WO2020211370A1 - Maximum photovoltaic power estimation method for photovoltaic power generation system - Google Patents

Abstract

Provided is a maximum photovoltaic power estimation method for a photovoltaic power generation system. The method comprises: according to the Shockley diffusion theory, determining an ideal factor A1 of a first diode to be one and determining an ideal factor A2 of a second diode to be two; determining a first nonlinear equation set f₁ and a second nonlinear equation set f₂ according to determined A1 and A2; initializing the values of R_s and R_sh; according to the values of R_sand R_sh obtained by means of initialization and f₁ and f₂, determining an error of one parameter of R_s and R_sh; according to the determined error of the parameter of R_s and R_sh, determining an error of the other parameter of R_s and R_sh; determining whether the determined error of the other parameter of R_s and R_sh is less than a tolerance value; in response to the determination that the error of the other parameter of R_s and R_sh is less than the tolerance value, determining the values of R_s and R_sh under standard conditions; and according to the determined values of R_s and R_sh under the standard conditions, determining the maximum power P_mp of a photovoltaic power generation system under the current environmental conditions.

Description

Maximum power estimation method of photovoltaic power generation system

This application claims the priority of a Chinese patent application filed with the Chinese Patent Office with an application number of 201910299193.8 on April 15, 2019. The entire content of the application is incorporated into this application by reference.

Technical field

The present disclosure belongs to the technical field of photovoltaic power generation, and specifically relates to a method for estimating the maximum power of a photovoltaic power generation system.

Background technique

As an important renewable energy power generation technology, photovoltaic power generation occupies an important position in energy development. With the gradual increase in the proportion of photovoltaic power generation, the power grid has put forward higher and higher requirements for the controllability of photovoltaic power generation systems. The maximum power estimation of the photovoltaic power generation system is to obtain the maximum power that the photovoltaic can output through numerical calculation, so as to facilitate the power grid to issue dispatching commands and control, and prevent the photovoltaic power generation system from being disconnected from the grid due to excessive output power fluctuations causing excessive impact on the grid. Abandonment of light and threats to the stability of the power grid. The Maximum Photovoltaic Power Estimation (MPPE) of the photovoltaic power generation system requires modeling and analysis of photovoltaic cells and modules first. Among them, the photovoltaic single diode model (also called the five-parameter model) is highly accurate and more accurate. It is widely used because of its low calculation difficulty. However, the accuracy of the photovoltaic single-diode model will be greatly reduced in the case of low solar radiation and open circuit voltage. The photovoltaic double-diode model compensates the recombination loss by connecting another diode in parallel with the photovoltaic single-diode model, thereby improving the accuracy of modeling. However, the dual-diode model is a seven-parameter model, so seven parameters need to be solved. However, the photovoltaic output characteristic is a nonlinear transcendental equation, and there is a greater risk of iteration failure during the solution process. The traditional linear approximation method will cause more problems in low-radiation environments. Because of large errors, the prediction accuracy cannot be guaranteed, that is, it is difficult to ensure both the iterative convergence during the solution process and the accuracy of the solution.

Summary of the invention

The present disclosure provides a method for estimating the maximum power of a photovoltaic power generation system. The method includes the following steps:

According to the Shockley diffusion theory, the ideality factor A1 of the first diode is 1 and the ideality factor A2 of the second diode is 2 in the formula for determining the photovoltaic output current of the dual diode model of the photovoltaic cell;

According to the determined A1 and A2, determine the first nonlinear equation set f ₁ and the second nonlinear equation set f ₂ , where both f ₁ and f ₂ include series resistance R _s , parallel resistance R _sh , first two Five parameters: the reverse saturation current I _o1 of the diode, the reverse saturation current I _{o2 of the} second diode, and the photovoltaic module photo-generated current I _ph ;

Initialize the values of R _s and R _sh ;

Values R _s and R _sh initialization obtained, and f ₁ and f _2, and determining the error R _s R _sh in accordance with a parameter;

The error of the determined R _s and R _sh in a parameter, determining the error in the R _s and R _sh other parameters;

Judge whether the error of another parameter in the determined R _s and R _sh is less than the tolerance value;

In response to determining that the error of the other parameter of R _s and R _sh is less than the tolerance value, determine the values of R _s and R _sh under standard conditions;

Determine the value of I _o1 , the value of I _{o2 and} the value of I _ph under the standard conditions according to the determined values of R _s and R _sh under the standard conditions;

According to the value of R _s , R _sh , I _o1 , I _o2 , and I _ph under the standard conditions, determine the value of R _s , R _sh , and I _o1 under the current environmental conditions , I _o2 value and I _ph value;

According to the determined value of R _s , R _sh , I _o1 , I _o2 and I _ph under the current environmental conditions, determine the maximum power P _mp of the photovoltaic power generation system under the current environmental conditions .

