Photovoltaic power generation system and control method of photovoltaic power generation system

Abstract

The invention discloses a photovoltaic power generation system and a control method of the photovoltaic power generation system, and relates to the technical field of photovoltaic power generation, and the photovoltaic power generation system comprises a photovoltaic module which is configured to convert solar energy into electric energy; a direct current bus configured to; transmitting the electric energy to the electric energy absorption equipment; the controller is configured to obtain the bus voltage of the direct current bus; determining a first working mode corresponding to the bus voltage based on a plurality of preset bus voltage intervals; each bus voltage interval corresponds to one working mode; the working mode is divided into a first mode for maintaining voltage stabilization control of the bus voltage, a second mode for limiting the amplitude of the bus voltage, and a third mode for disconnecting the photovoltaic module from transmitting power to the direct current bus; and operating a first working mode corresponding to the first working interval, and controlling power transmission or disconnection of the photovoltaic module to the direct current bus. By adopting the method, instant suppression of bus voltage fluctuation can be realized, and stable operation of the direct-current bus is ensured.

Description

Technical Field

[0001] This application relates to the field of photovoltaic power generation technology, and in particular to a photovoltaic power generation system and a control method for the photovoltaic power generation system. Background Technology

[0002] The function of a photovoltaic (PV) power generation system is to convert solar energy into direct current (DC) through PV modules and then efficiently transmit it to energy storage devices, electrical loads, and other energy consumption terminals via a DC bus. In actual operation, the DC bus voltage of a PV power generation system is susceptible to interference from multiple dynamic factors: on the PV side, sudden changes in irradiance and temperature fluctuations can cause rapid increases and decreases in PV output power, directly altering the input energy to the bus; on the load side, the start-up and shutdown of electrical equipment and the switching of energy storage charging and discharging states can trigger sudden changes in energy consumption, causing bus voltage fluctuations; under extreme conditions (such as a sudden shift from cloudy to sunny weather or a sudden disconnection of the load), the bus voltage may rapidly exceed the overvoltage threshold, or drop to the undervoltage threshold when PV power suddenly decreases or the load suddenly increases, affecting system stability.

[0003] In existing technologies, the stable control of DC bus voltage mainly relies on the active adaptation and adjustment of the energy absorption end (equipment on the load side). For example, when the bus voltage is too high, the charging power of the energy storage device is increased to absorb excess energy; when it is too low, it switches to discharge mode to replenish energy. The electrical load adjusts its input power through its own converter, such as starting standby loads to consume energy when the bus is overvoltaged and reducing unnecessary load power when it is undervoltaged. At the same time, the energy absorption end can feed back real-time bus voltage information to the photovoltaic power generation system. The photovoltaic power generation system only passively adjusts its output power based on this feedback, forming a control mode in which the absorption end is dominant and the photovoltaic end follows.

[0004] However, relying on the dominant voltage adaptation at the power consumption end, when the bus voltage approaches the overvoltage threshold, the photovoltaic power generation system lacks the ability to assist the power consumption end in suppressing voltage rise, thus increasing the regulation burden on the power consumption end. Furthermore, when relying on feedback from the power consumption end for power regulation, the photovoltaic power generation system cannot quickly block energy transmission to the bus, easily leading to instantaneous overvoltage / undervoltage surges to components such as the DC bus capacitor and power converter, posing a risk of equipment damage. Summary of the Invention

[0005] This application provides a photovoltaic power generation system and a control method for the photovoltaic power generation system, which can solve the problem that the increased regulation burden at the power consumption end can easily lead to equipment damage in the photovoltaic power generation system.

[0006] In a first aspect, a photovoltaic power generation system is provided, comprising: Photovoltaic modules are configured to convert solar energy into electrical energy; The DC bus connected to the photovoltaic modules is configured to receive electrical energy transmitted by the photovoltaic modules and transmit the electrical energy to the power consumption equipment. The controller is configured as follows: Obtain the bus voltage of the DC bus; Based on multiple preset bus voltage ranges, a first operating mode corresponding to the bus voltage is determined; each bus voltage range corresponds to one operating mode; the operating modes are divided into a first mode for maintaining bus voltage regulation and control, a second mode for assisting the first mode in limiting the bus voltage, and a third mode for disconnecting the photovoltaic modules from transmitting power to the DC bus. Run the first working mode corresponding to the first working zone to control the power transmission of the photovoltaic modules to the DC bus or disconnect it.

[0007] In the aforementioned technical solution, the controller acquires the DC bus voltage in real time and determines the first operating mode based on multiple bus voltage ranges. This allows the photovoltaic power generation system to proactively switch operating modes according to the actual state of the bus voltage, changing the control logic in related technologies where the photovoltaic end passively follows feedback from the power consumption end. It enables direct response to bus voltage fluctuations from the energy input side, improving the system's response speed to bus voltage changes. Furthermore, in the first mode, the controller can independently maintain bus voltage stabilization control, ensuring efficient power output from the photovoltaic modules. In the second mode, it assists the first mode in limiting the output, suppressing bus voltage increases by appropriately reducing power output, avoiding overvoltage risks from high power output or energy waste from simply cutting off power, thus reducing the regulation burden on the power consumption end. In the third mode, it quickly disconnects the power transmission from the photovoltaic modules to the DC bus. Compared to the hysteresis protection of related technologies, this more promptly avoids damage to devices from instantaneous voltage surges, improving equipment safety. Moreover, the clear correspondence between bus voltage ranges and operating modes clarifies the bus voltage's operating mode, reducing operational oscillations and ensuring the long-term reliability of the system. Based on the acquired bus voltage, the controller can ensure that the photovoltaic power generation system can track changes in bus voltage in real time and dynamically adjust the control logic. This can solve the problem of response lag in traditional passive control, achieve immediate suppression of bus voltage fluctuations, and ensure stable operation of the DC bus.

[0008] Secondly, a control method for a photovoltaic power generation system is provided, applied to the photovoltaic power generation system, including photovoltaic modules configured to convert solar energy into electrical energy; a DC bus connected to the photovoltaic modules configured to receive electrical energy transmitted by the photovoltaic modules and transmit the electrical energy to power consumption equipment; the method includes: Obtain the bus voltage of the DC bus; Based on multiple preset bus voltage ranges, a first operating mode corresponding to the bus voltage is determined; each bus voltage range corresponds to one operating mode; the operating modes are divided into a first mode for maintaining bus voltage regulation and control, a second mode for assisting the first mode in limiting the bus voltage, and a third mode for disconnecting the photovoltaic modules from transmitting power to the DC bus. Run the first working mode corresponding to the first working zone to control the power transmission of the photovoltaic modules to the DC bus or disconnect it.

[0009] Thirdly, a computer-readable storage medium is provided, which stores a computer program that, when run by a photovoltaic power generation system, causes the photovoltaic power generation system to execute the control method of the photovoltaic power generation system in the second aspect.

[0010] Fourthly, a computer program product is provided, comprising: a computer program that, when run by a photovoltaic power generation system, causes the photovoltaic power generation system to execute the control method of the photovoltaic power generation system in the second aspect.

[0011] It is understood that the beneficial effects of the second to fourth aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0012] Figure 1 This is a schematic diagram illustrating application scenarios of photovoltaic power generation systems in related technologies; Figure 2 This is a timing interaction diagram of a control method for a photovoltaic power generation system provided in the embodiments of this application; Figure 3 This is a schematic diagram showing the relationship between the bus voltage range and the operating mode in a control method for a photovoltaic power generation system provided in an embodiment of this application; Figure 4 This is a schematic diagram of the working mode switching in a control method for a photovoltaic power generation system provided in an embodiment of this application; Figure 5 This is a flowchart illustrating the first operating mode of a control method for a photovoltaic power generation system provided in an embodiment of this application; Figure 6 This is a flowchart illustrating the first operating mode of a control method for a photovoltaic power generation system provided in another embodiment of this application; Figure 7 This is a schematic flowchart of the second operating mode in a control method for a photovoltaic power generation system provided in an embodiment of this application; Figure 8 This is a flowchart illustrating the second mode of operation in a control method for a photovoltaic power generation system provided in another embodiment of this application; Figure 9 This is a schematic diagram of the first and second modes of a control method for a photovoltaic power generation system provided in an embodiment of this application; Figure 10 This is a control diagram of the first and second modes in a control method for a photovoltaic power generation system provided in another embodiment of this application; Figure 11 This is a schematic diagram of the first and second modes of a control method for a photovoltaic power generation system provided in one embodiment of this application. Detailed Implementation

[0013] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B; "and / or" in this text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more than two.

[0014] Hereinafter, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature.

[0015] Specific details, such as particular system architectures and techniques, are set forth for illustrative purposes and not for limitation, to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted to avoid unnecessary detail that could obscure the description of this application.

[0016] The function of a photovoltaic (PV) power generation system is to convert solar energy into direct current (DC) through PV modules and then efficiently transmit it to energy storage devices, electrical loads, and other energy consumption terminals via a DC bus. In actual operation, the DC bus voltage of a PV power generation system is susceptible to interference from multiple dynamic factors: on the PV side, sudden changes in irradiance and temperature fluctuations can cause rapid increases and decreases in PV output power, directly altering the input energy to the bus; on the load side, the start-up and shutdown of electrical equipment and the switching of energy storage charging and discharging states can trigger sudden changes in energy consumption, causing bus voltage fluctuations; under extreme conditions (such as a sudden shift from cloudy to sunny weather or a sudden disconnection of the load), the bus voltage may rapidly exceed the overvoltage threshold, or drop to the undervoltage threshold when PV power suddenly decreases or the load suddenly increases, affecting system stability.

