Maximum power point tracking method, photovoltaic system and computer readable storage medium

Abstract

The application provides a maximum power point tracking method, a photovoltaic system and a computer readable storage medium. The maximum power point tracking method comprises: acquiring maximum output power of a reference photovoltaic panel through an output power detection circuit; when the maximum output power of the reference photovoltaic panel is greater than or equal to a first preset threshold, sending a first control signal to a maximum power tracking circuit, and the first control signal is used to control the maximum power tracking circuit to perform maximum power point tracking on output power of a main photovoltaic panel. The above method sets a reference photovoltaic panel with the same configuration parameters and in the same environment as the main photovoltaic panel. When the maximum output power of the reference photovoltaic panel is greater than or equal to the first preset threshold, it indicates that the environment of the main photovoltaic panel and the reference photovoltaic panel is not a weak light state. Then, the maximum power tracking circuit is controlled to start, which can avoid the problem of repeated shutdown and restart of the maximum power tracking circuit in the weak light state, thereby effectively improving the stability and reliability of the photovoltaic system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar power generation, and in particular to a maximum power point tracking method, a photovoltaic system and a computer readable storage medium. BACKGROUND

[0002] In the working process of the photovoltaic system, when in the time period of overcast days, morning sunrise and evening sunset, due to low light radiation intensity (weak light state), the power generation capacity of the photovoltaic panel will be reduced, and the output power of the photovoltaic panel is insufficient. Further, in the process of tracking the maximum power of the photovoltaic panel, the MPPT (Maximum Power Point Tracking) circuit connected to the photovoltaic panel will pull down the output voltage of the photovoltaic panel, resulting in that the voltage at the input end of the MPPT circuit is lower than the under-voltage protection threshold, so that the MPPT circuit generates under-voltage protection, thereby stopping the power tracking of the photovoltaic panel. After the output voltage of the photovoltaic panel recovers to the voltage before being pulled down, the MPPT circuit removes the under-voltage protection, and the MPPT circuit re-tracks the maximum power. Such repeated stopping and restarting of the photovoltaic system (shutdown and restart) will reduce the stability and reliability of the photovoltaic system. SUMMARY

[0003] The main purpose of the present application is to provide a maximum power point tracking method, a photovoltaic system and a computer readable storage medium, which aims to solve the problem of repeated stopping and restarting of the photovoltaic system in the weak light state, so as to improve the stability and reliability of the photovoltaic system.

[0004] The first aspect of the present application provides a maximum power point tracking method applied to a photovoltaic system, the photovoltaic system comprising a main photovoltaic panel, a reference photovoltaic panel, a maximum power tracking circuit and an output power detection circuit; the maximum power tracking circuit is connected with the main photovoltaic panel; the output power detection circuit is connected with the reference photovoltaic panel; the reference photovoltaic panel and the main photovoltaic panel have the same configuration parameters and are in the same environment; the maximum power point tracking method comprises: acquiring the maximum output power of the reference photovoltaic panel through the output power detection circuit; when the maximum output power of the reference photovoltaic panel is greater than or equal to a first preset threshold, sending a first control signal to the maximum power tracking circuit, the first control signal being used to control the maximum power tracking circuit to track the maximum power point of the output power of the main photovoltaic panel.

[0005] In the maximum power point tracking method provided in this application, a reference photovoltaic panel with the same configuration parameters and in the same environment as the main photovoltaic panel is set, and the output power of the reference photovoltaic panel and the main photovoltaic panel have a certain proportional relationship. The maximum output power of the reference photovoltaic panel is obtained by the output power detection circuit. When the maximum output power of the reference photovoltaic panel is greater than or equal to a first preset threshold, the maximum output power of the main photovoltaic panel is also greater than or equal to a certain threshold. If the first preset threshold is set as the critical value for determining whether the reference photovoltaic panel is in a low light state, then when the maximum output power of the reference photovoltaic panel is greater than or equal to the first preset threshold, it indicates that the environment in which the main photovoltaic panel and the reference photovoltaic panel are located is not a low light state. At this time, a first control signal is sent to the maximum power tracking circuit to start the maximum power point tracking of the output power of the main photovoltaic panel. In other words, the maximum output power of the reference photovoltaic panel can be determined first. Once the maximum output power of the reference photovoltaic panel is greater than the first preset threshold, and it is confirmed that the main photovoltaic panel and the reference photovoltaic panel are not in a low light state, the maximum power point tracking circuit is then started to track the maximum power point of the output power of the main photovoltaic panel. This can avoid the problem of the maximum power tracking circuit repeatedly stopping and restarting tracking under low light conditions, thereby effectively improving the stability and reliability of the photovoltaic system.

[0006] In one embodiment, the maximum power point tracking method further includes: obtaining a power reference value of the maximum output power of the main photovoltaic panel based on the maximum output power of the reference photovoltaic panel; obtaining the actual maximum output power value of the main photovoltaic panel obtained by the maximum power point tracking circuit after performing maximum power point tracking on the output power of the main photovoltaic panel; and determining that the photovoltaic system has failed if the power difference between the power reference value and the actual maximum output power value is greater than or equal to a preset difference threshold.

[0007] In one embodiment, obtaining a power reference value for the maximum output power of the main photovoltaic panel based on the maximum output power of a reference photovoltaic panel includes: multiplying the maximum output power of the reference photovoltaic panel by a preset multiple to obtain the power reference value for the maximum output power of the main photovoltaic panel; wherein the preset multiple is positively correlated with the ratio between the rated output power of the main photovoltaic panel and the rated output power of the reference photovoltaic panel.

[0008] In one embodiment, the photovoltaic system further includes an energy storage device connected to the maximum power tracking circuit; after the step of sending a first control signal to the maximum power tracking circuit, the maximum power tracking method further includes: obtaining the minimum charging power of the energy storage device;

[0009] If the minimum charging power is less than or equal to the power reference value, a charging control signal is output. The charging control signal is used to control the maximum power tracking circuit to charge the energy storage device.

