System for diagnosing insulation resistance of photovoltaic power generation facility

Abstract

The present invention relates to a system for diagnosing insulation resistance of a photovoltaic power generation facility and, more specifically, to a system for diagnosing insulation resistance of a photovoltaic power generation facility, in which while insulation resistance is being measured by applying a voltage to a string for a predetermined time, a kick index indicating a degree of change for each unit time can be calculated so as to diagnose an abnormality in the insulation resistance. Thus, deterioration of the insulation resistance can be identified regardless of various environments, thereby enabling the prevention of accidents in advance.

Description

Solar power plant insulation resistance diagnosis system

[0001] The present invention relates to a solar power generation facility insulation resistance diagnosis system, and more specifically, to a solar power generation facility insulation resistance diagnosis system that measures insulation resistance by applying voltage to a string for a certain period of time and calculates a kick index indicating the degree of change per unit time to diagnose an abnormality in insulation resistance, thereby enabling the deterioration of insulation resistance to be identified regardless of various environments, thereby enabling the prevention of accidents in advance.

[0002] Solar power, a renewable energy source, has seen a surge in demand recently due to its numerous advantages, and technologies to improve power generation efficiency have also been advancing rapidly. In particular, solar power generation systems are being installed in various forms, including rooftops, floating structures, and even building-integrated photovoltaic (BIPV) systems that are integrated into buildings.

[0003] Solar power generation devices must be constantly exposed to the sun to achieve high efficiency, and they pose a high risk of fire due to the heat generated by power generation, and in particular, the decrease in insulation resistance is identified as a major cause of fire.

[0004] Therefore, it is necessary to regularly measure and check the insulation resistance of solar power generation equipment. To this end, as described in the patent document below, a technician periodically visits the site to measure the insulation resistance and check whether it exceeds the standard value.

[0005] However, in these cases, not only is there the inconvenience of having to have a technician visit periodically, but insulation resistance is affected by the environment such as humidity, so an accurate diagnosis of the insulation resistance status cannot be made simply by comparing it with a reference value.

[0006] In addition, if the insulation resistance falls below the standard value, it is already exposed to the risk of fire, and there is a problem that the insulation resistance gradually deteriorates, making it impossible to prevent a fire from occurring in advance.

[0007] (Patent Document) Patent Publication No. 10-1529476 (registered on June 11, 2015) "Insulation Resistance Monitoring System for Solar Module Strings"

[0008] The present invention has been devised to solve the above problems.

[0009] The purpose of the present invention is to provide a solar power generation facility insulation resistance diagnosis system that measures insulation resistance by applying voltage to a string for a certain period of time and calculates a kick index that indicates the degree of change per unit time to diagnose an abnormality in insulation resistance, thereby enabling the deterioration of insulation resistance to be identified regardless of various environments, thereby preventing accidents in advance.

[0010] The purpose of the present invention is to provide a solar power generation facility insulation resistance diagnosis system that enables more accurate identification of the insulation resistance deterioration status by calculating a kick index while gradually changing the voltage applied over a certain period of time.

[0011] The purpose of the present invention is to provide a solar power generation facility insulation resistance diagnosis system that enables efficient diagnosis work by diagnosing an imbalance between solar modules in a string and the cause of the imbalance, and by diagnosing the insulation resistance state when an imbalance due to a decrease in insulation resistance is suspected.

[0012] The purpose of the present invention is to provide a solar power generation facility insulation resistance diagnosis system that enables accurate diagnosis of an unbalanced state by diagnosing an unbalanced state of solar module output according to the degree of unbalance in voltage between modules in a string and the degree of voltage fluctuation.

[0013] The purpose of the present invention is to provide a solar power plant insulation resistance diagnosis system that can detect a voltage imbalance condition in a simple manner without measuring the voltage of all solar modules by diagnosing the voltage imbalance condition by comparing the voltage of a specific module multiplied by the number of modules with the voltage of the entire string.

[0014] The purpose of the present invention is to provide a solar power generation facility insulation resistance diagnosis system that calculates an imbalance index indicating the degree of output imbalance between modules using the degree of voltage imbalance and the degree of voltage fluctuation within a string, and detects the cause of the imbalance according to the imbalance index, thereby enabling a quick and accurate response to the imbalance.

[0015] In order to achieve the above-mentioned purpose, the present invention is implemented by an embodiment having the following configuration.

[0016] According to one embodiment of the present invention, a solar power generation facility insulation resistance diagnosis system according to the present invention includes an insulation resistance diagnosis unit that precisely diagnoses whether the insulation resistance of a string has decreased, and the insulation resistance diagnosis unit is characterized by including a voltage application module that applies voltage to the string for a certain period of time, an insulation resistance measurement module that measures insulation resistance at unit time intervals according to the voltage application, a kick index calculation module that calculates a kick index indicating a degree of change in insulation resistance per unit time for a certain period of time, and an abnormality detection module that determines that there is an insulation resistance abnormality when the calculated kick index exceeds a set reference value.

