WO2020211370A1 - Maximum photovoltaic power estimation method for photovoltaic power generation system - Google Patents
Maximum photovoltaic power estimation method for photovoltaic power generation system Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
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- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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- 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.
- photovoltaic power generation occupies an important position in energy development.
- 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.
- 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.
- the dual-diode model is a seven-parameter model, so seven parameters need to be solved.
- 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.
- the present disclosure provides a method for estimating the maximum power of a photovoltaic power generation system.
- the method includes the following steps:
- 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;
- 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 ;
- the method for estimating the maximum power of a photovoltaic power generation system based on a dual-diode model 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.
- Fig. 1 is a flowchart of a method for estimating the maximum power of a photovoltaic power generation system according to an embodiment
- FIG. 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.
- 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.
- the method for estimating the maximum power of a photovoltaic power generation system includes the following steps.
- 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.
- FIG. 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 of a photovoltaic cell, as shown in FIG. 2 and FIG. 3.
- the photovoltaic output current can be expressed by 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
- 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
- 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.
- 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.
- 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.
- STC short-circuit current
- k i is the temperature coefficient of short-circuit current
- k v is the open-circuit voltage temperature coefficient.
- 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.
- E g is the band gap width of silicon cells
- E g depends on The relationship between ambient temperature and ambient temperature is represented by equation (19).
- 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).
- V mp k oc V oc (25)
- k oc is the proportional coefficient, and its value is generally between 0.71 and 0.80.
- R (1+(R s /R sh ))(I sc -I mp )-(V mp /R sh ).
- 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 .
- x i is the current weight factor
- x i+1 is the next weight factor
- e(x i ) is the error vector
- ⁇ is the combination coefficient.
- the LM algorithm combines the advantages of the gradient descent method and the Gauss-Newton method.
- the LM algorithm behaves as a gradient descent method to take advantage of its low sensitivity to the initial value.
- 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 ⁇ .
- S207 Output the values R s (STC) and R sh (STC) of R s and R sh under standard conditions.
- 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.
- the value of the initialized R s can be determined according to the following formula (33):
- the value of the initialized R sh can be determined according to the following formula (34):
- the traditional method needs to go through two iterations.
- 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.
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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 Rs and Rsh; according to the values of Rsand Rsh obtained by means of initialization and f1 and f2, determining an error of one parameter of Rs and Rsh; according to the determined error of the parameter of Rs and Rsh, determining an error of the other parameter of Rs and Rsh; determining whether the determined error of the other parameter of Rs and Rsh is less than a tolerance value; in response to the determination that the error of the other parameter of Rs and Rsh is less than the tolerance value, determining the values of Rs and Rsh under standard conditions; and according to the determined values of Rs and Rsh under the standard conditions, determining the maximum power Pmp of a photovoltaic power generation system under the current environmental conditions.
Description
本申请要求在2019年04月15日提交中国专利局、申请号为201910299193.8的中国专利申请的优先权,该申请的全部内容通过引用结合在本申请中。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.
本公开属于光伏发电技术领域,具体涉及一种光伏发电系统最大功率估计方法。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.
光伏发电作为重要的可再生能源发电技术,在能源发展中占有重要地位。随着光伏发电占比的逐渐增大,电网对光伏发电系统的可调控能力提出了越来越高的要求。光伏发电系统最大功率估计,是通过数值计算的方法得到光伏可输出最大功率,从而便于电网下达调度指令调控,防止光伏发电系统因输出功率波动过大对电网造成过大冲击而导致脱网并造成弃光和威胁电网稳定性的问题。光伏发电系统最大功率估计(Maximum Photovoltaic Power Estimation,MPPE)需要先对光伏电池和模块进行建模分析,其中,光伏单二极管模型(也被称为五参数模型)以其较高的准确性和较低的计算难度而被广泛使用,但是,光伏单二极管模型在低太阳辐射和开路电压的情况下,精度会大幅度降低。光伏双二极管模型通过在光伏单二极管模型中并联另外一个二极管来补偿重组损失,从而提高建模的精度。但双二极管模型为七参数模型,因此需要求解七个参数,然而光伏输出特性为非线性超越方程,求解过程中出现迭代失败风险较大,传统的线性近似方法在低辐射环境下会带来较大误差,从而无法保证预测精度,也即是很难既保证求解过程中迭代收敛又保证求解的精度。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.
