Mode control method and device, medium and equipment

Abstract

The invention discloses a mode control method, a mode control device, a medium and equipment, and provides double control modes including a first control mode and a second control mode, when a photovoltaic output voltage is relatively high, the first control mode is adopted, a direct-current booster circuit is in a straight-through mode and has no boosting function, so that unnecessary switching loss is avoided, and the switching efficiency is improved. The electric energy conversion efficiency of the photovoltaic inverter is improved, and maximum power point tracking and inversion grid connection are carried out on the alternating current side; and when the photovoltaic output voltage is low, a second control mode is adopted, the DC side carries out maximum power point tracking and necessary boost operation, and the AC side carries out inversion grid connection. Compared with a traditional single control mode, no matter whether photovoltaic energy is sufficient or not, the system can work at the optimal efficiency point all the time, the step-up link can be optimized for the situation that the photovoltaic energy is sufficient, and therefore the electric energy conversion efficiency of the photovoltaic inverter is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power generation, and in particular to a mode control method, device, medium and equipment. Background Art

[0002] Generally, a photovoltaic inverter only adopts one control mode, that is, the maximum power point tracking (MPPT) and boost of the photovoltaic output voltage are realized on the DC side of the photovoltaic inverter, and the inversion and grid connection are realized on the AC side of the photovoltaic inverter.

[0003] However, this control mode is not flexible enough. For example, when the photovoltaic energy is sufficient, the photovoltaic output voltage is relatively large at this time and is sufficient for inversion without boosting at all. If the above single control mode is still adopted at this time, it will increase unnecessary switching losses and reduce the overall power conversion efficiency of the inverter. Summary of the Invention

[0004] Based on this, it is necessary to provide a mode control method, device, medium and equipment to solve the problem that in the prior art, under different photovoltaic voltage conditions, the traditional single control mode is still adopted, which may increase unnecessary switching losses and reduce the overall power conversion efficiency of the inverter.

[0005] In a first aspect, an embodiment of the present application provides a mode control method applied to a photovoltaic inverter, where the photovoltaic inverter includes a DC side and an AC side, and the method includes:

[0006] Obtain the current photovoltaic output voltage and the target bus voltage of the input object;

[0007] If the photovoltaic output voltage is greater than the target bus voltage, adjust the photovoltaic output voltage through a first control mode; wherein, in the first control mode, the DC side is in a direct-through state, and the maximum power point tracking and inversion grid connection are performed through the AC side;

[0008] If the photovoltaic output voltage is less than or equal to the target bus voltage, adjust the photovoltaic output voltage through a second control mode; wherein, in the second control mode, the maximum power point tracking and boost are performed through the DC side, and the inversion grid connection is performed through the AC side.

[0009] In some embodiments of the present application, the step of if the photovoltaic output voltage is greater than the target bus voltage, adjust the photovoltaic output voltage through a first control mode includes:

[0010] If the photovoltaic output voltage is greater than the target bus voltage, control the photovoltaic output voltage to continuously perturb in a decreasing direction in the first control mode;

[0011] If the photovoltaic output voltage tracks the maximum power point voltage during the perturbation process and the maximum power point voltage is greater than the target bus voltage, then control the input object to operate at the maximum power point voltage.

[0012] In some embodiments of the present application, if the photovoltaic output voltage is greater than the target bus voltage, then adjusting the photovoltaic output voltage through the first control mode includes:

[0013] If the photovoltaic output voltage is greater than the target bus voltage, then control the photovoltaic output voltage to continuously perturb in a decreasing direction under the first control mode;

[0014] When the photovoltaic output voltage is less than or equal to the target bus voltage during the perturbation process, switch from the first control mode to the second control mode to adjust the photovoltaic output voltage until the maximum power point voltage is tracked;

[0015] Control the input object to operate at the maximum power point voltage.

[0016] In some embodiments of the present application, if the photovoltaic output voltage is less than or equal to the target bus voltage, then adjusting the photovoltaic output voltage through the second control mode includes:

[0017] If the photovoltaic output voltage is less than or equal to the target bus voltage, then control the photovoltaic output voltage to continuously perturb in an increasing direction under the second control mode;

[0018] If the photovoltaic output voltage tracks the maximum power point voltage during the perturbation process and the maximum power point voltage is less than or equal to the target bus voltage, then control the input object to operate at the maximum power point voltage.

[0019] In some embodiments of the present application, if the photovoltaic output voltage is less than or equal to the target bus voltage, then adjusting the photovoltaic output voltage through the second control mode includes:

[0020] If the photovoltaic output voltage is less than or equal to the target bus voltage, then control the photovoltaic output voltage to continuously perturb in an increasing direction under the second control mode;

[0021] When the photovoltaic output voltage is greater than the target bus voltage during the perturbation process, switch from the second control mode to the first control mode to adjust the photovoltaic output voltage until the maximum power point voltage is tracked;

[0022] Control the input object to operate at the maximum power point voltage.

[0023] In some embodiments of the present application, the target bus voltage includes a first bus voltage and a second bus voltage, the first bus voltage is greater than the second bus voltage, and if the photovoltaic output voltage is greater than the target bus voltage, adjusting the photovoltaic output voltage through a first control mode includes:

[0024] If the photovoltaic output voltage is greater than the first bus voltage, adjusting the photovoltaic output voltage through the first control mode;

[0025] After adjusting the photovoltaic output voltage through the first control mode, if the photovoltaic output voltage is less than or equal to the first bus voltage and greater than or equal to the second bus voltage, maintaining the adjustment of the photovoltaic output voltage by the first control mode;

[0026] If the photovoltaic output voltage is less than the second bus voltage, switching from the first control mode to the second control mode to adjust the photovoltaic output voltage.