The beneficial effects of this article are:

The method for estimating the maximum power of a photovoltaic power generation system based on a dual-diode model provided by the present disclosure establishes a dual-diode 7 parameter model of the photovoltaic cell, and uses open-circuit voltage and short-circuit current parameters to realize the conversion calculation of environmental parameters to standard conditions; control by using parameters The LM algorithm makes the algorithm segmentally show the characteristics of the gradient descent method and the Gauss-Newton method, and fully combines the advantages of the two methods; the parameter calculation of the photovoltaic double diode model based on the LM algorithm is less affected by the selection of the initial value of the iteration , And speed up the convergence speed and accuracy; the maximum power value is obtained based on the open circuit voltage approximation method, which saves an iteration process and improves the calculation speed.

Description of the drawings

Fig. 1 is a flowchart of a method for estimating the maximum power of a photovoltaic power generation system according to an embodiment;

2 is a flowchart of a method for estimating the maximum power of a photovoltaic power generation system according to another embodiment;

FIG. 3 is an equivalent circuit of a dual diode model provided by an embodiment.

detailed description

The Levenberg-Marquard (LM) algorithm combines the advantages of the Gauss-Newton method and the gradient descent method, and improves the shortcomings of the two to ensure the speed and accuracy of the iterative convergence .

Fig. 1 is a flowchart of a method for estimating the maximum power of a photovoltaic power generation system according to an embodiment. Referring to Fig. 1, the method for estimating the maximum power of a photovoltaic power generation system includes the following steps.

S101. According to the Shockley diffusion theory, determine that the ideality factor A1 of the first diode is 1 and the ideality factor A2 of the second diode in the expression formula of the photovoltaic output current of the dual diode model of the photovoltaic cell is 2.

S102. According to the determined A1 and A2, determine the first nonlinear equation set f ₁ and the second nonlinear equation set f ₂ , where both f ₁ and f ₂ include series resistance R _s , parallel resistance R _sh , and There are five parameters: a diode reverse saturation current I _o1 , a second diode reverse saturation current I _o2 and a photovoltaic module photo-generated current I _ph .

S103. Initialize the values of R _s and R _sh .

S104, according to the value R _s and R _sh initialization obtained, and f ₁ and f _2, determining the error in the R _s and R _sh one parameter.

S105, according to the determined error R _s and R _sh in a parameter, determining the error in the R _s and R _sh another parameter.

S106: Judge whether the error of another parameter among the determined R _s and R _sh is less than the tolerance value.

S107. In response to determining that the error of the other parameter of R _s and R _sh is less than the tolerance value, determine the values of R _s and R _sh under standard conditions.

S108: Determine the value of I _o1 , the value of I _{o2 and} the value of I _ph under the standard conditions according to the determined values of R _s and R _sh under the standard conditions.

S109. Determine the value of R _s , the value of R _sh , and the value of I _o1 under current environmental conditions according to the value of R _s , the value of R _sh , the value of I _o1 , the value of I _o2 , and the value of I _ph under the standard conditions. The value of, the value of I _{o2 and} the value of I _ph .

S110. Determine the maximum power of the photovoltaic power generation system under the current environmental conditions according to the determined value of R _s , R _sh , I _o1 , I _o2 , and I _ph under the current environmental conditions. P _mp .

FIG. 2 is a flowchart of a method for estimating the maximum power of a photovoltaic power generation system according to another embodiment, and FIG. 3 is an equivalent circuit of a dual diode model of a photovoltaic cell, as shown in FIG. 2 and FIG. 3.

The photovoltaic output current can be expressed by formula (1):

In formula (1), I _ph is the photovoltaic module photo-generated current; I _o1 is the reverse saturation current of the first diode D ₁ , I _o2 is the reverse saturation current of the second diode; I _d1 is the first diode The current of the tube D ₁ and I _d2 are the currents flowing through the second diode D ₂ ; I _Rsh is the current flowing through the parallel resistance; R _s is the series resistance, R _sh is the parallel resistance; V is the output voltage of the photovoltaic cell and I is the output current of the photovoltaic cell; A ₁ is the ideality factor of the first diode D ₁ , and A ₂ is the ideality factor of the second diode D ₂ ; N _s is the number of photovoltaic modules connected in series; V _t =kT/q, k is Boltzmann constant (1.308×10 ^-23 J/K); q is the electronic charge (1.602×10 ^-19 C); T is the ambient temperature.

