Disclosure of Invention
The invention mainly aims to provide a method and a system for predicting the generated energy of a photovoltaic power station based on a neural network, which are based on Weibull distribution of service life and failure probability of a photovoltaic module in the use process, comprehensively consider the running state of a power station when the photovoltaic module fails to predict the generated energy, correct a predicted value output through a neural network model, output a predicted expected value of the generated energy, better accord with the actual running condition of the photovoltaic power station, improve the accuracy of a predicted result and effectively solve the problems in the background art.
In order to achieve the above purpose, the invention adopts the technical proposal that,
a method for estimating the generating capacity of a photovoltaic power station based on a neural network comprises the following steps,
step one, collecting operation parameter data of a photovoltaic module in a photovoltaic power station, wherein the operation parameter data comprise operation time and fault probability values;
fitting the operation parameter data by using a cumulative distribution function and a probability density function of the double-parameter Weibull distribution to obtain estimated values of the shape parameters and the scaling factors, and calculating estimated values of the position parameters according to the estimated values of the shape parameters and the scaling factors;
step three, the obtained shape parameters and scale parameters are brought into a Weibull distribution model, the expression of the model is,
wherein F (x) is a distribution function; x is a random variable; η is a scaling factor; β is a shape parameter; γ is a location parameter; predicting failure probability F (x) of ith group of photovoltaic modules through model i Wherein i=1, 2., n, n is the total number of photovoltaic modules;
step four, collecting history of the photovoltaic power stationData are used as input to construct a prediction model, and the generated energy predicted value P of the ith group of photovoltaic modules of the photovoltaic power station in the time interval t is output through the model i ;
Step five, calculating a total power generation amount correction value P according to the prediction result of the failure probability of the photovoltaic module and the total power generation amount prediction value c Correction value P of total power generation c The calculation formula of (a) is as follows,
wherein F (t) e ) i Denoted as the ith group of photovoltaic modules at the end time t of time interval t e Is a failure probability of (1); f (t) b ) i Denoted as the ith group of photovoltaic modules at an initial instant t of time interval t b Is a failure probability of (1); f (t) e ) i -F(t b ) i Expressed as the probability of failure of the ith group of photovoltaic modules within the time interval t.
A neural network-based photovoltaic power plant power generation capacity estimation system, comprising:
the photovoltaic module monitoring module is used for monitoring the operation state of the photovoltaic module in real time and collecting the operation parameter data of the photovoltaic module in the photovoltaic power station, including the operation time and the fault probability value;
the fault analysis module is connected with the photovoltaic module monitoring module and is used for calculating the failure probability of the photovoltaic module according to the Weibull distribution model and the operation parameter data of the photovoltaic module;
the data acquisition module is used for acquiring historical data of the photovoltaic power station;
the data analysis module is connected with the data acquisition module and is used for preprocessing the acquired data, carrying out correlation analysis on the data of each influence factor and the corresponding generated energy data, and acquiring the influence factors positively correlated with the generated energy;
the power generation amount prediction module takes collected historical data of the photovoltaic power station as input to construct a prediction model, and the model is used for the predictionOutput of the predicted value P of the power generation amount of the ith group of photovoltaic modules of the photovoltaic power station within the time interval t i ;
The correction prediction module calculates a total power generation amount correction value P according to a prediction result of the failure probability of the photovoltaic module and a total power generation amount prediction value c Wherein the total power generation amount correction value P c The calculation formula of (a) is as follows,
wherein F (t) e ) i Denoted as the ith group of photovoltaic modules at the end time t of time interval t e Is a failure probability of (1); f (t) b ) i Denoted as the ith group of photovoltaic modules at an initial instant t of time interval t b Is a failure probability of (1); f (t) e ) i -F(t b ) i Expressed as the probability of failure of the ith group of photovoltaic modules within the time interval t.
The system also includes a memory, a processor, and an electronic program stored in the memory and capable of running on the processor.
The invention has the following advantages that,
compared with the prior art, the technical scheme of the invention has the advantages that the operation parameter data of the photovoltaic module in the photovoltaic power station are collected, the operation state of the photovoltaic power station when the failure occurs to the photovoltaic module is comprehensively considered, the Weibull distribution model of the service life of the photovoltaic module in the use process is constructed, the failure probability of the photovoltaic module in the use process in the future time interval is predicted through the model, the historical data of the photovoltaic power station is collected as input to construct a prediction model, the power generation predicted value of the photovoltaic module of the photovoltaic power station in the time interval is output through the prediction model, the total power generation correction value is calculated according to the predicted result of the failure probability of the photovoltaic module and the total power generation predicted value, and the power generation predicted expected value is used as the final output power generation predicted result, so that the method is more in line with the actual operation situation of the photovoltaic power station, and the accuracy of the predicted result is improved.
