A maximum power point tracking method and a photovoltaic system

Abstract

This invention discloses a maximum power point tracking (MPPT) method and a photovoltaic system. The method includes: adjusting an initial voltage value based on a preset step size to obtain a first voltage value; updating an initial adjustment parameter based on the voltage adjustment direction and a first preset value to obtain a first adjustment parameter; the preset step size is determined based on the absolute value of the initial adjustment parameter; obtaining the adjusted first power value; if the first power value is not the maximum power point, decreasing the absolute value of the first adjustment parameter based on a second preset value to obtain a second adjustment parameter; the second preset value is less than the first preset value; determining the voltage adjustment direction in the next voltage adjustment strategy based on the first power value and the initial power value; using the first voltage value as the initial voltage value, the first power value as the initial power value, and the second adjustment parameter as the initial adjustment parameter, and executing the voltage adjustment strategy again until the maximum power point is tracked. This invention improves the maximum power point tracking performance.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic inverter technology, and in particular to a maximum power point tracking method and a photovoltaic system. Background Technology

[0002] When a photovoltaic system is in operation, its maximum power will change dynamically with conditions such as light intensity, temperature, and load. If maximum power point tracking is not performed, the photovoltaic inverter system may operate at a non-maximum power point, resulting in energy waste.

[0003] The perturbation-observation method is a commonly used maximum power point tracking (MPPT) method. It involves periodically perturbing the voltage of a photovoltaic (PV) inverter system and comparing the power output before and after the perturbation. Ultimately, the perturbation-observation method will continuously perturb the system near the maximum power point with a perturbation step size. A large perturbation step size results in low tracking accuracy, while a small perturbation step size results in slow tracking speed; neither can be achieved simultaneously. Summary of the Invention

[0004] This invention provides a maximum power point tracking method and a photovoltaic system to solve the problem of poor maximum power point tracking performance.

[0005] According to one aspect of the present invention, a maximum power point tracking method is provided, applied to a photovoltaic system, comprising: Obtain the initial voltage and initial power values ​​of the photovoltaic system; A voltage adjustment strategy is executed based on the initial voltage value, the initial power value, the initial adjustment parameters, and the preset step size value; The voltage adjustment strategy includes: The initial voltage value is adjusted based on a preset step size to obtain a first voltage value. The initial adjustment parameter is then updated based on the voltage adjustment direction of the initial voltage value and a first preset value to obtain a first adjustment parameter. The update direction of the initial adjustment parameter is the same as the voltage adjustment direction. The preset step size is determined based on the absolute value of the initial adjustment parameter. Obtain the adjusted first power value; If the first power value is not the maximum power point, the absolute value of the first adjustment parameter is reduced by the second preset value to obtain the second adjustment parameter; the second preset value is less than the first preset value. The voltage adjustment direction in the next voltage adjustment strategy is determined based on the first power value and the initial power value. Using the first voltage value as the initial voltage value, the first power value as the initial power value, and the second adjustment parameter as the initial adjustment parameter, the voltage adjustment strategy is executed again until the maximum power point is tracked.

[0006] Optionally, adjusting the initial voltage value based on a preset step size to obtain a first voltage value includes: The first voltage value is obtained by increasing or decreasing a preset step size value based on the initial voltage value; The step of updating the initial adjustment parameters based on the voltage adjustment direction and a first preset value to obtain the first adjustment parameters includes: The first adjustment parameter is obtained by increasing or decreasing the first preset value based on the initial adjustment parameter.

[0007] Optionally, the preset step size value is determined based on the absolute value of the initial adjustment parameter, including: When the absolute value of the initial adjustment parameter is within a first range, the preset step size value is determined based on a first preset function; When the absolute value of the initial adjustment parameter is within the second range, the preset step size value is determined based on the second preset function; When the absolute value of the initial adjustment parameter is within the third range, the preset step size value is determined based on the third preset function; When the absolute value of the initial adjustment parameter is within the fourth range, the preset step size value is determined based on the fourth preset function; The first range, the second range, the third range, and the fourth range are four consecutive numerical intervals that do not contain each other, and the values ​​in the first range, the second range, the third range, and the fourth range increase sequentially.

