovoltaic module. If the derivative is zero, it indicates that the maximum power point has been reached. The controller acquires the voltage data and current data of the photovoltaic module in real time. The incremental derivative of the photovoltaic module is further calculated. By determining the value of the incremental derivative, the controller dynamically adjusts the output of the first converter to ensure that it operates at the maximum power point.

[0082] In this embodiment, the first mode may be a fuzzy control mode. Specifically, the controller may fuzzify the voltage and current readings output by the photovoltaic module to form a fuzzy set (for example, it may be "high", "medium", "low"). According to a preset fuzzy rule (for example, it may be "if the current is low and the voltage is high, increase the output voltage"), the controller generates a fuzzy control signal. The first converter adjusts the output according to the fuzzy control signal generated by the controller to optimize the power output of the photovoltaic module.

[0083] In this embodiment, the first mode can be a neural network control mode. The neural network control mode realizes dynamic control by training a neural network to learn the optimal operating point of the photovoltaic module under different environmental conditions. The controller can collect voltage and current data of the photovoltaic module in real time, and in some cases, environmental factors (for example, temperature, light intensity, etc.) can also be included. The controller inputs the real-time collected data into the trained neural network, and the neural network outputs the corresponding optimal control instructions. The first converter adjusts the output voltage and current according to the control instructions to achieve maximum power output.

[0084] In this embodiment, the first mode can also be a closed-loop control mode. Specifically, the controller collects voltage data and current data of the photovoltaic module and calculates the power. Then the real-time power is compared with the set maximum power value. Then the required output adjustment amount is calculated based on the difference between the real-time power and the set maximum power value, and then the corresponding control instruction is generated. The first converter adjusts the corresponding switch control festival according to the control instruction to adjust the output voltage and current to ensure that the power output is stable at the maximum value.

[0085] like Figure 3 As shown, in a specific embodiment, the first converter can be a Boost converter. The Boost converter is configured between the photovoltaic module and the load to convert the low-voltage, unstable direct current generated by the photovoltaic module into a stable, high-voltage direct current (DC bus voltage).

[0086] The Boost converter may include:

[0087] Inductor L1, the inductor L1 is configured on the DC bus, and one end of the inductor L1 is connected to the positive electrode of the photovoltaic module. The other end of the inductor L1 is connected to the input end of the switching device Q1 and the positive electrode of the diode D1 respectively. Specifically, the inductor L1 is used to store energy and smooth the current. When the switching device Q1 is turned on, the current passes through the inductor L1, and the inductor L1 stores enough energy for the boost process. When the switching device Q1 is turned off, due to the characteristic that the inductor current cannot change suddenly, the current remains relatively stable for a certain period of time, and the energy in the inductor L1 is released to the load through the diode D1.

[0088] The switch device Q1, the output end of the switch device Q1 is connected to the negative pole of the photovoltaic module. The switch device Q1 may also have a signal input end, which may be connected to the controller to receive the control signal of the controller, and then change the working mode according to the control signal of the controller. It is understandable that the control signal of the controller may change the working mode by controlling the switching frequency or duty cycle of the switch device Q1. Specifically, the switch device Q1 may be an IGBT or a MOS tube. The switch device Q1 is periodically turned on and off under the drive of the PWM control signal. During the on-time, the current flows from the photovoltaic module through the inductor L1 to store energy. During the off-time, the current flow is blocked, so that the inductor L1 begins to release the stored energy.

[0089] Capacitor C1, one end of the capacitor C1 is connected to the positive electrode of the photovoltaic module. The other end of the capacitor C1 is connected to the negative electrode of the photovoltaic module. Specifically, the capacitor C1 acts as a bus capacitor to smooth voltage fluctuations and ensure the stability of the DC bus voltage.

[0090] The diode D1 has a cathode connected to the load, specifically, the inverter circuit of the load. Specifically, the diode D1 serves as a freewheeling element. When the switch is disconnected, the current in the inductor L1 is allowed to continue to flow, transferring energy to the next stage. This prevents the current from flowing in the reverse direction, ensures the unidirectional flow of energy, and prevents the current of the load from being fed back to the photovoltaic module.

[0091] In this embodiment, when the output power of the photovoltaic module is less than the required power of the load, the first converter is controlled to operate in the first mode. Correspondingly, when the output power of the photovoltaic module is equal to or greater than the required power of the load, the first converter does not operate in the first mode. For example, it can operate in a constant voltage mode or other modes. Specifically, the other mode can be a constant current mode. In this mode, the output current of the first converter is maintained at a set value to ensure that the charging current does not exceed the safety limit of the load. The other mode can be a power limiting mode. In the power limiting mode, the first converter can limit its output power to not exceed the set value to prevent overload or overheating. The other mode can also be a load matching mode. In this load matching mode, the first converter can dynamically adjust the output according to the load demand to ensure that the energy supply matches the load demand and avoid waste.

[0092] In this way, only when the output power of the photovoltaic module is less than the required power of the load, the first converter is controlled to operate in the first mode to reduce the temperature of the hardware in the photovoltaic energy storage system and delay the aging of electronic components due to continuous high temperature.

[0093] It is understandable that if the first converter always operates at the maximum power point, the electronic components will generate heat when working, especially in the photovoltaic energy storage system, the first converter is in the first mode (for example, MPPT mode), and continuously processes a large amount of electrical energy, which may cause its operating temperature to increase significantly. Being in a high temperature state for a long time will accelerate the aging of electronic components (for example, capacitors and switching devices) and reduce their service life. By switching the first converter to a constant voltage mode or other low power consumption mode when the output power of the photovoltaic module is equal to or greater than the required power of the load, the controller can significantly reduce the operating temperature of the electronic components. This temperature management not only extends the service life of the components, but also reduces the probability of failure.

