CN112329239B - Photovoltaic module series branch output characteristic curve modeling method under variable working conditions - Google Patents
Photovoltaic module series branch output characteristic curve modeling method under variable working conditions Download PDFInfo
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Abstract
The invention discloses a modeling method for an output characteristic curve of a photovoltaic module series branch under a variable working condition, and provides a detailed modeling method for the output characteristic curve of the photovoltaic module series branch, which is simple in calculation and high in precision, aiming at the condition that the working conditions such as irradiance and temperature are inconsistent. The method solves a small number of parameters of the photovoltaic module when the working condition changes by using a simple algebraic method, provides a method for approximating the output characteristic curve of the photovoltaic module under the non-standard working condition by using a Bezier curve, performs interval division based on Bezier calculation results, and gives the step of modeling the output characteristic curve of the series photovoltaic branch in different intervals in detail, thereby not only improving the modeling precision of the output characteristic curve of the series photovoltaic branch under the condition of inconsistent working conditions, but also effectively reducing the complexity and difficulty of engineering application.
Description
Technical Field
The invention belongs to a photovoltaic module output characteristic curve modeling method, and particularly relates to a photovoltaic module series branch output characteristic curve modeling method under a variable working condition.
Background
A series branch of a plurality of photovoltaic modules (with bypass diodes) is the basic topology of photovoltaic power generation. Under the influence of factors such as shadows generated by clouds, mountains and buildings, working conditions such as irradiance and temperature of each photovoltaic module forming the same series branch have larger difference, so that a plurality of steps exist in an output characteristic curve of the whole branch, whether the output characteristic curve of the photovoltaic module series branch under the non-uniform working condition can be simply and accurately constructed is not only directly related to the precision of maximum power point tracking, but also the accuracy of economic benefit evaluation is influenced, and the method has great significance for improving the efficiency of solar power generation and the early planning of a photovoltaic power station.
At present, the following 2 methods are mainly used for modeling the output characteristic curve of a photovoltaic module (with a bypass diode) series branch under the condition of inconsistent working conditions: 1. modeling each photovoltaic module by using a simplified engineering model, and further providing an output characteristic curve of the whole series branch; 2. and calculating parameters related to the transcendental equation of each photovoltaic module based on the diode model, and substituting parameter results into the transcendental equation for solving to obtain an output characteristic curve of the whole series branch. However, the method has the following disadvantages that the modeling precision of the simplified engineering model adopted by the method 1 is not high, and a large error exists; the method 2 needs to solve the parameters contained in the transcendental equation numerically, and the calculation process is complicated. In addition, the details of modeling of the photovoltaic module series branch under the condition of inconsistent working conditions are not given in the 2 methods, and particularly, the description of the process of jumping of the characteristic curve between the adjacent 2 steps is not detailed enough, so that the mastering difficulty of a user on the technology is improved, and the application of engineering practice is not facilitated.
Disclosure of Invention
Aiming at the defects in the prior art, the modeling method for the output characteristic curve of the series branch under the changing working condition solves the problems of large error, low precision and complex modeling process of the existing modeling method for the output characteristic curve.
In order to achieve the purpose of the invention, the invention adopts the technical scheme that: a photovoltaic module series branch output characteristic curve modeling method under a variable working condition comprises the following steps:
s1, calculating and testing parameters of the photovoltaic modules on the serial branches;
s2, calculating key point data of each photovoltaic module under different working conditions based on each photovoltaic module parameter;
s3, determining Bezier output characteristic curves of the photovoltaic modules under different working conditions based on the Bezier function by using the key point data of the photovoltaic modules;
s4, classifying the photovoltaic modules under the same working condition based on the Bezier output characteristic curves of the photovoltaic modules, and determining corresponding output characteristic curves;
s5, carrying out interval division on the output current and voltage of the photovoltaic modules under various same working conditions based on the output characteristic curve;
and S6, according to the interval division results of the output current and the voltage of the photovoltaic modules under various same working conditions, drawing an output characteristic curve of the series branch under the changing working conditions.
Further, the photovoltaic module parameters in step S1 include the actual irradiance G of each photovoltaic module during operationbAnd the actual junction temperature TbMaximum power point voltage V under standard working condition of each photovoltaic modulemOpen circuit voltage VocMaximum power point current ImShort-circuit current IscIdeality factor A of each photovoltaic module diode and thermal voltage V of each photovoltaic modulet；
The ideal factor A of the diode of the photovoltaic module is as follows:
in the formula, VmIs the maximum power point voltage, V, under the standard working conditionocIs open circuit voltage under standard working condition, ImIs the maximum power point current under the standard working condition, IscShort-circuit current under standard working condition;
thermal voltage V of photovoltaic moduletComprises the following steps:
in the formula, K is Boltzmann constant, and q is an electronic quantity.
