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, first using measured voltage and the theoretical current corresponding to measured voltage to calculate first power, then based on the power, complete power evaluation based on voltage, and complete power evaluation based on current based on the same principle, finally based on twice evaluation results complete final evaluation, in the whole process, theoretical current and theoretical voltage are selected using current-voltage curve model, so that it can be guaranteed that the power calculated each time will be less than the power corresponding to maximum power point, ensure that final evaluation result will not exceed reasonable range.

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 contain errors. During testing, the DC power and charge collected by the simulator may deviate from the actual values, affecting the accuracy of the numerator. Secondly, due to control errors, the actual IV curve characteristics output by the simulator may not perfectly match the preset expected IV curve characteristics, potentially exhibiting offsets and distortions. This affects the accuracy of the denominator, ultimately leading to incorrect efficiency evaluation results exceeding 100%, thus impacting the overall evaluation outcome. Current methods primarily involve manually correcting the result back to within 100% when it exceeds this threshold. While this ensures the result stays within the normal range, it still cannot completely eliminate inaccuracies in the evaluation results. Summary of the Invention

[0006] This invention aims to address at least one of the technical problems existing in the prior art. To this end, this invention proposes a photovoltaic inverter MPPT efficiency evaluation method, which can solve the problems of low efficiency and inability to fully utilize the high sampling rate performance of ADCs in current multi-channel switching chip-based sampling methods.

[0007] This invention also proposes a photovoltaic inverter MPPT efficiency evaluation circuit, 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 theoretical current corresponding to the measured voltage is determined based on the measured voltage and 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 power is obtained based on the measured voltage and the theoretical current;

[0012] The first tracking efficiency is obtained based on the first power and the maximum power in the current-voltage curve model;

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

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

[0015] The second power is obtained based on the measured current and the theoretical voltage;

[0016] The second tracking efficiency is obtained based on the second power and the maximum power in the current-voltage curve model.

[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, a first power is calculated using the measured voltage and the theoretical current corresponding to the measured voltage. Then, a voltage-based power evaluation is performed based on this power, and a current-based power evaluation is performed based on the same principle. Finally, the final evaluation is completed based on the results of the two evaluations. Throughout the process, a current-voltage curve model is used to select theoretical current and theoretical voltage, thereby ensuring that the calculated power is always smaller than the power corresponding to the maximum power point, guaranteeing that the final evaluation result never exceeds a reasonable range. The MPPT efficiency evaluation method for photovoltaic inverters implemented in this invention solves the problem of exceeding the normal range during MPPT efficiency evaluation of photovoltaic inverters, ensuring that the evaluation results always remain within the normal range. This method has excellent industrial application significance and is suitable for industrial promotion.

[0020] 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:

[0021] Obtain a first weighting factor corresponding to the first tracking efficiency and a second weighting factor corresponding to the second tracking efficiency;

[0022] 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.

[0023] According to some embodiments of the present invention, the first weighting factor and the second weighting factor have the same magnitude.

[0024] 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:

[0025] 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.

[0026] 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.

[0027] According to some embodiments of the present invention, the photovoltaic inverter MPPT efficiency evaluation method further includes the following steps:

[0028] The measured voltage is continuously acquired, and the first power is calculated based on the measured voltage;

[0029] The first power is integrated within a preset integration time to obtain the first energy level;

[0030] The measured current is continuously acquired, and the second power is calculated based on the measured current.

[0031] The second power is integrated within the preset integration time to obtain the second electrical quantity.

[0032] The theoretical power corresponding to the maximum power point in the current-voltage curve model is integrated within the preset integration time to obtain the third electrical quantity;

[0033] The third tracking efficiency is obtained based on the first energy level and the third energy level.

[0034] The fourth tracking efficiency is obtained based on the second quantitative value and the third electrical quantity;

[0035] The second final MPPT efficiency result is obtained based on the third and fourth tracking efficiencies.

[0036] According to some embodiments of the present invention, obtaining the second final MPPT efficiency result based on the third tracking efficiency and the fourth tracking efficiency includes:

[0037] Obtain the third weighting factor corresponding to the third tracking efficiency and the fourth weighting factor corresponding to the fourth tracking efficiency;

[0038] The second final MPPT efficiency result is obtained based on the third tracking efficiency and the third weighting factor, the fourth tracking efficiency and the fourth weighting factor.