[0094] In a photovoltaic energy storage system, continuous operation in the first mode (for example, MPPT mode) may cause instantaneous and drastic fluctuations in current and voltage. If the monitoring and protection circuits cannot respond to these changes in time, overvoltage, overcurrent and other faults may occur, thereby damaging the circuits and equipment. Therefore, by switching to other control modes at the appropriate time, the photovoltaic energy storage system can effectively reduce power output, prevent electrical failures caused by overload, and ensure the safe and stable operation of the system.

[0095] When the photovoltaic energy storage system works at high power for a long time, it will generate more electromagnetic interference (EMI), which will have a negative impact on the stability of the photovoltaic energy storage system. This interference will not only affect other components inside the photovoltaic energy storage system, but may also affect surrounding equipment and systems. Therefore, by switching the working mode reasonably and controlling the output of the first converter, it is possible to reduce the generation of electromagnetic interference and enhance the stability of the photovoltaic energy storage system. This is especially important for photovoltaic energy storage systems that need to operate in sensitive environments.

[0096] In summary, this implementation solves the hardware overheating and aging problem caused by inappropriate control methods in related technologies by adjusting the working mode of the first converter in the photovoltaic energy storage system. Specifically, when the output power of the photovoltaic module (the output power of the photovoltaic module) is insufficient to meet the load demand (the required power of the load), the first converter is controlled to operate in the first mode (for example, it can be the MPPT mode) to ensure that the photovoltaic module outputs the maximum power under the current lighting conditions. This method not only effectively improves the energy utilization efficiency of the photovoltaic module, but also avoids the hardware overheating problem caused by continuous operation in the first mode, thereby extending the service life of the system hardware and improving the overall reliability and operation efficiency of the system.

[0097] In some cases, the energy storage batteries in the photovoltaic energy storage system may be low on power, especially when photovoltaic power generation is insufficient and the load demand is large. At this time, if the power of the energy storage battery is not replenished in time, the energy storage system may not be able to provide stable power output for the load. At the same time, directly applying the DC bus voltage to charge the energy storage battery may cause excessive voltage, damaging the health and life of the battery. Therefore, how to ensure that the photovoltaic module can charge the battery safely and efficiently when the energy storage battery is low on power, and protect the battery through appropriate voltage conversion, has become a key technical issue.

[0098] Therefore, in some embodiments, the photovoltaic energy storage system further includes an energy storage battery, and the energy storage battery is electrically connected to the photovoltaic module and the load. Specifically, the energy storage battery can be electrically connected to the DC bus through a second converter, and then electrically connected to the photovoltaic module and the load respectively.

[0099] like Figure 4 and Figure 5 As shown, the method may also include:

[0100] Step S106: when the output power of the photovoltaic module is less than the required power of the load, the real-time power value of the energy storage battery is obtained.

[0101] In this embodiment, the acquisition action can be expressed as an action of the controller to collect data on the real-time power value of the energy storage battery. Specifically, the controller can be communicatively connected to the battery management system (BMS) of the energy storage battery. The controller can send a data acquisition request to the battery management system of the energy storage battery. For example, the controller can send a data request to the battery management system through a communication interface (for example, CAN, RS485, etc.). The data acquisition request is a request for obtaining the real-time power value of the energy storage battery. It can be understood that a variety of methods can be preset in the battery management system to calculate the state of charge (SOC) of the energy storage battery, that is, the real-time power value. The multiple methods can be a current integration method or an open circuit voltage method, etc. The battery management system can send the real-time power value of the energy storage battery to the controller based on the data acquisition request.

[0102] In some embodiments, when the energy storage battery is not equipped with a battery management system, the acquisition action may be that the controller measures the terminal voltage of the energy storage battery through a voltage sensor, and estimates the SOC in combination with the characteristic curve of the voltage and SOC of the energy storage battery. It is understandable that the characteristic curve of the voltage and SOC of the energy storage battery may be preset in the controller. Therefore, after obtaining the terminal voltage of the energy storage battery, the measured terminal voltage may be matched with the characteristic curve of the voltage and SOC to obtain the real-time power value of the energy storage battery.

[0103] Step S108: Determine whether the real-time power value of the energy storage battery is less than a power threshold.

[0104] In this implementation, the power threshold may be a preset power threshold, for example, 20%, 50% or 70%.

[0105] In some embodiments, the power threshold may also be the minimum power level at which the energy storage battery can operate safely and stably. In this case, the power threshold may be used to ensure that the energy storage battery is not over-discharged during the charging and discharging process, thereby avoiding damage to the energy storage battery, while also ensuring the safety and reliability of the photovoltaic energy storage system under different working conditions.

[0106] In this implementation, the action of determining may be represented by the controller comparing the real-time power value of the energy storage battery with a power threshold value preset in the controller.

[0107] Step S110: when the real-time power value of the energy storage battery is less than the power threshold, control the second converter to operate in the second mode so that the photovoltaic module charges the energy storage battery; wherein the second converter is a converter capable of boosting the output voltage of the energy storage battery to a DC bus voltage, or stepping down the DC bus voltage to a voltage suitable for the energy storage battery input; the second mode is a mode in which the second converter steps down the DC bus voltage to a voltage suitable for the energy storage battery input.

[0108] In this embodiment, the second converter can be a bidirectional converter, which can both boost and buck, and can achieve bidirectional flow of energy. The bidirectional converter can boost the output voltage of the photovoltaic module to the DC bus voltage, and can also supply power to the photovoltaic module from the DC bus when necessary. Specifically, the bidirectional converter can be a Buck-Boost converter. The Buck-Boost converter can achieve dual functions of boosting and bucking. When the output voltage of the photovoltaic module is low, it can boost; when the output voltage is high, it can buck, so that the output voltage remains within a stable range.