Further, the key point data in step S2 includes a maximum power point voltage V of the output characteristic curve of the photovoltaic module under a varying conditionmbMaximum power point current ImbShort-circuit current IscbOpen circuit voltage VocbAnd fill factor FF of each photovoltaic module at actual irradiance and temperature;
wherein, the maximum power point voltage V under the variation working conditionmbComprises the following steps:
Vmb＝Vm-β*ΔT
in the formula, Δ T is the difference between the temperature under the standard working condition and the actual junction temperature, and Δ T is T-TbT is the temperature under the standard working condition, and beta is the voltage temperature coefficient;
maximum power point current I under variable working conditionsmbComprises the following steps:
Imb＝Im*Gb/G
wherein G is irradiance under standard working condition, GbThe irradiance test value of the photovoltaic module in actual working is obtained;
short-circuit current I under variable working conditionsscbComprises the following steps:
Iscb＝Isc*Gb/G-αIsc*ΔT
wherein, the temperature coefficient of alpha current;
open-circuit voltage V under variable working conditionsocbComprises the following steps:
Vocb＝Voc-β*ΔT+Vt*log(Gb/G)
the fill factor FF is:
further, the Bezier output characteristic curves of the step S3 include a first Bezier output characteristic curve and a second Bezier output characteristic curve;
the step S3 specifically includes:
s31, determining the coordinate (V) of the position of the control point of the first 2 nd-order Bezier function on the straight line which is parallel to the parallel line of the connecting line of the open-circuit voltage and the short-circuit current and passes through the maximum power pointc,Ic)；
Vc＝Vmb-y1Vocb
Ic＝Imb+y1Iscb
In the formula (I), the compound is shown in the specification,y1is the length ratio of the first 2 nd order Bezier function, and y1＝-k1FF+b1，k1Is a first scale factor, b1Is a first offset;
s32 coordinates (V) of control point position based on first 2 nd order Bezier functionc,Ic) Calculating a first Bezier output characteristic curve;
s33, step S1, determine the coordinates (V) of the control point position of the second 2 nd order Bezier functiond,Id)；
Vd＝y2Vocb+Vmb
Id＝Imb-y2Iscb
In the formula, y2Is the length ratio of the first 2 nd order Bezier function, and y2＝-k2FF+b2，k2Is a second proportionality coefficient, b2Is a second offset;
s34 coordinates (V) of control point position based on second 2 nd order Bezier functiond,Id) And calculating a second Bezier output characteristic curve.
Further, the step S4 is specifically:
s41, arranging the abscissa of the first 2-order Bezier output characteristic curve and the second Bezier output characteristic curve from small to large to obtain a sequence HD 1;
s42, arranging the ordinate of the first 2-order Bezier output characteristic curve and the ordinate of the second Bezier output characteristic curve in a descending order to obtain a number sequence ZD 1;
s43, multiplying each value in the series HD1 by the number of the photovoltaic modules under the same working condition in the series branch to obtain a series M HD 1;
s44, taking the value in the M HD1 series as an abscissa and the value in the ZD1 series as an ordinate, and drawing an output characteristic curve of the photovoltaic module under the current working condition;
s45, repeating the steps S42-S44 to obtain output characteristic curves corresponding to the photovoltaic modules under K working conditions;
the same working condition is that the short-circuit current, the open-circuit voltage and the maximum power point voltage and current are equal.
Further, the step S5 is specifically:
s51 short-circuit current I of photovoltaic module under K working conditionsscbSorting according to the sequence from big to small;
s52 short-circuit current sequencing result I of photovoltaic modules based on K working conditionsscb,1,Iscb,2,....,Iscb,k,...,Iscb,KDividing the output current and the output voltage of the output characteristic curve corresponding to the photovoltaic module under each working condition into intervals;
and the subscript K is the serial number of the working condition type, and K is the total number of the working condition types of the photovoltaic module.
Further, the step S52 is specifically:
a1, in the output characteristic curve of the photovoltaic module with the working condition serial number k, taking the short-circuit current corresponding to the photovoltaic module of the current working condition as an initial value and taking the current value as 0 as an end value, and sequentially adding Iscb,k,...,Iscb,KThe output current between two adjacent current values in 0 is divided into an interval;
a2, defining the sequence of the output current data of the interval as I in each division intervalkiThe output voltage V of the intervalk(i-1)≥V>VkiA sequence of output voltage data within a range is defined as V'ki；
Wherein, subscript i is a marked interval number, and when i is 1, V isk(i-1)＝0；
A3, repeating the steps A1-A2, and realizing the interval division of the output current and the voltage of the output characteristic curve corresponding to the photovoltaic module under each working condition.