[0017] According to another embodiment of the present invention, in the solar power generation facility insulation resistance diagnosis system according to the present invention, the insulation resistance diagnosis unit is characterized in that it includes a diagnosis time setting module that sets a diagnosis time of the insulation resistance status.

[0018] According to another embodiment of the present invention, in the solar power generation facility insulation resistance diagnosis system according to the present invention, the kick index calculation module is characterized in that it calculates the time kick index by the following mathematical expression 1.

[0019] (Equation 1)

[0020]

[0021] According to another embodiment of the present invention, a solar power generation facility insulation resistance diagnosis system according to the present invention is characterized by including a voltage adjustment module that allows measurement of insulation resistance while changing voltage in steps.

[0022] According to another embodiment of the present invention, in the solar power generation facility insulation resistance diagnosis system according to the present invention, the kick index calculation module is characterized in that it calculates the voltage kick index by the following mathematical expression 2.

[0023] (Equation 2)

[0024]

[0025] According to another embodiment of the present invention, a solar power generation facility insulation resistance diagnosis system according to the present invention includes a module imbalance diagnosis unit that diagnoses imbalance between solar modules in a string, and the insulation resistance diagnosis unit is characterized in that it performs a diagnosis of insulation resistance when an imbalance due to a decrease in insulation resistance is diagnosed by the module imbalance diagnosis unit.

[0026] According to another embodiment of the present invention, in the solar power generation facility insulation resistance diagnosis system according to the present invention, the module imbalance diagnosis unit is characterized by including a voltage imbalance calculation unit that calculates the degree of imbalance in voltage between modules constituting a string, a fluctuation abnormality calculation unit that calculates the degree of abnormality according to voltage and current fluctuations of the string, and an imbalance detection unit that detects imbalance between modules of the string according to the degree of voltage imbalance and the degree of fluctuation abnormality.

[0027] According to another embodiment of the present invention, in the solar power generation facility insulation resistance diagnosis system according to the present invention, the voltage imbalance calculation unit is characterized by including a string voltage measurement module that measures the voltage of power output from a string, a module voltage measurement module that measures the voltage of a specific module in the string, and a voltage imbalance coefficient calculation module that calculates a voltage imbalance coefficient indicating the degree of voltage imbalance between modules by subtracting a value obtained by multiplying the number of solar modules included in the string by the voltage of the specific module from the string voltage.

[0028] According to another embodiment of the present invention, in the solar power generation facility insulation resistance diagnosis system according to the present invention, the voltage imbalance calculation unit is characterized by including a voltage imbalance diagnosis module that compares the voltage imbalance coefficient calculated by the imbalance coefficient calculation module with a reference value, and if the voltage imbalance coefficient exceeds the reference value, diagnoses the voltage imbalance between modules and executes a fluctuation abnormality calculation unit.

[0029] According to another embodiment of the present invention, in the solar power generation facility insulation resistance diagnosis system according to the present invention, the fluctuation abnormality calculation unit is characterized by including a voltage measurement module that measures a voltage output from a string for a certain period of time, a current measurement module that measures a current output from a string for a certain period of time, and a power fluctuation coefficient calculation module that calculates a value of a ratio of voltage change to current change for a ratio of voltage to current per unit time for a certain period of time and calculates a power fluctuation coefficient representing the degree of voltage and current fluctuation by an average value thereof.

[0030] According to another embodiment of the present invention, in the solar power generation facility insulation resistance diagnosis system according to the present invention, the fluctuation abnormality calculation unit is characterized in that it includes a coefficient adjustment module that increases the scale while changing the standard for the normal state of the power fluctuation coefficient to 0.

[0031] According to another embodiment of the present invention, in the solar power generation facility insulation resistance diagnosis system according to the present invention, the coefficient adjustment module is characterized in that it adjusts the power variation coefficient by mathematical expression 4 to calculate the final power variation coefficient.

[0032] (Equation 4)

[0033] Pf = (1-Pd)*10

[0034] (Here, Pf is the adjusted power variation coefficient, and Pd is the initial power variation coefficient)

[0035] According to another embodiment of the present invention, in the solar power generation facility insulation resistance diagnosis system according to the present invention, the imbalance detection unit is characterized by including a voltage imbalance coefficient loading module for loading a voltage imbalance coefficient, a power variation coefficient loading module for loading a power variation coefficient, an imbalance index calculation module for calculating an imbalance index indicating the degree of output imbalance between modules by multiplying the voltage imbalance coefficient and the power variation coefficient, and an abnormality information diagnosis module for diagnosing an abnormal state due to output imbalance between modules of a string according to the calculated imbalance index.

