CN114710115A - Photovoltaic array fault defect diagnosis system and method - Google Patents
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Abstract
The invention discloses a photovoltaic array fault defect diagnosis system and method in the technical field of photovoltaic cell arrays, which comprises the following steps: collecting the voltage and current values of each photovoltaic cell string in the photovoltaic array; comparing the acquired voltage values, and finding out the battery string with the minimum voltage value and the current and voltage values of the battery string; calculating the difference value between the voltage value of the battery string with the minimum voltage value and the voltage value under normal operation, and judging whether the difference value exceeds the normal deviation; when the difference value does not exceed the normal deviation, the voltage and current values of all the photovoltaic cell strings in the photovoltaic array are collected again to continue monitoring; and when the difference exceeds the normal deviation, putting the battery string with the minimum voltage value into the suspected fault group to judge the secondary fault battery string. The method can basically judge the type and the position of the fault by combining the traditional voltage and current positioning method, the time tracking method and the photovoltaic cell diagnosis model.
Description
Technical Field
The invention relates to a photovoltaic array fault defect diagnosis system and method, and belongs to the technical field of photovoltaic cell arrays.
Background
With the popularization of green energy, the solar power generation technology develops rapidly. The physical principle of the solar power generation technology is that solar energy irradiated on a photovoltaic panel is converted into direct current electric energy by utilizing a photovoltaic effect, and then the direct current electric energy is converted into various types of electric energy through a power electronic device for load use. In the process of solar power generation, a photovoltaic cell is a core component in the power generation process. However, in the actual use process of the photovoltaic panel, bird, cloud, dust and other shelters are inevitably generated, and the shelters form local shadows on the photovoltaic panel. In addition, the photovoltaic cell has defects of hidden cracks, broken grids and the like, and the components generate heat locally during working, so that glass of the photovoltaic panel can be broken, welding spots can be melted, and the array can be burnt even after the components work for a long time.
International photovoltaic quality assurance special action group research by the united states national renewable energy laboratory organization shows that of the typical hot spot problems of these actually operating photovoltaic power stations, 3 classes are more common, class a: significant temperature difference between cells, class B: single string battery performance failure, class C: the glass and the battery are cracked. The temperature difference of different battery pieces in the photovoltaic panel with the A-type problem is not large, the battery is usually generated by hidden cracking of the battery caused by the assembly carrying and installing processes, and the power reduction range of the A-type problem is about 5% -8% in the indoor solar simulator test; the performance failure of a single string of cells in a photovoltaic panel with the B-type problem, which causes about 30% of power loss, is usually caused by that a component with the A-type problem runs outdoors for a long time and the performance failure of the single string of cells is caused to be converted into a component with the B-type problem after several months or longer; the photovoltaic module with the C-type problems causes rapid local temperature rise in a short time under larger reverse bias leakage current or reverse bias voltage, and a battery and a panel are directly burnt in a short time (for several days), so that the problems are mainly caused by current mismatch caused by shielding or local shadow, and at the moment, a bypass diode is conducted and generates a large amount of heat, and the performance is attenuated and loses efficacy for a long time; the photovoltaic cells are then subjected to higher reverse bias voltages without protection, eventually causing the cells to burn out.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a photovoltaic array fault defect diagnosis system and method, which can basically judge the type and position of a fault by combining the traditional voltage and current positioning method, time tracking method and photovoltaic cell diagnosis model.
In order to achieve the purpose, the invention is realized by adopting the following technical scheme:
in a first aspect, the present invention provides a method for diagnosing a fault defect of a photovoltaic array, including:
collecting the voltage and current values of each photovoltaic cell string in the photovoltaic array;
comparing the collected voltage values, and finding out the battery string with the minimum voltage value and the current voltage value of the battery string;
calculating the difference value between the voltage value of the battery string with the minimum voltage value and the voltage value under normal operation, and judging whether the difference value exceeds the normal deviation;
when the difference value does not exceed the normal deviation, the voltage and current values of all the photovoltaic cell strings in the photovoltaic array are collected again to continue monitoring;
when the difference exceeds the normal deviation, putting the battery string with the minimum voltage value into a suspected fault group to judge the secondary fault battery string;
when the secondary fault battery string is judged and determined, acquiring the temperature and the light intensity of the photovoltaic battery, positioning the fault battery and calculating the resistance estimation value of the photovoltaic battery by combining a photovoltaic array parameter estimation model;
and comparing the estimated value of the resistance of the photovoltaic cell with a normal value, and judging the fault type of the photovoltaic cell.