Further, the step S6 is specifically:
s61 maximum short-circuit current I of photovoltaic modulescb,1As a starting point, the current value is 0 as an end point, and the photovoltaic modules of which the output currents are between two adjacent current values are divided into one output characteristic curve branch in sequence;
s62, for each output characteristic curveLine branching, output current data I when photovoltaic module corresponding to minimum short-circuit current works alonekiAs an ordinate, the output current data I of each of the output characteristic curve brancheskiEach corresponding photovoltaic module outputs voltage data V'kiTaking the sum as an abscissa, and drawing a branch of the current output characteristic curve;
and S63, repeating the step S62, fitting all the drawn branches of the output characteristic curve, and drawing the output characteristic curve of the series branch under the changing working condition.
The invention has the beneficial effects that:
1. the calculation is simple and accurate: the current and voltage sequence of the photovoltaic module output characteristic curve under the changing working condition can be given only by solving the open-circuit voltage, the short-circuit current, the maximum power point voltage and current and the ideal factor of the diode under different working conditions through a simple algebraic equation and combining simple calculation of a BEZIER curve;
2. the principle is simple and clear: by utilizing a method for sequencing the short-circuit current values of different photovoltaic modules, a region division rule of the whole series branch is given, and voltage sequences corresponding to current sequences in different regions in the output characteristics can be directly obtained by combining the volt-ampere characteristics of the series circuit;
3. the details are detailed: through simple mathematical operations such as sequencing of data sequences, interval division, algebraic addition and the like, a detailed process for constructing a complete output characteristic curve of a series branch is provided, and derivation and verification of the whole curve in different step jumping processes can be realized by utilizing algebraic summation of the sequences;
4. the method is simple and easy to understand: the detailed process of generating the current and the corresponding voltage sequence in different intervals of the series branch is given, and the output characteristic curve can be analyzed by non-electrical professional engineering technicians by using basic physical knowledge, so that the series branch is easy to understand and apply by non-electrical professional users.
Drawings
Fig. 1 is a modeling method of an output characteristic curve of a photovoltaic module series branch under a changing working condition provided by the invention.
Fig. 2 is a schematic diagram of a series branch formed by photovoltaic modules under different working conditions.
Fig. 3 is a schematic diagram of a first current interval division of a certain photovoltaic module provided by the present invention.
Fig. 4 is a schematic diagram of a second current interval division of a certain photovoltaic module provided by the present invention.
Fig. 5 is a schematic diagram of current interval division of the series branch formed by the photovoltaic modules under different working conditions.
Fig. 6 is a schematic diagram of output characteristic curves of series branches formed by photovoltaic modules under different working conditions.
FIG. 7 is a schematic diagram of modeling results of two different photovoltaic modes under any working condition provided by the invention.
Detailed Description
The following description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention as defined and defined in the appended claims, and all matters produced by the invention using the inventive concept are protected.
As shown in fig. 1: a photovoltaic module series branch output characteristic curve modeling method under a variable working condition comprises the following steps:
s1, calculating and testing parameters of the photovoltaic modules on the serial branches;
s2, calculating key point data of each photovoltaic module under different working conditions based on each photovoltaic module parameter;
s3, determining Bezier output characteristic curves of the photovoltaic modules under different working conditions based on the Bezier function by using the key point data of the photovoltaic modules;
s4, classifying the photovoltaic modules under the same working condition based on the Bezier output characteristic curves of the photovoltaic modules, and determining corresponding output characteristic curves;
s5, carrying out interval division on the output current and voltage of the photovoltaic modules under various same working conditions based on the output characteristic curve;
and S6, according to the interval division results of the output current and the voltage of the photovoltaic modules under various same working conditions, drawing an output characteristic curve of the series branch under the changing working conditions.
The photovoltaic module parameters in step S1 of this embodiment include the number m of photovoltaic modules, and the actual irradiance G of each photovoltaic module during operationbAnd the actual junction temperature TbMaximum power point voltage V under standard working condition of each photovoltaic modulemOpen circuit voltage VocMaximum power point current ImShort-circuit current IscIdeality factor A of each photovoltaic module diode and thermal voltage V of each photovoltaic modulet(ii) a Actual irradiance G of each photovoltaic module during workingbAnd the actual junction temperature TbThe maximum power point voltage V is obtained by testingmOpen circuit voltage VocMaximum power point current ImAnd short-circuit current IscPhotovoltaic module parameters given by a manufacturer data manual;
the ideal factor A of the diode of the photovoltaic module is as follows:
thermal voltage V of photovoltaic moduletComprises the following steps:
in the formula, K is Boltzmann constant, and q is an electron electric quantity.
