A multi-operating mode stacked photovoltaic cell control system and method, computer program and computer readable storage medium

Abstract

The application discloses a kind of multi-work mode laminated photovoltaic cell control system and method, computer program and computer readable storage medium, the method is according to power ratio, illumination intensity, voltage stability, component temperature, power attenuation rate One or more parameters select the working mode of the switching laminated photovoltaic cell, the working mode at least includes first working mode and second working mode, the first working mode is configured to: the first sub-cell and second sub-cell of the laminated photovoltaic cell are independently executed MPPT algorithm respectively;The second working mode is configured to: the first sub-cell is executed MPPT algorithm, and the conversion output voltage of the first cell is with the conversion output voltage of the second sub-cell as reference voltage.By multi-parameter according to at least two working mode selection, effectively according to the change in working condition between multiple working modes, efficiency optimization and simplified control are considered, and operating cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power generation technology, and in particular to a multi-mode tandem photovoltaic cell control system and method, computer program, and computer-readable storage medium. Background Technology

[0002] In the field of photovoltaic power generation technology, due to the limitations of a single material in absorbing the wavelengths of the solar spectrum, the efficiency of single-junction photovoltaic cells has approached its theoretical value and is difficult to break through its bottleneck. However, tandem photovoltaic cells, by stacking materials with different band gaps, realize the segmented utilization of the solar spectrum, thereby making fuller use of the solar spectrum and becoming one of the main directions for the development of the next generation of photovoltaic cell industry.

[0003] Currently, the mainstream terminal architectures of tandem photovoltaic cells are divided into two-terminal (2T), three-terminal (3T), and four-terminal (4T). Considering the complexity of the manufacturing process, system cost, and photoelectric conversion efficiency, the four-terminal (4T) architecture has become the mainstream direction for the development of tandem photovoltaic cells due to its advantages such as electrical independence of sub-cells and no need for current matching constraints. In the 4T architecture, the MPP voltage (maximum power point voltage) of the two sub-cells differs significantly (e.g., about 35V~45V for crystalline silicon and about 70V~110V for perovskite), requiring two DC-DC converters to convert the voltage separately and then connect them in parallel for output.

[0004] Chinese patent document CN121263001A discloses a perovskite-crystalline silicon tandem solar cell, its electrical connection system, and method. For the perovskite top cell and the crystalline silicon bottom cell, it uses dual independent DC-DC converters and a maximum power point tracking (MPPT) control unit to monitor the current and voltage characteristics of the perovskite top cell and the crystalline silicon bottom cell in real time, calculate their respective maximum power, and adjust the voltage value corresponding to the maximum power value through their respective independent DC-DC converters. However, it only supports a single fixed operating mode, namely a dual-path forced independent full-time MPPT mode, and cannot flexibly adjust the MPPT control strategy according to dynamic factors such as light conditions, temperature changes, and component aging. Under the existing fixed mode architecture, even in low-light conditions such as early morning, evening, or partial shading where the output power of one sub-cell is extremely low, the system still needs to maintain full-power level dual-path high-frequency switching control and complex MPPT calculations. This not only leads to a sharp increase in the proportion of controller losses under low voltage and light load conditions, resulting in a significant decrease in overall system efficiency, but also makes it impossible to achieve intelligent strategy switching and dynamic coordination between "maximizing power output when there is sufficient light" and "simplifying control and reducing switching losses under low light / low power conditions," thus limiting the overall energy efficiency benefits of the system over a wide irradiance range. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-mode tandem photovoltaic cell control system and method, computer program and computer-readable storage medium, so as to realize the switching between multiple operating modes according to the changes in operating conditions, maximize power output when the light is sufficient and simplify power conversion control under weak light and low power conditions, thereby reducing operating costs.

[0006] To address the aforementioned technical problems, embodiments of the present invention provide a technical solution as follows: A multi-mode tandem photovoltaic cell control method, comprising: selecting and switching the operating mode of the tandem photovoltaic cell based on one or more parameters such as power ratio, illuminance, voltage stability, module temperature, and power degradation rate, wherein the operating mode includes at least a first operating mode and a second operating mode; the first operating mode is configured to: independently execute the MPPT algorithm on the first sub-cell and the second sub-cell of the tandem photovoltaic cell respectively; the second operating mode is configured to: execute the MPPT algorithm on the first sub-cell, wherein the conversion output voltage of the first sub-cell uses the conversion output voltage of the second sub-cell as a reference voltage.