[0109] In this embodiment, the second converter may also be a resonant converter. For example, it may be an LLC resonant converter. The LLC resonant converter can perform step-up or step-down conversion in a large power range with high efficiency, and is suitable for high-efficiency photovoltaic energy storage scenarios.

[0110] In this embodiment, the second mode may be a buck mode. The buck mode is used to convert a higher DC bus voltage into a lower output voltage. It can be used in the charging stage of the energy storage battery, and the high voltage of the DC bus is reduced to a voltage suitable for battery charging by the second converter.

[0111] In this embodiment, the second mode may be a constant voltage mode. The constant voltage mode may maintain the output voltage of the second converter (the voltage output to the energy storage battery) at a fixed level to ensure that the energy storage battery obtains a stable voltage during the charging process. To prevent overcharging and improve charging efficiency. It is understandable that even in the constant voltage mode, the second converter needs to step down the DC bus voltage to a voltage suitable for the energy storage battery input. For example, the fixed level is a level suitable for the voltage input of the energy storage battery.

[0112] In this embodiment, the second mode may be a constant current mode. The constant current mode may control the output current to be maintained at a set value, ensuring that the current during the charging process does not exceed the safe charging limit of the battery. It is understandable that even in the constant current mode, the second converter needs to step down the DC bus voltage to a voltage suitable for the energy storage battery input.

[0113] In this embodiment, the second mode may also be a charging restriction mode. In the charging restriction mode, the second converter dynamically adjusts the charging current and voltage according to the current state and temperature of the energy storage battery to avoid excessive impact on the energy storage battery and ensure safe charging. It is understandable that even in the charging restriction mode, the second converter needs to step down the DC bus voltage to a voltage suitable for the energy storage battery input.

[0114] In this embodiment, the second mode can also be a dynamic adjustment mode. In this dynamic adjustment mode, the second converter can dynamically adjust its output voltage and current (the voltage and current output by the second converter to the energy storage battery) according to the load demand and energy storage battery status monitored in real time. This mode can improve the charging efficiency and adapt to different working conditions. It is understandable that even in the dynamic adjustment mode, the second converter needs to step down the DC bus voltage to a voltage suitable for the energy storage battery input.

[0115] In this embodiment, the control action may be represented as the controller generating corresponding control instructions to instruct the second converter to switch to a proper working mode (eg, BUCK mode) and set appropriate parameters (eg, output voltage and current).

[0116] In this embodiment, the energy storage battery can be a lithium-ion battery, a lithium iron phosphate battery, a lead-acid battery, a lithium titanate battery, or a vanadium redox flow battery.

[0117] like Figure 3 As shown, in a specific embodiment, the second converter may be a Buck-Boost converter. The Buck-Boost converter may include:

[0118] Inductor L2, one end of which is connected to the positive electrode of the energy storage battery. The other end of the inductor L2 is connected to the common node of the two switching devices (Q2 and Q3). Inductor L2 can store and convert energy, increase or decrease voltage, and smooth current.

[0119] Two switching devices (Q2 and Q3), two switching devices (Q2 and Q3) are used to control the conversion direction of the current path and voltage, and their on and off conditions are complementary. The switching device Q2 and the switching device Q3 can be IGBTs or MOS tubes. The frequency and duty cycle of the switching device Q2 and the switching device Q3 control the entire Buck-Boost conversion process. Specifically, the switching device Q2 and the switching device Q3 can both be NMOS tubes. The drain of the switching device Q2 is connected to the DC bus. The source of the switching device Q2 is respectively connected to the other end of the inductor L2 and the drain of the switching device Q2. The source of the switching device Q2 is respectively connected to the negative electrode of the energy storage battery and the DC bus. The diode therein can be used as a freewheeling element, the inductor current cannot change suddenly, and the current is freewheeling through the diode; prevent the current from flowing in the opposite direction, and ensure the correct direction of the current path.

[0120] During the conduction phase (Q2 is on, Q3 is off), the current of the DC bus flows to the energy storage battery through the inductor L2, the inductor L2 stores energy, the current in the inductor L2 increases linearly, and the battery begins to charge. Q3 remains off to ensure unidirectional energy transfer.

[0121] During the shutdown phase (Q2 is off, Q3 is off), the stored energy in the inductor L2 cannot continue to flow through Q2, but is released to the energy storage battery through the diode. In this phase, the inductor current gradually decreases, completing the battery charging process. Q3 continues to remain off to ensure that the current flows in one direction and prevents energy from flowing back to the DC bus. The controller can dynamically adjust the on and off time of Q2 (i.e., adjust the duty cycle of the PWM signal) by detecting the voltage and current of the energy storage battery in real time to control the voltage and current of the energy storage battery charging. When the energy storage battery voltage is low, the duty cycle is large, and more energy is transferred to the energy storage battery; as the battery voltage increases, the duty cycle gradually decreases to reduce the charging current and prevent overcharging.

[0122] This implementation solves the problem of how to effectively charge the energy storage battery when the power is insufficient. When the photovoltaic energy storage system detects that the power of the energy storage battery is lower than the preset power threshold, the controller activates the second converter to operate in the second mode, reducing the higher voltage of the DC bus to a voltage suitable for charging the energy storage battery. This not only avoids the damage that high voltage may cause to the battery, but also improves the safety and efficiency of charging. In addition, the entire process implements intelligent management, allowing the photovoltaic energy storage system to be flexibly adjusted under different power requirements, thereby optimizing the overall performance of the photovoltaic energy storage system, extending the life of the energy storage battery, and ensuring the stable power supply of the photovoltaic energy storage system.