[0039] According to some embodiments of the present invention, the third weighting factor has the same magnitude as the fourth weighting factor.

[0040] According to some embodiments of the present invention, the magnitudes of the third weighting factor and the fourth weighting factor are obtained by the following steps:

[0041] 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.

[0042] The third weighting factor and the fourth 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.

[0043] A photovoltaic inverter MPPT efficiency evaluation system according to a second aspect of the present invention includes:

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

[0045] The theoretical current acquisition unit is used to determine the theoretical current corresponding to the measured voltage based on the measured voltage and a pre-acquired current-voltage curve model; wherein, the current-voltage curve model characterizes the theoretical output characteristics of the photovoltaic simulator;

[0046] The first power calculation unit is used to obtain the first power based on the measured voltage and the theoretical current;

[0047] The first tracking efficiency calculation unit is used to obtain the first tracking efficiency based on the first power and the maximum power in the current-voltage curve model;

[0048] The current acquisition unit is used to acquire the measured current output by the photovoltaic simulator;

[0049] The theoretical voltage acquisition unit is used to determine the theoretical voltage corresponding to the measured current based on the measured current and the current-voltage curve model.

[0050] The second power calculation unit is used to obtain the second power based on the measured current and the theoretical voltage;

[0051] The second tracking efficiency calculation unit is used to obtain the second tracking efficiency based on the second power and the maximum power in the current-voltage curve model.

[0052] 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.

[0053] The analog-to-digital conversion system according to embodiments of the present invention has at least the following beneficial effects:

[0054] 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, a first power is calculated using the measured voltage and the theoretical current corresponding to the measured voltage. Then, a voltage-based power evaluation is performed based on this power, and a current-based power evaluation is performed based on the same principle. Finally, the final evaluation is completed based on the results of the two evaluations. Throughout the process, a current-voltage curve model is used to select theoretical current and theoretical voltage, thereby ensuring that the calculated power is always smaller than the power corresponding to the maximum power point, guaranteeing that the final evaluation result never exceeds a reasonable range. 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 results always remain within the normal range. It has excellent industrial application significance and is suitable for industrial promotion.

[0055] 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.

[0056] 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

[0057] 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:

[0058] 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);

[0059] 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);

[0060] Figure 3 This is a flowchart of a photovoltaic inverter MPPT efficiency evaluation method according to an embodiment of the present invention;

[0061] Figure 4 This is a flowchart of a photovoltaic inverter MPPT efficiency evaluation method according to an embodiment of the present invention. Detailed Implementation

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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:

[0068] Obtain the measured voltage output from the photovoltaic simulator;

[0069] The theoretical current corresponding to the measured voltage is determined based on the measured voltage and the pre-acquired current-voltage curve model; wherein, the current-voltage curve model characterizes the theoretical output characteristics of the photovoltaic simulator.

[0070] The first power is obtained based on the measured voltage and theoretical current;

[0071] The first tracking efficiency is obtained based on the maximum power in the first power and current-voltage curve model;

[0072] Obtain the measured current output by the photovoltaic simulator;

[0073] The theoretical voltage corresponding to the measured current is determined based on the measured current and the current-voltage curve model.

[0074] The second power is obtained based on the measured current and theoretical voltage;

[0075] The second tracking efficiency is obtained based on the maximum power in the second power and current-voltage curve model.

[0076] The first final MPPT efficiency result is obtained based on the first tracking efficiency and the second tracking efficiency.

[0077] The output characteristic curve of the photovoltaic simulator can be referenced. Figure 1 , Figure 2 The current and voltage curves shown are derived from the output characteristic curve, which is a 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.

[0078] 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.

[0079] Specifically, when processing the measured voltage, first determine the theoretical current corresponding to the maximum power point in the current-voltage curve model and the measured voltage. Then, calculate the first power using the theoretical current and the measured voltage. Divide the first power by the maximum power in the current-voltage curve model to obtain the first tracking efficiency. It should be noted that the first power is obtained by multiplying the measured voltage and the theoretical current when calculating the first tracking efficiency. Therefore, it can be guaranteed that the first power will fall on the output characteristic curve, and the maximum power point in the output characteristic curve will necessarily be greater than the power of all other points in the output characteristic curve, ultimately ensuring that the first tracking efficiency will be less than 1.

