CN111325325A - Method for predicting electric energy substitution potential based on genetic algorithm and BP neural network combination - Google Patents

Method for predicting electric energy substitution potential based on genetic algorithm and BP neural network combination Download PDF

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CN111325325A
CN111325325A CN202010104951.9A CN202010104951A CN111325325A CN 111325325 A CN111325325 A CN 111325325A CN 202010104951 A CN202010104951 A CN 202010104951A CN 111325325 A CN111325325 A CN 111325325A
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陈巨龙
刘振铭
廖志军
郑方鹏
薛毅
姚刚
刘凡
张裕
代江
段声志
陈皓勇
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Abstract

The invention provides a method for predicting electric energy substitution potential based on genetic algorithm and BP neural network combination, which comprises the following steps: defining electric energy substitution quantity describing electric energy substitution potential, and determining relevant factors influencing the electric energy substitution quantity; quantifying relevant factors influencing the electric energy substitution quantity; determining a BP neural network structure; optimizing initial weight and threshold of the BP neural network by using the data of the past year through a genetic algorithm, and training the BP neural network; the method has high prediction precision, can effectively support the prediction of the electric energy substitution amount, and provides quantitative theoretical guidance for subsequent electric energy substitution related work.

Description

Method for predicting electric energy substitution potential based on genetic algorithm and BP neural network combination
Technical Field
The invention relates to the technical field of electric power research, in particular to a method for predicting electric energy substitution potential based on genetic algorithm and BP neural network combination.
Background
At present, the electric energy substitution is in a terminal energy consumption link, and the electric energy is used for substituting an energy consumption mode of burning coal and fuel oil, so that the electric energy substitution has great significance for promoting the energy consumption revolution and reducing the atmospheric pollution. The electric energy substitution is beneficial to improving the air quality, is also beneficial to improving the electrification level of China, is beneficial to improving the added value of products in partial industrial industries, and is more beneficial to improving the life quality of people.
With the increasing population scale and economic quantity of China, the energy consumption is increased day by day, and the ecological environment is obviously influenced. The serious pollution phenomenon is the result of unreasonable energy development mode, long-time accumulation and concentrated outbreak of structural contradiction in China, and the solution of the environmental problem needs to change the energy structure mainly based on coal, reduce the utilization of fossil energy, control the total energy and adjust the structure of energy consumption. In order to realize sustainable development and establish green economy, China develops electric energy substitution work which takes electricity to replace coal, electricity to replace oil and electricity from a distance and clean electricity as core content. Researches show that 50-60% of air pollution PM 2.5 is from fire coal and 20-30% is from fuel oil, and electric energy has the characteristics and advantages of cleanness, safety, convenience, wide sources and the like, so that the consumption proportion of the electric energy in terminal energy sources is increased, the combustion emission of the terminal fossil energy sources is reduced, and severe environmental pressure is relieved. When implementing clean substitution at the energy supply side, optimize consumption structure at the energy consumption side, replace coal (salary) with electricity, replace oil with electricity, replace gas with electricity, advocate the new mode of energy consumption, constantly improve the proportion that the electric energy accounts for terminal energy consumption, optimize energy structure, promote energy saving and emission reduction, promote environmental quality and economic sustainable development ability.
Under the background, electric energy substitution faces a hard-to-obtain historical opportunity, the electric energy accounts for a lower proportion of terminal energy consumption at present, and the energy-saving and environment-friendly effects of an energy terminal utilization link have a multiple amplification effect, so that the electric energy substitution needs to be promoted in order. In order to provide theoretical guidance for planning work of subsequent power supplies, power grids and capacity, it is necessary to evaluate the electric energy substitution potential of each region and make a corresponding electric energy substitution propulsion strategy.
Disclosure of Invention
This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and the title of the invention of this application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.
Therefore, the technical problem to be solved by the invention is to overcome the defect that no system for effectively carrying out theoretical guidance on planning of a power supply, a power grid and capacity and evaluating the electric energy substitution potential of each region exists in the prior art, so that the method for predicting the electric energy substitution potential based on the combination of the genetic algorithm and the BP neural network is provided.