[0123] In some cases, the energy storage batteries in the photovoltaic energy storage system will undergo a constant current-constant voltage switching process during the charging process. In the traditional charging method, when the photovoltaic energy storage system switches from constant current charging to constant voltage charging, current spikes may occur. These peak currents will impact the battery and other components in the system, causing accelerated aging of the components, and may even cause overcurrent failures, affecting the stability and safety of the photovoltaic energy storage system. In addition, in the constant current mode, the current always remains at a high level, which can easily cause the temperature of the energy storage battery to rise, thereby affecting the charging efficiency and life of the energy storage battery. Therefore, how to effectively avoid the current spike problem during the charging process of the energy storage battery and ensure the smooth and efficient charging process has become a technical problem that needs to be solved.

[0124] Therefore, in some embodiments, the step of controlling the second converter to operate in the second mode may include:

[0125] Step S1102: During the charging process of the energy storage battery, an actual voltage value of the energy storage battery is obtained.

[0126] In this implementation, the acquisition action may be represented as an action in which the controller collects the actual voltage value from the energy storage battery through a preset sensor or communication interface.

[0127] In this implementation, the acquisition action may be real-time acquisition or timed acquisition.

[0128] Specifically, the controller can be connected to the voltage sensor of the energy storage battery to collect voltage data of the energy storage battery in real time. The voltage sensor directly measures the voltage across the energy storage battery and feeds the data back to the controller.

[0129] When the energy storage battery is equipped with a battery management system (BMS), the controller can send a data request to the battery management system through a communication protocol (for example, CAN, RS485, etc.) to obtain the current voltage value of the energy storage battery.

[0130] Step S1104: Determine whether the actual voltage value of the energy storage battery is less than a voltage threshold; wherein the voltage threshold is a voltage value less than a given voltage of the battery.

[0131] In this embodiment, the battery given voltage can be expressed as the target voltage of the energy storage battery when it is fully charged, that is, the maximum voltage value when the energy storage battery is fully charged. The battery given voltage can be preset by the energy storage battery manufacturer according to the chemical properties of the energy storage battery and the safety charging requirements.

[0132] In this embodiment, the voltage threshold refers to a critical voltage value used by the controller to determine whether to continue charging at the maximum current during the charging process. This voltage threshold can be lower than the given voltage of the battery. In the early stage of charging, the voltage of the energy storage battery is low, and the controller will charge the battery at a constant current with the maximum current. When the battery voltage reaches the voltage threshold, the photovoltaic energy storage system will gradually reduce the charging current and maintain a constant voltage. This can avoid current spikes caused by sudden changes in current, protect the battery and improve charging efficiency.

[0133] In a specific embodiment, the energy storage battery may be a lithium-ion battery. The battery given voltage of the lithium-ion battery may be 4.2V (this is the maximum voltage when the battery is fully charged, and exceeding this voltage may damage the lithium-ion battery). The voltage threshold may be 4.0V (this is the threshold set by the controller during the charging process).

[0134] Step S1106: When the actual voltage value of the energy storage battery is less than the voltage threshold, a first control signal is generated based on the difference between the actual voltage value and the given voltage of the battery to control the second converter; wherein the first control signal is a control signal for controlling the second converter to output a maximum current and maintain a constant output voltage.

[0135] In this embodiment, the first control signal may be a signal for controlling the output state of the second converter. When the voltage of the energy storage battery is less than a set voltage threshold, the controller generates the control signal to instruct the second converter to charge the energy storage battery with a maximum current while keeping the output voltage constant.

[0136] In this embodiment, the generated action can be represented as the behavior of the controller forming a control signal through a calculation and judgment process according to the difference between the actual voltage value and the given voltage of the battery (voltage error).

[0137] Step S1108: When the actual voltage value of the energy storage battery is equal to or greater than the voltage threshold, generate a second control signal to control the second converter; wherein the second control signal is a control signal for controlling the second converter to reduce the output current and continue to maintain a constant output voltage.

[0138] In this embodiment, the second control signal is a control signal that can instruct the second converter to reduce the output charging current and continue to maintain a constant output voltage when the voltage of the energy storage battery reaches or exceeds the voltage threshold. The core purpose of this signal is to prevent the energy storage battery from overcharging by gradually reducing the charging current when the energy storage battery is close to full, while ensuring that the voltage of the energy storage battery is maintained at a safe constant value.

[0139] In a specific implementation scheme, the photovoltaic energy storage system maintains a constant charging voltage from the beginning to the end of charging, and controls the charging current through a current limiting circuit to ensure that the charging current does not exceed the preset maximum value. In the initial charging stage (low battery voltage), when the battery voltage is lower than the set voltage threshold, the photovoltaic energy storage system charges the energy storage battery with the maximum charging current. At this time, the controller adjusts the PWM signal according to the difference between the battery voltage and the voltage threshold (voltage error) through the PI control algorithm to ensure that the charging current reaches the preset maximum value. As the battery voltage continues to rise, the charging current of the energy storage battery remains at the maximum value until the battery voltage reaches the threshold. In the late charging stage (battery voltage approaches the threshold), when the battery voltage gradually approaches and reaches the voltage threshold, the resistance inside the energy storage battery decreases. At this time, the photovoltaic energy storage system still maintains a constant charging voltage, but the charging current begins to decrease naturally. The charging current of the energy storage battery will gradually decrease as the battery voltage further increases until the energy storage battery is close to fully charged. In the charging completion stage, when the energy storage battery is close to fully charged (the voltage is close to the given voltage of the battery), the charging current of the energy storage battery drops to almost 0. At this time, although the voltage remains constant, the reduction in current ensures that the battery will not be overcharged, thereby protecting the health of the energy storage battery and avoiding overheating.