[0007] Furthermore, the operating mode also includes a third operating mode, which is configured to: perform the MPPT algorithm on the second sub-cell, wherein the conversion output voltage of the second sub-cell is referenced to the conversion output voltage of the first sub-cell.

[0008] Furthermore, the method includes scoring the parameters of power ratio, light intensity, voltage stability, component temperature, and power attenuation rate, weighting and fusing the scores of each parameter to obtain a comprehensive decision score, and setting the mode switching trigger condition for the second or third working mode when the comprehensive decision score is greater than a preset comprehensive score switching threshold; setting the mode switching trigger condition for the first working mode when the power ratio is higher than the power ratio back-cut threshold.

[0009] Furthermore, when the duration of the mode switching trigger condition for the second or third working mode is greater than tc, and the interval between the previous working mode switch and th is greater than th, a mode switch is performed to switch the current working mode to the second or third working mode; when the duration of the mode switching trigger condition for the first working mode is greater than tc, and the interval between the previous working mode switch and th is greater than th, a mode switch is performed to switch the current second or third working mode to the first working mode; where tc is a preset confirmation time and th is a preset hold time.

[0010] Furthermore, the weighted weights for the power ratio, light intensity, voltage stability, component temperature, and power attenuation rate parameters are 0.35~0.45, 0.15~0.25, 0.10~0.20, 0.10~0.25, and 0.05~0.15, respectively.

[0011] Furthermore, it also includes reference voltage detection, and when the reference voltage exceeds a preset range, the tandem photovoltaic cell switches to a first operating mode.

[0012] Furthermore, a smooth transition control is adopted during the switching of the working mode, and the output voltage is changed to linearly transition from the current voltage to the target voltage with a preset slope.

[0013] Furthermore, it also includes the ability to select and switch working modes based on user-defined settings.

[0014] Furthermore, in the second or third operating mode, the sampling frequency of the reference voltage is ≥1kHz.

[0015] Furthermore, the MPPT algorithm employs dual closed-loop control. The inner loop is the output voltage loop, which uses a PI controller to control the deviation between the transformed output voltage and the reference voltage within ±1%. The outer loop is the power loop, which operates iteratively at a frequency of 1~10Hz based on the perturbation observation method or the incremental conductance method to continuously search for the maximum power point.

[0016] To address the aforementioned technical problems, this invention also provides a multi-mode tandem photovoltaic cell control system, comprising: a parameter acquisition unit for acquiring light intensity, module temperature, and voltage and current data corresponding to the first and second sub-cells, to obtain parameters such as power ratio, light intensity, voltage stability, module temperature, and power degradation rate; a working mode decision unit for selecting and switching working modes based on at least one of the aforementioned parameters; an MPPT control unit for executing the MPPT algorithm to control the DC-DC converter to perform voltage conversion and power output; and an output unit for connecting and outputting the converted power from the first and second sub-cells in parallel.

[0017] Furthermore, the operating modes include: a first operating mode in which the MPPT algorithm is executed independently on the first sub-battery and the second sub-battery by the MPPT control unit; a second mode in which the MPPT algorithm is executed on the first sub-battery by the MPPT control unit, and the conversion output voltage of the first sub-battery follows the conversion output voltage of the second sub-battery; and a third mode in which the MPPT algorithm is executed on the second sub-battery by the MPPT control unit, and the conversion output voltage of the second sub-battery follows the conversion output voltage of the first sub-battery.

[0018] To address the aforementioned technical problems, the present invention also provides a computer program, which, when executed by a computer processor, causes the computer to perform the method described in any of the preceding claims.

[0019] To address the aforementioned technical problems, the present invention also provides a computer-readable storage medium storing a computer program as described in claim 13, wherein the computer program, when executed by a processor, implements the method described in any of the preceding claims.