[0027] In some embodiments of the present application, the target bus voltage includes a first bus voltage and a second bus voltage, the first bus voltage is greater than the second bus voltage, and if the photovoltaic output voltage is less than or equal to the target bus voltage, adjusting the photovoltaic output voltage through a second control mode includes:

[0028] If the photovoltaic output voltage is less than the second bus voltage, adjusting the photovoltaic output voltage through the second control mode;

[0029] After adjusting the photovoltaic output voltage through the second control mode, if the photovoltaic output voltage is less than or equal to the first bus voltage and greater than or equal to the second bus voltage, maintaining the adjustment of the photovoltaic output voltage by the second control mode;

[0030] If the photovoltaic output voltage is greater than the first bus voltage, switching from the second control mode to the first control mode to adjust the photovoltaic output voltage.

[0031] In a second aspect, an embodiment of the present application further provides a mode control device applied to a photovoltaic inverter. The photovoltaic inverter includes a DC side and an AC side. The mode control device includes:

[0032] A parameter acquisition module for acquiring the current photovoltaic output voltage and the target bus voltage of the input object;

[0033] The first control module is configured to adjust the photovoltaic output voltage through a first control mode if the photovoltaic output voltage is greater than the target bus voltage; wherein, in the first control mode, the DC side is in a direct-through state, and the maximum power point tracking and inversion grid connection are performed through the AC side.

[0034] The second control module is configured to adjust the photovoltaic output voltage through a second control mode if the photovoltaic output voltage is less than or equal to the target bus voltage; wherein, in the second control mode, the maximum power point tracking and boosting are performed through the DC side, and the inversion grid connection is performed through the AC side.

[0035] In a third aspect, an embodiment of the present application further provides a terminal device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is executed by the processor, the steps in the above-mentioned mode control method are implemented.

[0036] In a fourth aspect, an embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by the processor, the steps in the above-mentioned mode control method are implemented.

[0037] In a fifth aspect, an embodiment of the present application further provides a computer program product or a computer program, which includes computer instructions stored in a computer-readable storage medium. The processor of the computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device executes the methods provided in the various alternative implementation manners of the embodiments of the present application.

[0038] The present invention provides a mode control method, device, medium and device, which provides a dual control mode, including a first control mode and a second control mode, and can automatically select the optimal control mode according to the relationship between the photovoltaic output voltage and the target bus voltage. When the photovoltaic output voltage is high, the first control mode is adopted, and the DC boost circuit is in a direct-through mode without a boost function, avoiding unnecessary switching losses and improving the power conversion efficiency of the photovoltaic inverter. Then, the maximum power point tracking and inversion grid connection are performed through the AC side. When the photovoltaic output voltage is low, the second control mode is adopted, the maximum power point tracking and necessary boosting operations are performed on the DC side, and the inversion grid connection is performed on the AC side. Compared with the traditional single control mode, the present invention can make the system always work at the optimal efficiency point regardless of whether the photovoltaic energy is sufficient, and for the case of sufficient photovoltaic energy, the boosting link can be optimized, thereby improving the power conversion efficiency of the photovoltaic inverter. Description of the Drawings

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0040] Wherein:

[0041] Figure 1 It is a schematic flowchart of the mode control method provided by the embodiment of the present application;

[0042] Figure 2 It is a voltage-power curve graph under a certain light condition and an external environment of 25°C;

[0043] Figure 3 It is a voltage-power curve graph under a certain light condition and an external environment of 35°C;

[0044] Figure 4 It is a voltage-power curve graph combined with hysteresis logic;

[0045] Figure 5 It is a schematic structural diagram of the mode control device;

[0046] Figure 6 It is a structural block diagram of the terminal device. Detailed implementation manners

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0048] The terms "first", "second", etc. in the specification and claims of the present application and the above accompanying drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products or devices.

[0049] References herein to "embodiments" mean that the particular features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0050] Please refer to Figure 1 , Figure 1 which is a schematic flowchart of the mode control method provided by an embodiment of the present application. Although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown in the drawings. The mode control method provided by the embodiments of the present application is applied to a photovoltaic inverter, and the photovoltaic inverter includes a DC side and an AC side. This method realizes effective adjustment of the photovoltaic output voltage and improves the working efficiency of the photovoltaic inverter by selecting different control modes according to the magnitude relationship between the photovoltaic output voltage and the target bus voltage.

[0051] Specifically, the specific process of the mode control method of the embodiments of the present application is as follows:

[0052] S101, Obtain the current photovoltaic output voltage and the target bus voltage of the input object.

[0053] Among them, the input object of the photovoltaic inverter can be a photovoltaic module or a photovoltaic array, etc. The DC electrical energy output by it is converted into AC electrical energy by the photovoltaic inverter and then incorporated into the grid. The photovoltaic inverter includes a DC side and an AC side. The DC side is used to receive and process the DC electrical energy output by the photovoltaic module, and the AC side is used to convert the processed electrical energy into AC electrical energy and grid-connect it.

[0054] Among them, the photovoltaic output voltage is the voltage value currently output by the input object, which can be collected by a voltage sensor arranged at the input end of the photovoltaic inverter. The collection can be carried out at equal time intervals (for example, once every 10 minutes, or once every half hour), or data collection can be carried out when the user actively inputs a collection instruction or the cloud issues a collection instruction. The target bus voltage is a reference voltage value preset by the system and is used to determine which control mode should be adopted subsequently. Optionally, the target bus voltage can be the nominal bus voltage, that is, the bus voltage required under normal grid-connection conditions, such as 220V, 380V, etc.