Detailed Description
The present invention will be further described with reference to the following detailed description, wherein the drawings are for illustrative purposes only and are presented as schematic drawings, rather than physical drawings, and are not to be construed as limiting the invention, and wherein certain components of the drawings are omitted, enlarged or reduced in order to better illustrate the detailed description of the present invention, and are not representative of the actual product dimensions.
Example 1
The flow chart of the method for estimating the generated energy of the photovoltaic power station based on the neural network and the overall structure block diagram of the system for estimating the generated energy of the photovoltaic power station based on the neural network, which are provided by the technical scheme of the invention and are shown in the figure 1.
The technical proposal adopted by the invention is that,
a method for estimating the generating capacity of a photovoltaic power station based on a neural network comprises the following steps,
step one, collecting operation parameter data of a photovoltaic module in a photovoltaic power station, wherein the operation parameter data comprise operation time and fault probability values;
fitting the operation parameter data by using a cumulative distribution function and a probability density function of the double-parameter Weibull distribution to obtain estimated values of the shape parameters and the scaling factors, and calculating estimated values of the position parameters according to the estimated values of the shape parameters and the scaling factors;
step three, the obtained shape parameters and scale parameters are brought into a Weibull distribution model, the expression of the model is,
wherein F (x) is a distribution function; x is a random variable; η is a scaling factor; β is in the shape ofParameters; γ is a location parameter; predicting failure probability F (x) of ith group of photovoltaic modules through model i Wherein i=1, 2., n, n is the total number of photovoltaic modules;
step four, collecting historical data of the photovoltaic power station as input to construct a prediction model, and outputting a power generation quantity predicted value P of an ith group of photovoltaic modules of the photovoltaic power station within a time interval t through the model i ;
Step five, calculating a total power generation amount correction value P according to the prediction result of the failure probability of the photovoltaic module and the total power generation amount prediction value c Correction value P of total power generation c The calculation formula of (a) is as follows,
wherein F (t) e ) i Denoted as the ith group of photovoltaic modules at the end time t of time interval t e Is a failure probability of (1); f (t) b ) i Denoted as the ith group of photovoltaic modules at an initial instant t of time interval t b Is a failure probability of (1); f (t) e ) i -F(t b ) i Expressed as the probability of failure of the ith group of photovoltaic modules within the time interval t.
A neural network-based photovoltaic power plant power generation capacity estimation system, comprising:
the photovoltaic module monitoring module is used for monitoring the operation state of the photovoltaic module in real time and collecting the operation parameter data of the photovoltaic module in the photovoltaic power station, including the operation time and the fault probability value;
the fault analysis module is connected with the photovoltaic module monitoring module and is used for calculating the failure probability of the photovoltaic module according to the Weibull distribution model and the operation parameter data of the photovoltaic module;
the data acquisition module is used for acquiring historical data of the photovoltaic power station;
the data analysis module is connected with the data acquisition module and is used for preprocessing the acquired data, carrying out correlation analysis on the data of each influence factor and the corresponding generated energy data and acquiring the influence factors positively correlated with the generated energy;
the power generation amount prediction module takes collected historical data of the photovoltaic power station as input to construct a prediction model, and outputs a power generation amount predicted value P of an ith group of photovoltaic modules of the photovoltaic power station within a time interval t through the model i ;
The correction prediction module calculates a total power generation amount correction value P according to a prediction result of the failure probability of the photovoltaic module and a total power generation amount prediction value c Wherein the total power generation amount correction value P c The calculation formula of (a) is as follows,
wherein F (t) e ) i Denoted as the ith group of photovoltaic modules at the end time t of time interval t e Is a failure probability of (1); f (t) b ) i Denoted as the ith group of photovoltaic modules at an initial instant t of time interval t b Is a failure probability of (1); f (t) e ) i -F(t b ) i Expressed as the probability of failure of the ith group of photovoltaic modules within the time interval t.
The system also includes a memory, a processor, and an electronic program stored in the memory and capable of running on the processor.
