A frequency converter control method, computer readable storage medium and air conditioner for photovoltaic MPPT panel

Abstract

The application provides a frequency converter control method for a photovoltaic MPPT panel, a computer readable storage medium and an air conditioner. The program starts, voltage sampling is performed through a sampling circuit, Ave_Vdc and Err_Vdc are obtained, is input into a fuzzy PID controller, a fuzzy PID control is designed as an input quantity of the fuzzy controller, a simulation model is built, and the reliability of the algorithm is verified; then the algorithm is written into a program, whether the frequency converter speed Wr is greater than the minimum frequency converter speed Wr_Min is judged, when the frequency converter speed Wr is less than the minimum frequency converter speed Wr_Min, the frequency converter stops at the minimum speed, and a large impact current is not brought to the frequency converter hardware; in combination with the actual test situation, the fuzzy control is adopted, the output speed of the frequency converter is dynamically adjusted according to the bus voltage, and under the change of complex light conditions, the frequency converter can change the power consumption according to the power supplied by the MPPT photovoltaic panel, so that the effect of abnormal fault shutdown is achieved.

Description

Technical Field

[0001] This invention relates to photovoltaic air conditioning frequency conversion control technology, and more particularly to a frequency converter control method for photovoltaic MPPT boards, a computer-readable storage medium, and an air conditioner. Background Technology

[0002] The MPPT controller can detect the voltage generated by the solar panels in real time and track the peak voltage and current (VI) value, enabling the system to charge the battery at maximum power output. Applied to solar photovoltaic systems, it coordinates the operation of solar panels, batteries, and loads, acting as the brain of the photovoltaic system. The main function of MPPT technology is to improve the output efficiency of power generation equipment, ensuring maximum power output under various environmental conditions. In photovoltaic solar systems, MPPT technology is implemented through the inverter, ensuring that solar panels output maximum power under various weather conditions, meeting household electricity needs and reducing electricity bills.

[0003] However, when the inverter is powered by MPPT photovoltaic panels, the following situations may occur when the photovoltaic and mains power are mixed: (1) The photovoltaic and mains power work simultaneously and provide stable power; (2) As the light conditions change, the power supplied by the MPPT photovoltaic panels decreases and switches to mains power. When the light conditions improve, the inverter is powered by the MPPT photovoltaic panels again; (3) When the mains power is disconnected, the inverter is powered entirely by the photovoltaic power of the MPPT photovoltaic panels. As the light conditions continue to decrease, the power required by the inverter also decreases.

[0004] However, in order to save costs, communication between the MPPT board and the inverter is not set up in the existing hardware topology. As a result, the inverter cannot accurately know how the photovoltaic power supply situation changes. Once the lighting conditions change drastically, the power supplied by the MPPT photovoltaic panel will change rapidly. If no action is taken, it will cause the inverter to malfunction and shut down, resulting in a poor user experience.

[0005] Therefore, there is an urgent need to improve the control mode of existing photovoltaic systems in order to solve the control requirements under complex conditions of unstable mains power supply and changing light conditions. Summary of the Invention

[0006] The present invention provides a frequency converter control method for photovoltaic MPPT panels, which adopts fuzzy control. When the mains power supply is unstable and the lighting conditions are complex and changing, it can effectively ensure the stable operation of the compressor and the fault-free shutdown, thereby maximizing the user experience.

[0007] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0008] A frequency converter control method for photovoltaic MPPT panels includes the following steps:

[0009] S1. The program begins by sampling the voltage through the sampling circuit;

[0010] S2. Obtain Ave_Vdc and Err_Vdc;

[0011] S3. Incorporate the fuzzy PID controller and design fuzzy PID control by using Ave_Vdc and Err_Vdc as inputs to the fuzzy controller;

[0012] A simulation model was built using fuzzy control to verify the reliability of the algorithm;

[0013] S4. The algorithm is then written into the program to obtain the motor speed Wr corresponding to the frequency converter;

[0014] S5. Determine whether the motor speed Wr corresponding to the frequency converter is greater than the minimum motor speed Wr_Min corresponding to the frequency converter;

[0015] When the motor speed Wr corresponding to the frequency converter is greater than or equal to the minimum motor speed Wr_Min corresponding to the frequency converter, the frequency converter will continue to run until it ends.

[0016] When the power supplied by MPPT is insufficient to maintain the power consumed by the inverter due to changes in lighting conditions, the algorithm actively reduces the motor speed Wr corresponding to the inverter, thereby reducing the power required by the inverter and ensuring that the bus voltage will not fluctuate violently and cause a fault shutdown.