[0036] According to another embodiment of the present invention, in the solar power generation facility insulation resistance diagnosis system according to the present invention, the abnormal information diagnosis module is characterized in that when the unbalance index is positive, it diagnoses module breakage, shading, or contamination, and when the unbalance index is negative, it diagnoses PID, cell cracking, or insulation resistance reduction.

[0037] The present invention can obtain the following effects through the combination and use of the configuration described above and the following examples.

[0038] The present invention measures insulation resistance by applying voltage to a string for a certain period of time, calculates a kick index indicating the degree of change per unit time, and diagnoses an abnormality in insulation resistance, thereby enabling the deterioration of insulation resistance to be identified regardless of various environments, thereby enabling the prevention of accidents in advance.

[0039] The present invention has the effect of enabling more accurate identification of the insulation resistance deterioration state by calculating the kick index while gradually changing the voltage applied over a certain period of time.

[0040] The present invention has the effect of enabling efficient diagnosis work by diagnosing an imbalance state between solar modules in a string and the cause of the imbalance state, and by diagnosing the insulation resistance state when an imbalance state due to a decrease in insulation resistance is suspected.

[0041] The present invention has the effect of enabling accurate diagnosis of an imbalance state by diagnosing an imbalance state in the output of a solar module according to the degree of imbalance in voltage between modules in a string and the degree of voltage fluctuation.

[0042] The present invention has the effect of enabling the detection of a voltage imbalance in a simple manner without having to measure the voltage of all solar modules, by diagnosing a voltage imbalance by comparing the voltage of a specific module multiplied by the number of modules with the voltage of the entire string.

[0043] The present invention has the effect of enabling a method of calculating an imbalance index indicating a degree of output imbalance between modules by using the degree of voltage imbalance and the degree of voltage fluctuation within a string, and enabling the cause of an imbalance state to be detected based on the imbalance index, thereby enabling a quick and accurate response to an imbalance state.

[0044] Figure 1 is a block diagram showing the configuration of a solar power generation facility insulation resistance diagnosis system according to one embodiment of the present invention.

[0045] Figure 2 is a block diagram showing the configuration of the insulation resistance diagnosis unit.

[0046] Figure 3 is a graph showing an example of insulation resistance measurement.

[0047] Figure 4 is a block diagram showing the configuration of the module imbalance diagnosis unit.

[0048] Figure 5 is a reference diagram showing an example of voltage measurement by a voltage imbalance calculation unit.

[0049] Figure 6 is a graph showing an example of voltage change according to string status.

[0050] Figure 7 is a reference diagram showing the operating point on the IV curve according to the imbalance index.

[0051] Figure 8 is a block diagram showing the configuration of the power generation prediction unit.

[0052] Figure 9 is a block diagram showing the configuration of the fault diagnosis unit.

[0053] Figure 10 is a reference diagram showing an IV graph used by the fault diagnosis unit.

[0054] *Explanation of symbols used in drawings

[0055] 1: Insulation resistance diagnostic section 2: Module imbalance diagnostic section

[0056] 21: Voltage imbalance calculation unit 22: Fluctuation abnormality calculation unit

[0057] 23: Imbalance detection unit 3: Power generation prediction unit

[0058] 4: Power generation measurement section 5: Fault diagnosis section

[0059] Hereinafter, preferred embodiments of a solar power plant insulation resistance diagnosis system according to the present invention will be described in detail with reference to the attached drawings. In the following description of the present invention, if it is determined that a detailed description of a known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Throughout the specification, when a part is said to "include" a certain component, this does not mean that other components are excluded, but rather that other components may be further included, unless specifically stated otherwise, and also, terms such as "... part", "... module" described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware, software, or a combination of hardware and software.

[0060] A solar power generation facility insulation resistance diagnosis system according to one embodiment of the present invention will be described with reference to FIGS. 1 to 10. The solar power generation facility insulation resistance diagnosis system includes an insulation resistance diagnosis unit (1) that precisely diagnoses whether insulation resistance has decreased, a module imbalance diagnosis unit (2) that diagnoses imbalance between modules in a string, a power generation prediction unit (3) that predicts the power generation amount for each string of a solar power generation device, a power generation measurement unit (4) that measures the current power generation amount of a string in real time, and a fault diagnosis unit (5) that diagnoses the type of fault in a string by using an area on an IV coordinate plane according to the predicted power generation amount and the measured power generation amount.

[0061] Conventional insulation resistance diagnosis has been limited to comparing measured insulation resistance values ​​with reference values, which has led to the problem of not being able to diagnose localized insulation resistance degradation and deterioration in various environments. Therefore, the insulation resistance diagnosis system monitors changes in insulation resistance while applying voltage for a certain period of time and diagnoses insulation resistance degradation based on the changes, thereby enabling accurate diagnosis of insulation resistance degradation in various environments and even under localized defects.

[0062] In addition, the insulation resistance diagnosis system can diagnose an unbalanced condition between solar modules in a string, and when an unbalanced condition is diagnosed and a decrease in insulation resistance is suspected, the insulation resistance can be diagnosed to enable efficient operation of the system.

