Maximum power point tracking method and apparatus based on photovoltaic array output characteristics

Abstract

The present application discloses a maximum power point tracking method and apparatus based on photovoltaic array output characteristics. A photovoltaic array comprises photovoltaic modules. In the present application, by means of the feature that all local optimal points of an output power characteristic curve of the photovoltaic array are located near the open-circuit voltage of an integer multiple of photovoltaic modules, i.e., the principle that the local optimal points are uniformly distributed by taking the open-circuit voltage of the photovoltaic modules as a base amount, a global optimal point, i.e., a first maximum power point, of the output power characteristic curve can be quickly located only by searching for the output power characteristic curve by taking the open-circuit voltage of the photovoltaic modules as a search step size. Compared with a conventional tracking method, a complete output power characteristic curve of the photovoltaic array does not need to be scanned, greatly increasing the optimization speed; additionally, accurate search is performed by using a particle swarm algorithm to obtain an actual global optimal point, i.e., a target maximum power point, of the output power characteristic curve, thereby preventing the algorithm from falling into local optimum.

Description

A maximum power point tracking method and device based on photovoltaic array output characteristics Technical Field

[0001] The present application relates to the technical field of photovoltaic arrays, and in particular to a maximum power point tracking method and device based on the output characteristics of a photovoltaic array. Background Art

[0002] Photovoltaic arrays, as the energy conversion unit of photovoltaic power generation systems, are a research hotspot in the field of photovoltaic power generation technology. The PV output of a PV array exhibits complex nonlinear characteristics and is affected by external environmental factors such as temperature and light intensity. When the surface of a PV array is uniformly illuminated, its PV output exhibits a single peak, and the PV curve has a global maximum power point. However, when the surface of a PV array is unevenly illuminated, such as when the array is obscured by objects such as fallen leaves or dark clouds, resulting in shadows on the surface of the PV array, the PV output exhibits a multi-peak characteristic, and the PV curve has several local maximum power points. In practical applications, PV power generation systems require control methods to ensure that the PV array consistently outputs maximum power and improve system efficiency. This control process is known as maximum power point tracking (MPPT).

[0003] Existing maximum power point tracking (MPPT) methods mostly utilize complex mathematical methods or incorporate deep learning, making them difficult to implement and complex, making them difficult to apply in practice. Furthermore, most methods require scanning the entire PU characteristic curve, resulting in a slow search speed.

[0004] Summary of the Invention

[0005] In view of this, the embodiments of the present application provide a maximum power point tracking method and device based on the output characteristics of a photovoltaic array to solve the technical problems in the prior art that maximum power point tracking is difficult to implement, the implementation process is complex, it is difficult to apply in practice, and the search speed is slow.

[0006] The technical solutions proposed in this application are as follows:

[0007] In a first aspect, an embodiment of the present application provides a maximum power point tracking method based on the output characteristics of a photovoltaic array, wherein the photovoltaic array includes a photovoltaic module; the maximum power point tracking method based on the output characteristics of the photovoltaic array includes: obtaining the output voltage, output current and first open-circuit voltage of the photovoltaic array and the photovoltaic module; determining the volt-ampere characteristic curve and the output power characteristic curve of the photovoltaic array based on the output voltage and the output current; using the first open-circuit voltage as the search step, utilizing the distribution principle that the local optimal points of the volt-ampere characteristic curve and the output power characteristic curve are uniformly distributed with the first open-circuit voltage as the basis, searching in the output power characteristic curve to obtain a first maximum power point; based on the first maximum power point, obtaining the target maximum power point of the photovoltaic array through particle swarm algorithm processing.

[0008] In combination with the first aspect, in a possible implementation of the first aspect, obtaining the first open-circuit voltage of the photovoltaic component includes: obtaining the second open-circuit voltage of the photovoltaic array and the number of series-connected batteries of the photovoltaic array; and determining the first open-circuit voltage based on the second open-circuit voltage and the number of series-connected batteries.

[0009] In combination with the first aspect, in another possible implementation of the first aspect, the first open circuit voltage is used as a search step length, and a distribution principle is utilized in which the local optimal points of the volt-ampere characteristic curve and the output power characteristic curve are uniformly distributed with the first open circuit voltage as the base quantity, and a search is performed in the output power characteristic curve to obtain a first maximum power point, including: determining an initial point voltage based on the first open circuit voltage; determining a maximum search voltage based on the initial point voltage, the first open circuit voltage, and the number of batteries connected in series; determining a search range based on the initial point voltage and the maximum search voltage; and within the search range, searching in the output power characteristic curve based on the volt-ampere characteristic curve with the first open circuit voltage as the search step length to obtain the first maximum power point.

[0010] In combination with the first aspect, in another possible implementation of the first aspect, within the search range, based on the volt-ampere characteristic curve, searching the output power characteristic curve with the first open-circuit voltage as the search step to obtain the first maximum power point includes: obtaining a first voltage of the photovoltaic array; determining a first current of the photovoltaic array in the volt-ampere characteristic curve based on the first voltage; determining a first power of the photovoltaic array based on the first voltage and the first current; updating the first voltage based on the search step and obtaining an updated second voltage and second current of the photovoltaic array; determining a second power of the photovoltaic array based on the second voltage and the second current; comparing the second power with the first power; when the second power is greater than the first power, updating the first power using the second power and updating the first voltage using the second voltage, until the second voltage iterates to the maximum search voltage and stops iterating to obtain a target voltage; and determining the first maximum power point in the output power characteristic curve based on the target voltage.

