Photovoltaic air conditioning system and control method and control apparatus therefor

Abstract

Disclosed in the present invention are a photovoltaic air conditioning system and a control method and control apparatus therefor, which solve the technical problem of unstable operation of existing photovoltaic air conditioning systems. The control method comprises: acquiring real-time output power of a photovoltaic module in the photovoltaic air conditioning system and real-time required power of an air conditioning load; when the photovoltaic air conditioning system is in an off-grid state and the real-time output power of the photovoltaic module is less than the real-time required power of the air conditioning load, sequentially executing the following first control process and second control process, wherein the first control process comprises: determining a first target rotation speed on the basis of a real-time direct current bus voltage of the photovoltaic air conditioning system, and controlling, on the basis of the first target rotation speed, an air conditioner compressor to operate; and the second control process comprises: when the first control process ends, determining a second target rotation speed on the basis of the real-time output power of the photovoltaic module and the real-time required power of the air conditioner load, and controlling, on the basis of the second target rotation speed, the air conditioner compressor to operate.

Description

Photovoltaic air conditioning system and its control method and control device Technical Field

[0001] This invention belongs to the field of energy-saving air treatment technology, specifically, it relates to photovoltaic air conditioning systems and their control methods and devices. Background Technology

[0002] As an energy-saving air conditioning system, photovoltaic air conditioning systems have been widely applied in various fields such as production and daily life due to the increasingly urgent need for energy conservation and emission reduction and the continuous maturation of photovoltaic technology.

[0003] To meet users' air conditioning needs while maximizing the use of solar energy, photovoltaic (PV) air conditioning systems typically operate in a hybrid mode when the grid is supplying power normally, with both the grid and PV modules simultaneously powering the system. When the grid is interrupted, the PV system is in an off-grid state, powered solely by the PV modules. When the power provided by the PV modules is insufficient to meet the system's power requirements, the system often experiences synchronization issues or shutdowns, leading to instability and affecting its usability. Technical issues

[0004] The purpose of this invention is to provide a control method and control device for a photovoltaic air conditioning system, so as to improve the operational stability of the photovoltaic air conditioning system. Technical solutions

[0005] To achieve the above-mentioned objectives, the control method for the photovoltaic air conditioning system provided by this invention adopts the following technical solution:

[0006] A control method for a photovoltaic air conditioning system, comprising:

[0007] Obtain the real-time output power of the photovoltaic modules and the real-time power demand of the air conditioning load in the photovoltaic air conditioning system.

[0008] When the photovoltaic air conditioning system is in an off-grid state and the real-time output power of the photovoltaic module is less than the real-time demand power of the air conditioning load, the following first control process and second control process are executed in sequence.

[0009] The first control process includes: determining a first target speed based on the real-time DC bus voltage of the photovoltaic air conditioning system, and controlling the operation of the air conditioning compressor based on the first target speed, so that the operation of the air conditioner follows the change of the DC bus voltage;

[0010] The second control process includes: after the first control process is completed, determining a second target speed based on the real-time output power of the photovoltaic module and the real-time power demand of the air conditioning load, and controlling the operation of the air conditioning compressor based on the second target speed so that the operation of the air conditioning follows the changes in power supply and demand.

[0011] In some embodiments of this application, the first target rotational speed is determined based on the real-time DC bus voltage of the photovoltaic air conditioning system, specifically including:

[0012] The difference between the given DC bus voltage and the real-time DC bus voltage is obtained as the bus voltage deviation;

[0013] The bus voltage deviation is processed to obtain the first compensation rotational speed;

[0014] The difference between the given rotational speed and the first compensation rotational speed is obtained as the rotational speed after the first compensation.

[0015] The first compensated rotational speed is determined as the first target rotational speed.

[0016] In some embodiments of this application, controlling the operation of the air conditioning compressor based on the first target rotation speed specifically includes:

[0017] The first compensation rotation speed is processed to obtain the first rotation speed adjustment step size;

[0018] Obtain the real-time speed of the air conditioner compressor and compare it with the first target speed;

[0019] When the real-time speed is less than or equal to the first target speed, the real-time speed is used as the base speed, and the first speed adjustment step size is used as the speed adjustment step size to increase the real-time speed to obtain the first actual speed. The air conditioning compressor is controlled to run with the first actual speed until the first actual speed increases to the first target speed.

[0020] When the real-time speed is greater than the first target speed, the real-time speed is used as the base speed, and the first speed adjustment step size is used as the speed adjustment step size to reduce the real-time speed to obtain the second actual speed. The air conditioning compressor is controlled to run at the second actual speed until the second actual speed is reduced to the first target speed.

[0021] In some embodiments of this application, the first compensation rotation speed is processed to obtain a first rotation speed adjustment step size, specifically including:

[0022] The calculation result is obtained by performing a proportional calculation or a proportional-integral calculation on the first compensation rotation speed;

[0023] The calculation result is subjected to amplitude limiting processing to obtain the first speed adjustment step size.

