Control method and device of optical storage grid-connected and off-grid air conditioning system and photovoltaic air conditioner

Abstract

The invention relates to a control method and device for an optical storage grid-connected and off-grid air conditioner system, a photovoltaic air conditioner and a storage medium, and the method comprises the steps that under the condition that the optical storage grid-connected and off-grid air conditioner system is in an off-grid mode, the current moment is obtained, the time range to which the current moment belongs is determined, and the charge state of an energy storage system is obtained; and performing linkage control on the photovoltaic air conditioner, the photovoltaic system and the energy storage system according to the time range and the charge state of the energy storage system. Therefore, stable operation can still be maintained under the off-grid condition of photovoltaic power generation power fluctuation. The problem that an air conditioner is frequently started and stopped due to insufficient photovoltaic power supply of a traditional storage-free off-grid photovoltaic air conditioning system in the dim light periods such as morning and night is solved, the service life and operation reliability of core components such as an air conditioner compressor are guaranteed, indoor temperature fluctuation is remarkably smoothed, and the use experience of a user is improved.

Description

Technical Field

[0001] This application relates to the field of smart home technology, and in particular to a control method, device and photovoltaic air conditioner for a photovoltaic storage and off-grid air conditioning system. Background Technology

[0002] With the widespread application of photovoltaic energy and the increasing demand for energy conservation and emission reduction, grid-connected photovoltaic air conditioning systems without energy storage are gradually becoming an important direction in the field of photovoltaic applications due to their advantages of not requiring energy storage devices and having controllable costs. This type of system is designed with both grid-connected and off-grid operating modes. When the grid is normal, photovoltaic power generation prioritizes supplying the air conditioning load, and excess power can be connected to the grid or distributed to other electrical equipment, realizing the efficient utilization of photovoltaic energy and conforming to the current development trend of diversified energy utilization.

[0003] To cope with emergencies such as grid failures, off-grid photovoltaic air conditioning systems without energy storage are equipped with a mode switching function. When the grid is abnormal, they automatically switch to off-grid mode, where photovoltaic power generation drives the indoor and outdoor units of the air conditioner independently, ensuring the basic cooling or heating needs of the air conditioner. However, photovoltaic power generation is significantly affected by natural factors such as sunlight intensity and weather changes, and has inherent randomness and uncertainty. Its output power will fluctuate greatly with the alternation of day and night and changes in sunlight.

[0004] In off-grid mode, when the photovoltaic output power cannot stably meet the operating power requirements of the air conditioner's indoor and outdoor units, especially during the early morning and evening when sunlight is weak, the air conditioner is prone to frequent shutdowns and restarts. This frequent start-stop not only severely shortens the lifespan of core components such as the air conditioner compressor and reduces the overall reliability of the unit, but also causes excessive fluctuations in indoor temperature, seriously affecting the user experience. Summary of the Invention

[0005] To address the issue of frequent shutdowns and restarts of air conditioners in off-grid mode when the photovoltaic output power cannot stably meet the operating power requirements of the indoor and outdoor units, especially during periods of low sunlight in the early morning and evening, this application provides a control method, device, and photovoltaic air conditioner for a photovoltaic-storage-connected off-grid air conditioning system. The specific technical solution is as follows: In a first aspect, this application provides a control method for a photovoltaic-storage-grid-connected off-grid air conditioning system. The photovoltaic-storage-grid-connected off-grid air conditioning system includes a photovoltaic air conditioner, a photovoltaic system, and an energy storage system. The photovoltaic air conditioner, the photovoltaic system, and the energy storage system are all connected to a DC bus. The method includes: When the photovoltaic storage and off-grid air conditioning system is in off-grid mode, obtain the current time and determine the time range to which the current time belongs; Obtain the state of charge of the energy storage system; Based on the time range and the state of charge of the energy storage system, the photovoltaic air conditioner, the photovoltaic system, and the energy storage system are controlled in a coordinated manner.

[0006] In an optional implementation, the photovoltaic-storage-off-grid air conditioning system further includes an auxiliary power supply connected to the photovoltaic system. Before obtaining the current time, the system further includes: When the photovoltaic system is ready to generate electricity, the auxiliary power supply is started to supply power to the photovoltaic-storage-off-grid air conditioning system, so that the photovoltaic-storage-off-grid air conditioning system is ready to start and operate. During the operation of the photovoltaic system, the DC bus voltage is always stabilized through the energy storage system.

[0007] In an optional implementation, the step of coordinating the control of the photovoltaic air conditioner, the photovoltaic system, and the energy storage system based on the time range and the state of charge of the energy storage system includes: When the time range is the first time range, the following linkage control is performed on the photovoltaic air conditioner, the photovoltaic system, and the energy storage system: If the photovoltaic air conditioner is turned on, detect whether the state of charge of the energy storage system is greater than a preset first threshold. When the state of charge of the energy storage system is greater than a preset first threshold, the photovoltaic system and the energy storage system are controlled to jointly drive the photovoltaic air conditioner to operate; When the state of charge of the energy storage system is less than or equal to a preset first threshold, the photovoltaic system and the energy storage system are controlled to jointly drive the operation of the photovoltaic air conditioner, and the compressor frequency of the photovoltaic air conditioner is gradually reduced to reduce the power supply of the energy storage system until the power generation of the photovoltaic system and the power consumption of the photovoltaic air conditioner reach a balance, and the energy storage system stops supplying power. If the photovoltaic air conditioner is not turned on, check whether the state of charge of the energy storage system is less than a preset second threshold. When the state of charge of the energy storage system is less than a preset second threshold, the photovoltaic system is controlled to charge the energy storage system. When the state of charge of the energy storage system reaches a preset second threshold, the photovoltaic system is controlled to stop generating electricity.

[0008] In an optional implementation, the step of coordinating the control of the photovoltaic air conditioner, the photovoltaic system, and the energy storage system based on the time range and the state of charge of the energy storage system includes: When the time range is the second time range, the following linkage control is performed on the photovoltaic air conditioner, the photovoltaic system, and the energy storage system: If the power supply of the photovoltaic system is greater than the power consumption of the photovoltaic air conditioner, the state of charge of the energy storage system is detected to be less than a preset second threshold. When the state of charge of the energy storage system is less than a preset second threshold, the surplus electrical energy of the photovoltaic system is used to charge the energy storage system. If the power supply of the photovoltaic system is less than the power consumption of the photovoltaic air conditioner, the photovoltaic system and the energy storage system are controlled to jointly drive the operation of the photovoltaic air conditioner, and the compressor frequency of the photovoltaic air conditioner is gradually reduced, and the power supply of the energy storage system is reduced until the power generation of the photovoltaic system and the power consumption of the photovoltaic air conditioner reach a balance, and the energy storage system stops supplying power. If the power supply of the photovoltaic system is equal to the power consumption of the photovoltaic air conditioner, only the photovoltaic system is controlled to drive the photovoltaic air conditioner to operate, maintaining the current compressor frequency of the photovoltaic air conditioner.

[0009] In an optional implementation, the step of coordinating the control of the photovoltaic air conditioner, the photovoltaic system, and the energy storage system based on the time range and the state of charge of the energy storage system includes: When the time range is the third time range, the following linkage control is performed on the photovoltaic air conditioner, the photovoltaic system, and the energy storage system: The photovoltaic system and the energy storage system are controlled to jointly drive the operation of the photovoltaic air conditioner, and the compressor frequency of the photovoltaic air conditioner is gradually reduced until the power generation of the photovoltaic system approaches the preset power threshold, the compressor frequency of the photovoltaic air conditioner drops to the preset frequency threshold, and the photovoltaic-storage-off-grid air conditioning system shuts down. In the process of gradually reducing the compressor frequency of the photovoltaic air conditioner, the state of charge of the energy storage system is detected in real time to see if it is less than a preset third threshold. When the state of charge of the energy storage system is less than a preset third threshold, the compressor of the photovoltaic air conditioner is turned off, the photovoltaic-storage-off-grid air conditioning system is shut down, and the photovoltaic system is controlled to charge the energy storage system until the power generation of the photovoltaic system approaches the preset power threshold.