[0008] Optionally, when the absolute value of the initial adjustment parameter is within a first range, the preset step size value decreases at a first speed based on the first preset function; When the absolute value of the initial adjustment parameter is within the second range, the preset step size value decreases at a second speed based on the second preset function; the first speed is less than the second speed. When the absolute value of the initial adjustment parameter is in the third range, the preset step size value increases at a third speed based on the first preset function; When the absolute value of the initial adjustment parameter is in the fourth range, the preset step size value decreases at a fourth speed based on the second preset function; the third speed is less than the fourth speed.

[0009] Optionally, the voltage regulation strategy further includes: If the first power value was greater than the initial power value after the last execution of the voltage adjustment strategy, and the first power value is less than the initial power value after the current execution of the voltage adjustment strategy, then it is determined that the maximum power point was tracked after the last execution of the voltage adjustment strategy.

[0010] Optionally, after locating the maximum power point, the voltage regulation strategy further includes: If the absolute value of the initial adjustment parameter is not within the first range, the voltage adjustment strategy is executed again.

[0011] Optionally, determining the voltage adjustment direction in the next voltage adjustment strategy based on the first power value and the initial power value includes: If the first power value is less than the initial power value, the voltage adjustment direction in the next voltage adjustment strategy is opposite to the voltage adjustment direction in the current voltage adjustment strategy; If the first power value is greater than the initial power value, the voltage adjustment direction in the next voltage adjustment strategy is the same as the voltage adjustment direction in the current voltage adjustment strategy.

[0012] Optionally, obtaining the adjusted first power value includes: Within a first time period, the power values ​​of multiple photovoltaic systems are acquired at intervals; The average power value of each photovoltaic system is calculated to obtain the first power value.

[0013] Optionally, if the first power value is not the maximum power point, the step of reducing the absolute value of the first adjustment parameter based on a second preset value to obtain the second adjustment parameter includes: If the first power value is not the maximum power point and the first adjustment parameter is positive, reduce the first adjustment parameter by the second preset value to obtain the second adjustment parameter; If the first power value is not the maximum power point and the first adjustment parameter is negative, increase the first adjustment parameter by the second preset value to obtain the second adjustment parameter.

[0014] According to another aspect of the present invention, a photovoltaic system is provided, including a controller, a photovoltaic inverter, and a photovoltaic module, wherein the photovoltaic module is connected to the photovoltaic inverter, the controller is connected to the photovoltaic inverter, the photovoltaic inverter is used to supply power to a load, and the controller is used to execute the maximum power point tracking method described in any embodiment of the present invention.

[0015] The technical solution provided by this invention detects power changes in a photovoltaic system and updates the preset step size and initial voltage value in real time. This allows the photovoltaic system to continuously increase the adjustment of the initial voltage value before reaching maximum power, thereby improving the tracking speed to the maximum power point. Conversely, once maximum power is reached, the adjustment of the initial voltage value is continuously decreased, thus improving the tracking accuracy to the maximum power point. Therefore, this invention offers flexible tracking of the maximum power point, achieving real-time, rapid, and accurate tracking of the photovoltaic system's maximum power point, resulting in excellent tracking performance.

[0016] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of a voltage adjustment strategy provided according to an embodiment of the present invention; Figure 2 This is a flowchart of another voltage adjustment strategy provided by an embodiment of the present invention; Figure 3 This is a flowchart of another voltage regulation strategy provided according to an embodiment of the present invention. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0020] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0021] This invention provides a maximum power point tracking (MPPT) method. The MPPT method is applied to a photovoltaic (PV) system and includes: acquiring the initial voltage and initial power values ​​of the PV system; and executing a voltage adjustment strategy based on the initial voltage, initial power, adjustment parameters, and step size. Figure 1 A flowchart illustrating a voltage regulation strategy provided in an embodiment of the present invention. (Reference) Figure 1 Voltage regulation strategies include: S110. Adjust the initial voltage value based on the preset step size value to obtain the first voltage value, and update the initial adjustment parameter based on the voltage adjustment direction of the initial voltage value and the first preset value to obtain the first adjustment parameter; the update direction of the initial adjustment parameter is the same as the voltage adjustment direction; the preset step size value is determined based on the absolute value of the initial adjustment parameter.