[0063] In addition, the insulation resistance diagnosis system can diagnose a decrease in power generation for a string, and in addition to comparing the existing predicted power generation with the current power generation, it can identify the type of failure by using the area on the IV coordinate plane, thereby enabling a more rapid response to the decrease in power generation, and when the cause of the decrease in power generation is suspected to be insulation resistance, a precise diagnosis of the insulation resistance can be performed by the insulation resistance diagnosis unit (1).

[0064] The above insulation resistance diagnosis system can enable remote monitoring of multiple solar power generation facilities, and can enable monitoring by remotely receiving voltage, current, insulation resistance, etc. measured through connections, etc., without requiring workers to go to the site.

[0065] The above insulation resistance diagnosis unit (1) is configured to diagnose a decrease in the insulation resistance of a string, and can preferably be run at night when the solar power generation facility is not in operation. In addition, as described above, it can be run when an imbalance between modules is diagnosed by the module imbalance diagnosis unit (2) or a decrease in power generation is diagnosed by the fault diagnosis unit (5), and the insulation resistance is suspected. The above insulation resistance diagnosis unit (1) can monitor the change in the insulation resistance while applying voltage for a certain period of time in order to accurately determine the state of insulation resistance decrease according to various environments, the state of deterioration due to local defects, etc., and when the range of change in the insulation resistance is large or a sudden change occurs, it can be determined that the insulation resistance is abnormal. To this end, the insulation resistance diagnosis unit (1) may include a diagnosis period setting module (11), a voltage application module (12), a voltage adjustment module (13), an insulation resistance measurement module (14), a kick index calculation module (15), and an abnormality detection module (16).

[0066] The above-mentioned diagnosis time setting module (11) is configured to set the time for measuring insulation resistance, and can be configured to perform the measurement at night when no power generation is performed. For example, the above-mentioned diagnosis time setting module (11) can be configured to set a specific time, or can be configured to automatically initiate measurement by monitoring the amount of power generation. In addition, the above-mentioned diagnosis time setting module (11) can be configured to operate at a set time only when a decrease in insulation resistance is suspected by the above-mentioned fault diagnosis unit (5) or module imbalance diagnosis unit (2), thereby enabling efficient measurement and diagnosis.

[0067] The above voltage application module (12) is configured to apply voltage to a string to measure insulation resistance, and can apply voltage for a certain period of time, for example, 10 minutes.

[0068] The voltage regulation module (13) is configured to regulate the voltage applied by the voltage application module (12), and can measure changes in insulation resistance in various voltage situations by increasing the voltage in steps. For example, the voltage regulation module (13) can increase the voltage in steps from 100 V to 500 V.

[0069] The above insulation resistance measurement module (14) is configured to measure insulation resistance for a certain period of time while voltage is applied. For example, when voltage is applied for 10 minutes, insulation resistance can be measured every second. In addition, when insulation resistance is measured while increasing voltage in stages by the voltage adjustment module (13), insulation resistance can be measured every time the voltage is increased.

[0070] The kick index calculation module (15) above is configured to calculate a kick index indicating the degree of change in insulation resistance. If the insulation resistance measured by the insulation resistance measurement module (14) in units of time or voltage does not change linearly but has a large change range or a rapid change as shown in FIG. 3, it can be determined that the insulation resistance has decreased. Accordingly, the kick index calculation module (15) can calculate the degree to which the insulation resistance changes on average as a kick index, and can calculate a time kick index regarding the degree of change per unit time when a constant voltage is applied for a certain period of time, and a voltage kick index regarding the degree of change each time the voltage is changed when the voltage is applied while being adjusted in steps for a certain period of time. At this time, the time kick index can be calculated by the following (Mathematical Expression 1), and the voltage kick index can be calculated by the following (Mathematical Expression 2).

[0071] (Equation 1)

[0072]

[0073] (Equation 2)

[0074]

[0075] The above abnormality detection module (16) is configured to detect an abnormal state due to a decrease in insulation resistance, and can be configured to determine that a state of danger has occurred due to a decrease in insulation resistance when the time kick index or voltage kick index calculated by the kick index calculation module (15) exceeds a set value.

