Power generation monitoring method and system for photovoltaic panel

Abstract

The invention relates to the field of photovoltaic module detection, in particular to a power generation monitoring method and system for a photovoltaic panel, and the method comprises the steps: firstly obtaining the output current, the light receiving area, the inclination angle, the latitude and the time of a target photovoltaic panel, and then putting the light receiving area, the inclination angle, the latitude and the time into an expected current calculation model, and finally, according to the deviation between the output current and the expected current, evaluating the working condition of the target photovoltaic panel. Compared with the prior art, the method has the advantages that effective modeling association can be carried out on geographical and time factors influencing the illumination intensity, specific quantification is realized, the workload of professionals is reduced, and the problem of low accuracy of photovoltaic panel working condition evaluation in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic component detection, and more specifically, to a method and system for monitoring power generation of photovoltaic panels. Background Art

[0002] The IV curve test device is a device specially used to test the current-voltage (IV) relationship of photovoltaic panels and photovoltaic modules. It is mainly composed of a probe, an analog-to-digital conversion module, a host terminal and a touch screen. Its main working principle is: the probe is connected to the output end of the photovoltaic panel to receive the output current and voltage of the photovoltaic panel. The analog-to-digital conversion module converts the current signal and voltage signal into a digital signal for data processing, and converts the data processing result into an IV curve for professionals to evaluate the working condition of the photovoltaic panel. The traditional IV curve test device can only provide IV curves for professionals to evaluate the current working condition of the photovoltaic panel, and lacks analysis of specific factors that affect the output working condition of the photovoltaic panel. This leads to the need for professionals to judge which factors cause the output abnormality of the photovoltaic panel based on their own experience when they monitor that the IV curve of a photovoltaic panel is abnormal.

[0003] In order to reduce the workload of professionals, the Chinese patent application document with publication number CN209881732U designs an outdoor split photovoltaic module IV tester. The instrument is equipped with an IV measurement unit and a meteorological information measurement unit for measuring the real-time meteorological information (mainly temperature information and wind speed and wind force information) of the target photovoltaic panel in the area. By providing real-time meteorological information to professionals, it assists professionals in determining the specific reasons for the abnormal IV curve of the target photovoltaic panel. Although this method can reduce the workload of professionals to a certain extent, real-time meteorological changes are not necessarily the main reason for the abnormal output of the IV curve. In the actual application environment, the current output of photovoltaics is mainly affected by the two parameters of light intensity and radiation area, and the external factors affecting these two parameters include both geographical factors and meteorological factors and time factors. Therefore, the above technology is used alone to evaluate the working conditions of photovoltaic panels, and the accuracy of the evaluation is low, and it is difficult to effectively judge the actual faults of photovoltaic panels. Summary of the invention

[0004] In order to solve the above-mentioned technical problem of low accuracy in evaluating the working condition of photovoltaic panels, the present invention provides solutions in the following aspects.

[0005] In a first aspect, the present invention provides a method for monitoring power generation of a photovoltaic panel, comprising: Obtain the output current, light receiving area, tilt angle, latitude and time of the target photovoltaic panel; The light receiving area, tilt angle, latitude and time are placed into the expected current calculation model to calculate the expected current; wherein the expected current calculation model is:

[0006] In the formula, is a sine function, is the cosine function, is the solar altitude angle, is the latitude, For time-based t The calculated solar declination angle is For time-based t The calculated hour angle is For time t The tilted radiation, is the direct solar radiation, is the tilt angle, For time t The expected current, is the photoelectric conversion coefficient of the target photovoltaic panel, is the light receiving area; The operating condition of the target photovoltaic panel is evaluated based on the deviation of the output current from the expected current.

[0007] Beneficial effects: When evaluating the working condition of photovoltaic panels, the method of the present invention incorporates the inclination angle and latitude represented by geographical factors, and also incorporates the time factor, and places these factors into the expected current calculation model to calculate the expected current, and then compares the expected current with the output current, and evaluates the working condition of the target photovoltaic panel based on the deviation of the two currents. Compared with the prior art, the method of the present invention can effectively model and associate the geographical and temporal factors that affect the light intensity, achieve specific quantification, and calculate a more accurate expected current to assist professionals in evaluating the output current, reduce the workload of professionals, and overcome the problem of low accuracy in the evaluation of photovoltaic panel working conditions in the prior art.