In order to solve the technical problems, the invention provides the following technical scheme: a method for predicting electric energy substitution potential based on genetic algorithm and BP neural network combination is characterized in that: the method comprises the following steps: defining electric energy substitution quantity for describing electric energy substitution potential; determining relevant factors influencing the electric energy substitution amount, and quantifying the relevant factors influencing the electric energy substitution amount; determining a BP neural network structure; optimizing the initial weight and threshold of the artificial neural network through a genetic algorithm; and predicting the electric energy substitution amount through the trained BP neural network.
As a preferable scheme of the method for predicting the electric energy substitution potential based on the combination of the genetic algorithm and the BP neural network, the method comprises the following steps: the electric energy substitution amount is an objective basis for realizing quantitative calculation and analysis of electric energy substitution potential, and is a process of continuously accumulating and advancing, namely historical technical and policy measures and the like still influence the future, so the accumulated electric energy substitution amount of each year is calculated on the basis to quantitatively represent the electric energy substitution process, the actual electric energy consumption in the t year is Ef (t), the total terminal energy consumption is Eq (t), if the energy pattern for the terminal maintains the level of the t year, the proportion of electric energy occupied by the electric energy in the terminal is the same as that in the t year, the electric energy consumption increment in the t +1 year compared with that in the previous year is defined as the electric energy substitution amount in the t +1 year, and specific expressions of the electric energy substitution amount and the accumulated electric energy substitution amount are respectively as follows:
Figure BDA0002388229590000021
E(t)=∑Esub(t)
in the formula: esub(t +1) is the electric energy replacement amount in the t +1 th year; ef(t +1) is the actual power consumption in the t +1 th year; eq(t +1) is the total terminal energy consumption in the t +1 th year; e (t) is the accumulated electric energy replacement amount of the t year and is the sum of the electric energy replacement amounts before the t year.
As a preferable scheme of the method for predicting the electric energy substitution potential based on the combination of the genetic algorithm and the BP neural network, the method comprises the following steps: the factors influencing the electric energy replacement process are many, and main influencing factors are selected for analysis, namely the four influencing factors of economic development, electric energy replacement technology development, environmental protection and policy guidance, and the specific analysis is as follows:
the economic development factor and the power demand have an inseparable relationship, so that the total value of all production of people is selected to reflect the influence of economic development on electric energy substitution in the electric energy substitution process in China, and the specific expression is as follows:
Figure BDA0002388229590000031
in the formula: gAve(t) represents the total per capita production value of the t year; g (t) represents the total production value of the t year; p (t) represents the total population in the t year.
The progress of the electric energy substitution technology can promote the progress of electric energy substitution development, so the ratio of actual electric energy consumption to theoretical electric energy consumption is selected to measure the development level of the electric energy substitution technology, and the specific expression is as follows:
Figure BDA0002388229590000032
wherein η (t) represents the ratio of actual power consumption to theoretical power consumption in the t-th year, E1(t) represents an actual power consumption amount of the t year; p (t) represents the theoretical power consumption in the t year.
The environmental protection nature mainly includes that sulfur dioxide and powder (cigarette) dirt come from the substituted influence of electric energy, so carry out the analysis through the emission of sulfur dioxide and powder (cigarette) dirt, because the emission of sulfur dioxide and powder (cigarette) dirt is different to the substituted influence of electric energy, so increase the weight coefficient to the emission of sulfur dioxide and powder (cigarette) dirt respectively and carry out the gross quantization, specific expression is:
H(t)=αH1(t)+βH2(t)
wherein H (t) represents the total pollutant emission amount after the quantification in the t year, α represents a weight coefficient of the influence of the sulfur dioxide pollutant on the electric energy substitution in the quantification process, H1(t) represents the total pollutant emission amount of the sulfur dioxide pollutant in the atmosphere in the t year, β represents a weight coefficient of the influence of the dust pollutant on the electric energy substitution in the quantification process, and H2(t) represents the total pollutant emission amount of the dust pollutant in the atmosphere in the t year.
The policy-oriented main expression is that the competitiveness of electric energy in a terminal energy market is improved by strengthening electric power construction and subsidy policies and improving the economy of the electric energy, so that the influence of the policy on the electric energy substitution development is expressed by selecting the ratio of the investment of a newly-built energy fixed asset, and the specific expression is as follows:
Figure BDA0002388229590000033
in the formula: m (t) represents the ratio of the investment of the newly built electric fixed assets to the investment of the newly built energy fixed assets in the t year; fe (t) represents the investment of the newly built electric power fixed assets in the t year; f (t) represents the investment of the energy fixed assets newly built in the t year.
