A photovoltaic air conditioning system bus voltage dynamic regulation method, a photovoltaic air conditioning system and a photovoltaic air conditioner

Abstract

The application provides a photovoltaic air conditioner system bus voltage dynamic regulation method, a photovoltaic air conditioner system and a photovoltaic air conditioner, and belongs to the technical field of household appliances. The method comprises the following steps: solving air conditioner power demand according to the compressor operating frequency, combining photovoltaic power generation power to determine the system state of the photovoltaic air conditioner; when the system state of the photovoltaic air conditioner is determined as an inversion mode, adjusting the bus voltage value to the maximum power output point through an MPPT algorithm; when the system state of the photovoltaic air conditioner system is determined as a rectification mode, setting the initial value of the bus voltage through a reinforcement learning algorithm, and optimizing the bus voltage to the target value of the bus voltage through a PID control algorithm. The air conditioner power demand adjusts the bus voltage to the optimal value in real time, ensures that the system can stably operate under different operating conditions, improves the overall stability and reliability of the system, and is suitable for the photovoltaic air conditioner system under various complex working conditions.

Description

Technical Field

[0001] This invention belongs to the field of household appliance technology, and more specifically, relates to a method for dynamic adjustment of bus voltage in a photovoltaic air conditioning system, a photovoltaic air conditioning system, and a photovoltaic air conditioner. Background Technology

[0002] Photovoltaic air conditioners are a combination of inverters and air conditioners. In order to make the two more flexible and dispatchable, dynamic control of the bus voltage is the key to the control of photovoltaic air conditioners.

[0003] Traditional control methods often set only a single primary control objective for the system, such as maximum power generation or stable power supply. If maximum power generation is consistently achieved using the MPPT (Maximum Power Point Tracking) mode, the bus voltage will fluctuate continuously due to tracking the MPPT point when photovoltaic power is insufficient. This fluctuation severely affects the power quality and stability of the power supplied by the downstream inverter to the air conditioning compressor, leading to unstable compressor operation, increased noise, or even shutdown. If a fixed bus voltage mode is consistently used to achieve stable power supply, the system cannot dynamically adjust its operating point when photovoltaic power is sufficient, making it unable to track the maximum power point of the photovoltaic array. This results in wasted photovoltaic energy and low system efficiency. The operating conditions of photovoltaic air conditioning systems are highly complex, with constantly changing light intensity and load demands. Fixed control strategies cannot adapt to this variability and are prone to system oscillations, slow response, or protective shutdowns during operating condition transitions.

[0004] Therefore, existing technologies cannot dynamically adjust and optimize based on real-time changes in energy supply and demand, and the system cannot always operate in a globally optimal state. Summary of the Invention

[0005] To address the system operation problems caused by fixed bus voltage settings in existing photovoltaic air conditioning systems, this invention provides a method for dynamically adjusting the bus voltage of a photovoltaic air conditioning system, a photovoltaic air conditioning system, and a photovoltaic air conditioner. This method dynamically adjusts the bus voltage to the optimal value by real-time monitoring of system operating parameters, including the MPPT voltage of the photovoltaic power supply and load status. This effectively avoids converter overcurrent protection problems caused by fixed bus voltage settings. The method can adjust the bus voltage to the optimal value in real time according to the input characteristics of the photovoltaic power supply and the system load requirements, ensuring stable operation of the system under different operating conditions. This approach not only improves the overall stability and reliability of the system but also optimizes its energy efficiency, making it suitable for photovoltaic air conditioning systems under various complex operating conditions.

[0006] The present invention adopts the following technical solution.

[0007] The first aspect of the present invention provides a method for dynamic adjustment of bus voltage in a photovoltaic air conditioning system, comprising:

[0008] The power demand of the air conditioner is calculated based on the compressor's operating frequency, and the system status of the photovoltaic air conditioner is determined by combining the photovoltaic power generation capacity.

[0009] When the photovoltaic air conditioner system is determined to be in inverter mode, the bus voltage is adjusted to the maximum power output point using the MPPT algorithm.

[0010] When the photovoltaic air conditioning system is determined to be in rectification mode, the bus voltage is optimized to the target value of the bus voltage through the PID control algorithm.

[0011] Preferably, the step of calculating the air conditioner's power demand based on the compressor's operating frequency and determining the system status of the photovoltaic air conditioner in conjunction with the photovoltaic power generation includes:

[0012] Calculate the photovoltaic power generation based on the output voltage and output current of the photovoltaic array;

[0013] Calculate the air conditioner's electricity demand based on the compressor's operating frequency;

[0014] If the photovoltaic power generation is greater than the air conditioning power demand, the system is determined to be in inverter mode; if the photovoltaic power generation is less than or equal to the air conditioning power demand, the system is determined to be in rectifier mode.

[0015] Preferably, when determining that the photovoltaic air conditioner's system state is in inverter mode, adjusting the bus voltage to the maximum power output point using the MPPT algorithm includes:

[0016] When the photovoltaic air conditioning system is determined to be in inverter mode, the initial photovoltaic input power of the photovoltaic array is obtained, and the initial disturbance direction and voltage disturbance step size are set.

[0017] The bus capacitor voltage after the disturbance is calculated by combining the initial disturbance direction and voltage disturbance step size with the bus capacitor voltage before the disturbance.

[0018] When the bus voltage is stable, sample the voltage and current of the photovoltaic array, calculate the current photovoltaic power generation, and solve for the power change based on the current photovoltaic power generation and the photovoltaic power generation before the disturbance.

[0019] The direction of subsequent disturbances is determined based on the power change.

[0020] The bus voltage is repeatedly disturbed according to the direction of subsequent disturbances until it equals the set MPPT voltage. The system is then determined to have reached the maximum power point, and regulation is terminated and the system enters steady state maintenance.

[0021] Preferably, when determining that the photovoltaic air conditioning system is in rectification mode, optimizing the bus voltage to the target value using a PID control algorithm includes:

[0022] When the photovoltaic air conditioning system is determined to be in rectification mode, a reinforcement learning algorithm is used to set the initial value of the bus voltage. When the air conditioner is turned on, the target value of the bus voltage is calculated based on the compressor operating frequency and the proportional coefficient.

[0023] The target value and initial value of the bus voltage are used to solve for the current bus voltage error. The error is then input into the PID control algorithm to solve for the proportional, integral, and derivative terms. Finally, the total control output is calculated based on the proportional, integral, and derivative terms.

[0024] The bus voltage of the bus capacitor is adjusted by the total control output. The PID control algorithm is repeatedly used to adjust the bus voltage until the bus voltage reaches the target value, thus obtaining the optimal bus voltage value.

[0025] Preferably, setting the initial value of the bus voltage using a reinforcement learning algorithm includes:

[0026] The compressor operating frequency and air conditioner start-up command are collected in real time through the inverter main control board, and a system state feature vector is constructed; a reinforcement learning agent policy network is constructed.

[0027] A reinforcement learning agent policy network is constructed based on the system state characteristics input, and learns the optimal voltage control policy at=[dynamic voltage coefficient, dynamic margin] under different system states;

[0028] Set the initial value of the bus voltage to AC line voltage × dynamic voltage coefficient + dynamic margin.

