KR102076978B1 - The solar energy generation system having the error detecting part - Google Patents

Abstract

According to an embodiment of the present invention, provided is a photovoltaic system which comprises: a solar cell module which generates power from sunlight; a connection board which collects the power generated from the solar cell module in an array unit and transmits the power to an inverter; an inverter which converts the power in the array unit generated by the solar cell module from direct current to alternating current and supplies the power to a load or commercial power; a detection unit which bypasses current to other modules connected to each module to measure the current and resistance of a variable resistor; and a monitoring system receiving values of the current and voltage for a specific resistance value from the detection unit, calculates an I-V curve, and determines types of failure of the solar cell module in accordance with characteristics of the I-V curve. Therefore, by using the I-V curve capable of checking the characteristics of the solar cell module, detailed failure of the photovoltaic system for a building in operation can be diagnosed.

Description

The solar energy generation system having the error detecting part

The present invention relates to a solar power system.

More specifically, it relates to a photovoltaic power generation system having a failure detection unit.

The photovoltaic power generation system for buildings consists of a solar cell module, a connection panel, an inverter, and a monitoring system. The failure of the photovoltaic system occurs mainly in the inverter and the module, and particularly, the failure rate of the inverter is high. There are two types of inverter failures: self-protective faults and faults that can be stopped. That is, since the inverter stops operation when a failure that cannot be solved by its own protection function occurs, the inverter's failure status can be checked in the monitoring system. The failure of the solar cell module is classified into safety problems such as electric power degradation, fire, electric shock, physical hazard, and secondary failure, which are irreversible conditions in normal operation. At this time, problems with pure appearance, failure due to pollution and lightning are not regarded as failures.

Since such a solar cell module shows a power drop, it is difficult to easily identify a failure, and it is difficult to diagnose the failure even with the naked eye, so performance and failure diagnosis through continuous monitoring are necessary.

In the conventional fault diagnosis, the power generation state is divided into a simple power generation normal state, a power generation abnormality (failure), and a stoppage when the power generation efficiency is lower than the standard power generation efficiency and when the measured voltage and the measured current are outside a certain range of the reference voltage and the reference current. . And when measuring the voltage and current for each string, it distinguishes the failed string. In general, in the photovoltaic system in operation, the failure diagnosis of the solar cell module is based on the measured value in order not to affect the operation state.

For the maintenance of the solar cell module, an expert may use a portable I-V curve meter, but this meter has the inconvenience of connecting directly to the circuit of the solar power system whenever the user wants to check the I-V curve. Also, the I-V curve should be checked on a separate screen from the existing monitoring system.

The failure types of the module include peeling, cracking, snail traces, hot spots, bypass diode failure, and potential induced degradation (PID), but this type cannot be diagnosed by conventional failure diagnosis.

An array of solar power systems is a number of modules connected in series or parallel, and a string is a number of modules connected in series. Therefore, the voltage and current vary depending on the coupling type of the array, that is, in series or parallel connection. The I-V curve can be measured by voltage and current by changing the resistance value. However, measuring the I-V curve of a module in a photovoltaic system in operation is not easy because it requires open circuits and short circuits and changes in resistance.

Prior art literature

Republic of Korea Patent Publication No. 2016-6885

The present invention is to provide a solar power system that can measure the I-V curve of the module in the array of the photovoltaic power generation system to solve the above problems, thereby diagnosing a failure.

In an embodiment, a solar cell module that produces power from sunlight, an inverter that converts power produced by the solar cell module from direct current to alternating current and supplies it as a load or commercial power, and power produced by the solar cell module in an array unit A connection panel for collecting and transmitting to the inverter, a detection unit for measuring the current and resistance of the variable resistor by bypassing the current to the other solar cell modules attached to and connected to each of the solar cell modules, and a specific resistance value from the detection unit It provides a photovoltaic power generation system including a monitoring system for receiving the values of the current and voltage for, calculate the IV curve, and determine the type of failure of the solar cell module according to the characteristics of the IV curve.

The detector may include an electronic switch that bypasses current to the other solar cell module, a variable resistor that flows current from the electronic switch, and a control device that adjusts the size of the variable resistor.

An ammeter for measuring the current of the variable resistor and a voltmeter for measuring the voltage of the variable resistor may be further included.

The monitoring system may estimate the I-V curve by instructing the measurement of the I-V curve and receiving current and voltage values for resistance values of the variable resistor.