Further, when the difference exceeds the normal deviation, the battery string with the minimum voltage value is placed in a suspected fault group for secondary fault battery string judgment, and the method comprises the following steps:
continuously collecting the voltage and current values of the photovoltaic cells in the suspected fault group for three times, wherein the time interval of each collection is two hours;
calculating the difference value between the voltage value of the photovoltaic cell in the third suspected fault group and the voltage value under normal operation;
when the photovoltaic cells in the suspected fault group do not continuously exceed the normal deviation for three times, the voltage and the current values of the photovoltaic cells in the suspected fault group are continuously collected for three times again for detection;
and when the photovoltaic cells in the suspected fault group continuously exceed the normal deviation for three times, determining the photovoltaic cells in the suspected fault group as the fault cell strings.
Further, the estimated photovoltaic cell resistance value is:
in the formula, Rs、RshAre estimated values of series and parallel resistances respectively, A is a curve fitting constant, UTIs a thermal voltage, ImIs the maximum current, IscFor short-circuit current, UocIs open circuit voltage, UmIs the maximum voltage.
Further, the maximum current, the short-circuit current, the open-circuit voltage and the maximum voltage are obtained through detection.
7. Further, the curve fitting constant is:
wherein A is a curve fitting constant, Uoc1、Isc1Open circuit voltage and short circuit current at ambient conditions, Uoc2、Isc2Open circuit voltage and short circuit current, U, under ambient conditions twoTIs a thermal voltage.
Further, the thermal voltage is:
in the formula of UTK is a boltzmann constant, T is a battery thermodynamic temperature, and q is an electron charge amount.
Further, the normal deviation is an artificial preset value.
In a second aspect, the present invention provides a photovoltaic array fault diagnosis system, including:
an acquisition module: the photovoltaic array is used for collecting the voltage and current values of each photovoltaic cell string in the photovoltaic array;
a positioning module: the battery string is used for comparing the acquired voltage values and finding out the battery string with the minimum voltage value and the current voltage value of the battery string;
a primary judgment module: the device is used for calculating the difference value between the voltage value of the battery string with the minimum voltage value and the voltage value under normal operation and judging whether the difference value exceeds the normal deviation;
a reacquisition module: the voltage and current values of all the photovoltaic cell strings in the photovoltaic array are collected again to continue monitoring when the difference value does not exceed the normal deviation;
a secondary judgment module: the battery string with the minimum voltage value is placed in a suspected fault group to judge a secondary fault battery string when the difference value exceeds the normal deviation;
a parameter calculation module: the photovoltaic array parameter estimation model is used for collecting the temperature and the light intensity of the photovoltaic cell when the secondary fault cell string is judged and determined, positioning the fault cell and calculating the resistance estimation value of the photovoltaic cell in combination with the photovoltaic array parameter estimation model;
a fault type judgment module: and the method is used for comparing the estimated value of the resistance of the photovoltaic cell with a normal value and judging the fault type of the photovoltaic cell.
In a third aspect, the invention provides a photovoltaic array fault and defect diagnosis device, which comprises a processor and a storage medium;
the storage medium is to store instructions;
the processor is configured to operate in accordance with the instructions to perform the steps of the method according to any of the above.
In a fourth aspect, the invention provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps of any of the methods described above.
Compared with the prior art, the invention has the following beneficial effects:
the diagnosis method is provided for solving the problem that the fault position cannot be accurately positioned when the hot spot fault occurs in the photovoltaic array, and the type and the position of the fault can be basically judged by combining the traditional voltage and current positioning method, the time tracking method and the photovoltaic cell diagnosis model; the method can accurately position the position of hot spot fault occurrence, provides an effective diagnosis method for photovoltaic array fault diagnosis, and can be further used for popularization and application of photovoltaic power stations.