[0008] Preferably, the calculation formula of the solar declination angle is:

[0009] In the formula, To correct the parameters, N is the serial number, the time t Including the first N sky.

[0010] Beneficial effect: By obtaining the first NThe above formula can be used to calculate the solar declination angle more quickly. Under normal circumstances, a year is generally 365 days, but considering the specific situation of a leap year every four years, the date deviation caused by the leap year can be corrected by setting correction parameters, thereby improving the accuracy of the expected current calculation model.

[0011] Preferably, based on time t The calculated hour angle is:

[0012] in, For time-based t The calculated hour angle is ST represents the solar time of the time zone to which the target photovoltaic panel belongs, and time t includes the solar time of the time zone to which the target photovoltaic panel belongs.

[0013] Beneficial effect: The earth rotates about 15° per hour. In the 24-hour system, 12 represents noon, when the sun is at its highest altitude and the hour angle is 0, and the cosine value is the largest. Correspondingly, as the time of day changes, the sun's altitude will also change. Using the above formula to describe the change in the hour angle of sunlight can simulate objective facts to the greatest extent and improve the accuracy of the expected current calculation model.

[0014] Preferably, the operating condition of the target photovoltaic panel is evaluated according to the output current and the expected current, specifically: Give expected current Setting the deviation value , get the evaluation deviation value ; If the output current exceeds the upper limit of the evaluation deviation value within the preset period of time, , and determine that the target photovoltaic panel is in a short-circuit condition.

[0015] Beneficial effect: When the output current exceeds the upper limit of the evaluation deviation of the expected current, the target photovoltaic panel is determined to be in a short-circuit condition, so as to assist professionals to quickly find the photovoltaic panel in the short-circuit condition.

[0016] Preferably, within a preset period of time, if the output current is lower than the lower limit of the evaluation deviation value , the method of the present invention further comprises: Determine whether the output current is 0. If so, determine that the target photovoltaic panel is in an open circuit condition. If not, perform the following steps: Monitor the voltage and ambient temperature of the target photovoltaic panel; If the voltage is lower than the rated voltage and the ambient temperature is higher than the upper temperature limit, the target photovoltaic panel is judged to be in a high temperature condition; If the ambient temperature is lower than the lower temperature limit, the target photovoltaic panel is determined to be in a weak light condition.

[0017] Beneficial effect: For the case where the output current is lower than the lower limit of the evaluation deviation value, the method of the present invention considers the distinction between open circuit conditions, high temperature conditions and weak light conditions and optimizes the logical judgment algorithm, which can improve the efficiency of photovoltaic panel condition diagnosis.

[0018] Preferably, after monitoring the voltage of the target photovoltaic panel, the method of the present invention further comprises: A touch screen display module is used to display the IV characteristic curve of the target photovoltaic panel.

[0019] Preferably, after evaluating the operating condition of the target photovoltaic panel according to the output current and the expected current, the method of the present invention further comprises: Determine whether the target photovoltaic panel is in normal power generation condition. If not, issue a corresponding abnormal condition alarm.

[0020] Preferably, before obtaining the output current, light receiving area, tilt angle, latitude and time of the target photovoltaic panel, the method of the present invention further comprises: Detecting whether the insulation resistance of the target photovoltaic panel is within a predetermined resistance range; If not, a corresponding insulation resistance abnormality alarm is issued according to the insulation resistance value.

[0021] Beneficial effect: Before obtaining various data of the photovoltaic panel, first check whether the resistance value of the insulation resistor is within the normal range. If not, it means that the insulation performance of the insulation resistor may be defective, and a corresponding abnormal alarm is issued, which is conducive to professional personnel to maintain or replace the insulation resistor, thereby avoiding safety hazards.

[0022] Preferably, issuing a corresponding insulation resistance abnormality alarm according to the resistance value is specifically: If the insulation resistance value is higher than the upper limit of the resistance range, a residual charge alarm is issued; If the insulation resistance is lower than the lower limit of the resistance range, a short circuit leakage alarm will be issued.