[0010] In one optional implementation, the gradual reduction of the compressor frequency of the photovoltaic air conditioner includes: Real-time monitoring of the state of charge of the energy storage system, and finding the step interval where the state of charge of the energy storage system is located; Obtain the first frequency reduction step size corresponding to the stepped interval, and gradually reduce the compressor frequency of the photovoltaic air conditioner according to the first frequency reduction step size; or, The real-time light intensity is obtained by the irradiance sensor of the photovoltaic system, and the light intensity range in which the real-time light intensity is located is found. Obtain the second frequency reduction step size corresponding to the light intensity range, and gradually reduce the compressor frequency of the photovoltaic air conditioner according to the second frequency reduction step size.

[0011] In one optional implementation, the gradual reduction of the compressor frequency of the photovoltaic air conditioner includes: Obtain the power difference between the power supplied by the photovoltaic system and the power consumed by the photovoltaic air conditioner; Find the third frequency reduction step size corresponding to the power difference, and gradually reduce the compressor frequency of the photovoltaic air conditioner according to the third frequency reduction step size; or, Obtain a fixed base frequency reduction step size and determine the rate of decrease in the replenishment power of the energy storage system; Find the correction step size corresponding to the rate of decrease in the replenished power, and obtain the sum of the fixed base frequency reduction step size and the correction step size; The compressor frequency of the photovoltaic air conditioner is gradually reduced according to the sum of the fixed base frequency reduction step size and the correction step size.

[0012] In one optional implementation, the gradual reduction of the compressor frequency of the photovoltaic air conditioner includes: The power generation attenuation rate of the photovoltaic system is calculated in real time, and a linear frequency reduction curve of the compressor frequency is fitted based on the attenuation rate. The compressor frequency of the photovoltaic air conditioner is gradually reduced according to the linear frequency reduction curve of the compressor frequency. or, When the power generation of the photovoltaic system decays to the critical power generation threshold, the compressor frequency of the photovoltaic air conditioner is gradually reduced according to the basic frequency reduction step size; When the state of charge of the energy storage system reaches the critical state threshold, the compressor frequency of the photovoltaic air conditioner is gradually reduced according to the emergency frequency reduction step size; or, Predict the power supply duration of the photovoltaic system and divide the power supply duration into multiple sub-duration intervals; Determine the target sub-time interval in which the current moment is located from among the multiple sub-time intervals; The compressor frequency of the photovoltaic air conditioner is gradually reduced according to the frequency reduction step size corresponding to the target sub-duration interval; Among them, the frequency reduction step size corresponding to each of the sub-time intervals gradually increases.

[0013] Secondly, this application provides a control device for a photovoltaic-storage-grid-connected off-grid air conditioning system. The photovoltaic-storage-grid-connected off-grid air conditioning system includes a photovoltaic air conditioner, a photovoltaic system, and an energy storage system. The photovoltaic air conditioner, the photovoltaic system, and the energy storage system are all connected to a DC bus. The device includes: The range determination module is used to obtain the current time and determine the time range to which the current time belongs when the photovoltaic storage and off-grid air conditioning system is in off-grid mode; A state acquisition module is used to acquire the state of charge of the energy storage system. The linkage control module is used to perform linkage control on the photovoltaic air conditioner, the photovoltaic system and the energy storage system according to the time range and the state of charge of the energy storage system.

[0014] Thirdly, a photovoltaic air conditioner is also provided, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus. Memory, used to store computer programs; When the processor executes the program stored in the memory, it implements the control method of the optical storage and off-grid air conditioning system described in any of the first aspects above.

[0015] Fourthly, a storage medium is also provided, wherein the storage medium stores instructions that, when run on a computer, cause the computer to execute the control method of the optical storage and off-grid air conditioning system described in any of the first aspects above.

[0016] Fifthly, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to execute any of the above-mentioned control methods for optical storage and off-grid air conditioning systems.

[0017] Compared with the prior art, the technical solution provided in this application has the following advantages: The control method for the photovoltaic-storage-grid-connected off-grid air conditioning system provided in this application includes a photovoltaic air conditioner, a photovoltaic system, and an energy storage system. All three systems are connected to a DC bus. When the photovoltaic-storage-grid-connected off-grid air conditioning system is in off-grid mode, the current time is obtained, the time range to which the current time belongs is determined, and the state of charge of the energy storage system is obtained. Based on the time range and the state of charge of the energy storage system, the photovoltaic air conditioner, photovoltaic system, and energy storage system are subjected to coordinated control. By dynamically linking and coordinating the photovoltaic air conditioner, photovoltaic system, and energy storage system according to the time range to which the current time belongs and the real-time state of charge of the energy storage system when the photovoltaic-storage-grid-connected off-grid air conditioning system is in off-grid mode, stable operation can still be maintained under off-grid conditions where photovoltaic power generation fluctuates. It effectively solves the problem of frequent start-stop of air conditioners caused by insufficient photovoltaic power supply during low light periods such as dawn and dusk in traditional off-grid photovoltaic air conditioning systems without energy storage. It not only ensures the service life and operational reliability of core components such as air conditioning compressors, but also significantly smooths indoor temperature fluctuations and improves the user experience. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0021] Figure 1 A schematic diagram of a grid-connected air conditioning system without energy storage is provided in an embodiment of this application; Figure 2 This application provides a schematic diagram of the structure of an off-grid air conditioning system without a storage system. Figure 3 This application provides a schematic diagram of the structure of an off-grid air conditioning system for photovoltaic energy storage. Figure 4 A schematic diagram of a photovoltaic-storage grid-connected air conditioning system provided in an embodiment of this application; Figure 5A schematic diagram illustrating the implementation process of a control method for a photovoltaic-storage-off-grid air conditioning system provided in this application embodiment; Figure 6 A schematic diagram illustrating the implementation flow of another control method for a photovoltaic-storage-off-grid air conditioning system provided in this application embodiment; Figure 7 A schematic diagram illustrating the implementation process of another control method for a photovoltaic-storage-off-grid air conditioning system provided in this application embodiment; Figure 8 A schematic diagram illustrating the implementation process of another control method for a photovoltaic-storage-off-grid air conditioning system provided in this application embodiment; Figure 9 A schematic diagram of the structure of a control device for a photovoltaic storage and off-grid air conditioning system provided in this application embodiment; Figure 10 This is a structural schematic diagram of a photovoltaic air conditioner provided in an embodiment of this application. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0024] like Figure 1 The diagram shown is a structural schematic of a grid-connected air conditioning system without energy storage provided in this application embodiment. The grid-connected air conditioning system without energy storage may include a photovoltaic system, an outdoor unit of the air conditioner, an indoor unit of the air conditioner, and a power grid. The photovoltaic system is used to convert solar energy into electrical energy. The outdoor unit of the air conditioner (which may include a compressor, main controller, etc.) and the indoor unit of the air conditioner (which may include an indoor fan) serve as system loads, together constituting the main cooling or heating function of the grid-connected air conditioning system without energy storage. The power grid is used to provide stable voltage support for the grid-connected air conditioning system without energy storage in grid-connected mode, receive surplus electrical energy generated by the photovoltaic system, and supplement electrical energy when the photovoltaic system's power generation is insufficient.

[0025] like Figure 2The diagram shown is a structural schematic of an off-grid air conditioning system without a storage system provided in an embodiment of this application. Figure 1 The structure shown removes the grid connection, and in off-grid mode, the air conditioner's outdoor and indoor units are driven entirely by electricity generated by the photovoltaic system. However, due to the intermittent and fluctuating nature of photovoltaic power generation, especially in the early morning or evening when sunlight is weak, the photovoltaic output power may not be able to continuously meet the air conditioner's operating needs, easily leading to frequent start-ups and shutdowns of the air conditioner.

[0026] To overcome the shortcomings of the aforementioned off-grid systems without energy storage, embodiments of this application introduce an energy storage system to provide a photovoltaic-storage-off-grid air conditioning system, which... Figure 1 Based on the system structure shown, an energy storage system (including battery packs and energy storage DC / DC converter) is added to the DC bus. This photovoltaic-storage-off-grid air conditioning system has both grid-connected and off-grid modes. For photovoltaic-storage-off-grid air conditioning systems in off-grid mode, such as Figure 3 The diagram shown is a structural schematic of a photovoltaic-storage off-grid air conditioning system provided in an embodiment of this application. The photovoltaic-storage off-grid air conditioning system includes a photovoltaic air conditioner, a photovoltaic system, and an energy storage system. The photovoltaic air conditioner, the photovoltaic system, and the energy storage system are all connected to a DC bus.