The specific implementation flow of the technical scheme of the invention comprises the following steps:
step 1), monitoring the operation state of a photovoltaic module in real time through a photovoltaic module monitoring module, and collecting operation parameter data of the photovoltaic module in a photovoltaic power station, wherein the operation parameter data comprises operation time and a fault probability value;
step 2), fitting operation parameter data by using a cumulative distribution function and a probability density function of double-parameter Weibull distribution through a fault analysis module to obtain estimated values of shape parameters and scaling factors, and calculating estimated values of position parameters according to the estimated values of the shape parameters and the scaling factors, wherein the cumulative distribution function and the probability density function of Weibull distribution are expressed as follows:
CDF:
PDF:
wherein CDF is a cumulative distribution function expression; PDF is a probability density function expression; t is a time variable;
the calculation formula of the scale parameter formula of Weibull distribution is as follows:
step 3), the obtained shape parameters and scale parameters are brought into a Weibull distribution model, the expression of the model is,
wherein F (x) is a distribution function; x is a random variable; η is a scaling factor; beta is a shape parameter; gamma is a position parameter; predicting failure probability F (x) of ith group of photovoltaic modules through model i The method comprises the steps that i=1, 2, n and n are the total number of photovoltaic modules, and it is required to be noted that at present, most of detection certification authorities utilize an acceleration test method to analyze weather resistance and reliability of outdoor operation of the photovoltaic modules, and failure modes of the photovoltaic modules are analyzed through wet-freeze acceleration tests of the photovoltaic modules, and test results show that service lives and failure probabilities of the photovoltaic modules accord with Weibull distribution, so that the failure probabilities of the photovoltaic modules in a photovoltaic power station can be predicted by adopting a Weibull distribution model;
step 4), acquiring historical data of the photovoltaic power station as input through a power generation amount prediction module to construct a prediction model, and outputting a power generation amount predicted value P of an ith group of photovoltaic modules of the photovoltaic power station within a time interval t through the model i The method comprises the following specific steps of:
step 41, obtaining historical power generation data with the length of c, and preprocessing the obtained data to obtain the historical power generation numberThe data set X, expressed as: x= [ X ] 1 ,...,x t-1 ,x t ,...,x n ] T ;
Step 42, training the historical wind power data set X as input to construct a first neural network model, and extracting and outputting influence factor characteristics positively related to the generated energy in the historical wind power data set X through the constructed model;
step 43, training and constructing a second neural network model by taking the influence factor characteristics output by the first neural network model as input, learning the influence factor characteristic output rule by the second neural network model, and outputting a power generation quantity prediction result;
in actual operation, the model construction can be performed through a BP neural network tool in MATLAB, and the steps are as follows:
a, collecting historical power generation data of a photovoltaic power generation system, wherein the historical power generation data comprises month, day length, weather, time, radiation quantity, real-time temperature, humidity, wind power, wind direction, illumination intensity, current, voltage of a photovoltaic cell array and the like, and corresponding photovoltaic power output data, and the fact that the calculation quantity of a model is overlarge due to various types in the historical power generation data is required to be screened, the acquired data are preprocessed through a data analysis module, correlation analysis is carried out on the data of all the influence factors and corresponding generated energy data, and the influence factors positively correlated with generated energy are obtained, and the method comprises the following specific steps:
step a1, collecting data of all possible influencing factors and corresponding generating capacity data;
step a2, preprocessing the acquired data to acquire a data set X of each influencing factor i Corresponding generated energy data set Y i Wherein, the method comprises the steps of, wherein,x ij a j-th value expressed as an i-th influencing factor;y ij represented as the ith shadowGenerating capacity data corresponding to the j-th value of the response factor;
step a3, calculating correlation coefficients r of data of each influencing factor and corresponding generating capacity data respectively i Wherein r is i Is the first i The correlation coefficient of the term influence factors and the generated energy is calculated as follows:
wherein,is the first i The mean value of the term impact factor data; />Is the first i The average value of the generated energy corresponding to the item influence factors, j is the number of samples;
step a4, screening influence factors larger than 0 in the calculation result of the correlation coefficient as influence factors positively correlated with the generated energy;
b, preprocessing the collected data, including data cleaning, normalization processing and the like;
c, establishing a neural network model of photovoltaic power prediction by using a BP neural network tool box in MATLAB;
d, determining input layer variables and output layer variables of the neural network;
e, designing hidden layers of the neural network, wherein the hidden layers comprise the number of the hidden layers and the number of nodes;
f, selecting a proper training algorithm and training parameters;
g, training a neural network model by using the preprocessed historical data;
h, testing and verifying the trained neural network model by using the test data set;
the first neural network model can be a CNN model, has two characteristics of parameter sharing and sparse connection, can effectively capture the characteristics of original data, and the second neural network model can be a BiLSTM model, predicts subsequent information by utilizing forward information, and combines forward and backward information of an input sequence on the basis of LSTM to improve prediction accuracy;
step 5), calculating a total power generation amount correction value P according to the prediction result of the failure probability of the photovoltaic module and the total power generation amount prediction value through a correction prediction module c Correction value P of total power generation c The calculation formula of (a) is as follows,
wherein F (t) e ) i Denoted as the ith group of photovoltaic modules at the end time t of time interval t e Is a failure probability of (1); f (t) b ) i Denoted as the ith group of photovoltaic modules at an initial instant t of time interval t b Is a failure probability of (1); f (t) e ) i -F(t b ) i The failure probability of the photovoltaic module of the ith group in the time interval t is expressed, and it is required to be stated that, because the service life and the failure probability of the photovoltaic module conform to Weibull distribution in the use process, when the power generation amount of a future period is predicted, the situation when the photovoltaic module fails also needs to be considered, and therefore, the total power generation amount correction value P is calculated c The predicted value output by the neural network model is corrected, the predicted expected value of the generated energy in the future time interval t is output, the predicted value is more in line with the actual running condition of the photovoltaic power station, and the prediction accuracy of the predicted result is correspondingly improved.
The foregoing has shown and described the basic principles and main features of the present invention and the advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.