[0076] The above module imbalance diagnosis unit (2) is configured to diagnose imbalance between solar modules in a string, and to diagnose imbalance in performance caused by failure, damage, aging, etc. The above module imbalance diagnosis unit (2) can be configured to diagnose in real time at regular intervals, or can be configured to be executed when a decrease in power generation is diagnosed by the above failure diagnosis unit (5). In particular, the above module imbalance diagnosis unit (2) comprehensively considers the degree of imbalance in voltage between solar modules and the degree of voltage fluctuation to diagnose the imbalance condition, thereby increasing the accuracy of the diagnosis. In other words, the module imbalance diagnosis unit (2) detects the degree to which the voltages between solar modules do not match, and in addition, considers the degree of voltage fluctuation in the diagnosis of the imbalance state. In the string inverter, the maximum power point tracking control (MPPT) is performed to find the maximum output point and fluctuate the voltage and current. In the normal state, the voltage and current fluctuate within a certain range, but when an imbalance occurs between solar modules, the fluctuation range of the voltage and current increases or decreases beyond a certain range. Therefore, by reflecting this and diagnosing the imbalance state, the accuracy of the diagnosis can be further increased. To this end, the module imbalance diagnosis unit (2) may include a voltage imbalance calculation unit (21), a fluctuation abnormality calculation unit (22), and an imbalance detection unit (23).

[0077] The voltage imbalance calculation unit (21) above is configured to calculate the degree of voltage imbalance between solar modules in a string, and in particular, uses the voltage output from the string and the voltage measured from a specific module in the string. Conventionally, in order to detect voltage imbalance between modules in a string, the voltage of each module had to be measured and compared, but in this case, there was a problem that installation and maintenance costs increased. Therefore, the voltage imbalance calculation unit (21) calculates the degree of voltage imbalance by comparing the voltage of the string and the voltage of a specific module multiplied by the number of modules, thereby simplifying installation and maintenance and reducing cost and time. In other words, if there is no imbalance between solar modules, the voltage of the string will be equal to the voltage of a specific module multiplied by the number of modules, and thus the degree of voltage imbalance can be calculated based on the difference. To this end, the voltage imbalance calculation unit (21) may include a string voltage measurement module (211), a module voltage measurement module (212), a voltage imbalance coefficient calculation module (213), and a voltage imbalance diagnosis module (214).

[0078] The above string voltage measurement module (211) is configured to measure the voltage output from the string, and can measure the voltage at the output terminal of the string as shown in FIG. 5.

[0079] The above module voltage measurement module (212) is configured to measure the voltage of a specific module within a string, and measures the voltage of only one of a number of solar modules included in the string. For example, it can measure the voltage of the module at the final stage.

[0080] The above voltage imbalance coefficient calculation module (213) is configured to calculate a voltage imbalance coefficient that indicates the degree of voltage imbalance of modules within a string, and can calculate the voltage imbalance coefficient by subtracting a value obtained by multiplying the voltage of a specific module by the number of modules from the string voltage. Accordingly, the greater the degree of voltage imbalance between modules within a string, the greater the voltage imbalance coefficient.

[0081] The above voltage imbalance diagnosis module (214) is configured to diagnose a voltage imbalance state of a string when the voltage imbalance coefficient exceeds a set reference value, and can be configured to execute a fluctuation abnormality calculation unit (22) when a voltage imbalance state is diagnosed.

[0082] The above fluctuation abnormality calculation unit (22) is configured to calculate the abnormality degree of the voltage fluctuation of the string, and reflects the voltage fluctuation degree in the calculation of the degree of imbalance by expressing it numerically. As described above, in the case of a normal state, as shown in FIG. 6, the string continues to fluctuate in a certain range of voltage as in ① and tracks the maximum power point. However, in the case where the voltage fluctuation range is too large or too small outside a certain range as in ② and ③, it is determined to be an abnormal state of fluctuation and the degree thereof is calculated. In addition, the fluctuation abnormality calculation unit (22) adjusts the scale and reference value to calculate the degree of imbalance by linking the abnormality degree of voltage fluctuation with the voltage imbalance coefficient. To this end, the fluctuation abnormality calculation unit (22) may include a voltage measurement module (221), a current measurement module (222), a power fluctuation coefficient calculation module (223), and a coefficient adjustment module (224).

[0083] The above voltage measurement module (221) is configured to measure the voltage output from the string, and calculates the degree of change per unit time by measuring for a certain period of time.

[0084] The above current measurement module (222) is configured to measure the current output from the string, and calculates the degree of change with the voltage by measuring it for a certain period of time, similar to voltage.

[0085] The above power variation coefficient calculation module (223) is configured to calculate the power variation coefficient that indicates the degree of voltage and current variation, and calculates the degree of voltage and current variation per unit time. For example, the above power variation coefficient calculation module (223) can calculate the power variation coefficient as the value obtained by dividing the change range ratio of voltage and current by the size ratio of voltage and current, as shown in the following (Mathematical Expression 3). If there is no imbalance between modules, the power variation coefficient will have a value close to 1, and if the voltage variation range is large, it will have a value less than 1, and if the voltage variation range is small, it will have a value greater than 1.

