A control system and shadow reconstruction method for improving output power of a SP structure photovoltaic array under local shadow

Abstract

The application provides a control system and a shadow reconstruction method for improving the output power of a SP structure photovoltaic array under local shadow, which comprises a shadow detection module, a DSP controller, an isolation circuit, a driving circuit, a switch group and a SP structure photovoltaic array connected in sequence. The shadow reconstruction method comprises the following steps: real-time sampling the output voltage and current of each component of the photovoltaic array, transmitting the voltage and current to the DSP controller after power detection and signal amplification. The DSP determines whether the component is blocked by the shadow. If the component is blocked, a PWM signal is generated according to the shadow reconstruction rule, the PWM signal is converted into an optical signal or an encoded pulse by the isolation circuit, and then the optical signal or the encoded pulse is restored into an electrical signal and transmitted to the driving circuit. The driving circuit controls the on-off of the switch group, so that the blocked component and the unblocked component are exchanged, and the shadow reconstruction is realized. The technical scheme of the application can reduce the negative influence of local shadow on the photovoltaic system and improve the power generation efficiency of the photovoltaic system.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic power generation technology, specifically relating to a control system and shadow reconstruction method for improving the output power of SP structure photovoltaic arrays under local shading. Background Technology

[0002] Solar photovoltaic (PV) power generation has become an important component of the new energy power generation field due to its advantages such as being clean, renewable, and widely distributed. In actual PV power generation systems, PV modules are typically arranged into PV arrays according to certain electrical connection methods to meet the system's requirements for output voltage, current, and power levels. Among them, the series-parallel structure, or SP structure PV array, is a common array connection form in engineering applications. This structure forms branches by connecting multiple PV modules in series, and then connecting multiple branches in parallel for output. It has advantages such as simple structure, convenient expansion, and low cost, and is widely used in distributed PV power stations, building-integrated photovoltaic (BIPV) systems, and small and medium-sized PV power generation scenarios.

[0003] However, in actual operation of photovoltaic (PV) arrays, illumination conditions are often uneven. Affected by factors such as cloud cover, tree shadows, building obstruction, dust accumulation, bird droppings, differences in module aging, and projection from surrounding equipment, PV arrays are prone to localized shading. Localized shading refers to a situation where some PV modules or localized areas of a module receive significantly less solar irradiance than other modules. Since the output current of PV modules is closely related to light intensity, when individual modules in a series circuit are shaded, their output current capability decreases, limiting the current output of the entire series circuit, leading to a decrease in branch power, and even causing reverse bias and hot spot effects in the shaded modules, affecting the safety and lifespan of the PV modules. For SP (Special Partition) structure PV arrays, localized shading not only reduces the output power of the shaded module itself but also affects the output characteristics of adjacent modules and the entire array through series-parallel electrical coupling. Under uneven irradiation conditions, current and voltage mismatches between series branches can lead to multiple local peaks in the array's power-voltage characteristic curve. This makes it difficult for traditional maximum power point tracking (MPPT) control algorithms to accurately and quickly track the global maximum power point, resulting in significant power generation losses. Especially in application environments with frequent changes in local shading, the output power of the photovoltaic array fluctuates significantly, affecting both system power generation efficiency and stability.

[0004] To mitigate the impact of localized shading on the output power of photovoltaic (PV) arrays, existing technologies typically employ bypass diodes, improved maximum power point tracking (MPPT) algorithms, module-level power optimizers, micro-inverters, and PV array electrical reconfiguration. Bypass diodes provide a bypass path for current when modules are severely shaded, preventing hot spot problems. However, their primary function is module protection; they cannot fundamentally optimize the overall power distribution of the array. Furthermore, the conduction of bypass diodes causes some modules to lose their power generation contribution, resulting in power loss. Improved MPPT algorithms can enhance optimization capabilities under complex power curves to some extent, but their control effectiveness is significantly affected by algorithm speed, sampling accuracy, and the rate of environmental change, and they cannot address the mismatch between modules within the array.