[0080] When processing the measured current, first determine the theoretical voltage corresponding to the maximum power point in the current-voltage curve model. Then, calculate the second power using this theoretical voltage and the measured current. Divide this second power by the maximum power in the current-voltage curve model to obtain the second tracking efficiency. It should be noted that the second power is calculated by multiplying the measured current and the theoretical voltage. Therefore, it can be guaranteed that the second power will fall on the output characteristic curve, and the maximum power point in the output characteristic curve will necessarily be greater than the power of all other points on the output characteristic curve, ultimately ensuring that the second tracking efficiency will always be less than 1. It should also be noted that both the first and second tracking efficiencies are calculated by multiplying the measured value and the corresponding theoretical value; therefore, they can directly and effectively reflect the influence of the measured value on the efficiency.

[0081] 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.

[0082] 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, a first power is calculated using the measured voltage and the theoretical current corresponding to the measured voltage. Then, a voltage-based power evaluation is performed based on this power, and a current-based power evaluation is performed based on the same principle. Finally, the final evaluation is completed based on the results of the two evaluations. Throughout the process, a current-voltage curve model is used to select theoretical current and theoretical voltage, thereby ensuring that the calculated power is always smaller than the power corresponding to the maximum power point, guaranteeing that the final evaluation result never exceeds a reasonable range. The MPPT efficiency evaluation method for photovoltaic inverters implemented in this invention solves the problem of exceeding the normal range during MPPT efficiency evaluation of photovoltaic inverters, ensuring that the evaluation results always remain within the normal range. This method has excellent industrial application significance and is suitable for industrial promotion.

[0083] In some embodiments, obtaining a first final MPPT efficiency result based on a first tracking efficiency and a second tracking efficiency includes:

[0084] Obtain the first weighting factor corresponding to the first tracking efficiency and the second weighting factor corresponding to the second tracking efficiency;

[0085] 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.

[0086] 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.

[0087] 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.

[0088] In some embodiments, the magnitudes of the first weighting factor and the second weighting factor are obtained by the following steps:

[0089] 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.

[0090] 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.

[0091] 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.

[0092] refer to Figure 4 In some embodiments, the photovoltaic inverter MPPT efficiency evaluation method further includes the following steps:

[0093] Continuously acquire the measured voltage and calculate the first power based on the measured voltage;

[0094] The first power is integrated within a preset integration time to obtain the first energy level;

[0095] The measured current is continuously acquired, and the second power is calculated based on the measured current.

[0096] The second power is integrated within a preset integration time to obtain the second electrical quantity.

[0097] The theoretical power corresponding to the maximum power point in the current-voltage curve model is integrated within a preset integration time to obtain the third electrical quantity.

[0098] The third tracking efficiency is obtained based on the first and third charge levels.

[0099] The fourth tracking efficiency is obtained based on the second quantitative and the third electrical quantity.

[0100] The second final MPPT efficiency result is obtained based on the third and fourth tracking efficiencies.

[0101] In actual testing, the photovoltaic simulator will also change due to variations in its own characteristics. Therefore, directly determining the MPPT efficiency evaluation result of the photovoltaic inverter based on a single test result is prone to errors. This embodiment comprehensively considers this variation by using the power integral over time to obtain the energy. Specifically, the measured voltage is continuously collected, and the corresponding first power is calculated for each measured voltage. The integration is then performed within a preset integration time to obtain the first energy corresponding to the preset integration time. The measured current is continuously collected, and the corresponding second power is calculated for each measured voltage. The integration is then performed within a preset integration time to obtain the second energy corresponding to the preset integration time. Simultaneously, the theoretical power corresponding to the maximum power point in the current-voltage curve model is calculated and integrated within a preset integration time to obtain the third energy. The first and third energy values ​​are divided to determine the third tracking efficiency, and the second and third energy values ​​are used to determine the fourth tracking efficiency. Finally, the second and fourth tracking efficiencies are used to obtain the final MPPT efficiency result. Using integral calculations to determine the second final MPPT efficiency result effectively eliminates the influence of individual data with large errors compared to relying on a single calculation, thus yielding a more accurate second final MPPT efficiency result. It should be noted that the detection voltage and current are preferably detected within the same time period to further reduce the error in the evaluation results.

