Photovoltaic inverter mppt efficiency evaluation method and system, and storage medium

Abstract

The application discloses a kind of photovoltaic inverter MPPT efficiency evaluation method, system and storage medium, respectively to measured voltage and measured current are evaluated, then using the result of respective independent evaluation to determine final MPPT efficiency result, compared with the way of traditional direct calculation power then evaluation, effectively reduce the degree of being influenced by output error.And, in the process of processing respectively, by respectively to measured voltage and maximum power point corresponding voltage, to measured current and maximum power point corresponding current are calculated deviation, then using deviation calculation result to carry out tracking efficiency calculation mode, can directly fundamentally guarantee that final calculated result will be less than 100%, i.e., it is in reasonable range, and evaluation result also has real meaning, can effectively reflect the work of photovoltaic inverter.

Description

Technical Field

[0001] This invention relates to the field of photovoltaics, and in particular to a method, system, and storage medium for evaluating the MPPT efficiency of photovoltaic inverters. Background Technology

[0002] Photovoltaic power generation, as a clean energy source, plays a vital role in promoting energy transformation and ensuring power supply. The photovoltaic inverter is a crucial component of a photovoltaic power generation system, converting the direct current (DC) output from the photovoltaic array into alternating current (AC) for grid-connected consumption or off-grid use. The DC output characteristics of a photovoltaic array can be represented by an IV (current-voltage) curve. The shape and form of this curve are directly influenced by light intensity, temperature, and the material of the photovoltaic array. Any IV curve has one and only one maximum power point. When light intensity, temperature, or material changes, not only will the shape and form of the IV curve change, but the maximum power point will also change. During operation, the photovoltaic inverter needs to continuously locate and operate near the maximum power point of the photovoltaic array to ensure the photovoltaic power generation system outputs maximum power. This is the maximum power point tracking (MPPT) of the photovoltaic inverter.

[0003] Because actual photovoltaic arrays occupy a large area and are difficult to simulate in terms of light intensity and temperature, photovoltaic array simulators, which are lighter and easier to adjust, are often used in the production and testing of photovoltaic inverters. A photovoltaic array simulator is essentially a DC power supply device. It has a built-in photovoltaic array model through software algorithms and can simulate the DC output characteristics of an equivalent photovoltaic array based on set parameters such as light intensity, temperature, and material, thereby facilitating the MPPT efficiency test of photovoltaic inverters.

[0004] Based on a photovoltaic array simulator, the traditional MPPT efficiency calculation method mainly involves the photovoltaic array simulator collecting DC-side power as the numerator and using the maximum power point power of the IV curve simulated by the built-in model as the denominator. The efficiency is obtained by dividing the two. The maximum power point power is a theoretical value that represents the maximum power point of the simulated IV curve.

[0005] However, photovoltaic array simulators are electronic devices and therefore inherently subject to error. During testing, the DC power and charge collected by the simulator may deviate from the actual values, affecting the accuracy of the results. Secondly, due to the control of errors, the actual IV curve characteristics output by the simulator may not perfectly match the preset expected IV curve characteristics, potentially exhibiting deviations and distortions. This can lead to incorrect efficiency evaluation results exceeding 100%, thus impacting the overall evaluation outcome. Current methods primarily involve manually correcting the results back to within 100% when they exceed this threshold. While this ensures the results stay within the normal range, it still cannot completely eliminate the inaccuracy of the evaluation results. Summary of the Invention

[0006] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a method for evaluating the MPPT efficiency of photovoltaic inverters, which can solve the problem of MPPT efficiency exceeding the normal range during evaluation.

[0007] This invention also proposes a photovoltaic inverter MPPT efficiency evaluation system and storage medium.

[0008] The photovoltaic inverter MPPT efficiency evaluation method according to a first aspect of the present invention includes:

[0009] Obtain the measured voltage output from the photovoltaic simulator;

[0010] The voltage deviation is determined based on the measured voltage and the theoretical voltage corresponding to the maximum power point in the pre-acquired current-voltage curve model; wherein, the current-voltage curve model characterizes the theoretical output characteristics of the photovoltaic simulator.