[0017] For example, refer to Figure 1 , Figure 1This is a schematic diagram illustrating the application scenario of a photovoltaic (PV) power generation system in related technologies. The PV system includes PV modules, which act as an energy source, converting solar energy into direct current (DC), serving as the system's starting point for electrical energy input. A DC-DC converter (DC converter) connects its input to the PV modules and its output to the DC bus. The DC converter can control the power transfer from the PV modules to the DC bus by adjusting the on / off state of the power switching transistors (e.g., PWM control). The DC bus is the power hub of the PV system, responsible for collecting the electrical energy transmitted from the PV side and distributing it to downstream equipment (power consumption equipment). The controller, connected via dashed lines (signal flow), is linked to each power converter (PV-side DC-DC, grid-side AC-DC, energy storage-side DC-DC, etc.) and is responsible for collecting signals such as the DC bus voltage and PV output, calculating and outputting control commands (e.g., PWM signals) to achieve coordinated control of each converter, thereby completing functions such as PV power regulation, bus voltage stabilization control, energy storage charging and discharging management, and grid connection control.

[0018] An AC-DC converter connects to the DC bus at its input and to the power grid at its output. Its function is to convert the DC power into AC power, enabling the grid-connected transmission of photovoltaic power.

[0019] The DC-DC converter on the energy storage side connects to the DC bus at its input and to the energy storage device at its output. It is used to control the charging and discharging process of the energy storage device (storing the bus's electrical energy during charging and feeding back electrical energy to the bus during discharging).

[0020] like Figure 1 As shown, in Figure 1 In the photovoltaic power generation system architecture shown, the photovoltaic modules convert solar energy into direct current, which is then connected to the DC bus via a DC-DC converter. The DC bus serves as the power hub, enabling grid connection of power through an AC-DC converter and energy interaction with the energy storage battery via a DC-DC converter on the energy storage side. The controller then coordinates and regulates each power conversion unit through a signal link.

[0021] During actual system operation, if the system enters a power-limited operation state due to grid dispatch requirements, battery capacity limitations, or other factors, the charging and discharging power of the energy storage battery or the grid-connected power of the AC-DC converter will be forcibly reduced. At this time, the electrical energy output by the photovoltaic modules cannot be absorbed in time, and excess energy will continuously accumulate at the DC bus, causing the bus voltage to rise continuously. Once the bus voltage exceeds the overvoltage threshold set by the photovoltaic power generation system, the protection mechanism will be triggered, leading to a photovoltaic power generation system failure, severely affecting the stable operation and continuous power generation capacity of the photovoltaic power generation system.

[0022] In related technologies, the stable control of DC bus voltage mainly relies on the active adaptation and adjustment of the energy absorption end. For example, when the bus voltage is too high, the charging power of the energy storage device is increased to absorb excess energy; when it is too low, it switches to the discharge mode to replenish energy. The electrical load adjusts its input power through its own converter, such as starting standby loads to consume energy when the bus is overvoltaged, and reducing the power of unnecessary loads when the bus is undervoltaged. At the same time, the energy absorption end can feed back real-time bus voltage information to the photovoltaic power generation system. The photovoltaic power generation system only passively adjusts its output power based on this feedback, forming a control mode in which the absorption end is dominant and the photovoltaic end follows.

[0023] However, relying on the dominant voltage adaptation at the power consumption end, when the bus voltage approaches the overvoltage threshold, the photovoltaic power generation system lacks the ability to assist the power consumption end in suppressing voltage rise, thus increasing the regulation burden on the power consumption end. Furthermore, when relying on feedback from the power consumption end for power regulation, the photovoltaic power generation system cannot quickly block energy transmission to the bus, easily leading to instantaneous overvoltage / undervoltage surges to components such as the DC bus capacitor and power converter, posing a risk of equipment damage.

[0024] Therefore, in order to solve the problem of response lag in traditional passive control and to achieve real-time suppression of bus voltage fluctuations through cyclic feedback to ensure stable operation of the DC bus, please refer to [link to relevant documentation]. Figure 2 , Figure 2 This is a timing interaction diagram of a control method for a photovoltaic power generation system provided in the embodiments of this application, such as... Figure 2 As shown, a photovoltaic power generation system includes: photovoltaic modules configured to convert solar energy into electrical energy; a DC bus connected to the photovoltaic modules configured to receive the electrical energy transmitted by the photovoltaic modules and transmit the electrical energy to an energy consumption device; and a controller configured to perform the following steps: S201. Obtain the bus voltage of the DC bus.

[0025] In one embodiment, the photovoltaic module is a power generation unit composed of multiple photovoltaic cells connected in series or parallel, which can directly convert solar energy into direct current through the photovoltaic effect. The output power of the photovoltaic module is affected by factors such as light intensity and ambient temperature, and requires control strategies to achieve efficient power output.

[0026] A DC bus is a DC power transmission channel composed of conductive busbars or cables, and is the energy hub of the system. One end is connected to the photovoltaic modules (usually via a DC converter) to receive the DC power output from the photovoltaic modules; the other end is connected to the power consumption equipment, which is responsible for distributing the collected power to each consumption end, realizing centralized transmission and allocation of energy.

[0027] The aforementioned power consumption equipment refers to devices that consume or store the electrical energy output from photovoltaic modules, such as... Figure 1As shown, these include, but are not limited to, energy storage batteries (which store electrical energy through charging and discharging), DC loads (devices that directly use DC power), and AC inverters (which convert DC power into AC power for use by AC loads or grid connection). Their function is to absorb the electrical energy generated by photovoltaics and maintain the energy balance of the system.

[0028] The bus voltage mentioned above refers to the DC voltage value on the DC bus. Maintaining the bus voltage within a reasonable range (such as near the rated voltage of the equipment) is fundamental to the safe operation of a photovoltaic power generation system. Excessive bus voltage may damage capacitors, switching transistors, and other components, while insufficient bus voltage can lead to insufficient power supply to the load or abnormal charging and discharging of energy storage.

[0029] The controller can detect the DC bus voltage signal in real time through voltage acquisition modules (such as Hall voltage sensors and precision voltage divider resistor networks), convert the analog voltage signal into a digital signal that the controller can recognize, and then transmit it to the controller's computing unit to provide a basis for subsequent working mode determination and power control.

[0030] In another embodiment, the bus voltage can also be collected by a power consumption device connected to the bus voltage and then transmitted to the controller in the photovoltaic power generation system through a preset communication protocol, without limitation.

[0031] S202. Based on multiple preset bus voltage ranges, determine the first operating mode corresponding to the bus voltage.

[0032] Each bus voltage range corresponds to a working mode; the working modes are divided into a first mode for maintaining bus voltage regulation and control, a second mode for assisting the first mode in limiting the bus voltage, and a third mode for disconnecting the photovoltaic modules from transmitting power to the DC bus.

[0033] It is understandable that, since the second mode assists the first mode in limiting the bus voltage, it can be assumed that the first mode must be running when the second mode is operating. However, if the first mode can maintain bus voltage regulation on its own without the assistance of the second mode for limiting, the first mode can operate independently. Furthermore, since the third mode will disconnect the path for power transmission from the photovoltaic modules to the DC bus, it can be assumed that the first and second modes do not need to operate when the third mode is running.

[0034] In one embodiment, the bus voltage range is a set of multiple DC bus voltage ranges preset according to system safety operation requirements, equipment rated parameters, and control objectives. These ranges are divided by key critical values ​​(such as bus overvoltage threshold, bus high voltage threshold, overvoltage recovery threshold, undervoltage recovery threshold, undervoltage threshold, etc.) to define control strategies under different voltage conditions. For example, they may include normal stable range, critical overvoltage range, extreme overvoltage / undervoltage range, etc., with each range corresponding to a specific operating mode to ensure that the voltage can be accurately controlled under different conditions.

[0035] The first operating mode is the specific control mode that the controller ultimately determines based on the current bus voltage range, which is the corresponding mode matched from the first mode, the second mode, and the third mode, to achieve a precise mapping between voltage state and control mode.

[0036] The first mode is an independent control mode suitable for bus voltages within a normal stable range (e.g., between the undervoltage recovery threshold and the overvoltage recovery threshold). In this mode, the controller operates independently using only the photovoltaic-side control algorithm (e.g., the disturbance observation method). While maximizing the output power of the photovoltaic modules, it maintains stable bus voltage control by adjusting the photovoltaic output voltage / current, without the need for assistance from other modes. This mode is used to balance efficient power output with stable voltage.