[0029] The second aspect of this invention provides a photovoltaic air conditioning system that operates the photovoltaic air conditioning system bus voltage dynamic adjustment method described in the first aspect, comprising: a converter main control board, an air conditioning main control board, a compressor, a bidirectional DC / AC converter, a bus capacitor, and a photovoltaic array;

[0030] The inverter main control board obtains the compressor's operating frequency from the air conditioner main control board to obtain the air conditioner's power demand, and determines the current system status by combining the photovoltaic power generation of the photovoltaic array;

[0031] If the main control board of the converter determines that the system state is inverter mode, it controls the bidirectional DC / AC converter to adjust the bus voltage of the bus capacitor through the MPPT algorithm so that the bus voltage operates at the maximum power output point.

[0032] If the main control board of the converter determines that the system state is rectification mode, it uses a reinforcement learning algorithm to set the initial value of the bus voltage and uses a PID algorithm to control the bidirectional DC / AC converter to stabilize the bus voltage of the bus capacitor to the target value of the bus voltage.

[0033] Preferably, if the photovoltaic power generation is greater than the air conditioning power demand calculated from the compressor operating frequency, it is determined to be in inverter mode;

[0034] If the photovoltaic power generation is less than or equal to the air conditioning power demand, it is determined to be in rectification mode.

[0035] Preferably, if the converter main control board determines that the system state is inverter mode, it obtains the initial photovoltaic input power of the photovoltaic array, controls the bidirectional DC / AC converter to generate voltage disturbance to change the bus voltage of the bus capacitor, obtains the photovoltaic power generation of the photovoltaic array when the bus voltage is stable, and controls the bidirectional DC / AC converter to adjust the bus voltage of the bus capacitor to the MPPT voltage in combination with the initial photovoltaic input power, and determines that the bus voltage is working at the maximum power output point.

[0036] Preferably, if the converter main control board determines that the system state is rectification mode, it obtains the air conditioner start command from the air conditioner main control board via RS485, and uses a reinforcement learning algorithm to solve for the optimal initial value of the bus voltage.

[0037] The converter main control board obtains the compressor's operating frequency from the air conditioner main control board via RS485 to solve for the target value of the bus voltage, and then uses a PID algorithm to control the bidirectional DC / AC converter to stabilize the bus voltage at the target value.

[0038] Preferably, the photovoltaic air conditioning system further includes an LC filter.

[0039] If the main control board of the converter determines that the system state is inverter mode, the photovoltaic array is connected to the bus capacitor to transmit DC power to the bus capacitor, maintaining energy buffering and voltage regulation; the LC filter converts the PWM wave output by the bidirectional DC / AC converter into a sinusoidal AC wave, and then outputs the electrical energy to the distribution network stably through the sinusoidal AC wave.

[0040] If the converter main control board determines that the system state is rectification mode, the distribution network will filter out harmonics by passing the LC filter, and then convert the AC power into DC power by passing the bidirectional DC / AC converter. The bidirectional DC / AC converter will then deliver the DC power to the bus capacitor for voltage stabilization and energy storage.

[0041] A photovoltaic air conditioner according to a third aspect of the present invention, the photovoltaic air conditioner comprising the photovoltaic air conditioning system as described in the second aspect.

[0042] Compared with the prior art, the beneficial effects of the present invention include at least the following:

[0043] This invention dynamically adjusts the bus voltage control strategy by monitoring real-time changes in energy supply and demand. In inverter mode, the bus voltage is fine-tuned through perturbation to ensure the photovoltaic array operates at maximum power. In rectification mode, the photovoltaic air conditioning system abandons MPPT tracking in inverter mode and instead adopts a load-centric bus voltage control strategy. Based on the real-time operating frequency of the compressor, feedforward control and PID closed-loop control stabilize the bus voltage at the target value. This solves the problem that when sunlight is insufficient, forcibly performing MPPT would cause the bus voltage to fluctuate with the light intensity, leading to poor inverter output power quality, unstable compressor operation, high noise, and even shutdown protection. This provides a stable DC power supply for the compressor of the photovoltaic air conditioning system, ensuring reliable operation of the photovoltaic air conditioning system under different loads and improving the stability, reliability, and service life of the photovoltaic air conditioning system. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the flow of the control method of the present invention provided according to an embodiment of the present invention;

[0045] Figure 2 This is a schematic diagram of the PID algorithm flow for bus voltage provided according to an embodiment of the present invention;

[0046] Figure 3 This is a schematic diagram of a photovoltaic air conditioning system provided according to an embodiment of the present invention. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0048] like Figure 1 As shown, Embodiment 1 of the present invention provides a method for dynamically adjusting the bus voltage of a photovoltaic air conditioner, which operates in a photovoltaic air conditioning system as described in Embodiment 1. This method solves the system operation problem caused by the fixed setting of the bus voltage in existing photovoltaic air conditioning systems, and includes a converter. The photovoltaic air conditioning system needs to dynamically adjust the bus voltage in both rectification and inversion operating modes, including the following steps:

[0049] Step 1: Calculate the air conditioner's power demand based on the compressor's operating frequency, and determine the system status of the photovoltaic air conditioner by combining the photovoltaic power generation output.

[0050] In a preferred but non-limiting embodiment of the present invention, step 1 includes:

[0051] Step 1.1: Calculate the photovoltaic power generation based on the output voltage and output current of the photovoltaic array, expressed by the following formula:

[0052]

[0053] In the formula,

[0054] Photovoltaic power generation capacity,

[0055] This is the output voltage of the photovoltaic array.

[0056] This provides the output current for the photovoltaic array.

[0057] Step 1.2: Calculate the air conditioner's power demand based on the compressor's operating frequency, expressed by the following formula:

[0058]

[0059] In the formula,

[0060] This indicates the power demand of the air conditioner, specifically the load power of the compressor.

[0061] This refers to the compressor's power-frequency characteristic coefficient.

[0062] This refers to the compressor's operating frequency.

[0063] Step 1.3: If the photovoltaic power generation is greater than the air conditioning power demand, the system is determined to be in inverter mode; if the photovoltaic power generation is less than or equal to the air conditioning power demand, the system is determined to be in rectifier mode.

[0064] It is worth noting that the photovoltaic air conditioning system can automatically determine the inverter and rectification modes based on the photovoltaic power generation and the air conditioning power demand, and intelligently switch the bus voltage strategy without manual intervention, thus improving the intelligent response of the photovoltaic air conditioning system.

[0065] Step 2: When the system state of the photovoltaic air conditioner is determined to be in inverter mode, the DC bus voltage of the photovoltaic air conditioner is adjusted to the maximum power output point through the MPPT algorithm.

[0066] In a preferred but non-limiting embodiment of the present invention, step 2 includes:

[0067] Step 2.1: When the photovoltaic air conditioning system in step 1 is in inverter mode, obtain the initial photovoltaic input power of the photovoltaic array and set the initial disturbance direction and voltage disturbance step size.

[0068] Step 2.2: The converter main control board controls the bidirectional DC / AC converter to generate a voltage disturbance. Based on the initial disturbance direction and voltage disturbance step size, the bus voltage of the bus capacitor changes. The bus voltage of the bus capacitor after the disturbance is obtained by combining the bus voltage before the disturbance with the bus voltage before the disturbance, expressed by the following formula:

[0069]

[0070] In the formula,

[0071] This represents the bus voltage of the bus capacitance before the disturbance.

[0072] This represents the bus voltage of the bus capacitor after the disturbance.

[0073] This represents the disturbance voltage.

[0074] Step 2.3: When the bus voltage is stable, sample the voltage and current of the photovoltaic array, calculate the current photovoltaic power generation, and solve for the power change based on the current photovoltaic power generation and the photovoltaic power generation before the disturbance.