[0024] In some embodiments of this application, the second target rotational speed is determined based on the real-time output power of the photovoltaic module and the real-time power demand of the air conditioning load, specifically including:

[0025] The difference between the real-time power demand of the air conditioning load and the real-time output power of the photovoltaic module is obtained as the power deviation;

[0026] The power deviation is processed to obtain the second compensation speed;

[0027] The difference between the given rotational speed and the second compensation rotational speed is obtained as the second compensation rotational speed;

[0028] The second compensated rotational speed is determined as the second target rotational speed.

[0029] In some embodiments of this application, controlling the operation of the air conditioning compressor according to the second target speed specifically includes:

[0030] The second compensation speed is processed to obtain the second speed adjustment step size;

[0031] Obtain the real-time speed of the air conditioner compressor and compare it with the second target speed;

[0032] When the real-time speed is less than or equal to the second target speed, the real-time speed is used as the base speed, and the second speed adjustment step size is used as the speed adjustment step size to increase the real-time speed to obtain the third actual speed. The air conditioning compressor is controlled to run with the third actual speed until the third actual speed increases to the second target speed.

[0033] When the real-time speed is greater than the second target speed, the real-time speed is used as the base speed, and the second speed adjustment step size is used as the speed adjustment step size to reduce the real-time speed to obtain a fourth actual speed. The air conditioning compressor is controlled to run at the fourth actual speed until the fourth actual speed is reduced to the second target speed.

[0034] In some embodiments of this application, the second compensation rotation speed is processed to obtain a second rotation speed adjustment step size, specifically including:

[0035] The calculation result is obtained by performing a proportional calculation or a proportional-integral calculation on the second compensation rotation speed;

[0036] The calculation result is subjected to amplitude limiting processing to obtain the second speed adjustment step size.

[0037] In some embodiments of this application, the rotational speed is determined using the following process:

[0038] The system acquires the real-time temperature and humidity of the indoor environment where the photovoltaic air conditioning system is located, as well as the real-time fan speed of the indoor unit in the photovoltaic air conditioning system.

[0039] The real-time effective temperature index is determined based on the real-time temperature, the real-time humidity, and the real-time fan speed.

[0040] The difference between the given effective temperature index and the real-time effective temperature index is obtained as the effective temperature index deviation;

[0041] The effective temperature deviation is processed to obtain the given rotational speed.

[0042] To achieve the aforementioned objectives, the control device for the photovoltaic air conditioning system provided by this invention employs the following technical solution:

[0043] A control device for a photovoltaic air conditioning system, comprising:

[0044] A real-time output power acquisition unit for photovoltaic modules is used to acquire the real-time output power of photovoltaic modules in a photovoltaic air conditioning system.

[0045] The real-time power demand acquisition unit for air conditioning load is used to acquire the real-time power demand of the air conditioning load in the photovoltaic air conditioning system.

[0046] The control unit is used to execute the following first control process and second control process in sequence when the photovoltaic air conditioning system is in an off-grid state and the real-time output power of the photovoltaic module is less than the real-time demand power of the air conditioning load.

[0047] The first control process includes: determining a first target speed based on the real-time DC bus voltage of the photovoltaic air conditioning system, and controlling the operation of the air conditioning compressor based on the first target speed, so that the operation of the air conditioner follows the change of the DC bus voltage;

[0048] The second control process includes: after the first control process is completed, determining a second target speed based on the real-time output power of the photovoltaic module and the real-time power demand of the air conditioning load, and controlling the operation of the air conditioning compressor based on the second target speed so that the operation of the air conditioning follows the changes in power supply and demand.

[0049] Another object of the present invention is to provide a photovoltaic air conditioning system, including a photovoltaic module and an air conditioner, wherein the photovoltaic air conditioning system further includes the control device of the photovoltaic air conditioning system described above. Beneficial effects

[0050] Compared with the prior art, the advantages and positive effects of the present invention are:

[0051] The photovoltaic air conditioning system, its control method, and control device provided by this invention, when the photovoltaic air conditioning system is in an off-grid state (power outage), is powered by photovoltaic modules. When the real-time output power of the photovoltaic modules is less than the real-time power demand of the air conditioning load, a first target speed is first determined based on the real-time DC bus voltage of the photovoltaic air conditioning system. The air conditioning compressor is then controlled to operate at this first target speed, ensuring that the air conditioning operation follows the changes in DC bus voltage. Because the DC bus voltage changes significantly after the photovoltaic grid is de-energized, adjusting the target speed of the air conditioning compressor based on the DC bus voltage first allows for a rapid response to the power supply status and ensures stable operation of the air conditioning. Then, a second target speed is determined based on the real-time output power of the photovoltaic modules and the real-time power demand of the air conditioning load. The air conditioning compressor is then controlled to operate at the second target speed, ensuring that the air conditioning operation follows the changes in power supply and demand. This avoids overshoot due to excessively rapid compressor speed adjustment, which could affect the stable operation of the air conditioning. Therefore, by using two different control processes to adjust the compressor speed in stages when the photovoltaic air conditioning system is off-grid, the continuous operational stability of the photovoltaic air conditioning system can be improved, ensuring the usability of the air conditioning system.