[0011] In combination with the first aspect, in another possible implementation of the first aspect, after comparing the second power with the first power, the method further includes: when the second power is less than the first power, determining the first maximum power of the photovoltaic array based on the volt-ampere characteristic curve, the maximum search voltage and the second current; comparing the first maximum power with the first power; when the first maximum power is greater than the first power, repeating the steps of updating the first voltage based on the search step and obtaining the updated second voltage and second current of the photovoltaic array to determining the first maximum power point in the output power characteristic curve based on the target voltage; when the first maximum power is less than and equal to the first power, determining whether the second power is equal to the first power; when the second power is equal to the first power, using the power point corresponding to the second power as the first maximum power point.

[0012] In combination with the first aspect, in another possible implementation of the first aspect, based on the first maximum power point, a target maximum power point of the photovoltaic array is obtained through particle swarm algorithm processing, including: based on the first maximum power point, determining a third voltage of the photovoltaic array in the output power characteristic curve; determining an initialization voltage of each particle based on the third voltage; calculating a first search power of each particle based on the initialization voltage of each particle; determining a second maximum power and a third maximum power of the photovoltaic array based on each first search power; updating the position and velocity of each particle, and determining whether the second maximum power is equal to the third maximum power; when the second maximum power is equal to the third maximum power, obtaining a fourth voltage and a third current of the photovoltaic array; determining a third power of the photovoltaic array based on the fourth voltage and the third current; determining whether the third power meets a preset power range; when the third power meets the preset power range, using the power point corresponding to the second maximum power as the target maximum power point.

[0013] In combination with the first aspect, in another possible implementation of the first aspect, after updating the position and velocity of each particle and determining whether the second maximum power is equal to the third maximum power, the method further includes: when the second maximum power is not equal to the third maximum power, based on each updated particle, repeating the step of calculating the first search power of each particle based on the initialization voltage of each particle, until when the third power satisfies the preset power range, the power point corresponding to the second maximum power is used as the target maximum power point.

[0014] In a second aspect, an embodiment of the present application provides a maximum power point tracking device based on the output characteristics of a photovoltaic array, wherein the photovoltaic array includes a photovoltaic module; the maximum power point tracking device based on the output characteristics of the photovoltaic array includes: an acquisition module for acquiring the output voltage, output current and first open-circuit voltage of the photovoltaic array and the photovoltaic module; a determination module for determining the volt-ampere characteristic curve and the output power characteristic curve of the photovoltaic array based on the output voltage and the output current; a search module for using the first open-circuit voltage as a search step, utilizing the distribution principle that the local optimal points of the volt-ampere characteristic curve and the output power characteristic curve are uniformly distributed with the first open-circuit voltage as a basis, searching in the output power characteristic curve to obtain a first maximum power point; a processing module for obtaining the target maximum power point of the photovoltaic array based on the first maximum power point through particle swarm algorithm processing.

[0015] In a third aspect, an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and the computer program is used to enable the computer to execute the maximum power point tracking method based on the output characteristics of the photovoltaic array as described in the first aspect and any one of the first aspects of the embodiment of the present application.

[0016] In a fourth aspect, an embodiment of the present application provides an electronic device, comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing a computer program, and the processor executing the computer program to execute the maximum power point tracking method based on the output characteristics of the photovoltaic array as described in the first aspect and any one of the first aspects of the embodiment of the present application.

[0017] The technical solution provided by this application has the following effects:

[0018] The maximum power point tracking method based on the output characteristics of a photovoltaic array, provided in an embodiment of the present application, utilizes the characteristic that each local optimum of the photovoltaic array's output power characteristic curve is located near an integer multiple of the photovoltaic module's open-circuit voltage. This principle states that each local optimum is uniformly distributed based on the photovoltaic module's open-circuit voltage. By simply searching the output power characteristic curve using the photovoltaic module's open-circuit voltage as the search step, the global optimum of the output power characteristic curve, i.e., the first maximum power point, can be quickly located. Compared with traditional tracking methods, this method eliminates the need to scan the entire photovoltaic array's output power characteristic curve, significantly improving the search speed. Furthermore, a particle swarm algorithm is used for precise search to obtain the actual global optimum of the output power characteristic curve, i.e., the target maximum power point, preventing the algorithm from falling into a local optimum. Furthermore, the search process utilizes the inherent characteristics of the photovoltaic array during operation, resulting in universal applicability and high reliability, which can be further applied to the promotion and use of photovoltaic power stations. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] FIG1 is a flow chart of a maximum power point tracking method based on photovoltaic array output characteristics according to an embodiment of the present application;

[0021] FIG2 is a flow chart of step 103 according to an embodiment of the present application;

[0022] FIG3 is a flow chart of step 104 according to an embodiment of the present application;

[0023] FIG4 is another flow chart of a maximum power point tracking method based on photovoltaic array output characteristics according to an embodiment of the present application;

[0024] FIG5 is an equivalent circuit diagram of a 4×2 photovoltaic array provided according to an embodiment of the present application;

[0025] FIG6 is a graph showing output characteristics of a 4×2 photovoltaic array according to an embodiment of the present application;

[0026] FIG7 is a structural block diagram of a maximum power point tracking method and apparatus based on photovoltaic array output characteristics according to an embodiment of the present application;

[0027] FIG8 is a schematic diagram of the structure of a computer-readable storage medium provided according to an embodiment of the present application;

[0028] FIG9 is a schematic structural diagram of an electronic device provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0029] To make the purpose, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of this application.