发明内容Summary of the invention
本公开提供一种光伏发电系统最大功率估计方法,该方法包括以下步骤:The present disclosure provides a method for estimating the maximum power of a photovoltaic power generation system. The method includes the following steps:
根据肖克利扩散理论,确定光伏电池双二极管模型的光伏输出电流的表达公式中的第一二极管的理想因子A1为1、第二二极管的理想因子A2为2;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;
根据确定出的A1和A2,确定第一非线性方程组f
1和第二非线性方程组f
2,其中,f
1和f
2中都包括串联电阻R
s、并联电阻R
sh、第一二极管反向饱和电流I
o1、第二二极管反向饱和电流I
o2以及光伏组件光生电流I
ph这五个参数;
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 ;
初始化R
s和R
sh的值;
Initialize the values of R s and R sh ;
根据初始化得到的R
s和R
sh的值,以及f
1和f
2,确定R
s和R
sh中一个参数的误差;
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;
根据确定出的R
s和R
sh中一个参数的误差,确定R
s和R
sh中另一个参数的误差;
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;
判断确定出的R
s和R
sh中另一个参数的误差是否小于公差值;
Judge whether the error of another parameter in the determined R s and R sh is less than the tolerance value;
响应于确定R
s和R
sh中另一个参数的误差小于所述公差值,确定标准条件下R
s和R
sh的值;
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;
根据确定出的所述标准条件下R
s和R
sh的值,确定所述标准条件下I
o1的值、I
o2的值和I
ph的值;
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;
根据所述标准条件下R
s的值、R
sh的值、I
o1的值、I
o2的值和I
ph的值,确定当前环境条件下R
s的值、R
sh的值、I
o1的值、I
o2的值和I
ph的值;
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;
根据确定出的所述当前环境条件下R
s的值、R
sh的值、I
o1的值、I
o2的值和I
ph的值,确定所述当前环境条件下的光伏发电系统最大功率P
mp。
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 .
本文的有益效果在于:The beneficial effects of this article are:
本公开提供的基于双二极管模型的光伏发电系统最大功率估计方法,通过 建立光伏电池的双二极管7参数模型,并采用开路电压和短路电流参数实现环境参数向标准条件的转换计算;通过使用参数控制的L-M算法,使得该算法分段表现出梯度下降法和高斯-牛顿法的特性,并充分结合两种方法的优点;基于L-M算法的光伏双二极管模型参数计算,受迭代初始值选取影响较小,并且加快了收敛速度和精度;基于开路电压近似的方法求得最大功率值,省去了一次迭代的过程提升了计算速度。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.
图1为一实施例提供的光伏发电系统最大功率估计方法的流程图;Fig. 1 is a flowchart of a method for estimating the maximum power of a photovoltaic power generation system according to an embodiment;
图2为另一实施例提供的光伏发电系统最大功率估计方法的流程图;2 is a flowchart of a method for estimating the maximum power of a photovoltaic power generation system according to another embodiment;
图3为一实施例提供的双二极管模型等效电路。FIG. 3 is an equivalent circuit of a dual diode model provided by an embodiment.
列文伯格-马夸尔特(Levenberg-Marquard,L-M)算法结合了高斯-牛顿法和梯度下降法的优点,并对两者之不足之处进行了改善,保证了迭代收敛的速度和精度。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 .
图1为一实施例提供的光伏发电系统最大功率估计方法的流程图,参见图1,该光伏发电系统最大功率估计方法包括如下步骤。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、根据肖克利扩散理论,确定光伏电池双二极管模型的光伏输出电流的表达公式中的第一二极管的理想因子A1为1、第二二极管的理想因子A2为2。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、根据确定出的A1和A2,确定第一非线性方程组f
1和第二非线性方程组f
2,其中,f
1和f
2中都包括串联电阻R
s、并联电阻R
sh、第一二极管反向饱和电流I
o1、第二二极管反向饱和电流I
o2以及光伏组件光生电流I
ph这五个参数。
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、初始化R
s和R
sh的值。
S103. Initialize the values of R s and R sh .