[0055] Next, different control modes are selected according to the magnitude relationship between the photovoltaic output voltage and the target bus voltage.

[0056] S102, If the photovoltaic output voltage is greater than the target bus voltage, adjust the photovoltaic output voltage through the first control mode.

[0057] Among them, in the first control mode, the DC side is in a direct connection state, and the maximum power point tracking and inverter grid connection are carried out through the AC side. Among them, the output power of the photovoltaic cell is related to the output voltage and current, and its output characteristic curve (P-V curve) shows a single-peak characteristic. On this curve, there is a point at which the power output by the photovoltaic cell reaches the maximum value, and this point is called the maximum power point. Maximum power point tracking refers to the process of dynamically adjusting the working voltage and / or working current of the input object through an algorithm to make the input object continuously operate near the maximum power point. Inverter grid connection refers to the process of converting the direct current output by the input object into alternating current that meets the grid requirements through the AC side of the inverter and connecting it to the grid.

[0058] When the photovoltaic output voltage is greater than the target bus voltage, the first control mode is adopted. In the first control mode, the DC side is in a direct connection state, that is, no boost operation is performed, and the voltage output by the photovoltaic module is directly transmitted to the AC side. At this time, by adjusting the equivalent impedance in the inverter circuit on the AC side, the maximum power point tracking is realized on the AC side, and the inverter grid connection operation is completed on the AC side at the same time. This mode is applicable to the situation of high light intensity and high photovoltaic output voltage, which can reduce the power conversion link and improve the system efficiency.

[0059] S103, if the photovoltaic output voltage is less than or equal to the target bus voltage, the photovoltaic output voltage is adjusted through the second control mode.

[0060] Among them, in the second control mode, the maximum power point tracking and boosting are carried out through the DC side, and the inverter grid connection is carried out through the AC side.

[0061] When the photovoltaic output voltage is less than or equal to the target bus voltage, the second control mode is adopted. In the second control mode, the DC side is no longer in a direct connection state. First, the maximum power point tracking is realized by adjusting the equivalent impedance in the DC side boost circuit, and then the boost process is carried out to boost the photovoltaic output voltage to a voltage level suitable for the operation of the AC side, and then the inverter grid connection operation is completed by the AC side. This mode is applicable to the situation of low light intensity and low photovoltaic output voltage. Through the boost operation on the DC side, it is ensured that the system can work normally.

[0062] The above embodiments provide a dual control mode, including a first control mode and a second control mode, which can automatically select the optimal control mode according to the relationship between the photovoltaic output voltage and the target bus voltage. When the photovoltaic output voltage is high, the first control mode is adopted, and the DC boost circuit is in a through mode without boost function, avoiding unnecessary switching losses and improving the power conversion efficiency of the photovoltaic inverter. Then, the maximum power point tracking and inversion grid connection are carried out on the AC side. When the photovoltaic output voltage is low, the second control mode is adopted, and the maximum power point tracking and necessary boost operation are carried out on the DC side, and the inversion grid connection is carried out on the AC side. Compared with the traditional single control mode, in these embodiments, regardless of whether the photovoltaic energy is sufficient, the system can always operate at the optimal efficiency point, and for the case of sufficient photovoltaic energy, the boost link can be optimized, thereby improving the power conversion efficiency of the photovoltaic inverter.

[0063] It can be understood that the target bus voltage in the above embodiments is relatively fixed, but the current photovoltaic characteristic curve and photovoltaic output voltage of the input object will change continuously with external environmental factors such as temperature and light intensity. Therefore, it is necessary to continuously perform maximum power point tracking, which will affect how to specifically execute the first control mode and the second control mode subsequently. Exemplarily, as Figure 2 shown, Figure 2 is a voltage-power curve graph under a certain light condition and an external environment of 25°C, where the maximum power point voltage (the voltage corresponding to point P2) in this scenario is greater than the target bus voltage (the voltage corresponding to point P1).

[0064] For Figure 2 the application scenario, in some embodiments of the present application, if the photovoltaic output voltage is greater than the target bus voltage in S102, the photovoltaic output voltage is adjusted through the first control mode, including:

[0065] S102a, if the photovoltaic output voltage is greater than the target bus voltage, then control the photovoltaic output voltage to continuously perturb in a decreasing direction in the first control mode.

[0066] S102b, if the maximum power point voltage is tracked during the perturbation of the photovoltaic output voltage and the maximum power point voltage is greater than the target bus voltage, then control the input object to operate at the maximum power point voltage.

[0067] Among them, continuously disturbing the photovoltaic output voltage in the decreasing direction means continuously applying a negative voltage change amount to the photovoltaic output voltage. After each disturbance is applied, immediately monitor the change in the photovoltaic output power. If the power after the disturbance is greater than the power before the disturbance, it indicates that the current disturbance in the voltage decreasing direction is correct, and continue to perform the next disturbance in the same direction until the power after the disturbance is less than the power before the disturbance. On the contrary, continuously disturbing the photovoltaic output voltage in the increasing direction means continuously applying a positive voltage change amount to the photovoltaic output voltage. After each disturbance is applied, immediately monitor the change in the photovoltaic output power. If the power after the disturbance is greater than the power before the disturbance, it indicates that the current disturbance in the voltage increasing direction is correct, and continue to perform the next disturbance in the same direction until the power after the disturbance is less than the power before the disturbance.

[0068] For example, if the currently obtained photovoltaic output voltage is greater than 700V and at this time the photovoltaic output voltage is greater than the target bus voltage, then in the first control mode, control the photovoltaic output voltage to continuously disturb in the decreasing (from right to left) direction.

