A multi-peak scanning system and method based on MPPT tracking of photovoltaic inverters

Abstract

This application discloses a multi-peak scanning system based on MPPT tracking of a photovoltaic inverter, including an MPPT module, a detection module, and a controller. The detection module detects the current maximum power output curve of the photovoltaic array and compares it with a given maximum output power. The controller controls the MPPT module to perform maximum power tracking based on the comparison result. A multi-peak scanning method based on MPPT tracking of a photovoltaic inverter is also disclosed, comprising the following steps: assigning an initial given maximum output power P... 给定 ; Obtain the maximum power P of the current output curve of the photovoltaic array. 当前 If P 当前 ≥P 给定 Then the photovoltaic inverter uses P 当前 MPPT tracking is performed for the maximum output power; otherwise, the given maximum output power is decreased by a set step size ΔP and the above steps are repeated. The beneficial effect of this application is that by assigning an initial given maximum output power, the MPPT module can avoid getting trapped in local optima during maximum power tracking.

Description

Technical Field

[0001] This application relates to the field of photovoltaic power generation technology, and in particular to a multi-peak scanning system and method based on MPPT tracking of a photovoltaic inverter. Background Technology

[0002] With the advent of Industry 4.0, electricity has become an indispensable part of production and daily life. As my country has built the world's largest clean power generation system and its energy structure continues to optimize, the development of photovoltaic power generation systems is progressing rapidly. Among these advancements, the utilization rate of photovoltaic modules or cells is paramount to power generation efficiency.

[0003] In real-world production and daily life, photovoltaic arrays do not always operate under ideal unshaded conditions. When a photovoltaic array is shaded, such as by natural or artificial conditions like buildings, clouds, or tree shade, the light intensity received by the shaded and unshaded parts is inconsistent, resulting in multiple local peaks in its PV characteristic curve. Traditional technical solutions struggle to find the optimal value under multi-peak curves. Summary of the Invention

[0004] One of the objectives of this application is to provide a multi-peak scanning system that can quickly and accurately achieve inverter MPPT tracking.

[0005] Another objective of this application is to provide a multi-peak scanning method that can quickly and accurately achieve inverter MPPT tracking.

[0006] To achieve at least one of the above objectives, the technical solution adopted in this application is as follows: a multi-peak scanning system based on MPPT tracking of a photovoltaic inverter, comprising an MPPT module, a detection module, and a controller electrically connected to each other; the detection module is given an initial maximum output power, and the detection module is adapted to detect the current maximum output power of the photovoltaic array and compare it with the given maximum output power; the controller is adapted to send a control signal for maximum power tracking to the MPPT module according to the comparison result of the detection module.

[0007] Preferably, the detection module includes a power loop and a detection loop that are electrically connected to each other; the power loop is given an initial maximum output power, and the detection loop is adapted to detect the maximum output power of the photovoltaic array at present.

[0008] Preferably, the detection loop includes a voltage loop and a current loop. The voltage loop is used to scan the voltage value of the photovoltaic curve currently output by the photovoltaic array, and the current loop is used to scan the current value of the photovoltaic curve currently output by the photovoltaic array. Thus, the maximum power of the photovoltaic array curve is obtained through the scanned voltage and current values.

[0009] Preferably, the MPPT module, the detection module, and the controller are electrically connected in sequence to form a control loop; wherein the power loop, the voltage loop, and the current loop are connected in sequence to form an outer power loop, a middle voltage loop, and an inner current loop.

[0010] Preferably, during the MPPT tracking process, the MPPT module is adapted to record the maximum output power of the photovoltaic inverter; and the MPPT module is adapted to assign an initial maximum output power to the power loop based on the historical records.

[0011] A multi-peak scanning method based on MPPT tracking of a photovoltaic inverter includes the following steps:

[0012] S100: Set the initial maximum output power P 给定 ;

[0013] S200: Scan the current output curve of the photovoltaic array to obtain the maximum power P of the current output curve of the photovoltaic array. 当前 ;

[0014] S300: If the maximum power P of the curve 当前 Greater than or equal to the given maximum output power P 给定 If the maximum power of the curve is reached, the parameter signal corresponding to the maximum power of the curve will be sent to the photovoltaic inverter for MPPT tracking; otherwise, proceed to step S400.

[0015] S400: Gradually decrease the given maximum output power value according to the set step size ΔP and repeat the above steps S200 and S300.

[0016] Preferably, the step size ΔP is the given maximum output power P. 给定 1%-10%.

[0017] Preferably, the step size ΔP is a constant; that is, the step size ΔP is the initial given maximum output power P. 给定 1%-10%.

[0018] Preferably, when at least two steps S400 are performed, the step size ΔP is a changed value; that is, the step size ΔP is the given maximum output power P after the previous step size reduction. 给定 1%-10%.