[0037] The second mode is a coordinated control mode suitable for bus voltages in the critical overvoltage range (e.g., between the bus high voltage threshold and the bus overvoltage threshold). This mode is based on the first mode but adds a limiting regulation function. For example, by calculating the difference between the bus voltage and the high voltage threshold, a negative control signal is generated and superimposed on the power regulation signal of the first mode to moderately reduce photovoltaic output power and suppress further increases in bus voltage. Its function is to assist the first mode in limiting voltage, reduce the voltage regulation burden on power consumption equipment (such as energy storage and converters), and prevent the voltage from exceeding the overvoltage threshold. Therefore, the first mode can also operate within the range where the second mode operates.

[0038] The third mode is a safety protection mode applicable when the bus voltage is in an extreme overvoltage / undervoltage range (such as above the bus overvoltage threshold or below the bus undervoltage threshold). In this mode, the controller can directly cut off the power transmission from the photovoltaic modules to the DC bus. The goal is to quickly isolate the photovoltaic energy input, prevent extreme voltage surges from damaging components such as bus capacitors and power switches, and ensure the safety of the system hardware.

[0039] It should be noted that the controller can preset multiple bus voltage ranges (defined by critical values) and bind a corresponding mode (first mode, second mode, and third mode) to each range. After acquiring the bus voltage in real time, it can determine which preset range it belongs to, and then determine the first operating mode to be run. Finally, it executes the control logic of the mode (independent voltage regulation in the first mode, collaborative limiting in the second mode, and power disconnection in the third mode) to realize the dynamic adaptation of the photovoltaic system to changes in bus voltage, taking into account both efficiency and safety.

[0040] As an example, the controller can determine the first operating mode according to the following steps, detailed below: If the bus voltage is greater than or equal to the preset bus overvoltage threshold, or less than or equal to the preset bus undervoltage threshold, then the first working mode is determined to be the third mode. If the bus voltage is greater than or equal to the preset bus high voltage threshold and less than the bus overvoltage threshold, then the first working mode is determined to be the second mode. If the bus voltage is greater than or equal to the preset undervoltage recovery threshold and less than the bus overvoltage threshold, then the first operating mode is determined to be the first mode; the undervoltage recovery threshold is greater than the bus undervoltage threshold, and the bus overvoltage is greater than the bus high voltage threshold.

[0041] Among them, the bus overvoltage threshold, bus undervoltage threshold, bus high voltage threshold, bus overvoltage threshold, undervoltage recovery threshold, and overvoltage recovery threshold can all be set according to the actual situation, and there are no restrictions on them.

[0042] Specifically, the bus overvoltage threshold can be equal to the bus capacitor rated voltage - 50V. The bus high voltage threshold can be equal to the standard bus voltage + 100V. The overvoltage recovery threshold can be equal to the standard bus voltage + 80V. The undervoltage recovery threshold can be equal to the standard bus voltage - 80V. The bus undervoltage threshold can be equal to the standard bus voltage - 200V.

[0043] The rated voltage of the bus capacitor refers to the maximum DC voltage value at which the energy storage capacitor (such as an electrolytic capacitor) in the DC bus can operate safely for a long period of time. It is an inherent performance parameter of the capacitor, determined by its materials and manufacturing process. If the operating voltage exceeds this value for a long period of time, the capacitor may experience insulation breakdown, a sharp reduction in lifespan, or even thermal runaway due to overvoltage.

[0044] The standard bus voltage is the normal operating voltage of the DC bus specified in the design of the photovoltaic energy storage system. It serves as the voltage reference for the coordinated operation of various devices (DC-DC converters, energy storage batteries, inverters, etc.) within the system, ensuring the matching of equipment parameters and the unification of control logic.

[0045] It should be noted that under extreme operating conditions (greater than or equal to the preset bus overvoltage threshold, or less than or equal to the preset bus undervoltage threshold): the third mode is triggered, directly disconnecting the photovoltaic power transmission, quickly isolating dangerous voltages, and protecting devices such as bus capacitors and power switching transistors.

[0046] The second mode is triggered when the critical operating condition (greater than or equal to the preset high voltage threshold of the bus and less than the overvoltage threshold of the bus) is reached. This can be achieved by early intervention through coordinated limiting before the bus voltage reaches an extreme dangerous value (e.g., the overvoltage threshold of the bus), thereby reducing the voltage stabilization burden on the power consumption equipment and preventing the operating condition from deteriorating.

[0047] Under normal operating conditions (greater than or equal to the preset undervoltage recovery threshold and less than the overvoltage recovery threshold), the first mode allows the controller to focus on basic DC bus voltage regulation, balancing power efficiency and voltage stability. Furthermore, since a second mode can be triggered under critical conditions, and the function of the second mode is to limit the bus voltage during the first mode operation, the first mode also needs to be run under critical conditions. That is, the first mode must be run within the range where the bus voltage is greater than or equal to the preset undervoltage recovery threshold and less than the bus overvoltage threshold.

[0048] Furthermore, the undervoltage recovery threshold is greater than the bus undervoltage threshold, while the overvoltage recovery threshold is less than the bus high-voltage threshold. Therefore, on the overvoltage side, there is a difference between the bus high-voltage threshold and the overvoltage recovery threshold; similarly, on the undervoltage side, there is also a difference between the undervoltage recovery threshold and the bus undervoltage threshold. This hysteresis design prevents frequent switching (jittering) of the operating mode when the bus voltage is near the critical value, thereby reducing control oscillations and improving system stability.

[0049] It should be noted that in this embodiment, by setting bus overvoltage threshold, bus undervoltage threshold, bus high voltage threshold, undervoltage recovery threshold, and overvoltage recovery threshold, and by clearly defining the judgment rules for extreme voltage (≥ bus overvoltage threshold or ≤ bus undervoltage threshold) corresponding to the third mode, critical overvoltage (≥ bus high voltage threshold < bus overvoltage threshold) corresponding to the second mode, and normal voltage and overvoltage (≥ undervoltage recovery threshold and < bus overvoltage threshold) corresponding to the first mode, not only can precise graded adaptation to different voltage conditions be achieved, but also frequent mode switching of bus voltage near critical values ​​can be effectively avoided, ensuring that all voltage scenarios have a clear and unique control strategy. That is, in extreme conditions, power is quickly disconnected to ensure equipment safety; in critical conditions, voltage is limited to suppress voltage deterioration; and in normal conditions, efficient output is achieved while taking into account voltage stabilization and energy efficiency, significantly improving the voltage control accuracy, operational stability, and equipment safety of the photovoltaic power generation system.

[0050] As an example, the rated voltage of the bus capacitor is 1000V (standard specification for industrial-grade high-voltage DC bus capacitors, with sufficient withstand voltage redundancy, suitable for medium and high power photovoltaic energy storage systems), and the standard bus voltage is 750V (common reference voltage for high-voltage DC buses in photovoltaic power generation systems, balancing power transmission efficiency and equipment compatibility). The critical values ​​are as follows: Bus overvoltage threshold = Bus capacitor rated voltage - 50V = 1000V - 50V = 950V; Busbar high voltage threshold = standard busbar voltage + 100V = 750V + 100V = 850V; Overvoltage recovery threshold = standard bus voltage + 80V = 750V + 80V = 830V; Undervoltage recovery threshold = Standard bus voltage - 80V = 750V - 80V = 670V; Bus undervoltage threshold = standard bus voltage - 200V = 750V - 200V = 550V.

[0051] It should be noted that, as explained above, there is a certain hysteresis range between the overvoltage recovery threshold and the main high-voltage threshold, and between the bus undervoltage threshold and the undervoltage recovery threshold. (Refer to...) Figure 2 As shown, there is a hysteresis interval one between the overvoltage recovery threshold and the main high-voltage threshold, and a hysteresis interval two between the bus undervoltage threshold and the undervoltage recovery threshold. Within each hysteresis interval, the controller can determine the first operating mode according to the following steps, detailed below: If the bus voltage is greater than or equal to the overvoltage recovery threshold and less than the bus high voltage threshold, or if the bus voltage is greater than the bus undervoltage threshold and less than the undervoltage recovery threshold, then the second operating mode of the photovoltaic power generation system in the previous operation is obtained. The second working mode is designated as the first working mode.

[0052] In one embodiment, the second operating mode is not a new mode type independent of the first, second, and third modes, but rather the operating mode executed during the previous operation of the photovoltaic power generation system (i.e., the first operating mode determined in the previous round). Essentially, it is the historical operating mode state stored by the controller. Its function is to work with the hysteresis interval (overvoltage recovery threshold - bus high voltage threshold, bus undervoltage threshold - undervoltage recovery threshold) to achieve anti-jitter control, avoiding frequent switching of the system operating mode (such as repeatedly jumping between the first and second modes) when the bus voltage fluctuates slightly near the critical value.

[0053] For example, if the photovoltaic power generation system previously operated in the second mode due to the bus voltage ≥ 850V (bus high voltage threshold), and the voltage subsequently drops to 840V (between the overvoltage recovery threshold of 830V and the high voltage threshold of 850V), then the second operating mode includes the previous second mode, and the photovoltaic power generation system can continue to maintain this mode instead of only operating in the first mode.

