A maximum power point tracking method, device, equipment and medium for photovoltaic system

Abstract

The present invention relates to the field of new energy technology, and in particular to a maximum power point tracking method, device, equipment and medium for a photovoltaic system. The maximum power point tracking method for a photovoltaic system provided by an embodiment of the present invention uses sawtooth wave fluctuations to perturb the input voltage to track the maximum power point during the tracking process, that is, the input voltage is perturbed with a preset step size so that it is perturbed between a first perturbation state, a second perturbation state and a third perturbation state. Therefore, perturbation in the form of sawtooth wave fluctuations can track the maximum power point more quickly, greatly improving the tracking efficiency and tracking speed, so that the energy transmitted by the photovoltaic system can be input to products such as batteries with maximum efficiency, thereby improving the performance of the battery, and also improving the economy and reliability of solar power generation and its adaptability to environmental changes.

Description

Technical Field

[0001] The present invention relates to the field of new energy technology, and in particular to a maximum power point tracking method, device, equipment and medium for a photovoltaic system. Background Art

[0002] In the field of new energy technologies, maximum power point tracking (MPPT) technology is key to improving the conversion of light energy into electricity in solar photovoltaic systems, significantly enhancing tracking efficiency and speed. Traditional MPPT algorithms, such as the perturbation-and-observe method and the incremental conductance method, often present various risks in complex and diverse practical environments, including poor stability, slow response, low tracking accuracy, and slow speed. Summary of the Invention

[0003] In view of this, the present invention provides a maximum power point tracking method, device, equipment and medium for a photovoltaic system to solve the problem of slow tracking speed of the MPPT algorithm in the prior art.

[0004] In a first aspect, the present invention provides a maximum power point tracking method for a photovoltaic system, the method comprising: obtaining the input voltage, output voltage and output current of the photovoltaic system in a current period, and determining the output power of the current period based on the output voltage and output current; judging whether the output power of the current period is greater than or equal to the marked maximum power; when the output power of the current period is less than the marked maximum power, performing a first preset number of disturbances in a sawtooth-shaped fluctuation between a first disturbance state, a second disturbance state and a third disturbance state according to a preset step size, and obtaining the input voltage, output voltage and output current of each disturbance, and obtaining the maximum output power and the minimum output power during the first disturbance; adjusting the preset step size based on the relationship between the maximum output power and the minimum output power or the relationship between the maximum output power and the marked maximum power; performing disturbances during a preset number of disturbances according to the adjusted step size and the relationship between the maximum output power and the marked maximum power, and obtaining the maximum output power in the disturbance as the new marked maximum power, and the maximum power point voltage is the input voltage after the disturbance.

[0005] The maximum power point tracking method for a photovoltaic system provided by an embodiment of the present invention uses sawtooth wave fluctuations to perturb the input voltage during the tracking process to track the maximum power point. That is, the input voltage is perturbed with a preset step size so that it fluctuates between a first perturbation state, a second perturbation state, and a third perturbation state. Thus, perturbing the input voltage in the form of sawtooth wave fluctuations allows for faster tracking of the maximum power point, greatly improving tracking efficiency and speed. This allows the energy transmitted by the photovoltaic system to be input to products such as batteries with maximum efficiency, improving battery performance, and also enhancing the economy, reliability, and adaptability of solar power generation to changing environments.

[0006] In an optional embodiment, when the output power of the current time period is less than the marked maximum power, a first preset number of disturbances are performed between the first disturbance state, the second disturbance state and the third disturbance state in a sawtooth-shaped fluctuation according to a preset step size, including: when the output power of the current time period is less than the marked maximum power, entering the first disturbance state, controlling the input voltage or the voltage reference value to increase by a preset step size, and the voltage reference value is a given voltage value in the fixed voltage maximum power point tracking; judging whether the increased input voltage or voltage reference value is greater than the disturbance upper limit of this disturbance process; when it is not greater than the disturbance upper limit, continuing to control the input voltage or voltage reference value to increase by a preset step size, and the number of disturbances increases by 1 each time it increases; when it is greater than the disturbance upper limit, entering the second disturbance state. The method comprises the following steps: entering a first disturbance state, controlling the input voltage or voltage reference value to decrease by a preset step size; judging whether the decreased input voltage or voltage reference value is less than the disturbance lower limit of this disturbance process; when it is not less than the disturbance lower limit, continuing to control the input voltage or voltage reference value to decrease by a preset step size, and increasing the disturbance count by 1 each time it decreases; when it is less than the disturbance lower limit, entering a third disturbance state, controlling the input voltage or voltage reference value to increase by a preset step size; judging whether the increased input voltage or voltage reference value is greater than the output voltage; when it is not greater than the output voltage, continuing to control the input voltage or voltage reference value to increase by a preset step size, and increasing the disturbance count by 1 each time it increases; and entering a first disturbance state, repeating the above process until the disturbance count reaches the first preset count.

[0007] In an optional embodiment, the upper limit of the disturbance process is the sum of the output voltage of the previous disturbance process and ten times the preset step size, and the lower limit of the disturbance process is the difference between the output voltage of the previous disturbance process and ten times the preset step size.

[0008] In this embodiment, the sum of the output voltage of the previous disturbance process and ten times the preset step size is used as the disturbance upper limit of this disturbance process, and the difference between the output voltage of the previous disturbance process and ten times the preset step size is used as the disturbance lower limit of this disturbance, and then a disturbance in the form of a sawtooth wave is formed between the disturbance upper limit and the disturbance lower limit, wherein the disturbance is continued before reaching the disturbance upper limit or the disturbance lower limit. Thus, the maximum power point can be tracked faster through the disturbance method in the form of the sawtooth wave, which improves the tracking rate compared to the disturbance observation method.