S104、根据初始化得到的R
s和R
sh的值,以及f
1和f
2,确定R
s和R
sh中一个参数的误差。
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、根据确定出的R
s和R
sh中一个参数的误差,确定R
s和R
sh中另一个参数的误差。
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、判断确定出的R
s和R
sh中另一个参数的误差是否小于公差值。
S106: Judge whether the error of another parameter among the determined R s and R sh is less than the tolerance value.
S107、响应于确定R
s和R
sh中另一个参数的误差小于所述公差值,确定标准条件下R
s和R
sh的值。
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、根据确定出的所述标准条件下R
s和R
sh的值,确定所述标准条件下I
o1的值、I
o2的值和I
ph的值。
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、根据所述标准条件下R
s的值、R
sh的值、I
o1的值、I
o2的值和I
ph的值,确定当前环境条件下R
s的值、R
sh的值、I
o1的值、I
o2的值和I
ph的值。
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、根据确定出的所述当前环境条件下R
s的值、R
sh的值、I
o1的值、I
o2的值和I
ph的值,确定所述当前环境条件下的光伏发电系统最大功率P
mp。
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 .
图2为另一实施例提供的光伏发电系统最大功率估计方法的流程图,图3为光伏电池双二极管模型等效电路,如图2和图3所示。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.
光伏输出电流可以由式(1)表示:The photovoltaic output current can be expressed by formula (1):
式(1)中I
ph为光伏组件光生电流;I
o1为第一二极管D
1反向饱和电流,I
o2为第二二极管反向饱和电流;I
d1为流过第一二极管D
1的电流和I
d2为流过第二二极管D
2的电流;I
Rsh为流过并联电阻的电流;R
s为串联电阻,R
sh为并联电阻;V为光伏电池输出电压和I为光伏电池输出电流;A
1为第一二极管D
1理想因子, A
2为第二二极管D
2理想因子;N
s为光伏组件串联数;V
t=kT/q,k为玻尔兹曼常数(1.308×10
-23J/K);q为电子电荷(1.602×10
-19C);T为环境温度。
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.
为减少计算非线性方程的计算时间和复杂程度,根据肖克利扩散理论,可取式(1)中A
1=1和A
2=2,简化后双二极管模型七个未知参数{I
ph,I
o1,I
o2,R
sh,R
s,A
1,A
2}简化成五个{I
ph,I
o1,I
o2,R
sh,R
s}。这五个参数可以通过光伏组件制造厂家提供的数据表信息计算得到,数据表所提供的三个重要的参数为在标准条件下光伏模型I-V曲线上恒过三点,如表1所示(仅考虑统一光照条件下)分别是开路电压(V
oc,0),短路电流(0,I
sc)和最大功率点电压和电流(V
mp,I
mp),可以通过迭代求解的方法求出这五个参数。
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.
表1光伏组件数据表以及需求解参数Table 1 PV module data sheet and demand solution parameters
表1中k
i为短路电流系数,k
v为开路电压系数,N
s为光伏组件串联数,N
p为光伏组件并联数。将上述三点与A
1=1和A
2=2代入到式(1)中,可以得到(2)-(4)式:
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:
为获取五个参数,还需要更多的方程,在光伏组件I-V曲线上任意一点的输出功率均可由式(5)表示,并且已知在(V
mp,I
mp)点处电压对功率的导数为0可以得到式(6)-(8)。
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)P=VI (5)
将式(1)对电压求导并代入到式(8)中得到式(9)-(10):Taking the formula (1) to the voltage and substituting it into the formula (8) to obtain the formula (9)-(10):
在式(2)中表示出了I
ph的值,将其代入到式(3)-(4)中,得到式(11)-(12):
The value of I ph is expressed in formula (2), and it is substituted into formulas (3)-(4) to obtain formulas (11)-(12):
式(10)-(12)中有{I
o1,I
o2,R
sh,R
s}四个参数,R
sh的值可以由光伏V-I曲线电压对电流的导数在短路电流点处表示,并代入到式(9)中,得到式(13)-(14)。
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.