[0010] In an embodiment, the photovoltaic system further comprises an inverter circuit; an input of the inverter circuit is connected to an output of the maximum power tracking circuit; an output of the inverter circuit is connected to a load; after the step of sending the first control signal to the maximum power tracking circuit, the maximum power tracking method further comprises: obtaining a demand power of the load; if the demand power is less than or equal to the power reference value, outputting a power supply control signal, the power supply control signal being used to control the inverter circuit to discharge the load after converting the output voltage of the maximum power tracking circuit.

[0011] In an embodiment, the maximum power tracking method further comprises: if the demand power is greater than the power reference value, generating a supplementary power supply control signal to the energy storage device according to a power difference between the demand power and the power reference value; the supplementary power supply control signal being used to control the energy storage device to output an electrical signal with the power difference.

[0012] The second aspect of the present application provides a photovoltaic system, the photovoltaic system comprising a main photovoltaic panel, a reference photovoltaic panel, a maximum power tracking circuit, an output power detection circuit, and a controller; the maximum power tracking circuit being connected to the main photovoltaic panel; the output power detection circuit being connected to the reference photovoltaic panel; the reference photovoltaic panel and the main photovoltaic panel having the same configuration parameters and being in the same environment; the controller being used to execute the maximum power point tracking method as described above.

[0013] In an embodiment, the output power detection circuit comprises a voltage dividing unit and a sampling unit; the voltage dividing unit comprising a plurality of voltage dividing branches connected to the reference photovoltaic panel; each voltage dividing branch comprising a voltage dividing resistor and a switch; the voltage dividing resistors of the voltage dividing branches being different; the sampling unit being used to collect an output voltage of the reference photovoltaic panel; the controller being further used to sequentially turn on the voltage dividing branches to obtain the output power in different states through the sampling unit and determine the maximum output power of the reference photovoltaic panel.

[0014] In an embodiment, the sampling unit comprises a first sampling resistor, a second sampling resistor, a third sampling resistor, and a filter capacitor; one end of the first sampling resistor being connected to the reference photovoltaic panel, the other end of the first sampling resistor being connected to one end of the second sampling resistor, the other end of the second sampling resistor being grounded, one end of the third sampling resistor being connected between the first sampling resistor and the second sampling resistor, the other end of the third sampling resistor being connected to the controller, one end of the filter capacitor being connected to the other end of the third sampling resistor, the other end of the filter capacitor being grounded; the controller being used to: obtain a node voltage of a connection node between the third sampling resistor and the filter capacitor, calculate the output voltage according to the node voltage and a proportional relationship of resistances of the first sampling resistor and the second sampling resistor; calculate the output power according to the output voltage and a resistance of the voltage dividing resistor of the turned-on voltage dividing branch.

[0015] The third aspect of the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the maximum power point tracking method as described above. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a circuit topology diagram of a photovoltaic system in the related art.

[0017] Figure 2 is a module diagram of a photovoltaic system provided by an embodiment of the present application.

[0018] Figure 3 is a circuit schematic diagram of an output power detection circuit provided by an embodiment of the present application.

[0019] Figure 4 is a module diagram of a photovoltaic system provided by another embodiment of the present application.

[0020] Figure 5 is a flowchart of a maximum power point tracking method provided by an embodiment of the present application.

[0021] Figure 6 is a partial flowchart of a maximum power point tracking method provided by another embodiment of the present application.

[0022] Figure 7 is a partial flowchart of a maximum power point tracking method provided by yet another embodiment of the present application.

[0023] Figure 8 is a partial flowchart of a maximum power point tracking method provided by still another embodiment of the present application.

[0024] Figure 9 is a schematic diagram of a connection relationship between a maximum power point tracking control device 200 and a photovoltaic system 10 according to an embodiment of the present application.

[0025] MAIN ELEMENT SYMBOL EXPLANATION

[0026] Photovoltaic system 1

[0027] Main photovoltaic panel 10

[0028] Reference photovoltaic panel 20

[0029] Maximum power tracking circuit 30

[0030] Output power detection circuit 40

[0031] Voltage dividing unit 41

[0032] Voltage dividing branch 410

[0033] Voltage dividing resistors R1, R2, R3, …, Rn

[0034] Switches S1, S2, S3, …, Sn

[0035] Sampling unit 42

[0036] First sampling resistor R40

[0037] Second sampling resistor R41

[0038] Third sampling resistor R42

[0039] Filter capacitor C1

[0040] Controller 50

[0041] Energy storage device 60

[0042] Inverter circuit 70

[0043] Maximum power point tracking control device 200

[0044] Processing module 210

[0045] Control module 220

[0046] The following detailed description will further illustrate the present application in conjunction with the above-mentioned figures. DETAILED DESCRIPTION

[0047] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the accompanying drawings are used to distinguish similar objects, and are not intended to describe a specific order or sequence.

[0048] In addition, it should be noted that the methods disclosed in the embodiments of the present application or shown in the flowcharts include one or more steps for implementing the methods, and the execution order of the steps can be interchanged with each other without departing from the scope of the claims, and some steps can also be deleted.

[0049] Some embodiments will be described below in conjunction with the accompanying drawings. The following embodiments and features in the embodiments can be combined with each other without conflict.

[0050] Please refer to Figure 1 , Figure 1 The circuit topology of the photovoltaic system shown includes a photovoltaic panel, an MPPT (Maximum Power Point Tracking) circuit, an energy storage circuit, and an inverter circuit. The photovoltaic panel is used to convert solar energy into electrical energy. The MPPT circuit is used to detect the power generation voltage of the photovoltaic panel in real time, and track the highest voltage and current value, so that the photovoltaic system outputs maximum power to charge the energy storage circuit or supply power to the grid and external loads through the inverter circuit.