[0022] By increasing or decreasing the initial voltage value of the photovoltaic system, the power of the photovoltaic system can be controlled to change. Therefore, by continuously adjusting the initial voltage value of the photovoltaic system and detecting the changes in the power of the photovoltaic system, the power of the photovoltaic system can be controlled to gradually track the maximum power.

[0023] Specifically, when adjusting the power of a photovoltaic system, the initial voltage value can be increased or decreased by a preset step value. After the initial voltage value is adjusted, the initial adjustment parameters are updated. For example, if the initial voltage value is increased by a preset step value to obtain a first voltage value, the initial adjustment parameters are increased by a first preset value to obtain a first adjustment parameter. If the initial voltage value is decreased by a preset step value to obtain a first voltage value, the initial adjustment parameters are decreased by a first preset value to obtain the first adjustment parameter.

[0024] S120, Obtain the adjusted first power value.

[0025] In this process, the power output of the photovoltaic system changes after the initial voltage value is adjusted. By detecting the power output of the photovoltaic system, the change in the first power value after adjusting the initial voltage value is determined, thus continuously tracking towards the maximum power point.

[0026] S130. If the first power value is not the maximum power point, the absolute value of the first adjustment parameter is reduced based on the second preset value to obtain the second adjustment parameter; the second preset value is less than the first preset value.

[0027] If the first power value is greater than the power before adjustment, it means that the power of the photovoltaic system is in a phase of gradual increase. The photovoltaic system may not have reached the maximum power point. The power of the photovoltaic system can be increased again by adjusting the initial voltage value in the next adjustment.

[0028] If the first power value is less than the initial power value before adjustment, it indicates that the photovoltaic system has reached the maximum power point, and the maximum power point is between the first power value and the initial power value.

[0029] S140. Determine the voltage adjustment direction in the next voltage adjustment strategy based on the first power value and the initial power value.

[0030] For example, after increasing the initial voltage value by a preset step size, if the first power value increases compared to the initial power value, the initial voltage value continues to increase; if the first power value decreases compared to the initial power value, the initial voltage value decreases. Conversely, if decreasing the initial voltage value by a preset step size results in an increase in the first power value compared to the initial power value, the initial voltage value continues to decrease; if the first power value decreases compared to the initial power value, the initial voltage value increases. This configuration allows the first power value of the photovoltaic system to be controlled to continuously increase.

[0031] S150. Using the first voltage value as the initial voltage value, the first power value as the initial power value, and the second adjustment parameter as the initial adjustment parameter, the voltage adjustment strategy is executed again until the maximum power point is tracked.

[0032] Specifically, after executing a voltage adjustment strategy, if the maximum power point is not tracked, the first voltage value, the first power value, and the second adjustment parameter should be updated to the initial adjustment parameter after this adjustment, and the voltage adjustment strategy should continue to be executed to track the maximum power point.

[0033] If the maximum power point is not found this time, the absolute value of the first adjustment parameter needs to be reduced by the second preset value to obtain the second adjustment parameter.

[0034] For example, if the initial voltage value is continuously increased (or decreased) by a preset step size, and the first power value is continuously increasing relative to the initial power value, it indicates that the photovoltaic system has not reached its maximum power point. At this time, the initial adjustment parameter will also continuously increase (or decrease) by a first preset value to obtain a first adjustment parameter, and the absolute value of the first adjustment parameter will decrease by a second preset value to obtain a second adjustment parameter. Because the second preset value is less than the first preset value, the initial adjustment parameter in the next execution of the voltage adjustment strategy will still remain in an increasing (or decreasing) state compared to the initial adjustment parameter in the current execution of the voltage adjustment strategy.