[0030] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in a sequence other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0031] The present invention provides a maximum power point tracking method based on the output characteristics of a photovoltaic array. As shown in FIG1 , the method includes the following steps:

[0032] Step 101: Obtain the output voltage, output current of the photovoltaic array and the first open-circuit voltage of the photovoltaic component.

[0033] The photovoltaic array includes photovoltaic modules.

[0034] Specifically, the output voltage, output current and first open circuit voltage V of the photovoltaic array are collected. OC,M .

[0035] Step 102: Determine a volt-ampere characteristic curve and an output power characteristic curve of the photovoltaic array based on the output voltage and the output current.

[0036] Specifically, the volt-ampere characteristic curve (IU characteristic curve) and the output power characteristic curve (PU characteristic curve) of the photovoltaic array can be obtained according to the collected output voltage and output current of the photovoltaic array.

[0037] Step 103: Using the first open circuit voltage as a search step, utilizing the principle that local optimal points of the volt-ampere characteristic curve and the output power characteristic curve are uniformly distributed based on the first open circuit voltage, searching in the output power characteristic curve to obtain a first maximum power point.

[0038] Specifically, using the IU characteristic curve, based on the local optimal point of the photovoltaic array PU characteristic curve and the first open-circuit voltage V OC,M The principle of uniform distribution of base amount, based on V OC,M The global optimal point of the PU characteristic curve, ie, the first maximum power point, is searched for a search step size ΔV.

[0039] Step 104: Based on the first maximum power point, a target maximum power point of the photovoltaic array is obtained by performing particle swarm optimization processing.

[0040] Among them, the particle swarm algorithm described in the embodiment of the present application has N particles, the dimension is d, the position vector is S, and the velocity vector is V. Then the d-dimensional particle group position matrix S d The following relationship (1) shows: S d =(S 1d ,S 2d ,S 3d ,…,S Nd ) (1)

[0041] Where: S Nd Represents the Nth d-dimensional particle position matrix.

[0042] d-dimensional particle group velocity matrix V d The following relationship (2) shows: V d =(V 1d ,V 2d ,V 3d ,…,V Nd ) (2)

[0043] Where: VNd Represents the Nth d-dimensional particle velocity matrix.

[0044] The particle velocity vector iteration formula is shown in the following relationship (3):

[0045] Where: V id represents the velocity vector of the particle; ω represents the weight of the last iteration velocity of the individual particle swarm; c1 and c2 represent learning factors, which are used to adjust the tendency weights toward the individual historical optimum and the global optimum; r1 and r2 represent random numbers, which are used to adjust the step size of the learning factor; j represents the number of iterations; P best,id is the historical optimal value of the particle position; G best,id is the global optimal value of the particle position; S id represents the position vector of the particle. The specific position vector iteration formula is shown in the following relationship (4):

[0046] In the embodiment of the present application, N is the number of initial search points on the PU characteristic curve; P best,id is the local maximum power found at each search point; G best,id is the global maximum power found at each search point.

[0047] Specifically, the particle swarm algorithm is used to accurately search the actual maximum power point of the PU characteristic curve near the first maximum power point, that is, the target maximum power point P GM .

[0048] Through the particle swarm algorithm processing, the maximum power point searched is avoided from being the local optimal power point, and the tracking accuracy of the maximum power point is improved.

[0049] The maximum power point tracking method based on the output characteristics of a photovoltaic array, provided in an embodiment of the present application, utilizes the characteristic that each local optimum of the photovoltaic array's output power characteristic curve is located near an integer multiple of the photovoltaic module's open-circuit voltage. This principle states that each local optimum is uniformly distributed based on the photovoltaic module's open-circuit voltage. By simply searching the output power characteristic curve using the photovoltaic module's open-circuit voltage as the search step, the global optimum of the output power characteristic curve, i.e., the first maximum power point, can be quickly located. Compared with traditional tracking methods, this method eliminates the need to scan the entire photovoltaic array's output power characteristic curve, significantly improving the search speed. Furthermore, a particle swarm algorithm is used for precise search to obtain the actual global optimum of the output power characteristic curve, i.e., the target maximum power point, preventing the algorithm from falling into a local optimum. Furthermore, the search process utilizes the inherent characteristics of the photovoltaic array during operation, resulting in universal applicability and high reliability, which can be further applied to the promotion and use of photovoltaic power stations.

[0050] As an optional implementation of an embodiment of the present application, obtaining the first open-circuit voltage of the photovoltaic component includes: obtaining the second open-circuit voltage of the photovoltaic array and the number of series-connected cells of the photovoltaic array; and determining the first open-circuit voltage based on the second open-circuit voltage and the number of series-connected cells.

[0051] Specifically, the second open-circuit voltage V of the photovoltaic array is measured. OC,Array and the number of series cells N in the photovoltaic array S .