The monitoring system may determine a failure when the number of times of detecting the abnormal data detected by utilizing the power of the string and the array collected from the connection panel and the inverter exceeds the failure diagnosis rate of the total number of data.

If the monitoring system is determined to have failed, the measured IV curve and the power and voltage of the normal IV curve, the current value, the measured IV curve and the open voltage of the normal IV curve and the measured IV curve and the normal IV curve The type of failure can be determined by comparing the short-circuit current values.

According to the present invention, a detailed failure of a photovoltaic power generation system for a building in operation can be diagnosed using an I-V curve capable of checking the characteristics of the solar cell module.

In addition, through this, the administrator of the solar power system can quickly deal with the failure. In addition, the building owner of a building in which a photovoltaic power generation system is installed can expect energy saving and maintenance cost reduction through an increase in the utilization rate and maintenance efficiency of the photovoltaic power generation system. The present invention can be applied to all small-capacity building solar power systems.

1 is a configuration diagram of a solar power system according to an embodiment of the present invention.
FIG. 2 is a detailed view of the detection unit of FIG. 1.
Figure 3 shows the change in the IV curve of the solar cell module in parallel.
4 shows the IV curve change according to the type of failure.
5 is a flow chart for diagnosing the presence or absence of a fault according to an embodiment of the present invention.
6 is a flowchart for diagnosing a failure type according to the failure result of FIG. 5.
FIG. 7 shows the movement of the curve for correction of the reference IV curve of FIG. 6.

The present invention can be applied to various changes and may have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing each drawing, similar reference numerals are used for similar components.

Terms such as first, second, A, and B can be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from other components. For example, the first component may be referred to as a second component without departing from the scope of the present invention, and similarly, the second component may be referred to as a first component. The term and / or includes a combination of a plurality of related described items or any one of a plurality of related described items.

When an element is said to be "connected" or "connected" to another component, it is understood that other components may be directly connected to or connected to the other component, but other components may exist in the middle. It should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that no other component exists in the middle.

The terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "include" or "have" are intended to indicate the presence of features, numbers, steps, actions, components, parts or combinations thereof described herein, one or more other features. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains. Terms such as those defined in a commonly used dictionary should be interpreted as having meanings consistent with meanings in the context of related technologies, and should not be interpreted as ideal or excessively formal meanings unless explicitly defined in the present application. Does not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a configuration diagram of a photovoltaic power generation system according to an embodiment of the present invention, and FIG. 2 is a detailed view of the detection unit of FIG. 1.

The solar power generation system including the failure detection unit 500 of the present invention, as shown in Figure 1, the solar cell module 100 for producing power from sunlight, the array of power produced by the solar cell module 100 The connection panel 200 that is collected in units and transmitted to the inverter 300, the inverter 300 that converts the electric power produced by the solar cell module 100 from DC to AC, and supplies it as a load or commercial power, a solar cell module ( 100) power generation of the solar power system based on data transmitted from the detection unit 500, the connection panel 200, the inverter 300, and the detection unit 500 that collects the measured data and transmits it to the monitoring system 400 It comprises a monitoring system 400 for monitoring the current status, and controlling the operation.

A plurality of solar cell modules 100 are connected and installed to form a solar cell array, a module thermometer is located at the rear of the representative solar cell module 100, and a thermometer for measuring the air temperature around the solar cell module 100, and solar radiation An insolation meter is installed to measure.

The solar power system of the present invention includes a detector 500 for calculating an I-V curve by measuring voltage and current applied to a module in a string and another module connected between modules, as shown in FIG. 2.

2, the detector 500 includes an electronic switch MS, a variable resistor VR, and a control device 510 for adjusting the size of the variable resistor.

The electronic switch (MS) serves to bypass the circuit connected to the other module toward the variable resistor (VR).

The variable resistor VR is a slide-type variable resistor, which flows a current from the electromagnetic switch MS, and adjusts the size of the variable resistor with a control device such as a linear motor.

At this time, an ammeter for measuring the current flowing through the variable resistor (VR) and a voltmeter for measuring the voltage applied to the variable resistor (VR) are installed, and the capacity of the variable resistor (VR) is the module open voltage at STC. Calculate to the maximum considering. And the measurement of the I-V curve starts when the size of the variable resistor is maximum.

The current applied to the other module through the circuit of the detector 500 flows to the variable resistor VR to measure the current and voltage for the resistance value of the variable resistor VR to estimate the I-V curve.