[0011] The first efficiency loss ratio is determined based on the voltage deviation and the theoretical voltage corresponding to the maximum power point.

[0012] The first tracking efficiency is obtained based on the first efficiency loss ratio;

[0013] Obtain the measured current output by the photovoltaic simulator;

[0014] The current deviation is determined based on the measured current and the theoretical current corresponding to the maximum power point in the current-voltage curve model.

[0015] The second efficiency loss ratio is determined based on the current deviation and the theoretical current corresponding to the maximum power point.

[0016] The second tracking efficiency is obtained based on the second efficiency loss ratio;

[0017] The first final MPPT efficiency result is obtained based on the first tracking efficiency and the second tracking efficiency.

[0018] The photovoltaic inverter MPPT efficiency evaluation method according to embodiments of the present invention has at least the following beneficial effects:

[0019] The MPPT efficiency evaluation method for photovoltaic inverters implemented in this invention evaluates the efficiency of measured voltage and measured current separately, and then uses the results of each independent evaluation to determine the final MPPT efficiency result. Compared with the traditional method of directly calculating power and then evaluating, this effectively reduces the degree of influence from output errors. Furthermore, in the separate processing, by calculating the deviation between the measured voltage and the voltage corresponding to the maximum power point, and the measured current and the current corresponding to the maximum power point, and then using the deviation calculation results to track the efficiency calculation, it can be directly and fundamentally guaranteed that the final calculated result will always be less than 100%, that is, within a reasonable range, and the evaluation result also has true significance, effectively reflecting the operation of the photovoltaic inverter. The photovoltaic inverter MPPT efficiency evaluation method of this invention solves the problem of exceeding the normal range during the MPPT efficiency evaluation of photovoltaic inverters, ensuring that the evaluation result always remains within the normal range, possessing excellent industrial application significance, and suitable for industrial promotion.

[0020] According to some embodiments of the present invention, the photovoltaic inverter MPPT efficiency evaluation method further includes the following steps:

[0021] A first final MPPT efficiency result is obtained at each preset calculation time interval;

[0022] A second final MPPT efficiency result is obtained based on multiple first final MPPT efficiency results.

[0023] According to some embodiments of the present invention, obtaining a second final MPPT efficiency result based on a plurality of first final MPPT efficiency results includes:

[0024] The cumulative efficiency results are obtained by summing multiple first final MPPT efficiency results;

[0025] The second final MPPT efficiency result is obtained based on the accumulated efficiency result and the number of accumulations corresponding to the accumulated efficiency result.

[0026] According to some embodiments of the present invention, obtaining the first final MPPT efficiency result based on the first tracking efficiency and the second tracking efficiency includes:

[0027] Obtain a first weighting factor corresponding to the first tracking efficiency and a second weighting factor corresponding to the second tracking efficiency;

[0028] The first final MPPT efficiency result is obtained based on the first tracking efficiency and the first weighting factor, the second tracking efficiency and the second weighting factor.

[0029] According to some embodiments of the present invention, the first weighting factor and the second weighting factor have the same magnitude.

[0030] According to some embodiments of the present invention, the magnitudes of the first weighting factor and the second weighting factor are obtained by the following steps:

[0031] Based on the current-voltage curve model, a slow current change segment, a slow voltage change segment, a fast current change segment, and a fast voltage change segment are determined. In the slow current change segment, the current change rate is less than that in the fast current change segment, and in the slow voltage change segment, the voltage change rate is less than that in the fast voltage change segment.

[0032] The first weighting factor and the second weighting factor are determined based on the slow current change segment, the slow voltage change segment, the fast current change segment, and the fast voltage change segment.

[0033] According to some embodiments of the present invention, determining the first efficiency loss ratio based on the voltage deviation and the theoretical voltage corresponding to the maximum power point includes:

[0034] The intermediate loss ratio is obtained by subtracting the voltage deviation from the theoretical voltage corresponding to the maximum power point.

[0035] The absolute value of the intermediate loss ratio is calculated to obtain the first efficiency loss ratio.

