CN115544856A - Day-ahead optimized scheduling method for electric heating integrated energy system - Google Patents
Day-ahead optimized scheduling method for electric heating integrated energy system Download PDFInfo
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Abstract
The invention discloses a day-ahead optimized scheduling method for an electric heating comprehensive energy system. The method comprises the following steps: analyzing the characteristics of the wind power output data, and establishing a non-Gaussian distribution model of the uncertainty of the wind power output; training and predicting historical data through a GRU network to obtain a load predicted value of each scheduling period in the day ahead; establishing a unit model of the electric heating comprehensive energy system; based on uncertainty of wind power output in a scene tree structure description system, according to a load predicted value in the day ahead and a system unit model, a random model prediction control method is used for obtaining day-ahead scheduling parameter control quantity of the electric heating comprehensive energy system; and outputting the control quantity of the day-ahead scheduling parameters to a power supply and heat supply unit for regulation and control. The multi-time scale optimization scheduling method provided by the invention performs characteristic analysis on wind power output data, predicts the load, performs optimization scheduling on the electric heating comprehensive energy system in the future, saves the operation cost of the system, and ensures the stability and robustness of the system.
Description
Technical Field
The invention relates to the field of comprehensive regulation and control of an electric power system and a thermodynamic system, in particular to a day-ahead optimal scheduling method of an electric heating comprehensive energy system.
Background
The electric heating integrated energy system combines an electric power system and a thermodynamic system, meets the requirements of heat load and electric load in the system by coordinately adjusting the output of the thermodynamic system and the electric power system, and is widely applied to the electric heating integrated energy system based on a cogeneration unit especially in the northern area with heating requirement. However, the operation mode of the thermoelectric generator set in the electric heating comprehensive energy system for fixing the power by heat limits the internet access space of renewable energy wind power generation, and the coordination and optimization scheduling of the electric heating comprehensive energy system faces new challenges along with the improvement of the grid-connected proportion of the wind power output.
The wind power output has uncertainty such as randomness, intermittence and volatility, which brings challenges to the safety, reliability and operation of the electric heating comprehensive energy system. The coordinated optimization scheduling of the electric heating comprehensive energy system can be divided into day-ahead scheduling according to the scheduling time scale, a reasonable scheduling optimization scheme can cope with system uncertainty, the operation reliability and safety of the electric heating comprehensive energy system are guaranteed, and the gas consumption and the coal consumption of the system are reduced.
In recent years, advanced optimal scheduling techniques have improved the responsiveness and performance of the system, but these methods do not fully consider the uncertainty factors in the system, and cannot achieve optimal scheduling of the system. The day-ahead scheduling mode can make reasonable scheduling arrangement in advance, but cannot deal with real-time uncertainty of the system.
Disclosure of Invention
In order to solve the influence of uncertainty of wind power output on an electric heating comprehensive energy system, the invention provides an optimal scheduling method for day-ahead scheduling.
A day-ahead optimization scheduling method for an electric heating integrated energy system comprises the following steps:
step 1: performing characteristic analysis on historical wind power output data, and establishing a probability distribution model for describing the uncertainty of the wind power output;
step 2: predicting the load by utilizing a GRU network according to the environmental factors of the wind power output and historical data to obtain a load predicted value of each scheduling time interval in the day ahead;
and step 3: establishing a unit model of each component in the electric heating comprehensive energy system;
and 4, step 4: according to the wind power output uncertainty model in the step 1, describing uncertainty of wind power output in the system based on a scene tree structure; according to the load predicted value of each scheduling time interval in the day before obtained in the step 2 and the system model established in the step 3, solving by using a random model prediction control method to obtain the day-ahead scheduling parameter control quantity of the electric heating integrated energy system;
and 5: and outputting the control quantity of the day-ahead scheduling parameters to a power supply unit, a heat supply unit and an electric heating boiler, and regulating and controlling the power output of the unit at each scheduling time interval and the power input of the electric heating boiler to realize the optimal scheduling of the system.
The step 1) is specifically as follows:
the method comprises the steps of cleaning and analyzing characteristics of historical output data of wind power generation to obtain probability distribution characteristics of wind power output data, establishing a non-Gaussian distribution model of wind power output, and obtaining a probability density function of the wind power distribution model in an original non-Gaussian form.
The step 2) is specifically as follows:
and training and predicting the load by utilizing the established prediction network structure according to the environmental factors influencing the wind power output and the historical load data, and outputting the load demand predicted value at the day before.