[0054] Furthermore, if the photovoltaic power generation system previously operated in the third mode due to a bus voltage below 550V (the bus undervoltage threshold), and subsequently the bus voltage gradually increases to 600V (between the bus undervoltage threshold of 550V and the undervoltage recovery threshold of 670V), then the second operating mode includes the previous third mode. The photovoltaic power generation system can still maintain the third mode instead of operating in the first mode. Similarly, if the photovoltaic power generation system previously operated in the first mode due to a bus voltage of 700V (located between the undervoltage recovery threshold of 670V and the overvoltage recovery threshold of 830V), and subsequently the bus voltage gradually decreases to 600V, then the second operating mode includes the previous first mode. The photovoltaic power generation system can still maintain the first mode instead of operating in the third mode.

[0055] The acquisition of the second operating mode relies on the controller's status recording and reading logic. The specific process is as follows: Real-time recording and updating: After acquiring the bus voltage, determining the first operating mode, and executing the closed loop of that mode in each round, the controller will store the currently running first operating mode (one of the first, second, and third modes) in real time in its own storage unit (such as a register or cache), overwriting the previous mode record. That is, the second operating mode is always synchronously updated to the most recently executed first operating mode. Triggering reading conditions: When the controller detects that the bus voltage is in one of the two hysteresis transition ranges, namely overvoltage recovery threshold ≤ bus voltage < bus high voltage threshold or bus undervoltage threshold < bus voltage < undervoltage recovery threshold, it will not re-determine the new first operating mode through the voltage range, but will trigger a historical status reading instruction; Determining the current mode: The controller retrieves the latest recorded second operating mode from the storage unit and directly determines it as the first operating mode of the current round, ensuring the continuity and stability of mode switching.

[0056] Based on the above explanation, it can be considered that the acquisition of the second working mode is the real-time storage and conditional reading of the historical operating modes by the controller, without the need for additional detection or calculation. By retaining the previous valid mode, the mode jitter problem caused by critical voltage fluctuations is solved.

[0057] In this embodiment, by setting two transitional ranges—overvoltage recovery threshold ≤ bus voltage < bus high voltage threshold and bus undervoltage threshold < bus voltage < undervoltage recovery threshold—and specifying that the second operating mode of the photovoltaic power generation system in the previous operation (i.e., the first operating mode executed in the previous round) is directly obtained as the current first operating mode within these ranges, hysteresis anti-jitter control in the critical voltage range is achieved. This effectively avoids frequent switching between the first and second modes when the bus voltage fluctuates slightly between the recovery threshold and the critical threshold. This ensures the stability of power transmission and the continuity of control logic, while reducing power surges and device losses caused by frequent mode switching. It further improves the fine control across the entire voltage range, making the system more stable and extending the equipment's service life.

[0058] S203. Run the first working mode corresponding to the first working interval to control the power transmission of the photovoltaic module to the DC bus or disconnect it.

[0059] In one embodiment, based on a previously determined first operating mode (first mode, second mode, or third mode), the controller can output corresponding control commands to directly regulate the power transmission status of the photovoltaic module to the DC bus, which will not be described in detail.

[0060] In another embodiment, during the operation of the first operating mode, the controller may perform the step of acquiring the bus voltage of the DC bus and subsequent steps.

[0061] It should be noted that while performing power control, the controller can repeatedly acquire the DC bus voltage and trigger subsequent operating mode determination and mode operation processes to build a closed-loop control of detection, decision-making, execution, and re-detection.

[0062] For example, if a sudden change in light intensity causes a sharp increase in photovoltaic power, the bus voltage will start to rise. The controller can identify this change in a timely manner by continuously collecting voltage data, and then re-determine the operating mode (such as switching from the first mode to the second mode) to achieve an instant response to voltage fluctuations.

[0063] Based on this, in this embodiment, by cycling through the first operating mode, collecting the bus voltage, and then determining the next mode, the system can dynamically adapt to various operating condition changes. When the photovoltaic power drops sharply due to cloud cover, the bus voltage may decrease. After the controller detects the voltage change, it can switch back from the second mode to the first mode to restore efficient power output. When the energy storage battery is fully charged or the load suddenly decreases, causing the bus voltage to approach the overvoltage threshold, the controller can quickly switch to the second mode or even the third mode to avoid voltage runaway. Based on the above closed-loop control, the photovoltaic system's response to changes in bus voltage can be ensured in real time and accurately, achieving a dynamic balance between efficiency and safety.

[0064] For the above steps S201-S203, please refer to the following for ease of explanation. Figure 3 and Figure 4 , Figure 3 This is a schematic diagram showing the relationship between the bus voltage range and the operating mode in a control method for a photovoltaic power generation system provided in an embodiment of this application; Figure 4 This is a schematic diagram of the working mode switching in a control method for a photovoltaic power generation system provided in an embodiment of this application.

[0065] like Figure 3 As shown, the vertical axis represents the DC bus voltage, and the horizontal axis represents time. The graph is divided into six key intervals, corresponding to different operating modes: Extreme overvoltage range of bus voltage (bus voltage ≥ bus overvoltage threshold) and extreme undervoltage range of bus voltage (bus voltage ≤ bus undervoltage threshold): correspond to the third mode (rapidly disconnect photovoltaic power to ensure equipment safety).

[0066] Critical overvoltage range of bus voltage (bus voltage ≥ bus high voltage threshold and bus voltage < bus overvoltage threshold): corresponds to the second mode (coordinated limiting, suppressing voltage rise).

[0067] The overvoltage recovery interval (bus voltage ≥ overvoltage recovery threshold and bus voltage < bus high voltage threshold) is the first transitional hysteresis interval, and the undervoltage recovery interval (bus voltage > bus undervoltage threshold and bus voltage < undervoltage recovery threshold) is the second transitional hysteresis interval. At this time, the second working mode of the previous operation (i.e. the first working mode of the previous round) is inherited to avoid frequent mode switching.

[0068] The normal bus voltage range (bus voltage ≥ undervoltage recovery threshold and bus voltage < overvoltage recovery threshold, including standard bus voltage) corresponds to the first mode (independent voltage regulation operation). Furthermore, the first mode must also be executed in the hysteresis range one (bus voltage ≥ overvoltage recovery threshold and bus voltage < bus high voltage threshold) and the critical overvoltage range (bus voltage ≥ bus high voltage threshold and bus voltage < bus overvoltage threshold).

[0069] And, refer to Figure 4 , Figure 4 The dynamic curves of the bus voltage rise / fall process are used to illustrate the specific logic of the operating mode switching, combined with an example (parameters continue from the previous example: standard bus voltage 750V, bus undervoltage threshold 550V, undervoltage recovery threshold 670V, overvoltage recovery threshold 830V, bus high voltage threshold 850V, bus overvoltage threshold 950V) for explanation: Example 1: The process of bus voltage first rising, then becoming overvoltage, and finally falling back to normal: Phase 1 (Bus Voltage Increase): Initial voltage 700V (within the normal range), only the first mode is operated; when the bus voltage rises to 840V (entering the overvoltage recovery range, i.e., 830V≤840V<850V), the first mode is inherited from the previous one (to avoid jitter); when the bus voltage rises to 860V (entering the critical overvoltage range of the bus voltage, i.e., 850V≤860V<950V), the second mode is operated simultaneously; when the bus voltage rises to 960V (entering the extreme overvoltage range of the bus voltage, i.e. ≥950V), the third mode is switched.

[0070] Phase 2 (Bus Voltage Drop Recovery): The bus voltage drops from 960V to 900V (still in the critical overvoltage range of the bus voltage), maintaining the second mode; the bus voltage drops to 840V (entering the hysteresis range), inheriting the second mode from the previous time; the bus voltage drops to 820V (entering the normal range), operating only the first mode.

[0071] Example 2: Bus voltage drop, undervoltage, recovery process: Phase 1 (Bus Voltage Reduction): Initial voltage 700V (normal range), only the first mode is operated; when the bus voltage drops to 660V (entering the hysteresis range, i.e., 550V<660V<670V), the first mode of the previous phase is inherited; when the bus voltage drops to 540V (entering the extreme undervoltage range of the bus voltage, i.e. ≤550V), the third mode is switched.

[0072] Phase 2 (Bus Voltage Rise and Recovery): The bus voltage rises from 540V to 600V (still in the hysteresis range), maintaining the third mode (in the undervoltage scenario, the third mode must continue until the bus voltage is away from the undervoltage threshold); when the bus voltage rises to 680V (entering the normal range), it switches to the first mode.

[0073] based on Figure 3 and Figure 4 Through the static division of bus voltage range and the dynamic switching process of working mode, the hierarchical range and mode binding, as well as the anti-jitter logic of hysteresis range, are intuitively demonstrated: it not only realizes the full-scenario control of extreme protection, critical amplitude limiting and normal high efficiency, but also avoids frequent mode switching caused by small voltage fluctuations by inheriting historical modes through the transition range, and ultimately ensures the stability, efficiency and safety of system operation.