[0020] The multi-mode tandem photovoltaic cell control system and method, computer program, and computer-readable storage medium provided by this invention, compared with the prior art, select at least two operating modes based on multiple parameters such as power ratio, light intensity, voltage stability, module temperature, and power decay rate. This effectively switches between multiple operating modes according to changes in operating conditions, maximizing power output under sufficient sunlight while simplifying power conversion control under weak light and low power conditions, thus reducing operating costs. In particular, the hysteresis control strategy with preset confirmation and hold times avoids frequent jitter under critical conditions, improving system stability. Smooth transition control during mode switching further enhances system stability. Especially, during system operation, by detecting the reference voltage and switching the tandem photovoltaic cell to the first operating mode when the reference voltage exceeds a preset range, a safety mechanism is added. Furthermore, the MPPT algorithm dual closed-loop control accurately ensures that the output voltage of the sub-cell executing the MPPT algorithm follows the reference voltage, avoiding circulating current or power loss caused by voltage mismatch between the two paths. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the steps of the multi-mode stacked photovoltaic cell control method in an embodiment of the present invention; Figure 2 This is a schematic flowchart illustrating the steps of the multi-mode stacked photovoltaic cell control method in an embodiment of the present invention. Figure 3 This is a schematic diagram of the dual closed-loop control process of the MPPT algorithm in an embodiment of the present invention; Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the various embodiments of this invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the various embodiments of this invention to facilitate a better understanding of this application. However, the technical solutions claimed in the claims of this application can be implemented even without these technical details and with various variations and modifications based on the following embodiments.

[0023] One embodiment of the present invention relates to a multi-mode tandem photovoltaic cell control system, including a parameter acquisition unit, a working mode decision unit, an MPPT control unit, and an output unit. The tandem photovoltaic cell includes a first sub-cell and a second sub-cell. The parameter acquisition unit is used to collect data on light intensity, module temperature, and the voltage and current of the first and second sub-cells to obtain parameters such as power ratio, light intensity, voltage stability, module temperature, and power degradation rate. In one example, the system uses a sampling circuit to collect the input voltage and current of the two photovoltaic sources, namely the first and second sub-cells, in real time, calculates the real-time power to obtain the power ratio and voltage stability parameters; it uses sensors such as a illuminometer and a temperature sensor to collect light intensity and temperature data to obtain the light intensity and module temperature parameters; and it compares historical data with the current power to obtain the power degradation rate. The sampling period is preferably configured to be 1ms to 100ms. The operating mode decision unit is used to select and switch operating modes based on the parameters obtained above and user-defined settings. The execution of operating mode switching is based on at least one of the parameters. Preferably, the parameters are scored, then weighted and fused to obtain a comprehensive decision score, and then the operating mode is selected and switched based on the comprehensive decision score. The MPPT control unit is used to execute the MPPT algorithm, controlling the DC-DC converter to perform voltage conversion and power output. Depending on the operating mode, MPPT can selectively execute the MPPT algorithm on the first sub-cell and / or the second sub-cell. The output unit is used to connect the converted power from the first sub-cell and the second sub-cell in parallel for output. That is, in the corresponding operating mode, after the corresponding power conversion operation is performed by the first DC-DC converter corresponding to the first sub-cell and the second DC-DC converter corresponding to the second sub-cell, the positive and negative terminals of the two DC-DC outputs are connected together to form a unified DC output terminal to supply power to the subsequent inverter or load. By selecting at least two operating modes based on multiple parameters such as power ratio, light intensity, voltage stability, component temperature, and power attenuation rate, the system can effectively switch between multiple operating modes according to changes in operating conditions. This balances maximizing power output when there is sufficient light and simplifying power conversion control under low light and low power conditions, thereby reducing operating costs.

[0024] In one example, the operating mode decision unit in the multi-mode tandem photovoltaic cell control system can selectably switch between the following operating modes: a first operating mode, in which the MPPT control unit independently executes the MPPT algorithm on the first sub-cell and the second sub-cell respectively; a second mode, in which the MPPT control unit executes the MPPT algorithm on the first sub-cell, and the conversion output voltage of the first sub-cell follows the conversion output voltage of the second sub-cell; and a third mode, in which the MPPT control unit executes the MPPT algorithm on the second sub-cell, and the conversion output voltage of the second sub-cell follows the conversion output voltage of the first sub-cell. The first and second sub-cells can be any combination of the following: perovskite sub-cells and crystalline silicon sub-cells, photovoltaic modules with different orientations, photovoltaic modules with different technical routes, photovoltaic modules with different degradation rates, and photovoltaic modules with different specifications.

[0025] like Figure 1-3 As shown, one embodiment of the present invention relates to a multi-mode tandem photovoltaic cell control method, which can be applied to the above-mentioned system. After acquiring parameters such as power ratio, illuminance, voltage stability, module temperature, and power decay rate through a parameter acquisition unit, the operating mode of the tandem photovoltaic cell is selected and switched according to one or more of these parameters. The operating mode includes at least a first operating mode and a second operating mode. The first operating mode is configured to independently execute the MPPT algorithm on the first and second sub-cells of the tandem photovoltaic cell. The second operating mode is configured to execute the MPPT algorithm on the first sub-cell, with the conversion output voltage of the first sub-cell using the conversion output voltage of the second sub-cell as a reference voltage. Preferably, the operating mode further includes a third operating mode, which is configured to execute the MPPT algorithm on the second sub-cell, with the conversion output voltage of the second sub-cell using the conversion output voltage of the first sub-cell as a reference voltage. In any operating mode, when hot spot characteristics are detected, power limiting or bypass operation is performed on the DC-DC converter of the abnormal path, and maximum power point tracking is performed on the DC-DC converter corresponding to the normal path.