[0052] The first open circuit voltage V of the photovoltaic array is calculated using the following equation (5): OC,M :

[0053] As an optional implementation of an embodiment of the present application, as shown in Figure 2, step 103 includes: determining an initial point voltage based on the first open circuit voltage; determining a maximum search voltage based on the initial point voltage, the first open circuit voltage and the number of batteries in series; determining a search range based on the initial point voltage and the maximum search voltage; within the search range, based on the volt-ampere characteristic curve, searching the output power characteristic curve with the first open circuit voltage as the search step to obtain the first maximum power point.

[0054] Specifically, 0.5 times the search step length ΔV is used as the initial point voltage ΔV 1st , as shown in the following relation (6):

[0055] Maximum search voltage V LIM , that is, the last local optimal point is located at (N S -1)V OC,M and N S V OC,M The relationship between them is shown in the following equation (7): LIM =(N S -1)ΔV+ΔV 1st (7)

[0056] Optionally, the search range is the initial point voltage ΔV 1st and the maximum search voltage V LIM between.

[0057] Optionally, at the initial point voltage ΔV 1st and the maximum search voltage V LIM A search is performed in the PU characteristic curve with a search step size ΔV to obtain the first maximum power point.

[0058] Optionally, as shown in Figure 2, within the search range, based on the volt-ampere characteristic curve, the output power characteristic curve is searched with the first open-circuit voltage as the search step to obtain the first maximum power point, including: obtaining the first voltage of the photovoltaic array; determining the first current of the photovoltaic array in the volt-ampere characteristic curve based on the first voltage; determining the first power of the photovoltaic array based on the first voltage and the first current; updating the first voltage based on the search step, and obtaining the updated second voltage and second current of the photovoltaic array; determining the second power of the photovoltaic array based on the second voltage and the second current; comparing the second power with the first power; when the second power is greater than the first power, updating the first power with the second power and updating the first voltage with the second voltage, until the second voltage iterates to the maximum search voltage and stops iterating to obtain a target voltage; and determining the first maximum power point in the output power characteristic curve based on the target voltage.

[0059] Specifically, the current voltage of the photovoltaic array is measured, that is, the first voltage V PV .

[0060] Then, according to the measured first voltage V PV , the corresponding first current I can be determined in the IU characteristic curve PV .

[0061] Optionally, the current power of the photovoltaic array is calculated using the following relationship (8), that is, the first power P PV : P PV =V PV ×I PV (8)

[0062] Optionally, store the current power P of the photovoltaic array PV and the current voltage V PV , and recorded as P PV,stored and V PV,stored .

[0063] Optionally, with a search step size ΔV=V OC,M The voltage of the photovoltaic array, ie, the first voltage, is updated, and a second voltage and a second current of the updated photovoltaic array are measured.

[0064] Optionally, the second voltage and the second current are substituted into the above relational expression (8) to calculate the updated second power of the photovoltaic array.

[0065] Optionally, the second power of the photovoltaic array after updating and the first power before updating, that is, the currently recorded power P of the photovoltaic array PV,stored Make a comparison.

[0066] Optionally, when the updated second power of the photovoltaic array is greater than the currently recorded power P of the photovoltaic array PV,stored When the updated second power and second voltage are used to overwrite the currently recorded power P of the photovoltaic array, PV,stored and the currently recorded PV array voltage V PV,stored , until the second voltage of the photovoltaic array after updating reaches the maximum search voltage V LIM .

[0067] Finally, according to the second voltage of the photovoltaic array after stopping the iteration, that is, the target voltage, the global optimal point, that is, the first maximum power point, is determined in the PU characteristic curve.

[0068] As an optional implementation of an embodiment of the present application, as shown in Figure 2, after comparing the second power with the first power, the method further includes: when the second power is less than the first power, determining the first maximum power of the photovoltaic array based on the volt-ampere characteristic curve, the maximum search voltage and the second current; comparing the first maximum power with the first power; when the first maximum power is greater than the first power, repeating the steps of updating the first voltage based on the search step and obtaining the updated second voltage and second current of the photovoltaic array to determining the first maximum power point in the output power characteristic curve based on the target voltage; when the first maximum power is less than and equal to the first power, judging whether the second power is equal to the first power; when the second power is equal to the first power, taking the power point corresponding to the second power as the first maximum power point.

[0069] Specifically, when the updated second power of the photovoltaic array is less than the currently recorded power P of the photovoltaic array PV,stored When , the maximum power P that may appear after the current point on the PU characteristic curve is calculated LIM , that is, the first maximum power.

[0070] Among them, the photovoltaic array IU characteristic curve increases with the increase of photovoltaic array voltage. When it reaches the next V OC,M Before, the current will remain unchanged or decrease. In the embodiment of the present application, it is assumed that when the maximum search voltage V LIM Pre-I PV remains unchanged, the first maximum power P of the photovoltaic array LIM The following relationship (9) shows: LIM =V LIM ×I PV (9)

[0071] Optionally, the first maximum power P LIMand the currently recorded PV array power P PV,stored Make a comparison.

[0072] When the first maximum power P LIM Greater than the currently recorded photovoltaic array power P PV,stored When , it indicates that there is a larger power point in the PU characteristic curve, the voltage of the photovoltaic array is updated with the search step size ΔV, and the search is continued until the first maximum power point is obtained.