[0035] After updating the second adjustment parameter to the initial adjustment parameter, the preset step size is determined based on the absolute value of the initial adjustment parameter. The preset step size can be set to gradually increase as the initial adjustment parameter increases. Thus, the larger the absolute value of the initial adjustment parameter, the larger the preset step size. This means that the preset step size for the next increase (or decrease) in the initial voltage of the photovoltaic system will be larger, and the power regulation of the photovoltaic system will increase synchronously, allowing the photovoltaic system to track its maximum power point more quickly.

[0036] When the initial voltage value is continuously increased (or decreased) by a preset step size, and the first power value decreases compared to the initial power value, it indicates that the maximum power point of the photovoltaic system is between the initial power value and the first power value. At this point, if the voltage adjustment strategy continues, the difference between the first power value and the initial power value will fluctuate between positive and negative. Therefore, the initial voltage value will fluctuate between increasing and decreasing the preset step size, and the initial adjustment parameter will continuously increase or decrease the first preset value until the first adjustment parameter tends to stabilize. However, by adjusting the first adjustment parameter with a second preset value, the absolute value of the first adjustment parameter will continuously decrease by the second preset value to obtain the second adjustment parameter. The second adjustment parameter will gradually approach 0, and the updated initial adjustment parameter will also gradually approach 0. Furthermore, the preset step size is determined based on the absolute value of the initial adjustment parameter. The preset step size can be set to gradually decrease as the absolute value of the initial adjustment parameter decreases. Thus, as the initial adjustment parameter approaches zero, its absolute value also gradually decreases. Consequently, the preset step size for the next increase (or decrease) in the initial voltage of the photovoltaic system will be even smaller, and the adjustment amount of the photovoltaic system to power will decrease synchronously, slowing down the rate of change in the photovoltaic system's power. Therefore, during the tracking of the maximum power point, the initial adjustment parameter will gradually approach zero, the voltage adjustment amplitude will become smaller, and the change in power value will become smaller, allowing for more accurate tracking of the maximum power point.

[0037] The technical solution provided by this invention detects power changes in a photovoltaic system and updates the preset step size and initial voltage value in real time. This allows the photovoltaic system to continuously increase the adjustment of the initial voltage value before reaching maximum power, thereby improving the tracking speed to the maximum power point. Conversely, once maximum power is reached, the adjustment of the initial voltage value is continuously decreased, thus improving the tracking accuracy to the maximum power point. Therefore, this invention offers flexible tracking of the maximum power point, achieving real-time, rapid, and accurate tracking of the photovoltaic system's maximum power point, resulting in excellent tracking performance.

[0038] Figure 2 A flowchart illustrating another voltage regulation strategy provided in an embodiment of the present invention. (See reference...) Figure 2Based on the above embodiments, optionally, the initial voltage value is adjusted based on a preset step size value to obtain a first voltage value, including: S111. Increase or decrease the preset step size value based on the initial voltage value to obtain the first voltage value.

[0039] The initial adjustment parameters are updated based on the voltage adjustment direction and the first preset value to obtain the first adjustment parameters, including: S112. Increase or decrease the first preset value based on the initial adjustment parameter to obtain the first adjustment parameter.

[0040] The initial voltage value can be changed in both positive and negative directions to control the increase or decrease of the photovoltaic system power. When the initial voltage value increases by a preset step value, the initial adjustment parameter simultaneously increases by a first preset value. When the initial voltage value decreases by a preset step value, the initial adjustment parameter simultaneously decreases by a first preset value.