[0086] (Equation 3)

[0087]

[0088] (I, V = current, voltage / dI, dV = fluctuations in current, voltage)

[0089] At this time, a large voltage change range means that a specific module has deteriorated or the power generation has decreased due to negative radiation, contamination, etc., and it means a state in which the voltage is changed greatly as in ② of Fig. 6 in order to find the maximum power point by the MPPT algorithm of the inverter. In addition, a small voltage change range and a power variation coefficient greater than 1 means a state in which the power generation performance of the module has significantly decreased as in ③ of Fig. 6 in which the voltage variation amount is almost non-existent compared to the current variation amount. The power variation coefficient calculation module (223) may be configured to calculate the power variation coefficient per unit time, for example, 5 seconds or 10 seconds, and may be configured to determine the final power variation coefficient as the average value of the power variation coefficient per unit time for a certain period of time.

[0090] The above coefficient adjustment module (224) is configured to adjust the final power variation coefficient calculated by the power variation coefficient calculation module (223) to link it with the voltage imbalance coefficient, and can calculate the adjusted power variation coefficient by converting the standard of the normal state from 1 to 0 and increasing the scale, as shown below (Mathematical Formula 4).

[0091] (Equation 4)

[0092] Pf = (3-Pd)*10

[0093] (Here, Pf is the adjusted power variation coefficient, and Pd is the final power variation coefficient)

[0094] Therefore, in a normal state where there is no imbalance between modules, the adjusted power variation coefficient becomes 0, a power variation coefficient less than 1 is converted to a positive number, and a power variation coefficient greater than 1 is converted to a negative number.

[0095] The above-described imbalance detection unit (23) is configured to detect the imbalance state of modules within a string, and calculates the degree of imbalance between modules by reflecting the degree of voltage imbalance calculated by the voltage imbalance calculation unit (21) and the degree of voltage fluctuation abnormality calculated by the fluctuation abnormality calculation unit (22), and in particular, the cause of module imbalance can be diagnosed based on the calculated degree of imbalance. To this end, the above-described imbalance detection unit (23) may include a voltage imbalance coefficient loading module (231), a power fluctuation coefficient loading module (232), an imbalance index calculation module (233), and an abnormality information diagnosis module (234).

[0096] The above voltage imbalance coefficient loading module (231) is configured to load the voltage imbalance coefficient calculated by the voltage imbalance calculation unit (21), and loads the voltage imbalance coefficient calculated by the voltage imbalance coefficient calculation module (213).

[0097] The above power variation coefficient loading module (232) is configured to load the power variation coefficient calculated by the variation anomaly calculation unit (22), and loads the power variation coefficient adjusted by the coefficient adjustment module (224).

[0098] The above-mentioned imbalance index calculation module (233) is configured to calculate an imbalance index indicating the degree of imbalance between modules, and can calculate the imbalance index by multiplying a voltage imbalance coefficient and a power variation coefficient.

[0099] The above abnormal information diagnosis module (234) is configured to diagnose an imbalance state between modules according to an imbalance index, and can diagnose an imbalance state when the imbalance index exceeds a set value. Since the imbalance index is a value obtained by multiplying the degree of voltage imbalance and the degree of abnormal fluctuation, a larger absolute value indicates a more severe degree of imbalance, and since the power fluctuation coefficient is calculated as a positive or negative number depending on the power fluctuation state, a positive imbalance index indicates a state in which the voltage fluctuation is large, and a negative imbalance index indicates a state in which the voltage fluctuation is small and the current fluctuation is large. Therefore, as illustrated in FIG. 7, when the imbalance index is positive, it means that it is operating to the left (ⓐ) of the normal maximum power point, which indicates a state in which the series resistance is large, and damage, shade, or contamination of the module may be suspected. In addition, when the imbalance index is negative, it means that it is operating to the right (ⓑ) of the normal maximum power point, which indicates a state in which the parallel resistance is small, and leakage current, cell cracking, or reduced insulation resistance may be suspected. Accordingly, it is possible to accurately diagnose module-to-module imbalance conditions, simultaneously identify their causes, and enable rapid response. In this case, if the imbalance index is negative and a decrease in insulation resistance is suspected, the insulation resistance diagnostic unit (1) can be set to automatically operate at a set time.

[0100] The above power generation prediction unit (3) is configured to predict the power generation of a solar power generation facility, and can predict the power generation for each string. In particular, the power generation prediction unit (3) can increase the accuracy by predicting the power generation by reflecting the specifications and characteristics of each solar module, IV curve data, environmental information, and deterioration rate. To this end, the power generation prediction unit (3) may include a specification information collection module (31), a quantity information collection module (32), a power generation information collection module (33), an environmental information collection module (34), an irradiance information collection module (35), a temperature information collection module (36), a deterioration rate calculation module (37), and a predicted power generation generation module (38).

[0101] The above specification information collection module (31) is configured to collect specification information of solar modules included in a string, and can collect and store manufacturer and product information in advance.

[0102] The above-mentioned number information collection module (32) is configured to collect information on the number of solar modules included in a string, and can generate prediction information by adding the predicted power generation information for each solar module according to the number of solar modules.