In step S2 of this embodiment, when calculating the key point data of the photovoltaic modules under different operating conditions (irradiance and temperature), taking the S1 branch in fig. 2 as an example, the key point data of 4 types of photovoltaic modules a1 (K), B1 (L), C1 (N) and D1 (M) in the S1 branch is calculated, including the maximum power point voltage V of the output characteristic curve of the photovoltaic module under the changing operating conditionmbMaximum power point current ImbShort-circuit current IscbOpen circuit voltage VocbAnd fill factor FF of each photovoltaic module at actual irradiance and temperature;
wherein, the maximum power point voltage V under the variable working conditionmbComprises the following steps:
Vmb＝Vm-β*ΔT
in the formula, Δ T is the difference between the temperature under the standard working condition and the actual junction temperature, and Δ T is T-TbT is the temperature under the standard working condition, and beta is the voltage temperature coefficient;
maximum power point current I under variable working conditionsmbComprises the following steps:
Imb＝Im*Gb/G
wherein G is irradiance under standard working condition, GbThe irradiance test value of the photovoltaic module in actual working is obtained;
short-circuit current I under variable working conditionsscbComprises the following steps:
Iscb＝Isc*Gb/G-αIsc*ΔT
wherein, the temperature coefficient of alpha current;
open-circuit voltage V under variable working conditionsocbComprises the following steps:
Vocb＝Voc-β*ΔT+Vt*log(Gb/G)
the fill factor FF is:
the Bezier output characteristic curves in step S3 of the present embodiment include a first Bezier output characteristic curve and a second Bezier output characteristic curve; step S3 specifically includes:
s31, determining the coordinate (V) of the position of the control point of the first 2 nd-order Bezier function on the straight line which is parallel to the parallel line of the connecting line of the open-circuit voltage and the short-circuit current and passes through the maximum power pointc,Ic)；
Vc＝Vmb-y1Vocb
Ic＝Imb+y1Iscb
In the formula, y1Is the length ratio of the first 2 nd order Bezier function, and y1＝-k1FF+b1，k1Is a first scale factor, b1Is a first offset;
s32 coordinates (V) of control point position based on first 2 nd order Bezier functionc,Ic) Calculating a first Bezier output characteristic curve;
s33, step S1, determine the coordinates (V) of the control point position of the second 2 nd order Bezier functiond,Id)；
Vd＝y2Vocb+Vmb
Id＝Imb-y2Iscb
In the formula, y2Is the length ratio of the first 2 nd order Bezier function, and y2＝-k2FF+b2，k2Is a second proportionality coefficient, b2Is a second offset;
s34 coordinates (V) of control point position based on second 2 nd order Bezier functiond,Id) And calculating a second Bezier output characteristic curve.
It should be noted that the specific construction method of the two Bezier output characteristic curves is clearly described in the patent with the application number of 202010940983.2, and is not repeated herein.
Step S4 of this embodiment specifically includes:
s41, arranging the abscissa of the first 2-order Bezier output characteristic curve and the abscissa of the second Bezier output characteristic curve in a descending order to obtain a sequence HD 1;
s42, arranging the ordinate of the first 2-order Bezier output characteristic curve and the ordinate of the second Bezier output characteristic curve in a descending order to obtain a number sequence ZD 1;
s43, multiplying each value in the series HD1 by the number of the photovoltaic modules under the same working condition in the series branch to obtain a series M HD 1;
s44, taking the value in the M HD1 series as an abscissa and the value in the ZD1 series as an ordinate, and drawing an output characteristic curve of the photovoltaic module under the current working condition;
s45, repeating the steps S42-S45 to obtain output characteristic curves corresponding to the photovoltaic modules under K working conditions;
the same working condition is that the short-circuit current, the open-circuit voltage and the maximum power point voltage and current are equal.
Step S5 of this embodiment specifically includes:
s51 short-circuit current I of photovoltaic module under K working conditionsscbSorting according to the sequence from big to small;
s52 short-circuit current sequencing result I of photovoltaic modules based on K working conditionsscb,1,Iscb,2,....,Iscb,k,...,Iscb,KDividing the output current and the output voltage of the output characteristic curve corresponding to the photovoltaic module under each working condition into intervals;
and the subscript K is the serial number of the working condition type, and K is the total number of the working condition types of the photovoltaic module.
In the embodiment, the selection of sorting the short-circuit current is the simplest and most clear sorting method, a section division rule of the whole circuit is given based on a sorting result of the short-circuit current, a volt-ampere characteristic of a series circuit is given, and voltage sequences corresponding to current sequences in different sections in the output characteristic can be directly obtained.