As a preferable scheme of the method for predicting the electric energy substitution potential based on the combination of the genetic algorithm and the BP neural network, the method comprises the following steps: the BP neural network consists of two processes of forward propagation of data flow and backward propagation of error signals, the propagation direction is input layer → hidden layer → output layer during the forward propagation, the state of each layer of neuron only affects the next layer of neuron, if the expected output can not be obtained at the output layer, the backward propagation process of the error signals is turned, through the alternate operation of the two processes, the error function gradient descent strategy is executed in the weight vector space, a group of weight vectors are dynamically and iteratively searched, the network error function reaches the minimum value, thereby completing the information extraction and memory process,
because the unit of the input data is different, the range of some data may be particularly large, resulting in slow convergence of the neural network, long training time, and limited value range of the activation function of the output layer of the neural network, normalization of the data is required, and the data is mapped to the [0,1] interval, where the specific expression is:
Figure BDA0002388229590000041
in the formula: y is data after x normalization; xmin is the minimum value of x; xmax being the maximum value of x
Predicting by using a feedforward three-layer network, wherein an input layer of the network has 4 nodes, a hidden layer has q nodes, an output layer has 1 node, the weight between the input layer and the hidden layer is vki, the weights between the hidden layer and the output layer are wk, bk and b which are respectively thresholds of the hidden layer and the output layer, the transfer function of the hidden layer is f1, the transfer function of the output layer is f2,
the output specific expression of the hidden node is:
Figure BDA0002388229590000042
the specific expression of the output layer node is as follows:
Figure BDA0002388229590000043
the BP neural network completes the approximate mapping of the 4-dimensional space vector to the 1-dimensional space, and the neural network structure is determined.
As a preferable scheme of the method for predicting the electric energy substitution potential based on the combination of the genetic algorithm and the BP neural network, the method comprises the following steps: in order to make the error function of the BP neural network reach the minimum value, therefore defining the error function, supposing that P groups of training data are input, because the node of the output layer is 1, yp is the output of the network, adopting the mean square error function, the error of the P groups of training data can be obtained, and the specific expression is as follows:
Figure BDA0002388229590000051
in the formula, p is the number of training samples;
Figure BDA0002388229590000052
an expected output value for the network; yp is the actual output value of the network,
adjusting w using accumulated error BP algorithmjkAnd reducing the global error MSE, wherein the specific expression is as follows:
Figure BDA0002388229590000053
wherein η is the learning rate,
and continuously iterating and correcting the weight until the error meets the requirement, namely:
wjk=wjk+Δwjk
as a preferable scheme of the method for predicting the electric energy substitution potential based on the combination of the genetic algorithm and the BP neural network, the method comprises the following steps: the BP neural network has low learning speed and convergence speed and is easy to fall into a local minimum value, so that the initial weight and the threshold of the BP neural network are optimized by adopting the genetic algorithm, the optimized BP neural network can better predict function output, the BP neural network is optimized by adopting the genetic algorithm to obtain better initial weight and threshold of the network, the basic idea is to use the initial weight and the threshold of an individual representative network and the prediction error of the BP neural network initialized by individual values as the fitness value of the individual, and the optimal individual, namely the optimal initial weight and the threshold of the BP neural network, is searched by selection, intersection and mutation operations.
As a preferable scheme of the method for predicting the electric energy substitution potential based on the combination of the genetic algorithm and the BP neural network, the method comprises the following steps: coding the weight value from the input layer to the hidden layer, the hidden layer threshold value, the weight value from the hidden layer to the output layer and the output layer threshold value by acquiring the BP neural network structure information, wherein a floating point number coding mode is adopted, and the coding length is as follows:
L=inputnum*hiddennum+hiddennum+hiddennum*outputnum+outputnum
=4q+q+q+1
=6q+1
in the formula: l is the code length; inputnum is the number of neurons in the input layer; hiddennum is the number of hidden layer neurons; output number is the number of output layer neurons,
initializing a group, and adopting the reciprocal of the square sum of the predicted value and the true value as a fitness function, wherein the specific expression is:
Figure BDA0002388229590000061
In the formula: p is the number of training samples;
Figure BDA0002388229590000062
an expected output value for the network; y ispThe actual output value of the network.