[0009] In an optional embodiment, the preset step size is adjusted based on the relationship between the maximum output power and the minimum output power or the relationship between the maximum output power and the marked maximum power, including: calculating a first difference between the maximum output power and the minimum output power or a second difference between the maximum output power and the marked maximum power; when the first difference is greater than a third preset value or the second difference is greater than a fifth preset value, the preset step size remains unchanged; when the first difference is less than or equal to the third preset value and greater than a fourth preset value or the second difference is less than the fifth preset value or greater than the sixth preset value, the preset step size is adjusted to the second preset step size; when the first difference is less than or equal to the fourth preset value or the second difference is less than or equal to the sixth preset value, the preset step size is adjusted to the third preset step size, the third preset value is greater than the fourth preset value, the fifth preset value is greater than the sixth preset value, the preset step size is greater than the second preset step size, and the second preset step size is greater than the third preset step size.

[0010] In this embodiment, the step size is adjusted according to the size of the difference between the maximum output power and the minimum output power or the maximum output power and the marked maximum power. When the difference is large, the step size is adjusted to a larger one, and when the difference is small, the step size is adjusted to a smaller one, thereby improving the tracking accuracy.

[0011] In an optional embodiment, disturbance is performed during a preset number of disturbance periods according to the adjusted step size and the relationship between the maximum output power and the marked maximum power, and the maximum output power in the disturbance is obtained as the new marked maximum power, and the maximum power point voltage is the input voltage after the disturbance, including: when the maximum output power is greater than or equal to the marked maximum power, the maximum output power is used as the marked maximum power, and the output power determination, judgment and disturbance process during the disturbance are repeated until the preset number of disturbance periods are reached, and the maximum output power in the disturbance is obtained as the new marked maximum power, and the maximum power point voltage is the input voltage after the disturbance; when the maximum output power is less than the marked maximum power, the marked maximum power is kept unchanged, and the output power determination, judgment and disturbance process during the disturbance are repeated until the preset number of disturbance periods are reached, and the maximum output power in the disturbance is obtained as the new marked maximum power, and the maximum power point voltage is the input voltage after the disturbance.

[0012] In this embodiment, based on the relationship between the maximum output power during the disturbance period and the marked maximum power, a larger power and an adjusted step size are selected as the benchmark for the next disturbance period, and disturbances are performed during multiple disturbance periods, so that the maximum power can be tracked more quickly and accurately, thereby improving the accuracy and stability of the disturbance.

[0013] In an optional embodiment, the method further includes: when the output power of the current period is greater than or equal to the marked maximum power, using the output power of the current period as the marked maximum power point, and the maximum power point voltage is the output voltage of the current period.

[0014] In an optional embodiment, before obtaining the input voltage, output voltage, and output current of the photovoltaic system in the current period, and determining the output power of the current period based on the output voltage and output current, the method further includes: determining whether the photovoltaic system is in an aging mode; and when in the aging mode, fixing the maximum power point voltage to a preset maximum power point voltage.

[0015] In this embodiment, when it is determined that the system is in the aging mode, the maximum power point voltage is fixed, thereby reducing the requirements for power supply testing equipment and reducing the power supply equipment cost caused by aging.

[0016] In a second aspect, the present invention provides a maximum power point tracking device for a photovoltaic system, the device comprising: a parameter acquisition module for acquiring the input voltage, output voltage and output current of the photovoltaic system in the current period, and determining the output power of the current period based on the output voltage and output current; a judgment module for judging whether the output power of the current period is greater than or equal to the marked maximum power; a disturbance module for performing a first preset number of disturbances in a sawtooth-shaped fluctuation between a first disturbance state, a second disturbance state and a third disturbance state according to a preset step size when the output power of the current period is less than the marked maximum power, and obtaining the input voltage, output voltage and output current of each disturbance to obtain the maximum output power and the minimum output power during the first disturbance; a step size adjustment module for adjusting the preset step size based on the relationship between the maximum output power and the minimum output power or the relationship between the maximum output power and the marked maximum power; a maximum power point determination module for performing a preset number of disturbances during the disturbance according to the adjusted step size and the relationship between the maximum output power and the marked maximum power, and obtaining the maximum output power in the disturbance as the marked maximum power, and the maximum power point voltage is the input voltage after the disturbance.

[0017] In a third aspect, the present invention provides a computer device comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to thereby execute the maximum power point tracking method for a photovoltaic system according to the first aspect or any corresponding embodiment thereof.

[0018] In a fourth aspect, the present invention provides a computer-readable storage medium having computer instructions stored thereon, the computer instructions being used to enable a computer to execute the maximum power point tracking method for a photovoltaic system according to the first aspect or any corresponding embodiment thereof.

[0019] In a fifth aspect, the present invention provides a computer program product comprising computer instructions for causing a computer to execute the maximum power point tracking method for a photovoltaic system according to the first aspect or any corresponding embodiment thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 is a schematic flow chart of a maximum power point tracking method for a photovoltaic system according to an embodiment of the present invention;

[0022] Figure 2 is a schematic diagram of a UW curve according to an embodiment of the present invention;

[0023] Figure 3 is a schematic diagram of a disturbance process according to an embodiment of the present invention;

[0024] Figure 4 is a flow chart of a maximum power point tracking method for a photovoltaic system according to an embodiment of the present invention;

[0025] Figure 5 is a structural block diagram of a maximum power point tracking device for a photovoltaic system according to an embodiment of the present invention;

[0026] Figure 6 Schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0028] According to an embodiment of the present invention, an embodiment of a maximum power point tracking method for a photovoltaic system is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a 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 here.