[0051] When in the period of weak light state such as overcast day, morning sunrise and evening sunset, the power generation capability of the photovoltaic panel is reduced, and thus the output power of the photovoltaic panel is reduced. However, due to the characteristics of the photovoltaic panel, when the output power is low, the open circuit voltage of the photovoltaic panel is still relatively large. Therefore, the MPPT circuit detects the open circuit voltage of the photovoltaic panel, and starts to supply power to the subsequent circuit, such as charging the energy storage circuit of the subsequent stage, or supplying power to the grid or load through the inverter circuit. However, the output power of the photovoltaic panel is too low, and the power consumption of the start of the MPPT circuit will cause the output voltage of the photovoltaic panel to be pulled down, resulting in that the voltage at the input end of the MPPT circuit is lower than the under-voltage protection threshold, so that the MPPT circuit generates under-voltage protection, and the MPPT circuit stops supplying power to the subsequent circuit. At this time, the output end of the photovoltaic panel restores to open circuit, the open circuit voltage is increased, and after the MPPT circuit detects the higher open circuit voltage, the MPTT circuit starts to supply power to the subsequent circuit again, and the output voltage of the photovoltaic panel is pulled down again. Thus, the photovoltaic panel is repeatedly started and stopped, which affects the service life of the photovoltaic panel and reduces the stability and reliability of the photovoltaic system.

[0052] Therefore, the embodiment of the present application provides a photovoltaic system and a maximum power point tracking method thereof, which can prevent the maximum power tracking circuit from repeatedly stopping working and restarting tracking in the case of weak light, and improve the stability and reliability of the photovoltaic system.

[0053] Please refer to Figure 2 , Figure 2 The module schematic diagram of the photovoltaic system 100 provided by the embodiment of the present application is shown.

[0054] As shown in Figure 2 , the photovoltaic system 100 includes a main photovoltaic panel 10, a reference photovoltaic panel 20, a maximum power tracking circuit 30, an output power detection circuit 40 and a controller 50.

[0055] The maximum power tracking circuit 30 is connected with the main photovoltaic panel 10, and the maximum power tracking circuit 30 is used for maximum power point tracking of the output power of the main photovoltaic panel 10. The output power detection circuit 40 is connected with the reference photovoltaic panel 20. The reference photovoltaic panel 20 and the main photovoltaic panel 10 have the same configuration parameters and are in the same environment.

[0056] In the embodiment of the present application, the reference photovoltaic panel 20 and the main photovoltaic panel 10 having the same configuration parameters means that the installation angle, installation direction and the like of the reference photovoltaic panel 20 and the main photovoltaic panel 10 are consistent, and there is no shelter to shelter the reference photovoltaic panel 20 or the main photovoltaic panel 10. That is, the conditions affecting the illumination of the reference photovoltaic panel 20 and the main photovoltaic panel 10 are consistent. The reference photovoltaic panel 20 and the main photovoltaic panel 10 are set to the same configuration parameters and are in the same environment, which can ensure that the reference photovoltaic panel 20 and the main photovoltaic panel 10 can receive the same light intensity.

[0057] The controller 50 acquires the maximum output power of the reference photovoltaic panel 20 through the output power detection circuit 40. When the maximum output power of the reference photovoltaic panel 20 is greater than or equal to a first preset threshold, the controller 50 sends a first control signal to the maximum power tracking circuit 30, and the maximum power tracking circuit 30 performs maximum power point tracking on the output power of the main photovoltaic panel 10 according to the first control signal.

[0058] In the embodiment of the present application, the first preset threshold refers to a critical value for judging whether the reference photovoltaic panel 20 is in a weak light state when the reference photovoltaic panel 20 is detected in weak light. When the maximum output power of the reference photovoltaic panel 20 is greater than or equal to the first preset threshold, the reference photovoltaic panel 20 is in a strong light state, or the reference photovoltaic panel 20 is not in a weak light state. When the maximum output power of the reference photovoltaic panel 20 is less than the first preset threshold, the reference photovoltaic panel 20 is in a weak light state.

[0059] It can be understood that, since the main photovoltaic panel 10 and the reference photovoltaic panel 20 have the same configuration parameters and are in the same environment, when the reference photovoltaic panel 20 is in a weak light state, the main photovoltaic panel 10 is also in a weak light state. When the reference photovoltaic panel 20 is in a strong light state or not in a weak light state, the main photovoltaic panel 10 is also in a strong light state or not in a weak light state.

[0060] Therefore, in the photovoltaic system 100 of the embodiment of the present application, the controller 50 acquires the maximum output power of the reference photovoltaic panel 20 through the output power detection circuit 40, and when the maximum output power of the reference photovoltaic panel 20 is greater than or equal to the first preset threshold, it indicates that the reference photovoltaic panel 20 and the main photovoltaic panel 10 are not in a weak light state, and the controller 50 sends a first control signal to control the maximum power tracking circuit 30 to perform maximum power point tracking on the output power of the main photovoltaic panel 10. That is, the controller 50 controls the maximum power tracking circuit 30 to start only when it is confirmed that the main photovoltaic panel 10 is not in a weak light state, and when the main photovoltaic panel 10 is in a weak light state, the maximum power tracking circuit 30 does not work, thereby preventing the maximum power tracking circuit 30 from repeatedly shutting down and restarting in a weak light state, and improving the stability and reliability of the photovoltaic system 100.

[0061] Please refer to Figure 3 , Figure 3 The circuit schematic diagram of the output power detection circuit 40 of the embodiment of the present application is shown.

[0062] As shown in Figure 3 , the output power detection circuit 40 includes a voltage dividing unit 41 and a sampling unit 42.