[0069] Exemplarily, the maximum power point can be found by the method of disturbing and observing the photovoltaic output voltage. First, control the photovoltaic output voltage to be disturbed in the decreasing direction, that is, gradually reduce the photovoltaic output voltage while monitoring the change in the photovoltaic output power. According to the characteristic curve of the photovoltaic module, when the voltage changes from the open-circuit voltage to the maximum power point voltage, the output power will gradually increase; when the voltage is lower than the maximum power point voltage, the output power will start to decrease. By comparing the change in the output power before and after each disturbance, the relative position of the current operating point and the maximum power point can be judged, and the disturbance direction can be adjusted accordingly. When the system detects that the photovoltaic output power starts to decrease, it indicates that the maximum power point has been passed. At this time, record the corresponding voltage value as the maximum power point voltage. If this maximum power point voltage is still greater than the target bus voltage, then maintain the first control mode and control the input object to operate stably at this maximum power point voltage to achieve maximum power output.

[0070] Alternatively, the variable step-size perturbation observation method can be used to find the maximum power point. First, control the photovoltaic output voltage to be perturbed in the decreasing direction with a large step size to quickly approach the maximum power point region. When it is detected that the output power change rate begins to decrease, the system automatically reduces the perturbation step size to more accurately locate the maximum power point. The system determines the relative position between the current operating point and the maximum power point by calculating the ratio of the power change amount to the voltage change amount (dP / dV) before and after each perturbation. When dP / dV changes from a positive value to a negative value, it indicates that the maximum power point has been passed, and the corresponding voltage value at this time is recorded as the maximum power point voltage. If the maximum power point voltage is still greater than the target bus voltage, the first control mode is maintained, and the input object is controlled to operate stably at this maximum power point voltage. To cope with the change in light intensity, the system will periodically perform small perturbations to detect whether the maximum power point has changed. If a new maximum power point is detected, the system will timely adjust the operating point to ensure that it always operates at the maximum power point.

[0071] Through the gradual adjustment of the above first control mode, the system can quickly operate at the optimal efficiency point in this scenario.

[0072] For Figure 2 the application scenario, in some embodiments of the present application, if the photovoltaic output voltage is less than or equal to the target bus voltage in S103, the photovoltaic output voltage is adjusted through the second control mode, including:

[0073] S103a, if the photovoltaic output voltage is less than or equal to the target bus voltage, then control the photovoltaic output voltage to be continuously perturbed in the increasing direction in the second control mode.

[0074] S103b, when the photovoltaic output voltage is greater than the target bus voltage during the perturbation process, switch from the second control mode to the first control mode to adjust the photovoltaic output voltage until the maximum power point voltage is tracked.

[0075] S103c, control the input object to operate at the maximum power point voltage.

[0076] For example, if the currently obtained photovoltaic output voltage is less than 300V and less than the target bus voltage, then control the photovoltaic output voltage to be continuously perturbed in the increasing direction (from left to right in the figure) in the second control mode.

[0077] Similarly, the system can use the perturbation observation method or the variable step-size perturbation observation method to find the maximum power point. First, control the photovoltaic output voltage to be perturbed in the increasing direction, that is, gradually increase the photovoltaic output voltage, and at the same time monitor the change in the photovoltaic output power. According to the characteristic curve of the photovoltaic module, when the voltage changes in the direction of the maximum power point voltage, the output power will gradually increase.

[0078] When the photovoltaic output voltage rises above the target bus voltage, the system triggers a control mode switching mechanism to switch from the second control mode to the first control mode. During the switching process, a smooth transition strategy is adopted, substituting the parameters currently used in the second control mode into the first control mode to avoid system fluctuations. In the first control mode, the DC side switches to a direct-through state, and the AC side starts to undertake the functions of maximum power point tracking and inverter grid connection, continuously adjusting the photovoltaic output voltage until the maximum power point voltage is found.

[0079] In some embodiments of the present application, the system also adopts a multi-sampling confirmation mechanism to ensure the reliability of the switching conditions. In addition, the system will predict the possible position of the maximum power point according to the change trend of the light intensity, accelerating the process of finding the maximum power point.

[0080] Through the improved control mode switching mechanism described above, the system can more flexibly respond to changes in light intensity and load, ensuring efficient operation under various working conditions. At the same time, the smooth transition strategy and the multi-sampling confirmation mechanism improve the stability and reliability of the system, reducing energy losses caused by mis-switching.

[0081] In another scenario, for example, as Figure 3 shown, Figure 3 is the voltage-power curve graph under certain light conditions and an external environment temperature of 35°C. In this scenario, the maximum power point voltage (the voltage corresponding to point P3) is less than the target bus voltage (the voltage corresponding to point P4).

[0082] For Figure 3 the application scenario, in some embodiments of the present application, in S102, if the photovoltaic output voltage is greater than the target bus voltage, the photovoltaic output voltage is adjusted through the first control mode, including:

[0083] S102c, if the photovoltaic output voltage is greater than the target bus voltage, then in the first control mode, control the photovoltaic output voltage to continuously perturb in a decreasing direction.

[0084] S102d, when the photovoltaic output voltage is less than or equal to the target bus voltage during the perturbation process, switch from the first control mode to the second control mode to adjust the photovoltaic output voltage until the maximum power point voltage is tracked.

[0085] S102e, control the input object to operate at the maximum power point voltage.

[0086] For example, if the currently obtained photovoltaic output voltage is about 700V, and at this time the photovoltaic output voltage is greater than the target bus voltage, then in the first control mode, control the photovoltaic output voltage to continuously perturb in a decreasing (from right to left) direction.