[0140] Specifically, in this embodiment, the energy storage battery can be a lithium-ion battery. The battery given voltage of the lithium-ion battery can be 4.2V. The voltage threshold can be 4.0V. In the initial charging stage, the initial voltage of the battery can be 3.2V. From the beginning of charging, the charging voltage is kept constant at 4.2V, and the photovoltaic energy storage system outputs the maximum charging current, such as 2A, through the current limiting circuit. When the battery voltage rises to 3.9V, the photovoltaic energy storage system still maintains a constant charging voltage of 4.2V, and the charging current is still close to the maximum value. When the battery voltage reaches 4.0V (voltage threshold), the charging current of the energy storage battery begins to gradually decrease because the impedance inside the energy storage battery gradually decreases. When the battery voltage continues to rise to 4.1V, the photovoltaic energy storage system still maintains a constant charging voltage of 4.2V, but the charging current gradually decreases. Finally, when the energy storage battery approaches 4.2V, the charging current is close to 0A, indicating that the energy storage battery is close to fully charged. At this time, the power gradually decreases, avoiding the risk of overcharging. Therefore, by always maintaining a constant charging voltage and gradually reducing the charging current when the battery voltage approaches the threshold, current mutations (spikes) are effectively avoided, the stability of the charging process is improved, the health of the energy storage battery is protected, and overheating and overcharging of the energy storage battery are avoided, thereby extending the service life of the energy storage battery.

[0141] like Figure 6As shown, in a specific embodiment, the input voltage setting value is Vb*, which is the target voltage of constant voltage charging, which can be a given voltage of the battery (for example, 4.2V). Vb' is the voltage actually measured from the energy storage battery at present. The difference between the two (voltage error) is calculated by comparator K2: Vb*-Vb'. The error signal is transmitted to the PI controller (proportional integral controller) for adjusting the PWM signal output to ensure voltage stability. The PI controller adjusts the output signal according to the voltage error to adjust the actual voltage (Vb') of the energy storage battery to the set value (Vb*) as much as possible. If the voltage error is large, the PI controller will increase the output control signal to ensure that the charging voltage remains within the target voltage range. The role of the PI controller is to smooth the control voltage, avoid voltage overshoot or drop, and ensure stable constant voltage charging. Based on the signal output from the PI controller, the controller can generate a current setting value (I*) as a reference value for the current charging current. I* represents the maximum current reference value adjusted according to the voltage error to ensure that the charging current does not exceed the maximum value in the early stage of charging. The actual battery charging current (I') can be measured in real time by the current sensor and compared with the current reference current value (I*). The difference between the two (current error) can be calculated by the comparator K1: I*-I'. The current error signal is passed to the next PI controller for adjustment. Another PI controller outputs a regulation signal based on the current error and further adjusts the PWM signal to control the charging current. When the actual current of the energy storage battery approaches or exceeds the set maximum charging current, the PI controller reduces the duty cycle of the PWM signal and reduces the current to ensure that the charging process remains within a safe range. Finally, the PWM (pulse width modulation) control signal is sent to the second converter for regulation. The PWM signal adjusts the charging current and voltage by controlling the on-time of the switch. In the early stage of charging (when the voltage is low), the maximum charging current is output; as the battery voltage approaches the set threshold, the charging current gradually decreases until the energy storage battery is nearly fully charged and the current drops to nearly 0A.

[0142] In this embodiment, by adopting a constant voltage and current limiting charging method, the problem of current spikes in the charging method in the related art when the constant current is switched to the constant voltage stage is solved. In this charging method, the controller obtains the actual voltage value of the energy storage battery in real time, determines whether the battery voltage is less than the preset voltage threshold, and generates a corresponding control signal according to the voltage state of the battery, and flexibly adjusts the output current of the second converter. When the battery voltage is low, the controller controls the second converter to output the maximum current charging and keep the voltage constant. When the energy storage battery voltage approaches a given voltage, the controller gradually reduces the output current and continues to maintain a constant output voltage. This method avoids current fluctuations when constant current charging switches to constant voltage charging, thereby effectively preventing the occurrence of current spikes, improving the stability of the photovoltaic energy storage system, and extending the service life of the energy storage battery and other components. At the same time, the current limiting control ensures that the charging current does not exceed the set maximum value, effectively preventing damage to the battery due to overcurrent, and ensuring the safety and efficiency of the entire charging process.

[0143] In some cases, when photovoltaic power generation is not enough to meet the load demand, how to effectively use the electricity in the energy storage battery to power the load is an important technical issue. Especially when the energy storage battery has sufficient power, the photovoltaic energy storage system needs to be able to efficiently convert the energy of the energy storage battery into electricity that meets the load demand through a suitable control strategy. However, in the process of energy storage batteries supplying power to the load, there are problems such as low conversion efficiency, insufficient response speed, and insufficient battery power management in the related art. These problems may lead to unstable power supply of the photovoltaic energy storage system, over-discharge of the energy storage battery, or failure to fully utilize its energy reserves.

[0144] Therefore, if Figure 7 and Figure 8 As shown, in some embodiments, the method may further include:

[0145] Step S112: When the real-time power value of the energy storage battery reaches the power threshold, control the second converter to operate in the third mode so that the energy storage battery supplies power to the load; wherein the third mode is a mode for boosting the output voltage of the energy storage battery to the DC bus voltage.

[0146] In this embodiment, the third mode may be a Boost mode. The second converter may boost the low voltage of the energy storage battery to a high voltage of the DC bus. For example, a 48V battery voltage may be boosted to a 400V DC bus voltage.

[0147] In this implementation, the third mode may also be an LLC resonance mode. The LLC resonance mode achieves efficient power conversion through a resonance circuit, has higher efficiency in the boost process, and can reduce current fluctuations and noise.

[0148] In this embodiment, the third mode may also be a full-bridge conversion mode. The second converter uses a full-bridge topology structure to achieve boosting through multiple switch tubes (for example, IGBTs). This mode can handle higher power and has better control flexibility and efficiency in energy conversion.