[0036] According to some embodiments of the present invention, determining the second efficiency loss ratio based on the current deviation and the theoretical current corresponding to the maximum power point includes:

[0037] The intermediate loss ratio is obtained by subtracting the current deviation from the theoretical current corresponding to the maximum power point.

[0038] The second efficiency loss ratio is obtained by performing an absolute value operation on the intermediate loss ratio.

[0039] A photovoltaic inverter MPPT efficiency evaluation system according to a second aspect of the present invention includes:

[0040] The voltage acquisition unit is used to acquire the measured voltage output by the photovoltaic simulator;

[0041] The voltage deviation calculation unit is used to determine the voltage deviation based on the measured voltage and the theoretical voltage corresponding to the maximum power point in the pre-acquired current-voltage curve model; wherein, the current-voltage curve model characterizes the theoretical output characteristics of the photovoltaic simulator.

[0042] The first loss ratio calculation unit is used to determine the first efficiency loss ratio value based on the voltage deviation and the theoretical voltage corresponding to the maximum power point.

[0043] The first tracking efficiency calculation unit is used to obtain the first tracking efficiency based on the first efficiency loss ratio.

[0044] The current acquisition unit is used to acquire the measured current output by the photovoltaic simulator;

[0045] The current deviation calculation unit is used to determine the current deviation based on the measured current and the theoretical current corresponding to the maximum power point in the current-voltage curve model.

[0046] The second loss ratio calculation unit is used to determine the second efficiency loss ratio value based on the current deviation and the theoretical current corresponding to the maximum power point.

[0047] The second tracking efficiency calculation unit is used to obtain the second tracking efficiency based on the second efficiency loss ratio;

[0048] The result output unit is used to obtain a first final MPPT efficiency result based on the first tracking efficiency and the second tracking efficiency.

[0049] The analog-to-digital conversion system according to embodiments of the present invention has at least the following beneficial effects:

[0050] The MPPT efficiency evaluation system for photovoltaic inverters implemented in this invention evaluates the efficiency of measured voltage and measured current separately, and then uses the results of each independent evaluation to determine the final MPPT efficiency result. Compared with the traditional method of directly calculating power and then evaluating, this effectively reduces the degree of influence from output errors. Furthermore, in the separate processing, by calculating the deviation between the measured voltage and the voltage corresponding to the maximum power point, and the measured current and the current corresponding to the maximum power point, and then using the deviation calculation results to track the efficiency calculation, it can be directly and fundamentally guaranteed that the final calculated result will always be less than 100%, that is, within a reasonable range, and the evaluation result also has true significance, effectively reflecting the operation of the photovoltaic inverter. The photovoltaic inverter MPPT efficiency evaluation system of this invention solves the problem of exceeding the normal range during the MPPT efficiency evaluation of photovoltaic inverters, ensuring that the evaluation result always remains within the normal range, possessing excellent industrial application significance, and suitable for industrial promotion.

[0051] According to a third aspect embodiment of the present invention, a computer-readable storage medium stores computer-executable instructions for performing the photovoltaic inverter MPPT efficiency evaluation system method as described in the first aspect embodiment above. Since the computer-readable storage medium employs all the technical solutions of the photovoltaic inverter MPPT efficiency evaluation system method of the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0052] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0053] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0054] Figure 1 This is an output characteristic curve of a photovoltaic simulator according to an embodiment of the present invention (the actual output power does not deviate from the curve);

[0055] Figure 2 This is an output characteristic curve of a photovoltaic simulator according to an embodiment of the present invention (actual output power deviates from the curve);

[0056] Figure 3 This is a flowchart of a photovoltaic inverter MPPT efficiency evaluation method according to an embodiment of the present invention;

[0057] Figure 4 This is a flowchart of a photovoltaic inverter MPPT efficiency evaluation method according to an embodiment of the present invention. Detailed Implementation

[0058] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0059] In the description of this invention, the use of terms such as "first," "second," etc., is for the purpose of distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.

[0060] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0061] In the description of this invention, it should be noted that, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0062] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are some embodiments of the present invention, not all embodiments.