[0087] Similarly, the system can find the maximum power point through the perturbation observation method or the variable step size perturbation observation method.

[0088] During this process, the system will continuously monitor the relationship between the photovoltaic output voltage and the target bus voltage. When the photovoltaic output voltage drops to be less than or equal to the target bus voltage, the system will immediately trigger the control mode switching mechanism and switch from the first control mode to the second control mode. During the switching process, the system will make a smooth transition, substituting the parameters currently used in the first control mode into the second control mode to avoid sudden changes in voltage or current. In the second control mode, the boost circuit on the DC side starts to work, and at the same time, the maximum power point tracking is carried out by adjusting the equivalent resistance of the boost circuit until the maximum power point voltage is found. After finding the maximum power point voltage, the system controls the input object to operate stably at this voltage point, and then the boost circuit raises this voltage to the target bus voltage and outputs it to the AC side.

[0089] In some embodiments of the present application, in order to improve the reliability of switching, after triggering the switching condition, the system will sample continuously for multiple times to confirm that the photovoltaic output voltage is indeed less than or equal to the target bus voltage, so as to avoid mis-switching caused by instantaneous fluctuations. At the same time, the system will also record the working state before switching, so as to be able to find the maximum power point more quickly after switching.

[0090] Through the above improved control mode switching mechanism, the system can also respond more flexibly to changes in light intensity and load, ensuring efficient operation under various working conditions. At the same time, the smooth transition strategy and the multiple sampling confirmation mechanism improve the stability and reliability of the system, reducing the energy loss caused by mis-switching.

[0091] For Figure 3 the application scenario, in some embodiments of the present application, in S103, if the photovoltaic output voltage is less than or equal to the target bus voltage, adjusting the photovoltaic output voltage through the second control mode includes:

[0092] S103d, if the photovoltaic output voltage is less than or equal to the target bus voltage, then in the second control mode, control the photovoltaic output voltage to continuously perturb in the increasing direction.

[0093] S103e, if the maximum power point voltage is tracked during the perturbation of the photovoltaic output voltage and the maximum power point voltage is less than or equal to the target bus voltage, then control the input object to operate at the maximum power point voltage.

[0094] For example, if the currently obtained photovoltaic output voltage is less than 300V, which is less than the target bus voltage, then in the second control mode, control the photovoltaic output voltage to continuously perturb in the increasing direction (from left to right in the figure).

[0095] Similarly, the system can find the maximum power point through the perturbation observation method or the variable step size perturbation observation method. If the photovoltaic output voltage tracks the maximum power point voltage during the perturbation process, and the maximum power point voltage is less than or equal to the target bus voltage, then the input object is controlled to operate at the maximum power point voltage.

[0096] Through the step-by-step adjustment of the above second control mode, the system can quickly operate at the optimal efficiency point in this scenario.

[0097] To further reduce the adverse effects brought by mode switching, in some embodiments of the present application, a hysteresis logic can also be added during control. Exemplarily, as Figure 4 shown, the target bus voltage includes the first bus voltage (the voltage corresponding to point P7) and the second bus voltage (the voltage corresponding to point P6), the maximum power point voltage corresponds to the voltage corresponding to point P5, S102 the first bus voltage is greater than the second bus voltage, if the photovoltaic output voltage is greater than the target bus voltage, then the photovoltaic output voltage is adjusted through the first control mode, including:

[0098] S102f, if the photovoltaic output voltage is greater than the first bus voltage, then the photovoltaic output voltage is adjusted through the first control mode.

[0099] S102g, after adjusting the photovoltaic output voltage through the first control mode, if the photovoltaic output voltage is less than or equal to the first bus voltage and greater than or equal to the second bus voltage, then the first control mode is maintained to adjust the photovoltaic output voltage.

[0100] S102h, if the photovoltaic output voltage is less than the second bus voltage, then the first control mode is switched to the second control mode to adjust the photovoltaic output voltage.

[0101] Among them, the first bus voltage is the upper limit voltage of mode switching, and the second bus voltage is the lower limit voltage of mode switching. In practical applications, the first bus voltage can be set to 105% of the nominal bus voltage, and the second bus voltage can be set to 95% of the nominal bus voltage, so as to form a ±5% hysteresis band.

[0102] When the photovoltaic output voltage is greater than the first bus voltage, the system adopts the first control mode. After adjusting the photovoltaic output voltage in the first control mode, if the photovoltaic output voltage drops to less than or equal to the first bus voltage but is still greater than or equal to the second bus voltage, the system will maintain the first control mode and will not switch immediately. The setting of this hysteresis band effectively prevents the frequent switching of the control mode caused by the fluctuation of the photovoltaic output voltage near the critical value. Only when the photovoltaic output voltage further drops to less than the second bus voltage, the system will switch to the second control mode. During the switching process, the system will make a smooth transition to ensure the continuity of voltage and current and avoid system fluctuations.

[0103] If the photovoltaic output voltage is less than or equal to the target bus voltage, the photovoltaic output voltage is adjusted through the second control mode, including:

[0104] S103f, if the photovoltaic output voltage is less than the second bus voltage, the photovoltaic output voltage is adjusted through the second control mode;

[0105] S103g, after adjusting the photovoltaic output voltage through the second control mode, if the photovoltaic output voltage is less than or equal to the first bus voltage and greater than or equal to the second bus voltage, the second control mode for adjusting the photovoltaic output voltage is maintained;

[0106] S103h, if the photovoltaic output voltage is greater than the first bus voltage, the control mode is switched from the second control mode to the first control mode to adjust the photovoltaic output voltage.