[0074] In this embodiment, by acquiring the DC bus voltage in real time through the controller and determining the first operating mode based on multiple bus voltage ranges, the photovoltaic power generation system can proactively switch operating modes according to the actual state of the bus voltage. This changes the control logic in related technologies where the photovoltaic end passively follows the feedback from the power consumption end, enabling direct response to bus voltage fluctuations from the energy input side and improving the response speed of the photovoltaic power generation system to changes in bus voltage. Furthermore, in the first mode, the controller can independently maintain bus voltage stabilization control, ensuring efficient power output from the photovoltaic modules. In the second mode, it assists the first mode in limiting the output by appropriately reducing power output to suppress bus voltage rise, avoiding the risk of overvoltage exacerbated by high power output or energy waste caused by simply cutting off power, thus reducing the regulation burden on the power consumption end. In the third mode, it quickly disconnects the power transmission from the photovoltaic modules to the DC bus, which, compared to the hysteresis protection of related technologies, can more promptly prevent damage to devices from instantaneous voltage surges, improving equipment safety. Moreover, the clear correspondence between bus voltage ranges and operating modes clarifies the operating mode of the bus voltage, reduces operational oscillations, and ensures the long-term reliability of the system. Based on the acquired bus voltage, the controller can ensure that the photovoltaic power generation system can track changes in bus voltage in real time and dynamically adjust the control logic. This can solve the problem of response lag in traditional passive control, achieve immediate suppression of bus voltage fluctuations, and ensure stable operation of the DC bus.

[0075] In another embodiment, for the three modes described above, the controller can operate in a first operating mode according to the following example. For example, refer to... Figure 5 , Figure 5 This is a schematic flowchart illustrating the operation of the first working mode in a control method for a photovoltaic power generation system according to an embodiment of this application. Details are as follows: S501. When the first working mode is the first mode, obtain the photovoltaic open-circuit voltage of the photovoltaic module.

[0076] In one embodiment, the photovoltaic open-circuit voltage refers to the terminal voltage of the photovoltaic module in the open-circuit state (no load connected to the output terminal, and the output current is 0), and is one of the characteristic parameters of the photovoltaic module. Its value is closely related to the light intensity and ambient temperature, and is a key reference for the maximum power point tracking algorithm to determine the maximum power output point of the photovoltaic module.

[0077] As an example, the controller can acquire the open-circuit voltage of the photovoltaic (PV) module through hardware circuitry on the PV side (such as the control logic of the DC-DC converter). For instance, the connection between the PV module and the load (or the DC-DC converter) can be briefly disconnected, putting the PV module in an open-circuit state. Simultaneously, the voltage sampling module acquires the terminal voltage of the PV module in real time at this moment, which is the open-circuit voltage. After acquisition, the controller can restore the connection between the PV module and the load to minimize the impact on normal power output. This process can be completed in milliseconds, ensuring that effective parameters are acquired without significantly reducing power generation efficiency.

[0078] S502. If the photovoltaic open-circuit voltage is less than or equal to the preset standard bus voltage, the photovoltaic open-circuit voltage is multiplied by a preset coefficient to obtain a target voltage value, and the power corresponding to the target voltage value is taken as the maximum power point.

[0079] The maximum power point is the maximum power output of the photovoltaic module under the current operating conditions, with a preset coefficient greater than 0 and less than 1.

[0080] In one embodiment, the photovoltaic open-circuit voltage is the terminal voltage of the photovoltaic module in the open-circuit state, and its value reflects the power generation potential of the photovoltaic module under the current irradiance and temperature. When the photovoltaic open-circuit voltage is less than or equal to a preset standard bus voltage, it indicates that the voltage characteristics of the photovoltaic module are highly compatible with the system bus voltage. At this time, a target voltage value is obtained by converting the photovoltaic open-circuit voltage using a preset coefficient; the power output of the photovoltaic module at this target voltage value is the maximum power point under the current operating conditions, so as to quickly lock the maximum output power range of the photovoltaic module.

[0081] The preset coefficient is an empirical value based on the volt-ampere characteristics of photovoltaic modules, such as 0.7~0.8.

[0082] It should be noted that in the first mode, the controller can operate based on the MPPT (Maximum Power Point Tracking) algorithm. The MPPT algorithm can track the maximum power output point of the photovoltaic (PV) modules in real time (because the output characteristics of PV modules dynamically change with light intensity and ambient temperature). In the first mode, the system is in the normal voltage range (the bus voltage is regulated between the undervoltage recovery threshold and the overvoltage recovery threshold). At this time, the controller can continuously collect parameters such as the PV open-circuit voltage and output current, and combine this with the aforementioned preset coefficients or other MPPT algorithms (such as the perturbation observation method or the incremental conductance method) to continuously adjust the operating state (e.g., duty cycle) of the PV-side DC-DC converter, ensuring that the operating point of the PV modules always approaches the maximum power point. Therefore, this not only ensures efficient PV energy output but also maintains the stability of the DC bus voltage through power regulation, achieving the dual goals of efficient power generation and voltage stability.

[0083] S503 controls the photovoltaic modules to transmit power to the DC bus at their maximum power point.

[0084] In one embodiment, the controller can send control commands (such as adjusting the PWM duty cycle of the power switch) to the DC-DC converter on the photovoltaic side based on the parameters corresponding to the determined maximum power point (such as target voltage and target current), and dynamically adjust the output characteristics of the photovoltaic module: on the one hand, to stabilize the actual operating voltage and current of the photovoltaic module at the value corresponding to the maximum power point, ensuring that the output power reaches the maximum value under the current operating conditions; on the other hand, through the voltage conversion function of the converter, to adapt the output power of the photovoltaic module to the voltage level of the DC bus, so that energy can be stably and losslessly transmitted to the bus.

[0085] In this embodiment, under the first operating mode, the open-circuit voltage of the photovoltaic module is acquired. When this voltage is less than or equal to the preset standard bus voltage, the maximum power point under the current operating condition is quickly determined based on a preset coefficient. The photovoltaic module is then controlled to transmit power to the DC bus at this power point. This approach ensures efficient output of photovoltaic energy and reduces waste by leveraging the direct reflection of the open-circuit voltage on changes in light and temperature, as well as the accuracy of the coefficient calculation. Furthermore, the rapid response without the need for complex disturbance calculations allows for real-time adaptation to sudden changes in operating conditions. Simultaneously, the stable power transmission, combined with the independent voltage regulation logic of the first mode, prevents power fluctuations from impacting the DC bus, ensuring stable bus voltage control. Ultimately, a dynamic balance is achieved between efficient power generation and stable system operation, significantly improving the overall performance of the photovoltaic energy storage system.

[0086] For the first mode, in another embodiment, the controller can also be based on, as shown in the example below. Figure 6 The steps S601-S603 shown are executed. Details are as follows: S601. When the first working mode is the first mode, obtain the photovoltaic open-circuit voltage of the photovoltaic module.

[0087] The method for obtaining the open-circuit voltage of the photovoltaic system has already been explained above and will not be repeated here.

[0088] S602. If the photovoltaic open-circuit voltage is greater than the preset standard bus voltage, the photovoltaic port voltage of the photovoltaic module is used as the adjustment point, and the photovoltaic port voltage is iteratively adjusted using the perturbation observation method to determine the maximum power point of the photovoltaic module.

[0089] In one embodiment, the photovoltaic port voltage refers to the real-time voltage at the output terminal of the photovoltaic module when it is in actual working condition (connected to a load or connected to a DC-DC converter). It is the actual operating voltage of the photovoltaic module when transmitting power to the DC bus, and its value changes dynamically with factors such as load size, light intensity, and temperature.

[0090] It's important to note that the photovoltaic open-circuit voltage is the terminal voltage of the photovoltaic module when it's in an open-circuit state (no load connected to the output terminal, and the output current is 0). It represents an extreme case of the port voltage (in which case the port voltage equals the open-circuit voltage). However, in actual operation (with current output), the photovoltaic port voltage is always lower than the photovoltaic open-circuit voltage (following the volt-ampere characteristic of the photovoltaic module: as the output current increases, the port voltage decreases). Both reflect the voltage characteristics of the photovoltaic module; the open-circuit voltage serves as an upper limit reference for the port voltage, while the port voltage represents the dynamic value during actual operation.

[0091] The perturbation-observation method, specifically the MPPT algorithm, approximates the maximum power point through small perturbations and iterative power observations. Specifically, the controller first makes small adjustments to the photovoltaic port voltage (e.g., increasing or decreasing it by a tiny value, i.e., a perturbation), and then detects the change in output power before and after the adjustment: if the power increases, it indicates that the current adjustment direction is approaching the maximum power point, and the perturbation continues in that direction; if the power decreases, it indicates a deviation from the maximum power point, and the perturbation is reversed. Through repeated iterations, the port voltage is gradually stabilized at the voltage value corresponding to the maximum power point.

[0092] It should be noted that when the photovoltaic open-circuit voltage exceeds the preset standard bus voltage, it indicates that the voltage characteristics of the photovoltaic module are poorly adapted to the bus voltage (the photovoltaic module itself has high voltage potential, and directly estimating the maximum power point using the coefficient method is prone to deviation). In this case, the controller adjusts the photovoltaic port voltage using a perturbation observation method: each time the port voltage is slightly changed, the output power before and after the adjustment is compared to determine the direction of the maximum power point. This process iteratively adjusts until the port voltage value with the highest power (i.e., the maximum power point under the current operating condition) is found. This process accurately adapts to the characteristics of the photovoltaic module under high open-circuit voltage scenarios, ensuring stable tracking of the true maximum power point even under drastic changes in sunlight and temperature, thus guaranteeing efficient photovoltaic energy output.

[0093] S603. Based on the power corresponding to the photovoltaic port voltage after each adjustment, control the photovoltaic module to transmit power to the DC bus.