[0149] In a specific implementation scheme, a 48V lithium-ion energy storage battery is configured in a household photovoltaic energy storage system for storing electrical energy, and the DC bus voltage of the household photovoltaic energy storage system is 400V. Under normal circumstances, photovoltaic modules (solar panels) power loads in the home, such as lighting, refrigerators, air conditioners, etc. However, at night or on cloudy days, the solar power supply is insufficient, and the system detects that the real-time power of the energy storage battery has reached the set power threshold. The controller triggers the second converter to enter the third mode, that is, the second converter boosts the 48V output voltage of the energy storage battery to a DC bus voltage of 400V. In this mode, the energy storage battery will directly supply the DC bus with the boosted voltage of the second converter, and the DC bus will convert the electrical energy into AC power through the inverter to supply various loads in the home. In this way, even if the solar energy is insufficient, the electrical energy of the energy storage battery can effectively support the work of the load.

[0150] In a specific embodiment, in an industrial photovoltaic energy storage system, the output voltage of the energy storage battery is 100V, the DC bus voltage is set to 600V, and the load may include industrial equipment such as large motors and compressors. These loads require higher voltage and stable power supply. During the day, the photovoltaic module can directly power the industrial equipment, while the excess energy is stored in the energy storage battery. When the photovoltaic power supply is insufficient (such as cloudy days or at night) and the power of the energy storage battery reaches a preset threshold, the controller automatically switches to the third mode. In the third mode, the second converter boosts the 100V voltage of the energy storage battery to a 600V DC bus voltage. This boosting process enables the energy storage battery to match the voltage of the DC bus, thereby powering the industrial load through the inverter.

[0151] This implementation method controls the second converter to operate in the third mode when the power of the energy storage battery reaches the set power threshold, so that the output voltage of the energy storage battery is boosted to the DC bus voltage and supplies power to the load, thereby solving the problem of efficient use of the energy storage battery. In this way, when photovoltaic power generation is insufficient, the energy storage battery can automatically take over the power supply task to ensure that the load obtains a stable power supply. This implementation method also ensures that the output voltage of the energy storage battery is boosted to the DC bus voltage, improving the overall conversion efficiency of the system. The photovoltaic energy storage system can dynamically adjust the mode according to the power of the energy storage battery and the load demand, improve the flexibility and reliability of the power supply, and ensure a stable energy supply under different working conditions.

[0152] In some cases, when the photovoltaic energy storage system always works in the first mode (MPPT mode), the electronic components in the photovoltaic energy storage system will be in a high-power, high-temperature state for a long time, which may cause the components to age faster and reduce the reliability and efficiency of the photovoltaic energy storage system. In addition, continuous high-power operation may increase the electromagnetic interference of the photovoltaic energy storage system, affect the stability of the photovoltaic energy storage system, and even cause overvoltage, overcurrent and other faults and damage the circuit when the monitoring and protection circuits do not respond in time. Therefore, how to enable the photovoltaic energy storage system to operate at a lower power when the load demand is met to avoid unnecessary power loss and component aging is a technical problem that needs to be solved.

[0153] Therefore, if Fig. 9 and Fig.10 As shown, in some embodiments, the method may further include:

[0154] Step S1042: When the output power of the photovoltaic module is greater than or equal to the required power of the load, control the first converter to operate in a fourth mode; wherein the fourth mode is a mode in which the first converter maintains the DC bus voltage at a constant value.

[0155] In this embodiment, the fourth mode may be a constant voltage mode. Specifically, the controller may control the duty cycle of the switch device in the first converter to stabilize the output voltage. The first converter may be a BOOST boost circuit. The BOOST boost circuit may keep the output voltage constant by closed-loop feedback control. More specifically, the voltage sensor detects the output voltage of the BOOST boost circuit in real time and feeds back the detected voltage signal to the controller. The controller compares the detected output voltage with a preset target voltage (e.g., a preset DC bus voltage). In the constant voltage mode, the target voltage is a fixed value. By comparing the output voltage and the target voltage, the error between the two is calculated. The controller adjusts the duty cycle according to the voltage error. If the output voltage is lower than the target voltage, the controller increases the duty cycle of the switch so that the inductor stores more energy, thereby increasing the output voltage; if the output voltage is higher than the target voltage, the controller reduces the duty cycle to reduce the output voltage. The controller outputs a PWM signal to control the switching frequency and duty cycle of the switch device (e.g., MOS tube or IGBT) according to the error adjustment result. The PWM signal adjusts the on and off time of the switch, thereby controlling the boost process of the BOOST circuit. When the duty cycle is adjusted to make the output voltage equal to the target voltage, a balanced state is reached, the output voltage is kept constant, and stable power supply to the load is ensured.

[0156] In a specific implementation scheme, in a household photovoltaic energy storage system, the output power of the photovoltaic module can be 4kW, and the power demand of the household load can be 3kW. In this case, the power generation of the photovoltaic module is greater than the power demand of the household load, which means that the power generation of the photovoltaic module is sufficient to fully meet the load and there is excess energy. In this case, the household photovoltaic energy storage system enters the fourth mode, that is, the first converter is controlled to maintain the DC bus voltage at a constant value, and no longer operates in the first mode (MPPT mode). Because the photovoltaic module can already meet the current load demand, the household photovoltaic energy storage system does not need to continue to pursue maximum power output. Through the fourth mode, the first converter stably boosts the voltage of the photovoltaic module to the DC bus voltage (for example, 400V). Although the photovoltaic module can emit higher power, the household photovoltaic energy storage system only maintains the DC bus voltage constant and ensures that the electrical energy required by the load is met.