[0102] In some embodiments, a second final MPPT efficiency result is obtained based on a third tracking efficiency and a fourth tracking efficiency, including:

[0103] Obtain the third weighting factor corresponding to the third tracking efficiency and the fourth weighting factor corresponding to the fourth tracking efficiency;

[0104] The second final MPPT efficiency result is obtained based on the third tracking efficiency and the third weighting factor, the fourth tracking efficiency and the fourth weighting factor.

[0105] In actual testing, the impact of current and voltage on the final result will vary depending on the characteristic curve or different segments of the characteristic curve. Therefore, weights can be pre-assigned to different characteristic curves. After determining the characteristic curves, the corresponding third and fourth weighting factors are selected to calculate the final MPPT efficiency result. It is understood that when testing under the same conditions, the third and fourth weighting factors are the same as the first and second weighting factors.

[0106] In some embodiments, the third weighting factor and the fourth 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.

[0107] In some embodiments, the magnitudes of the third weighting factor and the fourth weighting factor are obtained by the following steps:

[0108] 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.

[0109] The third and fourth 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.

[0110] 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.

[0111] This invention also proposes a photovoltaic inverter MPPT efficiency evaluation system, which includes:

[0112] The voltage acquisition unit is used to acquire the measured voltage output by the photovoltaic simulator;

[0113] The theoretical current acquisition unit is used to determine the theoretical current corresponding to the measured voltage based on the measured voltage and the pre-acquired current-voltage curve model; wherein, the current-voltage curve model characterizes the theoretical output characteristics of the photovoltaic simulator;

[0114] The first power calculation unit is used to obtain the first power based on the measured voltage and theoretical current.

[0115] The first tracking efficiency calculation unit is used to obtain the first tracking efficiency based on the maximum power in the first power and current-voltage curve model;

[0116] The current acquisition unit is used to acquire the measured current output by the photovoltaic simulator;

[0117] The theoretical voltage acquisition unit is used to determine the theoretical voltage corresponding to the measured current based on the measured current and the current-voltage curve model.

[0118] The second power calculation unit is used to obtain the second power based on the measured current and theoretical voltage;

[0119] The second tracking efficiency calculation unit is used to obtain the second tracking efficiency based on the maximum power in the second power and current-voltage curve model.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] Specifically, when processing the measured voltage, first determine the theoretical current corresponding to the maximum power point in the current-voltage curve model and the measured voltage. Then, calculate the first power using the theoretical current and the measured voltage. Divide the first power by the maximum power in the current-voltage curve model to obtain the first tracking efficiency. It should be noted that the first power is obtained by multiplying the measured voltage and the theoretical current when calculating the first tracking efficiency. Therefore, it can be guaranteed that the first power will fall on the output characteristic curve, and the maximum power point in the output characteristic curve will necessarily be greater than the power of all other points in the output characteristic curve, ultimately ensuring that the first tracking efficiency will be less than 1.

[0124] When processing the measured current, first determine the theoretical voltage corresponding to the maximum power point in the current-voltage curve model. Then, calculate the second power using this theoretical voltage and the measured current. Divide this second power by the maximum power in the current-voltage curve model to obtain the second tracking efficiency. It should be noted that the second power is calculated by multiplying the measured current and the theoretical voltage. Therefore, it can be guaranteed that the second power will fall on the output characteristic curve, and the maximum power point in the output characteristic curve will necessarily be greater than the power of all other points on the output characteristic curve, ultimately ensuring that the second tracking efficiency will always be less than 1. It should also be noted that both the first and second tracking efficiencies are calculated by multiplying the measured value and the corresponding theoretical value; therefore, they can directly and effectively reflect the influence of the measured value on the efficiency.

[0125] 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.