[0075] Step 2.4: Determine the direction of subsequent disturbances based on the power change.

[0076] More preferably, step 2.4 includes:

[0077] If the power change is greater than 0, keep the current disturbance direction unchanged and repeat the previous operation;

[0078] If the power change is less than 0, reverse the voltage disturbance direction and operate again.

[0079] Step 2.5: Repeat the disturbances in steps 2.3-2.4 according to the direction of the subsequent disturbances until the bus voltage equals the set MPPT voltage. Determine that the system has reached the maximum power point, terminate the regulation and enter steady state maintenance.

[0080] More preferably, step 2.5 includes:

[0081] When the regulation is terminated and the steady-state maintenance phase is entered, the converter main control board stops voltage disturbances, keeps the current maximum power point unchanged, and continuously monitors changes in photovoltaic power. If the photovoltaic power changes, the steady-state maintenance phase is exited and the converter main control board restarts MPPT control to regulate the bus voltage.

[0082] By adjusting the output voltage of the photovoltaic modules or photovoltaic power source, the bus voltage is brought up to the set bus voltage, while maintaining the photovoltaic input power near the initial photovoltaic input power value. The specific voltage reduction needs to be quantified and adjusted based on the actual system conditions and design requirements.

[0083] Step 2.3: Detect the current photovoltaic input power when the bus voltage is stable as in Step 2.2.

[0084] It is worth noting that the MPPT control algorithm in this invention is only applied to the inverter mode, that is, when the photovoltaic power generation is greater than the power demand of the air conditioning system. At this time, the core objective of the photovoltaic air conditioning system is to maximize power generation. MPPT achieves maximum power point tracking by adjusting the DC bus voltage. The system controls the bidirectional DC / AC converter to send power to the grid, ensuring that every watt of excess photovoltaic power is sent to the grid to the maximum extent, thereby improving the global optimal efficiency in the inverter mode. In traditional systems, if MPPT is always enabled, the bus voltage will be forced to fluctuate continuously to track a point with very low power when the light is weak (rectification mode), which seriously endangers the stability of the system. This invention completely avoids the negative impact of MPPT in the rectification mode by switching modes, ensuring that the system can achieve efficient energy conversion under different light conditions, improving the stability of the system, and guaranteeing the global optimal efficiency in the inverter mode.

[0085] Step 3: When the photovoltaic air conditioning system in Step 1 is in rectification mode, set the bus voltage according to the air conditioning start command, and optimize the bus voltage to the optimal value through the PID control algorithm to ensure that the AC power output by the inverter is stably supplied to the air conditioning system.

[0086] In a preferred but non-limiting embodiment of the present invention, step 3 includes:

[0087] Step 3.1: When the photovoltaic air conditioning system in step 1 is in rectification mode, a reinforcement learning algorithm is used to solve for the initial value of the bus voltage.

[0088] More preferably, step 3.1 includes:

[0089] Step 3.1.1: The converter main control board collects and constructs the system status feature vector in real time, including the compressor operating frequency, photovoltaic power generation of the photovoltaic array, distribution network voltage, distribution network current, bus voltage of the previous sampling period, photovoltaic air conditioning system start-up time, and air conditioning start-up command.

[0090] Step 3.1.2: Construct a reinforcement learning agent policy network.

[0091] Step 3.1.3: Input the system state characteristics from Step 3.1.1 into the reinforcement learning agent policy network constructed in Step 3.1.2 to learn the optimal voltage control policy at=[dynamic voltage coefficient, dynamic margin] under different system states.

[0092] Step 3.1.4: Set the initial value of the bus voltage to AC line voltage × dynamic voltage coefficient + dynamic margin.

[0093] These thresholds are set based on factors such as system design requirements, load characteristics, and environmental conditions to ensure stable operation and efficiency optimization of the system under different conditions. The bus voltage range of this photovoltaic air conditioner is between 560-700V.

[0094] It is worth noting that in rectification mode, this invention uses a reinforcement learning agent to dynamically calculate the initial value of the bus voltage. The agent comprehensively considers multi-dimensional information such as compressor frequency, photovoltaic power, grid status, and historical data, and outputs an optimal dynamic voltage coefficient and dynamic margin, so that the system's starting control point is the optimal or near-optimal point. This solves the problems of slow response, reliance on experience to set fixed parameters, and inability to adapt to complex and changing operating conditions in traditional control methods. It makes the photovoltaic air conditioning system an intelligent system that can sense the environment, predict changes, and make optimal decisions, reducing overshoot, oscillation, and response time in the system adjustment process, achieving a fast and smooth transition, and improving the stability of the photovoltaic air conditioning system.

[0095] Step 3.2: When the air conditioner is turned on, the inverter main control board reads the compressor operating frequency f through RS485 communication and multiplies it with the proportional coefficient K0 to obtain the target value Uref of the bus voltage.

[0096] Step 3.3: The inverter main control board optimizes the bus voltage from step 3.1 to the target value of the bus voltage using a PID control algorithm to ensure that the AC power output by the inverter is stably supplied to the air conditioning system.

[0097] More preferably, step 3.3 includes:

[0098] Step 3.2.1, as follows Figure 2 As shown, the target value Uref of the bus voltage and the initial value of the bus voltage are input into the PID control algorithm to optimize the bus voltage to the target control voltage Uref.

[0099] More preferably, step 3.2.2 includes:

[0100] Calculate the current bus voltage error It can be expressed by the following formula:

[0101]

[0102] In the formula,

[0103] As a proportionality coefficient, the present invention uses a value of 0.8V / Hz, which means that for every 1Hz increase in compressor frequency, the target voltage increases by 0.8V;

[0104] The proportional term is calculated using the following formula:

[0105]

[0106] In the formula,

[0107] Output as a proportional term.

[0108] This is the proportional gain coefficient.

[0109] The integral term is calculated using the following formula:

[0110]

[0111] In the formula,

[0112] This indicates the output of the integral term for the current period.

[0113] This indicates the output of the proportional term from the previous cycle.

[0114] This is the integral gain coefficient.

[0115] The differential term is calculated using the following formula:

[0116]

[0117] In the formula,

[0118] Indicates the output of the differential term.

[0119] Represents the differential gain coefficient.

[0120] This indicates the voltage error of the previous bus.

[0121] The control quantity is calculated using the following formula:

[0122]

[0123] In the formula,

[0124] This indicates the total control output.

[0125] Limiting the range of control quantities to ensure they remain within a reasonable range includes:

[0126] like ,Pick ;

[0127] like ,Pick .

[0128] Total control output The output is sent to a bidirectional DC / AC converter to adjust its operating state, so that the bus voltage of the bus capacitor is stabilized at the target value Uref of the bus voltage.

[0129] Set the previous error to equal the current error, update the previous error, and wait for the next sampling period.

[0130] Besides dynamically adjusting the bus voltage to adapt to different operating conditions, this differentiated setting has another significant advantage: when the input voltage of the photovoltaic air conditioner is at the nominal minimum open-circuit voltage, if the control threshold of the bus voltage is set too high, the bus voltage may exceed the actual open-circuit voltage of the photovoltaic module. In this case, the diode connected between the photovoltaic module or photovoltaic power supply and the bus will be reverse-biased and unable to conduct properly. The system may detect an abnormal current signal, misinterpreting it as a low-light condition, thus triggering a low-light mode and affecting the normal operation and efficiency of the system. By dynamically adjusting the control threshold of the bus voltage, this misinterpretation can be avoided, ensuring stable and reliable operation of the system under different operating conditions.