[0157] This implementation introduces the fourth mode, that is, when the output power of the photovoltaic module is greater than or equal to the required power of the load, the first converter is controlled to maintain the DC bus voltage at a constant value instead of continuing to work at the maximum power point. This method effectively reduces the high temperature pressure on the components when the photovoltaic energy storage system always works at the maximum power point, reduces unnecessary power loss, and avoids excessive aging of circuit components.

[0158] The fourth mode allows the photovoltaic energy storage system to enter the maximum power point working mode only when necessary (when the photovoltaic power is insufficient). In other cases, by maintaining the DC bus voltage constant, the photovoltaic energy storage system is in a low-power operating state, reducing the heat loss of the components and extending the service life of the photovoltaic energy storage system. In addition, this mode reduces the high current and high-power operating time in the circuit, thereby reducing the risk of electromagnetic interference and improving the stability of the photovoltaic energy storage system.

[0159] In some cases, the power of the photovoltaic energy storage system is greater than or equal to the load demand (that is, the output power of the photovoltaic module is greater than or equal to the required power of the load), and the excess power generated at this time can be used to charge the energy storage battery. However, without an effective monitoring and control strategy, the energy storage battery may be in a state of insufficient power and cannot fully utilize the excess photovoltaic power generation for charging, and may even miss the charging opportunity, resulting in low efficiency and energy waste of the photovoltaic energy storage system. In addition, when the energy storage battery is too low, the photovoltaic power generation is not replenished in time, which may affect the subsequent stability and energy storage capacity of the photovoltaic energy storage system.

[0160] Therefore, in some embodiments, the method may further include:

[0161] Step S1044: When the output power of the photovoltaic module is greater than or equal to the required power of the load, the real-time power value of the energy storage battery is obtained.

[0162] In this embodiment, the acquisition action can be expressed as an action of the controller to collect data on the real-time power value of the energy storage battery. Specifically, the controller can be communicatively connected to the battery management system (BMS) of the energy storage battery. The controller can send a data acquisition request to the battery management system of the energy storage battery. For example, the controller can send a data request to the battery management system through a communication interface (for example, CAN, RS485, etc.). The data acquisition request is a request for obtaining the real-time power value of the energy storage battery. It can be understood that a variety of methods can be preset in the battery management system to calculate the state of charge (SOC) of the energy storage battery, that is, the real-time power value. The multiple methods can be a current integration method or an open circuit voltage method, etc. The battery management system can send the real-time power value of the energy storage battery to the controller based on the data acquisition request.

[0163] In some embodiments, when the energy storage battery is not equipped with a battery management system, the acquisition action may be that the controller measures the terminal voltage of the energy storage battery through a voltage sensor, and estimates the SOC in combination with the characteristic curve of the voltage and SOC of the energy storage battery. It is understandable that the characteristic curve of the voltage and SOC of the energy storage battery may be preset in the controller. Therefore, after obtaining the terminal voltage of the energy storage battery, the measured terminal voltage may be matched with the characteristic curve of the voltage and SOC to obtain the real-time power value of the energy storage battery.

[0164] Step S1046: Determine whether the real-time power value of the energy storage battery is less than the power threshold.

[0165] Step S1048: When the real-time power value of the energy storage battery is less than the power threshold, control the second converter to operate in the second mode so that the photovoltaic module charges the energy storage battery.

[0166] This implementation method obtains the power value of the energy storage battery in real time and dynamically adjusts the charging strategy according to its power state, ensuring that the photovoltaic energy storage system can fully utilize the photovoltaic power to charge the energy storage battery when the power is greater than or equal to the load demand. By monitoring the power state of the energy storage battery, the actual power value of the energy storage battery can be obtained in real time when the output power of the photovoltaic module is greater than or equal to the required power of the load. This ensures that the photovoltaic energy storage system can keep track of the current power level of the energy storage battery. In the case of insufficient power, the system controls the second converter to enter the second mode (step-down mode), so that the photovoltaic module can use the excess power generation to charge the energy storage battery. This method can ensure that excess photovoltaic power is not wasted, but is effectively stored in the energy storage battery for subsequent use.

[0167] In some cases, when the energy storage battery in the photovoltaic energy storage system reaches or exceeds the preset power threshold, if there is no effective management strategy, the photovoltaic energy storage system may continue to charge the energy storage battery. This will not only cause battery overcharging, increase battery loss and aging risks, but may also cause safety issues such as overvoltage and overheating. In addition, overcharged energy storage batteries may affect the overall efficiency of the photovoltaic energy storage system, resulting in the excess photovoltaic power not being reasonably utilized. Therefore, how to stop charging in time when the energy storage battery power reaches or exceeds the set threshold to avoid battery overcharging and system loss is a technical problem that needs to be solved.

[0168] Therefore, in some embodiments, the method further comprises:

[0169] Step S10410: When the real-time power value of the energy storage battery is greater than or equal to the power threshold, control the second converter to disconnect.

[0170] This implementation automatically controls the second converter to disconnect the charging path when the power of the energy storage battery reaches or exceeds a preset power threshold, ensuring that the photovoltaic energy storage system stops further charging the energy storage battery, thereby solving the problem of possible overcharging of the energy storage battery and ensuring the safety and efficiency of the operation of the photovoltaic energy storage system.

[0171] like Fig.11 As shown, according to an embodiment of the present invention, a control device for a photovoltaic energy storage system is provided, wherein the photovoltaic energy storage system comprises a photovoltaic module and a load electrically connected thereto; the device comprises:

[0172] A determination module, which is used to determine the output power of the photovoltaic module and the required power of the load;

[0173] A control module, which is used to control the first converter to operate in a first mode when the output power of the photovoltaic module is less than the required power of the load; wherein the first converter is a converter for performing a voltage boost processing on the output voltage of the photovoltaic module; and the first mode is a mode in which the first converter causes the photovoltaic module to operate at a maximum power point.