[0017] When the power supplied to the inverter by the MPPT continuously decreases to the point where it cannot meet the power required for the minimum speed of the motor corresponding to the inverter, that is, when the motor speed Wr corresponding to the inverter is less than the minimum speed Wr_Min corresponding to the inverter, the motor corresponding to the inverter will stop at the minimum speed, which will not bring a large inrush current to the inverter hardware.

[0018] Furthermore, step S3 specifically includes:

[0019] S3.1 First, the system transfer function is obtained as follows: A fuzzy PID controller was designed using MATLAB and the FUZZY editor. The input values ​​are Ave_Vdc and Err_Vdc, and the output values ​​are Kp, Ki, and Kd. Both the input and output use the triangular membership function trimf, as shown in Equation 1.

[0020] ------Formula (1)

[0021] Among them, the universe of discourse of Ave_Vdc and Err_Vdc is [-6,6], the universe of discourse of KP is [2,5], the universe of discourse of Ki is [1,3], and the universe of discourse of Kd is [7,19].

[0022] S3.2 Then, based on the fuzzy table of proportional parameter P in Table 1, the fuzzy table of integral parameter i in Table 2, and the fuzzy table of calculus parameter d in Table 3, edit the fuzzy rules;

[0023] Table 1

[0024]

[0025] Table 2

[0026]

[0027] Table 3

[0028]

[0029] In Tables 1, 2 and 3, NL represents negative large, NM represents negative medium, NS represents negative small, ZE represents zero, PS represents positive small, PM represents positive medium and PB represents positive large;

[0030] The S3.3 program provides the output of the maximum membership value to resolve fuzziness;

[0031] The element with the highest membership degree in the fuzzy set of the inference results is selected as the output value, i.e. ;

[0032] If, in the output universe of discourse V, there is more than one output value corresponding to the maximum membership degree, then the value is taken as the average of the outputs with the maximum membership degree, i.e. ;

[0033] S3.4 Then, a simulation model is built using Simulink to verify the reliability of the algorithm;

[0034] S3.5 The simulation results show that when the input power of the MPPT photovoltaic panel changes, the inverter adjusts its speed at a relatively fast rate to ensure that the power consumption basically follows the photovoltaic power supply, thus ensuring operational stability.

[0035] Another object of the present invention is to provide an information data processing terminal for implementing the inverter control method for photovoltaic MPPT boards.

[0036] Another object of the present invention is to provide a computer-readable storage medium for storing a computer program, which, when invoked by a processor, implements the inverter control method for a photovoltaic MPPT board.

[0037] Another object of the present invention is to provide an air conditioner including a processor and a memory, the memory being used to store a computer program, which, when invoked by the processor, implements the inverter control method for photovoltaic MPPT panels.

[0038] The beneficial effects of this invention are:

[0039] To address the issue of rapid power fluctuations in MPPT photovoltaic panels due to drastic changes in lighting conditions, this embodiment employs a fuzzy control mode. The bus voltage fluctuation and average value are used as inputs, with outputs KP, KI, and KD, all using triangular membership functions. A traditional PID fuzzy rule table is used to design the fuzzy controller, and parameters are adjusted according to actual conditions. This effectively ensures stable compressor operation and trouble-free shutdown under complex lighting conditions, especially when mains power supply is unstable, maximizing user experience. Furthermore, the detection method is purely software-based, eliminating the need for additional hardware detection circuits and effectively reducing control costs.

[0040] In this invention, a control algorithm is added to the inverter matched with MPPT photovoltaic panels. Addressing the issue of existing economical hardware topologies where there is no communication data transmission between the MPPT photovoltaic panel and the inverter, this control system is analyzed to establish a transfer function. Then, using Ave_Vdc and Err_Vdc as input values ​​and Kp, Ki, and Kd as output values, a fuzzy controller with a 7-membership triangular membership function is designed. The corresponding control algorithm is incorporated into the sensorless FOC algorithm, ensuring that the motor speed of the inverter adapted to the MPPT photovoltaic panel automatically changes according to the power supplied by the MPPT. This prevents the inverter from malfunctioning and shutting down due to voltage fluctuations, improving the user experience. Even if the power supplied by the MPPT photovoltaic panel is insufficient to maintain the minimum speed required for the motor, it will not cause a large inrush current, thus protecting the inverter. Specifically, by combining actual test conditions, fuzzy PID control is used to dynamically adjust the output speed of the inverter based on the bus voltage, ensuring that under complex lighting conditions, the inverter can change its power consumption according to the power supplied by the MPPT photovoltaic panel, achieving the effect of no abnormal shutdown. Attached Figure Description