[0131] It is worth noting that in rectification mode, this invention dynamically calculates the target value of the PID bus voltage based on the compressor operating frequency, so that the bus voltage is pre-matched with the power demand of the compressor. Traditional systems usually set a fixed high voltage target for the PID, such as 700V, and try to maintain 700V regardless of whether the compressor operating frequency is 10Hz or 60Hz. However, maintaining a fixed high voltage target at low frequencies will lead to unnecessary energy waste. The bus voltage strategy of this invention provides power supply on demand, which improves the stability and power supply efficiency of the air conditioning photovoltaic system in adjusting the bus voltage and reduces energy waste.

[0132] Step 4: Obtain the optimal bus voltage of the photovoltaic air conditioning system and realize dynamic adjustment of the photovoltaic air conditioning bus voltage.

[0133] like Figure 3 As shown, Embodiment 2 of the present invention provides a photovoltaic air conditioning system, including: a converter main control board, an air conditioning main control board, a compressor, a bidirectional DC / AC converter, a bus capacitor, and a photovoltaic array;

[0134] Includes: inverter main control board, air conditioning main control board, compressor, bidirectional DC / AC converter, bus capacitor and photovoltaic array;

[0135] The inverter main control board obtains the compressor's operating frequency from the air conditioner main control board via RS485 to obtain the air conditioner's power demand, and determines the current system status by combining the photovoltaic power generation of the photovoltaic array.

[0136] If the main control board of the converter determines that the system state is inverter mode, it controls the bidirectional DC / AC converter to adjust the bus voltage of the bus capacitor through the MPPT algorithm so that the bus voltage works at the maximum power output point.

[0137] If the main control board of the converter determines that the system is in rectification mode, it uses a PID algorithm to control the bidirectional DC / AC converter to stabilize the bus voltage at the target value of the bus voltage.

[0138] It is worth noting that this invention intelligently judges the system status through the inverter main control board and switches the working mode accordingly. It uses MPPT algorithm and reinforcement learning combined with PID intelligent algorithm for control, so that the system can maximize the photovoltaic power generation benefits and provide high-quality power supply for air conditioning. It achieves optimal energy efficiency from the system architecture level. The inverter main control board is clearly defined as the intelligent hub. Together with the air conditioning main control board, bidirectional DC / AC converter and other key hardware, it forms a physical entity that can execute the inventive method, thereby improving the intelligent response and energy efficiency of the photovoltaic air conditioning system.

[0139] Preferably, if the photovoltaic power generation is greater than the air conditioning power demand calculated from the compressor operating frequency, it is determined to be in inverter mode;

[0140] If the photovoltaic power generation is less than or equal to the air conditioning power demand, it is determined to be in rectification mode.

[0141] It is worth noting that this invention directly compares the relationship between photovoltaic power generation and air conditioning power demand, making the judgment logic clear and the response rapid. This effectively avoids frequent mode switching caused by slight fluctuations in sunlight or load, thus enhancing the stability and reliability of the system.

[0142] Preferably, if the converter main control board determines that the system state is inverter mode, it obtains the initial photovoltaic input power of the photovoltaic array, controls the bidirectional DC / AC converter to generate voltage disturbance to change the bus voltage of the bus capacitor, obtains the photovoltaic power generation of the photovoltaic array when the bus voltage is stable, and controls the bidirectional DC / AC converter to adjust the bus voltage of the bus capacitor to the MPPT voltage in combination with the initial photovoltaic input power, and determines that the bus voltage is working at the maximum power output point.

[0143] It is worth noting that this invention dynamically tracks the maximum power point using the MPPT algorithm, ensuring that the photovoltaic array always operates in its optimal state. This guarantees that every watt of photovoltaic potential is maximized when supplying power to the grid, improving the overall economic efficiency of the system and ensuring globally optimal efficiency in inverter mode. It also avoids the drastic fluctuations in bus voltage caused by forcibly tracking a very low power point in rectification mode during weak light conditions, thus ensuring stability in rectification mode from a theoretical perspective. Preferably, if the converter main control board determines that the system state is rectification mode, it obtains the air conditioner start-up command from the air conditioner main control board via RS485, and sets the initial value of the bus voltage according to the air conditioner start-up command using a reinforcement learning algorithm.

[0144] The converter main control board obtains the compressor's operating frequency from the air conditioner main control board via RS485 to solve for the target value of the bus voltage, and then uses a PID algorithm to control the bidirectional DC / AC converter to stabilize the bus voltage at the target value.

[0145] It is worth noting that this invention uses a reinforcement learning algorithm to set the initial bus voltage, so that the system's starting control point is the optimal or near-optimal point. This solves the problems of slow response and reliance on experience to set fixed parameters in traditional PID controllers, achieving a fast and smooth transition, reducing overshoot and oscillation. The introduction of reinforcement learning enables the system to comprehensively consider multi-dimensional information such as compressor frequency, photovoltaic power, and grid status, and output the optimal decision. This makes the photovoltaic air conditioning system an intelligent system that adapts to complex and variable operating conditions, improving the intelligence of the photovoltaic air conditioning system.

[0146] Preferably, the photovoltaic air conditioning system further includes an LC filter.

[0147] If the main control board of the converter determines that the system state is inverter mode, the photovoltaic array is connected to the bus capacitor to transmit DC power to the bus capacitor, maintaining energy buffering and voltage regulation; the LC filter converts the PWM wave output by the bidirectional DC / AC converter into a sinusoidal AC wave, and then outputs the electrical energy to the distribution network stably through the sinusoidal AC wave.

[0148] If the main control board of the converter determines that the system is in rectification mode, the power distribution network will filter out harmonics through the LC filter, and then convert the AC power into DC power through the bidirectional DC / AC converter. The bidirectional DC / AC converter will then deliver the DC power to the bus capacitor for voltage stabilization and energy storage.

[0149] It is worth noting that this invention completes the construction of the physical path for bidirectional energy flow, clarifies the role of LC filters and distribution networks in both modes and the direction of energy flow, and ensures power quality and system safety.

[0150] Embodiment 3 of the present invention provides a photovoltaic air conditioning system operating as described in Embodiment 2. Embodiment 4 of the present invention provides a method for dynamically adjusting the bus voltage of a photovoltaic air conditioning system operating as described in Embodiment 1, comprising the following steps:

[0151] Step 1: Calculate the air conditioner's power demand based on the compressor's operating frequency, and determine the system status of the photovoltaic air conditioner by combining the photovoltaic power generation output.

[0152] In a preferred but non-limiting embodiment of the present invention, step 1 includes:

[0153] Step 1.1: Calculate the photovoltaic power generation based on the output voltage and output current of the photovoltaic array.

[0154] Step 1.2: Calculate the air conditioner's power demand based on the compressor's operating frequency.

[0155] Step 1.3: If the photovoltaic power generation is greater than the air conditioning power demand, the system is determined to be in inverter mode; if the photovoltaic power generation is less than or equal to the air conditioning power demand, the system is determined to be in rectifier mode.

[0156] Step 2: When the system state of the photovoltaic air conditioner is determined to be in inverter mode, the DC bus voltage of the photovoltaic air conditioner is adjusted to the maximum power output point through the MPPT algorithm.