[0063] Voltage divider unit 41 includes multiple voltage divider branches 410 connected to the reference photovoltaic panel 20. Each voltage divider branch 410 includes a voltage divider resistor and a switch; the voltage divider resistor values ​​of each voltage divider branch 410 are different. Sampling unit 42 is used to acquire the output voltage of the reference photovoltaic panel 20. Figure 3 PV0 is shown as the positive terminal of the output terminal of the reference photovoltaic panel 20, and GND is the negative terminal of the output terminal of the reference photovoltaic panel 20.

[0064] Combination Figure 2 and Figure 3 As shown, the controller 50 can also be used to sequentially turn on each voltage divider branch 410 to obtain the output power under different states through the sampling unit 42 and determine the maximum output power of the reference photovoltaic panel 20.

[0065] It is understood that the controller 50 can sequentially control the switching of each voltage divider branch 410, so that the output terminal of the reference photovoltaic panel 20 is connected to different resistive loads, thereby obtaining the output power of the reference photovoltaic panel 20 under different resistive loads. In this application, the switches of each voltage divider branch 410 can be configured as controllable switches, such as relays, switching transistors, etc.

[0066] The sampling unit 42 includes a first sampling resistor R40, a second sampling resistor R41, a third sampling resistor R42, and a filter capacitor C1. One end of the first sampling resistor R40 is connected to the reference photovoltaic panel 20, and the other end of the first sampling resistor R40 is connected to one end of the second sampling resistor R41, with the other end of the second sampling resistor R41 grounded. One end of the third sampling resistor R42 is connected between the first sampling resistor R40 and the second sampling resistor R41, and the other end of the third sampling resistor R42 is connected to the controller 50. One end of the filter capacitor C1 is connected to the other end of the third sampling resistor R42, and the other end of the filter capacitor C1 is grounded.

[0067] Controller 50 is used to obtain the node voltage V0 (e.g., between the third sampling resistor R42 and the filter capacitor C1) of the connection node. Figure 3 (As shown). The controller 50 calculates the output voltage of the reference photovoltaic panel 20 based on the ratio of the acquired node voltage V0 to the resistance values ​​of the first sampling resistor R40 and the second sampling resistor R41. Furthermore, the controller 50 calculates the output power of the reference photovoltaic panel 20 based on the calculated output voltage and the resistance values ​​of the voltage divider resistors in the conducting voltage divider branch 410.

[0068] Specifically, the voltage dividing unit 41 includes n voltage dividing branches 410, the first voltage dividing branch 410 includes a voltage dividing resistor R1 and a switch S1, the second voltage dividing branch 410 includes a voltage dividing resistor R2 and a switch S2, and the nth voltage dividing branch 410 includes a voltage dividing resistor Rn and a switch Sn. In the sampling unit 42, the ratio of the resistance values of the first sampling resistor R40 and the second sampling resistor R41 is M. The specific steps of the controller 50 for sequentially turning on the voltage dividing branches 410 are described in detail below.

[0069] The controller 50 first controls the switch S1 of the first voltage dividing branch 410 to be turned on, and the controller 50 collects the current node voltage V01, and calculates the first output voltage V1 of the reference photovoltaic panel 20 according to the current node voltage V01 and the ratio M, where V1=(1+M)*V01. The controller 50 calculates the first output power P1 of the reference photovoltaic panel 20 according to the calculated first output voltage V1 and the resistance value of the voltage dividing resistor R1 of the first voltage dividing branch 410, where P1=V1*V1 / R1.

[0070] Then the controller 50 controls the switch S1 of the first voltage dividing branch 410 to be continuously turned on, and controls the switch S2 of the second voltage dividing branch 410 to be turned on. The controller 50 also collects the current node voltage V02, and calculates the second output voltage V2 of the reference photovoltaic panel 20 according to the current node voltage V02 and the ratio M, where V2=(1+M)*V02. The controller 50 calculates the second output power P2 of the reference photovoltaic panel 20 according to the calculated second output voltage V2 and the resistance values of the voltage dividing resistors R1 and R2 of the first and second voltage dividing branches 410, where P2=V2*V2 / (R1 / / R2).

[0071] The controller 50 continues to control the switches S1 and S2 of the first and second voltage dividing branches 410 to be continuously turned on, and controls the switch S3 of the third voltage dividing branch 410 to be turned on, and also collects the current node voltage V03, and calculates the third output voltage V3 of the reference photovoltaic panel 20 according to the current node voltage V03 and the ratio M, where V3=(1+M)*V03. The controller 50 calculates the third output power P3 of the reference photovoltaic panel 20 according to the calculated third output voltage V3 and the resistance values of the voltage dividing resistors R1, R2 and R3 of the three turned-on voltage dividing branches 410, where P3=V3*V3 / (R1 / / R2 / / R3).

[0072] Further, the controller 50 compares the first output power P1 and the second output power P2, and compares the second output power P2 and the third output power P3. If the comparison result is P1 < P2 and P2 > P3, P2 is the maximum output power of the reference photovoltaic panel 20. If the comparison result is not this, the controller 50 continues to turn on the switches of the remaining voltage division branches 410 in the above manner. Each time one voltage division branch 410 is added, the controller 50 calculates the output power of the corresponding reference photovoltaic panel 20, compares the output power Pi-1 of the first number of voltage division branches 410 turned on last time with the output power Pi of the second number of voltage division branches 410 turned on this time, and confirms whether Pi > Pi-1 and Pi > Pi+1 are satisfied. If satisfied, it is confirmed that Pi is the maximum output power of the reference photovoltaic panel 20. Wherein the first number is different from the second number.