[0094] In one embodiment, after each small adjustment of the photovoltaic port voltage, the controller can calculate the output power (voltage × current) corresponding to the voltage in real time and use it as the target power; the controller then adjusts the photovoltaic-side DC-DC converter to stabilize the output power of the photovoltaic module at the target power and adapts the energy transmission to the DC bus voltage level.

[0095] This process involves continuous iteration of the perturbation observation method, with new adjustments corresponding to new power calculations. The new target power drives new transmission control, which can dynamically track the maximum power point drift caused by changes in illumination and temperature, ensuring that photovoltaics always outputs at the current optimal efficiency. It can also avoid impacts on the bus through stable power transmission, forming a real-time balance between high-efficiency power generation and system stability.

[0096] In this embodiment, under the first operating mode, when the open-circuit voltage of the photovoltaic system is greater than the preset standard bus voltage, the maximum power point is determined by iterative adjustment using the photovoltaic port voltage as the adjustment point and the perturbation observation method. Based on the corresponding power after each adjustment, the photovoltaic system controls the transmission of energy to the DC bus. This can accurately adapt to the characteristics of the photovoltaic module in high-voltage potential scenarios and improve energy utilization efficiency. At the same time, the transmission control based on the adjusted power allows the photovoltaic output power to smoothly adapt to the DC bus, avoiding the impact of power surges on the bus voltage. Combined with the voltage regulation logic of the first mode, the bus voltage regulation control is guaranteed. Ultimately, a dynamic balance between efficient power generation and stable system operation is achieved under complex operating conditions, significantly improving the adaptability and reliability of the photovoltaic system.

[0097] In one embodiment, for the second mode, the controller can also be based on, for example... Figure 7 The steps S701-S703 shown are executed. Details are as follows: S701. When the first working mode is the second mode, obtain the first voltage difference between the bus voltage and the preset bus high voltage threshold.

[0098] In one embodiment, the trigger condition for the second mode is that the bus voltage is greater than or equal to the bus high-voltage threshold and less than the bus overvoltage threshold. At this point, the bus voltage has entered the critical overvoltage range. That is, although the extreme danger value for triggering the third mode (power disconnection) has not been reached, it has exceeded the normal operating range, and it is necessary to actively suppress the voltage from rising further. The bus high-voltage threshold is the starting point of the critical overvoltage. Calculating the first voltage difference between the bus voltage and the bus high-voltage threshold can directly quantify the degree to which the voltage exceeds the critical intervention point: the larger the difference, the higher the overvoltage risk (the closer to the overvoltage threshold), and the stronger the suppression signal required; when the difference is 0, it means that the voltage has just reached the critical value, and only basic suppression is required. This difference design directly links the regulation intensity to the overvoltage risk, realizing intervention on demand and avoiding power waste caused by over-regulation.

[0099] S702. Perform proportional-integral calculation on the first voltage difference to obtain the first control signal quantity.

[0100] The first control signal is an adjustment signal used to suppress bus voltage overvoltage.

[0101] S703. Input the first control signal into the first mode to reduce the power transmitted from the photovoltaic module to the DC bus.

[0102] In one embodiment, the proportional-integral (PI) calculation is used as a closed-loop control algorithm to convert the first voltage difference into a smooth and precise adjustment signal. Its function is to balance rapid response and steady-state errorlessness: The proportional part (P): Based on the current magnitude of the first voltage difference, it outputs a control quantity proportional to the difference (the larger the difference, the stronger the output signal), achieving rapid suppression of overvoltage and preventing the voltage from rapidly approaching the overvoltage threshold. The integral part (I): Accumulates the sum of historical first voltage differences, eliminating static deviations (for example, if the voltage is consistently slightly higher than the high-voltage threshold, the integral part gradually strengthens the control signal until the voltage stabilizes within the target range), ensuring that the voltage eventually stabilizes near the high-voltage threshold, rather than experiencing prolonged small overvoltages.

[0103] In one embodiment, the aforementioned first control signal is the output of a PI calculation, essentially a negative power regulation signal used to suppress bus voltage overvoltage. In the second mode, the system is based on the first mode, and this signal is superimposed on the power control signal of the first mode, ultimately acting on the photovoltaic-side DC-DC converter: by reducing the output power of the photovoltaic modules (e.g., reducing the converter duty cycle), the energy input to the DC bus is reduced, thereby suppressing the bus voltage from continuing to rise and controlling it within the critical overvoltage range, avoiding triggering a more extreme third mode.

[0104] In this embodiment, in the second mode, the overvoltage risk is quantified by obtaining the first voltage difference between the bus voltage and the high voltage threshold. The first control signal quantity, which takes into account both fast response and steady-state stability, is obtained by proportional-integral calculation. This signal quantity is then input into the first mode to reduce the power transmission from the photovoltaic system to the DC bus. This can not only accurately suppress the continued rise of the bus voltage to avoid triggering the third mode of extreme protection, but also reduce the impact of excessive limiting on power generation efficiency by adjusting as needed. This achieves a dynamic balance between system safety and energy utilization efficiency in critical overvoltage scenarios.

[0105] As an example, the controller can also be based on, for example... Figure 8 The steps S801-S803 shown reduce the power transmitted from the photovoltaic modules to the DC bus. Details are as follows: S801, Obtain the second control signal corresponding to the maximum power point during the first mode operation.

[0106] The second control signal is the maximum power adjustment allowed for the photovoltaic module output during the process of determining the maximum power point.

[0107] In one embodiment, the second control signal is a reference adjustment signal generated by the controller to maintain the photovoltaic module's output at the maximum power point during the first mode operation. It is a quantitative representation of the maximum power range that the photovoltaic module is allowed to output (such as the duty cycle range of the DC-DC converter, current limit threshold, etc.). Therefore, the second control signal can be considered as the output result carrier in the first mode, directly reflecting the power adjustment boundary that the photovoltaic module can perform to track the maximum power point under the current operating conditions.

[0108] The aforementioned maximum power adjustment refers to the maximum range (i.e., the range within which the power can be increased or decreased) that the controller allows to dynamically adjust the output power in the first mode to ensure that the photovoltaic module always operates near its maximum power point. For example, when sunlight intensity increases, the maximum power point shifts upward, and the adjustment allows the power to increase accordingly; when sunlight intensity decreases, the adjustment allows the power to decrease, thus adapting to changes in operating conditions. This adjustment amount represents the boundary of the photovoltaic module's efficient output capability, ensuring maximum energy utilization without exceeding the equipment's safe operating range (such as avoiding overcurrent and overvoltage).

[0109] As an example, during the first mode of operation, after determining the current maximum power point, the controller, in conjunction with the hardware parameters of the photovoltaic module (such as rated power and maximum output current) and the safety constraints of the DC bus (such as the bus voltage regulation control range), calculates the maximum adjustable range of the photovoltaic module's output power (i.e., the maximum power adjustment amount) to maintain the target power. Finally, this adjustment range is converted into an electrical signal recognizable by the controller (such as the upper and lower limits of the PWM duty cycle and digital thresholds), which is the second control signal quantity, and stored in the controller's cache in real time as a reference adjustment parameter in the first mode.

[0110] Understandably, obtaining the second control signal corresponding to the maximum power point during the first mode operation can provide a reference framework for power control in subsequent modes (such as the second mode). In the second mode, the system needs to reduce the photovoltaic output power based on the first control signal (to suppress bus overvoltage), while the second control signal clarifies the maximum allowable adjustment range of the photovoltaic system in the first mode. Therefore, it can be assumed that the power reduction must be bounded by the second control signal (e.g., it cannot be lower than the lower limit of the maximum adjustment, to avoid excessive limiting leading to inefficient operation or shutdown of the equipment). By obtaining this signal, it can be ensured that the power regulation in the second mode achieves the goal of suppressing overvoltage without exceeding the safe operating capacity of the photovoltaic modules, thus achieving a balance between limiting and equipment protection.

[0111] S802. Input the first control signal into the control loop of the first mode and superimpose it with the second control signal to obtain the total control quantity.

[0112] S803, based on total control quantity, reduce the power transmitted from photovoltaic modules to the DC bus.

[0113] In one embodiment, the aforementioned control loop refers to a closed-loop control system that achieves maximum power output and bus voltage stabilization in the first mode. The inputs are the output characteristics (voltage, current) of the photovoltaic module and the DC bus voltage; the decision-making mechanism can be as described above. Figure 6 and Figure 7 The control logic is shown below. The execution stage can control the photovoltaic output power by adjusting the switching state (e.g., duty cycle) of the photovoltaic-side DC-DC converter. The feedback stage can collect the adjusted power and voltage in real time, compare them with the target values ​​(maximum power point, standard bus voltage), and continuously correct the control signal. That is, the control loop is the automatic adjustment mechanism that ensures the efficient and stable operation of the photovoltaic system in the first mode, and the second control signal (maximum power adjustment amount) is the output signal of this loop.

[0114] The above total control quantity is a comprehensive adjustment signal that is the superposition of the first control signal (overvoltage suppression signal of the second mode) and the second control signal (maximum power reference signal of the first mode). Its essence is the final control command that takes into account both the maximum power output reference and the overvoltage suppression requirement.