[0052] Other features and advantages of the present invention will become clearer after reading the detailed embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0054] Figure 1 is a flowchart of the first embodiment of the control method of the photovoltaic air conditioning system of the present invention;

[0055] Figure 2 is a flowchart of the second embodiment of the control method of the photovoltaic air conditioning system of the present invention;

[0056] Figure 3 is a flowchart of the third embodiment of the control method of the photovoltaic air conditioning system of the present invention;

[0057] Figure 4 is a flowchart of the fourth embodiment of the control method of the photovoltaic air conditioning system of the present invention;

[0058] Figure 5 is a flowchart of the fifth embodiment of the control method for the photovoltaic air conditioning system of the present invention;

[0059] Figure 6 is a schematic diagram of the structure of a control device for the photovoltaic air conditioning system of the present invention. Embodiments of the present invention

[0060] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0061] It should be noted that the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they can be implemented by those skilled in the art. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0062] Figure 1 shows a flowchart of the first embodiment of the control method for the photovoltaic air conditioning system of the present invention. In this embodiment, the photovoltaic air conditioning system includes photovoltaic modules and an air conditioner, which can be powered by the power grid and / or the photovoltaic modules. The control method of this embodiment includes:

[0063] S11: Determine the conditions that the photovoltaic air conditioning system is in an off-grid state and the real-time output power of the photovoltaic modules is less than the real-time demand power of the air conditioning load.

[0064] In this embodiment, it is necessary to obtain the real-time output power of the photovoltaic modules in the photovoltaic air conditioning system and the real-time demand power of the air conditioning load.

[0065] The real-time output power of the photovoltaic (PV) module is the output power of the PV module acquired in real time according to a set sampling period. The real-time power demand of the air conditioning load is the power demand of the air conditioning load acquired in real time according to a set sampling period. The real-time output power of the PV module can be acquired using related technologies, and this embodiment does not limit the specific acquisition method. In some embodiments, the real-time output power of the PV module is acquired based on the real-time output voltage and real-time output current of the PV module. In other embodiments, the real-time output power of the PV module is acquired based on predictions from a PV module power generation prediction model. The real-time power demand of the air conditioning load can be acquired using related technologies, and this embodiment does not limit the specific acquisition method. In some embodiments, the real-time power demand of the air conditioning load is acquired based on predictions from an air conditioning load prediction model. In other embodiments, the real-time power demand of the air conditioning load is calculated based on the real-time temperature and set temperature of the indoor environment where the air conditioner is located.

[0066] In this embodiment, the grid status is also monitored in real time, and when the grid is interrupted, it is determined that the photovoltaic air conditioning system is in an off-grid state. In the off-grid state, the photovoltaic modules will supply power to the photovoltaic air conditioning system independently. Furthermore, in the off-grid state, the real-time output power of the photovoltaic modules is compared with the real-time power demand of the air conditioning load to determine whether the real-time output power of the photovoltaic modules is less than the real-time power demand of the air conditioning load.

[0067] If the real-time output power of the photovoltaic module is less than the real-time power demand of the air conditioning load, it indicates that the power provided by the photovoltaic module cannot meet the power requirements of the air conditioning system. To ensure the use of the air conditioning, it is necessary to control the air conditioning to reduce its actual operating power. Moreover, to ensure the stability of the air conditioning during reduced power operation, this embodiment uses two different control processes, S12 and S13, as described below, to control the air conditioning.

[0068] S12: Under the condition that the photovoltaic air conditioning system is in an off-grid state and the real-time output power of the photovoltaic modules is less than the real-time demand power of the air conditioning load, the first control process is executed first. The first target speed is determined according to the real-time DC bus voltage of the photovoltaic air conditioning system. The air conditioning compressor is controlled to run according to the first target speed, so that the operation of the air conditioner follows the change of the DC bus voltage.

[0069] The real-time DC bus voltage is the DC bus voltage of the photovoltaic air conditioning system that is acquired in real time according to a set sampling period. The acquisition method can be implemented using relevant technologies, and this embodiment does not limit the specific acquisition method.

[0070] This embodiment does not limit the specific implementation method of determining the first target speed based on the real-time DC bus voltage of the photovoltaic air conditioning system. All implementation methods that enable the air conditioner to operate in accordance with the changes in the DC bus voltage to maintain stable operation of the air conditioner are within the protection scope of this invention.

[0071] S13: After the first control process is completed, the second control process is executed. The second target speed is determined based on the real-time output power of the photovoltaic module and the real-time power demand of the air conditioning load. The operation of the air conditioning compressor is controlled according to the second target speed so that the operation of the air conditioning changes with the power supply and demand.