Drawings
Fig. 1 is a diagram of a single photovoltaic cell model according to an embodiment of the present invention: (a) generating a photo-generated current mechanism diagram for the photovoltaic cell, (b) an equivalent circuit model for a single photovoltaic cell;
fig. 2 is a schematic diagram of a series connection and a parallel connection of m × n photovoltaic cells according to an embodiment of the present invention: (a) a schematic diagram of m photovoltaic cells connected in series, (b) a schematic diagram of n photovoltaic cells connected in parallel;
fig. 3 is an m × n photovoltaic cell array model provided in the first embodiment of the present invention: (a) a physical model of the mxn array of photovoltaic cells, (b) an equivalent circuit model of the mxn array of photovoltaic cells;
FIG. 4 is a reverse bias equivalent circuit model of a single photovoltaic cell caused by hot spot phenomenon of the mxn photovoltaic cell array in FIG. 3;
fig. 5 is a flow chart of diagnosing a fault defect of a photovoltaic array according to an embodiment of the present invention;
fig. 6 is a thermal spot fault versus 1 output characteristic curve of a 4 × 1 pv array according to an embodiment of the present invention: (a) a schematic diagram of a 4 × 1 photovoltaic cell array, (b) a U-I characteristic curve of the 4 × 1 photovoltaic cell array, and (c) a P-U characteristic curve of the 4 × 1 photovoltaic cell array.
Detailed Description
The technical scheme of the invention is further explained in detail by combining the attached drawings: the embodiments described herein are only directed to a method for diagnosing a fault and a defect in a photovoltaic array, and in order to further illustrate the technical means and effects of the present invention adopted to achieve the predetermined objects, the following detailed description, the structures, the features and the effects thereof will be provided in conjunction with the accompanying drawings and the preferred embodiments.
The first embodiment is as follows:
a photovoltaic array fault defect diagnosis method comprises the following steps:
step 1: through voltage, current sensor, gather the voltage, the current value of each photovoltaic cell cluster, to the output current, the voltage of the photovoltaic cell cluster that m photovoltaic cell subassembly series connection formed:
Iout＝Ii (1)
in the formulae (1) and (2), IoutIs the total output current, U, of the photovoltaic cell stringoutIs the total output voltage of the photovoltaic cell string, m is the number of rows of photovoltaic cells, IiIs the current of the photovoltaic cell module of the ith row, UiI is the voltage of the photovoltaic cell assembly in the ith row, 1, 2.
The output current and voltage of a photovoltaic array formed by connecting n rows of photovoltaic cells in series and parallel are as follows:
Uout＝Uj (4)
in the formulae (3) and (4), IoutTotal output current, U, of an array of photovoltaic cells formed for n series-parallel connection of photovoltaic cellsoutFor the total output voltage of the photovoltaic cell array formed in parallel, n is the number of photovoltaic cell columns, IjIs the current of the photovoltaic cell string of the jth column, UjJ is the voltage of the photovoltaic cell string in the jth column, and j is 1, 2.
Under normal conditions, the currents flowing through the n parallel battery strings are equal, and the current on the battery assembly is as follows:
in the formula (5), IijIs the current flowing through the ith row and jth column battery pack, IoutThe total output current of a photovoltaic cell array formed by connecting n rows of photovoltaic cells in series and parallel is obtained, n is the number of rows of photovoltaic cells, i is the row number of the series photovoltaic cell assembly, and i is more than or equal to 1 and less than or equal to m; j is the serial number of the parallel photovoltaic cell assembly, and j is more than or equal to 1 and less than or equal to n.
Step 2: and comparing the collected voltage values, and searching the column of the battery string with the minimum voltage value.
When a photovoltaic array fails, the output current and the output voltage of the photovoltaic array must change. If the battery in the r-th row and the t-th column has a fault (r is more than or equal to 1 and less than or equal to m, t is more than or equal to 1 and less than or equal to n), the following are provided:
Urt＜Uit (6)
in formula (6), UrtIs the output voltage of the failed battery pack of the t-th column, UitThe output voltage of the battery pack in the t-th row in which no failure occurred is i ≠ t.
And step 3: calculating the voltage value U of the battery string with the minimum voltage amplitude in the step 2minThe difference value delta U between the voltage value U and the voltage value U under normal operation is equal to U-UminJudging whether the difference value exceeds a preset normal deviation, wherein the normal deviation is preset manually according to experience, and the set values of different photovoltaic systems are different; if the normal deviation is not exceeded, returning to the step 1 to continue monitoring; if the normal deviation is exceeded, the battery string is placed in a suspected faulty group.