The step S52 is specifically:
a1, in the output characteristic curve of the photovoltaic module with the working condition serial number k, taking the short-circuit current corresponding to the photovoltaic module of the current working condition as an initial value and taking the current value as 0 as an end value, and sequentially adding Iscb,k,...,Iscb,KThe output current between two adjacent current values in 0 is divided into an interval;
a2, defining the sequence of the output current data of the interval as I in each division intervalkiThe output voltage V of the intervalk(i-1)≥V>VkiThe sequence of the output voltage data within is defined as V'ki；
Wherein, subscript i is a marked interval number, and when i is 1, V isk(i-1)＝0；
A3, repeating the steps A1-A2, and realizing the interval division of the output current and the voltage of the output characteristic curve corresponding to the photovoltaic module under each working condition.
Wherein for each of the partitioned output voltage ranges Vk(i-1)≥V>VkiBased on the result of dividing the current intervals, each current interval theoretically corresponds to a voltage interval, i.e. the voltage and current data (i.e. the sequence) are in one-to-one correspondence, so that V is the ratio of the voltage to the currentkiMay be understood as corresponding to the minimum current value in the corresponding current interval (i.e. current sequence);
the steps in the embodiment are based on volt-ampere characteristics, the current of the whole circuit in the series circuit is equal, therefore, interval division is carried out according to the current, and then the voltage value corresponding to each current interval is searched;
for example, the method for performing interval division based on the photovoltaic module series branch in fig. 2 specifically includes:
(1) obtaining the open-circuit voltage V of K A1 photovoltaic modules according to the calculation stepsocb,1Short-circuit current of Iscb,1The open-circuit voltage of L B1 photovoltaic modules is Vocb,2Short circuit current of Iscb,2The open-circuit voltage of L B1 photovoltaic modules is Vocb,3Short-circuit current of Iscb,3The open circuit voltage of M D1 photovoltaic modules is Vocb,4Short-circuit current of Iscb,4(ii) a According to the magnitude of short-circuit currentscb,1、Iscb,2、Iscb,3And Iscb,4Sorting is carried out;
(2) according to the sequencing result of the short-circuit current, the current in the output characteristic curve of the K A1 photovoltaic modules is divided into the following intervals:
①Iscb,1≥I>Iscb,2a section, the sequence of the output current data of the section is defined as I11The output voltage in the interval is 0 to V>V11The sequence of the voltage data is defined as V'11；
②Iscb,2≥I>Iscb,3A section, the sequence of the output current data of the section is defined as I12The output voltage of the interval is V11≥V>V12The sequence of the voltage data is defined as V'12；
The results between the two divisions are shown in FIG. 3;
③Iscb,3≥I>Iscb,4a section, the sequence of the output current data of the section is defined as I13The output voltage of the interval is V12≥V>V13The sequence of the voltage data is defined as V'13；
④Iscb,4The interval of more than or equal to I and more than or equal to 0, and the sequence of the output current data in the interval is defined as I13The output voltage of the interval is V13≥V>V14The sequence of the voltage data is defined as V'14；
The two interval division results are shown in fig. 4;
the current of the output characteristic curve of the L B1 photovoltaic modules is divided into the following intervals:
①Iscb,2≥I>Iscb,3a section, the sequence of the output current data of the section is defined as I21The output voltage in the interval is 0 to V>V21The sequence of the voltage data is defined as V'21；
②Iscb,3≥I>Iscb,4A section, the sequence of the output current data of the section is defined as I22The output voltage of the interval is V21≥V>V22The sequence of the voltage data is defined as V'22；
③Iscb,4The interval of more than or equal to I and more than or equal to 0, and the sequence of the output current data in the interval is defined as I23The output voltage of the interval is V22≥V>V23The sequence of the voltage data is defined as V'23；
The current of the output characteristic curves of the N C1 photovoltaic modules is divided into the following intervals:
①Iscb,3≥I>Iscb,4an interval, a sequence of the output current data of the interval is defined as I31The output voltage in the interval is 0 to V>V31The sequence of the voltage data is defined as V'31；
②Iscb,4The interval of more than or equal to I and more than or equal to 0, and the sequence of the output current data in the interval is defined as I32The output voltage of the interval is V31≥V>V32The sequence of the voltage data is defined as V'32；
The current of the output characteristic curves of the M D1 photovoltaic modules is divided into the following intervals:
①Iscb,4the interval of more than or equal to I and more than or equal to 0, and the sequence of the output current data in the interval is defined as I41The output voltage in the interval is 0 to V>V41The sequence of the voltage data is defined as V'41；
Based on the interval division method, the interval division result of the whole S1 branch in fig. 2 is shown in fig. 5;
step S6 of this embodiment specifically includes:
s61, maximum short-circuit current I of photovoltaic modulescb,1As a starting point, the current value is 0 as an end point, and the photovoltaic modules of which the output currents are between two adjacent current values are divided into one output characteristic curve branch in sequence;
s62, for each output characteristic curve branch, outputting current data I when the photovoltaic module corresponding to the minimum short-circuit current works independentlykiAs an ordinate, the output current data I of each of the output characteristic curve brancheskiCorresponding photovoltaic module output voltage data V'kiTaking the sum as an abscissa, and drawing a branch of the current output characteristic curve;
and S63, repeating the step S62, fitting all the drawn branches of the output characteristic curve, and drawing the output characteristic curve of the series branch under the changing working condition.