[0041] Figure 1 This is a design drawing of the FUZZY editor in this invention;

[0042] Figure 2 This is the universe of discourse diagram of Err_Vdc in this invention;

[0043] Figure 3 This is the universe of discourse diagram of Ave_Vdc in this invention;

[0044] Figure 4 This is the universe of discourse diagram of KP in this invention;

[0045] Figure 5 This is the universe of discourse diagram of Ki in this invention;

[0046] Figure 6This is the universe of discourse diagram of Kd in this invention;

[0047] Figure 7 This is an editing diagram of the fuzzy rules in this invention;

[0048] Figure 8 This is a simulation model diagram built using Simulink in this invention;

[0049] Figure 9 This is a simulation result diagram using Simulink in this invention;

[0050] Figure 10 This is a waveform diagram of the sudden drop in the power supplied by the MPPT photovoltaic panel after the algorithm is written into the program in this invention;

[0051] Figure 11 This is a waveform diagram of the power required to reduce the power to the lowest operating frequency and the system shuts down without faults after the algorithm is written into the program in this invention.

[0052] Figure 12 This is the control flowchart of the present invention. Detailed Implementation

[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0054] A frequency converter control method for photovoltaic MPPT panels, such as Figure 12 As shown, it includes the following steps:

[0055] S1. The program begins by sampling the voltage through the sampling circuit;

[0056] S2. Obtain Ave_Vdc and Err_Vdc;

[0057] S3. Incorporate the fuzzy PID controller and design fuzzy PID control by using Ave_Vdc and Err_Vdc as inputs to the fuzzy controller;

[0058] S3.1 First, the system transfer function is obtained as follows: Design a fuzzy PID controller using MATLAB, such as Figure 1 As shown, using the FUZZY editor, the input values ​​are Ave_Vdc and Err_Vdc, and the output values ​​are Kp, Ki, and Kd. Both the input and output use the triangle membership function trimf, as shown in Equation 1.

[0059] ------Formula (1)

[0060] Among them, such as Figures 2 to 6 As shown, the universe of discourse for Ave_Vdc and Err_Vdc is [-6,6], the universe of discourse for KP is [2,5], the universe of discourse for Ki is [1,3], and the universe of discourse for Kd is [7,19].

[0061] S3.2 Then, as Figure 7 As shown, the fuzzy rules are edited based on the proportional parameter P fuzzy table in Table 1, the integral parameter i fuzzy table in Table 2, and the calculus parameter d fuzzy table in Table 3.

[0062] Table 1

[0063]

[0064] Table 2

[0065]

[0066] Table 3

[0067]

[0068] In Tables 1, 2 and 3, NL represents negative large, NM represents negative medium, NS represents negative small, ZE represents zero, PS represents positive small, PM represents positive medium and PB represents positive large;

[0069] The S3.3 program provides the output of the maximum membership value to resolve fuzziness;

[0070] The element with the highest membership degree in the fuzzy set of the inference results is selected as the output value, i.e. ;

[0071] If, in the output universe of discourse V, there is more than one output value corresponding to the maximum membership degree, then the value is taken as the average of the outputs with the maximum membership degree, i.e. ;

[0072] S3.4 Then, a simulation model is built using Simulink to verify the reliability of the algorithm;

[0073] S3.5 The simulation results show that when the input power of the MPPT photovoltaic panel changes, the inverter adjusts its speed at a relatively fast rate to ensure that the power consumption basically follows the photovoltaic power supply, thus ensuring operational stability.

[0074] S4. The algorithm is then written into the program to obtain the motor speed Wr corresponding to the frequency converter;

[0075] S5. Determine whether the motor speed Wr corresponding to the frequency converter is greater than the minimum motor speed Wr_Min corresponding to the frequency converter. The measured waveform is as follows: Figure 10 and Figure 11 As shown;

[0076] When the motor speed Wr corresponding to the frequency converter is greater than or equal to the minimum motor speed Wr_Min corresponding to the frequency converter, the frequency converter will continue to run until it ends.

[0077] like Figure 10 As shown, when the power supplied by MPPT is insufficient to maintain the power consumed by the inverter due to changes in lighting conditions, the above algorithm actively reduces the motor speed Wr corresponding to the inverter, thereby reducing the power required by the inverter and ensuring that the bus voltage will not fluctuate violently and cause a fault shutdown.

[0078] like Figure 11 As shown, when the power supplied to the inverter by the MPPT continuously decreases to the point where it cannot meet the power required for the minimum speed of the motor corresponding to the inverter, that is, when the motor speed Wr corresponding to the inverter is less than the minimum speed Wr_Min corresponding to the inverter, the motor corresponding to the inverter stops at the minimum speed, which will not bring a large inrush current to the inverter hardware.