[0027] The aforementioned photovoltaic air conditioner refers to an air conditioning device with a DC power supply interface, which may include a compressor, indoor fan, outdoor fan, main controller, etc. The drive and control circuit of the photovoltaic air conditioner (such as the DC / AC converter required for compressor drive) can directly obtain power from the DC bus.

[0028] The aforementioned photovoltaic system refers to a power generation unit used to convert solar energy into electrical energy. It may include photovoltaic modules and a photovoltaic DC / DC converter connected to a DC bus to achieve maximum power point tracking (MPPT) and feed photovoltaic power into the DC bus.

[0029] The aforementioned energy storage system refers to an energy storage and power buffer device connected to the DC bus. It may include a battery pack and an energy storage DC / DC converter connected to the DC bus. In off-grid mode, the energy storage system stabilizes the DC bus voltage through the energy storage DC / DC converter and charges or discharges according to the real-time difference between photovoltaic power generation and photovoltaic air conditioning load demand in order to balance the instantaneous power between power generation and power consumption.

[0030] The aforementioned DC bus refers to the electrical connection bus that provides a common DC voltage platform for each unit (photovoltaic system, energy storage system, photovoltaic air conditioner and other DC loads), serving as the core hub for energy aggregation and distribution.

[0031] In addition, the photovoltaic-storage-grid-connected off-grid air conditioning system may also include an auxiliary power supply, which is connected to the photovoltaic system. The auxiliary power supply is used to extract a small amount of electrical energy from the photovoltaic system when the photovoltaic system has initial power generation capacity but the power is insufficient. After conversion, the energy is used to power the main controller and other core control circuits, thereby waking up and starting the entire control system and enabling it to operate.

[0032] For photovoltaic-storage-off-grid air conditioning systems in grid-connected mode, such as Figure 4 The diagram shown is a structural schematic of a photovoltaic-storage grid-connected air conditioning system provided in an embodiment of this application. Figure 3 Based on the existing structure, a connection to the power grid is added. In grid-connected mode, the DC bus voltage is stabilized by a grid-side converter. The grid is connected to the DC bus through a grid-connected inverter (grid-side DC / AC converter) to provide stable voltage and frequency support for the entire photovoltaic-storage grid-connected air conditioning system. It receives surplus electricity from photovoltaic power generation to achieve grid connection and supplements the system with electricity when photovoltaic power generation is insufficient. In grid-connected mode, the auxiliary power supply typically does not need to draw power from the photovoltaic modules of the photovoltaic system to start the photovoltaic-storage grid-connected air conditioning system; it can directly obtain the power required for startup from the grid. Among them, the energy storage system mainly maintains its state of charge in preparation for off-grid operation (for example, the stored capacity of the energy storage system needs to be greater than 95% of its rated capacity). Photovoltaic power generation prioritizes supplying the air conditioning load, and surplus electricity can be connected to the grid or used to charge the energy storage system.

[0033] like Figure 5 The diagram shown is a schematic representation of the implementation flow of a control method for a photovoltaic-storage-off-grid air conditioning system provided in this application embodiment, which may specifically include the following steps: S501: When the photovoltaic-storage-off-grid air conditioning system is in off-grid mode, obtain the current time and determine the time range to which the current time belongs.

[0034] In this embodiment, when the photovoltaic-storage-off-grid air conditioning system is in off-grid mode, the current time can be obtained and the time range to which the current time belongs can be determined. Off-grid mode means the system is not connected to the power grid and requires power to be supplied to the photovoltaic air conditioning system through the photovoltaic system and energy storage system. The current time can be real-time clock information during operation, representing a specific point in time during the day. The time range to which the current time belongs can be divided according to the typical patterns of solar intensity changes. For example, the first time range can correspond to the period of low light from when the photovoltaic system starts generating electricity in the early morning until the light intensity stabilizes. The second time range can correspond to the stable period during the day when there is sufficient sunlight and the photovoltaic system generates high power. The third time range can correspond to the period in the evening when the light intensity begins to continuously decrease until power generation stops. This embodiment does not limit this specific time range.

[0035] S502, obtain the state of charge of the energy storage system.

[0036] In this embodiment, the state of charge (SOC) of the energy storage system is obtained. SOC is a key parameter reflecting the percentage of remaining charge in an energy storage system (such as a battery) relative to its total capacity. Obtaining the SOC allows for the assessment of the system's energy reserves and the determination of its charge / discharge capabilities. The SOC level directly determines whether the energy storage system can replenish power for an air conditioning load or whether it needs to prioritize charging itself.

[0037] Specifically, the state of charge (SOC) of an energy storage system can be determined using at least one of the following model estimation methods: integration method, voltage lookup table method, and Kalman filtering method. The integration method involves detecting the charging and discharging current of the energy storage system and calculating the SOC in real time by integrating the data with the nominal battery capacity. The voltage lookup table method involves measuring the terminal voltage of the energy storage system and estimating the current SOC by referring to a table based on the relationship between the battery open-circuit voltage (OCV) and the SOC. Model estimation methods such as Kalman filtering combine parameters such as battery internal resistance, temperature, and historical charging and discharging data to estimate the SOC in real time using a battery model, improving estimation accuracy and robustness. This application does not limit the scope of this method.

[0038] S503 performs coordinated control of the photovoltaic air conditioner, photovoltaic system and energy storage system based on the time range and the state of charge of the energy storage system.

[0039] In this embodiment of the application, the photovoltaic air conditioner, the photovoltaic system and the energy storage system can be linked and controlled according to the time range determined by the above steps and the obtained state of charge of the energy storage system.

[0040] Based on the above description of the technical solution provided in the embodiments of this application, when the photovoltaic-storage-off-grid air conditioning system is in off-grid mode, the current time is obtained, the time range to which the current time belongs is determined, the state of charge of the energy storage system is obtained, and the photovoltaic air conditioning, photovoltaic system and energy storage system are linked and controlled according to the time range and the state of charge of the energy storage system.

[0041] In this way, when the photovoltaic-storage-connected off-grid air conditioning system is in off-grid mode, dynamic linkage and coordinated control are performed on the photovoltaic air conditioning, photovoltaic system, and energy storage system based on the current time range and the real-time charge status of the energy storage system. This enables stable operation even under off-grid conditions where photovoltaic power generation fluctuates. It effectively solves the problem of frequent start-stop of air conditioning in traditional off-grid photovoltaic air conditioning systems without energy storage during low-light periods such as dawn and dusk due to insufficient photovoltaic power supply. This not only ensures the service life and operational reliability of core components such as the air conditioning compressor but also significantly smooths indoor temperature fluctuations, improving the user experience.

[0042] like Figure 6The diagram shown is a schematic representation of the implementation flow of another control method for a photovoltaic-storage-off-grid air conditioning system provided in this application embodiment. This method may specifically include the following steps: S601: When the photovoltaic-storage-off-grid air conditioning system is in off-grid mode, obtain the current time and determine the time range to which the current time belongs.

[0043] In this embodiment of the application, when the photovoltaic-storage-off-grid air conditioning system is in off-grid mode (i.e. disconnected from the power grid), the current time can be obtained and the time range to which the current time belongs can be determined.

[0044] It should be noted that before obtaining the current moment, it is necessary to ensure that the photovoltaic-storage-grid-connected off-grid air conditioning system meets the basic conditions for startup and operation. Specifically, this includes: when the photovoltaic system is ready to generate electricity, starting the auxiliary power supply to power the photovoltaic-storage-grid-connected off-grid air conditioning system, thus enabling it to start and operate; and during the operation of the photovoltaic system, maintaining a stable DC bus voltage through the energy storage system. Here, "generating electricity" refers to whether the photovoltaic system has initial power generation capability. This can be determined by detecting whether the photovoltaic system's output voltage exceeds a certain startup threshold (e.g., photovoltaic system output voltage above 50V). When the photovoltaic system's output voltage continuously exceeds this threshold for a certain period (e.g., 30 seconds), and the ambient light intensity is higher than the photovoltaic system's startup illuminance (e.g., ambient light intensity above 50W / m²), the photovoltaic system is considered to have the conditions for generating electricity. "Startup and operation conditions" refers to the conditions under which the photovoltaic-storage-grid-connected off-grid air conditioning system can operate normally.