[0072] This embodiment does not limit the specific implementation of determining the second target rotation speed based on the real-time output power of the photovoltaic module and the real-time power demand of the air conditioning load. All implementation methods that enable the air conditioner to operate in accordance with changes in power supply and demand to maintain stable operation are within the scope of protection of this invention.

[0073] The method described in the above embodiment controls the photovoltaic air conditioning system. In the off-grid state, when the real-time output power of the photovoltaic modules is less than the real-time power demand of the air conditioning load, a first target speed is first determined based on the real-time DC bus voltage of the photovoltaic air conditioning system. The air conditioning compressor is then controlled to operate at this first target speed, ensuring that the air conditioning operation follows the changes in DC bus voltage. Because the DC bus voltage changes significantly after the photovoltaic grid is de-energized, adjusting the target speed of the air conditioning compressor based on the DC bus voltage first allows for a rapid response to the power supply status and ensures stable operation of the air conditioning. Then, a second target speed is determined based on the real-time output power of the photovoltaic modules and the real-time power demand of the air conditioning load. The air conditioning compressor is then controlled to operate at the second target speed, ensuring that the air conditioning operation follows the changes in power supply and demand. This avoids overshoot due to excessively rapid compressor speed adjustment, which could affect the stable operation of the air conditioning. Therefore, by using two different control processes to adjust the compressor speed in stages when the photovoltaic air conditioning system is off-grid, the continuous operational stability of the photovoltaic air conditioning system can be improved, ensuring the usability of the air conditioning system.

[0074] In some other embodiments, in the off-grid state, if the real-time output power of the photovoltaic module is not less than the real-time power demand of the air conditioning load, it indicates that the power provided by the photovoltaic module is sufficient and the air conditioning is operating normally and stably at the real-time power demand.

[0075] In some other embodiments, the first control process is determined to have ended in the following manner: if the compressor operates at the first target speed for a set duration, the first control process is determined to have ended; otherwise, the first control process is determined to have not yet ended.

[0076] Figure 2 shows a flowchart of a second embodiment of the control method for the photovoltaic air conditioning system of the present invention. In this embodiment, the photovoltaic air conditioning system includes photovoltaic modules and an air conditioner. When the photovoltaic air conditioning system is in an off-grid state and the real-time output power of the photovoltaic modules is less than the real-time power demand of the air conditioning load, the air conditioner is controlled sequentially using the first control process and the second control process of the embodiment in Figure 1. In the first control process, a first target speed is determined based on the real-time DC bus voltage of the air conditioning system, and the air conditioning compressor is controlled to operate based on the first target speed. Moreover, the first target speed is determined using the following process.

[0077] S21: Obtain the difference between the given DC bus voltage and the real-time DC bus voltage as the bus voltage deviation.

[0078] Among them, the given DC bus voltage is known, and the real-time DC bus voltage is available.

[0079] S22: Process the bus voltage deviation to obtain the first compensation speed.

[0080] The first compensation rotational speed is determined based on the bus voltage deviation and changes with the bus voltage deviation. This embodiment does not limit the specific method for determining the first compensation rotational speed. In some embodiments, the bus voltage deviation is processed by proportional-integral processing to obtain the first compensation rotational speed.

[0081] S23: Obtain the difference between the given rotational speed and the rotational speed for first compensation, and use it as the rotational speed after first compensation. Then, determine the rotational speed after first compensation as the first target rotational speed.

[0082] The rotational speed is known. In some embodiments, the rotational speed is a set value, which is a fixed value.

[0083] In some other embodiments, the rotational speed is given as a variable value.

[0084] In some other embodiments, the rotational speed is a dynamically variable value that follows temperature, humidity, and the fan speed of the indoor unit of the air conditioner, and the rotational speed is determined using the following process:

[0085] The system acquires the real-time temperature and humidity of the indoor environment where the photovoltaic air conditioning system is located, as well as the real-time fan speed of the indoor unit in the photovoltaic air conditioning system.

[0086] The real-time effective temperature index is determined based on real-time temperature, real-time humidity, and real-time fan speed. The specific determination method is not limited and can be implemented using relevant technologies.

[0087] The difference between the given effective temperature index and the real-time effective temperature index is obtained as the effective temperature index deviation. The given effective temperature index is known.

[0088] The effective temperature deviation is processed to obtain the rotational speed setpoint. The rotational speed setpoint changes with the effective temperature deviation, and this embodiment does not limit the specific determination method. In some embodiments, the rotational speed setpoint is obtained by performing proportional-integral processing on the effective temperature deviation.

[0089] By determining the real-time effective temperature index based on real-time temperature, real-time humidity, and real-time fan speed, and then determining the speed setpoint based on the real-time effective temperature index, the speed setpoint is matched with the real-time indoor environment. The target speed of the compressor is then determined based on the speed setpoint, and the compressor is controlled to run at the target speed. This adapts to the real-time indoor environment and improves the comfort of the air conditioner's indoor environment regulation.