[0079] In this embodiment, for the existing economical hardware topology, where there is no communication data transmission between the MPPT photovoltaic panel and the frequency converter, a transfer function is established through analysis of the control system. Then, a fuzzy controller with a 7-membership triangular membership function is designed with Ave_Vdc and Err_Vdc as input values ​​and Kp, Ki, and Kd as output values. The corresponding control algorithm is constructed and added to the sensorless FOC algorithm. By combining actual test conditions, fuzzy PID control is adopted to dynamically adjust the output speed of the frequency converter according to the bus voltage. This ensures that under complex changes in lighting conditions, the frequency converter can change its own power consumption according to the power supplied by the MPPT photovoltaic panel, achieving the effect of no abnormal fault shutdown.

[0080] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Except for the cases listed in the specific embodiments, all equivalent changes made in accordance with the shape, structure and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A frequency converter control method for photovoltaic MPPT panels, characterized in that, Includes the following steps: S1. The program begins by sampling the voltage through the sampling circuit; S2. Obtain Ave_Vdc and Err_Vdc; S3. Incorporate Ave_Vdc and Err_Vdc as inputs to the fuzzy PID controller to design fuzzy PID control. A simulation model was built using fuzzy control to verify the reliability of the algorithm; S3.1 First, the system transfer function is obtained as follows: A fuzzy PID controller was designed using MATLAB and the FUZZY editor. The input values ​​are Ave_Vdc and Err_Vdc, and the output values ​​are Kp, Ki, and Kd. Both the input and output use the triangular membership function trimf, as shown in Equation 1. ------ Official (1) Among them, the universe of discourse of Ave_Vdc and Err_Vdc is [-6,6], the universe of discourse of KP is [2,5], the universe of discourse of Ki is [1,3], and the universe of discourse of Kd is [7,19]. S3.2 Then, based on the fuzzy table of proportional parameter P in Table 1, the fuzzy table of integral parameter i in Table 2, and the fuzzy table of calculus parameter d in Table 3, edit the fuzzy rules; Table 1 Table 2 Table 3 In Tables 1, 2 and 3, NL represents negative large, NM represents negative medium, NS represents negative small, ZE represents zero, PS represents positive small, PM represents positive medium and PB represents positive large; The S3.3 program provides the output of the maximum membership value to resolve fuzziness; The element with the highest membership degree in the fuzzy set of the inference results is selected as the output value, i.e. ; If, in the output universe of discourse V, there is more than one output value corresponding to the maximum membership degree, then the value is taken as the average of the outputs with the maximum membership degree, i.e. ; S3.4 Then, a simulation model is built using Simulink to verify the reliability of the algorithm; S3.5 The simulation results show that when the input power of the MPPT photovoltaic panel changes, the inverter adjusts its speed at a relatively fast rate to ensure that the power consumption basically follows the photovoltaic power supply, thus ensuring operational stability. S4. The algorithm is then written into the program to obtain the motor speed Wr corresponding to the frequency converter; S5. Determine whether the motor speed Wr corresponding to the frequency converter is greater than the minimum motor speed Wr_Min corresponding to the frequency converter; When the motor speed Wr corresponding to the frequency converter is greater than or equal to the minimum motor speed Wr_Min corresponding to the frequency converter, the frequency converter will continue to run until it ends. When the power supplied by MPPT is insufficient to maintain the power consumed by the inverter due to changes in lighting conditions, the algorithm actively reduces the motor speed Wr corresponding to the inverter, thereby reducing the power required by the inverter and ensuring that the bus voltage will not fluctuate violently and cause a fault shutdown. When the power supplied to the inverter by the MPPT continuously decreases to the point where it cannot meet the power required for the minimum speed of the motor corresponding to the inverter, that is, when the motor speed Wr corresponding to the inverter is less than the minimum speed Wr_Min corresponding to the inverter, the motor corresponding to the inverter will stop at the minimum speed, which will not bring a large inrush current to the inverter hardware.

2. An information data processing terminal for implementing the inverter control method for photovoltaic MPPT boards as described in claim 1.

3. A computer-readable storage medium for storing a computer program, characterized in that, When the computer program is called by the processor, it implements the inverter control method for photovoltaic MPPT boards as described in claim 1.

4. An air conditioner, comprising a processor and a memory, the memory for storing a computer program, characterized in that, When the computer program is invoked by the processor, it implements the inverter control method for photovoltaic MPPT panels as described in claim 1.

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