[0045] Specifically, once the photovoltaic system is ready to generate electricity, the auxiliary power supply connected to the output of the photovoltaic system is activated. This auxiliary power supply extracts a small initial power from the photovoltaic modules, which, after conversion, provides a stable and reliable operating voltage (e.g., 12V) for the system's main controller, sensors, communication modules, and other core control circuits. After the control system is powered on, it will sequentially complete hardware initialization, software loading, self-testing of each subsystem (e.g., drive modules), and communication link establishment. When all key control units have completed power-on initialization and reported a ready status, and can correctly read key operating parameters (e.g., DC bus voltage, energy storage SOC, ambient temperature), the entire photovoltaic-storage-grid-connected air conditioning system is considered to have the conditions for startup and operation. After the photovoltaic-storage-grid-connected air conditioning system is operating normally, the energy storage system can preferentially operate in voltage control mode through its energy storage DC / DC converter. Its core task is to always stabilize the DC bus voltage, precisely maintaining the bus voltage at the rated operating voltage point (e.g., 350V or 400V) regardless of whether photovoltaic power is fed in or air conditioning loads are connected.

[0046] S602, obtain the state of charge of the energy storage system.

[0047] In this embodiment of the application, this step is similar to step S502 above, and will not be described in detail here.

[0048] S603, when the time range is the first time range, performs the following linkage control on the photovoltaic air conditioner, photovoltaic system and energy storage system.

[0049] In this embodiment of the application, when the time range is a first time range, the photovoltaic air conditioner, photovoltaic system and energy storage system are subjected to the linkage control of steps S604 to S609. The first time range refers to the time period when the light intensity is weak and the photovoltaic system can be woken up, which can be the low light period in the early morning, such as 05:00-08:00.

[0050] S604, If the photovoltaic air conditioner is turned on, detect whether the state of charge of the energy storage system is greater than the preset first threshold.

[0051] In this embodiment, if the photovoltaic air conditioner is turned on, the state of charge (SOC) of the energy storage system is detected to be greater than a preset first threshold. The preset first threshold is used to measure whether the energy storage system has sufficient power reserves to provide necessary power support for the photovoltaic air conditioner's startup and initial operation during low-light periods, while preventing the energy storage system from entering a deep discharge state to protect its lifespan (e.g., 30%). If the SOC is greater than the preset first threshold, it means that the energy storage system has relatively abundant power; conversely, it means that the energy storage system's power is at a low level.

[0052] S605 controls the photovoltaic system and the energy storage system to jointly drive the photovoltaic air conditioner when the state of charge of the energy storage system is greater than a preset first threshold.

[0053] In this embodiment, when the state of charge of the energy storage system is greater than a preset first threshold, the photovoltaic system and the energy storage system are controlled to jointly drive the photovoltaic air conditioner. When the state of charge of the energy storage system is greater than the preset first threshold, it indicates that the energy storage system has sufficient energy reserves to participate in power supply.

[0054] Specifically, the photovoltaic DC / DC converter in the photovoltaic system is controlled to operate in maximum power point tracking mode, converting current sunlight into electrical energy to feed into the DC bus as much as possible. The energy storage DC / DC converter in the energy storage system is controlled to operate in discharge mode (or power compensation mode) to dynamically adjust the discharge power according to real-time load demand while maintaining a stable DC bus voltage, thus supplementing the insufficient photovoltaic power generation. The compressor and fan driver of the photovoltaic air conditioner draw power from the stable DC bus and start running. At this time, the load power of the photovoltaic air conditioner is met by the combined power generation of the photovoltaic system and the discharge power of the energy storage system, thereby ensuring that the photovoltaic air conditioner can start smoothly and operate stably even in the early morning when sunlight is insufficient, avoiding start-up failures or frequent start-stops caused by insufficient instantaneous photovoltaic power.

[0055] S606 When the state of charge of the energy storage system is less than or equal to a preset first threshold, the photovoltaic system and the energy storage system are controlled to jointly drive the operation of the photovoltaic air conditioner, and the compressor frequency of the photovoltaic air conditioner is gradually reduced to reduce the power supply of the energy storage system until the power generation of the photovoltaic system and the power consumption of the photovoltaic air conditioner reach a balance, and the energy storage system stops supplying power.

[0056] In this embodiment of the application, when the state of charge of the energy storage system is less than or equal to a preset first threshold, the photovoltaic system and the energy storage system are controlled to jointly drive the operation of the photovoltaic air conditioner, and the compressor frequency of the photovoltaic air conditioner is gradually reduced to reduce the power supply of the energy storage system until the power generation of the photovoltaic system and the power consumption of the photovoltaic air conditioner reach a balance, and the energy storage system stops supplying power.

[0057] In one optional embodiment, gradually reducing the compressor frequency of the photovoltaic air conditioner may include: real-time monitoring of the state of charge (SOC) of the energy storage system, identifying the tiered range of the SOC's state of charge, obtaining a first frequency reduction step size corresponding to the tiered range, and gradually reducing the compressor frequency of the photovoltaic air conditioner according to the first frequency reduction step size. Alternatively, real-time irradiance may be obtained through an irradiance sensor of the photovoltaic system, identifying the irradiance range of the real-time irradiance, obtaining a second frequency reduction step size corresponding to the irradiance range, and gradually reducing the compressor frequency of the photovoltaic air conditioner according to the second frequency reduction step size.

[0058] The stepped intervals refer to multiple consecutive numerical ranges pre-divided for the state of charge (SOC) of the energy storage system. Each interval corresponds to a specific level of energy shortage and a corresponding control response speed. The first frequency reduction step size refers to the unit of frequency change (e.g., in Hz / s) set by the control system to reduce the compressor frequency within the stepped interval of the SOC. The size of this step size is negatively correlated with the stepped interval of the SOC; that is, the lower the SOC, the larger the corresponding frequency reduction step size, in order to alleviate the discharge burden of the energy storage system more quickly. For example, the following mapping relationship can be defined: when the SOC is in the interval (20%, 30%), the first frequency reduction step size is 0.5 Hz / s; when the SOC is in the interval (10%, 20%), the step size is 1.0 Hz / s; and when the SOC is in the interval (0%, 10%), the step size is 2.0 Hz / s. Based on the real-time monitored SOC, the stepped interval to which it belongs is determined, and the corresponding first frequency reduction step size is called to continuously or intermittently reduce the compressor frequency.

[0059] The illuminance range refers to a pre-defined range of consecutive values ​​for ambient illuminance, used to characterize the potential level and stability of photovoltaic power generation. The second frequency reduction step size refers to the amount of frequency change per unit time (e.g., in Hz / s) set within this illuminance range to reduce the compressor frequency. This step size is typically negatively correlated with illuminance; the weaker the illuminance, the more limited or unstable the photovoltaic power generation capacity, and the larger the corresponding frequency reduction step size, to more quickly match the load power with the reduced power generation. For example, the following mapping relationship can be defined: when the real-time illuminance is below 100 W / m², the second frequency reduction step size is 1.0 Hz / s; when the illuminance is in the range [100 W / m², 200 W / m²), the step size is 0.5 Hz / s; when the illuminance is greater than or equal to 200 W / m², the step size is 0.2 Hz / s. Based on the real-time readings of the irradiance sensor, the current illuminance range is determined, and the corresponding second frequency reduction step size is applied to adjust the compressor frequency.

[0060] S607 If the photovoltaic air conditioner is not turned on, check whether the state of charge of the energy storage system is less than the preset second threshold.

[0061] In this embodiment of the application, if the photovoltaic air conditioner is not turned on, the state of charge of the energy storage system is detected to be less than a preset second threshold (e.g., 95%). The preset second threshold can be set as a threshold when the energy storage system is close to a fully charged state, which is used to determine whether the energy storage system needs to be charged and when to stop charging to prevent overcharging.

[0062] S608 controls the photovoltaic system to charge the energy storage system when the state of charge of the energy storage system is less than a preset second threshold.