[0090] Figure 3 shows a flowchart of a third embodiment of the control method for the photovoltaic air conditioning system of the present invention. In this embodiment, the photovoltaic air conditioning system includes photovoltaic modules and an air conditioner. When the photovoltaic air conditioning system is in an off-grid state, and the real-time output power of the photovoltaic modules is less than the real-time power demand of the air conditioning load, the air conditioner is controlled sequentially using the first and second control processes described in the aforementioned embodiments. In the first control process, a first target speed is determined based on the real-time DC bus voltage of the aforementioned air conditioning system, and the air conditioning compressor is controlled to operate based on the first target speed. Furthermore, the specific process of controlling the air conditioning compressor to operate based on the first target speed is as follows.

[0091] S31: Process the first compensation speed to obtain the first speed adjustment step size.

[0092] The method for obtaining the rotational speed for the first compensation is described in the above embodiment.

[0093] The first speed adjustment step size changes with the change of the first compensation speed, and this embodiment does not limit the specific determination method.

[0094] In some embodiments, a proportional or proportional-integral operation is performed on the first compensation speed to obtain the calculation result; then, the calculation result is subjected to amplitude limiting processing to obtain the first compensation speed. Amplitude limiting processing of the calculation result includes limiting the maximum value and limiting the minimum value of the calculation result. Obtaining the first compensation speed by amplitude limiting the calculation result avoids the first compensation speed being too large or too small, which could affect the operational stability during subsequent air conditioning control.

[0095] S32: Obtain the real-time speed of the air conditioner and compare it with the first target speed.

[0096] The method for obtaining the first target speed is described in the above embodiment. The real-time speed of the air conditioner is the speed of the air conditioner compressor, which is obtained in real time according to a set sampling period.

[0097] S33: Based on the comparison results, combined with the real-time speed, the first speed adjustment step size, and the first target speed, control the operation of the air conditioning compressor.

[0098] Specifically, if the real-time speed is less than or equal to the first target speed, the compressor speed is increased. Furthermore, when increasing the speed, the real-time speed is used as the base speed, with a first speed adjustment step size as the speed adjustment step size. The real-time speed is increased to obtain the first actual speed, and the air conditioning compressor is controlled to operate at this first actual speed until the first actual speed reaches the first target speed, at which point speed adjustment stops. It should be understood that the first actual speed obtained by increasing the current real-time speed by the first speed adjustment step size will be used as the real-time speed for the next speed adjustment. The next first actual speed will be obtained by further increasing the first speed adjustment step size on top of this. For example, the first real-time speed is denoted as N. up The first speed adjustment step size is denoted as N. a1 The first actual rotational speed is denoted as N. n1 Then we have: N n1 = N up +i×N a1 , where i is a natural number, representing the number of adjustments.

[0099] If the real-time speed is greater than the first target speed, the compressor speed is controlled to decrease. Furthermore, during speed reduction, the real-time speed is used as the base speed, with a first speed adjustment step size as the speed adjustment step size. The real-time speed is then reduced to obtain a second actual speed, which is used to control the air conditioning compressor until the second actual speed decreases to the first target speed. Similarly, the second actual speed obtained by reducing the first speed adjustment step size from the current real-time speed will be used as the real-time speed for the next speed adjustment. The first speed adjustment step size is then further reduced from this second actual speed to obtain the next second actual speed. For example, let the first real-time speed be denoted as N. down The first speed adjustment step size is denoted as N. a1 The second actual rotational speed is denoted as N. n2 Then we have: N n2 = N down -j×N a1 j is a natural number, representing the number of adjustments.

[0100] In the above embodiment, the first speed adjustment step size is dynamically determined based on the first compensation speed, which in turn is dynamically determined based on the bus voltage deviation. The bus voltage deviation is further dynamically determined based on the given DC bus voltage and the real-time DC bus voltage. Since the real-time DC bus voltage is not a fixed value, the final determined first speed adjustment step size is also not a fixed value. Based on this non-fixed first speed adjustment step size, the air conditioning compressor speed is dynamically adjusted, gradually increasing or decreasing, enabling the air conditioning compressor speed to adapt to changes in different operating conditions of the photovoltaic air conditioning system, effectively solving the problem of unstable air conditioning operation caused by sudden changes in DC bus voltage.

[0101] Figure 4 shows a flowchart of a fourth embodiment of the control method for the photovoltaic air conditioning system of the present invention. In this embodiment, the photovoltaic air conditioning system includes photovoltaic modules and an air conditioner. When the photovoltaic air conditioning system is in an off-grid state and the real-time output power of the photovoltaic modules is less than the real-time power demand of the air conditioning load, the air conditioner is controlled sequentially using the first control process and the second control process of the embodiment in Figure 1. In the second control process, a second target speed is determined based on the real-time output power of the photovoltaic modules and the real-time power demand of the air conditioning load, and the air conditioning compressor is controlled to operate based on the second target speed. Moreover, the second target speed is determined using the following process.

[0102] S41: Obtain the difference between the real-time power demand of the air conditioning load and the real-time output power of the photovoltaic module as the power deviation.