And 4, step 4: monitoring voltage and current values of photovoltaic cells in a suspected fault group every 2 hours; if the photovoltaic cell string is monitored to be placed in a suspected fault group for 3 times, the cell string can be determined to be a fault cell string.
And 5: the method comprises the following steps of collecting the ambient temperature and the illumination intensity of the fault battery string and carrying out a photovoltaic array distinguishing process:
the equivalent output model of a single photovoltaic cell is equivalent to a single-diode equivalent circuit model, as shown in fig. 1 (b). When the reverse avalanche breakdown effect is considered, a mathematical model of the output characteristics of a single photovoltaic cell can be derived as follows:
in formula (7), U, I represents the output voltage and current of the photovoltaic cell, IphIs a photo-generated current, IoIs the reverse saturation current of the equivalent diode, q is the electron charge amount, A is the curve fitting constant, k is the Boltzmann constant, T is the thermodynamic temperature of the battery, Rs、RshEquivalent series and parallel resistance values, a and b are avalanche breakdown characteristic constants, UbrIs the reverse avalanche breakdown voltage.
A single photovoltaic cell is packaged into a whole through series and parallel connection, and is packaged into a photovoltaic module structure with m rows and n columns by adopting an SP structure, and the specific structure is shown in figure 3 (a); assuming that the electrical parameters of the photovoltaic cells of the entire module structure are identical, from the equivalent circuit diagram of the mxn photovoltaic module in fig. 3(b), the mathematical model of the photovoltaic array can be derived as:
in formula (8), U, I represents the output voltage and current of the photovoltaic cell, IphIs a photo-generated current, IoIs the reverse saturation current of the equivalent diode, q is the electron charge amount, A is the curve fitting constant, k is the Boltzmann constant, T is the thermodynamic temperature of the battery, Rs、RshThe resistance values of the equivalent series resistor and the equivalent parallel resistor are respectively, and a and b are avalanche breakdown characteristic constants; u shapebrFor reverse avalanche breakdown voltage, m is lightThe number of the rows of the photovoltaic cells is n, and the number of the columns of the photovoltaic cells is n;
by collecting the current I flowing through m battery components on each battery stringijVoltage UijJudging the position of the battery string with the fault; when a photovoltaic array fails, the output current and the output voltage of the photovoltaic array must change. If the battery assembly in the r-th row and the t-th column has a fault (r is more than or equal to 1 and less than or equal to m, t is more than or equal to 1 and less than or equal to n), the following steps are provided:
Urt＜Uit (9)
in formula (9), UrtIs the output voltage of the failed battery pack of the t-th column, UitI ≠ r is the output voltage of the battery pack in the t-th column in which no failure has occurred.
According to the volt-ampere characteristic curve of the photovoltaic cell, the other parallel branches except the t column output current IijWill rise. At this time, the output voltage and the output current of the battery string with the fault are smaller than those of other battery strings, and the battery string with the fault can be located at this time.
In order to distinguish trouble of fault discrimination caused by different factors, a time tracking method can be adopted to judge the fault occurrence degree, the accuracy of model discrimination is improved, and the current and voltage values I on a fault t column are collected every 2 hourst、UtTo determine the degree of the failure of the photovoltaic cell, a specific implementation flow is shown in fig. 5.