[0063] In this embodiment, when the state of charge of the energy storage system is less than a preset second threshold, the photovoltaic system is controlled to charge the energy storage system. When the state of charge of the energy storage system is detected to be less than the preset second threshold, it indicates that the energy storage system is not fully charged and has charging potential, so the control system executes the charging logic.

[0064] Specifically, the control system executes the charging logic by controlling the photovoltaic DC / DC converter of the photovoltaic system to operate in maximum power point tracking mode, maximizing photovoltaic power generation. It also controls the energy storage DC / DC converter of the energy storage system to operate in charging mode, directing all the electrical energy generated by the photovoltaic system (after deducting its own standby losses) to the energy storage system to charge it and accumulate energy. In this mode, the DC bus voltage is stabilized by the energy storage DC / DC converter of the energy storage system while simultaneously controlling the charging process.

[0065] S609 controls the photovoltaic system to stop generating electricity when the state of charge of the energy storage system reaches a preset second threshold.

[0066] In this embodiment, when the state of charge of the energy storage system reaches a preset second threshold, the photovoltaic system is controlled to stop generating electricity. When the state of charge of the energy storage system reaches or exceeds the preset second threshold, it indicates that the energy storage system is nearly fully charged. To prevent overcharging damage to the energy storage system and to conserve the ineffective losses of the photovoltaic system when there is no storage demand, the control system executes protective shutdown logic.

[0067] Specifically, the protective shutdown logic executed by the control system can be to control the photovoltaic DC / DC converter of the photovoltaic system to exit the maximum power point tracking mode, stop extracting power from the photovoltaic system, or put it into a standby sleep state, at which time the photovoltaic system is in an unloaded or open circuit state.

[0068] like Figure 7 The diagram shown is a schematic representation of the implementation flow of another control method for a photovoltaic-storage-off-grid air conditioning system provided in this application embodiment, which may specifically include the following steps: S701: When the photovoltaic-storage-off-grid air conditioning system is in off-grid mode, obtain the current time and determine the time range to which the current time belongs.

[0069] In this embodiment of the application, this step is similar to step S601 above, and will not be described in detail here.

[0070] S702, obtain the state of charge of the energy storage system.

[0071] In this embodiment of the application, this step is similar to step S502 above, and will not be described in detail here.

[0072] S703, when the time range is the second time range, performs the following linkage control on the photovoltaic air conditioner, photovoltaic system and energy storage system.

[0073] In this embodiment, when the time range is a second time range, steps S704 to S707 of the linkage control are performed on the photovoltaic air conditioner, the photovoltaic system, and the energy storage system. The second time range can be a period of daytime with sufficient sunlight and high output power of the photovoltaic system, such as 08:00–17:00.

[0074] S704 If the power supply of the photovoltaic system is greater than the power consumption of the photovoltaic air conditioner, detect whether the state of charge of the energy storage system is less than the preset second threshold.

[0075] In this embodiment, if the power supply of the photovoltaic system is greater than the power consumption of the photovoltaic air conditioner, the state of charge of the energy storage system is detected to be less than a preset second threshold. The preset second threshold is used to determine whether the energy storage system is in a rechargeable state (not fully charged), thereby determining the destination of the surplus energy.

[0076] S705, when the state of charge of the energy storage system is less than a preset second threshold, controls the surplus electricity of the photovoltaic system to charge the energy storage system.

[0077] In this embodiment, when the state of charge of the energy storage system is less than a preset second threshold, the surplus electrical energy of the photovoltaic system is controlled to charge the energy storage system. Specifically, the photovoltaic DC / DC converter of the photovoltaic system is controlled to maintain maximum power point tracking operation. The bidirectional DC / DC converter of the energy storage system is controlled to operate in charging mode, directing all or a preset proportion of the photovoltaic power generation exceeding the air conditioning load demand (i.e., surplus electrical energy) to the energy storage system for charging, thereby achieving energy storage. The load of the photovoltaic air conditioner is directly powered by the photovoltaic system.

[0078] S706 If the power supply of the photovoltaic system is less than the power consumption of the photovoltaic air conditioner, the photovoltaic system and the energy storage system are controlled to jointly drive the operation of the photovoltaic air conditioner, and the compressor frequency of the photovoltaic air conditioner is gradually reduced, and the power supply of the energy storage system is reduced until the power generation of the photovoltaic system and the power consumption of the photovoltaic air conditioner reach a balance, and the energy storage system stops supplying power.

[0079] In this embodiment, if the power supply of the photovoltaic system is less than the power consumption of the photovoltaic air conditioner, the photovoltaic system and the energy storage system are controlled to jointly drive the operation of the photovoltaic air conditioner, and the compressor frequency of the photovoltaic air conditioner is gradually reduced to reduce the power supply of the energy storage system until the power generation of the photovoltaic system and the power consumption of the photovoltaic air conditioner reach a balance, and the energy storage system stops supplying power.

[0080] In one optional embodiment, gradually reducing the compressor frequency of the photovoltaic air conditioner may include: obtaining the power difference between the power supplied by the photovoltaic system and the power consumed by the photovoltaic air conditioner; finding the third frequency reduction step size corresponding to the power difference; and gradually reducing the compressor frequency of the photovoltaic air conditioner according to the third frequency reduction step size. Alternatively, a fixed base frequency reduction step size may be obtained, and the rate of decrease in the replenishment power of the energy storage system may be determined. A correction step size corresponding to the rate of decrease in the replenishment power may be found, and the sum of the fixed base frequency reduction step size and the correction step size may be obtained. The compressor frequency of the photovoltaic air conditioner may be gradually reduced according to the sum of the fixed base frequency reduction step size and the correction step size. The power difference refers to the algebraic difference between the total power generated by the photovoltaic system and the total power consumed by the photovoltaic air conditioning system (including compressors, fans, etc.) from the DC bus in real time. A positive difference indicates a surplus in photovoltaic power supply, while a negative difference indicates insufficient photovoltaic power supply and the need for energy storage or other power sources to supplement it. The third frequency reduction step size refers to the preset compressor frequency reduction per unit time for different negative power difference intervals. The larger the power deficit (i.e., the absolute value of the difference), the more severe the power supply gap of the photovoltaic system, and the more quickly the load needs to be reduced to match the power generation capacity. Therefore, the corresponding third frequency reduction step size should be larger. For example, the following mapping relationship can be defined: when the power difference is within the range of [-0.5kW, 0) (i.e., the deficit is small), the third frequency reduction step size is set to 0.2Hz / s; when the power difference is within the range of [-1.0kW, -0.5kW) (i.e., the deficit is moderate), the third frequency reduction step size is set to 0.5Hz / s; when the power difference is less than -1.0kW (i.e., the deficit is large), the third frequency reduction step size is set to 1.0Hz / s. The power difference is calculated in real time, and the corresponding third frequency reduction step size is found according to the preset mapping table. The compressor frequency is then dynamically adjusted accordingly until the power difference approaches zero.

[0081] The fixed base frequency reduction step size refers to a pre-set, basic, and relatively conservative frequency reduction step size (e.g., 0.3 Hz / s) as a baseline for smooth frequency reduction, ensuring the basic stability of control actions and avoiding the impact of sudden frequency changes on photovoltaic air conditioning. The rate of decrease in the energy storage system's supplementary power (i.e., discharge power) refers to the rate of change of the supplementary power (i.e., discharge power) provided by the energy storage system to compensate for insufficient photovoltaic power supply per unit time. It reflects the speed at which power rebalances after frequency reduction measures are implemented. If this rate is fast (e.g., a negative value indicates that the supplementary power is decreasing rapidly), it indicates that the frequency reduction measures are effective and the load demand is rapidly approaching the generating capacity. The correction step size refers to the increment or decrement (unit: Hz / s) of the fixed base frequency reduction step size dynamically adjusted according to the magnitude and direction of the rate of decrease in the supplementary power. The mapping relationship can be as follows: when the rate of decrease of the charge is relatively fast (e.g., less than -0.2kW / min), the correction step size can be negative (e.g., -0.1Hz / s) to slightly slow down the frequency reduction speed and prevent over-matching due to excessive frequency reduction, which would require reverse adjustment; when the rate of decrease of the charge is relatively slow or positive, the correction step size can be positive or zero to maintain or appropriately accelerate the frequency reduction speed.