[0103] The real-time power demand of the air conditioning load and the real-time output power of the photovoltaic module are both available, and the acquisition method is described in the above embodiment.

[0104] S42: Process the power deviation to obtain the second compensation speed.

[0105] The second compensation speed is determined based on the power deviation and changes with the power deviation. This embodiment does not limit the specific method for determining the second compensation speed. In some embodiments, the power deviation is processed by proportional-integral processing to obtain the second compensation speed.

[0106] S43: Obtain the difference between the given rotational speed and the rotational speed for second compensation, and use it as the second compensated rotational speed. Then, determine the second compensated rotational speed as the second target rotational speed.

[0107] The rotational speed is known. In some embodiments, the rotational speed is a set value, which is a fixed value.

[0108] In some other embodiments, the rotational speed is given as a variable value.

[0109] In some other embodiments, the rotational speed is a dynamically variable value that follows temperature, humidity, and the fan speed of the indoor unit of the air conditioner, and the rotational speed is determined using the following process:

[0110] The system acquires the real-time temperature and humidity of the indoor environment where the photovoltaic air conditioning system is located, as well as the real-time fan speed of the indoor unit in the photovoltaic air conditioning system.

[0111] The real-time effective temperature index is determined based on real-time temperature, real-time humidity, and real-time fan speed. The specific determination method is not limited and can be implemented using relevant technologies.

[0112] The difference between the given effective temperature index and the real-time effective temperature index is obtained as the effective temperature index deviation. The given effective temperature index is known.

[0113] The effective temperature deviation is processed to obtain the rotational speed setpoint. The rotational speed setpoint changes with the effective temperature deviation, and this embodiment does not limit the specific determination method. In some embodiments, the rotational speed setpoint is obtained by performing proportional-integral processing on the effective temperature deviation.

[0114] By determining the real-time effective temperature index based on real-time temperature, real-time humidity, and real-time fan speed, and then determining the speed setpoint based on the real-time effective temperature index, the speed setpoint is matched with the real-time indoor environment. The target speed of the compressor is then determined based on the speed setpoint, and the compressor is controlled to run at the target speed. This adapts to the real-time indoor environment and improves the comfort of the air conditioner's indoor environment regulation.

[0115] Figure 5 shows a flowchart of a fifth embodiment of the control method for the photovoltaic air conditioning system of the present invention. In this embodiment, the photovoltaic air conditioning system includes photovoltaic modules and an air conditioner. When the photovoltaic air conditioning system is in an off-grid state and the real-time output power of the photovoltaic modules is less than the real-time power demand of the air conditioning load, the air conditioner is controlled sequentially using the first and second control processes described in the previous embodiments. In the second control process, a second target speed is determined based on the real-time output power of the photovoltaic modules and the real-time power demand of the air conditioning load, and the air conditioning compressor is controlled to operate according to the second target speed. The specific process of controlling the air conditioning compressor to operate according to the second target speed is as follows.

[0116] S51: Process the second compensation speed to obtain the second speed adjustment step size.

[0117] The method for obtaining the rotational speed for the second compensation is described in the above embodiment.

[0118] The second speed adjustment step size changes in accordance with the change of the second compensation speed. This embodiment does not limit the specific determination method.

[0119] In some embodiments, a proportional or proportional-integral operation is performed on the second compensation speed to obtain the calculation result; then, the calculation result is subjected to amplitude limiting processing to obtain the second compensation speed. Amplitude limiting processing of the calculation result includes limiting the maximum value and limiting the minimum value of the calculation result. Obtaining the second compensation speed by amplitude limiting the calculation result avoids the second compensation speed being too large or too small, which could affect the operational stability during subsequent air conditioning control.

[0120] S52: Obtain the real-time speed of the air conditioner and compare it with the second target speed.

[0121] The method for obtaining the second target rotational speed is described in the above embodiment. The real-time rotational speed of the air conditioner is the rotational speed of the air conditioner compressor, which is obtained in real time according to a set sampling period.

[0122] S53: Based on the comparison results, combined with the real-time speed, the second speed adjustment step size, and the second target speed, control the operation of the air conditioning compressor.

[0123] When the real-time speed is less than or equal to the second target speed, the compressor speed is increased. Furthermore, during the speed increase, the real-time speed is used as the base speed, with the second speed adjustment step size as the speed adjustment step size. The real-time speed is increased to obtain a third actual speed, which is then used to control the air conditioning compressor until the third actual speed reaches the second target speed, at which point speed adjustment stops. It should be understood that the third actual speed obtained by increasing the current real-time speed by the second speed adjustment step size will be used as the real-time speed for the next speed adjustment. The second speed adjustment step size will then be increased again to obtain the next third actual speed. For example, the first real-time speed is still denoted as N. up The second speed adjustment step size is denoted as N. a2 The third actual rotational speed is denoted as N. n3 Then we have: N n3 = N up +k×N a2 k is a natural number, representing the number of adjustments.