[0174] According to an embodiment of the present invention, an electronic device is provided. Fig.12 The electronic device in this embodiment may include one or more of the following components: a processor, a network interface, a memory, a non-volatile memory, and one or more applications, wherein the one or more applications may be stored in the non-volatile memory and configured to be executed by one or more processors, and the one or more programs are configured to execute the method described in the aforementioned method embodiment.

[0175] According to an embodiment of the present invention, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a computer, the computer executes the method described in any of the above embodiments.

[0176] According to an embodiment of the present invention, a computer program product including instructions is also provided. When the instructions are executed by a computer, the computer executes a method in any one of the above embodiments.

[0177] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0178] Optionally, the specific examples in this embodiment may refer to the examples described in the above embodiments, and this embodiment will not be described in detail here.

[0179] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0180] In the above embodiments of the present application, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0181] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A photovoltaic energy storage system, comprising a photovoltaic module and an energy storage battery, characterized in that: Also includes: A first converter, whose input end is connected to the photovoltaic module and whose output end is connected to the load via a DC bus; wherein the first converter is a converter for performing a voltage boost process on the output voltage of the photovoltaic module; A second converter, wherein a first input / output terminal of the second converter is connected to the energy storage battery, and a second input / output terminal of the second converter is connected in parallel to the DC bus together with the first converter; wherein the second converter is a converter capable of boosting the output voltage of the energy storage battery to the DC bus voltage, or stepping down the DC bus voltage to a voltage suitable for the energy storage battery input; The controller is respectively connected to the photovoltaic module, the first converter and the second converter, and is used to control the photovoltaic module to operate in the first mode only when the output power of the photovoltaic module is less than the power required by the load; wherein the first mode is a mode in which the first converter makes the photovoltaic module operate at the maximum power point.

2. A control method for a photovoltaic energy storage system, characterized in that: The photovoltaic energy storage system includes a photovoltaic module and an energy storage battery, and the method includes: Determine the output power of the photovoltaic module and the required power of the load; When the output power of the photovoltaic module is less than the required power of the load, the first converter is controlled to operate in a first mode; wherein the first converter is a converter for performing a voltage boost processing on the output voltage of the photovoltaic module; the first mode is a mode in which the first converter causes the photovoltaic module to operate at a maximum power point.

3. The method according to claim 2, characterized in that The method further comprises: When the output power of the photovoltaic module is less than the required power of the load, obtaining the real-time power value of the energy storage battery; Determine whether the real-time power value of the energy storage battery is less than a power threshold; When the real-time power value of the energy storage battery is less than the power threshold, the second converter is controlled to operate in the second mode so that the photovoltaic module charges the energy storage battery; wherein the second converter is a converter capable of boosting the output voltage of the energy storage battery to a DC bus voltage, or stepping down the DC bus voltage to a voltage suitable for the energy storage battery input; the second mode is a mode in which the second converter steps down the DC bus voltage to a voltage suitable for the energy storage battery input.

4. The method according to claim 3, characterized in that The step of controlling the second converter to operate in the second mode comprises: During the charging process of the energy storage battery, obtaining the actual voltage value of the energy storage battery; Determine whether the actual voltage value of the energy storage battery is less than a voltage threshold; wherein the voltage threshold is a voltage value less than a given voltage of the battery; When the actual voltage value of the energy storage battery is less than the voltage threshold, a first control signal is generated based on the difference between the actual voltage value and the given voltage of the battery to control the second converter; wherein the first control signal is a control signal for controlling the second converter to output a maximum current and maintain a constant output voltage; When the actual voltage value of the energy storage battery is equal to or greater than the voltage threshold, a second control signal is generated to control the second converter; wherein the second control signal is a control signal for controlling the second converter to reduce the output current and continue to maintain a constant output voltage.

5. The method according to claim 3, characterized in that: The method further comprises: When the real-time power value of the energy storage battery is equal to or greater than the power threshold, the second converter is controlled to operate in a third mode so that the energy storage battery supplies power to the load; wherein the third mode is a mode for boosting the output voltage of the energy storage battery to a DC bus voltage.

6. The method according to claim 3, characterized in that The method further comprises: When the output power of the photovoltaic module is greater than or equal to the required power of the load, the first converter is controlled to operate in a fourth mode; wherein the fourth mode is a mode in which the first converter maintains the DC bus voltage at a constant value.

7. The method according to claim 6, characterized in that The method further comprises: When the output power of the photovoltaic module is greater than or equal to the required power of the load, obtaining the real-time power value of the energy storage battery; Determine whether the real-time power value of the energy storage battery is less than a power threshold; When the real-time power value of the energy storage battery is less than the power threshold, the second converter is controlled to operate in the second mode, so that the photovoltaic module charges the energy storage battery.

8. The method according to claim 7, characterized in that The method further comprises: When the real-time power value of the energy storage battery is greater than or equal to the power threshold, the second converter is controlled to be disconnected.

9. A control device for a photovoltaic energy storage system, characterized in that: The photovoltaic energy storage system includes a photovoltaic module and an energy storage battery; the device includes: A determination module, which is used to determine the output power of the photovoltaic module and the required power of the load; A control module, which is used to control the first converter to operate in a first mode when the output power of the photovoltaic module is less than the required power of the load; wherein the first converter is a converter for performing a boost processing on the output voltage of the photovoltaic module; and the first mode is a mode in which the first converter causes the photovoltaic module to operate at a maximum power point.

10. An electronic device, characterized in that: include: a memory, and one or more processors communicatively coupled to the memory; Instructions executable by the one or more processors are stored in the memory. The instructions are executed by the one or more processors to enable the one or more processors to implement the method according to any one of claims 2 to 8.

11. A computer-readable storage medium, characterized in that: The readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 2 to 8 is implemented.

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