[0157] In a preferred but non-limiting embodiment of the present invention, step 2 includes:

[0158] Step 2.1: When the photovoltaic air conditioning system in step 1 is in inverter mode, obtain the initial photovoltaic input power of the photovoltaic array and set the initial disturbance direction and voltage disturbance step size.

[0159] Step 2.2: The main control board of the converter controls the bidirectional DC / AC converter to generate voltage disturbance. According to the initial disturbance direction and voltage disturbance step size, the bus voltage of the bus capacitor changes. The bus voltage of the bus capacitor after the disturbance is obtained by combining the bus voltage of the bus capacitor before the disturbance.

[0160] Step 2.3: When the bus voltage is stable, sample the voltage and current of the photovoltaic array, calculate the current photovoltaic power generation, and solve for the power change based on the current photovoltaic power generation and the photovoltaic power generation before the disturbance.

[0161] Step 2.4: Determine the direction of subsequent disturbances based on the power change.

[0162] More preferably, step 2.4 includes:

[0163] If the power change is greater than 0, keep the current disturbance direction unchanged and repeat the previous operation;

[0164] If the power change is less than 0, reverse the voltage disturbance direction and operate again.

[0165] Step 2.5: Repeat the disturbances in steps 2.3-2.4 according to the direction of the subsequent disturbances until the bus voltage equals the set MPPT voltage. Determine that the system has reached the maximum power point, terminate the regulation and enter steady state maintenance.

[0166] More preferably, step 2.5 includes:

[0167] When the regulation is terminated and the steady-state maintenance phase is entered, the converter main control board stops voltage disturbances, keeps the current maximum power point unchanged, and continuously monitors changes in photovoltaic power. If the photovoltaic power changes, the steady-state maintenance phase is exited and the converter main control board restarts MPPT control to regulate the bus voltage.

[0168] By adjusting the output voltage of the photovoltaic modules or photovoltaic power source, the bus voltage is brought up to the set bus voltage, while maintaining the photovoltaic input power near the initial photovoltaic input power value. The specific voltage reduction needs to be quantified and adjusted based on the actual system conditions and design requirements.

[0169] In photovoltaic (PV) air conditioning systems, the DC bus voltage control strategy is one of the key technologies to ensure efficient and stable system operation. In inverter mode, the DC bus voltage of the PV air conditioner is regulated by the MPPT (Maximum Power Point Tracking) output voltage of the PV modules or PV power source, and its voltage level dynamically adjusts with changes in the MPPT output voltage. Specifically, the system tracks the maximum power point of the PV power source in real time using the MPPT algorithm, maintaining the bus voltage within the optimal operating range, thereby ensuring efficient energy conversion under different lighting conditions.

[0170] Step 3: When the photovoltaic air conditioning system in Step 1 is in rectification mode, set the bus voltage according to the air conditioning start command, and optimize the bus voltage to the optimal value through the PID control algorithm to ensure that the AC power output by the inverter is stably supplied to the air conditioning system.

[0171] In a preferred but non-limiting embodiment of the present invention, step 3 includes:

[0172] Step 3.1: When the photovoltaic air conditioning system in step 1 is in rectification mode, a reinforcement learning algorithm is used to solve for the initial value of the bus voltage.

[0173] More preferably, step 3.1 includes:

[0174] Step 3.1.1: The converter main control board collects and constructs the system status feature vector in real time, including the compressor operating frequency, photovoltaic power generation of the photovoltaic array, distribution network voltage, distribution network current, bus voltage of the previous sampling period, photovoltaic air conditioning system start-up time, and air conditioning start-up command.

[0175] Step 3.1.2: The air conditioner's power-on command is "power off," and a reinforcement learning agent policy network is constructed.

[0176] Step 3.1.3: Input the system state characteristics from Step 3.1.1 into the reinforcement learning agent policy network constructed in Step 3.1.2 to learn the optimal voltage control policy at=[1.414, 20V] under different system states.

[0177] Step 3.1.4: Set the initial value of the bus voltage to AC line voltage × 1.414 + 20V;

[0178] These thresholds are set based on factors such as system design requirements, load characteristics, and environmental conditions to ensure stable operation and efficiency optimization of the system under different conditions. The bus voltage range of this photovoltaic air conditioner is between 560-700V.

[0179] Step 3.2: When the air conditioner is turned on, the inverter main control board reads the compressor operating frequency f through RS485 communication and multiplies it with the proportional coefficient K0 to obtain the target value Uref of the bus voltage.

[0180] Step 3.3: The inverter main control board optimizes the bus voltage from step 3.1 to the target value of the bus voltage using a PID control algorithm to ensure that the AC power output by the inverter is stably supplied to the air conditioning system.

[0181] More preferably, step 3.3 includes:

[0182] Step 3.2.1: Input the target value Uref of the bus voltage and the initial value of the bus voltage into the PID control algorithm to optimize the bus voltage to the target control voltage Uref.

[0183] More preferably, step 3.2.2 includes:

[0184] Calculate the current bus voltage error ;

[0185] Calculate the proportional term, integral term, derivative term, and control quantity.

[0186] Limit the range of control quantities to ensure that the control quantities are within a reasonable range.

[0187] Total control output The output is sent to a bidirectional DC / AC converter to adjust its operating state, so that the bus voltage of the bus capacitor is stabilized at the target value Uref of the bus voltage.

[0188] Set the previous error to equal the current error, update the previous error, and wait for the next sampling period.

[0189] Besides dynamically adjusting the bus voltage to adapt to different operating conditions, this differentiated setting has another significant advantage: when the input voltage of the photovoltaic air conditioner is at the nominal minimum open-circuit voltage, if the control threshold of the bus voltage is set too high, the bus voltage may exceed the actual open-circuit voltage of the photovoltaic module. In this case, the diode connected between the photovoltaic module or photovoltaic power supply and the bus will be reverse-biased and unable to conduct properly. The system may detect an abnormal current signal, misinterpreting it as a low-light condition, thus triggering a low-light mode and affecting the normal operation and efficiency of the system. By dynamically adjusting the control threshold of the bus voltage, this misinterpretation can be avoided, ensuring stable and reliable operation of the system under different operating conditions.

[0190] Step 4: Obtain the optimal bus voltage of the photovoltaic air conditioning system and realize dynamic adjustment of the photovoltaic air conditioning bus voltage.

[0191] Embodiment 5 of the present invention operates on the method for dynamically adjusting the bus voltage of a photovoltaic air conditioner as described in Embodiment 1, and includes the following steps:

[0192] Step 1: Calculate the air conditioner's power demand based on the compressor's operating frequency, and determine the system status of the photovoltaic air conditioner by combining the photovoltaic power generation output.

[0193] In a preferred but non-limiting embodiment of the present invention, step 1 includes:

[0194] Step 1.1: Calculate the photovoltaic power generation based on the output voltage and output current of the photovoltaic array.

[0195] Step 1.2: Calculate the air conditioner's power demand based on the compressor's operating frequency.

[0196] Step 1.3: If the photovoltaic power generation is greater than the air conditioning power demand, the system is determined to be in inverter mode; if the photovoltaic power generation is less than or equal to the air conditioning power demand, the system is determined to be in rectifier mode.

[0197] Step 2: When the system state of the photovoltaic air conditioner is determined to be in inverter mode, the DC bus voltage of the photovoltaic air conditioner is adjusted to the maximum power output point through the MPPT algorithm.

[0198] In a preferred but non-limiting embodiment of the present invention, step 2 includes:

[0199] Step 2.1: When the photovoltaic air conditioning system in step 1 is in inverter mode, obtain the initial photovoltaic input power of the photovoltaic array and set the initial disturbance direction and voltage disturbance step size.