For accurately positioning the position of the fault and estimating the photovoltaic cell series and parallel resistances of the fault column as shown in fig. 5, the specific steps are as follows:
in the fault column battery string, the reverse avalanche breakdown effect is ignored, and the current equation of a single photovoltaic cell can be obtained as follows:
in the formula (10), IphIs a photo-generated current, IoIs the reverse saturation current of the equivalent diode, q is the electron charge amount, A is the curve fitting constant, k is the Boltzmann constant, T is the thermodynamic temperature of the battery, U, I are light respectivelyOutput voltage and current of the volt-age battery, Rs、RshThe resistance values of the series resistor and the parallel resistor are respectively;
when the component is short-circuited, substituting U-0 and I-IscAt this time, the current I flowing through the equivalent diodeoIs approximately equal to 0 and can be ignored, so that the short-circuit current IscCan be approximately simplified as:
in the formula (11), IscFor short-circuit current, IphIs a photo-generated current, Rs、RshThe resistance values of the series resistor and the parallel resistor are respectively;
when the assembly is opened, substituting I ═ 0, U ═ UocShort-circuit current IscCan be approximately simplified as:
in the formula (12), IscFor short-circuit current, IoIs the reverse saturation current of the equivalent diode, q is the electron charge amount, A is the curve fitting constant, k is the Boltzmann constant, T is the thermodynamic temperature of the battery, UocIs an open circuit voltage, RshIs the resistance value of the parallel resistor;
when the module is at the maximum power point, substituting I-Im，U＝UmMaximum current ImCan be approximately simplified as:
in the formula (13), ImIs the maximum current, IoIs the reverse saturation current of the equivalent diode, q is the electron charge amount, A is the curve fitting constant, k is the Boltzmann constant, T is the thermodynamic temperature of the battery, UmIs the maximum voltage, ImIs the maximum current, Rs、RshThe resistance values of the series resistor and the parallel resistor are respectively;
according to (dU/dI) & gtdoes not countP＝Pm＝-Um/ImDeriving equation (13) at the point where the photovoltaic is at maximum power, we can:
in formula (14), UmIs the maximum voltage, ImIs the maximum current, Rs、RshAre respectively series resistance value and parallel resistance value, UTIs a thermal voltage, IscIs a short circuit current;
wherein, UTThe expression is thermal voltage:
in the formula (15), k is a boltzmann constant, T is a battery thermodynamic temperature, and q is an electron charge amount; the calculation formula of the reverse saturation current of the diode at the standard temperature is as follows:
in the formula (16), IorIs in a standard environment (1000W/m)2Reverse saturation current of equivalent diode, I, at 25 deg.CscrFor short-circuit current under standard conditions, UocrFor open circuit voltage under standard conditions, UTIs a thermal voltage;
the ideality factor a for a diode reflects the loading capacity of the carriers inside the photovoltaic cell, is not affected by environmental parameters, and therefore can be expressed as:
in the formula (17), A is a curve fitting constant which reflects the maximum load capacity of the array to the carriers and is not influenced byThe influence of the environmental parameter is approximately between 1 and 2. U shapeoc1、Isc1Open circuit voltage and short circuit current under ambient conditions, Uoc2、Isc2Open circuit voltage and short circuit current, U, under ambient conditions twoTIs a thermal voltage.
When the resistance value of the series resistor is estimated, neglecting the parallel resistor when the photovoltaic cell is in the maximum power state; for estimating the resistance of the parallel resistor, the series resistor is ignored when the photovoltaic cell is in an open circuit state. Therefore, the estimated values of the series and parallel resistances in the photovoltaic cell are:
in the formulae (18) and (19), Rs、RshAre estimated values of series and parallel resistances respectively, A is a curve fitting constant, UTIs a thermal voltage, ImIs the maximum current, IscFor short-circuit current, UocIs open circuit voltage, UmAnd the maximum voltage is obtained by detecting the maximum current, the short-circuit current, the open-circuit voltage and the maximum voltage.
And 6: and comparing the obtained estimated value of the resistance of the photovoltaic cell with a normal value, and judging the severity of the fault.
And 7: and determining a fault battery string, arranging maintenance personnel to go to maintenance, and removing the fault.
In this embodiment, in order to show the influence of the hot spot effect on the output characteristics of the photovoltaic array, the simulation platform of the present invention builds a model for 1 photovoltaic array of 4 × 1, and the parameters of a single photovoltaic cell are: open circuit voltage Uoc36.6V, short-circuit current IscIs 7.84A; at the maximum power point UmIs 29V, ImIt was 7.35A. Suppose that the 1 st and 2 nd photovoltaic cells of the string are not shadowed by the photovoltaic cellsLoud sound with illumination intensity of SrThe light intensity of the 3 rd cell was 0.75SrThe 4 th cell had an illumination intensity of 0.5SrAs shown in fig. 6 (a).