[0073] It can be understood that each time the controller 50 controls to turn on the switch of one voltage division branch 410, it needs to last for a certain period of time (for example, 10us, 20us, 30us, etc.), and in this period of time, the controller 50 calculates the current output power of the reference photovoltaic panel 20 according to the above manner, and then controls to turn on the switch of another voltage division branch 410. The time period required for the controller 50 to control the switch S1 of the first voltage division branch 410 to turn on to the switch Sn of the last voltage division branch 410 to turn on is very short, for example, 2S, 3S, 5S, etc. In this period of time, the light intensity of the environment where the reference photovoltaic panel 20 is located hardly changes. That is to say, the controller 50 turns on each voltage division branch 410 in turn, and calculates the output power of the reference photovoltaic panel 20 corresponding to each time one voltage division branch 410 is added to turn on, so as to calculate the output power of the reference photovoltaic panel 20 connected with different resistance loads under the same light intensity, compare each output power calculated, and then obtain the maximum output power of the reference photovoltaic panel 20 under the light intensity.

[0074] The controller 50 repeatedly turns on each voltage division branch 410 in turn, and compares the maximum output power of the reference photovoltaic panel 20 under the current light with the first preset threshold value. When the maximum output power is greater than or equal to the first preset threshold value, it indicates that the reference photovoltaic panel 20 is not in a weak light state at this time.

[0075] In some embodiments, the controller 50 can control all the switches of the voltage division branches 410 to be turned off for a certain period of time after completing the turning on of each voltage division branch 410 in turn once, and then turn on each voltage division branch 410 in turn again.

[0076] In this embodiment, the output power detection circuit 40 has a simple circuit structure and only uses some resistors and switches, which can reduce the cost and complexity of the output power detection circuit 40.

[0077] In some embodiments, such as Figure 4 As shown, the photovoltaic system 100 may also include an energy storage device 60 connected to the maximum power point tracking (MPPT) circuit 30. When the MPPT circuit 30 is activated, that is, when the main photovoltaic panel 10 is not in a low-light state, the output power of the main photovoltaic panel 10 supplies power to the energy storage device 60 through the MPPT circuit 30. Thus, the output power of the main photovoltaic panel 10 can be stored in the energy storage device 60, and when the main photovoltaic panel 10 is in a low-light state, the photovoltaic system 100 can use the stored power in the energy storage device 60 to supply power to connected loads.

[0078] Please continue reading. Figure 4 In some embodiments, the photovoltaic system 100 further includes an inverter circuit 70. The input terminal of the inverter circuit 70 is connected to the output terminal of the maximum power point tracking circuit 30, and the output terminal of the inverter circuit 70 is connected to a load. Based on this, the electrical energy output from the main photovoltaic panel 10 is output to the inverter circuit 70 via the maximum power point tracking circuit 30, converted into alternating current by the inverter circuit 70, and then used to power the load.

[0079] Please refer to the conclusion. Figure 5 , Figure 5 This is a flowchart illustrating the maximum power point tracking method provided in an embodiment of this application. In at least one embodiment, the maximum power point tracking method is applied to the photovoltaic system 100 as described above, and the maximum power point tracking method can be executed by the aforementioned controller 50.

[0080] Specifically, the maximum power point tracking method may include the following steps S10 to S20, and combined with Figure 4 The following is a schematic diagram of the photovoltaic system 100, and the steps are described below.

[0081] S10. Obtain the maximum output power of the reference photovoltaic panel through the output power detection circuit.

[0082] The specific circuit of the output power detection circuit 40 and the method of obtaining the maximum output power through the output power detection circuit 40 are as described in the photovoltaic system 100 above, and will not be repeated here.

[0083] S20. When the maximum output power of the reference photovoltaic panel is greater than or equal to the first preset threshold, a first control signal is sent to the maximum power point tracking circuit. The first control signal is used to control the maximum power point tracking circuit to perform maximum power point tracking on the output power of the main photovoltaic panel.

[0084] Since the reference photovoltaic panel 20 and the main photovoltaic panel 10 have the same configuration parameters and are in the same environment, the output powers of the reference photovoltaic panel 20 and the main photovoltaic panel 10 have a certain proportional relationship. When the maximum output power of the reference photovoltaic panel 20 is greater than or equal to a first preset threshold, it indicates that the maximum output power of the main photovoltaic panel 10 is also greater than or equal to a certain preset threshold. If the first preset threshold is set as the critical value for judging whether the reference photovoltaic panel 20 is in a weak light state, when the maximum output power of the reference photovoltaic panel 20 is greater than or equal to the first preset threshold, it indicates that the reference photovoltaic panel 20 is not in a weak light state, and similarly, the main photovoltaic panel 10 is also not in a weak light state. At this time, the first control signal can be sent to the maximum power tracking circuit 30, so that the maximum power tracking circuit 30 performs maximum power point tracking on the output power of the main photovoltaic panel 10. When the maximum output power of the reference photovoltaic panel 20 is less than the first preset threshold, it indicates that the reference photovoltaic panel 20 and the main photovoltaic panel 10 are both in a weak light state, at this time, the maximum power tracking circuit 30 is not started to perform maximum power tracking on the output power of the main photovoltaic panel 10. Therefore, the maximum power tracking method of the present application can make the maximum power tracking circuit 30 not start in the weak light state of the main photovoltaic panel 10, and confirm that the main photovoltaic panel 10 is not in a weak light state to start the maximum power tracking circuit 30, thereby effectively preventing the maximum power tracking circuit 30 from repeatedly shutting down and restarting in a weak light state, and improving the stability and reliability of the photovoltaic system 100.

[0085] In some embodiments, as shown in FIG. 1, Figure 6 The maximum power tracking method can further include steps S30-S32. Specifically, steps S30-S32 are described in combination with the photovoltaic system 100 in FIG. 1. Figure 4

[0086] S30, according to the maximum output power of the reference photovoltaic panel, obtaining the power reference value of the maximum output power of the main photovoltaic panel.