[0124] If the real-time speed is greater than the second target speed, the compressor speed is controlled to decrease. Furthermore, during speed reduction, the real-time speed is used as the base speed, with the second speed adjustment step size as the speed adjustment step size. The real-time speed is then reduced to obtain a fourth actual speed, which is used to control the air conditioning compressor until the fourth actual speed decreases to the second target speed. Similarly, the fourth actual speed obtained by reducing the second speed adjustment step size from the current real-time speed will be used as the real-time speed for the next speed adjustment. The second speed adjustment step size is then further reduced from this fourth actual speed to obtain the next fourth actual speed. For example, the first real-time speed is still denoted as N. down The second speed adjustment step size is denoted as N. a2 The fourth actual rotational speed is denoted as N. n4 Then we have: N n4 = N down -m×N a2 , where m is a natural number and represents the number of adjustments.

[0125] In the above embodiment, the second speed adjustment step size is dynamically determined based on the second compensation speed, which in turn is dynamically determined based on the power deviation. The power deviation is further dynamically determined based on the real-time power demand of the air conditioning load and the real-time output power of the photovoltaic module. Since the real-time power demand of the air conditioning load and the real-time output power of the photovoltaic module are typically non-fixed values, the final determined second speed adjustment step size is also non-fixed. Based on this non-fixed second speed adjustment step size, the air conditioning compressor speed is dynamically adjusted, gradually increasing or decreasing, allowing the compressor speed to adapt to changes in different operating conditions of the photovoltaic air conditioning system. This effectively solves the problem of unstable air conditioning operation caused by sudden changes in the power demand of the air conditioning load and / or the output power of the photovoltaic module.

[0126] Figure 6 shows a schematic diagram of a control device for a photovoltaic air conditioning system according to an embodiment of the present invention. In this embodiment, the photovoltaic air conditioning system includes photovoltaic modules and an air conditioner, which can be powered by the power grid and / or the photovoltaic modules. The structural units included in the control device of this embodiment, the functions of the structural units, and the relationships between them are as follows:

[0127] The control device includes:

[0128] The real-time output power acquisition unit 61 of the photovoltaic module is used to acquire the real-time output power of the photovoltaic module in the photovoltaic air conditioning system.

[0129] The real-time power demand acquisition unit 62 for air conditioning load is used to acquire the real-time power demand of the air conditioning load in the photovoltaic air conditioning system.

[0130] Control unit 63 is used to execute a first control process and a second control process when the photovoltaic air conditioning system is in an off-grid state and the real-time output power of the photovoltaic modules acquired by the real-time output power acquisition unit 61 is less than the real-time demand power of the air conditioning load acquired by the real-time demand power acquisition unit 62. The first control process includes: determining a first target speed based on the real-time DC bus voltage of the photovoltaic air conditioning system, and controlling the operation of the air conditioning compressor according to the first target speed, so that the operation of the air conditioner follows the changes in the DC bus voltage. The second control process includes: after the first control process ends, determining a second target speed based on the real-time output power of the photovoltaic modules and the real-time demand power of the air conditioning load, and controlling the operation of the air conditioning compressor according to the second target speed, so that the operation of the air conditioner follows the changes in power supply and demand.

[0131] The control device described above runs the corresponding software program, performs the corresponding functions, and controls the photovoltaic air conditioning system according to the control method embodiment of Figure 1 and other embodiments, so as to achieve the corresponding technical effects as the embodiment of Figure 1 and other embodiments.

[0132] The control devices described in the above embodiments are applied to photovoltaic air conditioning systems, which can improve the continuous operational stability of the photovoltaic air conditioning system and ensure the use of the air conditioning system.

[0133] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions claimed by the present invention.

Claims

1. A control method for a photovoltaic air conditioning system, characterized in that, The control method includes: Obtain the real-time output power of the photovoltaic modules and the real-time power demand of the air conditioning load in the photovoltaic air conditioning system. When the photovoltaic air conditioning system is in an off-grid state and the real-time output power of the photovoltaic module is less than the real-time demand power of the air conditioning load, the following first control process and second control process are executed in sequence. The first control process includes: determining a first target speed based on the real-time DC bus voltage of the photovoltaic air conditioning system, and controlling the operation of the air conditioning compressor based on the first target speed, so that the operation of the air conditioner follows the change of the DC bus voltage; The second control process includes: after the first control process is completed, determining a second target speed based on the real-time output power of the photovoltaic module and the real-time power demand of the air conditioning load, and controlling the operation of the air conditioning compressor based on the second target speed so that the operation of the air conditioning follows the changes in power supply and demand.

2. The control method for a photovoltaic air conditioning system according to claim 1, characterized in that, The first target rotational speed is determined based on the real-time DC bus voltage of the photovoltaic air conditioning system, specifically including: The difference between the given DC bus voltage and the real-time DC bus voltage is obtained as the bus voltage deviation; The bus voltage deviation is processed to obtain the first compensation rotational speed; The difference between the given rotational speed and the first compensation rotational speed is obtained as the rotational speed after the first compensation. The first compensated rotational speed is determined as the first target rotational speed.