[0082] For example, the fixed base frequency reduction step size is 0.3 Hz / s. Real-time calculation shows the current energy storage system's replenishment rate is -0.25 kW / min. The corresponding correction step size for this reduction rate is found to be -0.05 Hz / s. Therefore, the actual execution step size is 0.3 Hz / s + (-0.05 Hz / s) = 0.25 Hz / s. The compressor frequency is then gradually reduced in steps of 0.25 Hz / s.

[0083] In addition, after each reduction in the compressor frequency of the photovoltaic air conditioner, it can be left to stand still for a period of time (e.g., 3 seconds) to check whether the power generation of the photovoltaic system and the power consumption of the photovoltaic air conditioner are balanced. If they are balanced, the adjustment can be stopped.

[0084] S707 If the power supply of the photovoltaic system is equal to the power consumption of the photovoltaic air conditioner, only control the photovoltaic system to drive the operation of the photovoltaic air conditioner and maintain the current compressor frequency of the photovoltaic air conditioner.

[0085] In this embodiment of the application, if the power supply of the photovoltaic system is equal to the power consumption of the photovoltaic air conditioner, only the photovoltaic system is controlled to drive the photovoltaic air conditioner to operate, maintaining the current compressor frequency of the photovoltaic air conditioner.

[0086] like Figure 8 The diagram shown is a schematic representation of the implementation flow of a control method for a photovoltaic-storage-off-grid air conditioning system provided in this application embodiment, which may specifically include the following steps: S801: When the photovoltaic-storage-off-grid air conditioning system is in off-grid mode, obtain the current time and determine the time range to which the current time belongs.

[0087] In this embodiment of the application, this step is similar to step S601 above, and will not be described in detail here.

[0088] S802, obtain the state of charge of the energy storage system.

[0089] In this embodiment of the application, this step is similar to step S602 above, and will not be described in detail here.

[0090] S803, when the time range is the third time range, performs the following linkage control on the photovoltaic air conditioner, photovoltaic system and energy storage system.

[0091] In this embodiment of the application, when the time range is a third time range, the photovoltaic air conditioner, photovoltaic system and energy storage system are subjected to the linkage control of steps S804 to 806. The third time range can be the period from the duration of evening sunlight until it stops, such as 17:00–20:00.

[0092] S804 controls the photovoltaic system and energy storage system to jointly drive the operation of the photovoltaic air conditioner, and gradually reduces the compressor frequency of the photovoltaic air conditioner until the power generation of the photovoltaic system approaches the preset power threshold, the compressor frequency of the photovoltaic air conditioner drops to the preset frequency threshold, and the photovoltaic-storage-off-grid air conditioning system shuts down.

[0093] In this embodiment, the photovoltaic system and energy storage system jointly drive the operation of the photovoltaic air conditioner, gradually reducing the compressor frequency until the photovoltaic system's power generation approaches a preset power threshold. At this point, the compressor frequency drops to a preset frequency threshold, and the photovoltaic-storage-off-grid air conditioning system shuts down. The preset power threshold (e.g., 100W) is a pre-set minimum power level (e.g., 100W) sufficient to maintain basic operation of the system control circuit. It can be set based on the total power consumption of key control units such as the main controller, communication module, and sensors in standby mode, serving as a low-power threshold. This is used to determine whether the current photovoltaic power generation has declined to a level that can only sustain the control system itself and cannot support the operation of the main load, such as the air conditioner compressor. The preset frequency threshold (e.g., 10Hz or 0Hz) is the pre-set minimum safe operating frequency or shutdown frequency allowed for the compressor. It represents the lower limit of the frequency at which the compressor can operate stably without liquid slugging, vibration, or other malfunctions, or directly represents the command value for stopping operation. When the compressor frequency drops to this threshold, it indicates that the load has been reduced to a minimum or completely stopped.

[0094] Specifically, gradually reducing the compressor frequency of a photovoltaic (PV) air conditioner can include: calculating the attenuation rate of the PV system's power generation in real time, fitting a linear frequency reduction curve for the compressor frequency based on the attenuation rate, and gradually reducing the compressor frequency of the PV air conditioner according to the linear frequency reduction curve. Alternatively, when the PV system's power generation attenuates to a critical power generation threshold, gradually reducing the compressor frequency of the PV air conditioner according to a basic frequency reduction step size; when the energy storage system's state of charge reaches a critical state threshold, gradually reducing the compressor frequency of the PV air conditioner according to an emergency frequency reduction step size; or, predicting the duration of the PV system's power supply, dividing the duration into multiple sub-duration intervals, determining the target sub-duration interval from these sub-duration intervals, and gradually reducing the compressor frequency of the PV air conditioner according to the frequency reduction step size corresponding to the target sub-duration interval, wherein the frequency reduction step size corresponding to each sub-duration interval gradually increases.

[0095] The attenuation rate refers to the rate at which the output power of the photovoltaic system decreases per unit time. It can be calculated by monitoring the power difference between adjacent time points and dividing by the time interval, reflecting the rate of decrease in solar irradiance. The critical power generation threshold refers to a preset absolute or relative value of the photovoltaic system's power generation (e.g., 20% of peak power or an absolute power value such as 1kW), used to indicate that the photovoltaic system's power supply capacity is significantly insufficient, triggering the need to actively reduce the load. The basic frequency reduction step size refers to the relatively gradual step size of the compressor frequency reduction used when the frequency reduction is first triggered (i.e., the photovoltaic system's power generation decays to the critical power generation threshold) (e.g., 0.3Hz / s). The critical state threshold refers to a preset safe value (e.g., 75%) for the energy storage system's state of charge. The emergency frequency reduction step size refers to a larger frequency reduction step size (e.g., 1.0Hz / s) used when the energy storage system's state of charge reaches the critical state threshold. This step size is larger than the basic frequency reduction step size, aiming to reduce the load more quickly and rapidly alleviate the discharge pressure on the energy storage system. The duration of power supply refers to the remaining time (e.g., 10 minutes) that the photovoltaic system is expected to continue to provide effective power (e.g., power exceeding standby demand), estimated by prediction algorithms (such as linear extrapolation or exponential fitting) based on the current power generation of the photovoltaic system and its changing trend.

[0096] For example, if the photovoltaic power attenuation threshold is set to 50W and the critical state threshold is 70%, when the photovoltaic system's power generation attenuates to 50W, a base frequency reduction of 1Hz / s is triggered. If the energy storage's state of charge is less than the critical state threshold of 70% at this time, the system immediately switches to emergency frequency reduction mode, rapidly reducing the frequency to the preset frequency threshold (0Hz) at an amplitude of 2.5Hz / time to shut down the system and start the photovoltaic system to charge the energy storage system, so that the photovoltaic system's power generation approaches the preset power threshold (100W). For example, based on historical data and real-time photovoltaic power change trends, the duration of photovoltaic power supply in the evening is estimated (assuming the photovoltaic system's power generation is not lower than the preset power threshold of 100W, with 60 minutes remaining). This is divided into three frequency reduction phases (first 20 minutes, middle 20 minutes, and last 20 minutes), with the frequency reduction amplitude gradually increasing in each phase (e.g., 0.8Hz / time in the first phase, 1.5Hz / time in the second phase, and 2.2Hz / time in the third phase). Before the end of each phase, the state of charge of the energy storage system is checked. If the state of charge is ≥70%, the compressor frequency of the photovoltaic air conditioner is reduced to shutdown as planned; otherwise, the system directly enters the final phase of rapid shutdown.

[0097] For a linear frequency reduction curve of the compressor frequency fitted based on the decay rate, a matching compressor frequency reduction curve can be determined by a control algorithm (such as proportional mapping) based on the calculated real-time decay rate. For example, if the decay rate is -0.1 kW / min, it can be mapped to the compressor frequency decreasing linearly at a rate of -0.5 Hz / min.

[0098] S805, while gradually reducing the compressor frequency of the photovoltaic air conditioner, detects in real time whether the state of charge of the energy storage system is less than the preset third threshold.

[0099] In this embodiment, during the gradual reduction of the compressor frequency of the photovoltaic air conditioner, the state of charge of the energy storage system is monitored in real time to see if it is less than a preset third threshold. The preset third threshold refers to a safety baseline for the energy storage system's energy reserves (e.g., 70%), used to prevent deep discharge of the energy storage and ensure normal system startup the following morning.