At this time, when the resistance value of the variable resistor VR is 0, the current value flowing may be set as a short-circuit current, and when the resistance value is infinite, the voltage applied to the variable resistor VR may be set as an open voltage.

The I-V curve may have characteristics as shown in FIGS. 3 and 4.

3 shows a change in the I-V curve of the solar cell module in series and parallel, and FIG. 4 shows a change in the I-V curve according to the type of failure.

As shown in FIG. 3, the array of the photovoltaic system is a plurality of modules connected in series or in parallel, and when IV curves for one solar module are defined as f1, the current when two solar modules are connected in series is It is the same but shows the f2 curve where the voltage is doubled, and when two solar modules are connected in parallel, the voltage is the same and the f3 curve where the current is doubled.

The IV curve drawn by the open circuit, the short circuit current, the measurement voltage, and the measurement current detected by the detection unit 500 is a failure type, such as Delamination, Crack, Snail Tails, as shown in FIG. 4 of the solar cell module. or Snail traces), hot spots, bypass diode failures, and PID (potential-induced degradation).

That is, as shown in FIG. 4, it is possible to determine which fault belongs to a general I-V curve according to a change in slope and an inflection point, a short circuit current, and an open voltage within the detected and estimated I-V curve.

The information about the current and voltage of the circuit of the detector 500 is received by the monitoring system 400, the measured IV curve is estimated, and the measured IV curve and the normal IV curve are simultaneously displayed on the monitoring screen to compare and compare the modules. Diagnose the failure type.

Hereinafter, a method of performing a fault diagnosis will be described with reference to FIGS. 5 and 6.

5 is a flow chart for diagnosing the presence or absence of a fault according to an embodiment of the present invention.

Referring to FIG. 5, when monitoring is started in the monitoring system, the values of measured solar radiation (G _m ) and maximum power (P _{max, m} ) are collected and stored (S10).

Here, G _m is the measured solar radiation, P _{max, m} is the measured maximum power, G _s is the reference solar radiation starting diagnosis, R _f is the power generation abnormality rate, R _c is the failure diagnosis rate, P _{max, mt} is the solar radiation quantity. Measured maximum power that satisfies the condition, P _{max, s} is the reference maximum power, P _{max, mf} is the maximum measured power that is abnormal in power generation, C _f is the number of abnormal data in power generation (maximum measured power that is abnormal in power generation), C _t is the total data It indicates the number of measured maximum power) that satisfies the solar irradiation condition.

The reference value for diagnosing the presence or absence of a failure is to input a set value as the value of the starting radiation dose (G _s ), the power generation abnormality ratio (R _f ), and the failure diagnosis ratio (R _c ) (S20).

By setting the utilization period of the measured solar radiation and the maximum power, which are the past data collected, the data of the corresponding period is used for diagnosis of the presence or absence of a failure (S30).

For the measured maximum power (P _{max, mt} ) that satisfies the insolation condition, it refers to the maximum measured power that satisfies the insolation condition among the measured maximum powers in the set period, and in the insolation condition, the measured insolation amount (G _m ) is the diagnosis start insolation amount (G _{It has a} value greater than _s ) (S40).

The reference maximum power (P _{max, s} ) utilizes the average value of the measured maximum power, which is the same insolation, or the value of the general power generation calculation formula using the module area, number, and efficiency (S50).

On the other hand, since the basic information provided by the module manufacturer, such as efficiency and maximum power, is different from the actual module installation site and conditions as a result of STC, it is recommended to use it at the initial stage of installation without historical data.

The measured maximum power (P _{max, mf} ) detected as an abnormality in power generation means that the measured maximum power (P _{max, mt} ) that satisfies the solar irradiation condition is smaller than the power generation abnormality ratio (R _f ) of the reference maximum power (S60) ).

The number of abnormal data (C _f ) and the total number of data (C _t ) are counted and detected by counting the maximum power (P _{max, mf} ) measured over power generation and the maximum measured power (P _{max, mt} ) that meets the solar radiation condition. (S70), comparing the number of data to distinguish the failure and normal (S80).

If the number of abnormal data (C _f ) is not greater than the failure diagnosis rate (R _c ) of the total number of data (C _t ), it is judged as normal (S90), and if it is large, it is judged as a failure because it is a continuous decrease in power generation. And diagnose the failure type (S100).

When diagnosed as a failure, the monitoring system 400 estimates the I-V curve with current and voltage values for various collected resistance values.

Specifically, referring to FIG. 6, I-V curves are estimated by collecting measured data to diagnose a failure type (S101).