[0107] When the photovoltaic output voltage is less than the second bus voltage, the system adopts the second control mode. After adjusting the photovoltaic output voltage in the second control mode, if the photovoltaic output voltage rises to be greater than or equal to the second bus voltage but still less than or equal to the first bus voltage, the system will maintain the second control mode and will not switch immediately. Only when the photovoltaic output voltage further rises to be greater than the first bus voltage, the system will switch to the first control mode. This two-way hysteresis design ensures that the system can make a smooth transition under various working conditions and avoids frequent switching of the control mode caused by changes in light intensity or load.

[0108] In some embodiments of the present application, the system can also dynamically adjust the values of the first bus voltage and the second bus voltage according to the change trend of the light intensity. For example, in the case of a rapid change in light intensity, the hysteresis band width can be appropriately increased to improve the stability of the system; in the case of relatively stable light intensity, the hysteresis band width can be reduced to improve the response speed of the system.

[0109] In the above embodiments, through the improved double-threshold mechanism, the system can operate more stably, effectively avoiding frequent switching of the control mode, and improving the reliability and service life of the system. At the same time, the strategy of dynamically adjusting the hysteresis band width enables the system to better adapt to different working environments and achieve the optimal energy conversion efficiency.

[0110] To facilitate better implementation of the mode control method of the present application, the present application also provides a mode control device based on the above mode control method. The meanings of the terms are the same as those in the above mode control method, and the specific implementation details can be referred to the description in the method embodiments.

[0111] Please refer to Figure 5 , Figure 5 which is a schematic structural diagram of the mode control device provided by the embodiments of the present application, and specifically may include:

[0112] A parameter acquisition module 501, configured to acquire the current photovoltaic output voltage and the target bus voltage of the input object;

[0113] A first control module 502, configured to, if the photovoltaic output voltage is greater than the target bus voltage, adjust the photovoltaic output voltage through a first control mode; wherein, in the first control mode, the DC side is in a direct-through state, and maximum power point tracking and inverter grid connection are performed through the AC side;

[0114] A second control module 503, configured to, if the photovoltaic output voltage is less than or equal to the target bus voltage, adjust the photovoltaic output voltage through a second control mode; wherein, in the second control mode, maximum power point tracking and boost are performed through the DC side, and inverter grid connection is performed through the AC side.

[0115] The above-mentioned mode control device provides a dual control mode, including a first control mode and a second control mode, and can automatically select the optimal control mode according to the relationship between the photovoltaic output voltage and the target bus voltage. The first control module 502 is used to adopt the first control mode when the photovoltaic output voltage is high. The DC boost circuit is in a direct-through mode and has no boost function, avoiding unnecessary switching losses and improving the power conversion efficiency of the photovoltaic inverter. Then, maximum power point tracking and inverter grid connection are performed through the AC side. The second control module 503 is used to adopt the second control mode when the photovoltaic output voltage is low. Maximum power point tracking and necessary boost operations are performed on the DC side, and inverter grid connection is performed on the AC side. Compared with the traditional single control mode, in this embodiment, regardless of whether the photovoltaic energy is sufficient, the system can always operate at the optimal efficiency point. And for the case where the photovoltaic energy is sufficient, the boost link can be optimized, thereby improving the power conversion efficiency of the photovoltaic inverter.

[0116] In some embodiments of the present application, the first control module 502 is specifically configured to: if the photovoltaic output voltage is greater than the target bus voltage, control the photovoltaic output voltage to continuously perturb in a decreasing direction in the first control mode; if the maximum power point voltage is tracked during the perturbation process of the photovoltaic output voltage and the maximum power point voltage is greater than the target bus voltage, control the input object to operate at the maximum power point voltage.

[0117] In some embodiments of the present application, the first control module 502 is specifically configured to: if the photovoltaic output voltage is greater than the target bus voltage, continuously perturb the photovoltaic output voltage in a decreasing direction in the first control mode; when the photovoltaic output voltage is less than or equal to the target bus voltage during the perturbation process, switch from the first control mode to the second control mode to adjust the photovoltaic output voltage until the maximum power point voltage is tracked; control the input object to operate at the maximum power point voltage.

[0118] In some embodiments of the present application, the second control module 503 is specifically configured to: if the photovoltaic output voltage is less than or equal to the target bus voltage, continuously perturb the photovoltaic output voltage in an increasing direction in the second control mode; if the maximum power point voltage is tracked during the perturbation process of the photovoltaic output voltage and the maximum power point voltage is less than or equal to the target bus voltage, control the input object to operate at the maximum power point voltage.

[0119] In some embodiments of the present application, the second control module 503 is specifically configured to: if the photovoltaic output voltage is less than or equal to the target bus voltage, continuously perturb the photovoltaic output voltage in an increasing direction in the second control mode; when the photovoltaic output voltage is greater than the target bus voltage during the perturbation process, switch from the second control mode to the first control mode to adjust the photovoltaic output voltage until the maximum power point voltage is tracked; control the input object to operate at the maximum power point voltage.

[0120] In some embodiments of the present application, the target bus voltage includes a first bus voltage and a second bus voltage, and the first bus voltage is greater than the second bus voltage. The first control module 502 is specifically configured to: if the photovoltaic output voltage is greater than the first bus voltage, adjust the photovoltaic output voltage through the first control mode; after adjusting the photovoltaic output voltage through the first control mode, if the photovoltaic output voltage is less than or equal to the first bus voltage and greater than or equal to the second bus voltage, maintain the first control mode to adjust the photovoltaic output voltage; if the photovoltaic output voltage is less than the second bus voltage, switch from the first control mode to the second control mode to adjust the photovoltaic output voltage.