[0029] In this embodiment, a maximum power point tracking method for a photovoltaic system is provided, which can be used in electronic devices such as computers, mobile phones, tablet computers, etc. Figure 1 FIG. 1 is a flow chart of a maximum power point tracking method for a photovoltaic system according to an embodiment of the present invention. Figure 1 As shown, the process includes the following steps:

[0030] Step S101: Obtain the input voltage, output voltage, and output current of the photovoltaic system during the current period, and determine the output power during the current period based on the output voltage and output current. When performing maximum power point tracking, the initial operating state of the photovoltaic system must first be obtained. This initial operating state includes the initial input voltage, the initial maximum power point voltage / initial maximum power point, and the initial open-circuit voltage. The initial open-circuit voltage is equal to the initial input voltage. The initial input voltage and initial maximum power point voltage can be pre-set based on actual conditions. For example, the initial input voltage is 20V, the initial maximum power point voltage is 0.8*2V, and the initial maximum power point is 0.

[0031] During the tracking process, the battery management system obtains the current state, namely the input voltage, output voltage, and output current of the current period. To make the acquired data more accurate, multiple input voltages, output voltages, and output currents can be acquired over a continuous period of time, such as 1 second. Furthermore, to achieve maximum power point tracking, the output voltage and output current are multiplied to obtain the output power. This yields multiple input voltages and multiple output powers. These multiple output powers are then sorted and filtered to obtain the maximum value of the multiple output powers, which is then used as the output power for the current period.

[0032] Step S102: Determine whether the output power of the current period is greater than or equal to the marked maximum power. Specifically, in order to track the maximum power point, the output power of the current period is compared with the marked maximum power, where the marked maximum power is the maximum power value determined by the last maximum power point tracking.

[0033] Step S103: When the output power of the current period is less than the marked maximum power, a first preset number of disturbances are performed between the first disturbance state, the second disturbance state and the third disturbance state in a sawtooth-shaped fluctuation according to a preset step size, and the input voltage, output voltage and output current of each disturbance are obtained to obtain the maximum output power and the minimum output power during the first disturbance.

[0034] Specifically, when the output power of the current time period is less than the marked maximum power, the maximum power point is tracked in a perturbation manner. During the perturbation, the input voltage or voltage reference value is disturbed to cause it to fluctuate in the form of a sawtooth wave between a first perturbation state, a second perturbation state, and a third perturbation state. In the sawtooth wave, the first perturbation state is a state before reaching the peak of the sawtooth wave, the second perturbation state is a state between the peak and the trough of the sawtooth wave, and the third perturbation state is a state after the trough of the sawtooth wave. At the same time, the limits on the peaks and troughs can be determined by the last perturbation process. The preset step size can be determined before tracking, for example, during the initialization process. Among them, the voltage reference value is a given voltage value in the fixed voltage maximum power point tracking.

[0035] In addition, when performing a perturbation, each perturbation step of a preset length completes a perturbation, and the input voltage, output voltage, and output current are obtained once, and the output power is calculated based on the output voltage and output current. When the number of perturbations reaches a first preset number, the perturbation period is completed. The output powers calculated for each perturbation within the perturbation period are sorted to obtain the maximum and minimum values.

[0036] Step S104, adjusting the preset step size based on the relationship between the maximum output power and the minimum output power or the relationship between the maximum output power and the marked maximum power; specifically, the relationship between the relationship and the step size can be set in advance, and then after obtaining the relationship between the maximum output power and the minimum output power or the relationship between the maximum output power and the marked maximum power, the adjusted step size is determined according to the relationship between the two.

[0037] Step S105 , performing disturbances during a preset number of disturbances according to the adjusted step size and the relationship between the maximum output power and the marked maximum power, and obtaining the maximum output power during the disturbance as the new marked maximum power, and the maximum power point voltage is the input voltage after the disturbance.

[0038] Specifically, after adjusting the step size, the relationship between the maximum output power and the marked maximum power during the disturbance period is further determined and a new marked maximum power is determined. After determining the new marked maximum power, steps S101 to S104 can be repeated to perform disturbances for a preset number of disturbance periods. For example, if the preset number is four, steps S101 to S104 are performed four times. The maximum output power during the disturbance is then obtained as the marked maximum power point, and the maximum power point voltage is the input voltage after the disturbance.

[0039] The maximum power point tracking method for a photovoltaic system provided by an embodiment of the present invention uses sawtooth wave fluctuations to perturb the input voltage during the tracking process to track the maximum power point. That is, the input voltage is perturbed with a preset step size so that it fluctuates between a first perturbation state, a second perturbation state, and a third perturbation state. Thus, perturbing the input voltage in the form of sawtooth wave fluctuations allows for faster tracking of the maximum power point, greatly improving tracking efficiency and speed. This allows the energy transmitted by the photovoltaic system to be input to products such as batteries with maximum efficiency, improving battery performance, and also enhancing the economy, reliability, and adaptability of solar power generation to changing environments.