[0041] Continue to refer to Figure 2 Based on the above embodiments, optionally, S140, determining the voltage adjustment direction in the next voltage adjustment strategy based on the first power value and the initial power value, includes: S141. If the first power value is less than the initial power value, the voltage adjustment direction in the next voltage adjustment strategy is opposite to the voltage adjustment direction in the current voltage adjustment strategy; if the first power value is greater than the initial power value, the voltage adjustment direction in the next voltage adjustment strategy is the same as the voltage adjustment direction in the current voltage adjustment strategy.

[0042] If the first power value is greater than the initial power value, it indicates that the first power value has not reached the maximum power point, and the power of the photovoltaic system is in an upward trend. At this time, by keeping the voltage adjustment direction unchanged, the continuous increase of the first power value can be controlled until the maximum power point is reached.

[0043] If the first power value is less than the initial power value, it indicates that the first power value may have reached the maximum power point, and the power of the photovoltaic system is in a decreasing state. At this time, by changing the voltage adjustment direction, the first power value can be controlled to change from a decreasing state to an increasing state, so that the first power value can continuously approach the maximum power point.

[0044] Continue to refer to Figure 2 Based on the above embodiments, optionally, in S130, if the first power value is not the maximum power point, the absolute value of the first adjustment parameter is reduced by a second preset value to obtain the second adjustment parameter; the second preset value being less than the first preset value includes: S131. If the first power value is not the maximum power point and the first adjustment parameter is positive, decrease the first adjustment parameter based on the second preset value to obtain the second adjustment parameter; if the first power value is not the maximum power point and the first adjustment parameter is negative, increase the first adjustment parameter based on the second preset value to obtain the second adjustment parameter.

[0045] If the maximum power point is not found, the absolute value of the first adjustment parameter needs to be reduced by a second preset value to obtain a second adjustment parameter, so that the magnitude of the second adjustment parameter is closer to 0 than the first adjustment parameter.

[0046] When the first adjustment parameter is positive, it needs to be reduced by the second preset value to obtain the second adjustment parameter. When the first adjustment parameter is negative, it needs to be increased by the second preset value to obtain the second adjustment parameter.

[0047] Specifically, after each execution of the voltage adjustment strategy, if the first adjustment parameter is not restricted, when the maximum power point is tracked, the initial adjustment parameter is a random value. If the absolute value of the initial adjustment parameter is too large, the preset step size is also large, and the change in the first power value compared to the initial power value is also large. In other words, the maximum power point has a large range, and the accuracy of the tracked maximum power point is poor.

[0048] Therefore, as the voltage adjustment strategy is continuously executed, the first power value will continuously approach the maximum power point. If the voltage adjustment strategy continues to be executed, the difference between the first power value and the initial power value will continuously fluctuate between positive and negative. At this time, the initial voltage value will fluctuate between increasing the preset step value and decreasing the preset step value. The initial adjustment parameter will also continuously increase or decrease the first preset value to make the first adjustment parameter tend to stabilize.

[0049] Furthermore, by reducing the absolute value of the first adjustment parameter, it can be ensured that the second adjustment parameter tends to approach 0 after each execution of the voltage adjustment strategy. When the voltage adjustment strategy is executed again, the absolute value of the initial adjustment parameter continues to decrease, the preset step size value also decreases synchronously, and the change in the first power value relative to the initial power value will gradually decrease, thereby continuously improving the tracking accuracy of the maximum power point.

[0050] This invention sets a second preset value, which is less than the first preset value. When the maximum power point is not tracked, the second preset value will not affect the overall direction of change of the initial adjustment parameters, and the photovoltaic system can still maintain its tracking towards the maximum power point. Furthermore, when the photovoltaic system approaches the maximum power point, the tracking accuracy of the maximum power point can be improved.

[0051] Continue to refer to Figure 2Based on the above embodiments, optionally, S120, obtaining the adjusted first power value includes: S121. Within a first time period, the power values ​​of multiple photovoltaic systems are acquired at intervals.

[0052] S122. Calculate the average power value of each photovoltaic system to obtain the first power value.

[0053] For example, the first time can be 1 second. By detecting the output voltage and output current of the photovoltaic system, the power value of the photovoltaic inverter system can be generated.