As a preferable scheme of the method for predicting the electric energy substitution potential based on the combination of the genetic algorithm and the BP neural network, the method comprises the following steps: the method for predicting the electric energy substitution amount through the trained BP neural network mainly comprises the following steps: quantizing the relevant influence factors predicted in the year, and performing data normalization on the quantized data to obtain data input into the neural network; inputting the prediction data to the trained BP neural network to obtain an output prediction value; and performing data inverse normalization on the output predicted value to obtain the predicted value of the electric energy substitute quantity.
As a preferable scheme of the method for predicting the electric energy substitution potential based on the combination of the genetic algorithm and the BP neural network, the method comprises the following steps: the prediction precision is improved by using the genetic algorithm and BP neural network combination prediction.
The invention has the beneficial effects that:
the invention provides a method for predicting electric energy substitution potential based on combination of a genetic algorithm and a BP neural network, which quantifies electric energy substitution influence related factors, predicts electric energy substitution quantity through combination of the genetic algorithm and an artificial neural network algorithm, can effectively support prediction of the electric energy substitution quantity, and provides quantitative theoretical guidance for subsequent electric energy substitution related work.
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In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise. Wherein:
FIG. 1 is a flow chart of a method for predicting electric energy substitution potential based on a combination of a genetic algorithm and a BP neural network;
FIG. 2 is a partial flowchart of the initial weight and threshold algorithm of the BP neural network;
FIG. 3 is a comparison graph of the real value and the predicted value of the accumulated electric energy substitution amount between 2006 and 2013;
FIG. 4 is a comparison graph of the real value and the predicted value of the accumulated energy substitution amount between 2014 and 2017;
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.
The invention provides a method for predicting electric energy substitution potential based on genetic algorithm and BP neural network combination, which comprises the following steps:
defining electric energy substitution quantity, and describing electric energy substitution potential:
further, in order to realize quantitative calculation of the electric energy substitution potential, the electric energy substitution amount is defined as an objective basis for analyzing the electric energy substitution potential. If the actual electric energy consumption in the t year is ef (t), the total energy consumption of the terminal is Eq (t), and if the energy pattern for the terminal maintains the level of the t year, the proportion of the electric energy occupied by the terminal is the same as that in the t year, the electric energy consumption increase in the t +1 year compared with the electric energy consumption increase in the previous year is defined as the electric energy replacement in the t +1 year.
Figure BDA0002388229590000071
In the formula: esub(t +1) electric energy substitution for the t +1 yearAn amount; ef(t +1) is the actual power consumption in the t +1 th year; eq (t +1) is the total terminal energy consumption in the t +1 th year.
Because the electric energy replacement is a process which is continuously accumulated and promoted, namely historical technical and policy measures and the like still have influence on the future, the accumulated electric energy replacement amount of each year is calculated on the basis to quantitatively represent the electric energy replacement process:
E(t)=∑Esub(t)
wherein E (t) is the cumulative electric energy replacement amount of the t year and is the sum of the electric energy replacement amounts of the t year before
Determining relevant factors influencing the electric energy substitution amount, and quantifying the relevant factors influencing the electric energy substitution amount;
furthermore, there are many factors influencing the electric energy replacement process, and the main influencing factors are selected for analysis, namely, the four influencing factors are economic development, electric energy replacement technology development, environmental protection and policy guidance.
The development of economy is not energy-saving. The power demand and economic growth of China have a close and inseparable relationship, and researches show that the two variables have a stable relationship. Therefore, the total value of all the selected people is used for reflecting the influence of economic development on electric energy substitution in the electric energy substitution process in China:
Figure BDA0002388229590000072
in the formula: gAve(t) represents the total per capita production value of the t year; g (t) represents the total production value of the t year; p (t) represents the total population in the t year.