The established network structure comprises a CNN layer, a GRU network and an Attention mechanism layer which are connected in sequence; the input of the network structure is wind speed, illumination, temperature and load at a sampling moment, and the output of the Attention layer is a load predicted value of each scheduling period in the day ahead: electric load for k-time systemThermal load power
The electric heating comprehensive energy system comprises an electric power system and a thermodynamic system, the electric power system and the thermodynamic system are coupled through a thermoelectric unit, the thermodynamic system provides heat energy for a heat load through the thermoelectric unit and an electric heating boiler, the electric power system provides electric energy for the heat load through the thermoelectric unit, a conventional generator set and a fan, meanwhile, the system further comprises an energy storage system used for storing and releasing the electric energy of the electric heating comprehensive energy system, and unit models of all parts are respectively established.
The unit model of each part comprises:
(1) Thermoelectric unit operation model
Wherein the content of the first and second substances,the generated power at the k moment of the ith set of CHP unit, eta GT For the comprehensive conversion efficiency of the gas turbine in the CHP unit, H ng Is a high heating value natural gas, and the natural gas has high heating value,for the natural gas flow consumed by the ith set of CHP unit k at the moment, in the constant heat/power ratio mode, the heat power of the CHP unit is related to the output electric power of the unit, and can be expressed as follows:
wherein the content of the first and second substances,the heat power of the CHP unit at the moment k; c. C CHP The heat-electricity ratio of the CHP unit;
(2) Thermal operation model of electric heating boiler
Wherein, the first and the second end of the pipe are connected with each other,heating power of ith electric boiler at time k, eta EB In order to improve the electric heat conversion efficiency of the electric boiler,the electricity power is used for the ith electric boiler at the moment k;
(3) Conventional generator set operation model
Wherein the content of the first and second substances,representing the coal consumption of the ith conventional generating set at the moment k and representing the generated power of the conventional generating set, a i ,b i ,c i Representing coefficients related to the operation of the unit;
(4) Energy storage system model
In the dispatching of the electric heating comprehensive energy system, the energy storage system has the characteristic of high response speed, can compensate the power balance deviation of the system under the interference, and is an important component in the system; the energy storage system charging and discharging power model can be described as follows:
wherein the content of the first and second substances,the capacity of the ith energy storage system at the moment k is shown, and delta T represents a unit scheduling time interval;charging and discharging power for the energy storage system at k moment; eta c And η d Respectively charging and discharging efficiencies of the energy storage system;the charge-discharge state of the energy storage system at k moment, when the energy storage system is chargedDuring discharge
(5) Plant operating constraints
The constraint of the upper and lower power limits of each unit device in the electric heating comprehensive energy system is required to be met at each operating moment, and the constraint is expressed as follows:
wherein the content of the first and second substances, respectively representing the upper and lower limit values of the operating power of the ith conventional generator set, the CHP generator set, the wind turbine generator set, the energy storage equipment and the electric boiler;andrespectively is the minimum value and the maximum value of the charge-discharge capacity of the energy storage system; n is a radical of G ,N CHP ,N WT ,N E ,N EB The number of the corresponding unit equipment in the system is set;
(6) Power change rate constraints
The control operation of each unit equipment in the system is required to be satisfied within a safety range, and is defined The control power variation of the conventional generator set, the CHP generator set, the wind turbine generator set and the electric boiler in a unit scheduling period delta T is used for regulating and controlling the power output of the generator set in each scheduling period, and the following constraints are required to be met:
wherein the content of the first and second substances,andandandandare respectively an ith conventional generatorThe upper and lower limit values of the power change of the group, the CHP unit, the wind turbine generator and the electric boiler in a unit scheduling period delta T;
(7) Electric and thermal power balance constraint
The electric heating comprehensive energy system needs to meet the electric load and heat load requirements of users by adjusting the parameter control quantity of each unit device in the operation process. The power balance constraint of the system is:
wherein the content of the first and second substances,andthe power generation power of the conventional generator set and the power generation power of the wind generating set at the moment k are respectively;the system power load is used at the moment k,the thermal load power at time k of the system.