[0121] In some embodiments of the present application, the target bus voltage includes a first bus voltage and a second bus voltage, and the first bus voltage is greater than the second bus voltage. The second control module 503 is specifically configured to: if the photovoltaic output voltage is less than the second bus voltage, adjust the photovoltaic output voltage through the second control mode; after adjusting the photovoltaic output voltage through the second control mode, if the photovoltaic output voltage is less than or equal to the first bus voltage and greater than or equal to the second bus voltage, maintain the second control mode to adjust the photovoltaic output voltage; if the photovoltaic output voltage is greater than the first bus voltage, switch from the second control mode to the first control mode to adjust the photovoltaic output voltage.

[0122] In addition, the present application also provides a terminal device, as Figure 6 shown, which shows a schematic structural diagram of the terminal device involved in the present application. Specifically:

[0123] The terminal device may include a processor 601 with one or more processing cores, a memory 602 with one or more computer-readable storage media, a power supply 603, an input unit 604, and other components. Those skilled in the art can understand that Figure 6 the structural diagram of the terminal device shown in does not constitute a limitation on the terminal device, and it may include more or fewer components than shown in the figure, or combine certain components, or have different component arrangements.

[0124] Among them:

[0125] The processor 601 is the control center of the terminal device, connecting various parts of the entire terminal device through various interfaces and lines, and executing various functions of the terminal device and processing data by running or executing software programs and / or modules stored in the memory 602, and calling data stored in the memory 602, so as to monitor the terminal device as a whole. Optionally, the processor 601 may include one or more processing cores; preferably, the processor 601 may integrate an application processor and a modulation and demodulation processor. Among them, the application processor mainly processes the operating system, user interface, application programs, etc., and the modulation and demodulation processor mainly processes wireless communication. It can be understood that the above modulation and demodulation processor may not be integrated into the processor 601.

[0126] The memory 602 can be used to store software programs and modules. The processor 601 executes various functional applications and data processing by running the software programs and modules stored in the memory 602. The memory 602 mainly includes a program storage area and a data storage area. Among them, the program storage area can store the operating system, application programs required for at least one function, etc.; the data storage area can store data created according to the use of the terminal device, etc. In addition, the memory 602 can include high-speed random access memory, and can also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other volatile solid-state storage devices. Accordingly, the memory 602 can also include a memory controller to provide the processor 601 with access to the memory 602.

[0127] The terminal device further includes a power supply 603 for powering each component. Preferably, the power supply 603 can be logically connected to the processor 601 through a power management system, so as to implement functions such as management of charging, discharging, and power consumption management through the power management system. The power supply 603 can also include any components such as one or more DC or AC power supplies, a recharge system, a power device debugging circuit, a power converter or inverter, and a power status indicator.

[0128] The terminal device may further include an input unit 604, which can be used to receive input digital or character information, and generate keyboard, mouse, joystick, optical or trackball signal inputs related to user settings and function controls.

[0129] Although not shown, the terminal device may further include a display unit, etc., which will not be elaborated here. Specifically, in this embodiment, the processor 601 in the terminal device will load the executable files corresponding to the processes of one or more application programs into the memory 602 according to the following instructions, and the processor 601 will run the application programs stored in the memory 602 to implement the steps in any of the mode control methods provided in the embodiments of the present application: obtaining the current photovoltaic output voltage and the target bus voltage of the input object; if the photovoltaic output voltage is greater than the target bus voltage, adjusting the photovoltaic output voltage through a first control mode; wherein, in the first control mode, the DC side is in a direct-through state, and maximum power point tracking and inversion grid connection are performed through the AC side; if the photovoltaic output voltage is less than or equal to the target bus voltage, adjusting the photovoltaic output voltage through a second control mode; wherein, in the second control mode, maximum power point tracking and boosting are performed through the DC side, and inversion grid connection is performed through the AC side.

[0130] This embodiment provides a dual control mode, including a first control mode and a second control mode, which can automatically select the optimal control mode according to the relationship between the photovoltaic output voltage and the target bus voltage. When the photovoltaic output voltage is high, the first control mode is adopted, and the DC boost circuit is in a through mode without boost function, avoiding unnecessary switching losses and improving the power conversion efficiency of the photovoltaic inverter. Then, the maximum power point tracking and inversion grid connection are carried out on the AC side. When the photovoltaic output voltage is low, the second control mode is adopted, and the maximum power point tracking and necessary boost operation are carried out on the DC side, and the inversion grid connection is carried out on the AC side. Compared with the traditional single control mode, the present invention can make the system always operate at the optimal efficiency point regardless of whether the photovoltaic energy is sufficient, and for the case of sufficient photovoltaic energy, the boost link can be optimized, thereby improving the power conversion efficiency of the photovoltaic inverter.

[0131] For the specific implementation of each of the above operations, reference can be made to the previous embodiments and will not be elaborated here.

[0132] Those of ordinary skill in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructions or by controlling related hardware through instructions. The instructions can be stored in a computer-readable storage medium and loaded and executed by a processor.

[0133] Therefore, this application provides a computer-readable storage medium on which a computer program is stored. The computer program can be loaded by a processor to execute the steps in any of the mode control methods provided by this application.

[0134] For the specific implementation of each of the above operations, reference can be made to the previous embodiments and will not be elaborated here.

[0135] Among them, the computer-readable storage medium may include: read-only memory (ROM, Read Only Memory), random access memory (RAM, Random Access Memory), magnetic disk or optical disk, etc.

[0136] Since the instructions stored in the computer-readable storage medium can execute the steps in any of the mode control methods provided by this application, the beneficial effects that can be achieved by any of the mode control methods provided by this application can be realized. For details, refer to the previous embodiments and will not be elaborated here.