[0063] refer to Figure 3 This invention proposes a method for evaluating the MPPT efficiency of a photovoltaic inverter, which includes, but is not limited to, the following steps:

[0064] Obtain the measured voltage output from the photovoltaic simulator;

[0065] The voltage deviation is determined by comparing the measured voltage with the theoretical voltage corresponding to the maximum power point in the pre-acquired current-voltage curve model; whereby the current-voltage curve model characterizes the theoretical output characteristics of the photovoltaic simulator.

[0066] The first efficiency loss ratio is determined based on the voltage deviation and the theoretical voltage corresponding to the maximum power point.

[0067] The first tracking efficiency is obtained based on the first efficiency loss ratio;

[0068] Obtain the measured current output by the photovoltaic simulator;

[0069] The current deviation is determined based on the measured current and the theoretical current corresponding to the maximum power point in the current-voltage curve model.

[0070] The second efficiency loss ratio is determined based on the current deviation and the theoretical current corresponding to the maximum power point.

[0071] The second tracking efficiency is obtained based on the second efficiency loss ratio;

[0072] The first final MPPT efficiency result is obtained based on the first tracking efficiency and the second tracking efficiency.

[0073] The output characteristic curve of the photovoltaic simulator can be referenced. Figure 1 , Figure 2The current-voltage curve model shown is obtained from the output characteristic curve, which is the theoretical output curve. In actual output, the actual output result will deviate from the curve. This deviation may be above or below the curve. Therefore, it is very likely that the actual output power will be greater than the theoretical power corresponding to the maximum power point in the curve.

[0074] In this embodiment, the measured voltage and measured current are processed separately. The traditional method is to directly multiply the measured voltage and measured current to calculate the actual power. However, both measured voltage and measured current are measured values ​​and deviate from the theoretical values. Multiplying two values ​​with deviations will further amplify the error, or even increase it by an order of magnitude. By processing the measured voltage and measured current separately, the error in the final evaluation result can be effectively reduced because it eliminates the need to multiply the two error parameters.

[0075] Specifically, when processing the measured voltage, the voltage deviation between the measured voltage and the theoretical voltage corresponding to the maximum power point in the current-voltage curve model is first determined. This deviation is the actual voltage deviation, and whether it is positive or negative, it will affect the final efficiency result. This deviation can be understood as the voltage that will be lost later. This voltage deviation is then used to calculate the loss ratio, i.e., the first efficiency loss ratio. After obtaining the first loss ratio, subtracting this ratio from 1 yields the first tracking efficiency, i.e., the overall efficiency minus the lost efficiency, which is the final efficiency. It should be noted that this process can also be understood as the deviation between the power calculated by multiplying the measured voltage and the theoretical current corresponding to the maximum power point, and the power corresponding to the maximum power point. Because a ratio needs to be calculated ultimately, the parameter of the theoretical current corresponding to the same maximum power point is eliminated, resulting in the ratio between the voltage deviation between the measured voltage and the theoretical voltage corresponding to the maximum power point and the theoretical voltage corresponding to the maximum power point.

[0076] When processing the measured current, first determine the current deviation between the measured current and the theoretical current corresponding to the maximum power point in the current-voltage curve model. This deviation is the actual current deviation, and whether it is positive or negative, it will affect the final efficiency result. This deviation can be understood as the voltage and current that will be lost later. Further, use this current deviation to calculate this loss ratio, i.e., the second efficiency loss ratio. After obtaining the second loss ratio, directly subtract this ratio from 1 to obtain the second tracking efficiency. That is, the overall efficiency minus the efficiency that will be lost is the final efficiency. It should be noted that this process can also be understood as the deviation between the power calculated by multiplying the measured current and the theoretical voltage corresponding to the maximum power point, and the power corresponding to the maximum power point. Because a ratio needs to be calculated ultimately, the parameter of the theoretical voltage corresponding to the same maximum power point is eliminated, resulting in the ratio between the voltage deviation between the measured current and the theoretical current corresponding to the maximum power point and the theoretical current corresponding to the maximum power point.