[0054] Specifically, during the first time interval when the initial voltage value of the photovoltaic system increases or decreases by a preset step size, multiple sampling points can be set. For example, a sampling point can be set every 20 milliseconds to sample the output voltage and output current. A total of 50 sampling points can be set within 1 second. The first power value is obtained by calculating the power of the 50 sampling points, that is, by averaging the power value of the photovoltaic system in the first time interval.

[0055] Based on the above embodiments, optionally, the preset step size value is determined based on the absolute value of the initial adjustment parameter, including: when the absolute value of the initial adjustment parameter is within a first range, determining the preset step size value based on a first preset function; when the absolute value of the initial adjustment parameter is within a second range, determining the preset step size value based on a second preset function; when the absolute value of the initial adjustment parameter is within a third range, determining the preset step size value based on a third preset function; and when the absolute value of the initial adjustment parameter is within a fourth range, determining the preset step size value based on a fourth preset function. Wherein, the first range, second range, third range, and fourth range are four consecutive numerical intervals that do not overlap, and the values ​​within the first range, second range, third range, and fourth range increase sequentially.

[0056] By setting four consecutive numerical zones, different preset step sizes can be set when the absolute value of the initial adjustment parameter is in different ranges.

[0057] Optionally, when the absolute value of the initial adjustment parameter is within a first range, the preset step size decreases at a first speed based on a first preset function. When the absolute value of the initial adjustment parameter is within a second range, the preset step size decreases at a second speed based on a second preset function; the first speed is less than the second speed. When the absolute value of the initial adjustment parameter is within a third range, the preset step size increases at a third speed based on a third preset function. When the absolute value of the initial adjustment parameter is within a fourth range, the preset step size increases at a fourth speed based on a fourth preset function; the third speed is less than the fourth speed.

[0058] For example, the first preset value can be 2, and the second preset value can be 1. The first range can be [0, 2). When the absolute value of the initial adjustment parameter is within the first range, the preset step value is updated to the previous preset step value × 0.5.

[0059] The second range can be [2, 5). When the absolute value of the initial adjustment parameter is within the second range, the preset step value is updated to the previous preset step value - 0.1.

[0060] The third range can be [5,8). When the absolute value of the initial adjustment parameter is in the third range, the preset step value is updated to the previous preset step value + 0.1.

[0061] The fourth range can be [8, 10]. When the absolute value of the initial adjustment parameter is in the fourth range, the preset step value is updated to the previous preset step value × 2.

[0062] To ensure that the initial adjustment parameter does not increase uncontrollably, the maximum absolute value of the initial adjustment parameter can be limited to 10, and the initial voltage value can be limited to the range of [0.1, 2]. When the initial adjustment parameter exceeds 10, it should be set to 10. Furthermore, the initial voltage value cannot increase or decrease indefinitely. When executing the voltage adjustment strategy for the first time, the initial adjustment parameter can be 0, and the initial voltage value can be 2.

[0063] Therefore, it can be seen that the smaller the absolute value of the initial adjustment parameter, the smaller the preset step size, and the smaller the adjustment amount of the initial voltage value. Conversely, the larger the absolute value of the initial adjustment parameter, the larger the preset step size, and the larger the adjustment amount of the initial voltage value.

[0064] Figure 3 A flowchart illustrating yet another voltage regulation strategy provided in an embodiment of the present invention. (See reference...) Figure 3 Based on the above embodiments, optionally, in S150, the voltage adjustment strategy is executed again using the first voltage value as the initial voltage value, the first power value as the initial power value, and the second adjustment parameter as the initial adjustment parameter, until the maximum power point is tracked. The voltage adjustment strategy further includes: S160. If the first power value was greater than the initial power value after the last execution of the voltage adjustment strategy, and the first power value is less than the initial power value after the current execution of the voltage adjustment strategy, then it is determined that the maximum power point was tracked after the last execution of the voltage adjustment strategy.