[0137] The above has introduced in detail a mode control method, device, terminal device, and computer-readable storage medium provided by the present application. Specific examples are used in this article to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those skilled in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A mode control method, characterized in that, Applied to a photovoltaic inverter, the photovoltaic inverter includes a DC side and an AC side, and the method includes: Obtain the current photovoltaic output voltage and the target bus voltage of the input object; If the photovoltaic output voltage is greater than the target bus voltage, adjust the photovoltaic output voltage through a first control mode; wherein, in the first control mode, the DC side is in a through state, and maximum power point tracking and inverter grid connection are performed through the AC side; If the photovoltaic output voltage is less than or equal to the target bus voltage, adjust the photovoltaic output voltage through a second control mode; wherein, in the second control mode, maximum power point tracking and boosting are performed through the DC side, and inverter grid connection is performed through the AC side.

2. The pattern control method according to claim 1, wherein The step of "if the photovoltaic output voltage is greater than the target bus voltage, adjust the photovoltaic output voltage through a first control mode" includes: If the photovoltaic output voltage is greater than the target bus voltage, control the photovoltaic output voltage to continuously perturb in a decreasing direction in the first control mode; If the maximum power point voltage is tracked during the perturbation process of the photovoltaic output voltage, and the maximum power point voltage is greater than the target bus voltage, control the input object to operate at the maximum power point voltage.

3. The pattern control method according to claim 1, wherein The step of "if the photovoltaic output voltage is greater than the target bus voltage, adjust the photovoltaic output voltage through a first control mode" includes: If the photovoltaic output voltage is greater than the target bus voltage, control the photovoltaic output voltage to continuously perturb in a decreasing direction in the first control mode; When the photovoltaic output voltage is less than or equal to the target bus voltage during the perturbation process, switch from the first control mode to the second control mode to adjust the photovoltaic output voltage until the maximum power point voltage is tracked; Control the input object to operate at the maximum power point voltage.

4. The pattern control method according to claim 1, wherein The step of "if the photovoltaic output voltage is less than or equal to the target bus voltage, adjust the photovoltaic output voltage through a second control mode" includes: If the photovoltaic output voltage is less than or equal to the target bus voltage, control the photovoltaic output voltage to continuously perturb in an increasing direction in the second control mode; If the maximum power point voltage is tracked during the perturbation process of the photovoltaic output voltage, and the maximum power point voltage is less than or equal to the target bus voltage, control the input object to operate at the maximum power point voltage.

5. The pattern control method according to claim 1, wherein The step of "if the photovoltaic output voltage is less than or equal to the target bus voltage, adjust the photovoltaic output voltage through a second control mode" includes: If the photovoltaic output voltage is less than or equal to the target bus voltage, control the photovoltaic output voltage to continuously perturb in an increasing direction in the second control mode; When the photovoltaic output voltage is greater than the target bus voltage during the perturbation process, switch from the second control mode to the first control mode to adjust the photovoltaic output voltage until the maximum power point voltage is tracked; Control the input object to operate at the maximum power point voltage.

6. The pattern control method according to claim 1, wherein The target bus voltage includes a first bus voltage and a second bus voltage, the first bus voltage being greater than the second bus voltage. If the photovoltaic output voltage is greater than the target bus voltage, adjusting the photovoltaic output voltage through a first control mode includes: If the photovoltaic output voltage is greater than the first bus voltage, adjusting the photovoltaic output voltage through the first control mode; After adjusting the photovoltaic output voltage through the first control mode, if the photovoltaic output voltage is less than or equal to the first bus voltage and greater than or equal to the second bus voltage, maintaining the adjustment of the photovoltaic output voltage in the first control mode; If the photovoltaic output voltage is less than the second bus voltage, switching from the first control mode to the second control mode to adjust the photovoltaic output voltage.

7. The pattern control method according to claim 1, wherein The target bus voltage includes a first bus voltage and a second bus voltage, the first bus voltage being greater than the second bus voltage. If the photovoltaic output voltage is less than or equal to the target bus voltage, adjusting the photovoltaic output voltage through a second control mode includes: If the photovoltaic output voltage is less than the second bus voltage, adjusting the photovoltaic output voltage through the second control mode; After adjusting the photovoltaic output voltage through the second control mode, if the photovoltaic output voltage is less than or equal to the first bus voltage and greater than or equal to the second bus voltage, maintaining the adjustment of the photovoltaic output voltage in the second control mode; If the photovoltaic output voltage is greater than the first bus voltage, switching from the second control mode to the first control mode to adjust the photovoltaic output voltage.

8. A mode control device, characterized in that, Applied to a photovoltaic inverter, the photovoltaic inverter includes a DC side and an AC side, and the mode control device includes: A parameter acquisition module for acquiring the current photovoltaic output voltage and the target bus voltage of the input object; A first control module for, if the photovoltaic output voltage is greater than the target bus voltage, adjusting the photovoltaic output voltage through a first control mode; wherein, in the first control mode, the DC side is in a direct connection state, and maximum power point tracking and inverter grid connection are performed through the AC side; A second control module for, if the photovoltaic output voltage is less than or equal to the target bus voltage, adjusting the photovoltaic output voltage through a second control mode; wherein, in the second control mode, maximum power point tracking and boosting are performed through the DC side, and inverter grid connection is performed through the AC side.

9. A computer-readable storage medium, characterized in that, Stores a computer program, which when executed by a processor causes the processor to execute the steps of the method according to any one of claims 1 to 7.

10. A terminal device, characterized in that, Includes a memory and a processor, the memory stores a computer program, which when executed by the processor causes the processor to execute the steps of the method according to any one of claims 1 to 7.

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