[0200] Step 2.2: The main control board of the converter controls the bidirectional DC / AC converter to generate voltage disturbance. According to the initial disturbance direction and voltage disturbance step size, the bus voltage of the bus capacitor changes. The bus voltage of the bus capacitor after the disturbance is obtained by combining the bus voltage of the bus capacitor before the disturbance.

[0201] Step 2.3: When the bus voltage is stable, sample the voltage and current of the photovoltaic array, calculate the current photovoltaic power generation, and solve for the power change based on the current photovoltaic power generation and the photovoltaic power generation before the disturbance.

[0202] Step 2.4: Determine the direction of subsequent disturbances based on the power change.

[0203] More preferably, step 2.4 includes:

[0204] If the power change is greater than 0, keep the current disturbance direction unchanged and repeat the previous operation;

[0205] If the power change is less than 0, reverse the voltage disturbance direction and operate again.

[0206] Step 2.5: Repeat the disturbances in steps 2.3-2.4 according to the direction of the subsequent disturbances until the bus voltage equals the set MPPT voltage. Determine that the system has reached the maximum power point, terminate the regulation and enter steady state maintenance.

[0207] More preferably, step 2.5 includes:

[0208] When the regulation is terminated and the steady-state maintenance phase is entered, the converter main control board stops voltage disturbances, keeps the current maximum power point unchanged, and continuously monitors changes in photovoltaic power. If the photovoltaic power changes, the steady-state maintenance phase is exited and the converter main control board restarts MPPT control to regulate the bus voltage.

[0209] By adjusting the output voltage of the photovoltaic modules or photovoltaic power source, the bus voltage is brought up to the set bus voltage, while maintaining the photovoltaic input power near the initial photovoltaic input power value. The specific voltage reduction needs to be quantified and adjusted based on the actual system conditions and design requirements.

[0210] In photovoltaic (PV) air conditioning systems, the DC bus voltage control strategy is one of the key technologies to ensure efficient and stable system operation. In inverter mode, the DC bus voltage of the PV air conditioner is regulated by the MPPT (Maximum Power Point Tracking) output voltage of the PV modules or PV power source, and its voltage level dynamically adjusts with changes in the MPPT output voltage. Specifically, the system tracks the maximum power point of the PV power source in real time using the MPPT algorithm, maintaining the bus voltage within the optimal operating range, thereby ensuring efficient energy conversion under different lighting conditions.

[0211] Step 3: When the photovoltaic air conditioning system in Step 1 is in rectification mode, set the bus voltage according to the air conditioning start command, and optimize the bus voltage to the optimal value through the PID control algorithm to ensure that the AC power output by the inverter is stably supplied to the air conditioning system.

[0212] In a preferred but non-limiting embodiment of the present invention, step 3 includes:

[0213] Step 3.1: When the photovoltaic air conditioning system in step 1 is in rectification mode, a reinforcement learning algorithm is used to solve for the initial value of the bus voltage.

[0214] More preferably, step 3.1 includes:

[0215] Step 3.1.1: The converter main control board collects and constructs the system status feature vector in real time, including the compressor operating frequency, photovoltaic power generation of the photovoltaic array, distribution network voltage, distribution network current, bus voltage of the previous sampling period, photovoltaic air conditioning system start-up time, and air conditioning start-up command.

[0216] Step 3.1.2: The air conditioner is turned on as the command to start the air conditioner. A reinforcement learning agent policy network is then constructed.

[0217] Step 3.1.3: Input the system state characteristics from Step 3.1.1 into the reinforcement learning agent policy network constructed in Step 3.1.2 to learn the optimal voltage control policy at=[1.414, 110V] under different system states.

[0218] Step 3.1.4: Set the initial value of the bus voltage to AC line voltage × 1.414 + 110V;

[0219] These thresholds are set based on factors such as system design requirements, load characteristics, and environmental conditions to ensure stable operation and efficiency optimization of the system under different conditions. The bus voltage range of this photovoltaic air conditioner is between 560-700V.

[0220] In rectifier operation mode, the DC bus voltage of the photovoltaic air conditioner dynamically adjusts its voltage control threshold based on whether the system receives a control command to turn on the air conditioner. When the system does not receive a command to turn on the air conditioner, the bus voltage is controlled at a lower threshold to optimize system efficiency and reduce energy consumption.

[0221] Step 3.2: When the air conditioner is turned on, the inverter main control board reads the compressor operating frequency f through RS485 communication and multiplies it with the proportional coefficient K0 to obtain the target value Uref of the bus voltage.

[0222] Step 3.3: The inverter main control board optimizes the bus voltage from step 3.1 to the target value of the bus voltage using a PID control algorithm to ensure that the AC power output by the inverter is stably supplied to the air conditioning system.

[0223] More preferably, step 3.3 includes:

[0224] Step 3.2.1: Input the target value Uref of the bus voltage and the initial value of the bus voltage into the PID control algorithm to optimize the bus voltage to the target control voltage Uref.

[0225] More preferably, step 3.2.2 includes:

[0226] Calculate the current bus voltage error ;

[0227] Calculate the proportional term, integral term, derivative term, and control quantity.

[0228] Limit the range of control quantities to ensure that the control quantities are within a reasonable range.

[0229] Total control output The output is sent to a bidirectional DC / AC converter to adjust its operating state, so that the bus voltage of the bus capacitor is stabilized at the target value Uref of the bus voltage.

[0230] Set the previous error to equal the current error, update the previous error, and wait for the next sampling period.

[0231] Besides dynamically adjusting the bus voltage to adapt to different operating conditions, this differentiated setting has another significant advantage: when the input voltage of the photovoltaic air conditioner is at the nominal minimum open-circuit voltage, if the control threshold of the bus voltage is set too high, the bus voltage may exceed the actual open-circuit voltage of the photovoltaic module. In this case, the diode connected between the photovoltaic module or photovoltaic power supply and the bus will be reverse-biased and unable to conduct properly. The system may detect an abnormal current signal, misinterpreting it as a low-light condition, thus triggering a low-light mode and affecting the normal operation and efficiency of the system. By dynamically adjusting the control threshold of the bus voltage, this misinterpretation can be avoided, ensuring stable and reliable operation of the system under different operating conditions.

[0232] Step 4: Obtain the optimal bus voltage of the photovoltaic air conditioning system and realize dynamic adjustment of the photovoltaic air conditioning bus voltage.

[0233] Embodiment 5 of the present invention operates on the method for dynamically adjusting the bus voltage of a photovoltaic air conditioner as described in Embodiment 1, and includes the following steps:

[0234] Step 1: Calculate the air conditioner's power demand based on the compressor's operating frequency, and determine the system status of the photovoltaic air conditioner by combining the photovoltaic power generation output.

[0235] In a preferred but non-limiting embodiment of the present invention, step 1 includes:

[0236] Step 1.1: Calculate the photovoltaic power generation based on the output voltage and output current of the photovoltaic array.

[0237] Step 1.2: Calculate the air conditioner's power demand based on the compressor's operating frequency.

[0238] Step 1.3: If the photovoltaic power generation is greater than the air conditioning power demand, the system is determined to be in inverter mode; if the photovoltaic power generation is less than or equal to the air conditioning power demand, the system is determined to be in rectifier mode.