The output voltage and current of each photovoltaic cell should be very close without being affected by shadows and neglecting the influence of ambient temperature; when the photovoltaic cell is influenced by environmental shadow, the output current of the photovoltaic cell is smaller than the output current of other photovoltaic cells, and the photovoltaic cell is short-circuited by the bypass diode at the moment, so that the battery module can output voltage only when the branch current of the photovoltaic cell is smaller than the maximum current which can be sent by a fault photovoltaic cell. At this time, the output voltage of the series branch can be expressed as:
in the formula (20), SrIs standard illumination intensity and has a value of 1000W/m2；SiThe actual illumination intensity on the ith photovoltaic module in the serial branch; u shapeiIs the output voltage of the photovoltaic module. When S isi>SrWhile, UiValue according to illumination intensity SiChange by change;
at this time, according to the fault defect diagnosis process shown in fig. 5, the faulty photovoltaic cell assembly in the faulty cell string can be located, and the U-I and P-U output characteristic curves shown in fig. 6(b) and 6(c) are obtained.
When the battery string works in the interval 1, the battery output current I influenced by the shadowsjThe working current I is smaller than that of the current branch, so that the 3 rd photovoltaic cell and the 4 th photovoltaic cell are both short-circuited by the bypass diode, and only the 1 st photovoltaic cell and the 2 nd photovoltaic cell work normally at the moment; when the battery string works in the interval 2, the current I of the current branch decreases to I-I with the increase of the voltage and the decrease of the currents3When (i) point a in fig. 6, the bypass diode D3Turning off, and recovering the 3 rd photovoltaic cell to work; as the voltage of the photovoltaic array continues to increase and the current continues to decrease, i.e. to point b in fig. 6, the bypass diode D now passes4Also turned off, present branchCurrent I is reduced to I ═ Is4And when the battery string is started, all the batteries of the battery string are recovered to a normal working state.
The specific fault diagnosis process of the method is described in detail by taking the embodiment of the invention as the center. The described embodiments of the fault diagnosis process or certain features should be understood that the present description is only intended to describe the present invention with respect to the photovoltaic array model given as an example, and in fact, certain details may be changed for the fault diagnosis of photovoltaic arrays of different configurations, and such changes are intended to fall within the scope of the present invention.
Example two:
the photovoltaic array fault and defect diagnosis system can realize a photovoltaic array fault and defect diagnosis method in the first embodiment, and comprises the following steps:
an acquisition module: the photovoltaic array is used for collecting the voltage and current values of each photovoltaic cell string in the photovoltaic array;
a positioning module: the battery string is used for comparing the acquired voltage values and finding out the battery string with the minimum voltage value and the current and voltage values of the battery string;
a primary judgment module: the device is used for calculating the difference value between the voltage value of the battery string with the minimum voltage value and the voltage value under normal operation and judging whether the difference value exceeds the normal deviation;
a reacquisition module: the voltage and current values of each photovoltaic cell string in the photovoltaic array are collected again to continue monitoring when the difference value does not exceed the normal deviation;
a secondary judgment module: the battery string judging module is used for placing the battery string with the minimum voltage value into a suspected fault group to judge a secondary fault battery string when the difference exceeds the normal deviation;
a positioning calculation module: the photovoltaic array parameter estimation model is used for collecting the temperature and the light intensity of the photovoltaic cell when the secondary fault cell string is judged and determined, positioning the fault cell and calculating the resistance estimation value of the photovoltaic cell in combination with the photovoltaic array parameter estimation model;
a fault type judging module: and the photovoltaic cell resistance evaluation value is used for comparing the photovoltaic cell resistance evaluation value with a normal value and judging the fault type of the photovoltaic cell resistance evaluation value.
Example three:
the embodiment of the invention also provides a photovoltaic array fault and defect diagnosis device, which can realize the photovoltaic array fault and defect diagnosis method in the first embodiment and comprises a processor and a storage medium;
the storage medium is to store instructions;
the processor is configured to operate in accordance with the instructions to perform the steps of the method of:
collecting the voltage and current values of each photovoltaic cell string in the photovoltaic array;
comparing the collected voltage values, and finding out the battery string with the minimum voltage value and the current voltage value of the battery string;
calculating the difference value between the voltage value of the battery string with the minimum voltage value and the voltage value under normal operation, and judging whether the difference value exceeds the normal deviation;
when the difference value does not exceed the normal deviation, the voltage and current values of all the photovoltaic cell strings in the photovoltaic array are collected again to continue monitoring;
when the difference exceeds the normal deviation, putting the battery string with the minimum voltage value into a suspected fault group to judge the secondary fault battery string;
when the secondary fault battery string is judged and determined, acquiring the temperature and the light intensity of the photovoltaic battery, positioning the fault battery and calculating the resistance estimation value of the photovoltaic battery by combining a photovoltaic array parameter estimation model;
calculating a photovoltaic cell resistance estimated value based on the current voltage value of the fault cell string;
and comparing the estimated value of the resistance of the photovoltaic cell with a normal value, and judging the fault type of the photovoltaic cell.