[0019] Preferably, when scanning the output voltage of the photovoltaic array in step S200, the scan is performed from the open-circuit voltage end of the output curve to the zero voltage end.

[0020] Compared with the prior art, the beneficial effects of this application are as follows:

[0021] (1) The control structure of the multi-peak scanning system of this application is simple and easy to understand. By assigning an initial maximum output power to the detection module and comparing it with the maximum power of the currently detected curve, the amount of calculation can be reduced, thereby quickly realizing MPPT tracking of the maximum power point of the photovoltaic inverter.

[0022] (2) In the process of MPPT maximum power point tracking, the multi-peak scanning method of this application can avoid getting trapped in local optima by using the given maximum output power as a benchmark, thereby effectively improving the accuracy of MPPT tracking. Attached Figure Description

[0023] Figure 1 This is the photovoltaic curve output after the photovoltaic array is partially shaded.

[0024] Figure 2 This is a schematic diagram of the overall control loop structure of the present invention.

[0025] Figure 3 This is a schematic diagram of the overall process of the present invention.

[0026] In the diagram: Photovoltaic array 100, MPPT module 200, power loop 300, voltage loop 400, current loop 500, controller 600. Detailed Implementation

[0027] The present application will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0028] In the description of this application, it should be noted that the directional terms such as "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this application.

[0029] It should be noted that the terms "first," "second," etc., in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0030] One aspect of this application provides a multi-peak scanning system based on MPPT tracking of a photovoltaic inverter, such as... Figure 2As shown, one preferred embodiment includes an MPPT module 200, a detection module, and a controller 600 electrically connected to each other. The detection module is given an initial maximum output power, and it can also detect the current maximum output power curve of the photovoltaic array 100 and compare it with the given maximum output power. The controller 600 can send a control signal for maximum power point tracking to the MPPT module 200 based on the comparison result of the detection module, thereby enabling the MPPT module 200 to control the photovoltaic inverter to output maximum power.

[0031] Understandably, the comparison between the given maximum output power and the maximum power on the curve can be divided into two cases. The first case is: if the given maximum output power is greater than the maximum power on the curve, it means that the current maximum output power of the photovoltaic array 100 is lower than the given maximum output power. The second case is: if the given maximum output power is less than or equal to the maximum power on the curve, it means that the current maximum output power of the photovoltaic array 100 can be used as the maximum output power of the photovoltaic inverter.

[0032] For the first case mentioned above, the given maximum output power value can be further reduced and compared with the maximum output power curve of the photovoltaic array. If the first case still applies, the given maximum output power value can be further reduced until the second case is met.

[0033] In the second scenario described above, the MPPT module 200 can be directly controlled to track the maximum power curve of the photovoltaic array 100, thereby controlling the photovoltaic inverter to output maximum power.

[0034] As can be seen from the above, when performing multi-peak scanning based on MPPT tracking of a photovoltaic inverter, this application can use the given maximum output power as a benchmark; therefore, when detecting the output curve of the photovoltaic array 100, it can always compare it with the given maximum output power. By gradually decreasing the value of the given maximum output power until the maximum power value of the current output curve of the photovoltaic array 100 is slightly greater than or equal to the given maximum output power value, the maximum output power of the photovoltaic inverter corresponding to the photovoltaic array 100 at this time can be obtained. Thus, the MPPT module 200 can perform corresponding maximum power tracking based on the comparison result.

[0035] To facilitate understanding, the explanation can be based on existing technologies.

[0036] Existing technology directly scans the photovoltaic curve from the open-circuit voltage end to the zero voltage end through the detection module. During the scanning process, if the power value corresponding to the current photovoltaic curve is less than the power value corresponding to the previous step length, the scanning stops, and the power point corresponding to the previous step length can be determined as the maximum power point.

[0037] Specifically Figure 1 For example, based on the above process, existing technology can determine point B as the maximum power point of the current photovoltaic curve of photovoltaic array 100. And... Figure 1 The maximum power point corresponding to the photovoltaic curve of the photovoltaic array 100 shown is point A. This means that existing technology is only suitable for scanning single-peak photovoltaic curves and not for scanning multi-peak photovoltaic curves. When scanning multi-peak photovoltaic curves, it is easy to get trapped in local optima.

[0038] In this application, by assigning an initial maximum output power, it is unnecessary to compare the power corresponding to different time points of the photovoltaic curve itself; it is only necessary to ensure that after completing the entire scan of the photovoltaic curve, the overall maximum power point of the photovoltaic curve is greater than or equal to the given maximum output power value. This effectively avoids getting trapped in local optima when performing multi-peak photovoltaic curve scanning.

[0039] In this embodiment, as Figure 2 As shown, the detection module includes a power loop 300 and a detection loop that are electrically connected to each other. The power loop 300 can be assigned an initial maximum output power, and the detection loop can detect the current maximum output power curve of the photovoltaic array 100 in real time and compare the detected maximum output power curve with the given maximum output power of the power loop 300.