The wind power output uncertainty model according to the step 1) is used for describing uncertainty of wind power output in the system based on a scene tree structure; the method comprises the following steps:
establishing a scene tree structure-based wind power change explicit expression structure according to the non-Gaussian distribution model of the wind power output in the step 1) to obtain the probability omega of different wind power scenes s s 。
The method for solving and obtaining the parameter control quantity of the day-ahead scheduling of the electric heating integrated energy system by using a random model predictive control method according to the load predicted value of each scheduling time interval in the day-ahead obtained in the step 2) and the system model established in the step 3) comprises the following steps:
a. establishing an optimization problem model based on a model predictive control MPC method according to models of all units and equipment of the electric heating comprehensive energy system;
selecting the real-time power of each unit device in the k-time system and the capacity of the energy storage system as a system state variable x k Selecting the variable quantity of each equipment power in unit scheduling period delta T as the system optimization control parameter variable u k Respectively defined as:
in the operation process of the electric heating comprehensive energy scheduling system, under the condition of meeting the real-time electricity and heat load requirements of users and the self operation constraint conditions of each unit and equipment in the system, the aim of improving wind power consumption and reducing comprehensive operation cost is fulfilled, and the generation and heating power of each equipment participating in the adjustment of supply and demand balance is optimized;
gas consumption of power generation and heating equipment of electric heating comprehensive energy scheduling systemAnd the electricity purchase cost of the electric equipmentRespectively expressed as:
where k denotes the current time, R ng The gas purchase price of the system is represented,purchasing electricity price for the system; running performance index l of system at moment k k Can be expressed as:
the objective function is as follows:
wherein J represents an objective function, N p The time domain is predicted for the system. Wherein:
Q=diag{c 1 ,c 2 ,...,c NG ,0,...,0}
the four constraints are as follows:
s.t.x k+j+1|k =A·x k+j|k +B·u k+j|k
p x ·x k+j|k ≤q x
p u ·u k+j|k ≤q u
wherein the first constraint condition is a state space equation of the electric heating comprehensive energy system, wherein
N A =N G +N CHP +N EB +N E
N B =N G +N CHP +N EB
Wherein the content of the first and second substances,charging or discharging efficiency of the ith set of energy storage system at the moment k;
the second constraint is the adaptation of the electrical-thermal equilibrium constraint equations in the system model, where:
C=[d P ,d Q ] T ,D=[1,0] T
wherein the content of the first and second substances,is a predicted value of the electric heating load at each moment in the day, w k+j|k Predicting the wind power generation power value in the time domain;
the third constraint condition and the fourth constraint condition describe the constraint of the upper and lower power limits of the unit equipment and the constraint of the variable quantity of the control power in the scheduling period delta T, wherein:
b. establishing a random model predictive control model (SMPC) based on the scene tree model, and solving to obtain a day-ahead scheduling scheme of the electric heating comprehensive energy system; the method comprises the following steps:
at the moment k, the control variable of the stochastic economic model predictive control on the prediction time domain can be expressed as:
wherein N is s The total number of the branches of the scene tree, namely the total number of the optimized paths of the system; s represents an s-th scene tree structure branch; j denotes the time j-th in the prediction time domain. The corresponding predicted state variables are:
further improving the objective function J based on the scene tree to obtain N s Probability omega combining different wind power scenarios s And calculating the weighted sum of the system operation performance indexes under all probability situations
Wherein the content of the first and second substances,weighted sum, omega, of day-ahead scheduling operation indices for an electric heating integrated energy system s Representing the probability of occurrence under different wind power scenarios s obtained by the scenario tree,indicating the performance index of the correction after introducing the relaxation variable,represents an introduced relaxation variable;
the corresponding constraint conditions are:
solving the random model predictive control problem to obtain the unit parameter control quantity of the electric heating comprehensive energy system at the moment k under the day-ahead optimized scheduling strategy of the system operation: the control power variation of the conventional generator set, the CHP set and the electric boiler in a unit scheduling period delta T is as follows:and the charging and discharging power of the energy storage system
A day-ahead optimized dispatching system of an electric heating comprehensive energy system comprises an electric power system, a thermodynamic system, an energy storage system and an upper computer controller; the thermodynamic system comprises a thermoelectric unit and an electric heating boiler and is used for generating electric heating energy under the instruction of the controller; the power system comprises a thermoelectric generating set, a conventional generating set and a fan, and the energy storage system is used for storing and releasing electric energy of the power system; the upper computer controller comprises a processor and a memory, wherein the memory stores programs, the processor loads the programs to execute the steps of the method, and the control power variation of the conventional generator set, the CHP set and the electric boiler in a unit scheduling period delta T is obtained:and charging and discharging power of energy storage systemAnd outputting the data to each unit on site to realize optimized scheduling.
The invention has the following effects and advantages:
1. the invention provides the optimized scheduling of the electric heating comprehensive energy system from a plurality of time scales, and the air abandoning rate of the system and the gas consumption and coal consumption of the system are reduced.
2. The established random model prediction control method utilizes the scene tree structure to express the uncertainty of the wind power output of the system, fully considers the random variation condition of the wind power, reduces the interference of the wind power randomness in the system optimization scheduling, and improves the system robustness.
3. The model and the method established by the invention can be used for scheduling optimization of the electric heating comprehensive energy system, and take the error of the prediction of the wind power output at the present into consideration, thereby laying a foundation for wind power consumption and reliable operation of the system.