Example four:
an embodiment of the present invention further provides a computer-readable storage medium, which can implement the method for diagnosing a fault and a defect in a photovoltaic array in the first embodiment, where a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the method includes the following steps:
collecting the voltage and current values of each photovoltaic cell string in the photovoltaic array;
comparing the acquired voltage values, and finding out the battery string with the minimum voltage value and the current and voltage values of the battery string;
calculating the difference value between the voltage value of the battery string with the minimum voltage value and the voltage value under normal operation, and judging whether the difference value exceeds the normal deviation;
when the difference value does not exceed the normal deviation, the voltage and current values of all the photovoltaic cell strings in the photovoltaic array are collected again to continue monitoring;
when the difference exceeds the normal deviation, putting the battery string with the minimum voltage value into a suspected fault group to judge the secondary fault battery string;
when the secondary fault battery string is judged and determined, acquiring the temperature and the light intensity of the photovoltaic battery, positioning the fault battery and calculating the resistance estimation value of the photovoltaic battery by combining a photovoltaic array parameter estimation model;
calculating a photovoltaic cell resistance estimated value based on the current voltage value of the fault cell string;
and comparing the estimated value of the resistance of the photovoltaic cell with a normal value, and judging the fault type of the photovoltaic cell.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A method for diagnosing a fault defect of a photovoltaic array is characterized by comprising the following steps:
collecting the voltage and current values of each photovoltaic cell string in the photovoltaic array;
comparing the collected voltage values, and finding out the battery string with the minimum voltage value and the current voltage value of the battery string;
calculating the difference value between the voltage value of the battery string with the minimum voltage value and the voltage value under normal operation, and judging whether the difference value exceeds the normal deviation;
when the difference value does not exceed the normal deviation, the voltage and current values of all the photovoltaic cell strings in the photovoltaic array are collected again to continue monitoring;
when the difference value exceeds the normal deviation, putting the battery string with the minimum voltage value into a suspected fault group to judge a secondary fault battery string;
when the secondary fault battery string is judged and determined, acquiring the temperature and the light intensity of the photovoltaic battery, positioning the fault battery and calculating the resistance estimation value of the photovoltaic battery by combining a photovoltaic array parameter estimation model;
calculating a photovoltaic cell resistance estimated value based on the current voltage value of the fault cell string;
and comparing the estimated value of the resistance of the photovoltaic cell with a normal value, and judging the fault type of the photovoltaic cell.
2. The method of claim 1, wherein the method further comprises,
when the difference exceeds the normal deviation, the battery string with the minimum voltage value is placed into a suspected fault group for secondary fault battery string judgment, and the method comprises the following steps:
continuously collecting the voltage and the current values of the photovoltaic cells in the suspected fault group for three times, wherein the time interval of each collection is two hours;
calculating the difference value between the voltage value of the photovoltaic cell in the three suspected fault groups and the voltage value under normal operation;
when the photovoltaic cells in the suspected fault group do not continuously exceed the normal deviation for three times, the voltage and the current values of the photovoltaic cells in the suspected fault group are continuously collected for three times again for detection;
and when the photovoltaic cells in the suspected fault group continuously exceed the normal deviation for three times, determining the photovoltaic cells in the suspected fault group as a fault cell string.
3. The method of claim 1, wherein the photovoltaic cell resistance estimate is:
in the formula, Rs、RshAre estimated values of series and parallel resistances respectively, A is a curve fitting constant, UTIs a thermal voltage, ImIs the maximum current, IscFor short-circuit current, UocIs open circuit voltage, UmIs the maximum voltage.
4. The method of claim 3, wherein the maximum current, the short circuit current, the open circuit voltage and the maximum voltage are detected.