实际运行过程中需要将每个参数转换到当前的环境条件下。短路电流和开路电压与温度呈线性关系,如式(15)和(16)所示,式中带“STC”下标的均表示在标准条件下的参数值,k
i为短路电流温度系数,k
v为开路电压温度系数,这两个参数在标准条件下的值由光伏组件数据表信息提供,为已知量。
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(T-T
STC) (16)
V oc (T)=V oc(STC) + k v (TT STC ) (16)
第一二极管反向饱和电流I
o1和第二二极管反向饱和电流I
o2主要取决于环境温度变化,这两个参数换算方法分别如式(17)和(18)所示。
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.
式(17)和(18)中E
g为硅电池的带隙宽度,E
g(STC)为硅电池在标准条件下的带隙宽度(E
g(STC)=1.121eV),E
g取决于环境温度,其与环境温度关系由式(19)表示。
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(T-T
STC)} (19)
E g =E g(STC) {1-0.0002677(TT STC )} (19)
串联电阻R
s和并联电阻R
sh在任意的环境温度下均可由式(20)和(21)表示:
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)
R s =R s(STC) (20)
光伏组件的光生电流I
ph取决于环境温度和辐射度,其具体关系如式(22)所示。
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).
短路电流与环境辐射度的关系由式(23)表示,开路电压与环境辐射度的关系可以由式(2)推导,如式(24)所示。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).
最大功率点电压V
mp与开路电压V
oc存在近似线性关系如式(25)所示
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
ocV
oc (25)
V mp = k oc V oc (25)
式(25)中k
oc为比例系数,其取值一般在0.71~0.80之间。
In formula (25), k oc is the proportional coefficient, and its value is generally between 0.71 and 0.80.
在光伏系统中有exp(V
oc/N
sV
t)>>exp(I
scR
s/N
sV
t),因此可对式(11)简化,如式(26)所示。
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).
结合式(12)和(26)可以得出双二极管反向饱和电流I
o1和I
o2的表达式,如式(27)和(28)所示:
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):
其中:Q=(1+(R
s/R
sh))I
sc-(V
oc/R
sh),
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)。
R=(1+(R s /R sh ))(I sc -I mp )-(V mp /R sh ).
将I
o1和I
o2的值代入到式(10)和(14)中得到式(29)和(30)。
Substitute the values of I o1 and I o2 into formulas (10) and (14) to obtain formulas (29) and (30).
其中:Q
1=(1-(I
mp/V
mp)),Q
2=((V
oc-V
mp-I
mpR
s)/2N
sV
t;
Among them: Q 1 =(1-(I mp /V mp )), Q 2 =((V oc -V mp -I mp R s )/2N s V t ;
其中:Q
3=(I
scR
s-V
oc)/2N
sV
t,Q
4=(V
mp+I
mpR
s)/2N
sV
t,Q
5=(V
mp-V
oc+I
mpR
s)/2N
sV
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 .
综上所述,最终得到两个非线性方程组(28)和(29),式中只包含两个未知参数R
s和R
sh,通过L-M算法求解方程组获得未知参数,L-M算法求解未知参数如式(31)所描述。
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)
-1J
T(x
i)e(x
i) (31)
x i+1 = x i -(J T (x i )J(x i )+λI) -1 J T (x i )e(x i ) (31)
式中x
i为当前权重因子,x
i+1为下一个权重因子,J
T(x
i)(=H(x
i))为在x
i处的Hessian矩阵,e(x
i)为误差向量,λ为组合系数。
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.
L-M算法结合了梯度下降法和高斯-牛顿法的优点,在迭代开始时L-M算法表现为梯度下降法,以利用其对初始值选取低灵敏度的优势,当计算值接近最终解时又表现为高斯-牛顿法以达到快速收敛的效果,其之间的切换受参数λ控制。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.