[0077] After calculating the first and second tracking efficiencies, we can comprehensively consider the first and second tracking efficiencies, and further consider the influence of current and voltage on the actual evaluation results to obtain the final first MPPT efficiency result.

[0078] The MPPT efficiency evaluation method for photovoltaic inverters implemented in this invention evaluates the efficiency of measured voltage and measured current separately, and then uses the results of each independent evaluation to determine the final MPPT efficiency result. Compared with the traditional method of directly calculating power and then evaluating, this effectively reduces the degree of influence from output errors. Furthermore, in the separate processing, by calculating the deviation between the measured voltage and the voltage corresponding to the maximum power point, and the measured current and the current corresponding to the maximum power point, and then using the deviation calculation results to track the efficiency calculation, it can be directly and fundamentally guaranteed that the final calculated result will always be less than 100%, that is, within a reasonable range, and the evaluation result also has true significance, effectively reflecting the operation of the photovoltaic inverter. The photovoltaic inverter MPPT efficiency evaluation method of this invention solves the problem of exceeding the normal range during the MPPT efficiency evaluation of photovoltaic inverters, ensuring that the evaluation result always remains within the normal range, possessing excellent industrial application significance, and suitable for industrial promotion.

[0079] In some embodiments, the photovoltaic inverter MPPT efficiency evaluation method further includes the following steps:

[0080] A first final MPPT efficiency result is obtained at each preset calculation time interval;

[0081] The second final MPPT efficiency result is obtained based on multiple first final MPPT efficiency results.

[0082] In actual testing, the output of the photovoltaic simulator will also vary due to changes in its own characteristics. Therefore, if the MPPT efficiency evaluation result of the photovoltaic inverter is determined based on only a single test result, it is easy to introduce certain errors. In this embodiment, the first final MPPT efficiency result obtained from multiple measurements is averaged to obtain the second final MPPT efficiency result. Because multiple averaging is performed, errors can be effectively controlled, making the final second final MPPT efficiency result more accurate.

[0083] In some embodiments, a second final MPPT efficiency result is obtained based on multiple first final MPPT efficiency results, including:

[0084] The cumulative efficiency results are obtained by summing the first and final MPPT efficiency results.

[0085] The second final MPPT efficiency result is obtained based on the cumulative efficiency result and the number of accumulations corresponding to the cumulative efficiency result.

[0086] The second final MPPT efficiency result can be obtained directly by averaging and summing, which can effectively eliminate the influence of single measurement errors. In some embodiments, some erroneous points can be removed from the results of multiple calculations to further reduce errors.

[0087] In some embodiments, obtaining a first final MPPT efficiency result based on a first tracking efficiency and a second tracking efficiency includes:

[0088] Obtain the first weighting factor corresponding to the first tracking efficiency and the second weighting factor corresponding to the second tracking efficiency;

[0089] The first final MPPT efficiency result is obtained based on the first tracking efficiency and the first weighting factor, the second tracking efficiency and the second weighting factor.

[0090] In actual testing, the influence of current and voltage on the final result will be different for different characteristic curves or different sections of the characteristic curve. Therefore, the weights of different characteristic curves can be pre-assigned. After the characteristic curves are determined, the corresponding first weight factor and second weight factor are selected to complete the calculation of the final MPPT efficiency result.

[0091] In some embodiments, the magnitudes of the first weighting factor and the second weighting factor are the same. In this case, it is mainly considered that the influence of current and voltage on the final result is not significantly different, so no special processing is required, and the average can be calculated directly. It is understandable that if the weighting factors are selected in all cases, the preliminary preparation work can be simplified to some extent.

[0092] In some embodiments, the magnitudes of the first weighting factor and the second weighting factor are obtained by the following steps:

[0093] Based on the current-voltage curve model, the following segments are identified: slow current change segment, slow voltage change segment, fast current change segment, and fast voltage change segment. In the slow current change segment, the rate of current change is less than that in the fast current change segment, and in the slow voltage change segment, the rate of voltage change is less than that in the fast voltage change segment.

[0094] The first and second weighting factors are determined based on the slow current change segment, the slow voltage change segment, the fast current change segment, and the fast voltage change segment.