The electric energy substitution related technology is also an important factor for limiting the development of electric energy substitution, and the progress of the technology can push the progress of the electric energy substitution development. Therefore, the ratio of the actual power consumption to the theoretical power consumption is selected to measure the development level of the power substitution technology:
Figure BDA0002388229590000081
wherein η (t) represents the t-th yearA ratio of actual power consumption to theoretical power consumption; e1(t) represents an actual power consumption amount of the t year; p (t) represents the theoretical power consumption in the t year.
Further, the electric energy substitution can reduce pollutants such as sulfur dioxide, dust (smoke) and the like in the atmosphere, and is beneficial to environmental protection. There is therefore a certain amount of correlation between the amount of pollutants such as sulphur dioxide and the amount of replacement for electrical energy. Therefore, by analyzing the emission amount of sulfur dioxide and dust (smoke), the emission amount of sulfur dioxide and dust (smoke) has different influences on electric energy substitution, so that the weight coefficients are respectively added to the emission amounts of sulfur dioxide and dust (smoke) for overall quantification.
H(t)=αH1(t)+βH2(t)
Wherein H (t) represents the total pollutant emission amount after the quantification in the t year, α represents a weight coefficient of the influence of the sulfur dioxide pollutant on the electric energy substitution in the quantification process, H1(t) represents the total pollutant emission amount of the sulfur dioxide pollutant in the atmosphere in the t year, β represents a weight coefficient of the influence of the dust pollutant on the electric energy substitution in the quantification process, and H2(t) represents the total pollutant emission amount of the dust pollutant in the atmosphere in the t year.
Further, the electric energy substitution work is not pushed away from the government policy guidance, and the main expression is to improve the competitiveness of electric energy in the terminal energy market by strengthening electric power construction, subsidizing policies and improving the economy of electric energy. The ratio of the new energy fixed asset investments (including electricity, coal, oil and gas) was chosen to represent the impact of policy on the development of electric energy substitution.
Figure BDA0002388229590000082
In the formula: m (t) represents the ratio of the investment of the newly built electric fixed assets to the investment of the newly built energy fixed assets in the t year; fe(t) represents the investment of the newly built electric fixed assets in the t year; f (t) represents the investment of the energy fixed assets newly built in the t year.
Determining a BP neural network structure:
the BP neural network consists of two processes of forward propagation of data streams and backward propagation of error signals. In forward propagation, the propagation direction is input layer → hidden layer → output layer, and the state of each layer of neurons only affects the next layer of neurons. If the desired output is not available at the output layer, the back propagation flow of the error signal is reversed. By alternately carrying out the two processes, an error function gradient descending strategy is executed in the weight vector space, and a group of weight vectors are dynamically and iteratively searched, so that the network error function reaches the minimum value, and the information extraction and memory processes are finished.
Further, since the units of input data are different, the range of some data may be particularly large, resulting in slow convergence of the neural network, long training time, and limited value range of the activation function of the output layer of the neural network. Therefore, the data needs to be normalized and mapped to the [0,1] interval:
Figure BDA0002388229590000091
in the formula: y is data after x normalization; x is the number ofminIs the minimum value of x; x is the number ofmaxIs the maximum value of x.
Furthermore, a feedforward three-layer network is used for prediction, an input layer of the network has 4 nodes, a hidden layer of the network has q nodes, an output layer of the network has 1 node, the weight between the input layer and the hidden layer is vki, and the weight between the hidden layer and the output layer is wk,bkAnd b are the threshold values of the hidden layer and the output layer respectively. The transfer function of the hidden layer is f1The transfer function of the output layer is f2
The output of the hidden node is:
Figure BDA0002388229590000092
the output of the output layer node is:
Figure BDA0002388229590000093
the BP network completes the approximate mapping of the 4-dimensional space vector to the 1-dimensional space, and the neural network structure is determined.
Further, an error function is defined, assuming an input P set of training data, since the output layer nodes are 1, ypThat is, the error of the P sets of training data can be obtained by using the mean square error function as the output of the network:
Figure BDA0002388229590000094
in the formula, p is the number of training samples;
Figure BDA0002388229590000101
an expected output value for the network; y isp-the actual output value of the network.
Adjusting w using accumulated error BP algorithmjkThe global error MSE is made smaller, i.e.:
Figure BDA0002388229590000102
wherein η is the learning rate.