[0073] When the first maximum power P LIM Less than and equal to the currently recorded photovoltaic array power P PV,stored When the current voltage of the photovoltaic array is set to be equal to the currently recorded voltage V PV,stored , and judge the current power of the photovoltaic array, that is, whether the second power is equal to the currently recorded power P of the photovoltaic array PV,stored , that is, the first power.

[0074] Optionally, if the second power is equal to the currently recorded power P of the photovoltaic array PV,stored , the second power is stored, and the power point corresponding to the second power is used as the first maximum power point.

[0075] Optionally, if the second power is not equal to the currently recorded power P of the photovoltaic array PV,stored , then return to the above step 101.

[0076] As an optional implementation manner of an embodiment of the present application, as shown in Figure 3, step 104 includes: based on the first maximum power point, determining the third voltage of the photovoltaic array in the output power characteristic curve; based on the third voltage, determining the initialization voltage of each particle; based on the initialization voltage of each particle, calculating the first search power of each particle; based on each first search power, determining the second maximum power and the third maximum power of the photovoltaic array; updating the position and velocity of each particle, and judging whether the second maximum power is equal to the third maximum power; when the second maximum power is equal to the third maximum power, obtaining the fourth voltage and the third current of the photovoltaic array; determining the third power of the photovoltaic array based on the fourth voltage and the third current; judging whether the third power meets the preset power range; when the third power meets the preset power range, using the power point corresponding to the second maximum power as the target maximum power point.

[0077] Specifically, the third voltage of the photovoltaic array is determined in the PU characteristic curve using the first maximum power point, that is, the last stored and recorded V PV,stored .

[0078] Optionally, in the embodiment of the present application, at 0.85 to 1.15 times of V PV,stored Initialization voltage for 5 search points within the interval.

[0079] Specifically, the initialization current of each search point is determined in the IU characteristic curve according to the initialization voltage of each search point.

[0080] Optionally, according to the initialization voltage and the initialization current of each search point, the first search power of each search point can be calculated through the above relational expression (8) and the output power characteristic curve.

[0081] Optionally, each first search power is compared to obtain the local maximum power, that is, the second maximum power G best,id , that is, the second maximum power and the global maximum power, that is, the third maximum power P best,id

[0082] Optionally, update the position and velocity of each particle and determine the second maximum power G best,id Is it equal to the third maximum power P best,id .

[0083] When the second maximum power G best,id Equal to the third maximum power P best,id When the fourth voltage and the third current of the photovoltaic array are measured, the third power of the photovoltaic array can be calculated based on the measured fourth voltage and the third current using the above relationship (8).

[0084] The preset power range is determined according to the third maximum power, and is 98% of the third maximum power to 102% of the third maximum power.

[0085] Optionally, when the third power is within the above-mentioned preset power range, it indicates that the working condition of the photovoltaic array has not changed, that is, the second maximum power is the maximum power output of the photovoltaic array at this time. Optionally, the power point corresponding to the second maximum power is the target maximum power point.

[0086] Optionally, when the third power is not within the preset power range, it indicates that the working condition of the photovoltaic array has changed, and it is necessary to search for the maximum power point of the photovoltaic array from the beginning, ie, return to step 101 .

[0087] As an optional implementation of an embodiment of the present application, as shown in Figure 3, after updating the position and velocity of each particle and determining whether the second maximum power is equal to the third maximum power, the method further includes: when the second maximum power is not equal to the third maximum power, based on each updated particle, repeating the step of calculating the first search power of each particle based on the initialization voltage of each particle, and when the third power satisfies the preset power range, using the power point corresponding to the second maximum power as the target maximum power point.

[0088] Specifically, the second maximum power G best,id Not equal to the third maximum power P best,id , a precise search is performed again based on each updated particle, that is, the process returns to the step of "calculating the first search power of each particle based on the initialization voltage of each particle", and repeats the step of "taking the power point corresponding to the second maximum power as the target maximum power point when the third power satisfies the preset power range".

[0089] In one embodiment, a maximum power point tracking method based on photovoltaic array output characteristics is provided, the flow chart of which is shown in FIG4 , and includes the following steps:

[0090] Step 1: Setting the initial conditions, taking a 4×2 photovoltaic array as an example, N S 4, V OC,M The voltage is 43.6 V. The equivalent circuit diagram of the photovoltaic array used is shown in FIG5 , and the output characteristic curve of the photovoltaic array is shown in FIG6 .

[0091] 1. Set the step size ΔV:

[0092] Among them, V OC,Array is the open circuit voltage of the photovoltaic array.

[0093] 2. Set the initial point ΔV 1st :

[0094] 3. Set the maximum search voltage V LIM : V LIM =(N S -1)ΔV+ΔV 1st

[0095] The purpose of this step is to provide the initial value and search range for step 2.

[0096] Step 2: Search for the global optimum (maximum power point of the PU characteristic curve)

[0097] 1. Set the initial voltage V of the photovoltaic arrayPV : V PV =ΔV 1st

[0098] 2. Measure the photovoltaic array voltage V PV , current I PV , calculate the photovoltaic array power P PV : P PV =V PV ×I PV

[0099] 3.Storage of photovoltaic array power P PV , PV array voltage V PV .

[0100] 4. Update the photovoltaic array voltage V PV =ΔV PV,stored +ΔV.

[0101] 5. Measure V after updating the voltage PV , I PV , calculate P PV .

[0102] 6. Determine P PV Is it greater than P PV,stored .