[0005] Module-level power optimizers and microinverters can independently regulate the power of individual modules and have good local shading adaptability. However, these solutions typically require independent power electronic conversion devices on each photovoltaic module, resulting in high system costs, complex control structures, increased maintenance difficulty, and significant device losses and reliability issues in large-scale photovoltaic arrays. Photovoltaic array reconfiguration technology, on the other hand, changes the electrical connections between modules to make the shading distribution more uniform across the array, thereby reducing mismatch losses and increasing array output power. Theoretically, this method has good power enhancement effects, but existing reconfiguration methods often require a large number of switching devices, complex topology designs, and cumbersome control strategies. Some solutions also require large-scale connection switching of the entire array, resulting in high implementation costs and insufficient real-time control and engineering feasibility.

[0006] Therefore, how to identify local shading conditions in real time and quickly adjust the electrical position of photovoltaic modules through reasonable switching control, while ensuring a simple system structure, low cost, and reliable control, has become a crucial technical issue for improving the output power of SP structure photovoltaic arrays. However, existing technologies lack control systems and shading reconstruction methods for directional position swapping between modules in SP structure photovoltaic arrays, especially lacking a complete control scheme that combines shading detection, DSP control, isolation drive, and coordinated operation of switching groups. There is an urgent need to propose a control system and shading reconstruction method suitable for improving the output power of SP structure photovoltaic arrays under local shading conditions. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a control system and shadow reconstruction method for improving the output power of SP structure photovoltaic array under local shadow, which can reduce the negative impact of local shadow on photovoltaic system and improve the power generation efficiency of photovoltaic system.

[0008] To achieve the above objectives, the present invention provides the following solution: A control system for improving the output power of an SP structure photovoltaic array under partial shading includes: a shading detection module, a DSP controller, an isolation circuit, a drive circuit, a switch group, and an SP structure photovoltaic array connected in sequence.

[0009] Preferably, the SP structure photovoltaic array includes several columns, with each pair of columns forming an associated group; in the first column of the associated group, except for the first photovoltaic module, the remaining photovoltaic modules are numbered sequentially with numbers; in the second column of the associated group, except for the last photovoltaic module, the remaining photovoltaic modules are numbered sequentially with numbers.

[0010] Preferably, the shadow detection module includes a power detection module, a signal amplification module, and a power supply module. The input terminal of the power detection module is connected to the output voltage terminal and the output current terminal of each photovoltaic module in the SP structure photovoltaic array, respectively. The output terminal of the power detection module is connected to the input terminal of the signal amplification module, and the output terminal of the signal amplification module is connected to the input terminal of the DSP controller. The power supply module provides operating voltage to the power detection module, the signal amplification module, and the DSP controller, respectively.

[0011] Preferably, the switch group adopts the following configuration: a switch S is connected in series at the input terminal of each numbered photovoltaic module. n ,in, n =1, 2, 3, ..., N; a switch S is connected in series with the output terminal of the last numbered photovoltaic module in each column. N+1 ; A switch is configured between the two columns of photovoltaic modules within each associated group. The configuration structure includes: a switch S' is configured between the front end of the input switch of the numbered modules in the first column and the rear end of the input switch of the same numbered modules in the second column. n A switch S'' is configured between the rear end of the numbered input switch in the first column and the front end of the numbered input switch in the second column. n A switch S is configured between the front end of the last numbered output switch in the first column and the rear end of the last numbered output switch in the second column. ' N+1 A switch S is configured between the rear end of the last numbered output switch in the first column and the front end of the last numbered output switch in the second column. '' N+1 .

[0012] Preferably, the initial state of the switch includes: S n and S N+1 When S' is in the off state n and S' N+1 S'' is in the disconnected state. n and S'' N+1 It is in the disconnected state.

[0013] This invention also provides a shading reconstruction method for improving the output power of an SP structure photovoltaic array under local shading, utilizing the aforementioned control system, including: The output voltage and output current of each photovoltaic module in the photovoltaic array are sampled in real time using the shadow detection module, and the power signal of each photovoltaic module is output after processing. The signal amplification module receives the power signal, amplifies it, and then transmits it to the DSP controller. The DSP controller determines whether each photovoltaic module is shaded based on the amplified power signal. When it is determined that there is a shaded photovoltaic module, the DSP controller generates the corresponding pulse width modulation (PWM) logic signal according to the shading reconstruction rule algorithm and sends it to the isolation circuit. The isolation circuit converts the pulse width modulation (PWM) logic signal into an optical signal or coded pulse for transmission, and the transmitted signal is restored to an electrical signal and sent to the drive circuit. The drive circuit controls the switching group to turn on and off according to the isolated electrical signal, so that the position of the photovoltaic module that is shaded is interchanged with that of the unshaded photovoltaic module, thereby realizing shadow reconstruction.