5. The method of claim 3, wherein the curve fitting constants are:
wherein A is a curve fitting constant, Uoc1、Isc1Open circuit voltage and short circuit current under ambient conditions, Uoc2、Isc2Open circuit voltage and short circuit current, U, under ambient conditions twoTIs a thermal voltage.
6. The method of claim 3, wherein the thermal voltage is:
in the formula of UTK is a boltzmann constant, T is a battery thermodynamic temperature, and q is an electron charge amount.
7. The method of claim 1, wherein the normal deviation is an artificial preset value.
8. A photovoltaic array fault defect diagnostic system, comprising:
an acquisition module: the photovoltaic array is used for collecting the voltage and current values of each photovoltaic cell string in the photovoltaic array;
a positioning module: the battery string is used for comparing the acquired voltage values and finding out the battery string with the minimum voltage value and the current voltage value of the battery string;
a primary judgment module: the device is used for calculating the difference value between the voltage value of the battery string with the minimum voltage value and the voltage value under normal operation and judging whether the difference value exceeds the normal deviation;
a reacquisition module: the voltage and current values of all the photovoltaic cell strings in the photovoltaic array are collected again to continue monitoring when the difference value does not exceed the normal deviation;
a secondary judgment module: the battery string judging module is used for placing the battery string with the minimum voltage value into a suspected fault group to judge a secondary fault battery string when the difference exceeds the normal deviation;
a positioning calculation module: the photovoltaic array parameter estimation model is used for collecting the temperature and the light intensity of the photovoltaic cell when the secondary fault cell string is judged and determined, positioning the fault cell and calculating the resistance estimation value of the photovoltaic cell in combination with the photovoltaic array parameter estimation model;
a fault type judgment module: and the photovoltaic cell resistance evaluation value is used for comparing the photovoltaic cell resistance evaluation value with a normal value and judging the fault type of the photovoltaic cell resistance evaluation value.
9. The photovoltaic array fault defect diagnosis device is characterized by comprising a processor and a storage medium;
the storage medium is used for storing instructions;
the processor is configured to operate in accordance with the instructions to perform the steps of the method according to any one of claims 1 to 7.
10. Computer readable storage medium, on which a computer program is stored, characterized in that the program, when being executed by a processor, is adapted to carry out the steps of the method of any one of claims 1 to 7.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116366004A (en) * | 2023-05-30 | 2023-06-30 | 国家电投集团云南国际电力投资有限公司 | Fault detection method, device and equipment of photovoltaic power generation system and storage medium |
| CN117498801A (en) * | 2023-12-29 | 2024-02-02 | 兰州理工大学 | Photovoltaic array shading fault diagnosis method based on KKPDC light transmittance detection |
| CN117761567A (en) * | 2024-02-22 | 2024-03-26 | 天津瑞芯源智能科技有限责任公司 | data analysis method for intelligent ammeter battery current test |
| CN117792276A (en) * | 2023-11-22 | 2024-03-29 | 华能太仓发电有限责任公司 | Positioning method of fault photovoltaic module of photovoltaic field |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116366004A (en) * | 2023-05-30 | 2023-06-30 | 国家电投集团云南国际电力投资有限公司 | Fault detection method, device and equipment of photovoltaic power generation system and storage medium |
| CN116366004B (en) * | 2023-05-30 | 2023-09-15 | 国家电投集团云南国际电力投资有限公司 | Fault detection method, device and equipment of photovoltaic power generation system and storage medium |
| CN117792276A (en) * | 2023-11-22 | 2024-03-29 | 华能太仓发电有限责任公司 | Positioning method of fault photovoltaic module of photovoltaic field |
| CN117498801A (en) * | 2023-12-29 | 2024-02-02 | 兰州理工大学 | Photovoltaic array shading fault diagnosis method based on KKPDC light transmittance detection |
| CN117498801B (en) * | 2023-12-29 | 2024-03-26 | 兰州理工大学 | Photovoltaic array shading fault diagnosis method based on KKPDC light transmittance detection |
| CN117761567A (en) * | 2024-02-22 | 2024-03-26 | 天津瑞芯源智能科技有限责任公司 | data analysis method for intelligent ammeter battery current test |
| CN117761567B (en) * | 2024-02-22 | 2024-04-26 | 天津瑞芯源智能科技有限责任公司 | Data analysis method for intelligent ammeter battery current test |
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