[0065] The voltage adjustment strategy is used to continuously increase the initial power value of the photovoltaic system, making it approach the maximum power point. When the initial power value has not reached the maximum power point, the photovoltaic system continuously adjusts the power based on the initial voltage value. If, during the adjustment process, the initial power value changes from being greater than the initial power value to being less than the initial power value, it indicates that the photovoltaic system has reached the maximum power point, and the maximum power point is between the initial power value and the initial power value.

[0066] Continue to refer to Figure 3 Based on the above embodiments, optionally, in S160, if the first power value is greater than the initial power value after the previous execution of the voltage adjustment strategy, and the first power value is less than the initial power value after the current execution of the voltage adjustment strategy, then after determining that the maximum power point has been tracked after the previous execution of the voltage adjustment strategy, the voltage adjustment strategy further includes: S170: Determine if the absolute value of the initial adjustment parameter is within the first range. If not, execute the voltage adjustment strategy again. If yes, execute S180.

[0067] S180, Maximum power output point.

[0068] In this process, as the initial voltage value is continuously increased (or decreased) by a preset step size, and the first power value continuously increases relative to the initial power value, the absolute value of the initial adjustment parameter will also continuously increase and gradually move from the first range into the second, third, and fourth ranges. Therefore, the preset step size will also gradually increase. If the maximum power point is found at this point, the range between the first power value and the initial power value at which the maximum power point is located is also quite large. Therefore, it is necessary to continue tracking the maximum power point and reduce the range in which the maximum power point is located.

[0069] If the voltage adjustment strategy continues, the difference between the first power value and the initial power value will fluctuate between positive and negative. Therefore, the initial voltage value will fluctuate between increasing and decreasing the preset step size, and the initial adjustment parameter will continuously increase or decrease the first preset value to stabilize the first adjustment parameter. However, by adjusting the first adjustment parameter with the second preset value, the absolute value of the first adjustment parameter will continuously decrease to obtain the second adjustment parameter. The second adjustment parameter will gradually decrease, and the absolute value of the initial adjustment parameter will also continuously decrease, gradually moving from the fourth range to the third range, the second range, and the first range. Therefore, the preset step size will also gradually decrease. If the maximum power point is tracked in the first range, the maximum power point is located within a small range between the first power value and the initial power value. At this point, the maximum power point is more accurate, thus ensuring the reliability of the maximum power point tracking.

[0070] This invention also provides a photovoltaic system. It includes a controller, a photovoltaic inverter, and photovoltaic modules. The photovoltaic modules are connected to the photovoltaic inverter, and the controller is connected to the photovoltaic inverter. The photovoltaic inverter supplies power to a load, and the controller executes the maximum power point tracking method provided in any embodiment of this invention, which has similar beneficial effects and will not be described further.

[0071] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0072] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A maximum power point tracking method applied to a photovoltaic system, characterized in that, include: Obtain the initial voltage and initial power values ​​of the photovoltaic system; A voltage adjustment strategy is executed based on the initial voltage value, the initial power value, the initial adjustment parameters, and the preset step size value; The voltage adjustment strategy includes: The initial voltage value is adjusted based on a preset step size to obtain a first voltage value. The initial adjustment parameter is then updated based on the voltage adjustment direction of the initial voltage value and a first preset value to obtain a first adjustment parameter. The update direction of the initial adjustment parameter is the same as the voltage adjustment direction. The preset step size is determined based on the absolute value of the initial adjustment parameter. The preset step size is positively correlated with the absolute value of the initial adjustment parameter. Obtain the adjusted first power value; If the first power value is not the maximum power point, the absolute value of the first adjustment parameter is reduced by the second preset value to obtain the second adjustment parameter; the second preset value is less than the first preset value. The voltage adjustment direction in the next voltage adjustment strategy is determined based on the first power value and the initial power value. Using the first voltage value as the initial voltage value, the first power value as the initial power value, and the second adjustment parameter as the initial adjustment parameter, the voltage adjustment strategy is executed again until the maximum power point is tracked. If the first power value was greater than the initial power value after the last execution of the voltage adjustment strategy, and the first power value is less than the initial power value after the current execution of the voltage adjustment strategy, then it is determined that the maximum power point was tracked after the last execution of the voltage adjustment strategy.