Specifically, based on the interval division result shown in fig. 5, an output characteristic curve of the series branch S1 under the changed working condition is constructed:
(1) in Iscb,1≥I>Iscb,2In the interval, the ordinate of the output characteristic curve of the S1 branch is current, the abscissa is voltage, wherein the ordinate is that K A1 photovoltaic modules work independently at Iscb,1≥I>Iscb,2Interval current I11The abscissa voltage is the output voltage V 'of the K A1 photovoltaic modules in independent operation'11；
(2) In Iscb,1≥I>Iscb,2In the interval, the ordinate of the output characteristic curve of the S1 branch circuit is current, the abscissa is voltage, and due to the fact that two current curves exist in the current interval, the K A1 photovoltaic modules work independently at Iscb,1≥I>Iscb,2Interval current I12And L B1 photovoltaic modules operating independently at Iscb,1≥I>Iscb,2Interval current I21；
Thus, the ordinate of the partial curve is selected such that the L B1 photovoltaic modules operate individually at Iscb,1≥I>Iscb,2Current data sequence I of intervals21The abscissa is I21The sum of data points of the two voltage sequences corresponding to each current, the two voltages to be summed are respectively the output voltage sequence V 'of the L photovoltaic modules B1 working independently'21And K output voltage data sequences V 'of A1 photovoltaic modules'12；
For example, the current data sequence contains data points I12＝[I121,I122…,I12i…I12q]，I21＝[I211,I212…,I21j…,I21p]The voltage sequence contains V 'to the data point'12＝[V121,V122…,V12i,…V12q]，V'21＝[V211,V212…,V21j…,V21p]Wherein, I12i＝I21jThen the current output at that point is I21j，I21jThe corresponding voltage value is V12i+V21j；
(3) In Iscb,3≥I>Iscb,4In the interval, the ordinate of the output characteristic curve of the branch S1 is current, and the abscissa is voltageThree current curves exist in the current interval, and the K A1 modules respectively work at I independentlyscb,3≥I>Iscb,4Interval current I31L B1 photovoltaic modules independently work at Iscb,3≥I>Iscb,4Interval I22And N C1 photovoltaic modules operating independently at Iscb,3≥I>Iscb,4Interval I31；
Thus, the ordinate of the partial curve is selected to be N C1 photovoltaic modules operating at I alonescb,3≥I>Iscb,4Current data sequence I of intervals31The abscissa is I31The sum of data points of the three voltage sequences corresponding to each current, the three voltage sequences to be summed are respectively the output voltage sequences V 'of the N photovoltaic modules C1 which work independently'31L photovoltaic modules B1 operated individually are output voltage sequences V'22And K output voltage data sequences V 'of A1 photovoltaic modules'13；
For example, the current data sequence contains data points I13＝[I131,I132…,I13i…I13q]，I22＝[I221,I222…,I22j…,I22p]，I31＝[I311,I312…,I31t…I31y]The voltage sequence contains V 'to the data point'13＝[V131,V132…,V13i,…V13o]，V'22＝[V221,V222…,V22j…,V22u]，V'31＝[V311,V312…,V31t…,V31y]Wherein, I13i＝I22j＝I31tThen the current output at that point is I31t，I31tThe corresponding voltage value is V13i+V22j+V31t；
(4) In Iscb,4The interval of more than or equal to I and more than or equal to 0, the ordinate of the output characteristic curve of the S1 branch circuit is current, the abscissa is voltage, and as four current curves exist in the current interval, the K A1 photovoltaic modules work independently at Iscb,4Current I in interval of I being more than or equal to 014L B1 photovoltaic modules operating independently at Iscb,4The current I is greater than or equal to I and greater than or equal to 022N number of C1 photovoltaic modules operating independently at Iscb,4The current I is greater than or equal to I and greater than or equal to 031M D1 photovoltaic modules operating independently at Iscb,4The current I is greater than or equal to I and greater than or equal to 041；
Thus, the ordinate of the partial curve is selected to be M D1 photovoltaic modules operating individually at Iscb,4Current data sequence I with interval of more than or equal to I and more than or equal to 041The abscissa is I41The sum of data points of the four voltage sequences corresponding to each current, four voltage sequences needing to be summed, and output voltage sequences V 'when the M photovoltaic modules D1 work independently'41N photovoltaic modules C1 are operated individually'32L output voltage sequences V when B1 photovoltaic modules work alone23And K A1 photovoltaic module output voltage sequences V'14；
For example, the current data sequence contains data points I14＝[I141,I142…,I14i…I14o]，I23＝[I231,I232…,I23j…,I23u]，I32＝[I321,I322…,I32t…I32y]，I41＝[I411,I412…,I41r…I41e]The voltage sequence contains data points of V'14＝[V141,V142…,V14i,…V13o]，V'23＝[V231,V232…,V23j…,V23u]，V'32＝[V321,V322…,V32t…,V32y]，V'41＝[V411,V412…,V41r…,V41e]Wherein, I14i＝I23j＝I32t＝I41rThen the current output at that point is I41r，I41rThe corresponding voltage value is V14i+V23j+V32t+V41r；
The output characteristic curve branches of the intervals are fitted to obtain an output characteristic curve of the photovoltaic module with the branch S1 as shown in fig. 6, and the output characteristic curve of the whole series branch is simply and clearly displayed in the graph, so that engineering technicians in non-electrical professions can analyze the output characteristic curve by using basic physical knowledge.