[0115] The first control signal is a negative adjustment quantity (aimed at reducing power), and its magnitude is positively correlated with the risk of bus overvoltage (the more severe the overvoltage, the stronger the negative adjustment); the second control signal is a positive reference quantity (reflecting the maximum allowable output power range in the first mode), defining the boundary for the safe and efficient output of photovoltaic modules; after being superimposed, the total control quantity will not exceed the safe range of the second control signal (avoiding excessive limiting that could lead to equipment inefficiency or abnormality), and can also achieve the goal of reducing power within the safe boundary to suppress overvoltage through the negative adjustment of the first control signal.

[0116] As an example, after obtaining the total control quantity, the controller can convert the total control quantity into specific operation instructions for the photovoltaic-side DC-DC converter (such as adjusting the PWM duty cycle of the power switch transistor), thereby reducing the actual power transmitted from the photovoltaic module to the DC bus by reducing the energy conversion efficiency of the converter (or limiting the output current or voltage).

[0117] It should be noted that after the photovoltaic transmission power decreases, the input power of the DC bus and the power consumed by the power consumption equipment (energy storage, load) are rebalanced, the bus voltage no longer continues to rise, and gradually falls from above the bus high voltage threshold to the overvoltage recovery threshold; when the bus voltage drops below the overvoltage recovery threshold, the first control signal gradually approaches 0, the total control quantity is restored to the second control signal, the photovoltaic power generation system exits the second mode and returns to the first mode for normal operation.

[0118] As an example, refer to Figure 9 , Figure 9This is a schematic diagram of the first and second modes of a control method for a photovoltaic power generation system provided in an embodiment of this application. The bus high-voltage threshold and bus voltage module: This module acquires the first voltage difference between the bus voltage and a preset bus high-voltage threshold. This first voltage difference is input to a PI controller (proportional-integral controller) to perform proportional-integral calculations on the first voltage difference, and outputs a first control signal (an adjustment signal used to suppress bus overvoltage).

[0119] Switch 1: Represents inputting the first control signal into the trigger logic of the first mode. When the photovoltaic power generation system enters the second mode, switch 1 is closed, and the first control signal is introduced into the control loop of the first mode.

[0120] The modules for photovoltaic reference voltage, photovoltaic voltage sampling value, and photovoltaic current sampling value correspond to: obtaining the second control signal quantity corresponding to the maximum power point during the first mode operation. Through these parameters, the voltage PI controller and current PI controller in the first mode work together to determine the output reference of the photovoltaic module at the maximum power point (i.e., the second control signal quantity, the maximum allowable power adjustment amount).

[0121] The signal superposition stage superimposes the first control signal and the second control signal to obtain the total control signal. The first control signal (negative adjustment) and the second control signal (maximum power reference) are superimposed here to generate the total control command.

[0122] The output impedance, PWM trigger, and switch 2 modules correspond to the following: reducing the power transmitted from the photovoltaic modules to the DC bus based on the total control quantity. After the total control quantity is adapted by the output impedance, it drives the PWM trigger signal to adjust the operating state (such as duty cycle) of the photovoltaic-side DC-DC converter, ultimately reducing the power transmission from the photovoltaic to the bus and achieving bus overvoltage suppression.

[0123] For example, suppose the bus voltage rises to 860V due to excess photovoltaic power (within the second mode range of 850V to 950V overvoltage threshold): In the second mode branch, the difference (10V) between the bus voltage of 860V and the bus high voltage threshold of 850V is input to the PI controller to generate the first control signal (negative power adjustment command); In the first mode branch, parameters such as the photovoltaic reference voltage and current sampling value determine the second control signal (the reference adjustment amount of the current maximum power point); After the two are superimposed, the total control amount drives the PWM trigger signal to reduce the energy transmission efficiency of the DC-DC converter, so that the photovoltaic output power is moderately reduced from the maximum power of the first mode, thereby suppressing the bus voltage from continuing to rise and stabilizing it in the safe range of 850V to 950V.

[0124] In another embodiment, reference is made to Figure 10 and Figure 11The first control signal can also be superimposed with the output of the current PI controller in the control loop of the first mode, or input to the output limiting module for superposition, to obtain the total control quantity finally output to the PWM module, without limitation.

[0125] It should be noted that the function of the superposition node for the first control signal varies depending on its location. Specifically, the first control signal is input to the current PI controller module for superposition, or it is combined with the output of the current PI controller in the control loop of the first mode (such as...). Figure 10 As shown, the superposition allows for priority adjustment of the photovoltaic output current to indirectly limit power, thus favoring power-side regulation. Additionally, the first control signal is input to the limiting module (such as...). Figure 11 By superimposing the signals (as shown), the final power output or bus voltage can be directly adjusted, resulting in more direct and rapid overvoltage suppression. In other words, the output of the first control signal can be applied to different locations, stemming from the flexibility and scenario adaptability of the control strategy: when the bus voltage overvoltage risk is extremely high, the first control signal directly acts on the power output terminal to achieve a rapid response, avoiding triggering extreme protection; when the overvoltage risk is moderate, the first control signal acts on the intermediate node of the current loop or voltage loop, balancing overvoltage suppression with the maximum power point tracking efficiency of the first mode, thus allowing the system to operate stably under different overvoltage scenarios and control priorities, demonstrating the flexible adaptability of the control algorithm.

[0126] It is understandable that the superposition point determines the regulation object (voltage, current or power) of the control loop, and the second control signal quantity, as the maximum regulation boundary of the first mode on the object, will inevitably differ due to the different physical properties of the object (the unit, range of voltage, current, power, and the associated logic with the maximum power point). The ultimate goal is to ensure that the superposition of the first control signal quantity and the second control signal quantity can achieve overvoltage suppression control in the corresponding link.

[0127] In this embodiment, the method of inputting the first control signal into the control loop of the first mode and superimposing it with the second control signal to obtain the total control quantity is not limited.

[0128] In this embodiment, by obtaining the second control signal corresponding to the maximum power point in the first mode (clearly defining the maximum allowable power adjustment boundary of photovoltaic), the first control signal (overvoltage suppression signal) is superimposed on it to obtain the total control quantity to reduce the photovoltaic transmission power. This not only allows for precise suppression of bus overvoltage with the help of the first control signal, but also constrains the adjustment range with the second control signal, ensuring that the power reduction does not exceed the range of safe and efficient photovoltaic operation, avoiding equipment abnormalities or efficiency losses caused by excessive limiting. Ultimately, a precise balance is formed between the safety of overvoltage suppression and the energy utilization efficiency of photovoltaic power generation, while ensuring the continuity of control and system stability during mode switching.

[0129] In another embodiment, for the third mode, refer to Figure 1 The photovoltaic power generation system may also include a DC-DC converter. The input terminal of the DC-DC converter is connected to the photovoltaic module, and the output terminal is connected to the DC bus. It is configured to adjust the duty cycle of the pulse width modulation signal of the power switch transistor and control the on and off durations of the power switch transistor to control the power transfer from the photovoltaic module to the DC bus. Based on this, when the first operating mode is the third mode, the controller can stop transmitting the pulse width modulation signal to the power switch transistor, control the power switch transistor to turn off, and disconnect the power transfer from the photovoltaic module to the DC bus.

[0130] In one embodiment, the power switch is the actuator in the DC-DC converter. Its function is to control the energy transfer path between the photovoltaic module and the DC bus by rapidly switching between two states: when on, energy flows from the photovoltaic module through the converter to the DC bus; when off, the energy transfer path is cut off, and the photovoltaic module stops supplying power to the bus. Its switching state is driven by a pulse width modulation (PWM) signal, which is the physical gate for realizing power control.

[0131] Duty cycle refers to the ratio of the on-time of the power switch to the total period within one PWM signal cycle. Adjusting the duty cycle directly changes the ratio of on to off time: when the duty cycle increases, the on-time becomes longer and the off-time becomes shorter, increasing the effective energy transfer time per unit time and thus increasing the power transferred from the photovoltaic system to the bus; conversely, when the duty cycle decreases, the on-time becomes shorter and the off-time becomes longer, decreasing the effective energy transfer time per unit time and thus reducing the power transferred from the photovoltaic system to the bus. In other words, the duty cycle is a parameter that quantifies the proportion of the power switch's operating time; adjusting it allows for precise control of the power transfer intensity.

[0132] Based on the above explanation, the DC-DC converter can be considered as the energy regulation hub between the photovoltaic module and the DC bus. By adjusting the duty cycle of the PWM signal of the power switch, the on / off time of the switch is controlled, thereby achieving precise regulation of the power transmitted from the photovoltaic to the bus (such as power tracking or limiting in the first and second modes).

[0133] When the photovoltaic power generation system enters the third mode (typically corresponding to the bus voltage reaching the bus overvoltage threshold, an extremely dangerous state), the controller can stop sending PWM signals to the power switching transistors, forcing them to remain off. At this time, the energy transmission path between the photovoltaic modules and the DC bus is completely cut off, and the photovoltaic system stops supplying power to the bus, thereby quickly curbing the continued rise in bus voltage and preventing overvoltage damage to energy storage devices, inverters, and other components, ensuring system safety. For example, when the controller stops sending PWM signals to the power switching transistors, it can enable... Figure 9 The switch after the PWM module is turned off.