[0103] 7. If P PV Greater than P PV,stored , then overwrite P PV,stored and V PV,stored After overwriting, judge V PV Is it equal to V LIM If not equal, go back to step 4; if equal, go to step 3.

[0104] 8. If P PV Less than or equal to P PV,stored , then calculate P LIM =V LIM ×I PV .

[0105] 9. Determine P LIM Is it greater than P PV,stored .

[0106] 10. If P LIM Greater than P PV,stored Then return to step 4.

[0107] 11. If P LIM Less than or equal to P PV,stored , then set V PV Equal to V PV,stored .

[0108] 12. Determine P PVIs it equal to P PV,stored , if P PV Equal to P PV,stored Go to step 3; if P PV Not equal to P PV,stored , then return to step 1.

[0109] Step 3: Use particle swarm optimization to search for the actual maximum power point.

[0110] 1. Continue with step 2 and use the V stored at the end of step 2 PV,stored (i.e. the global optimal point obtained in step 2), between 0.85 and 1.15 times V PV,stored Initialize voltage for 5 particles within the interval;

[0111] 2. Calculate the power of each particle point;

[0112] 3. Compare the power to obtain the global maximum power and the historical maximum power (local maximum power);

[0113] 4. Update the position and velocity of the particle point;

[0114] 5. Determine whether the maximum power point has been reached;

[0115] 6. If the maximum power point has not been reached, go to step 2, otherwise go to step 7;

[0116] 7. Store the maximum power point P GM ;

[0117] 8. Measure V PV , I PV , calculate P PV ;

[0118] 9. Determine P PV Is it 98% P GM to 102%P GM between;

[0119] 10. If the answer to step 9 is yes, go to step 8. This power is the actual maximum power point of the photovoltaic array;

[0120] 11. If the judgment of 9 is no, return to step 1.

[0121] The present application also provides a maximum power point tracking device based on the output characteristics of a photovoltaic array, as shown in FIG7 . The photovoltaic array includes photovoltaic modules. The device includes:

[0122] The acquisition module 201 is used to acquire the output voltage and output current of the photovoltaic array and the first open-circuit voltage of the photovoltaic module; for details, please refer to the relevant description of step 101 in the above method embodiment.

[0123] The determination module 202 is configured to determine the volt-ampere characteristic curve and the output power characteristic curve of the photovoltaic array based on the output voltage and the output current. For details, see the description of step 102 in the above method embodiment.

[0124] The search module 203 is configured to use the first open-circuit voltage as a search step, utilize the distribution principle that the local optimal points of the volt-ampere characteristic curve and the output power characteristic curve are uniformly distributed based on the first open-circuit voltage, search the output power characteristic curve, and obtain a first maximum power point; for details, see the relevant description of step 103 in the above method embodiment.

[0125] The processing module 204 is configured to obtain a target maximum power point of the photovoltaic array based on the first maximum power point through a particle swarm algorithm. For details, see the description of step 104 in the above method embodiment.

[0126] The maximum power point tracking device based on the output characteristics of a photovoltaic array, provided in an embodiment of the present application, utilizes the characteristic that each local optimum of the photovoltaic array output power characteristic curve is located near an integer multiple of the photovoltaic module open-circuit voltage. That is, each local optimum is evenly distributed based on the photovoltaic module open-circuit voltage. By simply searching the output power characteristic curve using the photovoltaic module open-circuit voltage as the search step, the global optimum of the output power characteristic curve, i.e., the first maximum power point, can be quickly located. Compared with traditional tracking methods, there is no need to scan the entire photovoltaic array output power characteristic curve, greatly improving the search speed. Simultaneously, a particle swarm algorithm is used for precise search to obtain the actual global optimum of the output power characteristic curve, i.e., the target maximum power point, preventing the algorithm from falling into a local optimum. Furthermore, the search process utilizes the inherent characteristics of the photovoltaic array during operation, which provides universal applicability and high reliability, and can be further promoted and used in photovoltaic power stations.

[0127] As an optional implementation of an embodiment of the present application, the acquisition module includes: a first acquisition submodule, used to obtain the second open-circuit voltage of the photovoltaic array and the number of series-connected batteries of the photovoltaic array; a first determination submodule, used to determine the first open-circuit voltage based on the second open-circuit voltage and the number of series-connected batteries.

[0128] As an optional implementation of an embodiment of the present application, the search module includes: a second determination submodule, used to determine the initial point voltage based on the first open circuit voltage; a third determination submodule, used to determine the maximum search voltage based on the initial point voltage, the first open circuit voltage and the number of batteries in series; a fourth determination submodule, used to determine the search range based on the initial point voltage and the maximum search voltage; a search submodule, used to search in the output power characteristic curve within the search range based on the volt-ampere characteristic curve and with the first open circuit voltage as the search step to obtain the first maximum power point.

[0129] As an optional implementation manner of the embodiment of the present application, the search submodule includes: a second acquisition submodule for acquiring a first voltage of the photovoltaic array; a fifth determination submodule for determining a first current of the photovoltaic array in the volt-ampere characteristic curve based on the first voltage; a sixth determination submodule for determining a first power of the photovoltaic array based on the first voltage and the first current; an update and acquisition submodule for updating the first voltage based on the search step and acquiring an updated second voltage and second current of the photovoltaic array; a seventh determination submodule for determining a second power of the photovoltaic array based on the second voltage and the second current; a first comparison submodule for comparing the second power with the first power; an iterative update submodule for updating the first power using the second power and updating the first voltage using the second voltage when the second power is greater than the first power, and stopping the iteration when the second voltage iterates to the maximum search voltage to obtain a target voltage; and an eighth determination submodule for determining the first maximum power point in the output power characteristic curve based on the target voltage.