[0014] Preferably, the shadow reconstruction rules include: if there is no shadow shading, then maintain the initial state of each switch; if in a certain association group, a photovoltaic module with number n in the second column is shaded and the photovoltaic module with the same number in the first column is not shaded, then disconnect the switch S at the input terminals of the two photovoltaic modules with number n in the association group. n and the output switch S n+1 Simultaneously, close switch S' between the front end of the input / output switch of the first column n photovoltaic module and the rear end of the input / output switch of the second column n module. n and S' n+1 And the switch S'' between the rear end of the input / output switch of component n in the first column and the front end of the input / output switch of component n in the second column. n and S'' n+1 This allows the photovoltaic modules that are shaded to swap positions with unshaded photovoltaic modules of the same number in the associated group; if the shading disappears, the switch returns to its initial state.

[0015] Compared with existing technologies, the advantages of this invention are as follows: It maintains the normal initial connection state of the array when there is no shading; when a specific component is detected to be partially shaded, the electrical positions of the shaded component and the unshaded component in the associated group are interchanged through selective switching of the switching group, reducing the limitation of the current in the same series branch by local shading, reducing the degree of electrical mismatch between components, improving the equivalent output capability of the array, and restoring the initial state after the shading disappears. Without increasing the number of module-level power conversion devices, it reduces the mismatch loss caused by local shading, improves the maximum output power and power generation efficiency of the photovoltaic array, while simultaneously considering system cost, real-time control, and engineering implementation difficulty. In summary, the system and method of this invention can reduce the negative impact of local shading on the entire SP structure photovoltaic array system in real time, increase the maximum output power of the photovoltaic array, and effectively improve the power generation efficiency of the photovoltaic system. Compared with modular and reconfigurable photovoltaic power generation systems, this method is more effective, easier to implement, and lower in cost. Attached Figure Description

[0016] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the control system for improving the output power of an SP structure photovoltaic array under partial shading according to the present invention; Figure 2 This is a schematic diagram of the on / off state of the control system of the present invention when the shadow is partially obscured. Figure 3 Figure 1 shows a schematic diagram of the shadow detection module. Figure 4 This is a graph showing the output P_U characteristic curves of the photovoltaic array in Embodiment 1 of the present invention before and after shadow reconstruction; Figure 4 In the diagram, A represents the output P_U characteristic curve before shadow reconstruction, and B represents the output P_U characteristic curve after shadow reconstruction. Figure 5 This is a graph showing the output P_U characteristic curves of the photovoltaic array before and after shadow reconstruction in Embodiment 2 of the present invention; Figure 5 In the diagram, C represents the output P_U characteristic curve before shadow reconstruction, and D represents the output P_U characteristic after shadow reconstruction. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] Example 1: like Figure 1 As shown, a control system for improving the output power of an SP structure photovoltaic array under partial shading includes: a shading detection module, a DSP controller, an isolation circuit, a drive circuit, a switch group, and an SP structure photovoltaic array connected in sequence. Specifically, the shading detection module is connected to the DSP controller, the DSP controller is linked to the isolation circuit, the isolation circuit is linked to the drive circuit, the drive circuit is connected to the switch group, and the switch group is connected to the photovoltaic array.

[0021] A further implementation involves an SP structure photovoltaic array comprising several columns, with each pair of columns forming an associated group; in the first column of the associated group, all photovoltaic modules except the first one are sequentially numbered; in the second column of the associated group, all photovoltaic modules except the last one are sequentially numbered. For example... Figure 1 As shown, the SP structure photovoltaic array includes several columns, each column is connected in series with N+1 photovoltaic modules, and every two columns form an association group; in the first column of the association group, except for the first photovoltaic module, the remaining photovoltaic modules are numbered sequentially with numbers, i.e., 1, 2, 3, ..., N; in the second column of the association group, except for the last photovoltaic module, the remaining photovoltaic modules are numbered sequentially with numbers, i.e., 1, 2, 3, ..., N.