[0040] Specifically, such as Figure 2 As shown, the detection loop includes a voltage loop 400 and a current loop 500. The voltage loop 400 is used to scan the voltage value of the photovoltaic curve currently output by the photovoltaic array 100, and the current loop 500 is used to scan the current value of the photovoltaic curve currently output by the photovoltaic array 100. Thus, the maximum power of the current curve can be obtained through the voltage and current values ​​currently scanned by the photovoltaic array 100.

[0041] In this embodiment, as Figure 2 As shown, the MPPT module 200, power loop 300, voltage loop 400, current loop 500, and controller 600 are sequentially electrically connected to form a control loop. Specifically, the power loop 300, voltage loop 400, and current loop 500 are connected sequentially to form an outer power loop, a middle voltage loop, and an inner current loop. Thus, when the control loop is operating, the MPPT module 200 can assign a value to the power loop 300, specifically assigning it an initial maximum output power and sending it to the controller 600; simultaneously, the voltage loop 400 and current loop 500 scan the current photovoltaic curve of the photovoltaic array 100 to obtain the current maximum power of the photovoltaic array 100 and send it to the controller 600; then, the controller 600 compares the given maximum output power with the maximum power of the curve, and based on the comparison result, sends a control signal to the MPPT module 200 to control the photovoltaic inverter to output maximum power.

[0042] It is understandable that the given maximum output power value assigned to the power loop 300 can also be manually assigned to the power loop 300. Of course, in order to ensure the accuracy of the tracking results of the MPPT module 200 of this application, the given maximum power value assigned to the power loop 300 initially must be at least equal to the maximum power value that the photovoltaic array can output under no partial shading.

[0043] To improve the operating speed of the multi-peak scanning system of this application, it is preferable to use the MPPT module 200 to assign values ​​to the power loop 300. During MPPT tracking, the MPPT module 200 can record the historical maximum output power of the photovoltaic inverter. Therefore, when performing multi-peak scanning, the MPPT module 200 can assign an initial maximum output power to the power loop 300 based on the historical maximum value.

[0044] Another aspect of this application provides a multi-peak scanning method based on MPPT tracking of a photovoltaic inverter, such as... Figure 3 As shown, one preferred embodiment includes the following steps:

[0045] S100: Can assign an initial maximum output power P to the power loop 300. 给定 .

[0046] S200: The photovoltaic curve currently output by the photovoltaic array 100 is scanned through the voltage loop 400 and the current loop 500 to obtain the maximum power P corresponding to the photovoltaic curve currently output by the photovoltaic array 100. 当前 .

[0047] It is understandable that when scanning the output voltage of the photovoltaic array 100 in step S200, the voltage loop 400 can scan from the open-circuit voltage end of the photovoltaic curve to the zero voltage end.

[0048] S300: Given the maximum output power P 给定 With curve maximum power P 当前 Compare the curves; if the maximum power P of the curve is... 当前 Greater than or equal to the given maximum output power P 给定 This indicates that the maximum power P corresponding to the photovoltaic curve currently output by photovoltaic array 100 is... 当前 This is the maximum power output of the photovoltaic inverter. The controller 600 then displays the maximum power P curve. 当前 The corresponding parameter signal is sent to the MPPT module 200 so that the MPPT module 200 controls the photovoltaic inverter to perform MPPT tracking and output maximum power; otherwise, proceed to step S400.

[0049] S400: Gradually decrease the given maximum output power P according to the set step size ΔP. 给定 The value is then repeated using steps S200 and S300.

[0050] In this embodiment, the step size ΔP is the given maximum output power P. 给定 1%-10%.

[0051] Specifically, the step size ΔP can be a constant; that is, the step size ΔP is the initial given maximum output power P. 给定 1%-10%.

[0052] It is understandable that, depending on the value of the step size ΔP, the maximum output power P given in step S400 will vary. 给定 The methods for gradually decreasing the step size are different.

[0053] The following explanation uses specific parameters. Assume the initial maximum output power is P; the maximum peak value of the photovoltaic curve output by photovoltaic array 100 is 0.85P. If the step size ΔP is small, for example, ΔP = 0.01P, then to achieve the reduced maximum output power P... 给定 = Maximum power P of the curve 当前 If step S400 is repeated 14 times, then the number of loops in this application is relatively large, which in turn affects the multi-peak scanning efficiency of this application.

[0054] To improve the multi-peak scanning efficiency of this application, the step size ΔP can be set to include a first step size ΔP1 and a second step size ΔP2; ΔP1 = kΔP2, k > 1.