[0040] In this embodiment, a maximum power point tracking method for a photovoltaic system is provided, and the process includes the following steps:

[0041] Step S201: Obtain the input voltage, output voltage, and output current of the photovoltaic system in the current period, and determine the output power of the current period based on the output voltage and output current. Figure 1 Step S101 of the illustrated embodiment will not be described in detail here.

[0042] Step S202: Determine whether the output power of the current period is greater than or equal to the marked maximum power. Figure 1 Step S102 of the illustrated embodiment will not be described in detail here.

[0043] Step S203: When the output power of the current period is less than the marked maximum power, a first preset number of disturbances are performed in a sawtooth-shaped fluctuation between the first disturbance state, the second disturbance state, and the third disturbance state according to a preset step size, and the input voltage, output voltage, and output current of each disturbance are obtained to obtain the maximum output power and the minimum output power during the first disturbance period;

[0044] Specifically, the above step S203 includes:

[0045] Step S2031: When the output power in the current period is less than the marked maximum power, the system enters the first disturbance state and controls the input voltage or the voltage reference value to increase by a preset step size. The voltage reference value is a given voltage value in the fixed voltage maximum power point tracking.

[0046] Step S2032 , determining whether the increased input voltage or voltage reference value is greater than the disturbance upper limit of the current disturbance process.

[0047] Step S2033: When the value is not greater than the upper disturbance limit, the input voltage or the voltage reference value is continuously controlled to increase by a preset step size, and the number of disturbances is increased by 1 each time the step size is increased.

[0048] Step S2034: When the voltage is greater than the upper disturbance limit, the system enters the second disturbance state and controls the input voltage or the voltage reference value to decrease in a preset step size.

[0049] Step S2035 , determining whether the decreased input voltage or voltage reference value is less than the disturbance lower limit of this disturbance process.

[0050] Step S2036: When the value is not less than the lower disturbance limit, the input voltage or the voltage reference value is continuously controlled to decrease by a preset step size, and the number of disturbances is increased by 1 each time the step size is decreased.

[0051] Step S2037: When the voltage is less than the lower disturbance limit, the system enters the third disturbance state, and controls the input voltage or the voltage reference value to increase by a preset step size.

[0052] Step S2038, determining whether the increased input voltage or voltage reference value is greater than the output voltage of this disturbance process.

[0053] Step S2039: When the value is not greater than the output voltage, continue to control the input voltage or the voltage reference value to increase by a preset step size, and the number of disturbances increases by 1 each time the step size is increased.

[0054] Step S20310: When the voltage is greater than the output voltage, the system enters the first disturbance state and repeats the above process until the number of disturbances reaches a first preset number.

[0055] Specifically, taking the input voltage disturbance as an example, the above disturbance process is explained as follows: when the output power of the current period is less than the marked maximum power, the first disturbance state is entered, and the input voltage is controlled to increase by a preset step size. For example, if the input voltage is 20V and increases by a preset step size of 0.4V, the input voltage after one increment is 20.4V. Then, it is determined whether the increased input voltage is greater than the disturbance upper limit of this disturbance process. If the increased input voltage is not greater than the disturbance upper limit, the increase is continued. At the same time, each increase is compared with the disturbance upper limit until the increased input voltage is greater than the disturbance upper limit, and then the second disturbance state is entered.

[0056] In the second disturbance state, the control input voltage is decreased in a preset step size, and each time it is decreased, the decreased input voltage is compared with the disturbance lower limit of this disturbance process until the decreased input voltage is less than the disturbance lower limit of this disturbance process. When it is determined that the decreased input voltage is less than the disturbance lower limit, the third disturbance state is entered. In the third disturbance state, the control input voltage is increased in a preset step size, and each time it is increased, the increased input voltage is compared with the output voltage until the increased input voltage is greater than the output voltage, and the next first disturbance state is entered. Wherein, each time a disturbance is performed, the input voltage, output voltage and output current are obtained once, and the output voltage of the comparison is the output voltage obtained after the corresponding increased input voltage.

[0057] In addition, the upper limit of the disturbance process is the sum of the output voltage of the previous disturbance process and ten times the preset step length. The lower limit of the disturbance process is the difference between the output voltage of the previous disturbance process and ten times the preset step length. Figure 2 As shown in the figure, it is a schematic diagram of the UW curve of the output voltage U (unit is V) and the output power P (unit is W). The sawtooth wave in the figure is the disturbance added at time Tn. Figure 3 Figure 1 is a schematic diagram of a disturbance process. A disturbance process starts from entering the first disturbance state, passes through the second disturbance state and the third disturbance state, and ends before entering the next first disturbance state after the third disturbance state. Therefore, the output voltage of the previous disturbance process is the output voltage after the third disturbance state of the previous disturbance process ends.

[0058] Step S204: Adjust the preset step size based on the relationship between the maximum output power and the minimum output power or the relationship between the maximum output power and the marked maximum power. Figure 1 Step S104 of the illustrated embodiment will not be described in detail here.

[0059] Step S205: Perform disturbances for a preset number of disturbances according to the adjusted step size and the relationship between the maximum output power and the marked maximum power, and obtain the maximum output power during the disturbance as the new marked maximum power. The maximum power point voltage is the input voltage after the disturbance. Figure 1 Step S105 of the illustrated embodiment will not be described in detail here.

[0060] In this embodiment, a maximum power point tracking method for a photovoltaic system is provided, the method comprising the following steps:

[0061] Step S301 determines whether the photovoltaic system is in burn-in mode. If so, the maximum power point voltage is fixed to a preset maximum power point voltage. Specifically, after production, the photovoltaic system undergoes a performance test or stress test. The test results determine whether it is in burn-in mode. If so, the maximum power point voltage is fixed to a preset maximum power point voltage, i.e., a certain value. If not, the following steps S302 through S307 are executed.