[0095] Generally, when the current changes faster than the voltage, the current has a greater impact; when the current changes slower than the voltage, the voltage has a greater impact. Based on this principle, weight allocation can be flexibly set, thereby further ensuring the accuracy of the final evaluation results.

[0096] In some embodiments, determining a first efficiency loss ratio based on the voltage deviation and the theoretical voltage corresponding to the maximum power point includes:

[0097] The intermediate loss ratio is obtained by subtracting the voltage deviation from the theoretical voltage corresponding to the maximum power point.

[0098] The absolute value of the intermediate loss ratio is calculated to obtain the first efficiency loss ratio.

[0099] Considering that the measured voltage may be higher than the theoretical voltage, and the directly calculated deviation would be negative in such cases, an absolute value calculation is performed to ensure that the result is always positive. It should be noted that both positive and negative deviations affect MPPT efficiency; therefore, the absolute value calculation is used directly to simplify the subsequent algorithm process.

[0100] In some embodiments, determining the second efficiency loss ratio based on the current deviation and the theoretical current corresponding to the maximum power point includes:

[0101] The intermediate loss ratio is obtained by subtracting the current deviation from the theoretical current corresponding to the maximum power point.

[0102] The second efficiency loss ratio is obtained by performing an absolute value operation on the intermediate loss ratio.

[0103] Considering that the measured current may exceed the theoretical current, and the directly calculated deviation would be negative in such cases, an absolute value calculation is performed to ensure the result is always positive. It should be noted that both positive and negative deviations affect MPPT efficiency; therefore, the absolute value calculation simplifies the subsequent algorithm process.

[0104] This invention also proposes a photovoltaic inverter MPPT efficiency evaluation system, which includes:

[0105] The voltage acquisition unit is used to acquire the measured voltage output by the photovoltaic simulator;

[0106] The voltage deviation calculation unit is used to determine the voltage deviation based on the measured voltage and the theoretical voltage corresponding to the maximum power point in the pre-acquired current-voltage curve model; wherein, the current-voltage curve model characterizes the theoretical output characteristics of the photovoltaic simulator.

[0107] The first loss ratio calculation unit is used to determine the first efficiency loss ratio based on the voltage deviation and the theoretical voltage corresponding to the maximum power point.

[0108] The first tracking efficiency calculation unit is used to obtain the first tracking efficiency based on the first efficiency loss ratio.

[0109] The current acquisition unit is used to acquire the measured current output by the photovoltaic simulator;

[0110] The current deviation calculation unit is used to determine the current deviation based on the measured current and the theoretical current corresponding to the maximum power point in the current-voltage curve model.

[0111] The second loss ratio calculation unit is used to determine the second efficiency loss ratio value based on the current deviation and the theoretical current corresponding to the maximum power point.

[0112] The second tracking efficiency calculation unit is used to obtain the second tracking efficiency based on the second efficiency loss ratio.

[0113] The result output unit is used to obtain the first final MPPT efficiency result based on the first tracking efficiency and the second tracking efficiency.

[0114] The output characteristic curve of the photovoltaic simulator can be referenced. Figure 1 , Figure 2 The current-voltage curve model shown is obtained from the output characteristic curve. This output characteristic curve is the theoretical output curve. In actual output, the actual output result will deviate from the curve. This deviation may be above or below the curve. Therefore, it is very likely that the actual output power will be greater than the power corresponding to the maximum power point in the curve.

[0115] In this embodiment, the measured voltage and measured current are processed separately. The traditional method is to directly multiply the measured voltage and measured current to calculate the actual power. However, both measured voltage and measured current are measured values ​​and deviate from the theoretical values. Multiplying two values ​​with deviations will further amplify the error, or even increase it by an order of magnitude. By processing the measured voltage and measured current separately, the error in the final evaluation result can be effectively reduced because it eliminates the need to multiply the two error parameters.