[0022] A further implementation method is, such as Figure 3 As shown, the shadow detection module includes a power detection module, a signal amplification module, and a power supply module. The input terminals of the power detection module are connected to the output voltage and output current terminals of each photovoltaic module in the SP structure photovoltaic array, respectively. The output terminal of the power detection module is connected to the input terminal of the signal amplification module, and the output terminal of the signal amplification module is connected to the input terminal of the DSP controller. The power supply module provides operating voltage to the power detection module, the signal amplification module, and the DSP controller. The power detection module uses the HLW8012 power measurement chip.

[0023] A further implementation involves a switch group configured as follows: a switch S is connected in series with the input terminal of each numbered photovoltaic module. n,in, n =1, 2, 3, ..., N; a switch S is connected in series with the output terminal of the last numbered photovoltaic module in each column. N+1 For example, in group 1, the photovoltaic module numbered 1 in the first column has a switch S1 connected in series at its input terminal; the photovoltaic module numbered 2 in the first column has a switch S2 connected in series at its input terminal; and so on for the remaining photovoltaic modules in this column. Similarly, the photovoltaic module numbered 1 in the second column has a switch S1 connected in series at its input terminal; the photovoltaic module numbered 2 in the second column has a switch S2 connected in series at its input terminal; and so on for the remaining photovoltaic modules in this column. The output terminal of the last numbered photovoltaic module in both the first and second columns is connected in series with a switch S1. N+1 The other related groups are similar.

[0024] A switch is configured between the two columns of photovoltaic modules within each associated group. The configuration structure includes: a switch S' is configured between the front end of the input switch of the numbered modules in the first column and the rear end of the input switch of the same numbered modules in the second column. n A switch S'' is configured between the rear end of the numbered input switch in the first column and the front end of the numbered input switch in the second column. n A switch S is configured between the front end of the last numbered output switch in the first column and the rear end of the last numbered output switch in the second column. ' N+1 A switch S is configured between the rear end of the last numbered output switch in the first column and the front end of the last numbered output switch in the second column. '' N+1 .

[0025] For example, in associated group 1, a switch S'1 is configured between the front end of the input switch of component 1 in the first column and the rear end of the input switch of component 1 in the second column, and a switch S''1 is configured between the rear end of the input switch of component 1 in the first column and the front end of the input switch of component 1 in the second column, and so on for the remaining components. A switch S''1 is configured between the front end of the output switch of the last component in the first column (component N) and the rear end of the output switch of component N in the second column. ' N+1 A switch S is configured between the rear end of the output switch of component N in the first column and the front end of the output switch of component N in the second column. '' N+1 The other associated groups are similar. In the switch, S... n With S' n There is a public link between them, S n With S'' n There are common links between them, for example, there is a common link between S1 and S'1, and a common link between S1 and S''1.

[0026] A further implementation method wherein the initial state of the switch includes: S n and S N+1 When S' is in the off state n and S' N+1 S'' is in the disconnected state. n and S'' N+1 It is in the disconnected state.

[0027] Example 2 This invention also provides a shading reconstruction method for improving the output power of an SP structure photovoltaic array under local shading, applying the control system of Embodiment 1, including: S1: The output voltage and output current of each photovoltaic module in the photovoltaic array are sampled in real time using the shadow detection module, and the power signal of each photovoltaic module is output after processing. S2: The signal amplification module receives the power signal, amplifies it, and then transmits it to the DSP controller. S3: The DSP controller determines whether each photovoltaic module is shaded based on the amplified power signal; when it is determined that there is a shaded photovoltaic module, the DSP controller generates the corresponding pulse width modulation (PWM) logic signal according to the shadow reconstruction rule algorithm and sends it to the isolation circuit. S4: The isolation circuit converts the pulse width modulation (PWM) logic signal into an optical signal or coded pulse for transmission, and the transmitted signal is restored to an electrical signal and sent to the drive circuit. S5: The drive circuit enhances the isolated weak signal into a strong drive required by the power switch, controls the turn-off of the switch group, and enables the photovoltaic modules that are shaded to swap positions with those that are not shaded, thus reconstructing the shadow.

[0028] Repeat steps S1 to S5 to improve the real-time output power of the photovoltaic array.