[0103] The above power generation information collection module (33) is configured to collect information on the number of days of power generation of a solar power module, and can calculate and collect information on the number of days of power generation by accumulating and storing information on power generation from the time of installation.

[0104] The above environmental information collection module (34) is configured to collect environmental information around the solar module, and can collect information on temperature, humidity, etc.

[0105] The above-mentioned solar irradiance information collection module (35) is configured to collect solar irradiance information reaching a solar module, and can predict power generation using IV curve data according to the collected solar irradiance.

[0106] The above temperature information collection module (36) is configured to collect module temperature information of a solar module, and can collect temperature information measured by a sensor installed in each solar module.

[0107] The above deterioration rate calculation module (37) is configured to calculate the deterioration rate that indicates the degree of deterioration of a solar module, and calculates the deterioration rate based on the number of days of power generation collected by the power generation information collection module (33) by reflecting the degree of deterioration by day determined by the characteristics of each specification of the solar module.

[0108] The above predicted power generation module (38) is configured to predict the power generation of a string, and predicts the power generation by considering IV curve data according to solar irradiance and module temperature, environmental information, and deterioration rate. The prediction of the power generation according to the IV curve data and environmental information can be made experimentally or by analyzing measurement information collected from a solar power generation facility. For example, the correlation can be derived by learning the power generation according to the IV curve data provided by the manufacturer of each solar module by reflecting environmental information and deterioration rate, and the power generation can be predicted using the derived correlation.

[0109] The above power generation measuring unit (4) is configured to measure the power generation of each string, and can calculate the power generation by measuring the voltage and current output from each string.

[0110] The above fault diagnosis unit (5) is configured to diagnose a fault due to a decrease in power generation, and diagnoses a decrease in power generation based on the difference between the predicted power generation and the measured power generation, and in particular, detects a fault type that causes a decrease in power generation based on the area of ​​the area connecting the location on the IV coordinate plane according to the power generation and the point indicating the short-circuit current and open-circuit voltage. To this end, the fault diagnosis unit (5) may include a power generation decrease diagnosis module (51), an Isc area calculation module (52), a Voc area calculation module (53), an area comparison module (54), and a fault cause detection module (55).

[0111] The above power generation decline diagnosis module (51) is configured to diagnose a decline in power generation. If the measured power generation falls short of the predicted power generation by a certain degree or more, it diagnoses a decline in power generation and enables the cause of the decline in power generation to be detected using the area on the IV coordinate plane.

[0112] The above Isc area calculation module (52) is configured to calculate the area of ​​the Isc area formed by the point on the IV coordinate plane where the predicted power generation and measured power generation are indicated and the point (Isc) indicating the short-circuit current, and calculates the area ∆a in the graph shown in Fig. 10. The area ∆a is the area generated according to the difference between the predicted power generation and measured power generation, and a large area of ​​∆a means a decrease in current, i.e., an increase in the series resistance on the string.

[0113] The above Voc area calculation module (53) is configured to calculate the area of ​​the Voc area formed by the point on the IV coordinate plane indicated by the predicted power generation and the measured power generation and the point (Voc) indicating the open circuit voltage, and calculates the area of ​​∆b in the graph illustrated in Fig. 10. The area of ​​∆b is also an area generated according to the difference between the predicted power generation and the measured power generation, and a large area of ​​∆b means a decrease in voltage, i.e., a decrease in parallel resistance in the string.

[0114] The above area comparison module (54) is configured to compare the areas of the Isc area (∆a) and the Voc area (∆b), and depending on which area has a larger area, it can be determined whether the cause of the decrease in power generation is an increase in series resistance or a decrease in parallel resistance.

[0115] The above-described fault cause detection module (55) is configured to detect the cause of the decrease in power generation based on the comparison result by the above-described area comparison module (54). If the area of ​​the Isc area (∆a) is larger than the area of ​​the Voc area (∆b), it can be considered that the decrease in power generation is caused by an increase in series resistance, such as a cable connection condition, a line condition, or shading within the module. If the area of ​​the Isc area (∆a) is smaller than the area of ​​the Voc area (∆b), it can be considered that the decrease in power generation is caused by a decrease in parallel resistance, such as a leakage current, cell cracks, or a decrease in insulation resistance. At this time, the insulation resistance diagnosis unit (1) can be operated. Therefore, it is possible to quickly inspect and respond to the decrease in power generation based on the result detected by the fault cause detection module (55).

[0116] In the above, the applicant has described various embodiments of the present invention, but such embodiments are only examples of implementing the technical idea of ​​the present invention, and any change or modification that implements the technical idea of ​​the present invention should be interpreted as falling within the scope of the present invention.