[0116] Specifically, when processing the measured voltage, the voltage deviation between the measured voltage and the theoretical voltage corresponding to the maximum power point in the current-voltage curve model is first determined. This deviation is the actual voltage deviation, and whether it is positive or negative, it will affect the final efficiency result. This deviation can be understood as the voltage that will be lost later. This voltage deviation is then used to calculate the loss ratio, i.e., the first efficiency loss ratio. After obtaining the first loss ratio, subtracting this ratio from 1 yields the first tracking efficiency, i.e., the overall efficiency minus the lost efficiency, which is the final efficiency. It should be noted that this process can also be understood as the deviation between the power calculated by multiplying the measured voltage and the theoretical current corresponding to the maximum power point, and the power corresponding to the maximum power point. Because a ratio needs to be calculated ultimately, the parameter of the theoretical current corresponding to the same maximum power point is eliminated, resulting in the ratio between the voltage deviation between the measured voltage and the theoretical voltage corresponding to the maximum power point and the theoretical voltage corresponding to the maximum power point.

[0117] When processing the measured current, first determine the current deviation between the measured current and the theoretical current corresponding to the maximum power point in the current-voltage curve model. This deviation is the actual current deviation, and whether it is positive or negative, it will affect the final efficiency result. This deviation can be understood as the voltage and current that will be lost later. Further, use this current deviation to calculate this loss ratio, i.e., the second efficiency loss ratio. After obtaining the second loss ratio, directly subtract this ratio from 1 to obtain the second tracking efficiency. That is, the overall efficiency minus the efficiency that will be lost is the final efficiency. It should be noted that this process can also be understood as the deviation between the power calculated by multiplying the measured current and the theoretical voltage corresponding to the maximum power point, and the power corresponding to the maximum power point. Because a ratio needs to be calculated ultimately, the parameter of the theoretical voltage corresponding to the same maximum power point is eliminated, resulting in the ratio between the voltage deviation between the measured current and the theoretical current corresponding to the maximum power point and the theoretical current corresponding to the maximum power point.

[0118] After calculating the first and second tracking efficiencies, we can comprehensively consider the first and second tracking efficiencies, and further consider the influence of current and voltage on the actual evaluation results to obtain the final first MPPT efficiency result.

[0119] The MPPT efficiency evaluation system for photovoltaic inverters implemented in this invention evaluates the efficiency of measured voltage and measured current separately, and then uses the results of each independent evaluation to determine the final MPPT efficiency result. Compared with the traditional method of directly calculating power and then evaluating, this effectively reduces the degree of influence from output errors. Furthermore, in the separate processing, by calculating the deviation between the measured voltage and the voltage corresponding to the maximum power point, and the measured current and the current corresponding to the maximum power point, and then using the deviation calculation results to track the efficiency calculation, it can be directly and fundamentally guaranteed that the final calculated result will always be less than 100%, that is, within a reasonable range, and the evaluation result also has true significance, effectively reflecting the operation of the photovoltaic inverter. The photovoltaic inverter MPPT efficiency evaluation system of this invention solves the problem of exceeding the normal range during the MPPT efficiency evaluation of photovoltaic inverters, ensuring that the evaluation result always remains within the normal range, possessing excellent industrial application significance, and suitable for industrial promotion.

[0120] Furthermore, one embodiment of the present invention provides a computer-readable storage medium storing computer-executable instructions that are executed by a processor or control unit, causing the processor to perform the photovoltaic inverter MPPT efficiency evaluation method described in the above embodiment.