[0100] S806: When the state of charge of the energy storage system is less than the preset third threshold, the compressor of the photovoltaic air conditioner is turned off, the photovoltaic-storage-off-grid air conditioning system is shut down, and the photovoltaic system is controlled to charge the energy storage system until the power generation of the photovoltaic system approaches the preset power threshold.

[0101] In this embodiment of the application, when the state of charge of the energy storage system is less than a preset third threshold, the compressor of the photovoltaic air conditioner is turned off, the photovoltaic-storage-off-grid air conditioning system is shut down, and the photovoltaic system is controlled to charge the energy storage system until the power generation of the photovoltaic system approaches the preset power threshold.

[0102] Furthermore, in this application embodiment, the control method of the photovoltaic storage and off-grid air conditioning system provided in this application embodiment is described with reference to specific examples: The photovoltaic-storage-connected off-grid air conditioning system includes a photovoltaic system, an energy storage system, an auxiliary power supply, and a photovoltaic air conditioner. The photovoltaic system is connected to the DC bus via a photovoltaic DC / DC converter. The auxiliary power supply is connected to the photovoltaic system, and the energy storage system is connected to the DC bus via a bidirectional DC / DC converter. The photovoltaic air conditioner, including a main controller, an indoor unit, and a compressor, is also connected to the DC bus. The compressor is connected to the DC bus via a drive DC / AC converter.

[0103] In grid-connected mode, the DC bus of the photovoltaic-storage-off-grid air conditioning system is connected to the grid via a grid-side DC / AC converter. At the same time, the auxiliary power supply is connected to the grid. In this mode, the voltage of the DC bus is stabilized by the grid-side DC / AC converter, eliminating the need for the energy storage system to provide power. However, the grid-side DC / AC converter can provide power to the energy storage system, allowing the energy storage system to maintain a stable state of charge of more than 95% of its rated capacity, thus preparing for the off-grid mode.

[0104] In off-grid mode, the photovoltaic-storage-grid-connected air conditioning system uses a bidirectional DC / DC converter from the energy storage system to stabilize the DC bus. The auxiliary power source draws power from the photovoltaic system to supply the entire system. When the photovoltaic system is ready to generate electricity, the auxiliary power source activates, energizing the entire system's control system and enabling the system to start and operate.

[0105] Specifically, when the sun rises in the morning, the photovoltaic system supplies power to wake up the entire photovoltaic-storage and off-grid air conditioning system. At this time, the bidirectional DC / DC converter of the energy storage system stabilizes the DC bus voltage, and the photovoltaic DC / DC converter operates optimally. If the photovoltaic air conditioner is turned on at this time, the power generation of the photovoltaic system and the power generation of the energy storage system will jointly drive the photovoltaic air conditioner to start and operate. Within the current time range, although the sunlight intensity is relatively weak, the photovoltaic air conditioner can operate stably with the support of the energy storage system. If the photovoltaic air conditioner is not turned on, the power generation of the photovoltaic system will charge the energy storage system. After the energy storage system is fully charged, the photovoltaic system will stop generating power and wait for the photovoltaic air conditioner to start. If the photovoltaic air conditioner is running at this time, and the state of charge of the energy storage system is less than 30%, the target frequency of the photovoltaic air conditioner compressor will be synchronously limited or reduced to reduce the power supply of the energy storage system until the power supply of the energy storage system is close to zero, so that the power consumption of the photovoltaic air conditioner and the power generation of the photovoltaic system are matched.

[0106] During periods of good sunlight, the bidirectional DC / DC converter of the energy storage system stabilizes the DC bus voltage, while the photovoltaic DC / DC converter operates at optimal performance. The photovoltaic system primarily powers the photovoltaic air conditioner. If the photovoltaic system generates surplus electricity beyond what is needed for the air conditioner, and the energy storage system is not fully charged, the excess electricity can be used to charge the energy storage system. However, if the photovoltaic system's power generation cannot meet the air conditioner's demand, the energy storage system needs to continue supplementing power. Simultaneously, the target frequency of the air conditioner's compressor is reduced to decrease the amount of power supplied by the energy storage system, until the supplementary power from the energy storage system approaches zero, thus achieving a balance between the photovoltaic system's power generation and the air conditioner's power consumption.

[0107] As sunlight gradually weakens in the evening, the photovoltaic (PV) system's power generation slowly decreases. To ensure stable operation of the entire system, the energy storage system needs to replenish its power. During this process, the compressor's operating target frequency needs to be gradually reduced to decrease the power demand of the PV air conditioner until the PV system's power generation approaches zero. At this point, the compressor's target frequency drops to zero, and the PV air conditioner shuts down. Throughout this process, the energy storage system's state of charge (SOC) needs to be maintained above 70% to provide energy reserves for startup the following morning. If, during the reduction of the compressor's SOC, the energy storage system's SOC drops below 70%, the compressor is immediately shut down, the PV air conditioner stops, and the PV system's meager power generation charges the energy storage system until the PV power generation approaches zero.

[0108] The entire photovoltaic-storage off-grid air conditioning system is primarily powered by the photovoltaic system, with the energy storage system playing a supporting role. A small-capacity energy storage system supplements the power supply during mornings and evenings when sunlight is insufficient but air conditioning is still needed. Through the coordinated control of the photovoltaic, energy storage, and air conditioning systems, the entire system operates stably off-grid, resolving the issue of frequent air conditioner startups during mornings and evenings with weak sunlight, which is problematic in off-grid environments without energy storage. This extends the lifespan of the air conditioners and improves the user experience.

[0109] Corresponding to the above method embodiments, this application also provides a control device for a photovoltaic-storage-grid-connected off-grid air conditioning system. The photovoltaic-storage-grid-connected off-grid air conditioning system includes a photovoltaic air conditioner, a photovoltaic system, and an energy storage system. The photovoltaic air conditioner, photovoltaic system, and energy storage system are all connected to a DC bus. Figure 9 As shown, the device may include: a range determination module 901, a status acquisition module 902, and a linkage control module 903.

[0110] The range determination module 901 is used to obtain the current time and determine the time range to which the current time belongs when the photovoltaic storage and off-grid air conditioning system is in off-grid mode. The status acquisition module 902 is used to acquire the state of charge of the energy storage system. The linkage control module 903 is used to perform linkage control on the photovoltaic air conditioner, photovoltaic system and energy storage system according to the time range and the state of charge of the energy storage system.

[0111] This application also provides a photovoltaic air conditioner, such as... Figure 10 As shown, it includes a processor 1001, a communication interface 1002, a memory 1003, and a communication bus 1004, wherein the processor 1001, the communication interface 1002, and the memory 1003 communicate with each other through the communication bus 1004. Memory 1003 is used to store computer programs; When processor 1001 executes a program stored in memory 1003, it performs the following steps: When the photovoltaic-storage-off-grid air conditioning system is in off-grid mode, the current time is obtained and the time range to which the current time belongs is determined; the state of charge of the energy storage system is obtained; and the photovoltaic air conditioning, photovoltaic system and energy storage system are linked and controlled according to the time range and the state of charge of the energy storage system.

[0112] The communication bus mentioned in the photovoltaic air conditioner diagram can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. This communication bus can be divided into address bus, data bus, and control bus. For ease of representation, only one thick line is used in the diagram, but this does not indicate that there is only one bus or one type of bus.

[0113] The communication interface is used for communication between the aforementioned photovoltaic air conditioner and other devices.

[0114] The memory may include random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0115] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0116] In another embodiment provided in this application, a storage medium is also provided, which stores instructions that, when run on a computer, cause the computer to execute the control method of the optical storage and off-grid air conditioning system described in any of the above embodiments.

[0117] In another embodiment provided in this application, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to execute the control method of the optical storage and off-grid air conditioning system described in any of the above embodiments.

[0118] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a storage medium or transmitted from one storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid state disk (SSD)).

[0119] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0120] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0121] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application are included within the scope of protection of this application.