Example 2:
the modeling results of two different photovoltaic modules under any one disclosure are respectively given in fig. 7, and comparison of the contents in the graph shows that the solution of the photovoltaic module by using the key parameter calculation in combination with the Bezier function in the present invention has higher precision compared with the conventional modeling method.
Claims (4)
1. A photovoltaic module series branch output characteristic curve modeling method under a change working condition is characterized by comprising the following steps:
s1, calculating and testing parameters of the photovoltaic modules on the serial branches;
s2, calculating key point data of each photovoltaic module under different working conditions based on each photovoltaic module parameter;
s3, determining Bezier output characteristic curves of the photovoltaic modules under different working conditions based on the Bezier function by using the key point data of the photovoltaic modules;
s4, classifying the photovoltaic modules under the same working condition based on the Bezier output characteristic curves of the photovoltaic modules, and determining corresponding output characteristic curves;
s5, carrying out interval division on the output current and voltage of the photovoltaic modules under various same working conditions based on the output characteristic curve;
s6, according to the interval division results of the output current and the voltage of the photovoltaic modules under various same working conditions, drawing an output characteristic curve of the series branch under the changing working conditions;
the photovoltaic module parameters in step S1 include the actual irradiance G of each photovoltaic module during operationbAnd the actual junction temperature TbMaximum power point voltage V under standard working condition of each photovoltaic modulemOpen circuit voltage VocMaximum power point current ImShort-circuit current IscIdeality factor A of each photovoltaic module diode and eachThermal voltage V of photovoltaic modulet；
The ideal factor A of the diode of the photovoltaic module is as follows:
in the formula, VmIs the maximum power point voltage, V, under the standard working conditionocOpen circuit voltage under standard operating conditions, ImIs the maximum power point current under the standard working condition, IscShort-circuit current under standard working condition;
thermal voltage V of photovoltaic moduletComprises the following steps:
in the formula, K is Boltzmann constant, and q is electronic electricity; the key point data in step S2 includes a maximum power point voltage V of the output characteristic curve of the photovoltaic module under a varying conditionmbMaximum power point current ImbShort-circuit current IscbOpen circuit voltage VocbAnd fill factor FF of each photovoltaic module at actual irradiance and temperature;
wherein, the maximum power point voltage V under the variable working conditionmbComprises the following steps:
Vmb＝Vm-β*ΔT
in the formula, Δ T is the difference between the temperature under the standard working condition and the actual junction temperature, and Δ T is T-TbT is the temperature under the standard working condition, and beta is the voltage temperature coefficient;
maximum power point current I under variable working conditionsmbComprises the following steps:
Imb＝Im*Gb/G
wherein G is irradiance under standard working condition, GbThe irradiance test value of the photovoltaic module in actual working is obtained;
short-circuit current I under variable working conditionsscbComprises the following steps:
Iscb＝Isc*Gb/G-αIsc*ΔT
wherein, the temperature coefficient of alpha current;
open-circuit voltage V under variable working conditionsocbComprises the following steps:
Vocb＝Voc-β*ΔT+Vt*log(Gb/G)
the fill factor FF is:
the Bezier output characteristic curves in the step S3 include a first Bezier output characteristic curve and a second Bezier output characteristic curve;
the step S3 specifically includes:
s31, determining the coordinate (V) of the position of the control point of the first 2 nd-order Bezier function on the straight line which is parallel to the parallel line of the connecting line of the open-circuit voltage and the short-circuit current and passes through the maximum power pointc,Ic)；
Vc＝Vmb-y1Vocb
Ic＝Imb+y1Iscb
In the formula, y1Is the length ratio of the first 2 nd order Bezier function, and y1＝-k1FF+b1，k1Is a first scale factor, b1Is a first offset;
s32 coordinates (V) of control point position based on first 2 nd order Bezier functionc,Ic) Calculating a first Bezier output characteristic curve;
s33, step S1, determine the coordinates (V) of the control point position of the second 2 nd order Bezier functiond,Id)；
Vd＝y2Vocb+Vmb
Id＝Imb-y2Iscb
In the formula, y2Is the length ratio of the first 2 nd order Bezier function, and y2＝-k2FF+b2，k2Is a second proportionality coefficient, b2Is a second offset;
s34 coordinates (V) of control point position based on second 2 nd order Bezier functiond,Id) Calculating a second Bezier output characteristic curve;
the step S4 specifically includes:
s41, arranging the abscissa of the first 2-order Bezier output characteristic curve and the abscissa of the second Bezier output characteristic curve in a descending order to obtain a sequence HD 1;
s42, arranging the ordinate of the first 2-order Bezier output characteristic curve and the ordinate of the second Bezier output characteristic curve in a descending order to obtain a number sequence ZD 1;
s43, multiplying each value in the series HD1 by the number of the photovoltaic modules under the same working condition in the series branch to obtain a series M HD 1;
s44, taking the value in the M HD1 series as an abscissa and the value in the ZD1 series as an ordinate, and drawing an output characteristic curve of the photovoltaic module under the current working condition;
s45, repeating the steps S42-S44 to obtain output characteristic curves corresponding to the photovoltaic modules under K working conditions;
the same working condition is that the short-circuit current, the open-circuit voltage and the maximum power point voltage and current are equal.