[0087] Since the main photovoltaic panel 10 and the reference photovoltaic panel 20 have the same configuration parameters and are in the same environment, the output powers of the main photovoltaic panel 10 and the reference photovoltaic panel 20 have a certain proportional relationship, and the maximum output power of the reference photovoltaic panel 20 and the proportional relationship can be calculated to obtain the power reference value of the maximum output power of the main photovoltaic panel 10.

[0088] ​Specifically, the power reference value of the maximum output power of the main photovoltaic panel 10 can be obtained by multiplying the maximum output power of the reference photovoltaic panel 20 by a preset multiple. The preset multiple is in a positive correlation with the ratio between the rated output power of the main photovoltaic panel 10 and the rated output power of the reference photovoltaic panel 20. For example, the ratio between the rated output power of the main photovoltaic panel 10 and the rated output power of the reference photovoltaic panel 20 is 5, and the preset multiple can also be 5 times. When the maximum output power of the reference photovoltaic panel 20 is 3 W, the power reference value of the maximum output power of the main photovoltaic panel 10 is obtained by multiplying the maximum output power 3 W of the reference photovoltaic panel 20 by the preset multiple (5 times), which is 15 W. When the maximum output power of the reference photovoltaic panel 20 is 10 W, the power reference value of the maximum output power of the main photovoltaic panel 10 is obtained by multiplying the maximum output power 10 W of the reference photovoltaic panel 20 by the preset multiple (5 times), which is 50 W. Of course, the preset multiple is not limited to this in the embodiment of the present application, and the preset multiple is set according to the ratio between the rated output power of the reference photovoltaic panel 20 and the rated output power of the main photovoltaic panel 10 actually set in the photovoltaic system 100.

[0089] S31, obtaining an actual maximum output power value of the main photovoltaic panel after the maximum power point tracking circuit tracks the output power of the main photovoltaic panel.

[0090] The actual maximum output power refers to the maximum output power of the main photovoltaic panel 10 when the main photovoltaic panel 10 actually works.

[0091] S32, if the power difference between the power reference value and the actual maximum output power value is greater than or equal to a preset difference threshold, it is determined that the photovoltaic system fails.

[0092] That is, in the embodiment, after the maximum power point tracking circuit 30 tracks the output power of the main photovoltaic panel 10, the maximum output power of the reference photovoltaic panel 20 can continue to be obtained by the output power detection circuit 40, and the power reference value of the maximum output power of the main photovoltaic panel 10 can be calculated according to the maximum output power of the reference photovoltaic panel 20.

[0093] In theory, the actual maximum output power of the main photovoltaic panel 10 and the calculated power reference value are consistent. However, in practice, due to the sampling error of the controller 50, there is a certain power difference between the actual output power of the main photovoltaic panel 10 and the power reference value. If the power difference is less than the difference threshold, it means that the photovoltaic system 100 is normal. Otherwise, it means that the photovoltaic system 100 fails. The failure of the photovoltaic system 100 can be that dust or other obstructions are generated on the surface of the main photovoltaic panel 10 or the reference photovoltaic panel 20, so that the illumination conditions of the main photovoltaic panel 10 and the reference photovoltaic panel 20 cannot be kept consistent, and thus the illumination intensity received by the main photovoltaic panel 10 and the reference photovoltaic panel 20 is different.

[0094] Of course, the fault of the photovoltaic system 100 is not limited to this, for example, it can also be that the main photovoltaic panel 10 or the reference photovoltaic panel 20 produces damage, resulting in the efficiency of the main photovoltaic panel 10 or the reference photovoltaic panel 20 in converting light energy into electrical energy being reduced, so that the power difference between the actual output power of the main photovoltaic panel 10 and the power reference value is greater than the difference threshold value. For another example, it can also be that the maximum power tracking circuit 30 produces a fault, so that the actual maximum output power output by the main photovoltaic panel 10 after maximum power point tracking by the maximum power tracking circuit 30 is abnormal.

[0095] In some embodiments, as shown in FIG. 6, after step S20, the maximum power tracking method further includes the following steps S40 and S41. Specifically, steps S30 to S32 are described in combination with the photovoltaic system 100 schematic diagram in FIG. 1. Figure 7 Figure 4 In some embodiments, as shown in FIG. 6, after step S20, the maximum power tracking method further includes the following steps S40 and S41. Specifically, steps S30 to S32 are described in combination with the photovoltaic system 100 schematic diagram in FIG. 1.

[0096] S40, obtaining the minimum charging power of the energy storage device.

[0097] The minimum charging power refers to the minimum power required to be provided to the energy storage device 60 when charging the energy storage device 60.

[0098] S41, if the minimum charging power is less than or equal to the power reference value, outputting a charging control signal. The charging control signal is used to control the maximum power tracking circuit to charge the energy storage device.

[0099] When the minimum charging power is less than or equal to the power reference value of the maximum output power of the main photovoltaic panel 10, it indicates that the output power of the main photovoltaic panel 10 can meet the charging of the energy storage device 60, so as to output the charging control signal to control the maximum power tracking circuit 30 to charge the energy storage device 60. When the minimum charging power is greater than the power reference value, it indicates that the output power of the main photovoltaic panel 10 is insufficient to charge the energy storage device 60, so the energy storage device 60 is not charged at this time.

[0100] In some other embodiments, as shown in FIG. 7, after step S20, the maximum power tracking method further includes the following steps S50, S51 and S52. Specifically, steps S30 to S32 are described in combination with the photovoltaic system 100 schematic diagram in FIG. 1. Figure 8 Figure 4 In some embodiments, as shown in FIG. 6, after step S20, the maximum power tracking method further includes the following steps S40 and S41. Specifically, steps S30 to S32 are described in combination with the photovoltaic system 100 schematic diagram in FIG. 1.

[0101] S50, obtaining the demand power of the load.

[0102] S51, if the demand power is less than or equal to the power reference value, outputting a power supply control signal. The power supply control signal is used to control the inverter circuit to convert the output voltage of the maximum power tracking circuit to supply power to the load.