[0130] As an optional implementation manner of an embodiment of the present application, the search submodule further includes: a ninth determination submodule, for determining the first maximum power of the photovoltaic array based on the volt-ampere characteristic curve, the maximum search voltage and the second current when the second power is less than the first power; a second comparison submodule, for comparing the first maximum power with the first power; a first repetition submodule, for repeating the steps of updating the first voltage based on the search step and obtaining the updated second voltage and second current of the photovoltaic array to determining the first maximum power point in the output power characteristic curve based on the target voltage when the first maximum power is greater than the first power; a first judgment submodule, for judging whether the second power is equal to the first power when the first maximum power is less than and equal to the first power; and a tenth determination submodule, for taking the power point corresponding to the second power as the first maximum power point when the second power is equal to the first power.

[0131] As an optional implementation manner of the embodiment of the present application, the processing module includes: an eleventh determination submodule for determining a third voltage of the photovoltaic array in the output power characteristic curve based on the first maximum power point; a twelfth determination submodule for determining an initialization voltage of each particle based on the third voltage; a calculation submodule for calculating a first search power of each particle based on the initialization voltage of each particle; a thirteenth determination submodule for determining a second maximum power and a third maximum power of the photovoltaic array based on each first search power; an update and judgment submodule for updating the position and velocity of each particle and judging whether the second maximum power is equal to the third maximum power; a third acquisition submodule for acquiring a fourth voltage and a third current of the photovoltaic array when the second maximum power is equal to the third maximum power; a fourteenth determination submodule for determining a third power of the photovoltaic array based on the fourth voltage and the third current; a second judgment submodule for judging whether the third power satisfies a preset power range; and a fifteenth determination submodule for, when the third power satisfies the preset power range, using the power point corresponding to the second maximum power as the target maximum power point.

[0132] As an optional implementation manner of an embodiment of the present application, the processing module further includes: a second repeating submodule, which is used to repeat the step of calculating the first search power of each particle based on the initialization voltage of each particle based on each updated particle when the second maximum power is not equal to the third maximum power, and to use the power point corresponding to the second maximum power as the target maximum power point when the third power satisfies the preset power range.

[0133] For a detailed description of the functions of the maximum power point tracking device based on the output characteristics of the photovoltaic array provided in the embodiments of the present application, please refer to the description of the maximum power point tracking method based on the output characteristics of the photovoltaic array in the above embodiments.

[0134] The present application also provides a storage medium, as shown in FIG8 , storing a computer program 301. When executed by a processor, the program implements the steps of the maximum power point tracking method based on the output characteristics of a photovoltaic array described in the above embodiment. The storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM), a random access memory (RAM), a flash memory, a hard disk drive (HDD), or a solid-state drive (SSD). The storage medium may also include a combination of the aforementioned types of memory.

[0135] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), a random access memory (RAM), a flash memory, a hard disk drive (HDD), or a solid-state drive (SSD). The storage medium can also include a combination of the above-mentioned types of memory.

[0136] An embodiment of the present application also provides an electronic device, as shown in FIG9 , which may include a processor 41 and a memory 42 , wherein the processor 41 and the memory 42 may be connected via a bus or other means, with FIG9 taking the bus connection as an example.

[0137] The processor 41 may be a central processing unit (CPU). The processor 41 may 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 gate or transistor logic devices, discrete hardware components, or a combination of the above chips.

[0138] Memory 42, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer executable programs, and modules, such as the corresponding program instructions / modules in the embodiments of the present application. Processor 41 executes the non-transitory software programs, instructions, and modules stored in memory 42 to perform various processor functions and data processing, thereby implementing the maximum power point tracking method based on the output characteristics of the photovoltaic array in the above-mentioned method embodiment.

[0139] The memory 42 may include a program storage area and a data storage area, wherein the program storage area may store applications required for operating the device and at least one function; the data storage area may store data created by the processor 41, etc. In addition, the memory 42 may include a high-speed random access memory and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory 42 may optionally include a memory remotely located relative to the processor 41, and these remote memories may be connected to the processor 41 via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0140] The one or more modules are stored in the memory 42 , and when executed by the processor 41 , perform the maximum power point tracking method based on the output characteristics of the photovoltaic array in the embodiments shown in FIG. 1-6 .

[0141] The specific details of the above electronic device can be understood by referring to the corresponding descriptions and effects in the embodiments shown in Figures 1 to 6, and will not be repeated here.

[0142] Although the embodiments of the present application have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present application, and such modifications and variations shall fall within the scope defined by the appended claims.