And continuously iterating and correcting the weight until the error meets the requirement:
wjk=wjk+Δwjk
further, optimizing the initial weight and the threshold of the artificial neural network through a genetic algorithm:
the BP neural network has low learning speed and convergence speed and is easy to fall into a local minimum value, so that the initial weight and the threshold of the BP neural network are optimized by adopting a genetic algorithm, the optimized BP neural network can better predict function output, the BP neural network is optimized by adopting the genetic algorithm to obtain better initial weight and threshold of the BP neural network, the basic idea is that the initial weight and the threshold of an individual representative network and the prediction error of the BP neural network initialized by individual values are used as the fitness value of the individual, and the optimal individual, namely the optimal initial weight and the threshold of the BP neural network, are searched by selection, intersection and mutation operations.
Acquiring BP network structure information, coding a weight from an input layer to a hidden layer, a hidden layer threshold, a weight from the hidden layer to an output layer and an output layer threshold, and adopting a floating point number coding mode and a coding length:
L=inputnum*hiddennum+hiddennum+hiddennum*outputnum+outputnum
=4q+q+q+1
=6q+1
in the formula: l is the code length; inputnum is the number of neurons in the input layer; hiddennum is the number of hidden layer neurons; output number is the number of neurons in the output layer.
And initializing a group, and adopting the reciprocal of the square sum of the predicted value and the true value as a fitness function.
Figure BDA0002388229590000103
In the formula: p is the number of training samples;
Figure BDA0002388229590000104
an expected output value for the network; y ispThe actual output value of the network.
Further, the electric energy substitution amount is predicted through the trained BP neural network, and the following steps are carried out:
s1: quantizing the relevant influence factors predicted in the year, and performing data normalization on the quantized data to obtain data input into the neural network;
s2: inputting the prediction data to the trained BP neural network to obtain an output prediction value;
s3: and performing data inverse normalization on the output predicted value to obtain the predicted value of the accumulated electric energy substitute quantity.
Application example
The development condition of electric energy substitution is analyzed by using the electric energy substitution related data in 2006-2017 of China, and is specifically shown in the following table:
Figure BDA0002388229590000111
selecting data in 2006 + 2013 as training data, and optimizing the initial weight and threshold of the neural network through a genetic algorithm to obtain a fitting graph of the accumulated electric energy substitute quantity in 2006 + 2012:
Figure BDA0002388229590000121
the mean square error between the prediction result and the actual result in 2006-2013 is only 0.000100, which indicates that the fitting degree is high.
The validity of the algorithm is verified by using the data of 2014-2017. And inputting the relevant influence factor data in 2014-2017 into the trained neural network to obtain a comparison graph of the actual value and the predicted value of the accumulated electric energy substitution amount in 2013-2016.
Figure BDA0002388229590000122
The mean square deviation between the prediction result and the actual result in 2014-2017 is 97020.525872, which shows that the algorithm has certain prediction precision and can effectively predict the accumulated electric energy substitute quantity.
It is important to note that the construction and arrangement of the present application as shown in the various exemplary embodiments is illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters (e.g., temperatures, pressures, etc.), mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in this application. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. Accordingly, all such modifications are intended to be included within the scope of this invention. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present inventions. Therefore, the present invention is not limited to a particular embodiment, but extends to various modifications that nevertheless fall within the scope of the appended claims.
Moreover, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not be described (i.e., those unrelated to the presently contemplated best mode of carrying out the invention, or those unrelated to enabling the invention).
It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.
It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.

Claims (8)

1. A method for predicting electric energy substitution potential based on genetic algorithm and BP neural network combination is characterized in that: the method comprises the following steps:
defining electric energy substitution quantity for describing electric energy substitution potential;
determining relevant factors influencing the electric energy substitution amount, and quantifying the relevant factors influencing the electric energy substitution amount;
determining a BP neural network structure;
optimizing the initial weight and threshold of the artificial neural network through a genetic algorithm;
and predicting the electric energy substitution amount through the trained BP neural network.