In order to reduce the calculation time and complexity of calculating the nonlinear equation, according to the Shockley diffusion theory, A ₁ =1 and A ₂ ＝2 in formula (1) can be taken, and the simplified double diode model has seven unknown parameters {I _ph ,I _o1 ,I _o2 ,R _sh ,R _s ,A ₁ ,A ₂ } are simplified into five {I _ph ,I _o1 ,I _o2 ,R _sh ,R _s }. These five parameters can be calculated from the data sheet information provided by the photovoltaic module manufacturer. The three important parameters provided in the data sheet are that the IV curve of the photovoltaic model is constant over three points under standard conditions, as shown in Table 1 (only Considering the uniform lighting conditions) are the open circuit voltage (V _oc , 0), short circuit current (0, I _sc ) and the maximum power point voltage and current (V _mp , _Imp ). These five can be obtained by iterative solution. Parameters.

Table 1 PV module data sheet and demand solution parameters

In Table 1, k _i is the short-circuit current coefficient, k _v is the open-circuit voltage coefficient, N _s is the number of photovoltaic modules in series, and N _p is the number of photovoltaic modules in parallel. Substituting the above three points and A ₁ =1 and A ₂ =2 into formula (1), formulas (2)-(4) can be obtained:

In order to obtain the five parameters, more equations are needed. The output power at any point on the IV curve of the photovoltaic module can be expressed by equation (5), and the derivative of voltage to power at the point (V _mp ,I _mp ) is known For 0, formulas (6)-(8) can be obtained.

P=VI (5)

Taking the formula (1) to the voltage and substituting it into the formula (8) to obtain the formula (9)-(10):

The value of I _ph is expressed in formula (2), and it is substituted into formulas (3)-(4) to obtain formulas (11)-(12):

There are four parameters {I _o1 ,I _o2 ,R _sh ,R _s } in formulas (10)-(12). The value of R _sh can be represented by the derivative of PV VI curve voltage to current at the short-circuit current point, and substituted In formula (9), formulas (13)-(14) are obtained.

During actual operation, each parameter needs to be converted to the current environmental conditions. The short-circuit current and open-circuit voltage have a linear relationship with temperature, as shown in equations (15) and (16), the subscripts with "STC" in the equations all indicate the parameter values under standard conditions, k _i is the temperature coefficient of short-circuit current, k _v is the open-circuit voltage temperature coefficient. The values of these two parameters under standard conditions are provided by the information in the PV module data sheet and are known quantities.

V _oc (T)=V _oc(STC) + k _v (TT _STC ) (16)

The first diode reverse saturation current I _o1 and the second diode reverse saturation current I _o2 mainly depend on changes in the ambient temperature. The conversion methods of these two parameters are shown in equations (17) and (18), respectively.

In equations (17) and (18), E _g is the band gap width of silicon cells, E _g(STC) is the band gap width of silicon cells under standard conditions (E _g(STC) = 1.121 eV), E _g depends on The relationship between ambient temperature and ambient temperature is represented by equation (19).

E _g ＝E _g(STC) {1-0.0002677(TT _STC )} (19)

The series resistance R _s and the parallel resistance R _sh can be expressed by equations (20) and (21) at any ambient temperature:

R _s ＝R _s(STC) (20)

The photo-generated current I _ph of photovoltaic modules depends on the ambient temperature and irradiance, and the specific relationship is shown in equation (22).

The relationship between short-circuit current and ambient radiance is expressed by equation (23), and the relationship between open circuit voltage and ambient radiance can be derived from equation (2), as shown in equation (24).

The maximum power point voltage V _mp and the open circuit voltage V _oc have an approximately linear relationship as shown in equation (25)

V _mp = k _oc V _oc (25)

In formula (25), k _oc is the proportional coefficient, and its value is generally between 0.71 and 0.80.

In the photovoltaic system, exp(V _oc /N _s V _t )>>exp(I _sc R _s /N _s V _t ), so the formula (11) can be simplified, as shown in the formula (26).

Combining equations (12) and (26) can get the expressions of dual diode reverse saturation currents I _o1 and I _o2 , as shown in equations (27) and (28):

Where: Q=(1+(R _s /R _sh ))I _sc -(V _oc /R _sh ),

R=(1+(R _s /R _sh ))(I _sc -I _mp )-(V _mp /R _sh ).