2. The maximum power point tracking method according to claim 1, characterized in that, The step of adjusting the initial voltage value based on a preset step size to obtain a first voltage value includes: The first voltage value is obtained by increasing or decreasing a preset step size value based on the initial voltage value; The initial adjustment parameters are updated based on the voltage adjustment direction and the first preset value to obtain the first adjustment parameters, including: The first adjustment parameter is obtained by increasing or decreasing the first preset value based on the initial adjustment parameter.

3. The maximum power point tracking method according to claim 1, characterized in that, The preset step size value is determined based on the absolute value of the initial adjustment parameter, including: When the absolute value of the initial adjustment parameter is within a first range, the preset step size value is determined based on a first preset function; When the absolute value of the initial adjustment parameter is within the second range, the preset step size value is determined based on the second preset function; When the absolute value of the initial adjustment parameter is within the third range, the preset step size value is determined based on the third preset function; When the absolute value of the initial adjustment parameter is within the fourth range, the preset step size value is determined based on the fourth preset function; The first range, the second range, the third range, and the fourth range are four consecutive numerical intervals that do not contain each other, and the values ​​in the first range, the second range, the third range, and the fourth range increase sequentially.

4. The maximum power point tracking method according to claim 3, characterized in that, When the absolute value of the initial adjustment parameter is within a first range, the preset step size value decreases at a first speed based on the first preset function; When the absolute value of the initial adjustment parameter is within the second range, the preset step size value decreases at a second speed based on the second preset function; the first speed is less than the second speed. When the absolute value of the initial adjustment parameter is within the third range, the preset step size value increases at a third speed based on the third preset function; When the absolute value of the initial adjustment parameter is within the fourth range, the preset step size value increases at a fourth speed based on the fourth preset function; the third speed is less than the fourth speed.

5. The maximum power point tracking method according to claim 3, characterized in that, After locating the maximum power point, the voltage regulation strategy further includes: If the absolute value of the initial adjustment parameter is not within the first range, the voltage adjustment strategy is executed again.

6. The maximum power point tracking method according to claim 1, characterized in that, The step of determining the voltage adjustment direction in the next voltage adjustment strategy based on the first power value and the initial power value includes: If the first power value is less than the initial power value, the voltage adjustment direction in the next voltage adjustment strategy is opposite to the voltage adjustment direction in the current voltage adjustment strategy; If the first power value is greater than the initial power value, the voltage adjustment direction in the next voltage adjustment strategy is the same as the voltage adjustment direction in the current voltage adjustment strategy.

7. The maximum power point tracking method according to claim 1, characterized in that, The process of obtaining the adjusted first power value includes: Within a first time period, the power values ​​of multiple photovoltaic systems are acquired at intervals; The average power value of each photovoltaic system is calculated to obtain the first power value.

8. The maximum power point tracking method according to claim 1, characterized in that, If the first power value is not the maximum power point, the second adjustment parameter is obtained by reducing the absolute value of the first adjustment parameter based on the second preset value, including: If the first power value is not the maximum power point and the first adjustment parameter is positive, reduce the first adjustment parameter by the second preset value to obtain the second adjustment parameter; If the first power value is not the maximum power point and the first adjustment parameter is negative, increase the first adjustment parameter by the second preset value to obtain the second adjustment parameter.

9. A photovoltaic system, characterized in that, The device includes a controller, a photovoltaic inverter, and a photovoltaic module, wherein the photovoltaic module is connected to the photovoltaic inverter, the controller is connected to the photovoltaic inverter, the photovoltaic inverter is used to supply power to a load, and the controller is used to execute the maximum power point tracking method according to any one of claims 1-8.

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