[0062] Step S302: Obtain the input voltage, output voltage, and output current of the photovoltaic system during the current period, and determine the output power of the current period based on the output voltage and output current; see Figure 1 Step S101 of the illustrated embodiment will not be described in detail here.

[0063] Step S303: determine whether the output power of the current period is greater than or equal to the marked maximum power; see Figure 1 Step S102 of the illustrated embodiment will not be described in detail here.

[0064] In step S304, when the output power of the current period is greater than or equal to the marked maximum power, the output power of the current period is used as the marked maximum power point, and the maximum power point voltage is used as the output voltage of the current period. The marked maximum power may be the maximum power point of the photovoltaic system under the current environment, which may vary with factors such as light intensity and temperature. Therefore, when the current output power is greater than or equal to the marked maximum power, the current output power may be used as the new marked maximum power, which can be used as the benchmark for the next tracking operation.

[0065] Step S305: When the output power of the current period is less than the marked maximum power, a first preset number of disturbances are performed between the first disturbance state, the second disturbance state, and the third disturbance state in a sawtooth-shaped fluctuation according to a preset step size, and the input voltage, output voltage, and output current of each disturbance are obtained to obtain the maximum output power and the minimum output power during the first disturbance period; see details in Figure 1 Step S103 of the illustrated embodiment will not be described in detail here.

[0066] Step S306: adjusting the preset step size based on the relationship between the maximum output power and the minimum output power or the relationship between the maximum output power and the marked maximum power.

[0067] Specifically, the above step S306 includes:

[0068] Step S3061, calculating a first difference between the maximum output power and the minimum output power or a second difference between the maximum output power and the marked maximum power;

[0069] Step S3062: When the first difference is greater than a third preset value or the second difference is greater than a fifth preset value, the preset step size remains unchanged;

[0070] Step S3063: When the first difference is less than or equal to the third preset value and greater than the fourth preset value, or the second difference is less than the fifth preset value and greater than the sixth preset value, the preset step size is adjusted to the second preset step size;

[0071] Step S3064: When the first difference is less than or equal to the fourth preset value or the second difference is less than or equal to the sixth preset value, the preset step size is adjusted to the third preset step size, the third preset value is greater than the fourth preset value, the fifth preset value is greater than the sixth preset value, the preset step size is greater than the second preset step size, and the second preset step size is greater than the third preset step size. Specifically, the process is described using the calculation of the first difference and the adjustment of the step size based on the first difference as an example: after determining the maximum output power and the minimum output power within a disturbance period, the first difference between the two can be obtained, and then it is determined in which range the first difference falls, so as to adjust the step size based on the range. Among them, when the first difference is greater than the third preset value, such as greater than 30, it means that the power change during the disturbance process is large, and the original larger preset step size, such as 0.4, can be kept unchanged; when the first difference is between the fourth preset value and the third preset value, such as between 20 and 30, it means that the power has decreased during the disturbance process, and the preset step size can be relatively reduced, such as adjusting the preset step size from 0.4 to 0.3; when the first difference is less than the fourth preset value, such as less than 20, it means that the power change during the disturbance process is also relatively small, and the preset step size can be adjusted to a smaller value, such as 0.3. The process of calculating the second difference and adjusting the step size according to the second difference is the same as the above process and will not be repeated here.

[0072] Step S307: Perform disturbances during the preset number of disturbances according to the adjusted step size and the relationship between the maximum output power and the marked maximum power, and obtain the maximum output power during the disturbance as the new marked maximum power. The maximum power point voltage is the input voltage after the disturbance.

[0073] Specifically, the above step S307 includes:

[0074] Step S3071: When the maximum output power is greater than or equal to the marked maximum power, the maximum output power is used as the marked maximum power, and the output power determination, judgment, and disturbance process during the disturbance are repeated until the preset number of disturbances is reached. The maximum output power during the disturbance is obtained as the new marked maximum power, and the maximum power point voltage is the input voltage after the disturbance.

[0075] Step S3072: When the maximum output power is less than the marked maximum power, the marked maximum power is kept unchanged, and the output power determination, judgment, and disturbance process during the disturbance are repeated until the preset number of disturbances is reached. The maximum output power during the disturbance is obtained as the new marked maximum power, and the maximum power point voltage is the input voltage after the disturbance.

[0076] Specifically, if the maximum output power determined during the first disturbance is greater than or equal to the marked maximum power, the maximum output power is used as the new marked maximum power; if the maximum output power determined during the first disturbance is less than the marked maximum power, the marked maximum power remains unchanged. Then, with the adjusted step size as the preset step size, the above steps S302 to S306 are executed, and a new maximum output power is obtained. The new maximum output power is compared with the new marked maximum power to determine whether to modify the marked maximum power. Then, the above steps S302 to S306 are executed again with the adjusted step size as the preset step size, and the above process is repeated until the maximum output power during the fifth disturbance is obtained. During these five disturbances, if the condition of step S304 is met, the tracking ends; if the condition of step S304 is not met, the five maximum output power values ​​obtained during the five disturbances are sorted from large to small, and the output power maximum value ranked closest is used as the maximum power point. It should be noted that the number of times the disturbance is executed can be determined according to actual needs, and can be five times or ten times. Or other times, etc.