[0239] Step 2: When the system state of the photovoltaic air conditioner is determined to be in inverter mode, the DC bus voltage of the photovoltaic air conditioner is adjusted to the maximum power output point through the MPPT algorithm.

[0240] In a preferred but non-limiting embodiment of the present invention, step 2 includes:

[0241] Step 2.1: When the photovoltaic air conditioning system in step 1 is in inverter mode, obtain the initial photovoltaic input power of the photovoltaic array and set the initial disturbance direction and voltage disturbance step size.

[0242] Step 2.2: The main control board of the converter controls the bidirectional DC / AC converter to generate voltage disturbance. According to the initial disturbance direction and voltage disturbance step size, the bus voltage of the bus capacitor changes. The bus voltage of the bus capacitor after the disturbance is obtained by combining the bus voltage of the bus capacitor before the disturbance.

[0243] Step 2.3: When the bus voltage is stable, sample the voltage and current of the photovoltaic array, calculate the current photovoltaic power generation, and solve for the power change based on the current photovoltaic power generation and the photovoltaic power generation before the disturbance.

[0244] Step 2.4: Determine the direction of subsequent disturbances based on the power change.

[0245] More preferably, step 2.4 includes:

[0246] If the power change is greater than 0, keep the current disturbance direction unchanged and repeat the previous operation;

[0247] If the power change is less than 0, reverse the voltage disturbance direction and operate again.

[0248] Step 2.5: Repeat the disturbances in steps 2.3-2.4 according to the direction of the subsequent disturbances until the bus voltage equals the set MPPT voltage. Determine that the system has reached the maximum power point, terminate the regulation and enter steady state maintenance.

[0249] More preferably, step 2.5 includes:

[0250] When the regulation is terminated and the steady-state maintenance phase is entered, the converter main control board stops voltage disturbances, keeps the current maximum power point unchanged, and continuously monitors changes in photovoltaic power. If the photovoltaic power changes, the steady-state maintenance phase is exited and the converter main control board restarts MPPT control to regulate the bus voltage.

[0251] The bus voltage is set to 110V, and the initial photovoltaic input power is x1.414+20V. The output voltage of the photovoltaic modules or photovoltaic power supply is adjusted to bring the bus voltage up to 110V while maintaining the photovoltaic input power around x1.414+20V. The specific voltage reduction needs to be quantified and adjusted based on the actual system conditions and design requirements.

[0252] Step 2.3: Detect the current photovoltaic input power when the bus voltage is stable as in Step 2.2.

[0253] In photovoltaic (PV) air conditioning systems, the DC bus voltage control strategy is one of the key technologies to ensure efficient and stable system operation. In inverter mode, the DC bus voltage of the PV air conditioner is regulated by the MPPT (Maximum Power Point Tracking) output voltage of the PV modules or PV power source, and its voltage level dynamically adjusts with changes in the MPPT output voltage. Specifically, the system tracks the maximum power point of the PV power source in real time using the MPPT algorithm, maintaining the bus voltage within the optimal operating range, thereby ensuring efficient energy conversion under different lighting conditions.

[0254] Step 3: When the photovoltaic air conditioning system in Step 1 is in rectification mode, set the bus voltage according to the air conditioning start command, and optimize the bus voltage to the optimal value through the PID control algorithm to ensure that the AC power output by the inverter is stably supplied to the air conditioning system.

[0255] In a preferred but non-limiting embodiment of the present invention, step 3 includes:

[0256] Step 3.1: When the photovoltaic air conditioning system in step 1 is in rectification mode, a reinforcement learning algorithm is used to solve for the initial value of the bus voltage.

[0257] More preferably, step 3.1 includes:

[0258] Step 3.1.1: The converter main control board collects and constructs the system status feature vector in real time, including the compressor operating frequency, photovoltaic power generation of the photovoltaic array, distribution network voltage, distribution network current, bus voltage of the previous sampling period, photovoltaic air conditioning system start-up time, and air conditioning start-up command.

[0259] Step 3.1.2: The air conditioner is turned on as the command to start the air conditioner. A reinforcement learning agent policy network is then constructed.

[0260] Step 3.1.3: Input the system state characteristics from Step 3.1.1 into the reinforcement learning agent policy network constructed in Step 3.1.2 to learn the optimal voltage control policy at=[1.414, 110V] under different system states.

[0261] Step 3.1.4: Set the initial value of the bus voltage to AC line voltage × 1.414 + 110V;

[0262] These thresholds are set based on factors such as system design requirements, load characteristics, and environmental conditions to ensure stable operation and efficiency optimization of the system under different conditions. The bus voltage range of this photovoltaic air conditioner is between 560-700V.

[0263] In rectifier operation mode, the DC bus voltage of the photovoltaic air conditioner dynamically adjusts its voltage control threshold based on whether the system receives a control command to turn on the air conditioner. When the system does not receive a command to turn on the air conditioner, the bus voltage is controlled at a lower threshold to optimize system efficiency and reduce energy consumption.

[0264] Step 3.2: When the air conditioner is turned on, the inverter main control board reads the compressor operating frequency f through RS485 communication and multiplies it with the proportional coefficient K0 to obtain the target value Uref of the bus voltage.

[0265] Step 3.3: The inverter main control board optimizes the bus voltage from step 3.1 to the target value of the bus voltage using a PID control algorithm to ensure that the AC power output by the inverter is stably supplied to the air conditioning system.

[0266] More preferably, step 3.3 includes:

[0267] Step 3.2.1: Input the target value and initial value of the bus voltage into the PID control algorithm to optimize the bus voltage to the target control voltage.

[0268] More preferably, step 3.2.2 includes:

[0269] Calculate the current bus voltage error ;

[0270] Calculate the proportional term, integral term, derivative term, and control quantity.

[0271] Limit the range of control quantities to ensure that the control quantities are within a reasonable range.

[0272] Total control output The output is sent to a bidirectional DC / AC converter to adjust its operating state, so that the bus voltage of the bus capacitor is stabilized at the target value of the bus voltage.

[0273] Set the previous error to equal the current error, update the previous error, and wait for the next sampling period.

[0274] Besides dynamically adjusting the bus voltage to adapt to different operating conditions, this differentiated setting has another significant advantage: when the input voltage of the photovoltaic air conditioner is at the nominal minimum open-circuit voltage, if the control threshold of the bus voltage is set too high, the bus voltage may exceed the actual open-circuit voltage of the photovoltaic module. In this case, the diode connected between the photovoltaic module or photovoltaic power supply and the bus will be reverse-biased and unable to conduct properly. The system may detect an abnormal current signal, misinterpreting it as a low-light condition, thus triggering a low-light mode and affecting the normal operation and efficiency of the system. By dynamically adjusting the control threshold of the bus voltage, this misinterpretation can be avoided, ensuring stable and reliable operation of the system under different operating conditions.

[0275] Step 4: Obtain the optimal bus voltage of the photovoltaic air conditioning system and realize dynamic adjustment of the photovoltaic air conditioning bus voltage.

[0276] Compared with the prior art, the beneficial effects of the present invention include at least the following:

[0277] This invention dynamically adjusts the bus voltage control strategy by monitoring real-time changes in energy supply and demand. In inverter mode, the bus voltage is fine-tuned through perturbation to ensure the photovoltaic array operates at maximum power. In rectification mode, the photovoltaic air conditioning system abandons MPPT tracking in inverter mode and instead adopts a load-centric bus voltage control strategy. Based on the real-time operating frequency of the compressor, feedforward control and PID closed-loop control stabilize the bus voltage at the target value. This solves the problem that when sunlight is insufficient, forcibly performing MPPT would cause the bus voltage to fluctuate with the light intensity, leading to poor inverter output power quality, unstable compressor operation, high noise, and even shutdown protection. This provides a stable DC power supply for the compressor of the photovoltaic air conditioning system, ensuring reliable operation of the photovoltaic air conditioning system under different loads and improving the stability, reliability, and service life of the photovoltaic air conditioning system.