[0023] In a second aspect, the present invention further provides a power generation monitoring system for photovoltaic panels, comprising a processor and a memory, wherein the memory stores computer program instructions for a power generation monitoring method for photovoltaic panels, and when the computer program instructions are executed by the processor, the power generation monitoring method for photovoltaic panels as described in the first aspect is implemented.

[0024] The beneficial effects of the present invention are: (1) Compared with the prior art, the method of the present invention can effectively model and associate the geographical and temporal factors that affect light intensity, realize specific automatic quantification, reduce the workload of professionals, and overcome the problem of low accuracy in the prior art in assessing the working conditions of photovoltaic panels.

[0025] (2) Compared with the prior art, the method of the present invention optimizes the logical judgment algorithm by distinguishing between open circuit conditions, high temperature conditions and weak light conditions when the output current is lower than the lower limit of the evaluation deviation value, which can improve the efficiency of photovoltaic panel condition diagnosis.

[0026] (3) Compared with the prior art, the method of the present invention first detects whether the resistance value of the insulation resistor is within the normal range before acquiring various data of the photovoltaic panel. If not, it indicates that the insulation performance of the insulation resistor may be defective, and a corresponding abnormal alarm is issued, which is conducive to professional personnel to maintain or replace the insulation resistor, thereby avoiding safety hazards. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a flow chart schematically illustrating a method for monitoring power generation of a photovoltaic panel according to a first embodiment of the present invention; Figure 2 is a flowchart schematically showing steps S31 to S36 of a method for monitoring power generation of a photovoltaic panel according to a second embodiment of the present invention; Figure 3 FIG. 1 is a schematic diagram schematically showing the structure of a photovoltaic panel power generation monitoring device according to Embodiment 3 of the present invention.

[0028] Figure 4 FIG. 1 is a schematic diagram schematically showing the connection of a photovoltaic panel power generation monitoring system according to a fourth embodiment of the present invention. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without making any creative work shall fall within the scope of protection of the present invention.

[0030] This embodiment discloses a method and system for monitoring power generation of photovoltaic panels, which are used to solve the problem of low accuracy in evaluating the working conditions of photovoltaic panels in the prior art.

[0031] Embodiment 1 like Figure 1 As shown, this embodiment discloses a method for monitoring power generation of a photovoltaic panel, comprising: S10: Obtain the output current, light receiving area, tilt angle, latitude and time of the target photovoltaic panel.

[0032] S20: The light receiving area, the tilt angle, the latitude and the time are placed into the expected current calculation model to calculate the expected current.

[0033] S30: Evaluate the operating condition of the target photovoltaic panel according to the deviation between the output current and the expected current.

[0034] Through the above schemes S10-S30, the method of the present invention can effectively associate the geographical and temporal factors that affect the light intensity, realize specific automatic quantification, and make it possible to obtain the expected current. After obtaining the expected current, the output current and the expected current are compared, and the specific operating conditions of the target photovoltaic panel are evaluated according to the degree of deviation of the two currents. Compared with the existing technology, this evaluation method is more accurate and efficient.

[0035] In this embodiment, the output current is recorded as , the light receiving area is denoted as S, and the latitude is denoted as The tilt angle refers to the tilt angle of the photovoltaic panel relative to the ground, recorded as , including the first N Day and solar time ST The above output current can be obtained by using the IV curve measurement circuit and analog-to-digital conversion module in the IV curve test device. The light-receiving area refers to the silicon wafer area of ​​the light-receiving surface of the target photovoltaic panel, and this area can generally be obtained according to the model of the photovoltaic panel. The tilt angle is obtained by using a gyroscope or an angle sensor. The latitude and time data can be obtained by using a GPS device.

[0036] It should be noted that based on the above latitude data, it can be known that the location of the photovoltaic panel is in the southern hemisphere or the northern hemisphere. If the target photovoltaic panel is located in the northern hemisphere, its azimuth can be adjusted to the south direction, and if it is located in the southern hemisphere, its azimuth can be adjusted to the north direction. This azimuth setting method can make the target photovoltaic panel receive the maximum radiation in one day.