[0029] A further implementation method includes the following shadow reconstruction rules: if there is no shadow shading, maintain the initial state of each switch; if in a certain association group, a photovoltaic module with number n in the second column is shaded and the photovoltaic module with the same number in the first column is not shaded, then disconnect the switch S at the input terminals of the two photovoltaic modules with number n in the association group. n and the output switch S n+1 Simultaneously, close switch S' between the front end of the input / output switch of the first column n photovoltaic module and the rear end of the input / output switch of the second column n module. n and S' n+1 And the switch S'' between the rear end of the input / output switch of component n in the first column and the front end of the input / output switch of component n in the second column.n and S'' n+1 This allows the photovoltaic modules that are shaded to swap positions with unshaded photovoltaic modules of the same number in the associated group; if the shading disappears, the switch returns to its initial state.

[0030] Example 2 like Figure 2 As shown, in this embodiment, the SP structure photovoltaic array (4 rows and 4 columns) is partially obscured by the shadows formed by clouds. The shadow detection module detects that the first photovoltaic module in the first column and the No. 1 photovoltaic module in the second column of the associated group 1 are shaded (shading coefficient is 0.6), while the No. 1 photovoltaic module in the first column is not shaded. Based on the detection results of the shadow detection module, the DSP controller controls the switches in the switch group to turn off to realize shadow reconstruction and minimize the number of photovoltaic modules in the second column that are shaded. Therefore, at this time, it is only necessary to exchange the positions of the No. 1 photovoltaic module in the first column and the No. 1 photovoltaic module in the second column, that is, to open the switches S1 and S2 and close the switches S'1, S''1, S'2, and S''2 at the same time, thus realizing shadow reconstruction.

[0031] like Figure 4 As shown, before shadow reconstruction, the maximum output power point P of the photovoltaic array is... A The power value at point P is 2805.72W, and the maximum power point is P. A The voltage at point P is 119.06V. After shading reconstruction, the maximum output power point P of the photovoltaic array is... B The power value at point P increases to 3097.33W, and the maximum power point P... B The voltage at that location is 116.89V. It can be seen that after shadow reconstruction, the maximum output power of the SP structure photovoltaic array increased by 291.61W, or 10.39%.

[0032] Example 3 In this embodiment, the SP structure photovoltaic array (4 rows and 4 columns) is partially obscured by the shadows cast by the building. The shadow detection module detects that in associated group 1, the first photovoltaic module in the first column and the first photovoltaic module in the second column are shaded (shading coefficient of 0.6), while the first photovoltaic module in the first column is not shaded. Similarly, in associated group 2, the first photovoltaic module in the first column and the first photovoltaic module in the second column are shaded (shading coefficient of 0.6), while the first photovoltaic module in the first column is not shaded. Based on the detection results from the shadow detection module, the DSP controller controls the switches in the switch group to turn off to achieve shadow reconstruction, minimizing the number of photovoltaic modules in the second column shaded in each associated group. Therefore, it is only necessary to swap the positions of the first photovoltaic module in the first column and the first photovoltaic module in the second column in associated groups 1 and 2, respectively, that is, to disconnect switches S1 and S2 in associated groups 1 and 2, and simultaneously close switches S'1, S''1, S'2, and S''2, thus achieving shadow reconstruction.

[0033] like Figure 5 As shown, before shadow reconstruction, the maximum output power point P of the photovoltaic array is... C The power value at point P is 2531.64.0W, and the maximum power point is P. C The voltage at point P is 86.03V. After shading reconstruction, the maximum output power point P of the photovoltaic array is... D The power value at point P becomes 2794.16W, and the maximum power point P... D The voltage at that location is 118.34V. It can be seen that after shadow reconstruction, the maximum output power of the photovoltaic array increased by 632.0 W, or 10.36%.

[0034] The following conclusions can be drawn from the above examples: This invention discloses a control system and shadow reconstruction method for improving the output efficiency of a SP photovoltaic array under local shading. It can increase the maximum output power of the photovoltaic array by approximately 10%, reduce the negative impact of local shading on the entire photovoltaic system in real time, and effectively improve the power generation efficiency of the photovoltaic system. The differences between this invention and existing technologies (CN201710069786.6) are: 1. The photovoltaic array structure is different; this invention uses the most commonly used SP structure in current practical systems and has practical application significance; 2. The switch group connection structure is different, resulting in a system that uses fewer switches and is more economical.