Claims

1. A maximum power point tracking method based on photovoltaic array output characteristics, characterized in that: The photovoltaic array includes a photovoltaic component; the method includes: Obtaining the output voltage, output current of the photovoltaic array and the first open-circuit voltage of the photovoltaic component; Based on the output voltage and the output current, determining a volt-ampere characteristic curve and an output power characteristic curve of the photovoltaic array; Taking the first open circuit voltage as the search step length, utilizing the distribution principle that the local optimum points of the volt-ampere characteristic curve and the output power characteristic curve are uniformly distributed with the first open circuit voltage as the base, searching in the output power characteristic curve to obtain a first maximum power point; Based on the first maximum power point, a target maximum power point of the photovoltaic array is obtained through particle swarm algorithm processing.

2. The method according to claim 1, characterized in that: Obtaining a first open-circuit voltage of the photovoltaic component includes: Obtaining a second open circuit voltage of the photovoltaic array and the number of batteries connected in series in the photovoltaic array; The first open circuit voltage is determined based on the second open circuit voltage and the number of batteries connected in series.

3. The method according to claim 2, characterized in that Taking the first open circuit voltage as the search step length, utilizing the distribution principle that the local optimal points of the volt-ampere characteristic curve and the output power characteristic curve are uniformly distributed with the first open circuit voltage as the base, searching in the output power characteristic curve to obtain a first maximum power point, including: Based on the first open circuit voltage, determining an initial point voltage; Determining a maximum search voltage based on the initial point voltage, the first open circuit voltage, and the number of batteries in series; determining a search range based on the initial point voltage and the maximum search voltage; In the search range, based on the volt-ampere characteristic curve, the output power characteristic curve is searched with the first open circuit voltage as the search step to obtain the first maximum power point.

4. The method according to claim 3, characterized in that In the search range, based on the volt-ampere characteristic curve, searching in the output power characteristic curve with the first open circuit voltage as the search step length to obtain the first maximum power point includes: Acquiring a first voltage of the photovoltaic array; determining a first current of the photovoltaic array in the volt-ampere characteristic curve based on the first voltage; determining a first power of the photovoltaic array based on the first voltage and the first current; updating the first voltage based on the search step size, and acquiring an updated second voltage and a second current of the photovoltaic array; determining a second power of the photovoltaic array based on the second voltage and the second current; comparing the second power with the first power; When the second power is greater than the first power, the first power is updated by using the second power and the first voltage is updated by using the second voltage until the second voltage iterates to the maximum search voltage and the iteration is stopped to obtain a target voltage; Based on the target voltage, the first maximum power point is determined in the output power characteristic curve.

5. The method according to claim 4, characterized in that After comparing the second power with the first power, the method further includes: When the second power is less than the first power, determining a first maximum power of the photovoltaic array based on the volt-ampere characteristic curve, the maximum search voltage and the second current; comparing the first maximum power with the first power; When the first maximum power is greater than the first power, repeating the steps of updating the first voltage based on the search step size and acquiring the updated second voltage and second current of the photovoltaic array to determining the first maximum power point in the output power characteristic curve based on the target voltage; When the first maximum power is less than and equal to the first power, determining whether the second power is equal to the first power; When the second power is equal to the first power, a power point corresponding to the second power is used as the first maximum power point.

6. The method according to claim 1, characterized in that Based on the first maximum power point, a target maximum power point of the photovoltaic array is obtained through particle swarm algorithm processing, including: determining a third voltage of the photovoltaic array in the output power characteristic curve based on the first maximum power point; Based on the third voltage, determining an initialization voltage for each particle; Calculating a first search power of each of the particles based on the initialization voltage of each of the particles; determining a second maximum power and a third maximum power of the photovoltaic array based on each of the first search powers; updating the position and velocity of each of the particles, and determining whether the second maximum power is equal to the third maximum power; When the second maximum power is equal to the third maximum power, obtaining a fourth voltage and a third current of the photovoltaic array; determining a third power of the photovoltaic array based on the fourth voltage and the third current; Determining whether the third power meets a preset power range; When the third power satisfies the preset power range, a power point corresponding to the second maximum power is used as the target maximum power point.

7. The method according to claim 6, characterized in that After updating the position and velocity of each particle and determining whether the second maximum power is equal to the third maximum power, the method further includes: When the second maximum power is not equal to the third maximum power, based on each of the updated particles, repeating the step of calculating the first search power of each of the particles based on the initialization voltage of each of the particles until when the third power satisfies the preset power range, taking the power point corresponding to the second maximum power as the target maximum power point.

8. A maximum power point tracking device based on photovoltaic array output characteristics, characterized in that: The photovoltaic array includes a photovoltaic component; the device includes: An acquisition module, used for acquiring the output voltage and output current of the photovoltaic array and the first open-circuit voltage of the photovoltaic component; A determination module, used to determine a volt-ampere characteristic curve and an output power characteristic curve of the photovoltaic array based on the output voltage and the output current; A search module, configured to use the first open circuit voltage as a search step length, and utilize a distribution principle that local optimal points of the volt-ampere characteristic curve and the output power characteristic curve are uniformly distributed based on the first open circuit voltage to search the output power characteristic curve to obtain a first maximum power point; A processing module is used to obtain a target maximum power point of the photovoltaic array based on the first maximum power point through a particle swarm algorithm.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and the computer program is used to enable the computer to execute the maximum power point tracking method based on the output characteristics of the photovoltaic array according to any one of claims 1 to 7.

10. An electronic device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores a computer program, and the processor executes the maximum power point tracking method based on the output characteristics of a photovoltaic array as described in any one of claims 1 to 7 by executing the computer program.

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