[0026] One embodiment relates to a multi-mode tandem photovoltaic cell control method, including scoring parameters such as power ratio, illuminance, voltage stability, module temperature, and power degradation rate; weighting and fusing the scores of each parameter to obtain a comprehensive decision score; and setting the comprehensive decision score greater than a preset comprehensive score switching threshold as a mode switching trigger condition for a second or third operating mode. In one example, the comprehensive score switching threshold is preset to 0.60~0.70, and the power ratio being higher than a power ratio cut-back threshold is set as a mode switching trigger condition for a first operating mode. In one example, the power ratio cut-back threshold is set to 20%~25%. In one example, the calculation steps for the comprehensive decision score include: first, scoring the parameters of power ratio, illuminance, voltage stability, component temperature, and power decay rate, with scoring functions represented as fp(R), fl(G), fv(V1,V2), ft(T), and fa(Px,Py), respectively, and the value range of each scoring function is [0, 1]. The weighting coefficients corresponding to the weighted fusion of the scores for power ratio, illuminance, voltage stability, component temperature, and power decay rate are represented as Wp, Wl, Wv, Wt, and Wa, respectively. The comprehensive decision score used for switching the second working mode is: S2 = Wpfp(R2) + Wlfl(G) + Wvfv(V1,V2) + Wtft(T) + Wafa(P1,P2); The comprehensive decision score used for switching the third working mode is: S3 = Wpfp(R1) + Wlfl(G) + Wvfv(V1,V2) + Wtft(T) + Wafa(P2,P1). Preferably, the power ratio is used as the primary decision condition, reflecting the real-time power contribution ratio of the two sub-cells, with a weighting coefficient Wp = 0.35~0.45; the light intensity is used to assist in determining whether the shading of weak light is temporary, with a weighting coefficient Wl = 0.15~0.25; the voltage stability reflects the MPPT tracking stability, and switching needs to be suppressed when the voltage fluctuation is large, with a weighting coefficient Wv = 0.10~0.20; the switching frequency needs to be limited when the component temperature is abnormal, with a weighting coefficient Wt = 0.10~0.25; and the power attenuation rate adopts long-term adaptive compensation to compensate for the power baseline offset, with a weighting coefficient Wa = 0.05~0.15. The scoring functions are defined as follows: fp(R) is the power ratio scoring function, where R is the power ratio of the sub-battery. The power ratio of the first sub-battery is R1 = P1 / (P1 + P2). The smaller R is, the larger the value of the scoring function fp(R). When R < θ_low, it takes the maximum value of 1.0, and when R > θ_high, it takes the minimum value of 0. θ_low is the power ratio switching threshold, and θ_high is the power ratio revert threshold. In one example, θ_low is set to 15%~20%, and θ_high is set to 20%~25%.fl(G) is the light intensity scoring function, where G is the ambient light intensity. When the light intensity is less than the preset lower threshold, the maximum value is 1.0, and the second or third mode is selected first to reduce the calculation frequency and switching loss of the MPPT algorithm. When the light intensity is greater than the preset upper threshold, the minimum value is 0. In one example, the preset lower threshold is 200W / m. 2 The preset upper limit threshold is 200W / m 2 G < 200 W / m 2 Take the higher value, G > 300W / m 2 The lower value is used. fv(V1,V2) is the voltage stability scoring function. When the voltage fluctuation is large, switching is suppressed. It takes the inverse normalized value of the standard deviation of the sliding window of the two voltages. When the voltage fluctuation exceeds the preset threshold, the mode switching sensitivity is reduced. ft(T) is the temperature scoring function, where T is the component temperature. In one example, the preset temperature range is -20℃ to 85℃. When the real-time detected temperature is within this range, a neutral value is taken. When it is outside the range, switching is suppressed to prioritize system stability and limit the mode switching frequency. fa(Px,Py) is the power decay rate scoring function, which compensates for power baseline drift and adjusts the score according to the difference in long-term power decay rates between the two channels. In order to automatically adapt to long-term operating factors such as component aging and seasonal light changes, and to avoid manual recalibration, the power ratio switching threshold θ_low is adaptively adjusted. The adaptive adjustment formula is θ'_low=θ_low(1- _aging), `_aging` represents the difference in degradation rate between the two sub-cells. By considering multiple parameters such as power ratio, light intensity, voltage stability, module temperature, and power degradation rate, at least two operating modes are selected. This effectively switches between multiple operating modes according to changes in operating conditions, maximizing power output under sufficient light and simplifying power conversion control under low light and low power conditions, thus reducing operating costs. In one example, the adaptive threshold adjustment mechanism is set to record the full power output of both sub-cells under clear weather conditions as a baseline after the initial system installation. The maximum power output is reassessed quarterly under clear weather conditions and compared with the baseline value to calculate the degradation rate of each sub-cell. Based on the difference in degradation rate, the power ratio switching threshold is dynamically adjusted. To prevent over-adaptive adjustment, the single threshold adjustment does not exceed ±5% of the original threshold, and the cumulative adjustment does not exceed ±30%. The adaptive adjustment of the power ratio switching threshold θ_low influences the overall decision score, optimizing the selection of the operating mode.