[0126] 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, a first power is calculated using the measured voltage and the theoretical current corresponding to the measured voltage. Then, a voltage-based power evaluation is performed based on this power, and a current-based power evaluation is performed based on the same principle. Finally, the final evaluation is completed based on the results of the two evaluations. Throughout the process, a current-voltage curve model is used to select theoretical current and theoretical voltage, thereby ensuring that the calculated power is always smaller than the power corresponding to the maximum power point, guaranteeing that the final evaluation result never exceeds a reasonable range. 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 results always remain within the normal range. It has excellent industrial application significance and is suitable for industrial promotion.

[0127] 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.

[0128] 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.

[0129] 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 method for evaluating the MPPT efficiency of a photovoltaic inverter, characterized in that, include: Obtain the measured voltage output from the photovoltaic simulator; The theoretical current corresponding to the measured voltage is determined based on the measured voltage and the pre-acquired current-voltage curve model; wherein, the current-voltage curve model characterizes the theoretical output characteristics of the photovoltaic simulator. The first power is obtained based on the measured voltage and the theoretical current; The first tracking efficiency is obtained based on the first power and the maximum power in the current-voltage curve model; Obtain the measured current output by the photovoltaic simulator; The theoretical voltage corresponding to the measured current is determined based on the measured current and the current-voltage curve model. The second power is obtained based on the measured current and the theoretical voltage; The second tracking efficiency is obtained based on the second power and the maximum power in the current-voltage curve model; The first final MPPT efficiency result is obtained based on the first tracking efficiency and the second tracking efficiency.

2. The photovoltaic inverter MPPT efficiency evaluation method according to claim 1, characterized in that, 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.

3. The photovoltaic inverter MPPT efficiency evaluation method according to claim 2, characterized in that, The first weighting factor has the same magnitude as the second weighting factor.

4. 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.

5. The photovoltaic inverter MPPT efficiency evaluation method according to claim 1, characterized in that, It also includes the following steps: The measured voltage is continuously acquired, and the first power is calculated based on the measured voltage; The first power is integrated within a preset integration time to obtain the first energy level; The measured current is continuously acquired, and the second power is calculated based on the measured current. The second power is integrated within the preset integration time to obtain the second electrical quantity. The theoretical power corresponding to the maximum power point in the current-voltage curve model is integrated within the preset integration time to obtain the third electrical quantity. The third tracking efficiency is obtained based on the first energy level and the third energy level. The fourth tracking efficiency is obtained based on the second and third electrical quantities; The second final MPPT efficiency result is obtained based on the third and fourth tracking efficiencies.

6. The photovoltaic inverter MPPT efficiency evaluation method according to claim 5, characterized in that, The process of obtaining the second final MPPT efficiency result based on the third and fourth tracking efficiencies includes: Obtain the third weighting factor corresponding to the third tracking efficiency and the fourth weighting factor corresponding to the fourth tracking efficiency; The second final MPPT efficiency result is obtained based on the third tracking efficiency and the third weighting factor, the fourth tracking efficiency and the fourth weighting factor.

7. The photovoltaic inverter MPPT efficiency evaluation method according to claim 6, characterized in that, The third weighting factor has the same magnitude as the fourth weighting factor.

8. The photovoltaic inverter MPPT efficiency evaluation method according to claim 6, characterized in that, The magnitudes of the third weighting factor and the fourth 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 third weighting factor and the fourth 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.

9. 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 theoretical current acquisition unit is used to determine the theoretical current corresponding to the measured voltage based on the measured voltage and a pre-acquired current-voltage curve model; wherein, the current-voltage curve model characterizes the theoretical output characteristics of the photovoltaic simulator; The first power calculation unit is used to obtain the first power based on the measured voltage and the theoretical current; The first tracking efficiency calculation unit is used to obtain the first tracking efficiency based on the first power and the maximum power in the current-voltage curve model; The current acquisition unit is used to acquire the measured current output by the photovoltaic simulator; The theoretical voltage acquisition unit is used to determine the theoretical voltage corresponding to the measured current based on the measured current and the current-voltage curve model. The second power calculation unit is used to obtain the second power based on the measured current and the theoretical voltage; The second tracking efficiency calculation unit is used to obtain the second tracking efficiency based on the second power and the maximum power in the current-voltage curve model; 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.

10. 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 8.

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