[0037] In combination with the above explanations, the expected current calculation model in the above S20 can be:

[0038] In the formula, is a sine function, is the cosine function, is the solar altitude angle, is the latitude, For time-based t The calculated solar declination angle is For time-based t The calculated hour angle is For time t The tilted radiation, is the direct solar radiation, is the tilt angle, For time t The expected current, is the photoelectric conversion coefficient of the target photovoltaic panel, is the light receiving area.

[0039] It should be noted that in this embodiment, the photoelectric conversion coefficient is the energy conversion coefficient of the photovoltaic panel. This coefficient is related to the material and model of the photovoltaic panel and can be obtained by looking up the table (photovoltaic panel manual query). The above model is applicable to temperatures of 20°C-50°C, humidity of 45%-85%, and sunny weather. In other application environments, the above model can introduce temperature correction parameters or humidity correction parameters for optimization.

[0040] Through the above-mentioned expected current calculation model, an effective functional relationship between light intensity, geographical factors (latitude, tilt angle) and time factors is realized, and the specific quantification of tilt radiation is achieved, thereby obtaining a more accurate predicted current.

[0041] Furthermore, the calculation formula of the solar declination angle is:

[0042] in, To correct the parameters.

[0043] It should be explained that in the absence of accurate astronomical data, the above formula can be used to quickly calculate the solar declination angle. Under normal circumstances, a year is generally 365 days, but considering the leap year every four years, the correction parameters can be set to correct the date deviation caused by the leap year, thereby improving the accuracy of the expected current calculation model.

[0044] Preferably, the above The value range is 0-15.

[0045] Furthermore, the calculation formula for the above hour angle is:

[0046] The above formula calculates the specific hour angle according to the rotation of the earth and the change of time zone. Specifically, in the 24-hour system, 12 o'clock is exactly the noon time when the sun is at its highest altitude, and its hour angle corresponds to 0, which symbolizes the geographical time zone corresponding to the direct sunlight on the target photovoltaic panel. As the time changes in a day, the hour angle of the sun's altitude changes from low to high and then to low from morning to evening, and the above formula objectively describes this phenomenon. The hour angle calculated based on the above formula is more accurate, which can improve the accuracy of the expected current calculation model.

[0047] Preferably, the solar time ST is the solar time corrected according to the time zone where the target photovoltaic panel is located.

[0048] Embodiment 2 This embodiment discloses a method for monitoring power generation of a photovoltaic panel. In order to pre-diagnose whether the photovoltaic panel has potential safety hazards, before S10 described in the first embodiment, the method of the present invention further includes: S100: Detect whether the insulation resistance of the target photovoltaic panel is within a predetermined resistance range.

[0049] S101: If yes, an executable notification is issued on the touch screen of the IV curve test device; if no, a corresponding insulation resistance abnormality alarm is issued according to the insulation resistance value.

[0050] More specifically, the above S101 is: If the insulation resistance value is higher than the upper limit of the resistance range, a residual charge alarm is issued.

[0051] If the insulation resistance is lower than the lower limit of the resistance range, a short circuit leakage alarm will be issued.

[0052] The above technical solutions S100-S101 are helpful for professionals to know whether the insulation resistance is abnormal in time, and maintain or replace the insulation resistance, so as to avoid the situation where the output current in S10 is inaccurate due to the abnormal insulation resistance.

[0053] In this embodiment, in order to improve the accuracy of the expected current calculation model, this embodiment takes into account factors such as weather, temperature and humidity. The above-mentioned expected current calculation model can be modified as follows:

[0054] in, represents the humidity coefficient, The value ranges from 0.00 to 1.00, which is positively correlated with the local humidity of the photovoltaic panel. It represents the temperature coefficient, and its value range is 0°-90°, which can be converted proportionally to the ambient temperature of the photovoltaic panel in the range of -40℃-85℃. Indicates the weather coefficient. When the weather is sunny, When the weather is cloudy and rainy, The expression is: =

[0055] like Figure 2 As shown, in order to improve the evaluation performance of the method of the present invention, S30 of this embodiment is specifically as follows: S31: Provide expected current Setting the deviation value , get the evaluation deviation value .