[0027] One embodiment relates to a multi-mode tandem photovoltaic cell control method, wherein the working mode switching determination conditions are as follows: when the duration of the mode switching trigger condition of the second or third working mode is greater than tc, and the interval time from the previous working mode switching is greater than th, a mode switch is performed, switching the current working mode to the second or third working mode; when the duration of the mode switching trigger condition of the first working mode is greater than tc, and the interval time from the previous working mode switching is greater than th, a mode switch is performed, switching the current second or third working mode to the first working mode; wherein tc is a preset confirmation time, and th is a preset hold time, preferably, tc is set to 30~120s, and th is set to 5~15min. In one example, switching from the current operating mode (e.g., mode 1) to mode 2 requires the following conditions to be met: the overall decision score S2 > θs and the duration > tc, and the time interval since the last operating mode switch > th, where θs is the preset overall score switching threshold, tc is the preset confirmation time, and th is the preset hold time. Switching back from mode 2 to mode 1 requires the following conditions to be met: R2 > θ_high and the duration > tc, and the time interval since the last operating mode switch > th. Switching from the current operating mode (e.g., mode 1) to mode 3 requires the following conditions to be met: the overall decision score S3 > θs and the duration > tc, and the time interval since the last operating mode switch > th. Switching back from mode 3 to mode 1 requires the following conditions to be met: R1 > θ_high and the duration > tc, and the time interval since the last operating mode switch > th. By using a hysteresis control strategy with preset confirmation and hold times, frequent jittering under critical conditions is avoided, which helps increase system stability.

[0028] One embodiment relates to a multi-mode tandem photovoltaic cell control method. To improve system reliability, it provides multiple safety mechanisms. When the tandem photovoltaic cell is in a second or third operating mode, a reference voltage is detected. If the reference voltage exceeds a preset range, the tandem photovoltaic cell switches to a first operating mode, replacing the reference voltage with a preset fixed voltage. When the DC-DC converter executing the MPPT algorithm fails, the circuit is automatically bypassed, and the system degrades to a single-circuit power supply mode. When external communication is interrupted, the last valid data is used for decision-making, and after a timeout, it switches to a preset default safety mode. When the program crashes or deadlocks, it automatically resets and starts up in the default safety mode.

[0029] One embodiment relates to a multi-mode tandem photovoltaic cell control method, wherein a smooth transition control is employed during the mode switching process, and the output voltage is linearly transitioned from the current voltage to the target voltage with a preset slope. In one example, during mode switching, the output voltage change rate of the DC-DC converter unit is controlled within a preset range, preferably not exceeding 10V / s, to achieve a smooth transition. During switching, the target voltage linearly transitions from the current voltage to the target voltage with a preset slope; during the transition, the power control loop temporarily reduces its bandwidth from the normal 1kHz to 100Hz to prioritize voltage stability; after the transition is completed, the normal MPPT control bandwidth is restored; during the transition, the output voltage fluctuation of the parallel bus output unit is controlled within ±5% of the rated value. The target voltage is either a reference voltage or a preset fixed voltage.