[0278] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0279] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for dynamic adjustment of bus voltage in a photovoltaic air conditioning system, characterized in that: The power demand of the air conditioner is calculated based on the compressor operating frequency and the compressor power-frequency characteristic coefficient. The system status of the photovoltaic air conditioner is determined by combining the photovoltaic power generation. If the photovoltaic power generation is greater than the power demand of the air conditioner, the system status is determined to be inverter mode. If the photovoltaic power generation is less than or equal to the power demand of the air conditioner, the system status is determined to be rectifier mode. When the photovoltaic air conditioner system is determined to be in inverter mode, the bus voltage is adjusted to the maximum power output point using the MPPT algorithm. When the photovoltaic air conditioning system is determined to be in rectification mode, the PID control algorithm optimizes the bus voltage to the target value, including: When the photovoltaic air conditioning system is determined to be in rectification mode, a reinforcement learning algorithm is used to set the initial value of the bus voltage. When the air conditioner is turned on, the target value of the bus voltage is calculated based on the compressor operating frequency and the proportional coefficient. The target value and initial value of the bus voltage are used to solve for the current bus voltage error. The error is then input into the PID control algorithm to solve for the proportional, integral, and derivative terms. Finally, the total control output is calculated based on the proportional, integral, and derivative terms. The bus voltage of the bus capacitor is adjusted by the total control output. The PID control algorithm is repeatedly used to adjust the bus voltage until the bus voltage reaches the target value, thus obtaining the optimal bus voltage value. The step of setting the initial value of the bus voltage using a reinforcement learning algorithm includes: The compressor operating frequency and air conditioner start-up command are collected in real time through the inverter main control board, and a system state feature vector is constructed; a reinforcement learning agent policy network is constructed. A reinforcement learning agent policy network is constructed based on the system state characteristics input, and learns the optimal voltage control policy at=[dynamic voltage coefficient, dynamic margin] under different system states; The initial value of the bus voltage is set as AC line voltage × dynamic voltage coefficient + dynamic margin.

2. The method for dynamic adjustment of bus voltage in a photovoltaic air conditioning system according to claim 1, characterized in that: The process of calculating the air conditioner's power demand based on the compressor's operating frequency and determining the system status of the photovoltaic air conditioner by combining this with the photovoltaic power generation includes: Calculate the photovoltaic power generation based on the output voltage and output current of the photovoltaic array; Calculate the air conditioner's electricity demand based on the compressor's operating frequency; If the photovoltaic power generation is greater than the air conditioning power demand, the system is determined to be in inverter mode; if the photovoltaic power generation is less than or equal to the air conditioning power demand, the system is determined to be in rectifier mode.

3. The method for dynamic adjustment of bus voltage in a photovoltaic air conditioning system according to claim 1, characterized in that: When determining that the photovoltaic air conditioner's system state is in inverter mode, adjusting the bus voltage to the maximum power output point using the MPPT algorithm includes: When the photovoltaic air conditioning system is determined to be in inverter mode, the initial photovoltaic input power of the photovoltaic array is obtained, and the initial disturbance direction and voltage disturbance step size are set. The bus capacitor voltage after the disturbance is calculated by combining the initial disturbance direction and voltage disturbance step size with the bus capacitor voltage before the disturbance. When the bus voltage is stable, sample the voltage and current of the photovoltaic array, calculate the current photovoltaic power generation, and solve for the power change based on the current photovoltaic power generation and the photovoltaic power generation before the disturbance. The direction of subsequent disturbances is determined based on the power change. The bus voltage is repeatedly disturbed according to the direction of subsequent disturbances until it equals the set MPPT voltage. The system is then determined to have reached the maximum power point, and regulation is terminated and the system enters steady state maintenance.

4. A photovoltaic air conditioning system, operating the photovoltaic air conditioning system bus voltage dynamic adjustment method according to any one of claims 1-3, characterized in that: include: Inverter main control board, air conditioner main control board, compressor, bidirectional DC / AC converter, bus capacitor and photovoltaic array; The inverter main control board obtains the operating frequency of the compressor from the air conditioner main control board to obtain the air conditioner's power demand, and determines the current system status by combining the photovoltaic power generation of the photovoltaic array; If the main control board of the converter determines that the system state is inverter mode, it controls the bidirectional DC / AC converter to adjust the bus voltage of the bus capacitor through the MPPT algorithm so that the bus voltage operates at the maximum power output point. If the main control board of the converter determines that the system state is rectification mode, it uses a reinforcement learning algorithm to set the initial value of the bus voltage and uses a PID algorithm to control the bidirectional DC / AC converter to stabilize the bus voltage of the bus capacitor to the target value of the bus voltage.

5. A photovoltaic air conditioning system according to claim 4, characterized in that: If the photovoltaic power generation is greater than the air conditioning power demand calculated from the compressor operating frequency, it is determined to be in inverter mode; If the photovoltaic power generation is less than or equal to the air conditioning power demand, it is determined to be in rectification mode.

6. A photovoltaic air conditioning system according to claim 4 or 5, characterized in that: If the main control board of the converter determines that the system state is inverter mode, it obtains the initial photovoltaic input power of the photovoltaic array, controls the bidirectional DC / AC converter to generate voltage disturbance to change the bus voltage of the bus capacitor, obtains the photovoltaic power generation of the photovoltaic array when the bus voltage is stable, and controls the bidirectional DC / AC converter to adjust the bus voltage of the bus capacitor to the MPPT voltage in combination with the initial photovoltaic input power, and determines that the bus voltage is working at the maximum power output point.

7. A photovoltaic air conditioning system according to claim 4 or 5, characterized in that: If the converter main control board determines that the system state is rectification mode, it obtains the air conditioner start command from the air conditioner main control board via RS485, and uses a reinforcement learning algorithm to solve for the optimal initial value of the bus voltage. The converter main control board obtains the compressor's operating frequency from the air conditioner main control board via RS485 to solve for the target value of the bus voltage, and then uses a PID algorithm to control the bidirectional DC / AC converter to stabilize the bus voltage at the target value.

8. A photovoltaic air conditioning system according to claim 4 or 5, characterized in that: The photovoltaic air conditioning system also includes an LC filter. If the main control board of the converter determines that the system state is inverter mode, the photovoltaic array is connected to the bus capacitor to transmit DC power to the bus capacitor, maintaining energy buffering and voltage regulation; the LC filter converts the PWM wave output by the bidirectional DC / AC converter into a sinusoidal AC wave, and then outputs the electrical energy to the distribution network stably through the sinusoidal AC wave. If the converter main control board determines that the system state is rectification mode, the distribution network will filter out harmonics by passing the LC filter, and then convert the AC power into DC power by passing the bidirectional DC / AC converter. The bidirectional DC / AC converter will then deliver the DC power to the bus capacitor for voltage stabilization and energy storage.

9. A photovoltaic air conditioner, characterized in that, The photovoltaic air conditioner includes the photovoltaic air conditioning system as described in any one of claims 5 to 8.

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