Here, V _{oc, m} is the measurement open voltage, I _{sc, m} is the measurement short-circuit current, V _{n, m} is the nth measurement voltage, I _{n, m} is the nth measurement current, R _v is the open voltage abnormality ratio, R _i is the short-circuit current error ratio, R _e is the error error ratio, R _ce1 is the non-uniform separation and the failure type classification ratio that distinguishes cracks and snail traces, R _ce2 is the bypass diode failure and the failure type classification ratio that distinguishes PID Shows. V _{oc, s} is a reference open voltage, I _{sc, s} is a reference short-circuit current, V _{n, s} is an n-th reference voltage, and I _{n, s} is an n-th reference current, respectively. In addition, IP _m is the point where the increase and decrease in power in the measurement IV curve begins, C _ip is the number of power change points in the measurement IV curve, and V _{n, sr} is the reference IV curve based on the measured short-circuit current or open voltage. The corrected n-th reference voltage, I _{n, sr} is the n-th correction reference current, E _n is the error ratio between the correction reference current and the measured current, and C _e1 is an error greater than the error ratio in the data to the extracted first power change point. Is the number of error data showing, C _n1 is the number of data up to the first power change point extracted. C _e2 is the number of error data showing an error greater than the error ratio, and C _n is the total number of measurement data.

The monitoring system 400 classifies the failure type (uniform peeling, non-uniform peeling, bypass diode failure, hot spot, crack, snail trace, PID) according to the difference between each measured value and the reference value.

First, as a set reference value for diagnosing a failure type, an open voltage abnormality ratio (R _v ), a short circuit current abnormality ratio (R _i ), R _e is an error anomaly ratio, and R _ce is a failure type classification ratio (S102).

Set the utilization period of the measured open voltage, short-circuit current, n-th voltage, and current, which are the collected past data, and use the data of the corresponding period to calculate the reference value (S103).

The reference open voltage, short-circuit current, n-th voltage and current are calculated by using the average values of the measured open-circuit voltage, short-circuit current, n-th voltage and current, which are the same amount of insolation, and estimate the I-V curve (S104).

It is determined whether the measured open voltage (V _{oc, m} ) is smaller than the open voltage abnormality ratio (R _v ) of the reference open voltage (V _{oc, s} ) (S105).

If the measured open voltage (V _{oc, m} ) is not less than the open voltage abnormality ratio (R _v ) of the reference open voltage (V _{oc, s} ), the measured short-circuit current (I _{sc, m} ) and the reference short-circuit current (I _{sc, s} ) are compared (S106).

When the measured short-circuit current (I _{sc, m} ) is not smaller than the short-circuit current abnormality ratio (R _i ) of the reference short-circuit current (I _{sc, s} ), it is determined as a hot spot (S118).

When the measured short-circuit current (I _{sc, m} ) is less than the short-circuit current abnormality ratio (R _i ) of the reference short-circuit current (I _{sc, s} ), the increase or decrease in power in the IV curve due to the increase or decrease in the nth measured power The starting point (IP _m ) is extracted as follows (S107).

The number of points (C _ip ) of power change points is detected by counting the number of points (IP _m ) where the increase and decrease of power in the measured IV curve extracted in this way (S108), and the number of power change points (C _ip ) It is determined whether is greater than one (S110).

When the measured short-circuit current (I _{sc, m} ) is less than the short-circuit current abnormality ratio (R _i ) of the reference short-circuit current (I _{SC, s} ), and the number of power change points (C _ip ) in the IV curve is not greater than one , It is judged to be uniform peeling (S109).

When the measured short-circuit current (I _{sc, m} ) is less than the short-circuit current abnormality ratio (R _i ) of the reference short-circuit current (I _{SC, s} ), and the number of power change points (C _ip ) in the IV curve is greater than one, Based on the measured short-circuit current (I _{sc, m} ), the reference IV curve is moved to calculate the corrected n-th reference voltage (V _{n, sr} ) and current (I _{n, sr} ) (S111).

The error ratio (E _n ) between the calculated correction reference current (I _{n, sr} ) and the measured current (I _{n, m} ) is calculated (S112), and data showing an error ratio greater than the error anomaly ratio (R _e ) Calculate the number (C _e1 ) of (S113).

It is determined whether the number of error data C _e1 showing an error ratio greater than the error anomaly ratio R _e is smaller than the failure type classification ratio R _ce1 of the total data number C _n1 (S114).