[0035] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A control system for improving the output power of an SP structure photovoltaic array under partial shading, characterized in that, include: The components connected in sequence are a shadow detection module, a DSP controller, an isolation circuit, a drive circuit, a switch group, and an SP structure photovoltaic array.

2. The system according to claim 1, characterized in that, The SP structure photovoltaic array includes several columns, with each pair of columns forming an associated group; in the first column of the associated group, except for the first photovoltaic module, the remaining photovoltaic modules are numbered sequentially with numbers; in the second column of the associated group, except for the last photovoltaic module, the remaining photovoltaic modules are numbered sequentially with numbers.

3. The system according to claim 2, characterized in that, The shadow detection module includes a power detection module, a signal amplification module, and a power supply module. The input terminal of the power detection module is connected to the output voltage terminal and the output current terminal of each photovoltaic module in the SP structure photovoltaic array, respectively. The output terminal of the power detection module is connected to the input terminal of the signal amplification module, and the output terminal of the signal amplification module is connected to the input terminal of the DSP controller. The power supply module provides operating voltage to the power detection module, the signal amplification module, and the DSP controller, respectively.

4. The system according to claim 2, characterized in that, The switch group adopts the following configuration: a switch S is connected in series at the input terminal of each numbered photovoltaic module. n ,in, n =1, 2, 3, ..., N; a switch S is connected in series with the output terminal of the last numbered photovoltaic module in each column. N+1 ; A switch is configured between the two columns of photovoltaic modules within each associated group. The configuration structure includes: a switch S' is configured between the front end of the input switch of the numbered modules in the first column and the rear end of the input switch of the same numbered modules in the second column. n A switch S'' is configured between the rear end of the numbered input switch in the first column and the front end of the numbered input switch in the second column. n A switch S is configured between the front end of the last numbered output switch in the first column and the rear end of the last numbered output switch in the second column. ' N+1 A switch S is configured between the rear end of the last numbered output switch in the first column and the front end of the last numbered output switch in the second column. '' N+1 .

5. The system according to claim 4, characterized in that, The initial state of the switch includes: S n and S N+1 When S' is in the off state n and S' N+1 S'' is in the disconnected state. n and S'' N+1 It is in the disconnected state.

6. A shading reconstruction method for improving the output power of an SP structure photovoltaic array under local shading, using the control system described in any one of claims 1-5, characterized in that, include: The output voltage and output current of each photovoltaic module in the photovoltaic array are sampled in real time using the shadow detection module, and the power signal of each photovoltaic module is output after processing. The signal amplification module receives the power signal, amplifies it, and then transmits it to the DSP controller. The DSP controller determines whether each photovoltaic module is shaded based on the amplified power signal. When it is determined that there is a shaded photovoltaic module, the DSP controller generates the corresponding pulse width modulation (PWM) logic signal according to the shading reconstruction rule algorithm and sends it to the isolation circuit. The isolation circuit converts the pulse width modulation (PWM) logic signal into an optical signal or coded pulse for transmission, and the transmitted signal is restored to an electrical signal and sent to the drive circuit. The drive circuit controls the switching group to turn on and off according to the isolated electrical signal, so that the position of the photovoltaic module that is shaded is interchanged with that of the unshaded photovoltaic module, thereby realizing shadow reconstruction.

7. The method according to claim 6, characterized in that, The shadow reconstruction rules include: if there is no shadow shading, maintain the initial state of each switch; if in a certain association group, a photovoltaic module with number n in the second column is shaded while the photovoltaic module with the same number in the first column is not shaded, then disconnect the input switches S of the two photovoltaic modules with number n in the association group. n and the output switch S n+1 Simultaneously, close switch S' between the front end of the input / output switch of the first column n photovoltaic module and the rear end of the input / output switch of the second column n module. n and S' n+1 And the switch S'' between the rear end of the input / output switch of component n in the first column and the front end of the input / output switch of component n in the second column. n and S'' n+1 This allows the photovoltaic modules that are shaded to swap positions with unshaded photovoltaic modules of the same number in the associated group; if the shading disappears, the switch returns to its initial state.

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