[0103] ​​If the power demand of the load is less than or equal to the power reference value of the maximum output power of the main photovoltaic panel 10, it means that the output power of the main photovoltaic panel 10 can support the power demand of the load. Then, the power supply control signal controls the inverter circuit 70 to convert the DC power output of the maximum power tracking circuit 30 into AC power, so that the photovoltaic panel supplies power to the load.

[0104] Furthermore, the maximum power point tracking method may also include:

[0105] S52. If the required power is greater than the power reference value, a supplementary power supply control signal is generated and sent to the energy storage device based on the power difference between the required power and the power reference value. The supplementary power supply control signal is used to control the energy storage device to output an electrical signal with the power difference.

[0106] When the output power of the main photovoltaic panel 10 cannot support the power demand of the load, the energy storage device 60 and the photovoltaic panel need to work together to supply power to the load. Therefore, the output power of the energy storage device 60 can be controlled by the supplementary power supply control signal to be the power difference between the power demand of the load and the power reference value of the main photovoltaic panel 10, so that the sum of the output power of the energy storage device 60 and the main photovoltaic panel 10 can meet the power demand of the load.

[0107] In some other embodiments, if the load is connected to both the photovoltaic system 100 and the AC power grid, and the sum of the output power of the main photovoltaic panel 10 and the energy storage device 60 cannot meet the power demand of the load, then the main photovoltaic panel 10, the energy storage device 60 and the AC power grid can jointly output electrical energy to supply power to the load.

[0108] In some other embodiments, the energy storage device 60 may also be set with a maximum discharge power, which is less than the actual maximum power that the energy storage device 60 can output. For example, if the actual maximum power output of the energy storage device 60 is 2000W, but its maximum discharge power is set to 1000W, then the energy storage device 60 can only output a maximum discharge power of 1000W. In this case, if the sum of the maximum discharge power set by the energy storage device 60 and the output power of the main photovoltaic panel 10 cannot meet the power demand of the load, the main photovoltaic panel 10, the energy storage device 60, and the AC grid can jointly output electrical energy to supply power to the load.

[0109] This application also provides a maximum power point tracking control device 200, such as Figure 9 As shown, Figure 9 A schematic diagram showing the connection relationship between the maximum power point tracking control device 200 and the photovoltaic system 10 according to an embodiment of this application is illustrated. The maximum power point tracking control device 200 includes a processing module 210 and a control module 220 connected to the processing module 210. The processing module 210 is connected to the output power detection circuit 40, and the control module 220 is connected to the maximum power tracking circuit 30.

[0110] The processing module 210 is configured to acquire the maximum output power of the reference photovoltaic panel 20 through the output power detection circuit 40. The control module 220 is configured to receive the maximum output power acquired by the processing module 210, and send a first control signal to the maximum power tracking circuit 30 to control the maximum power tracking circuit 30 to perform maximum power point tracking on the output power of the main photovoltaic panel 10 when the maximum output power is greater than or equal to a first preset threshold.

[0111] Further, the control module 220 can further include a first acquisition unit, a second acquisition unit and a control unit (not shown in the figure), the first acquisition unit is connected with the output power detection circuit 40, the second acquisition unit is connected with the maximum power tracking circuit 30, and the control unit is connected with the first acquisition unit and the second acquisition unit respectively.

[0112] The first acquisition unit can acquire the power reference value of the maximum output power of the main photovoltaic panel 10 according to the maximum output power of the reference photovoltaic panel 20. The second acquisition unit can acquire the actual maximum output power value of the main photovoltaic panel 10 after the maximum power tracking circuit 30 performs maximum power point tracking on the output power of the main photovoltaic panel 10. The comparison unit is configured to compare the power reference value of the maximum output power of the main photovoltaic panel 10 with the actual maximum output power, and determine that the photovoltaic system 100 fails when the power difference between the power reference value and the actual maximum output power value is greater than or equal to a preset difference threshold.

[0113] Specifically, the first acquisition unit can obtain the reference value of the maximum output power of the main photovoltaic panel 10 by multiplying the maximum output power of the reference photovoltaic panel 20 by a preset multiple. The preset multiple is in a positive correlation with the ratio between the rated output power of the main photovoltaic panel 10 and the rated output power of the reference photovoltaic panel 20.

[0114] In some embodiments, the control module 220 can also be configured to acquire the minimum charging power of the energy storage device 60, and compare the minimum charging power with the power reference value of the maximum output power of the main photovoltaic panel 10. When the minimum charging power is less than or equal to the power reference value, the control module 220 outputs a charging control signal to control the maximum power tracking circuit 30 to charge the energy storage device 60.

[0115] In some embodiments, the control module 220 can also be configured to acquire the demand power of the load, and compare the demand power with the power reference value of the maximum output power of the main photovoltaic panel 10. When the demand power is less than or equal to the power reference value, the control module 220 outputs a power supply control signal to control the inverter circuit 70 to convert the output voltage of the maximum power tracking circuit 30 to supply power to the load.

[0116] Further, if the control module 220 compares and finds that the demand power is greater than the power reference value, the control module 220 generates a supplementary power supply control signal to the energy storage device 60 according to a power difference between the demand power and the power reference value, so as to control the energy storage device 60 to output an electrical signal with the power difference, and make the main photovoltaic panel 10 and the energy storage device 60 jointly supply power to the load.

[0117] It can be understood that, in at least one embodiment, the maximum power point tracking control device 200 can be built into the controller 50 in the photovoltaic system 100.

[0118] The application further provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the maximum power point tracking method as described above.

[0119] The processor can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor and the like. The processor is an operation core and control center of the photovoltaic system 100, and connects various parts of the photovoltaic system 100 through various interfaces and lines, and obtains output power and other parameters of the reference photovoltaic panel 20 and the main photovoltaic panel 10 in the photovoltaic system 100.