[0077] As a specific application example of the embodiment of the present invention, Figure 4 As shown, the maximum power point tracking of the photovoltaic system can be achieved according to the following process:

[0078] 1. Obtain the input voltage Vin, output current, and output voltage of the initial working state, and set the open circuit voltage Voc = Vin, the maximum power point voltage Vpp = Voc * 0.8, and the maximum power point Pmax = 0.

[0079] 2. Obtain the current input voltage Vin, output current, and output voltage. If the output power Px calculated based on the output current and output voltage is greater than or equal to the maximum power point Pmax, use the output power as the maximum power point, i.e., Pmax = Px, and use the open-circuit voltage Voc as the maximum power point voltage Vpp, i.e., Vpp = Voc. If the output power is less than the maximum power point, execute the following process.

[0080] 3. Perturb the input voltage Vin or the voltage reference value Vref in the form of a sawtooth wave, and obtain multiple output powers Pn during the disturbance and the input voltage Vn_in after the disturbance.

[0081] 4. Filter and sort multiple output powers Pn during the disturbance period, compare the processed maximum output power Pn_max with the maximum power point Pmax, and determine the maximum power point Pmax (new maximum power point) and maximum power point voltage Vpp at the current moment based on the comparison result. At the same time, calculate the difference △P between the maximum output power and the minimum output power, as well as the difference between the maximum output power and the marked maximum power based on the sorting result, and adjust the preset step size Vset according to the size of the difference.

[0082] 5. Repeat the above steps 1, 2, 3, and 4 based on the determined new maximum power and the adjusted step size, i.e., perform a new disturbance during the disturbance period, and then perform the above steps 1, 2, 3, and 4 again based on the result after the disturbance, and then repeat this process until the disturbance period has been performed M times. If Pmax and Vpp are not obtained during the disturbance for M consecutive times, i.e., the output power does not meet the conditions in step 2 for M consecutive times, then filter and sort the maximum output power Pn_max and input voltage Vn_in obtained in the M times to determine the maximum values ​​Pnm_max and Vnm_in, and then use Vnm_in as the maximum power point voltage, i.e., Vpp = Vnm_in, and use Pnm_max as the maximum power point, i.e., Pmax = Pnm_max.

[0083] This embodiment also provides a maximum power point tracking device for a photovoltaic system, which is used to implement the above-mentioned embodiments and preferred implementations. Details already described will not be repeated here. As used below, the term "module" may refer to a combination of software and / or hardware that implements a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation using hardware, or a combination of software and hardware, is also possible and contemplated.

[0084] This embodiment provides a maximum power point tracking device for a photovoltaic system, such as Figure 5 Shown, including:

[0085] A parameter acquisition module 51 is used to obtain the input voltage, output voltage, and output current of the photovoltaic system in the current period, and determine the output power in the current period based on the output voltage and output current;

[0086] A judging module 52 is configured to judge whether the output power in the current period is greater than or equal to the marked maximum power;

[0087] a disturbance module 53 configured to, when the output power of the current period is less than the marked maximum power, perform disturbances for a first preset number of times in a sawtooth-shaped fluctuation between a first disturbance state, a second disturbance state, and a third disturbance state according to a preset step size, obtain the input voltage, output voltage, and output current of each disturbance, and obtain the maximum output power and the minimum output power during the first disturbance period;

[0088] a step size adjustment module 54 for adjusting a preset step size based on a relationship between a maximum output power and a minimum output power or a relationship between a maximum output power and a marked maximum power;

[0089] The maximum power point determination module 55 performs disturbances during a preset number of disturbances according to the adjusted step size and the relationship between the maximum output power and the marked maximum power, and obtains the maximum output power during the disturbance as the new marked maximum power. The maximum power point voltage is the input voltage after the disturbance.

[0090] In an optional embodiment, the disturbance module is specifically used to: when the output power of the current period is less than the marked maximum power, enter the first disturbance state, control the input voltage or voltage reference value to increase by a preset step size, and the voltage reference value is a given voltage value in the fixed voltage maximum power point tracking; judge whether the increased input voltage or voltage reference value is greater than the disturbance upper limit of this disturbance process; when it is not greater than the disturbance upper limit, continue to control the input voltage or voltage reference value to increase by a preset step size, and increase the number of disturbances by 1 each time it increases; when it is greater than the disturbance upper limit, enter the second disturbance state, control the input voltage or voltage reference value to decrease by a preset step size; judge whether the decreased input voltage or voltage reference value is greater than the disturbance upper limit Whether the input voltage or voltage reference value is less than the disturbance lower limit of this disturbance process; when it is not less than the disturbance lower limit, continue to control the input voltage or voltage reference value to decrease by a preset step size, and the number of disturbances increases by 1 each time it decreases; when it is less than the disturbance lower limit, enter the third disturbance state, control the input voltage or voltage reference value to increase by a preset step size; determine whether the increased input voltage or voltage reference value is greater than the output voltage; when it is not greater than the output voltage, continue to control the input voltage or voltage reference value to increase by a preset step size, and the number of disturbances increases by 1 each time it increases; when it is greater than the output voltage, enter the first disturbance state, and repeat the above process until the number of disturbances reaches the first preset number.

[0091] In an optional embodiment, the upper limit of the disturbance process of this disturbance is the sum of the output voltage of the previous disturbance process and ten times the preset step size, and the lower limit of the disturbance process of this disturbance is the difference between the output voltage of the previous disturbance process and ten times the preset step size.