[0030] One embodiment relates to a multi-mode tandem photovoltaic cell control method, which further includes selecting and switching operating modes based on user-defined settings. The system receives user-defined operating mode preferences via a communication interface. These user-defined settings support three modes: a forced mode, which locks the specified operating mode and prevents switching; a priority mode, which uses the specified mode as much as possible but allows automatic switching; and an automatic mode, which selects and switches the operating mode of the tandem photovoltaic cell based on one or more parameters, including power ratio, light intensity, voltage stability, module temperature, and power degradation rate. The algorithm automatically makes the decision, and manual settings by the user override the automatic decision.

[0031] like Figure 3As shown, one embodiment relates to a multi-mode tandem photovoltaic cell control method. In the second or third operating mode, one sub-cell executes the MPPT algorithm, while the output voltage of the other sub-cell is converted to a reference voltage. The output voltage of the sub-cell executing the MPPT algorithm accurately follows the reference voltage, and the sampling frequency of the reference voltage is ≥1kHz. The MPPT algorithm employs dual closed-loop control. The inner loop is the output voltage loop, which uses a PI controller to control the deviation between the converted output voltage and the reference voltage within ±1%. The outer loop is the power loop, which operates iteratively at a frequency of 1~10Hz based on the perturbation and observation (P&O) method or the incremental conductance method, continuously searching for the maximum power point. In one example, the inner loop, based on a PI controller, is responsible for the rapid and high-precision adjustment of the output voltage. Its bandwidth is designed to be 1~10kHz to ensure rapid tracking capability of the reference voltage, with an adjustment time of less than 100ms and excellent dynamic response. The outer loop operates at a low-frequency iteration of 1~10Hz based on classic MPPT algorithms such as the perturbation and observation (P&O) method or the incremental conductance method (InC). The outer loop continuously searches for and approaches the maximum power point by slowly adjusting the voltage reference value of the inner loop without interfering with the dynamic performance of the inner loop. The inner loop controls the steady-state error of the output voltage within ±1%, meeting the voltage matching requirements for parallel bus connections and effectively suppressing circulating current generation. The PI controller parameters are designed with engineering stability margins, ensuring a system phase margin ≥45° and a gain margin ≥6dB, ensuring robustness under all operating conditions.

[0032] One embodiment relates to a computer program that, when executed by a computer processor, causes the computer to perform the methods described in the above embodiments.

[0033] One embodiment relates to a computer-readable storage medium storing a computer program as described above, which, when executed by a processor, enables the computer to perform the methods described in the above embodiment.

[0034] In one application example, the tandem photovoltaic system initially operates in the first working mode, where the power ratio switching threshold θ_low is 15%, the power ratio cut-back threshold θ_high is 20%, the preset confirmation time tc is 60 seconds, and the preset hold time th is 5 minutes. The first sub-cell is a crystalline silicon cell, and the second sub-cell is a perovskite cell. The input power of the crystalline silicon sub-cell is approximately 400W, and the input power of the perovskite sub-cell is approximately 200W. Due to cloud cover, the power of the perovskite circuit gradually decreases to approximately 50W within 2 minutes. At this point, the power ratio of the second sub-cell, R2 = 50 / (400+50) = 11.11%, and remains below 15% for more than 60 seconds. Simultaneously, the light intensity sensor displays a current light intensity of 180W / m², below the preset lower limit threshold of 200W / m², with normal temperature and stable voltage. The multi-condition weighted decision algorithm in step S2 calculates S2 = 0.78, exceeding the preset comprehensive score switching threshold of 0.65, thus determining that the conditions for switching to the second mode are met, and triggering the switch. Switching Process: Using the 88V output voltage corresponding to the perovskite sub-cell as the reference voltage, the crystalline silicon sub-cell executes the MPPT algorithm. Boost first smoothly transitions the output voltage from 60V to 88V at a slope of 10V / s. During the transition, the power loop bandwidth decreases from 1kHz to 100Hz. After the transition is complete, dual closed-loop control is activated. The inner loop maintains 88V, while the outer loop searches for the maximum power point (MPP) of the crystalline silicon sub-cell. The total system power is approximately 450W, with the perovskite path contributing approximately 50W and the crystalline silicon path contributing approximately 400W. After approximately 10 minutes, the clouds disperse, and the perovskite path power recovers to approximately 180W, i.e., R²=31.03%. The illuminance recovers to 650W / m², continuously exceeding the power ratio cut-back threshold of 20% and maintaining this level for more than 60 seconds. The cut-back condition is met, and the system switches back to the first mode.