[0120] The processor obtains the output power and other parameters of the reference photovoltaic panel 20 and the main photovoltaic panel 10 in the photovoltaic system 100. The processor obtains the above-mentioned parameters to implement the steps in the above-mentioned maximum power point tracking method embodiments, for example Figure 5 .

[0121] The computer program stored in the computer readable storage medium can implement the steps of the above-mentioned various method embodiments when executed by the processor. The computer program includes computer program code, which can be in the form of source code, object code, executable files or some intermediate forms, etc. The computer readable medium can include any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM) and the like.

[0122] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A maximum power point tracking method, characterized by, The application is applied to a photovoltaic system, the photovoltaic system comprises a main photovoltaic panel, a reference photovoltaic panel, a maximum power tracking circuit and an output power detection circuit; the maximum power tracking circuit is connected with the main photovoltaic panel; the output power detection circuit is connected with the reference photovoltaic panel; The reference photovoltaic panel and the main photovoltaic panel have the same configuration parameters and are in the same environment; The maximum power point tracking method comprises: The maximum output power of the reference photovoltaic panel is acquired through the output power detection circuit; When the maximum output power of the reference photovoltaic panel is greater than or equal to a first preset threshold value, a first control signal is sent to the maximum power tracking circuit, and the first control signal is used for controlling the maximum power tracking circuit to perform maximum power point tracking on the output power of the main photovoltaic panel.

2. The maximum power point tracking method according to claim 1, wherein, The method further comprises: According to the maximum output power of the reference photovoltaic panel, a power reference value of the maximum output power of the main photovoltaic panel is acquired; An actual maximum output power value of the main photovoltaic panel obtained after the maximum power tracking circuit performs maximum power point tracking on the output power of the main photovoltaic panel is acquired; If a power difference value between the power reference value and the actual maximum output power value is greater than or equal to a preset difference threshold value, it is determined that the photovoltaic system has a fault.

3. The maximum power point tracking method of claim 2, wherein, According to the maximum output power of the reference photovoltaic panel, a power reference value of the maximum output power of the main photovoltaic panel is acquired, comprising: The maximum output power of the reference photovoltaic panel is multiplied by a preset multiple to obtain the power reference value of the maximum output power of the main photovoltaic panel; The preset multiple is in a positive correlation relationship with a ratio between a rated output power of the main photovoltaic panel and a rated output power of the reference photovoltaic panel.

4. The maximum power point tracking method of claim 3, wherein, The photovoltaic system further comprises an energy storage device connected with the maximum power tracking circuit; after the step of sending the first control signal to the maximum power tracking circuit, the maximum power point tracking method further comprises: A minimum charging power of the energy storage device is acquired; If the minimum charging power is less than or equal to the power reference value, a charging control signal is output, and the charging control signal is used for controlling the maximum power tracking circuit to charge the energy storage device.

5. The maximum power point tracking method of claim 3, wherein, The photovoltaic system further comprises an inverter circuit; an input end of the inverter circuit is used for being connected with an output end of the maximum power tracking circuit; an output end of the inverter circuit is used for connecting a load; after the step of sending the first control signal to the maximum power tracking circuit, the method further comprises: A demand power of the load is acquired; If the demand power is less than or equal to the power reference value, a power supply control signal is output, and the power supply control signal is used for controlling the inverter circuit to supply power to the load after converting an output voltage of the maximum power tracking circuit.

6. The maximum power point tracking method of claim 5, wherein, The method further comprises: If the demand power is greater than the power reference value, a supplementary power supply control signal is generated to the energy storage device according to a power difference value between the demand power and the power reference value; the supplementary power supply control signal is used for controlling the energy storage device to output an electric signal with the power difference value.

7. A photovoltaic system characterized by, The photovoltaic system comprises a main photovoltaic panel, a reference photovoltaic panel, a maximum power tracking circuit and an output power detection circuit, and a controller; The maximum power tracking circuit is connected with the main photovoltaic panel, and the output power detection circuit is connected with the reference photovoltaic panel; the reference photovoltaic panel and the main photovoltaic panel have the same configuration parameters and are in the same environment; The controller is used to execute the maximum power point tracking method as claimed in any one of claims 1-6.

8. The photovoltaic system of claim 7, wherein, The output power detection circuit comprises a voltage dividing unit and a sampling unit; the voltage dividing unit comprises a plurality of voltage dividing branches connected with the reference photovoltaic panel; each voltage dividing branch comprises a voltage dividing resistor and a switch; the voltage dividing resistors of the voltage dividing branches are different; and the sampling unit is used to collect the output voltage of the reference photovoltaic panel. The controller is further used to sequentially turn on each voltage dividing branch to obtain the output power in different states through the sampling unit and determine the maximum output power of the reference photovoltaic panel.

9. The photovoltaic system of claim 8, wherein, The sampling unit comprises a first sampling resistor, a second sampling resistor, a third sampling resistor and a filter capacitor; one end of the first sampling resistor is connected with the reference photovoltaic panel, the other end of the first sampling resistor is connected with one end of the second sampling resistor, the other end of the second sampling resistor is grounded, one end of the third sampling resistor is connected between the first sampling resistor and the second sampling resistor, the other end of the third sampling resistor is connected with the controller, one end of the filter capacitor is connected with the other end of the third sampling resistor, and the other end of the filter capacitor is grounded. The controller is used to: obtain the node voltage of a connection node between the third sampling resistor and the filter capacitor, and calculate the output voltage according to the proportional relationship of the node voltage and the resistance values of the first sampling resistor and the second sampling resistor; calculate the output power according to the output voltage and the resistance value of the voltage dividing resistor of the turned-on voltage dividing branch.

10. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by a processor to realize the maximum power point tracking method as claimed in any one of claims 1-6.

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