[0056] In this embodiment, after the expected current is set to a deviation value, the upper limit of the evaluation deviation value is +ΔI , and the lower limit of the evaluation deviation value is -ΔI .

[0057] S32: Within the preset period, if the output current exceeds the upper limit of the evaluation deviation value +ΔI , and determine that the target photovoltaic panel is in a short-circuit condition.

[0058] S33: Within the preset period, if the output current is lower than the lower limit of the evaluation deviation value - ΔI , determine whether the output current is 0, if so, determine that the target photovoltaic panel is in an open circuit condition, if not, execute steps S34-S36: S34: Monitor the voltage of the target photovoltaic panel and ambient temperature .

[0059] S35: If the voltage Below rated voltage And the ambient temperature Above the upper temperature limit , and determine that the target photovoltaic panel is in high temperature condition.

[0060] S36: If the ambient temperature Below the lower limit of temperature , and determine that the target photovoltaic panel is in a weak light condition.

[0061] Compared with the prior art, the method of the present invention can specifically evaluate the short circuit, open circuit, high temperature and weak light conditions of the photovoltaic panel, which can effectively improve the efficiency of photovoltaic panel working condition diagnosis and assist professionals to quickly perform fault assessment on abnormal photovoltaic panels.

[0062] Furthermore, after the voltage is monitored in the above S34, the method of the present invention uses a touch screen display module to display the IV characteristic curve of the target photovoltaic panel, so that the IV characteristic curve is visualized, thereby facilitating fault analysis by professionals.

[0063] Furthermore, after S36, the method of the present invention further includes: Determine whether the target photovoltaic panel is in normal power generation condition, if not, issue a corresponding abnormal condition alarm. Specifically, when the above short circuit, open circuit, high temperature and weak light conditions occur, the method of the present invention will issue a corresponding type of text alarm to the touch screen display module.

[0064] Embodiment 3 like Figure 3As shown, this embodiment discloses a photovoltaic panel power generation monitoring device, which is used to implement the photovoltaic panel power generation monitoring method recorded in embodiment one or two. The device of the present invention includes a data acquisition module, an expected current calculation module and a working condition evaluation module.

[0065] Among them, the data acquisition module is used to obtain the output current, light receiving area, tilt angle, latitude and time of the target photovoltaic panel. More specifically, the data acquisition module is composed of an IV curve measurement circuit, an insulation resistance measurement circuit, a GPS device, a sensor slave, an analog-to-digital conversion module and a LoRa module. The expected current calculation module is used to place the light receiving area, tilt angle, latitude and time into the expected current calculation model to calculate the expected current. The expected current calculation module is built into the main control CPU. The operating condition evaluation module is also built into the main control CPU, and is used to evaluate the operating condition of the target photovoltaic panel based on the output current and the expected current.

[0066] Preferably, the master CPU can be RK3568, which is a low-cost microprocessor that can process data efficiently. The sensor slave is provided with an irradiance sensor (for real-time monitoring of direct solar radiation). ), temperature sensor and angle sensor (gyroscope), the sensor slave uses the above sensors to wirelessly transmit the monitoring data to the main control CPU through the LoRa module. The probes of the IV curve measurement circuit and the insulation resistance measurement circuit are directly connected to the target photovoltaic panel. The analog signals collected by these two circuits are converted into digital signals through the analog-to-digital conversion module and transmitted to the main control CPU for processing.

[0067] Furthermore, the storage unit of the main control CPU uses an SD card, which communicates with the outside world through an Ethernet module. The touch screen display module can display IV characteristic curves, temperature, and direct solar radiation. And the insulation resistance value, so that professionals can observe the performance of photovoltaic panels in real time.

[0068] Embodiment 4 like Figure 4 As shown, this embodiment discloses a power generation monitoring system for a photovoltaic panel, including a processor and a memory, wherein the memory stores computer program instructions for a power generation monitoring method for a photovoltaic panel, and when the computer program instructions are executed by the processor, the power generation monitoring method for a photovoltaic panel as described in Embodiment 1 or 2 is implemented.