Substitute the values of I _o1 and I _o2 into formulas (10) and (14) to obtain formulas (29) and (30).

Among them: Q ₁ =(1-(I _mp /V _mp )), Q ₂ =((V _oc -V _mp -I _mp R _s )/2N _s V _t ;

Among them: Q ₃ =(I _sc R _s -V _oc )/2N _s V _t , Q ₄ =(V _mp +I _mp R _s )/2N _s V _t , Q ₅ =(V _mp -V _oc +I _mp R _s )/2N _s V _t .

In summary, two nonlinear equations (28) and (29) are finally obtained, which contain only two unknown parameters R _s and R _sh . The unknown parameters are obtained by solving the equations by the LM algorithm, and the unknown parameters are solved by the LM algorithm As described in formula (31).

x _i+1 = x _i -(J ^T (x _i )J(x _i )+λI) ^-1 J ^T (x _i )e(x _i ) (31)

Where x _i is the current weight factor, x _i+1 is the next weight factor, J ^T (x _i ) (=H(x _i )) is the Hessian matrix at x _i , and e(x _i ) is the error vector , Λ is the combination coefficient.

The LM algorithm combines the advantages of the gradient descent method and the Gauss-Newton method. At the beginning of the iteration, the LM algorithm behaves as a gradient descent method to take advantage of its low sensitivity to the initial value. When the calculated value is close to the final solution, it is again Gaussian -Newton's method to achieve the effect of rapid convergence, the switching between them is controlled by the parameter λ.

After the error of the algorithm is given in the update (31), compare it with the previous error: if the error decreases, λ is reduced by 10 times to reduce the gradient; otherwise, if the error increases, λ is increased by 10 times to increase the gradient . Once the algorithm converges, the values of R _s and R _sh will be output. The specific flowchart is shown in Figure 2.

S201: Initialize R _s and R _sh , tolerance=1×10 ^-8 , and the number of iterations i=1.

S202: Calculate E(x _i ) according to E(x _i )=max[abs(f ₁ ;f ₂ )], where x _i =R _s or R _sh .

S203: calculating x _i Jacobian matrix J (x _i).

S204: Calculate x _i+1 = x _i -(J ^T (x _i )J(x _i )+λI) ^-1 J ^T (x _i )e(x _i ).

S205: x _{i +} calculated error E (x _{i + 1) 1} in.

S206: Judge whether E(x _i+1 ) is less than tolerance; if E(x _i+1 )<tolerance, execute step S207, if E(x _i+1 )≥ tolerance, execute step S208.

S207: Output the values R _{s (STC)} and R _{sh (STC) of} R _s and R _sh under standard conditions.

S208: Determine whether E(x _i+1 ) is less than E(x _i ), if E(x _i+1 )<E(x _i ), go to step S209. If E(x _i+1 )≥E(x _i ), perform step S210.

S209: Take the value corresponding to 1/10 of λ, and return to step S203.

S210: Take the value corresponding to 10 times of λ, and return to step S203.

S211: Substitute R _{s (STC)} and R _{sh (STC)} into formulas (3), (27) and (28) to obtain the values of I _o1 , I _o2 and I _ph under standard conditions, namely I _{o1 (STC)} , I _o2(STC) and I _ph(STC) .

S212: Convert R _{s (STC)} , R _{sh (STC)} , I _{o1 (STC)} , I _{o2 (STC)} and I _{ph (STC)} under standard conditions to the current environmental conditions.

S213: Substitute the values of R _s , R _sh , I _o1 , I _o2 and I _ph under the current environmental conditions into formulas (16) and (24) to determine the value of the open circuit voltage V _oc under the current environmental conditions V _oc ( G, T).

S214: Substitute the values of R _s , R _sh , I _o1 , I _o2 , I _ph and V _oc under the current environmental conditions into formulas (10) and (25) to determine V _mp and _Imp .

S215: Determine the maximum power of the photovoltaic power generation system P _mp =V _mp ×I _mp .

In an embodiment, the value of the initialized R _s can be determined according to the following formula (33):

And, the value of the initialized R _sh can be determined according to the following formula (34):

To estimate the maximum power of the photovoltaic system, the traditional method needs to go through two iterations. First, the unknown parameters of the photovoltaic system are solved by an iterative method, and then converted to the current working environment, and finally, the maximum is solved by an iterative method. power. The iterative solution method will be affected by the selection of the initial value, resulting in a greater risk of iteration failure, and the two iterative processes will take a long time. The maximum power estimation method of the photovoltaic power generation system provided in this article uses the LM algorithm to first calculate the unknown parameters , To avoid the problem of improper selection of the initial value, and then use the approximate open-circuit voltage method to calculate the maximum power point voltage to obtain the maximum power.