[0035] In one application example, the tandem photovoltaic system operates in the second working mode, where the power ratio switching threshold θ_low is 15%, the power ratio cut-back threshold θ_high is 20%, the preset confirmation time tc is 60 seconds, the preset hold time th is 5 minutes, and the preset reference voltage range is 70V~95V. The first sub-cell is a crystalline silicon cell, and the second sub-cell is a perovskite cell. Due to poor connector contact, the output voltage of the perovskite sub-cell experiences intermittent open circuits, causing the reference voltage to abruptly change from approximately 88V to approximately 100V, exceeding the preset reference voltage range. This triggers the safety mechanism, and the system automatically switches to the first mode, replacing the reference voltage with a preset fixed voltage of 60V. The crystalline silicon and perovskite sub-cells independently perform MPPT (Multi-Processing Test). Simultaneously, a fault alarm is reported via the communication interface. Once the perovskite sub-cell connection is restored, the fault is resolved, and the system returns to the second mode. The entire fault handling process is completed within 500ms, and external power supply remains uninterrupted.

[0036] In one application example, after one year of operation, a quarterly assessment of the tandem photovoltaic system revealed a power degradation of approximately 3% in the crystalline silicon sub-cells, decreasing from a 400W baseline to 388W, and approximately 8% in the perovskite sub-cells, decreasing from a 200W baseline to 184W. The difference in degradation rates between the two sub-cells is significant. With _aging=5%, the power ratio switching threshold of the crystalline silicon sub-cells is automatically adjusted from 15% to 15%(1-0.05)=14.25 based on the adaptive threshold adjustment mechanism to compensate for the systematically low power of the perovskite sub-cells. The adjustment range of 0.75 percentage points is within ±5% of the original threshold, which complies with safety limits. After the adjustment, the system's mode switching behavior under the same illumination conditions remains consistent with the initial state.

[0037] In one application example, the control method of this invention can be deployed in any of the following hardware configurations: an independently deployed four-terminal intelligent controller with a complete control algorithm built into an MCU / DSP; an embedded controller, such as an ARM Cortex-M4, integrated into the photovoltaic module junction box; a DSP / ARM control module built into the photovoltaic inverter as part of the inverter firmware; a cloud controller that remotely executes the control algorithm via a 4G / 5G / WiFi communication network, sending control commands to field actuators, with the cloud server running a complete multi-condition decision model; a distributed edge computing node deployed on a local server in the photovoltaic power station, communicating with multiple intelligent controllers via a local area network; or a hybrid deployment mode where the local controller runs a real-time control loop, and the cloud server runs decision algorithms and data analysis, with both synchronizing via MQTT or HTTP protocols.

[0038] In one application example, the weighting coefficients for parameters such as power ratio, illuminance, voltage stability, component temperature, and power attenuation rate are configured differently for different scenarios. The standard configuration is Wp=0.40, Wl=0.20, Wv=0.15, Wt=0.15, Wa=0.10; the configuration for cloudy areas is Wp=0.35, Wl=0.25, Wv=0.15, Wt=0.15, Wa=0.10; the configuration for high-temperature areas is Wp=0.35, Wl=0.15, Wv=0.15, Wt=0.25, Wa=0.10; and the configuration for old power plants is Wp=0.35, Wl=0.15, Wv=0.15, Wt=0.10, Wa=0.15.

[0039] The multi-mode tandem photovoltaic cell control system and method, computer program, and computer-readable storage medium provided by this invention select at least two operating modes based on multiple parameters such as power ratio, light intensity, voltage stability, module temperature, and power degradation rate. This effectively switches between multiple operating modes according to changes in operating conditions, maximizing power output under sufficient sunlight while simplifying power conversion control under low light and low power conditions, thus reducing operating costs. In particular, the hysteresis control strategy with preset confirmation and hold times avoids frequent fluctuations under critical conditions, improving system stability. Smooth transition control during mode switching further enhances system stability. Especially, during system operation, reference voltage detection switches the tandem photovoltaic cell to the first operating mode when the reference voltage exceeds a preset range, adding a safety mechanism. Furthermore, the MPPT algorithm dual closed-loop control accurately tracks the sub-cell conversion output voltage to the reference voltage, preventing circulating current or power loss caused by voltage mismatch.

[0040] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be defined by the claims.

Claims

1. A method for controlling multi-mode tandem photovoltaic cells, characterized in that, include: The operating mode of the tandem photovoltaic cell is selected and switched according to one or more parameters such as power ratio, light intensity, voltage stability, module temperature, and power decay rate. The operating mode includes at least a first operating mode and a second operating mode. The first operating mode is configured to execute the MPPT algorithm independently on the first sub-cell and the second sub-cell of the tandem photovoltaic cell respectively. The second operating mode is configured to execute the MPPT algorithm on the first sub-cell, and the transformation output voltage of the first sub-cell is referenced by the transformation output voltage of the second sub-cell.