在更新(31)中给出算法的误差之后,与上一次误差做对比:如果误差减小则λ减小10倍以减小梯度下降;否则,如果误差增加,则λ增加10倍以增加梯度。一旦算法收敛,将输出R
s和R
sh的值,其具体流程图如图2所示。
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:初始化R
s和R
sh,公差值tolerance=1×10
-8,迭代次数i=1。
S201: Initialize R s and R sh , tolerance=1×10 -8 , and the number of iterations i=1.
S202:根据E(x
i)=max[abs(f
1;f
2)],计算E(x
i),其中x
i=R
s或R
sh。
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:计算x
i的雅克比矩阵J(x
i)。
S203: calculating x i Jacobian matrix J (x i).
S204:计算x
i+1=x
i-(J
T(x
i)J(x
i)+λI)
-1J
T(x
i)e(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:计算x
i+1的误差E(x
i+1)。
S205: x i + calculated error E (x i + 1) 1 in.
S206:判断E(x
i+1)是否小于tolerance;若E(x
i+1)<tolerance,执行步骤S207,若E(x
i+1)≥tolerance,执行步骤S208。
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:输出R
s和R
sh在标准条件下的值R
s(STC)和R
sh(STC)。
S207: Output the values R s (STC) and R sh (STC) of R s and R sh under standard conditions.
S208:判断E(x
i+1)是否小于E(x
i),若E(x
i+1)<E(x
i),执行步骤S209。若E(x
i+1)≥E(x
i),执行步骤S210。
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:取λ的1/10对应的数值,返回步骤S203。S209: Take the value corresponding to 1/10 of λ, and return to step S203.
S210:取λ的10倍对应的数值,返回步骤S203。S210: Take the value corresponding to 10 times of λ, and return to step S203.
S211:将R
s(STC)和R
sh(STC)代入式(3)、(27)和(28),得到标准条件下的I
o1,I
o2和I
ph的值,即I
o1(STC),I
o2(STC)和I
ph(STC)。
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:将标准条件下的R
s(STC),R
sh(STC),I
o1(STC),I
o2(STC)和I
ph(STC)转换到当前环境条件下。
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:将当前环境条件下的R
s,R
sh,I
o1,I
o2和I
ph的值代入式(16)和(24)中,确定当前环境条件下的开路电压V
oc的值V
oc(G,T)。
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:将当前环境条件下的R
s,R
sh,I
o1,I
o2,I
ph和V
oc的值代入式(10)和(25)中,确定V
mp和I
mp。
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:确定光伏发电系统最大功率P
mp=V
mp×I
mp。
S215: Determine the maximum power of the photovoltaic power generation system P mp =V mp ×I mp .
一实施例中,可以根据如下公式(33)确定初始化的R
s的值:
In an embodiment, the value of the initialized R s can be determined according to the following formula (33):
并且,可以根据如下公式(34)确定初始化的R
sh的值:
And, the value of the initialized R sh can be determined according to the following formula (34):
估计光伏系统最大功率,传统的方法需要经过两次迭代的过程,首先通过一次迭代方法求解出光伏系统的未知参数,然后转换到当前工况环境下,最后还需要通过一次迭代的方法求解出最大功率。迭代求解的方法会受到初始值选取影响而造成迭代失败的风险较大,并且两次迭代过程需要耗费较长的时间,本文提供的光伏发电系统最大功率估计方法通过使用L-M算法先计算出未知参 数,避免了初始值选取不当的问题,然后使用近似开路电压的方法计算出最大功率点电压从而获得最大功率。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)
- 一种光伏发电系统最大功率估计方法,包括:A method for estimating the maximum power of a photovoltaic power generation system, including:根据肖克利扩散理论,确定光伏电池双二极管模型的光伏输出电流的表达公式中的第一二极管的理想因子A1为1、第二二极管的理想因子A2为2;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;根据确定出的A1和A2,确定第一非线性方程组f 1和第二非线性方程组f 2,其中,f 1和f 2中都包括串联电阻R s、并联电阻R sh、第一二极管反向饱和电流I o1、第二二极管反向饱和电流I o2以及光伏组件光生电流I ph这五个参数; 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 ;初始化R s和R sh的值; Initialize the values of R s and R sh ;根据初始化得到的R s和R sh的值,以及f 1和f 2,确定R s和R sh中一个参数的误差; 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;根据确定出的R s和R sh中一个参数的误差,确定R s和R sh中另一个参数的误差; 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;判断确定出的R s和R sh中另一个参数的误差是否小于公差值; Judge whether the error of another parameter in the determined R s and R sh is less than the tolerance value;响应于确定R s和R sh中另一个参数的误差小于所述公差值,确定标准条件下R s和R sh的值; 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;根据确定出的所述标准条件下R s和R sh的值,确定所述标准条件下I o1的值、I o2的值和I ph的值; 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;根据所述标准条件下R s的值、R sh的值、I o1的值、I o2的值和I ph的值,确定当前环境条件下R s的值、R sh的值、I o1的值、I o2的值和I ph的值; 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;根据确定出的所述当前环境条件下R s的值、R sh的值、I o1的值、I o2的值和I ph的值,确定所述当前环境条件下的光伏发电系统最大功率P mp。 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 .