[0069] Although this specification has shown and described multiple embodiments of the present invention, it is obvious to those skilled in the art that such embodiments are provided by way of example only. It should be understood that in the process of practicing the present invention, various alternatives to the embodiments of the present invention described herein may be adopted.

Claims

1. A method for monitoring power generation of a photovoltaic panel, characterized in that: include: Obtain the output current, light receiving area, tilt angle, latitude and time of the target photovoltaic panel; The light receiving area, the tilt angle, the latitude and the time are placed into an expected current calculation model to calculate the expected current; wherein the expected current calculation model is: In the formula, is a sine function, is the cosine function, is the solar altitude angle, is the latitude, Based on the time t The calculated solar declination angle is Based on the time t The calculated hour angle is For time t The tilted radiation, is the direct solar radiation, is the tilt angle, For time t The expected current, is the photoelectric conversion coefficient of the target photovoltaic panel, is the light receiving area; The operating condition of the target photovoltaic panel is evaluated according to the deviation between the output current and the expected current.

2. The method for monitoring power generation of photovoltaic panels according to claim 1, characterized in that: The calculation formula for the solar declination angle is: in, To correct the parameters, N is the serial number, the time t Including the first N sky.

3. The method for monitoring power generation of photovoltaic panels according to claim 1, characterized in that: Based on the time t The calculated hour angle is: in, Based on the time t The calculated hour angle is ST Indicates the solar time in the time zone where the target photovoltaic panel belongs. t Includes solar time in the time zone where the target PV panels are located.

4. The method for monitoring power generation of photovoltaic panels according to claim 1, characterized in that: According to the output current and the expected current, the operating condition of the target photovoltaic panel is evaluated, specifically: Give the expected current Setting the deviation value , get the evaluation deviation value ; Within a preset period of time, if the output current exceeds the upper limit of the evaluation deviation value , it is determined that the target photovoltaic panel is in a short-circuit condition.

5. The method for monitoring power generation of photovoltaic panels according to claim 4, characterized in that: Within a preset period of time, if the output current is lower than the lower limit of the evaluation deviation value , the power generation monitoring method further includes: Determine whether the output current is 0. If so, determine that the target photovoltaic panel is in an open circuit condition. If not, perform the following steps: Monitoring the voltage and ambient temperature of the target photovoltaic panel; If the voltage is lower than the rated voltage and the ambient temperature is higher than the upper temperature limit, the target photovoltaic panel is determined to be in a high-temperature operating condition; if the ambient temperature is lower than the lower temperature limit, the target photovoltaic panel is determined to be in a weak-light operating condition.

6. The method for monitoring power generation of photovoltaic panels according to claim 5, characterized in that: After monitoring the voltage of the target photovoltaic panel, the power generation monitoring method further includes: A touch screen display module is used to display the IV characteristic curve of the target photovoltaic panel.

7. The method for monitoring power generation of photovoltaic panels according to claim 1, characterized in that: Before obtaining the output current, light receiving area, tilt angle, latitude and time of the target photovoltaic panel, the power generation monitoring method further includes: Detecting whether the insulation resistance of the target photovoltaic panel is within a predetermined resistance range; If not, a corresponding insulation resistance abnormality alarm is issued according to the insulation resistance value.

8. The method for monitoring power generation of photovoltaic panels according to claim 7, characterized in that: The corresponding insulation resistance abnormality alarm is issued according to the insulation resistance value, specifically: If the insulation resistance is higher than the upper limit of the resistance range, a residual charge alarm is issued; If the insulation resistance is lower than the lower limit of the resistance range, a short circuit and leakage alarm is issued.

9. The method for monitoring power generation of photovoltaic panels according to claim 1, characterized in that: After evaluating the operating condition of the target photovoltaic panel according to the output current and the expected current, the power generation monitoring method further includes: Determine whether the target photovoltaic panel is in normal power generation condition, and if not, issue a corresponding abnormal condition alarm.

10. A power generation monitoring system for photovoltaic panels, characterized in that: The method comprises a processor and a memory, wherein the memory stores computer program instructions for a method for monitoring power generation of a photovoltaic panel, and when the computer program instructions are executed by the processor, the method for monitoring power generation of a photovoltaic panel as claimed in any one of claims 1 to 9 is implemented.

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