2. The method for predicting electric energy substitution potential based on the combination of genetic algorithm and BP neural network as claimed in claim 1, wherein: the electric energy substitution amount is an objective basis for realizing quantitative calculation and analysis of electric energy substitution potential, and is a process of continuously accumulating and advancing, namely historical technical and policy measures and the like still influence the future, so the accumulated electric energy substitution amount of each year is calculated on the basis to quantitatively represent the electric energy substitution process, the actual electric energy consumption in the t year is Ef (t), the total terminal energy consumption is Eq (t), if the energy pattern for the terminal maintains the level of the t year, the proportion of electric energy occupied by the electric energy in the terminal is the same as that in the t year, the electric energy consumption increment in the t +1 year compared with that in the previous year is defined as the electric energy substitution amount in the t +1 year, and specific expressions of the electric energy substitution amount and the accumulated electric energy substitution amount are respectively as follows:
Figure FDA0002388229580000011
E(t)=∑Esub(t)
in the formula: esub(t +1) is the electric energy replacement amount in the t +1 th year; ef(t +1) is the actual power consumption in the t +1 th year; eq(t +1) is the total terminal energy consumption in the t +1 th year; e (t) is the accumulated electric energy replacement amount of the t year and is the sum of the electric energy replacement amounts before the t year.
3. The method for predicting electric energy substitution potential based on the combination of genetic algorithm and BP neural network as claimed in claim 1, wherein: the factors influencing the electric energy replacement process are many, and main influencing factors are selected for analysis, namely the four influencing factors of economic development, electric energy replacement technology development, environmental protection and policy guidance, and the specific analysis is as follows:
the economic development factor and the power demand have an inseparable relationship, so that the total value of all production of people is selected to reflect the influence of economic development on electric energy substitution in the electric energy substitution process in China, and the specific expression is as follows:
Figure FDA0002388229580000021
in the formula: gAve(t) represents the total per capita production value of the t year; g (t) represents the total production value of the t year; p (t) represents the total population in the t year.
The progress of the electric energy substitution technology can promote the progress of electric energy substitution development, so the ratio of actual electric energy consumption to theoretical electric energy consumption is selected to measure the development level of the electric energy substitution technology, and the specific expression is as follows:
Figure FDA0002388229580000022
wherein η (t) represents the ratio of actual power consumption to theoretical power consumption in the t-th year, E1(t) represents an actual power consumption amount of the t year; p (t) represents the theoretical power consumption in the t year.
The environmental protection nature mainly includes that sulfur dioxide and powder (cigarette) dirt come from the substituted influence of electric energy, so carry out the analysis through the emission of sulfur dioxide and powder (cigarette) dirt, because the emission of sulfur dioxide and powder (cigarette) dirt is different to the substituted influence of electric energy, so increase the weight coefficient to the emission of sulfur dioxide and powder (cigarette) dirt respectively and carry out the gross quantization, specific expression is:
H(t)=αH1(t)+βH2(t)
wherein H (t) represents the total pollutant emission amount after the quantization in the t year, α represents a weight coefficient of the sulfur dioxide pollutant on the electric energy substitution influence in the quantization process, and H1(t) represents the total amount of sulfur dioxide pollutant discharged from the atmosphere in the t year, β represents a weight coefficient of the influence of the dust pollutant on the replacement of electric energy in the quantification process, H2(t) for year tTotal amount of dust (smoke) pollutant discharged in atmosphere.
The policy-oriented main expression is that the competitiveness of electric energy in a terminal energy market is improved by strengthening electric power construction and subsidy policies and improving the economy of the electric energy, so that the influence of the policy on the electric energy substitution development is expressed by selecting the ratio of the investment of a newly-built energy fixed asset, and the specific expression is as follows:
Figure FDA0002388229580000023
in the formula: m (t) represents the ratio of the investment of the newly built electric fixed assets to the investment of the newly built energy fixed assets in the t year; fe(t) represents the investment of the newly built electric fixed assets in the t year; f (t) represents the investment of the energy fixed assets newly built in the t year.