- 如权利要求1所述的方法,其中,所述初始化R s和R sh的值,包括: The method of claim 1, wherein the initializing the values of R s and R sh includes:根据如下公式确定初始化的R s的值: Determine the value of the initialized R s according to the following formula:其中,V oc(STC)为所述标准条件下开路电压的值,V mp(STC)为所述标准条件下所述光伏发电系统最大功率点电压的值,I mp(STC)为所述标准条件下所述光伏发电系统最大功率点电流的值,I sc(STC)为所述标准条件下短路电流的值; 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;根据如下公式确定初始化的R sh的值: Determine the value of the initialized R sh according to the following formula:
- 如权利要求2所述的方法,其中,所述根据初始化得到的R s和R sh的值,以及f 1和f 2,确定R s和R sh中一个参数的误差,包括: 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:将所述初始化得到的R s的值和R sh的值代入f 1和f 2中; Substituting the value of R s and the value of R sh obtained by the initialization into f 1 and f 2 ;根据如下计算公式,计算当前权重因子x i的误差E(x i): 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)] E(x i )=max[abs(f 1 ; f 2 )]其中,x i=R s或R sh。 Among them, x i = R s or R sh .
- 如权利要求3所述的方法,其中,所述根据确定出的R s和R sh中一个参数的误差,确定R s和R sh中另一个参数的误差,包括: 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:计算x i的雅克比矩阵J(x i); X i is calculated Jacobian matrix J (x i);计算x i+1=x i-(J T(x i)J(x i)+λI) -1J T(x i)e(x i), Calculate x i+1 =x i -(J T (x i )J(x i )+λI) -1 J T (x i )e(x i ),其中,J T(x i)为J(x i)的逆矩阵,λ为组合系数,I为光伏输出电流,e(x i)为E(x i)的误差向量,当x i=R s时,x i+1=R sh,当x i=R sh时,x i+1=R s; 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 ;计算x i+1的误差E(x i+1)。 X i + 1 is calculated error E (x i + 1).
- 如权利要求4所述的方法,其中,所述响应于确定R s和R sh中另一个参数的误差小于所述公差值,确定标准条件下R s和R sh的值,包括: 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:响应于确定E(x i+1)<公差值tolerance,输出R s和R sh在标准条件下的值R s(STC) 和R sh(STC)。 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.
- 如权利要求5所述的方法,其中,所述判断确定出的R s和R sh中另一个参数的误差是否小于公差值之后,还包括: 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:响应于确定E(x i+1)≥tolerance且E(x i+1)<E(x i),则将λ的1/10对应的数值代入所述计算x i的雅克比矩阵J(x i)的步骤重新计算,直至E(x i+1)<tolerance,输出R s和R sh在所述标准状态下的值R s(STC)和R sh(STC); 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;响应于确定E(x i+1)≥tolerance且E(x i+1)≥E(x i),则将λ的10倍对应的数值代入所述计算x i的雅克比矩阵J(x i)的步骤重新计算,直至E(x i+1)<tolerance,输出R s和R sh在所述标准状态下的值R s(STC)和R sh(STC)。 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.