[0121] It will be understood by those skilled in the art that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which may include computer storage media or non-transitory media and communication media or transient media. As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information such as computer-readable instructions, data structures, program modules, or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc DVD or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, as is known to those skilled in the art, communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0122] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A photovoltaic inverter MPPT efficiency evaluation method, characterized in that, include: Obtain the measured voltage output from the photovoltaic simulator; The voltage deviation is determined based on the measured voltage and the theoretical voltage corresponding to the maximum power point in the pre-acquired current-voltage curve model; wherein, the current-voltage curve model characterizes the theoretical output characteristics of the photovoltaic simulator. The first efficiency loss ratio is determined based on the voltage deviation and the theoretical voltage corresponding to the maximum power point. The first tracking efficiency is obtained based on the first efficiency loss ratio; Obtain the measured current output by the photovoltaic simulator; The current deviation is determined based on the measured current and the theoretical current corresponding to the maximum power point in the current-voltage curve model. The second efficiency loss ratio is determined based on the current deviation and the theoretical current corresponding to the maximum power point. The second tracking efficiency is obtained based on the second efficiency loss ratio; The first final MPPT efficiency result is obtained based on the first tracking efficiency and the second tracking efficiency; The step of obtaining the first final MPPT efficiency result based on the first tracking efficiency and the second tracking efficiency includes: Obtain a first weighting factor corresponding to the first tracking efficiency and a second weighting factor corresponding to the second tracking efficiency; The first final MPPT efficiency result is obtained based on the first tracking efficiency and the first weighting factor, the second tracking efficiency and the second weighting factor.

2. The photovoltaic inverter MPPT efficiency evaluation method according to claim 1, characterized in that, It also includes the following steps: A first final MPPT efficiency result is obtained at each preset calculation time interval; A second final MPPT efficiency result is obtained based on multiple first final MPPT efficiency results.

3. The photovoltaic inverter MPPT efficiency evaluation method according to claim 2, characterized in that, The step of obtaining the second final MPPT efficiency result based on multiple first final MPPT efficiency results includes: The cumulative efficiency results are obtained by summing multiple first final MPPT efficiency results; The second final MPPT efficiency result is obtained based on the accumulated efficiency result and the number of accumulations corresponding to the accumulated efficiency result.

4. The photovoltaic inverter MPPT efficiency evaluation method according to claim 3, characterized in that, The first weighting factor has the same magnitude as the second weighting factor.

5. The photovoltaic inverter MPPT efficiency evaluation method according to claim 3, characterized in that, The magnitudes of the first weighting factor and the second weighting factor are obtained through the following steps: Based on the current-voltage curve model, a slow current change segment, a slow voltage change segment, a fast current change segment, and a fast voltage change segment are determined. In the slow current change segment, the current change rate is less than that in the fast current change segment, and in the slow voltage change segment, the voltage change rate is less than that in the fast voltage change segment. The first weighting factor and the second weighting factor are determined based on the slow current change segment, the slow voltage change segment, the fast current change segment, and the fast voltage change segment.

6. A photovoltaic inverter MPPT efficiency evaluation system, characterized in that, include: The voltage acquisition unit is used to acquire the measured voltage output by the photovoltaic simulator; The voltage deviation calculation unit is used to determine the voltage deviation based on the measured voltage and the theoretical voltage corresponding to the maximum power point in the pre-acquired current-voltage curve model; wherein, the current-voltage curve model characterizes the theoretical output characteristics of the photovoltaic simulator. The first loss ratio calculation unit is used to determine the first efficiency loss ratio value based on the voltage deviation and the theoretical voltage corresponding to the maximum power point. The first tracking efficiency calculation unit is used to obtain the first tracking efficiency based on the first efficiency loss ratio. The current acquisition unit is used to acquire the measured current output by the photovoltaic simulator; The current deviation calculation unit is used to determine the current deviation based on the measured current and the theoretical current corresponding to the maximum power point in the current-voltage curve model. The second loss ratio calculation unit is used to determine the second efficiency loss ratio value based on the current deviation and the theoretical current corresponding to the maximum power point. The second tracking efficiency calculation unit is used to obtain the second tracking efficiency based on the second efficiency loss ratio; The result output unit is used to obtain a first final MPPT efficiency result based on the first tracking efficiency and the second tracking efficiency. The step of obtaining the first final MPPT efficiency result based on the first tracking efficiency and the second tracking efficiency includes: Obtain a first weighting factor corresponding to the first tracking efficiency and a second weighting factor corresponding to the second tracking efficiency; The first final MPPT efficiency result is obtained based on the first tracking efficiency and the first weighting factor, the second tracking efficiency and the second weighting factor.

7. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions for causing a computer to perform the photovoltaic inverter MPPT efficiency evaluation method as described in any one of claims 1 to 5.

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