[0092] In an optional embodiment, the step adjustment module is specifically used to calculate a first difference between the maximum output power and the minimum output power or a second difference between the maximum output power and the marked maximum power; when the first difference is greater than a third preset value or the second difference is greater than a fifth preset value, the preset step remains unchanged; when the first difference is less than or equal to the third preset value and greater than a fourth preset value or the second difference is less than the fifth preset value or greater than the sixth preset value, the preset step is adjusted to the second preset step; when the first difference is less than or equal to the fourth preset value or the second difference is less than or equal to the sixth preset value, the preset step is adjusted to the third preset step, the third preset value is greater than the fourth preset value, the fifth preset value is greater than the sixth preset value, the preset step is greater than the second preset step, and the second preset step is greater than the third preset step.

[0093] In an optional embodiment, the maximum power point determination module is specifically used to perform disturbances during a preset number of disturbances according to the adjusted step size and the relationship between the maximum output power and the marked maximum power, and obtain the maximum output power in the disturbance as the new marked maximum power, and the maximum power point voltage is the input voltage after the disturbance, including: when the maximum output power is greater than or equal to the marked maximum power, using the maximum output power as the marked maximum power, repeating the output power determination, judgment and disturbance process during the disturbance until the preset number of disturbances is reached, obtaining the maximum output power in the disturbance as the new marked maximum power, and the maximum power point voltage is the input voltage after the disturbance; when the maximum output power is less than the marked maximum power, keeping the marked maximum power unchanged, repeating the output power determination, judgment and disturbance process during the disturbance until the preset number of disturbances is reached, obtaining the maximum output power in the disturbance as the new marked maximum power, and the maximum power point voltage is the input voltage after the disturbance.

[0094] In an optional embodiment, the device further includes: a judgment unit, configured to use the output power of the current period as the marked maximum power point when the output power of the current period is greater than or equal to the marked maximum power, and the maximum power point voltage is the output voltage of the current period.

[0095] In an optional embodiment, the device further includes: an aging adjustment module, configured to determine whether the photovoltaic system is in an aging mode; and when in the aging mode, fix the maximum power point voltage to a preset maximum power point voltage.

[0096] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0097] The embodiment of the present invention also provides a computer device having the above Figure 5 The maximum power point tracking device of the photovoltaic system is shown.

[0098] See also Figure 6 , Figure 6 is a structural diagram of a computer device provided by an optional embodiment of the present invention, such as Figure 6 As shown, the computer device includes: one or more processors 10, memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components utilize different buses to communicate with each other and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the computer device, including instructions stored in the memory or on the memory to display the graphical information of the GUI on an external input / output device (such as, a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Equally, multiple computer devices can be connected, and each device provides part of the necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Figure 6 A processor 10 is taken as an example.

[0099] The processor 10 may be a central processing unit, a network processor, or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit, a programmable logic device, or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic, or any combination thereof.

[0100] The memory 20 stores instructions that can be executed by at least one processor 10, so as to enable at least one processor 10 to execute the method shown in the above embodiment.

[0101] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created based on the use of a computer device for displaying a small program landing page, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely located relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof.

[0102] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0103] The computer device further includes a communication interface 30 for the computer device to communicate with other devices or a communication network.

[0104] The embodiment of the present invention also provides a computer-readable storage medium. The above-mentioned method according to the embodiment of the present invention can be implemented in hardware, firmware, or implemented as a computer code that can be recorded in a storage medium, or implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and downloaded through a network and will be stored in a local storage medium, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state drive, etc.; further, the storage medium can also include a combination of the above-mentioned types of memory. It can be understood that a computer, a processor, a microprocessor controller or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor or hardware, the method shown in the above embodiment is implemented.

[0105] A portion of the present invention may be applied as a computer program product, such as a computer program instruction, which, when executed by a computer, can call or provide the method and / or technical solution according to the present invention through the operation of the computer. Those skilled in the art should understand that the form in which the computer program instruction exists in a computer-readable medium includes, but is not limited to, a source file, an executable file, an installation package file, etc. Accordingly, the way in which the computer program instruction is executed by the computer includes, but is not limited to: the computer directly executes the instruction, or the computer compiles the instruction and then executes the corresponding compiled program, or the computer reads and executes the instruction, or the computer reads and installs the instruction and then executes the corresponding installed program. Here, the computer-readable medium may be any available computer-readable storage medium or communication medium that can be accessed by the computer.

[0106] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A maximum power point tracking method for a photovoltaic system, characterized in that: The method comprises: Obtaining the input voltage, output voltage, and output current of the photovoltaic system during the current period, and determining the output power during the current period based on the output voltage and output current; Determine whether the output power of the current period is greater than or equal to the marked maximum power; When the output power of the current period is less than the marked maximum power, performing a first preset number of disturbances in a sawtooth-shaped fluctuation between the first disturbance state, the second disturbance state, and the third disturbance state according to a preset step size, and obtaining the input voltage, output voltage, and output current of each disturbance, and obtaining the maximum output power and the minimum output power during the first disturbance period; Adjusting the preset step size based on the relationship between the maximum output power and the minimum output power or the relationship between the maximum output power and the marked maximum power; According to the adjusted step size and the relationship between the maximum output power and the marked maximum power, disturbances are performed for a preset number of disturbance periods, and the maximum output power during the disturbance is obtained as the new marked maximum power, and the maximum power point voltage is the input voltage after the disturbance.