3. The control method for the photovoltaic air conditioning system according to claim 2, characterized in that, Controlling the air conditioning compressor to operate according to the first target speed specifically includes: The first compensation rotation speed is processed to obtain the first rotation speed adjustment step size; Obtain the real-time speed of the air conditioner compressor and compare it with the first target speed; When the real-time speed is less than or equal to the first target speed, the real-time speed is used as the base speed, and the first speed adjustment step size is used as the speed adjustment step size to increase the real-time speed to obtain the first actual speed. The air conditioning compressor is controlled to run with the first actual speed until the first actual speed increases to the first target speed. When the real-time speed is greater than the first target speed, the real-time speed is used as the base speed, and the first speed adjustment step size is used as the speed adjustment step size to reduce the real-time speed to obtain the second actual speed. The air conditioning compressor is controlled to run at the second actual speed until the second actual speed is reduced to the first target speed.

4. The control method for the photovoltaic air conditioning system according to claim 3, characterized in that, The first compensation speed is processed to obtain the first speed adjustment step size, specifically including: The calculation result is obtained by performing a proportional calculation or a proportional-integral calculation on the first compensation rotation speed; The calculation result is subjected to amplitude limiting processing to obtain the first speed adjustment step size.

5. The control method for a photovoltaic air conditioning system according to claim 1, characterized in that, The second target rotational speed is determined based on the real-time output power of the photovoltaic module and the real-time power demand of the air conditioning load, specifically including: The difference between the real-time power demand of the air conditioning load and the real-time output power of the photovoltaic module is obtained as the power deviation; The power deviation is processed to obtain the second compensation speed; The difference between the given rotational speed and the second compensation rotational speed is obtained as the second compensation rotational speed; The second compensated rotational speed is determined as the second target rotational speed.

6. The control method for the photovoltaic air conditioning system according to claim 5, characterized in that, Controlling the air conditioning compressor operation according to the second target speed specifically includes: The second compensation speed is processed to obtain the second speed adjustment step size; Obtain the real-time speed of the air conditioner compressor and compare it with the second target speed; When the real-time speed is less than or equal to the second target speed, the real-time speed is used as the base speed, and the second speed adjustment step size is used as the speed adjustment step size to increase the real-time speed to obtain the third actual speed. The air conditioning compressor is controlled to run with the third actual speed until the third actual speed increases to the second target speed. When the real-time speed is greater than the second target speed, the real-time speed is used as the base speed, and the second speed adjustment step size is used as the speed adjustment step size to reduce the real-time speed to obtain a fourth actual speed. The air conditioning compressor is controlled to run at the fourth actual speed until the fourth actual speed is reduced to the second target speed.

7. The control method for a photovoltaic air conditioning system according to claim 6, characterized in that, The second compensation speed is processed to obtain the second speed adjustment step size, specifically including: The calculation result is obtained by performing a proportional calculation or a proportional-integral calculation on the second compensation rotation speed; The calculation result is subjected to amplitude limiting processing to obtain the second speed adjustment step size.

8. The control method for a photovoltaic air conditioning system according to claim 2 or 5, characterized in that, The given rotational speed is determined using the following process: The system acquires the real-time temperature and humidity of the indoor environment where the photovoltaic air conditioning system is located, as well as the real-time fan speed of the indoor unit in the photovoltaic air conditioning system. The real-time effective temperature index is determined based on the real-time temperature, the real-time humidity, and the real-time fan speed. The difference between the given effective temperature index and the real-time effective temperature index is obtained as the effective temperature index deviation; The effective temperature deviation is processed to obtain the given rotational speed.

9. A control device for a photovoltaic air conditioning system, characterized in that, The control device includes: A real-time output power acquisition unit for photovoltaic modules is used to acquire the real-time output power of photovoltaic modules in a photovoltaic air conditioning system. The real-time power demand acquisition unit for air conditioning load is used to acquire the real-time power demand of the air conditioning load in the photovoltaic air conditioning system. The control unit is used to execute the following first control process and second control process in sequence when the photovoltaic air conditioning system is in an off-grid state and the real-time output power of the photovoltaic module is less than the real-time demand power of the air conditioning load. The first control process includes: determining a first target speed based on the real-time DC bus voltage of the photovoltaic air conditioning system, and controlling the operation of the air conditioning compressor based on the first target speed, so that the operation of the air conditioner follows the change of the DC bus voltage; The second control process includes: after the first control process is completed, determining a second target speed based on the real-time output power of the photovoltaic module and the real-time power demand of the air conditioning load, and controlling the operation of the air conditioning compressor based on the second target speed so that the operation of the air conditioning follows the changes in power supply and demand.

10. A photovoltaic air conditioning system, comprising photovoltaic modules and an air conditioner, characterized in that, The photovoltaic air conditioning system also includes the control device for the photovoltaic air conditioning system as described in claim 9.

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