[0134] When executing the third mode, the following should be cleared: Figures 9-11 The cumulative integral error value in each PI controller is used to recalculate and accumulate the integral error value during the next run of the first mode.

[0135] In this embodiment, a DC-DC converter with its input end connected to a photovoltaic module and its output end connected to a DC bus is configured. By adjusting the duty cycle of the pulse width modulation signal of the power switch, the on and off duration of the switch is controlled, enabling flexible regulation of power transmission from the photovoltaic module to the DC bus and ensuring efficient energy transmission under normal operating conditions. Simultaneously, when the first operating mode is the third mode (extreme overvoltage or undervoltage conditions), the power switch is forced to turn off by stopping the transmission of the pulse width modulation signal, completely disconnecting power transmission. This can quickly curb further increases in bus voltage and effectively prevent overvoltage damage to system components. This achieves precise power control under normal operating conditions and builds a reliable defense line under extreme overvoltage or undervoltage conditions, improving the operational stability and safety of the photovoltaic power generation system.

[0136] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0137] In another embodiment, such as Figure 2 As shown, the photovoltaic power generation system can be used to implement the control method of the photovoltaic power generation system described in the above method embodiments.

[0138] A photovoltaic power generation system may include one or more memories storing programs that can be run by a controller to generate instructions, causing the controller to execute the control method of the photovoltaic power generation system described in the above method embodiments according to the instructions.

[0139] Optionally, the memory may also store data. Optionally, the controller may also read data stored in the memory, which may be stored at the same memory address as the program, or the data may be stored at a different memory address than the program.

[0140] The controller and memory can be set up separately or integrated together; for example, integrated on the system on chip (SOC) of the terminal device.

[0141] This application also provides a computer program product that, when executed by a controller, implements the control method of the photovoltaic power generation system in any of the method embodiments of this application.

[0142] The computer program product can be stored in memory, for example, as a program. The program is eventually converted into an executable object file that can be executed by the controller after processes such as preprocessing, compilation, assembly, and linking.

[0143] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a computer, implements the control method of the photovoltaic power generation system in any embodiment of the method in this application. The computer program may be a high-level language program or an executable object program.

[0144] The computer-readable storage medium is, for example, memory. Memory can be volatile or non-volatile, or it can include both volatile and non-volatile memory. Non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory can be random access memory (RAM), which serves as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM).

[0145] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be a single item or multiple items.

[0146] It should be understood that in the various embodiments of this application, the order of the above-mentioned processes does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0147] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0148] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and modules described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0149] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for example, the division of modules is merely a logical functional division, and there may be other division methods in actual implementation; for example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection between apparatuses or modules may be electrical, mechanical, or other forms.

[0150] The modules described as separate components may or may not be physically separate. Similarly, the components shown as modules may or may not be physical modules; they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0151] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0152] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A photovoltaic power system, characterized by, The application relates to a photovoltaic system, comprising: a photovoltaic module configured to convert solar energy into electric energy; a direct-current bus connected with the photovoltaic module and configured to receive the electric energy transmitted by the photovoltaic module and transmit the electric energy to an electric energy consumption device; a controller configured to: acquire a bus voltage of the direct-current bus; determine a first working mode corresponding to the bus voltage based on a plurality of preset bus voltage intervals, wherein each bus voltage interval corresponds to a working mode, the working mode is divided into a first mode for maintaining voltage stabilization control of the bus voltage, a second mode for assisting the first mode in limiting the bus voltage, and a third mode for disconnecting the photovoltaic module from transmitting power to the direct-current bus; run the first working mode corresponding to the first working interval to control the power transmission or disconnection of the photovoltaic module to the direct-current bus.

2. The photovoltaic power system of claim 1, wherein, The controller configured to determine the first working mode corresponding to the bus voltage based on the plurality of preset bus voltage intervals is configured to: if the bus voltage is greater than or equal to a preset bus overvoltage threshold value or less than or equal to a preset bus undervoltage threshold value, determine that the first working mode is the third mode; if the bus voltage is greater than or equal to a preset bus high-voltage threshold value and less than the bus overvoltage threshold value, determine that the first working mode is the second mode, wherein the bus high-voltage threshold value is greater than the bus undervoltage threshold value; if the bus voltage is greater than or equal to a preset undervoltage recovery threshold value and less than the bus overvoltage threshold value, determine that the first working mode is the first mode, wherein the undervoltage recovery threshold value is greater than the bus undervoltage threshold value.

3. The photovoltaic power system of claim 2, wherein, The controller configured to determine the first working mode corresponding to the bus voltage based on the plurality of preset bus voltage intervals is further configured to: if the bus voltage is greater than or equal to an overvoltage recovery threshold value and less than the bus high-voltage threshold value, or the bus voltage is greater than the bus undervoltage threshold value and less than the undervoltage recovery threshold value, acquire a second working mode of the photovoltaic power generation system in the last operation; the overvoltage recovery threshold value is greater than the undervoltage recovery threshold value; determine the second working mode as the first working mode.

4. The photovoltaic power system according to any one of claims 1 to 3, characterized in that, The controller configured to run the first working mode corresponding to the first working interval is further configured to: when the first working mode is the first mode, acquire a photovoltaic open-circuit voltage of the photovoltaic module; if the photovoltaic open-circuit voltage is less than or equal to a preset standard bus voltage, multiply the photovoltaic open-circuit voltage by a preset coefficient to obtain a target voltage value, and take the power corresponding to the target voltage value as a maximum power point; the maximum power point is the maximum power output by the photovoltaic module under the current working condition, and the preset coefficient is greater than 0 and less than 1; control the photovoltaic module to transmit power to the direct-current bus at the maximum power point.

5. The photovoltaic power system according to any one of claims 1 to 3, wherein The controller configured to run the first working mode corresponding to the first working interval is further configured to: when the first working mode is the first mode, acquire a photovoltaic open-circuit voltage of the photovoltaic module; If the photovoltaic open-circuit voltage is greater than a preset standard bus voltage, a photovoltaic port voltage of the photovoltaic module is taken as an adjustment point, a perturbation and observation method is used to iteratively adjust the photovoltaic port voltage, and a maximum power point of the photovoltaic module is determined; Based on the power corresponding to the photovoltaic port voltage after each adjustment, the photovoltaic module is controlled to transmit power to the direct-current bus.

6. The photovoltaic power system according to any one of claims 1 to 3, wherein The controller running the first working mode corresponding to the first working interval is further configured to: When the first working mode is the second mode, a first voltage difference between the bus voltage and a preset bus high-voltage threshold is obtained; A proportional-integral calculation is performed on the first voltage difference to obtain a first control signal quantity; the first control signal quantity is an adjustment signal for suppressing overvoltage of the bus voltage; The first control signal quantity is input into the first mode to reduce the power transmitted by the photovoltaic module to the direct-current bus.

7. The photovoltaic power system of claim 6, wherein, The controller inputting the first control signal quantity into the first mode to reduce the power transmitted by the photovoltaic module to the direct-current bus is configured to: A second control signal quantity corresponding to a maximum power point when the first mode is running is obtained; the second control signal quantity is a maximum power adjustment quantity allowed to be output by the photovoltaic module in the process of determining the maximum power point; The first control signal quantity is input into the control loop of the first mode and superimposed with the second control signal quantity to obtain a total control quantity; The power transmitted by the photovoltaic module to the direct-current bus is reduced based on the total control quantity.

8. The photovoltaic power system according to any one of claims 1 to 3, wherein The photovoltaic power generation system further comprises a direct-current converter, an input end of the direct-current converter is connected with the photovoltaic module, and an output end of the direct-current converter is connected with the direct-current bus, and the direct-current converter is configured to adjust a duty cycle of a pulse width modulation signal of a power switch tube, control on and off durations of the power switch tube, and control power transmission of the photovoltaic module to the direct-current bus; The controller running the first working mode corresponding to the first working interval is further configured to: When the first working mode is the third mode, the pulse width modulation signal is stopped from being transmitted to the power switch tube, the power switch tube is controlled to be turned off, and the power transmission of the photovoltaic module to the direct-current bus is disconnected.

9. The photovoltaic power system according to any one of claims 1 to 3, wherein The controller running the first working mode corresponding to the first working interval to control the power transmission or disconnection of the photovoltaic module to the direct-current bus is configured to: During the running of the first working mode, the step of obtaining the bus voltage of the direct-current bus and subsequent steps are performed.

10. A control method of a photovoltaic power generation system, characterized by, The photovoltaic power generation system comprises a photovoltaic module configured to convert solar energy into electric energy, and a direct-current bus connected with the photovoltaic module and configured to receive the electric energy transmitted by the photovoltaic module and transmit the electric energy to an electric energy consumption device. The method comprises: Obtaining a bus voltage of the direct-current bus; Determine a first working mode corresponding to the bus voltage according to a plurality of preset bus voltage intervals; each of the bus voltage intervals corresponds to one working mode; the working mode includes a first mode for maintaining the bus voltage, a second mode for assisting the first mode to limit the bus voltage, and a third mode for disconnecting the photovoltaic module from transmitting power to the DC bus; Run the first working mode corresponding to the first working interval to control the power transmission or disconnection of the photovoltaic module to the DC bus.

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