The measured short-circuit current (I _{sc, m} ) is less than the short-circuit current abnormality ratio (R _i ) of the reference short-circuit current (I _{SC, s} ), the number of power change points (C _ip ) in the IV curve is greater than one, and the error If the number of error data (C _e1 ) showing an error ratio greater than the error ratio is not smaller than the failure type classification ratio (R _ce1 ) of the total number of data (C _n1 ), it is determined as non-uniform separation (S120), and when it is small , It is determined as a crack and a snail trace (S121).

On the other hand, when the measured open voltage (V _{oc, m} ) is smaller than the ratio of the open voltage abnormality (R _v ) of the reference open voltage (V _{oc, s} ), the reference IV curve is _drawn based on the measured open voltage (V _{oc, m} ). The n-th reference voltage (V _{n, sr} ) and current (I _{n, sr} ) corrected by moving are calculated (S115).

The error ratio (E _n ) between the calculated correction reference current (I _{n, sr} ) and the measured current (I _{n, m} ) is calculated (S116), and data showing an error ratio greater than the error anomaly ratio (R _e ) The number C _e of is calculated (S117).

It is determined whether the number of error data C _e showing an error ratio greater than the error anomaly ratio R _e is smaller than the failure type classification ratio R _ce of the total number of data C _n (S118).

The total number of error data (C _e ) in which the measured open voltage (V _{oc, m} ) is less than the open voltage anomaly ratio (R _v ) of the reference open voltage (V _{oc, s} ) and shows an error ratio greater than the error anomaly ratio is total If it is not smaller than the failure type classification ratio R _ce of the data number C _n , it is determined as PID (S122).

The total number of error data (C _e2 ) in which the measured open voltage (V _{oc, m} ) is less than the open voltage anomaly ratio (R _v ) of the reference open voltage (V _{oc, s} ) and shows an error ratio greater than the error anomaly ratio is total If it is smaller than the failure type classification ratio R _ce2 of the data number C _n2 , it is determined as a bypass diode failure (S123).

As described above, by comparing power, open voltage and short-circuit current, measured voltage, and measured current, it is possible to diagnose which of the faults corresponds to the fault and notify the manager.

FIG. 7 shows the movement of the reference I-V curve for calculating the correction reference voltage and current of FIG. 6.

As described above, the detailed failure of the photovoltaic system for a building in operation can be diagnosed and repaired and managed according to the type of failure using the I-V curve that can confirm the characteristics of the solar cell module.

In the above, preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, but these are only examples.

Those skilled in the art will appreciate that various modifications and changes can be made to the present invention without departing from the spirit and scope of the invention as set forth in the claims below.

Claims (6)

Solar cell module that produces power from sunlight,
An inverter that converts the power produced by the solar cell module from direct current to alternating current and supplies it as a load or a commercial power source,
The connection panel that collects the power produced by the solar cell module in an array unit and transmits it to the inverter,
A detection unit for measuring the current and resistance of the variable resistor by bypassing the current to the other solar cell modules attached to and connected to each of the solar cell modules, and
The ratio of the number of abnormal data that is the number of abnormal data that is the number of measured maximum powers detected as having an abnormality in power generation to the total number of data that is the number of measured maximum powers that satisfies the solar irradiation condition by obtaining the maximum power from the inverter is the maximum. If it is greater than the rate of power generation abnormality, it is judged to be a failure by judging a continuous drop in power generation, and in the case of a failure, an IV curve is calculated from the current and voltage from the detection unit, and the calculated change in slope of the IV curve, It is diagnosed as a type of failure among peeling, cracking, snail trace, hot spot, bypass diode failure, PID according to the change of inflection point, short circuit current and open voltage, and alarms the manager. Monitoring system
Solar power system comprising a. According to claim 1,
The detection unit
Electronic switch that bypasses the current to other solar cell modules,
A variable resistor that flows current from the electromagnetic switch, and
Control unit for sizing the variable resistor
Containing
Solar power system. According to claim 2,
Ammeter to measure the current of the variable resistor, and
Voltmeter to measure the voltage of the variable resistor
Solar power system further comprising a. delete delete According to claim 1,
The monitoring system
If it is determined that a malfunction has occurred,
Determine the type of failure by comparing the measured IV curve and the power and voltage of the normal IV curve, the current value, the open voltage of the measured IV curve and the normal IV curve, and the short-circuit current values of the measured IV curve and the normal IV curve, respectively. Solar power system.

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