4. The method for predicting electric energy substitution potential based on the combination of genetic algorithm and BP neural network as claimed in claim 1, wherein: the BP neural network consists of two processes of forward propagation of data flow and backward propagation of error signals, the propagation direction is input layer → hidden layer → output layer during the forward propagation, the state of each layer of neuron only affects the next layer of neuron, if the expected output can not be obtained at the output layer, the backward propagation process of the error signals is turned, through the alternate operation of the two processes, the error function gradient descent strategy is executed in the weight vector space, a group of weight vectors are dynamically and iteratively searched, the network error function reaches the minimum value, thereby completing the information extraction and memory process,
because the unit of the input data is different, the range of some data may be particularly large, resulting in slow convergence of the neural network, long training time, and limited value range of the activation function of the output layer of the neural network, normalization of the data is required, and the data is mapped to the [0,1] interval, where the specific expression is:
Figure FDA0002388229580000031
in the formula: y is data after x normalization; x is the number ofminIs the minimum value of x; x is the number ofmaxPredicting the maximum value of x by using a feedforward three-layer network, wherein the input layer of the network has 4 nodes, the hidden layer of the network has q nodes, the output layer of the network has 1 node, and the weight value between the input layer and the hidden layer is vkiThe weight between the hidden layer and the output layer is wk、bkB are the threshold values of the hidden layer and the output layer respectively, and the transfer function of the hidden layer is f1The transfer function of the output layer is f2
The output specific expression of the hidden node is:
Figure FDA0002388229580000032
the specific expression of the output layer node is as follows:
Figure FDA0002388229580000033
the BP neural network completes the approximate mapping of the 4-dimensional space vector to the 1-dimensional space, and the neural network structure is determined.
5. The method for predicting electric energy substitution potential based on the combination of genetic algorithm and BP neural network as claimed in claim 4, wherein: in order to minimize the error function of the BP neural network, the error function is defined, assuming that the input P sets of training data, since the output layer nodes are 1, ypThat is, the error of the P groups of training data can be obtained by using a mean square error function as the output of the network, and the specific expression is as follows:
Figure FDA0002388229580000034
in the formula, p is the number of training samples;
Figure FDA0002388229580000041
desired output for networkA value; y ispIn order to actually output the value for the network,
adjusting w using accumulated error BP algorithmjkAnd reducing the global error MSE, wherein the specific expression is as follows:
Figure FDA0002388229580000042
wherein η is the learning rate,
and continuously iterating and correcting the weight until the error meets the requirement, namely:
wjk=wjk+Δwjk
6. the method for predicting electric energy substitution potential based on the combination of genetic algorithm and BP neural network as claimed in claim 1, wherein: the BP neural network has low learning speed and convergence speed and is easy to fall into a local minimum value, so that the initial weight and the threshold of the BP neural network are optimized by adopting the genetic algorithm, the optimized BP neural network can better predict function output, the BP neural network is optimized by adopting the genetic algorithm to obtain better initial weight and threshold of the network, the basic idea is to use the initial weight and the threshold of an individual representative network and the prediction error of the BP neural network initialized by individual values as the fitness value of the individual, and the optimal individual, namely the optimal initial weight and the threshold of the BP neural network, is searched by selection, intersection and mutation operations.
7. The method of claim 6, wherein the method for predicting electric energy substitution potential based on the combination of genetic algorithm and BP neural network is characterized in that: coding the weight value from the input layer to the hidden layer, the hidden layer threshold value, the weight value from the hidden layer to the output layer and the output layer threshold value by acquiring the BP neural network structure information, wherein a floating point number coding mode is adopted, and the coding length is as follows:
L=inputnum*hiddennum+hiddennum+hiddennum*outputnum+outputnum
=4q+q+q+1
=6q+1
in the formula: l is the code length; inputnum is the number of neurons in the input layer; hiddennum is the number of hidden layer neurons; output number is the number of output layer neurons,
initializing a group, and adopting the reciprocal of the square sum of the predicted value and the true value as a fitness function, wherein the specific expression is as follows:
Figure FDA0002388229580000043
in the formula: p is the number of training samples;
Figure FDA0002388229580000051
an expected output value for the network; y ispThe actual output value of the network.
8. The method for predicting electric energy substitution potential based on the combination of genetic algorithm and BP neural network as claimed in claim 1, wherein: the method for predicting the electric energy substitution amount through the trained BP neural network mainly comprises the following steps:
quantizing the relevant influence factors predicted in the year, and performing data normalization on the quantized data to obtain data input into the neural network;
inputting the prediction data to the trained BP neural network to obtain an output prediction value;
and performing data inverse normalization on the output predicted value to obtain the predicted value of the electric energy substitute quantity.
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