[0055] Then, in step S400, the maximum output power P is given. 给定 The process of gradually decreasing the step size includes the following steps:

[0056] S410: Given the maximum output power P 给定 Reduce the first step length ΔP1; and repeat steps S200 and S300 once; determine the current maximum power P of the curve. 当前 Is it less than the current given maximum output power P? 给定 ;

[0057] S420: If the current curve has a maximum power P 当前 Less than the current given maximum output power P 给定 Then repeat step S410 until the current curve reaches its maximum power P. 当前 Greater than or equal to the current given maximum output power P 给定 Then proceed to step S430;

[0058] S430: The given maximum output power P obtained in step S420 is then used to... 给定 Add a second step size ΔP2; and loop through steps S200 and S300 once accordingly; determine the current maximum power P of the curve. 当前 Is it greater than the given maximum output power P?

[0059] S440: If the current curve has a maximum power P 当前 Greater than the current given maximum output power P 给定 Then repeat step S430 until the current curve reaches its maximum power P. 当前 Less than the current given maximum output power P 给定 Then output the maximum power P of the curve corresponding to the previous cycle. 当前 This represents the maximum output power point of the photovoltaic inverter.

[0060] To facilitate understanding, we can continue with the explanation using parameters. Assume the initial maximum output power is P; the maximum peak value of the photovoltaic curve output by photovoltaic array 100 is 0.85P. The first step length ΔP1 is 0.1P, and k is 10, then ΔP2 = 0.01P.

[0061] Based on steps S410 to S440 above, if we want to achieve the reduced given maximum output power P 给定 = Maximum power P of the curve 当前 Therefore, step S410 needs to be cycled twice, and then step S440 needs to be cycled six times, which means a total of only eight cycles are required; compared with the aforementioned 14 cycles, this can effectively improve the multi-peak scanning efficiency of this application.

[0062] It is also understandable that the step size ΔP can be a variable value, but step S400 needs to be executed at least twice. That is, the current step size ΔP is the given maximum output power P after the previous step size reduction. 给定 1%-10%.

[0063] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. A multi-peak scanning method based on photovoltaic inverter MPPT tracking, characterized in that, The MPPT module, the detection module and the controller are electrically connected with each other; the detection module is given an initial given maximum output power, and the detection module is adapted to detect the curve maximum power of the current output of the photovoltaic array and compare it with the given maximum output power; the controller is adapted to send a control signal for maximum power tracking to the MPPT module according to the comparison result of the detection module; The detection module comprises a power ring and a detection ring which are electrically connected with each other; the power ring is given an initial given maximum output power, and the detection ring is adapted to detect the curve maximum power of the current output of the photovoltaic array; The detection ring comprises a voltage ring and a current ring, the voltage ring is used for scanning the voltage value of the photovoltaic curve of the current output of the photovoltaic array, and the current ring is used for scanning the current value of the photovoltaic curve of the current output of the photovoltaic array; and then the current curve maximum power of the photovoltaic array is obtained through the scanned voltage value and current value; The specific scanning process is as follows: S100: Set the initial given maximum output power P 给定 ; S200: Obtain the curve maximum power P of the current output of the photovoltaic array 当前 ; S300: If P 当前 ≥ P 给定 , the photovoltaic inverter performs MPPT tracking with P 当前 as the maximum output power. Otherwise, step S400 is performed; S4 00: in accordance with the set step Pdecreases the value of the given maximum output power step by step and repeats the steps S200 and S300 described above.

2. The photovoltaic inverter MPPT tracking based multi-peak scanning method of claim 1, wherein: The MPPT module, the detection module and the controller are electrically connected with each other to form a control loop; wherein the power ring, the voltage ring and the current ring are connected in sequence to form a power outer ring, a voltage middle ring and a current inner ring.

3. The multi-peak scanning method based on photovoltaic inverter MPPT tracking according to claim 1 or 2, characterized in that: In the process of performing MPPT tracking, the MPPT module is adapted to record the maximum output power of the photovoltaic inverter; and then the MPPT module is adapted to give the power ring an initial given maximum output power according to the historical record.

4. The photovoltaic inverter MPPT tracking based multi-peak scanning method of claim 1, wherein: Set step size P is the given maximum output power P 给定 1%-10%.

5. The photovoltaic inverter MPPT tracking based multi-peak scanning method of claim 4, wherein: Step size P is a constant; i.e. step size P is the initial given maximum output power P 给定 1% - 10%.

6. The photovoltaic inverter MPPT tracking based multi-peak scanning method of claim 4, wherein: When at least two steps S400 are performed, the step size P is the change value; i.e. the step size P is the given maximum output power P after the last step size reduction 给定 1% - 10%.

7. The photovoltaic inverter MPPT tracking based multi-peak scanning method of claim 1, wherein: In step S200, the scanning of the output voltage of the photovoltaic array is performed from the open circuit voltage end to the zero voltage end of the output curve.

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