- 如权利要求5所述的方法,其中,所述根据确定出的所述标准条件下R s和R sh的值,确定所述标准条件下I o1的值、I o2的值和I ph的值,包括: 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:将R s(STC)和R sh(STC)代入如下三个计算公式,确定所述标准条件下的第一双二极管反向饱和电流I o1的值I o1(STC),所述标准条件下的第一双二极管反向饱和电流I o2的值I o2(STC)和所述标准条件下的光伏组件光生电流I ph的值I ph(STC): 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:其中,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为光伏组件串联数,V t=kT/q,k为玻尔兹曼常数(1.308×10 -23J/K),q为电子电荷(1.602×10 -19C),T为所述标准条件下的环境温度,V oc为所述标准条件下的开路电压,V mp为所述标准条件下的最大功率点电压,I mp为所述标准条件下的最大 功率点电流。 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.
- 如权利要求7所述的方法,其中,所述根据所述标准条件下R s的值、R sh的值、I o1的值、I o2的值和I ph的值,确定当前环境条件下R s的值、R sh的值、I o1的值、I o2的值和I ph的值,包括: 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:根据如下公式确定所述当前环境条件下的R s的值: Determine the value of R s under the current environmental conditions according to the following formula:R s=R s(STC) R s =R s(STC)根据如下公式确定所述当前环境条件下的R sh的值: Determine the value of R sh under the current environmental conditions according to the following formula:其中,G STC为所述标准条件下的辐射度,G为所述当前环境条件下的辐射度; Wherein, G STC is the radiance under the standard conditions, and G is the radiance under the current environmental conditions;根据如下公式确定所述当前环境条件下的I o1的值: Determine the value of I o1 under the current environmental conditions according to the following formula:其中,E g为硅电池的带隙宽度,E g(STC)为硅电池在标准条件下的带隙宽度,E g(STC)=1.121eV,E g=E g(STC){1-0.0002677(T-T STC)}; 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 )};根据如下公式确定所述当前环境条件下的I o2的值: Determine the value of I o2 under the current environmental conditions according to the following formula:根据如下公式确定所述当前环境条件下的I ph的值: Determine the value of I ph under the current environmental conditions according to the following formula:其中,k i为短路电流温度系数。 Among them, k i is the short-circuit current temperature coefficient.
- 如权利要求8所述的方法,其中,根据确定出的所述当前环境条件下R s的值、R sh的值、I o1的值、I o2的值和I ph的值,确定所述当前环境条件下的光伏发电系统最大功率P mp,包括: 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:将所述当前环境条件下的R s,R sh,I o1,I o2和I ph的值代入如下两个计算公式确定所述当前环境条件下的开路电压V oc的值V oc(G,T): 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(T-T STC) V oc (T) = V oc (STC) + k v (TT STC )其中,k v为开路电压系数,V t=kT/q,k为玻尔兹曼常数(1.308×10 -23J/K),q为电子电荷(1.602×10 -19C),T为所述当前环境条件下的环境温度,G为所述当前环境条件下的辐射度; 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;将所述当前环境条件下的R s,R sh,I o1,I o2,I ph和V oc的值代入到如下两个公式计算所述当前环境条件下的最大功率点电压V mp和最大功率点电流I mp: 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 ocV oc V mp =k oc V oc其中,k oc为比例系数; Among them, k oc is the proportional coefficient;根据如下计算公式计算得到所述当前环境条件下的光伏发电系统最大功率P mp: 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。 P mp =V mp ×I mp .
- 如权利要求9所述的方法,其中,k oc为0.71至0.80中的任一数值。 The method of claim 9, wherein k oc is any value from 0.71 to 0.80.
- 如权利要求1-10任一项所述的方法,其中,所述公差值等于1×10 -8。 The method according to any one of claims 1-10, wherein the tolerance value is equal to 1×10 -8 .
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