Claims

1. A control method for a photovoltaic-storage-off-grid air conditioning system, characterized in that, The photovoltaic-storage-connected off-grid air conditioning system includes a photovoltaic air conditioner, a photovoltaic system, and an energy storage system. The photovoltaic air conditioner, the photovoltaic system, and the energy storage system are all connected to a DC bus. The method includes: When the photovoltaic storage and off-grid air conditioning system is in off-grid mode, obtain the current time and determine the time range to which the current time belongs; Obtain the state of charge of the energy storage system; Based on the time range and the state of charge of the energy storage system, the photovoltaic air conditioner, the photovoltaic system, and the energy storage system are controlled in a coordinated manner.

2. The method according to claim 1, characterized in that, The photovoltaic-storage-off-grid air conditioning system also includes an auxiliary power supply, which is connected to the photovoltaic system. Before obtaining the current time, the system further includes: When the photovoltaic system is ready to generate electricity, the auxiliary power supply is started to supply power to the photovoltaic-storage-off-grid air conditioning system, so that the photovoltaic-storage-off-grid air conditioning system is ready to start and operate. During the operation of the photovoltaic system, the DC bus voltage is always stabilized through the energy storage system.

3. The method according to claim 1, characterized in that, The step of coordinating control of the photovoltaic air conditioner, the photovoltaic system, and the energy storage system based on the time range and the state of charge of the energy storage system includes: When the time range is the first time range, the following linkage control is performed on the photovoltaic air conditioner, the photovoltaic system, and the energy storage system: If the photovoltaic air conditioner is turned on, detect whether the state of charge of the energy storage system is greater than a preset first threshold. When the state of charge of the energy storage system is greater than a preset first threshold, the photovoltaic system and the energy storage system are controlled to jointly drive the photovoltaic air conditioner to operate; When the state of charge of the energy storage system is less than or equal to a preset first threshold, the photovoltaic system and the energy storage system are controlled to jointly drive the operation of the photovoltaic air conditioner, and the compressor frequency of the photovoltaic air conditioner is gradually reduced to reduce the power supply of the energy storage system until the power generation of the photovoltaic system and the power consumption of the photovoltaic air conditioner reach a balance, and the energy storage system stops supplying power. If the photovoltaic air conditioner is not turned on, check whether the state of charge of the energy storage system is less than a preset second threshold. When the state of charge of the energy storage system is less than a preset second threshold, the photovoltaic system is controlled to charge the energy storage system. When the state of charge of the energy storage system reaches a preset second threshold, the photovoltaic system is controlled to stop generating electricity.

4. The method according to claim 1, characterized in that, The step of coordinating control of the photovoltaic air conditioner, the photovoltaic system, and the energy storage system based on the time range and the state of charge of the energy storage system includes: When the time range is the second time range, the following linkage control is performed on the photovoltaic air conditioner, the photovoltaic system, and the energy storage system: If the power supply of the photovoltaic system is greater than the power consumption of the photovoltaic air conditioner, the state of charge of the energy storage system is detected to be less than a preset second threshold. When the state of charge of the energy storage system is less than a preset second threshold, the surplus electrical energy of the photovoltaic system is used to charge the energy storage system. If the power supply of the photovoltaic system is less than the power consumption of the photovoltaic air conditioner, the photovoltaic system and the energy storage system are controlled to jointly drive the operation of the photovoltaic air conditioner, and the compressor frequency of the photovoltaic air conditioner is gradually reduced, and the power supply of the energy storage system is reduced until the power generation of the photovoltaic system and the power consumption of the photovoltaic air conditioner reach a balance, and the energy storage system stops supplying power. If the power supply of the photovoltaic system is equal to the power consumption of the photovoltaic air conditioner, only the photovoltaic system is controlled to drive the photovoltaic air conditioner to operate, maintaining the current compressor frequency of the photovoltaic air conditioner.

5. The method according to claim 1, characterized in that, The step of coordinating control of the photovoltaic air conditioner, the photovoltaic system, and the energy storage system based on the time range and the state of charge of the energy storage system includes: When the time range is the third time range, the following linkage control is performed on the photovoltaic air conditioner, the photovoltaic system, and the energy storage system: The photovoltaic system and the energy storage system are controlled to jointly drive the operation of the photovoltaic air conditioner, and the compressor frequency of the photovoltaic air conditioner is gradually reduced until the power generation of the photovoltaic system approaches the preset power threshold, the compressor frequency of the photovoltaic air conditioner drops to the preset frequency threshold, and the photovoltaic-storage-off-grid air conditioning system shuts down. In the process of gradually reducing the compressor frequency of the photovoltaic air conditioner, the state of charge of the energy storage system is detected in real time to see if it is less than a preset third threshold. When the state of charge of the energy storage system is less than a preset third threshold, the compressor of the photovoltaic air conditioner is turned off, the photovoltaic-storage-off-grid air conditioning system is shut down, and the photovoltaic system is controlled to charge the energy storage system until the power generation of the photovoltaic system approaches the preset power threshold.

6. The method according to claim 3, characterized in that, The gradual reduction of the compressor frequency of the photovoltaic air conditioner includes: Real-time monitoring of the state of charge of the energy storage system, and finding the step interval where the state of charge of the energy storage system is located; Obtain the first frequency reduction step size corresponding to the stepped interval, and gradually reduce the compressor frequency of the photovoltaic air conditioner according to the first frequency reduction step size; or, The real-time light intensity is obtained by the irradiance sensor of the photovoltaic system, and the light intensity range in which the real-time light intensity is located is found. Obtain the second frequency reduction step size corresponding to the light intensity range, and gradually reduce the compressor frequency of the photovoltaic air conditioner according to the second frequency reduction step size.

7. The method according to claim 4, characterized in that, The gradual reduction of the compressor frequency of the photovoltaic air conditioner includes: Obtain the power difference between the power supplied by the photovoltaic system and the power consumed by the photovoltaic air conditioner; Find the third frequency reduction step size corresponding to the power difference, and gradually reduce the compressor frequency of the photovoltaic air conditioner according to the third frequency reduction step size; or, Obtain a fixed base frequency reduction step size and determine the rate of decrease in the replenishment power of the energy storage system; Find the correction step size corresponding to the rate of decrease in the replenished power, and obtain the sum of the fixed base frequency reduction step size and the correction step size; The compressor frequency of the photovoltaic air conditioner is gradually reduced according to the sum of the fixed base frequency reduction step size and the correction step size.

8. The method according to claim 5, characterized in that, The gradual reduction of the compressor frequency of the photovoltaic air conditioner includes: The power generation attenuation rate of the photovoltaic system is calculated in real time, and a linear frequency reduction curve of the compressor frequency is fitted based on the attenuation rate. The compressor frequency of the photovoltaic air conditioner is gradually reduced according to the linear frequency reduction curve of the compressor frequency. or, When the power generation of the photovoltaic system decays to the critical power generation threshold, the compressor frequency of the photovoltaic air conditioner is gradually reduced according to the basic frequency reduction step size; When the state of charge of the energy storage system reaches the critical state threshold, the compressor frequency of the photovoltaic air conditioner is gradually reduced according to the emergency frequency reduction step size; or, Predict the power supply duration of the photovoltaic system and divide the power supply duration into multiple sub-duration intervals; Determine the target sub-time interval in which the current moment is located from among the multiple sub-time intervals; The compressor frequency of the photovoltaic air conditioner is gradually reduced according to the frequency reduction step size corresponding to the target sub-duration interval; Among them, the frequency reduction step size corresponding to each of the sub-time intervals gradually increases.

9. A control device for a photovoltaic-storage-off-grid air conditioning system, characterized in that, The photovoltaic-storage-connected off-grid air conditioning system includes a photovoltaic air conditioner, a photovoltaic system, and an energy storage system. The photovoltaic air conditioner, the photovoltaic system, and the energy storage system are all connected to a DC bus. The device includes: The range determination module is used to obtain the current time and determine the time range to which the current time belongs when the photovoltaic storage and off-grid air conditioning system is in off-grid mode; A state acquisition module is used to acquire the state of charge of the energy storage system. The linkage control module is used to perform linkage control on the photovoltaic air conditioner, the photovoltaic system and the energy storage system according to the time range and the state of charge of the energy storage system.

10. A photovoltaic air conditioner, characterized in that, It includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; Memory, used to store computer programs; A processor, when executing a program stored in memory, implements the method described in any one of claims 1-8.

11. A storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1-8.

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