2. The method for modeling the output characteristic curve of the photovoltaic module series branch under the varying conditions according to claim 1, wherein the step S5 specifically comprises:
s51 short-circuit current I of photovoltaic module under K working conditionsscbSorting according to the sequence from big to small;
s52 short-circuit current sequencing result I of photovoltaic modules based on K working conditionsscb,1,Iscb,2,....,Iscb,k,...,Iscb,KDividing the output current and the output voltage of the output characteristic curve corresponding to the photovoltaic module under each working condition into intervals;
and the subscript K is the serial number of the working condition type, and K is the total number of the working condition types of the photovoltaic module.
3. The method for modeling the output characteristic curve of the photovoltaic module series branch under the varying conditions according to claim 2, wherein the step S52 specifically comprises:
a1, in the output characteristic curve of the photovoltaic module with the working condition serial number k, taking the short-circuit current corresponding to the photovoltaic module of the current working condition as an initial value and taking the current value as 0 as an end value, and sequentially adding Iscb,k,...,Iscb,KThe output current between two adjacent current values in 0 is divided into an interval;
a2, defining the sequence of the output current data of the interval as I in each division intervalkiThe output voltage V of the intervalk(i-1)≥V>VkiA sequence of output voltage data within a range is defined as V'ki；
Wherein, subscript i is a marked interval number, and when i is 1, V isk(i-1)＝0；
And A3, repeating the steps A1-A2, and realizing interval division of the output current and the voltage of the output characteristic curve corresponding to the photovoltaic module under each working condition.
4. The method for modeling the output characteristic curve of the photovoltaic module series branch under the varying conditions according to claim 3, wherein the step S6 specifically comprises:
s61 maximum short-circuit current I of photovoltaic modulescb,1As a starting point, the current value is 0 as an end point, and the photovoltaic modules of which the output currents are between two adjacent current values are divided into one output characteristic curve branch in sequence;
s62, for each output characteristic curve branch, outputting current data I when the photovoltaic module corresponding to the minimum short-circuit current works independentlykiAs an ordinate, the output current data I of each of the output characteristic curve brancheskiCorresponding photovoltaic module output voltage data V'kiTaking the sum as an abscissa, and drawing a branch of the current output characteristic curve;
and S63, repeating the step S62, fitting all the drawn branches of the output characteristic curve, and drawing the output characteristic curve of the series branch under the changing working condition.
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| CN104462715A (en) * | 2014-12-24 | 2015-03-25 | 黑龙江科技大学 | Photovoltaic cell output characteristic modeling method based on Bezier function |
| CN108733126A (en) * | 2018-05-25 | 2018-11-02 | 黑龙江科技大学 | Based on the polynomial photovoltaic array maximum power tracking methods of Bezier |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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Non-Patent Citations (4)
| Title |
|---|
| 不同迭代算法求解光伏模块参数的收敛速度;师楠等;《电力科学与技术学报》;20200528;第35卷(第3期);55-60 * |
| 基于Bezier函数光伏阵列建模对比仿真研究;师楠等;《可再生能源》;20160520;第34卷(第5期);656-659 * |
| 基于Bezier函数的光伏电池建模;师楠等;《电网技术》;20150805;2195-2200 * |
| 基于简化模型的光伏组件最大功率跟踪仿真;张亢等;《安阳工学院学报》;20190320(第02期);22-24+69 * |
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