2. The method according to claim 1, characterized in that When the output power of the current period is less than the marked maximum power, performing a first preset number of disturbances in a sawtooth-shaped fluctuation between the first disturbance state, the second disturbance state, and the third disturbance state according to a preset step size, including: When the output power of the current period is less than the marked maximum power, the system enters a first disturbance state, controlling the input voltage or the voltage reference value to increase by a preset step size, where the voltage reference value is a given voltage value in fixed voltage maximum power point tracking; Determine whether the increased input voltage or voltage reference value is greater than the disturbance upper limit of this disturbance process; When it is not greater than the upper disturbance limit, the input voltage or voltage reference value is continued to be controlled to increase by the preset step size, and the number of disturbances increases by 1 each time it increases; When the voltage is greater than the upper disturbance limit, the second disturbance state is entered, and the input voltage or the voltage reference value is controlled to decrease in a preset step size; Determine whether the decreasing input voltage or voltage reference value is less than the disturbance lower limit of this disturbance process; When the value is not less than the lower limit of the disturbance, the input voltage or voltage reference value is continuously controlled to decrease by the preset step size, and the number of disturbances increases by 1 each time it decreases; When the voltage is less than the lower disturbance limit, the system enters the third disturbance state and controls the input voltage or the voltage reference value to increase by a preset step size. Determine whether the increased input voltage or voltage reference value is greater than the output voltage; When it is not greater than the output voltage, the input voltage or the voltage reference value is continued to be controlled to increase by a preset step size, and the number of disturbances increases by 1 each time the step size is increased; When it is greater than the output voltage, it enters the first disturbance state and repeats the above process until the number of disturbances reaches the first preset number.

3. The method according to claim 2, characterized in that The upper limit of the disturbance in this disturbance process is the sum of the output voltage of the previous disturbance process and ten times the preset step length, and the lower limit of the disturbance in this disturbance process is the difference between the output voltage of the previous disturbance process and ten times the preset step length.

4. The method according to claim 1, wherein Adjusting the preset step size based on the relationship between the maximum output power and the minimum output power or the relationship between the maximum output power and the marked maximum power includes: Calculating a first difference between the maximum output power and the minimum output power or a second difference between the maximum output power and the marked maximum power; When the first difference is greater than a third preset value or the second difference is greater than a fifth preset value, the preset step size remains unchanged; When the first difference is less than or equal to the third preset value and greater than the fourth preset value, or the second difference is less than the fifth preset value or greater than the sixth preset value, the preset step size is adjusted to the second preset step size; When the first difference is less than or equal to the fourth preset value or the second difference is less than or equal to the sixth preset value, the preset step size is adjusted to the third preset step size, the third preset value is greater than the fourth preset value, the fifth preset value is greater than the sixth preset value, the preset step size is greater than the second preset step size, and the second preset step size is greater than the third preset step size.

5. The method according to claim 1, characterized in that Perform disturbances during the preset number of disturbances according to the adjusted step size and the relationship between the maximum output power and the marked maximum power, and obtain the maximum output power during the disturbance as the new marked maximum power. The maximum power point voltage is the input voltage after the disturbance, including: When the maximum output power is greater than or equal to the marked maximum power, the maximum output power is used as the marked maximum power, and the output power determination, judgment, and disturbance process during the disturbance are repeated until the preset number of disturbance periods is reached. The maximum output power during the disturbance is obtained as the new marked maximum power, and the maximum power point voltage is the input voltage after the disturbance; When the maximum output power is less than the marked maximum power, the marked maximum power is kept unchanged, and the output power determination, judgment and disturbance process during the disturbance period are repeated until the preset number of disturbance periods is reached. The maximum output power during the disturbance is obtained as the new marked maximum power, and the maximum power point voltage is the input voltage after the disturbance.

6. The method according to claim 1, characterized in that The method further comprises: When the output power of the current period is greater than or equal to the marked maximum power, the output power of the current period is used as the marked maximum power point, and the maximum power point voltage is the output voltage of the current period.

7. The method according to claim 1, characterized in that Before obtaining the input voltage, output voltage, and output current of the photovoltaic system in the current period and determining the output power in the current period based on the output voltage and output current, the method further includes: Determine whether the photovoltaic system is in aging mode; When in the aging mode, the maximum power point voltage is fixed to a preset maximum power point voltage.

8. A maximum power point tracking device for a photovoltaic system, characterized in that: The device comprises: A parameter acquisition module is used to obtain the input voltage, output voltage and output current of the photovoltaic system in the current period, and determine the output power of the current period based on the output voltage and output current; A judgment module, used to judge whether the output power of the current period is greater than or equal to the marked maximum power; a disturbance module, configured to, when the output power of the current period is less than the marked maximum power, perform disturbances for a first preset number of times in a sawtooth-shaped fluctuation between a first disturbance state, a second disturbance state, and a third disturbance state according to a preset step size, and obtain the input voltage, output voltage, and output current of each disturbance, and obtain the maximum output power and the minimum output power during the first disturbance period; a step size adjustment module, configured to adjust a preset step size based on a relationship between a maximum output power and a minimum output power or a relationship between a maximum output power and a marked maximum power; The maximum power point determination module performs disturbances during a preset number of disturbances according to the adjusted step size and the relationship between the maximum output power and the marked maximum power, and obtains the maximum output power during the disturbance as the new marked maximum power. The maximum power point voltage is the input voltage after the disturbance.

9. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the maximum power point tracking method for a photovoltaic system according to any one of claims 1 to 7 by executing the computer instructions.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the maximum power point tracking method for a photovoltaic system according to any one of claims 1 to 7.

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