Claims

1. In an insulation resistance diagnosis system that diagnoses the insulation resistance status of a string of a solar power generation facility, Includes an insulation resistance diagnosis unit that precisely diagnoses whether the insulation resistance of the string has decreased, The above insulation resistance diagnostic unit, A solar power generation facility insulation resistance diagnosis system comprising a voltage application module that applies voltage to a string for a certain period of time, an insulation resistance measurement module that measures insulation resistance at unit time intervals according to the voltage application, a kick index calculation module that calculates a kick index indicating the degree of change in insulation resistance per unit time for a certain period of time, and an abnormality detection module that determines that there is an insulation resistance abnormality when the calculated kick index exceeds a set reference value.

2. In the first paragraph, the insulation resistance diagnosis unit A solar power generation facility insulation resistance diagnosis system characterized by including a diagnosis time setting module that sets a diagnosis time of an insulation resistance status.

3. In the first paragraph, the kick index calculation module A solar power generation facility insulation resistance diagnosis system characterized by calculating a time kick index by the mathematical formula 1 below. (Equation 1) 4. In paragraph 1, the solar power generation facility insulation resistance diagnosis system A solar power generation facility insulation resistance diagnosis system characterized by including a voltage regulation module that allows measurement of insulation resistance while changing voltage in steps.

5. In the fourth paragraph, the kick index calculation module A solar power generation facility insulation resistance diagnosis system characterized by calculating a voltage kick index by the mathematical formula 2 below. (Equation 2) 6. In paragraph 1, the solar power generation facility insulation resistance diagnosis system Includes a module imbalance diagnosis unit that diagnoses imbalance between solar modules in a string, The above insulation resistance diagnostic unit, A solar power generation facility insulation resistance diagnosis system characterized in that it performs an insulation resistance diagnosis when an imbalance due to a decrease in insulation resistance is diagnosed by the above module imbalance diagnosis unit.

7. In paragraph 6, the module imbalance diagnosis unit, A voltage imbalance calculation unit that calculates the degree of voltage imbalance between modules that make up the string, A fluctuation abnormality calculation unit that calculates the abnormality according to the voltage and current fluctuations of the string, A solar power generation facility insulation resistance diagnosis system characterized by including an imbalance detection unit that detects imbalance between modules of a string according to the degree of voltage imbalance and the degree of abnormal fluctuation.

8. In paragraph 7, the voltage imbalance calculation unit A solar power generation facility insulation resistance diagnosis system characterized by including a string voltage measurement module that measures the voltage of power output from a string, a module voltage measurement module that measures the voltage of a specific module within the string, and a voltage imbalance coefficient calculation module that calculates a voltage imbalance coefficient that indicates the degree of voltage imbalance between modules by subtracting a value obtained by multiplying the number of solar modules included in the string by the voltage of the specific module from the string voltage.

9. In paragraph 8, the voltage imbalance calculation unit A solar power generation facility insulation resistance diagnosis system characterized by including a voltage imbalance diagnosis module that compares the voltage imbalance coefficient calculated by the above-mentioned imbalance coefficient calculation module with a reference value and, if the reference value is exceeded, diagnoses a voltage imbalance between modules and executes a fluctuation abnormality calculation unit.

10. In paragraph 8, the above fluctuation abnormality calculation unit A solar power generation facility insulation resistance diagnosis system characterized by including a voltage measurement module that measures the voltage output from a string for a certain period of time, a current measurement module that measures the current output from the string for a certain period of time, and a power variation coefficient calculation module that calculates the value of the ratio of voltage change to current change for the ratio of voltage to current per unit time for a certain period of time and calculates a power variation coefficient that indicates the degree of voltage and current variation by the average value thereof.

11. In the 10th paragraph, the above fluctuation abnormality calculation unit A solar power generation facility insulation resistance diagnosis system characterized by including a coefficient adjustment module that increases the scale while changing the standard for the normal state of the power variation coefficient to 0.

12. In the 11th paragraph, the coefficient adjustment module A solar power generation facility insulation resistance diagnosis system characterized in that the final power variation coefficient is calculated by adjusting the power variation coefficient by mathematical expression 4. (Equation 4) Pf = (1-Pd)*10 (Here, Pf is the adjusted power variation coefficient, and Pd is the initial power variation coefficient) 13. In the 11th paragraph, the imbalance detection unit A solar power generation facility insulation resistance diagnosis system characterized by including a voltage imbalance coefficient loading module for loading a voltage imbalance coefficient, a power variation coefficient loading module for loading a power variation coefficient, an imbalance index calculation module for calculating an imbalance index indicating the degree of output imbalance between modules by multiplying the voltage imbalance coefficient and the power variation coefficient, and an abnormality information diagnosis module for diagnosing an abnormality due to output imbalance between modules of a string based on the calculated imbalance index.

14. In the 13th paragraph, the abnormal information diagnosis module A solar power generation facility insulation resistance diagnosis system characterized in that when the unbalance index is positive, it diagnoses module damage, shading, or contamination, and when the unbalance index is negative, it diagnoses PID, cell cracks, or insulation resistance degradation.

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