2. The multi-mode tandem photovoltaic cell control method according to claim 1, characterized in that, The operating mode also includes a third operating mode, which is configured to: perform the MPPT algorithm on the second sub-cell, and the conversion output voltage of the second sub-cell is referenced to the conversion output voltage of the first sub-cell.

3. The multi-mode tandem photovoltaic cell control method according to claim 1 or 2, characterized in that, This includes scoring the parameters such as power ratio, light intensity, voltage stability, component temperature, and power attenuation rate, weighting and fusing the scores of each parameter to obtain a comprehensive decision score, and setting the mode switching trigger condition for the second or third working mode when the comprehensive decision score is greater than a preset comprehensive score switching threshold; setting the mode switching trigger condition for the first working mode when the power ratio is higher than the power ratio back-cut threshold.

4. The multi-mode tandem photovoltaic cell control method according to claim 3, characterized in that, This includes performing a mode switch when the duration of the mode switching trigger condition for the second or third working mode is greater than tc, and the interval between the current mode switch and the previous mode switch is greater than th, thereby switching the current working mode to the second or third working mode; and performing a mode switch when the duration of the mode switching trigger condition for the first working mode is greater than tc, and the interval between the current mode switch and the previous mode switch is greater than th, thereby switching the current second or third working mode to the first working mode; where tc is a preset confirmation time and th is a preset hold time.

5. The multi-mode tandem photovoltaic cell control method according to claim 3, characterized in that, The weighted weights for the power ratio, light intensity, voltage stability, component temperature, and power attenuation rate parameters are 0.35~0.45, 0.15~0.25, 0.10~0.20, 0.10~0.25, and 0.05~0.15, respectively.

6. The multi-mode tandem photovoltaic cell control method according to claim 1 or 2, characterized in that, It also includes reference voltage detection, and when the reference voltage exceeds a preset range, the tandem photovoltaic cell switches to the first working mode.

7. The multi-mode tandem photovoltaic cell control method according to claim 1 or 2, characterized in that, The working mode switching process adopts smooth transition control, and the output voltage is changed linearly from the current voltage to the target voltage with a preset slope.

8. The multi-mode tandem photovoltaic cell control method according to claim 1 or 2, characterized in that, It also includes the ability to select and switch working modes based on user-defined settings.

9. The multi-mode tandem photovoltaic cell control method according to claim 1 or 2, characterized in that, In the second or third operating mode, the sampling frequency of the reference voltage is ≥1kHz.

10. The multi-mode tandem photovoltaic cell control method according to claim 9, characterized in that, The MPPT algorithm employs dual closed-loop control. The inner loop is the output voltage loop, which uses a PI controller to control the deviation between the transformed output voltage and the reference voltage within ±1%. The outer loop is the power loop, which operates iteratively at a frequency of 1~10Hz based on the perturbation observation method or the incremental conductance method to continuously search for the maximum power point.

11. A multi-mode tandem photovoltaic cell control system, characterized in that, include: The parameter acquisition unit is used to collect light intensity, module temperature, and voltage and current data corresponding to the first and second sub-cells to obtain parameters such as power ratio, light intensity, voltage stability, module temperature, and power decay rate. The working mode decision unit is used to select and switch the working mode based on at least one of the above parameters. The MPPT control unit is used to execute the MPPT algorithm and control the DC-DC converter to perform voltage conversion and power output. The output unit connects and outputs the power converted from the first and second sub-cells in parallel.

12. The multi-mode tandem photovoltaic cell control system according to claim 11, characterized in that, The working modes include: In the first operating mode, the MPPT algorithm is executed independently on the first sub-battery and the second sub-battery by the MPPT control unit. In the second mode, the MPPT algorithm is executed on the first sub-battery through the MPPT control unit, and the conversion output voltage of the first sub-battery follows the conversion output voltage of the second sub-battery. In the third mode, the MPPT algorithm is executed on the second sub-battery through the MPPT control unit, and the conversion output voltage of the second sub-battery follows the conversion output voltage of the first sub-battery.

13. A computer program, characterized in that, When the program is executed by a computer processor, the computer performs the method as described in any one of claims 1-10.

14. A computer-readable storage medium, characterized in that, The computer program as described in claim 13 is stored thereon, and when executed by a processor, the computer program implements the method as described in any one of claims 1-10.

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