Claims (11)

1. A method for estimating the maximum power of a photovoltaic power generation system, including:

   According to the Shockley diffusion theory, the ideality factor A1 of the first diode is 1 and the ideality factor A2 of the second diode is 2 in the formula for determining the photovoltaic output current of the dual diode model of the photovoltaic cell;

   According to the determined A1 and A2, determine the first nonlinear equation set f ₁ and the second nonlinear equation set f ₂ , where both f ₁ and f ₂ include series resistance R _s , parallel resistance R _sh , first two Five parameters: the reverse saturation current I _o1 of the diode, the reverse saturation current I _{o2 of the} second diode, and the photovoltaic module photo-generated current I _ph ;

   Initialize the values of R _s and R _sh ;

   Values R _s and R _sh initialization obtained, and f ₁ and f _2, and determining the error R _s R _sh in accordance with a parameter;

   The error of the determined R _s and R _sh in a parameter, determining the error in the R _s and R _sh other parameters;

   Judge whether the error of another parameter in the determined R _s and R _sh is less than the tolerance value;

   In response to determining that the error of the other parameter of R _s and R _sh is less than the tolerance value, determine the values of R _s and R _sh under standard conditions;

   Determine the value of I _o1 , the value of I _{o2 and} the value of I _ph under the standard conditions according to the determined values of R _s and R _sh under the standard conditions;

   According to the value of R _s , R _sh , I _o1 , I _o2 , and I _ph under the standard conditions, determine the value of R _s , R _sh , and I _o1 under the current environmental conditions , I _o2 value and I _ph value;

   According to the determined value of R _s , R _sh , I _o1 , I _o2 and I _ph under the current environmental conditions, determine the maximum power P _mp of the photovoltaic power generation system under the current environmental conditions .
2. The method of claim 1, wherein the initializing the values of R _s and R _sh includes:

   Determine the value of the initialized R _s according to the following formula:

   

   Wherein, V _{oc (STC)} is the value of the open circuit voltage under the standard conditions, V _{mp (STC)} is the value of the maximum power point voltage of the photovoltaic power generation system under the standard conditions, and _{Imp (STC)} is the standard The value of the current at the maximum power point of the photovoltaic power generation system under the conditions, and I _{sc (STC)} is the value of the short-circuit current under the standard conditions;

   Determine the value of the initialized R _sh according to the following formula:

   
3. The method as claimed in claim 2, wherein the initialization value according to the obtained R _s and R _sh, and f ₁ and F _2, R _s and R _sh is determined in one error parameter, comprising:

   Substituting the value of R _{s and} the value of R _sh obtained by the initialization into f ₁ and f ₂ ;

   According to the following calculation formula, calculate the error E(x _i ) of the current weighting factor x _i :

   E(x _i )=max[abs(f ₁ ; f ₂ )]

   Among them, x _i = R _s or R _sh .
4. The method according to claim 3, wherein, according to the determined error of R _s and R _sh in a parameter, determining the error in the R _s and R _sh another parameter, comprising:

   X _i is calculated Jacobian matrix J (x _i);

   Calculate x _i+1 =x _i -(J ^T (x _i )J(x _i )+λI) ^-1 J ^T (x _i )e(x _i ),

   Among them, J ^T (x _i ) is the inverse matrix of J(x _i ), λ is the combination coefficient, I is the photovoltaic output current, and e(x _i ) is the error vector of E(x _i ), when x _i =R _s When x _i+1 =R _sh , when x _i =R _sh , x _i+1 =R _s ;

   X _{i + 1} is calculated error E (x _{i + 1).}
5. The method of claim 4, wherein the determining the value of R _s and R _sh under standard conditions in response to determining that the error of the other parameter of R _s and R _sh is less than the tolerance value comprises:

   In response to determining E(x _i+1 )<tolerance, the values R _s(STC) and R _{sh(STC) of} R _s and R _sh under standard conditions are output.
6. The method according to claim 5, wherein after determining whether the error of the other parameter of R _s and R _sh is less than the tolerance value, the method further comprises:

   In response to determining that E (x _{i + 1)} ≥tolerance and _{E (x i + 1) <} E (x i), then substituting a value corresponding to 1/10 λ x _i into the calculation of the Jacobian matrix J (x Step _i ) recalculate until E(x _i+1 )<tolerance, and output the values R _s(STC) and R _{sh(STC) of} R _s and R _sh in the standard state;

   In response to determining that E (x _{i + 1)} ≥tolerance and _{E (x i + 1) ≥E} (x i), then passaged 10 times the value of λ corresponding to x _i into the calculation of the Jacobian matrix J (x _i ) Is recalculated until E(x _i+1 )<tolerance, and the values R _s(STC) and R _{sh(STC) of} R _s and R _sh in the standard state are output.
7. The method of claim 5, wherein the value of I _o1 , the value of I _o2 , and the value of I _ph are determined under the standard conditions according to the determined values of R _s and R _sh under the standard conditions ,include:

   Substitute R _s(STC) and R _sh(STC) into the following three calculation formulas to determine the value I _o1(STC) of the first double diode reverse saturation current I _o1 under the standard conditions. The value I _{o2 (STC) of the} reverse saturation current I _o2 of the first double diode and the value I _ph(STC) of the photovoltaic module photo-generated current I _ph under the standard conditions:

   

   

   

   Among them, Q=(1+(R _s /R _sh ))I _sc -(V _oc /R _sh ), R=(1+(R _s /R _sh ))(I _sc -I _mp )-(V _mp /R _sh ), N _s is the number of photovoltaic modules connected in series, V _t =kT/q, k is Boltzmann's constant (1.308×10 ^-23 J/K), q is electronic charge (1.602×10 ^-19 C) , T is the ambient temperature under the standard conditions, V _oc is the open circuit voltage under the standard conditions, V _mp is the maximum power point voltage under the standard conditions, and _Imp is the maximum power point under the standard conditions Current.
8. The method according to claim 7, wherein the value of R _s , the value of R _sh , the value of I _o1 , the value of I _{o2 and} the value of I _ph under the standard conditions are used to determine R under the current environmental conditions. The value of _s , the value of R _sh , the value of I _o1 , the value of I _{o2 and} the value of I _ph include:

   Determine the value of R _s under the current environmental conditions according to the following formula:

   R _s ＝R _s(STC)

   Determine the value of R _sh under the current environmental conditions according to the following formula:

   

   Wherein, G _STC is the radiance under the standard conditions, and G is the radiance under the current environmental conditions;

   Determine the value of I _o1 under the current environmental conditions according to the following formula:

   

   Among them, E _g is the band gap width of the silicon cell, E _{g (STC)} is the band gap width of the silicon cell under standard conditions, E _{g (STC)} = 1.121 eV, E _g = E _{g (STC)} {1-0.0002677 (TT _STC )};

   Determine the value of I _o2 under the current environmental conditions according to the following formula:

   

   Determine the value of I _ph under the current environmental conditions according to the following formula:

   

   Among them, k _i is the short-circuit current temperature coefficient.
9. The method according to claim 8, wherein the current value of R _s , the value of R _sh , the value of I _o1 , the value of I _{o2 and} the value of I _ph are determined based on the determined current environmental conditions. The maximum power P _mp of the photovoltaic power generation system under environmental conditions includes:

   Substitute the values of R _s , R _sh , I _o1 , I _o2 and I _ph under the current environmental conditions into the following two calculation formulas to determine the value of the open circuit voltage V _oc under the current environmental conditions V _oc (G,T ):

   V _oc (T) = V _{oc (STC)} + k _v (TT _STC )

   

   Among them, k _v is the open circuit voltage coefficient, V _t =kT/q, k is Boltzmann's constant (1.308×10 ^-23 J/K), q is the electronic charge (1.602×10 ^-19 C), and T is the The ambient temperature under the current environmental conditions, and G is the radiance under the current environmental conditions;

   Substitute the values of R _s , R _sh , I _o1 , I _o2 , I _ph and V _oc under the current environmental conditions into the following two formulas to calculate the maximum power point voltage V _mp and maximum power under the current environmental conditions Point current I _mp :

   

   V _mp ＝k _oc V _oc

   Among them, k _oc is the proportional coefficient;

   The maximum power P _mp of the photovoltaic power generation system under current environmental conditions is calculated according to the following calculation formula:

   P _mp =V _mp ×I _mp .
10. The method of claim 9, wherein k _oc is any value from 0.71 to 0.80.
11. The method according to any one of claims 1-10, wherein the tolerance value is equal to 1×10 ^-8 .

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