Drawings
FIG. 1 is a flow chart of the method of the present invention;
FIG. 2 is a block diagram of a GRU predictive network of the method of the present invention;
FIG. 3 is an electric heat integrated energy system configuration of the method of the present invention;
FIG. 4 is a scene tree structure of the method of the present invention;
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 to enable one skilled in the art to better understand the present invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather should be construed as modified in the spirit and scope of the present invention as set forth in the appended claims.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
As shown in fig. 1, the method for optimizing and scheduling the electric heating integrated energy system in the day ahead comprises the following steps:
1) Carrying out characteristic analysis on the wind power output data to obtain the distribution characteristics of the data, and establishing a probability distribution model of the uncertainty of the wind power output;
2) According to the environmental factors of the wind power output and the historical load data, predicting the load by using a GRU network to obtain a load predicted value of each scheduling time period in the day before the wind power output;
3) Establishing a unit model of each component in the electric heating comprehensive energy system;
4) According to the wind power output uncertainty model in the step 1), describing uncertainty of wind power output in the system based on a scene tree structure, obtaining a day-ahead scheduling scheme of the electric heating comprehensive energy system by using a random model prediction control method according to the load prediction value of each scheduling time period in the day-ahead obtained in the step 2) and the system unit model established in the step 3);
5) And 5: and outputting the control quantity of the day-ahead scheduling parameters to a power supply unit, a heat supply unit and an electric heating boiler, and regulating and controlling the power output of the unit in each scheduling period to realize optimized scheduling. The unit parameter control quantity under the day-ahead optimized scheduling strategy is as follows: the control power variation of the conventional generator set, the CHP set and the electric boiler in a unit scheduling period delta T is as follows: and charging and discharging power of energy storage system
In the step 1), the data set adopted by the invention is derived from CAISO, the data set comprises 2019 wind power output data, load, real-time electricity price data and the like, and the sampling time interval is 1 hour. The method comprises the steps of firstly cleaning and preprocessing historical wind power output data, completing missing data in an original data file by adopting an interpolation method, and sequencing the data according to sampling time. And then, carrying out feature analysis on the wind power output data by using a scimit-spare toolkit based on a python programming language.
As can be seen from a scatter diagram of the wind power output data, the wind power output data has extremely strong uncertainty, and the distribution of the wind power output data does not accord with standard Gaussian distribution, so an improved wind power non-Gaussian probability transformation model is provided, wind power sequences which do not meet the standard Gaussian distribution are transformed into new sequences which meet the standard Gaussian distribution, and the transformation model is expressed as follows:
wherein the non-linear transformation function f i (. The ith wind generating set history non-Gaussian distribution sequence P WT,i Transforming into a sequence of Gaussian distributionsψ 1 ,ψ 2 ,ψ 3 For transforming the parameters, and psi 1 ,ψ 2 Is more than or equal to 0. Thus, the post-sequence is transformedCan be expressed as the following gaussian distribution model:
the probability density function of the wind power distribution model in the original non-gaussian form calculated according to the formula above can be expressed as:
because the actual wind power values are all larger than or equal to zero, the nonlinear transformation function f i And monotonous on a definition domain, namely, the inverse function has a numerical solution in a feasible domain, and for each Gaussian distribution random value which accords with the formula, a value which accords with the original distribution of the wind power sequence can be found to correspond to the value.
In the step 2), the GRU is a special RNN, which has a structure similar to the LSTM, and referring to fig. 2, the GRU replaces an input gate and a forgetting gate of the LSTM with an update gate, and accesses a reset gate to determine how much the neuron hidden layer output at the previous time is reset. The reduction of gate units allows GRUs to have fewer training sessions, increasing the speed of training, and also allowing them to be more predictive than LSTM.
In order to improve the prediction accuracy, a CNN convolutional network is added before GRU for processing historical data, and an Attention mechanism is added after GRU, so that the learning capability of the GRU network on information correlation is further improved, and the prediction accuracy is improved.
The data set for GRU training is 8760 lines of environmental factors and load data related to wind power output in 2019 all the year around, and each line represents a wind speed, illumination, temperature and load demand sample at one sampling moment. The data from 20 days before each month were selected as the training set for 5760 lines and the data from the remaining days as the test set for 3000 lines. Each sample contained historical wind speed, light and temperature data for the past 24 hours, for 75 columns.
Firstly, an input layer is connected to a CNN layer, and data characteristics are calculated:
y k =f(x k-1 u k-1 +x k u k +x k+1 u k+1 +b k )
in the formula y k Output of a characteristic value representing time k, x k The data sample value representing the k moment is a four-dimensional vector which represents the wind speed, the illumination, the temperature and the load at a sampling moment, u k Representing the convolution kernel at time k, b k Is a constant.
Then, the output of the CNN layer is used as the input of the GRU network, and the operation process of each hidden layer in the network is as follows:
r k =σ(W r *h k-1 +U r *y k +b r )
z k =σ(W z *h k-1 +U z *y k +b z )
where σ denotes the activation function, b r And b z Respectively represent reset gates r k And an update gate z k Bias constant of (W) r ,U r ,W z ,U z Respectively representing parameters of the GRU network to be trained. Inputting the characteristic data y of the current moment k By resetting the gate r k And an update gate z k Respectively determining the hidden layer state h of the previous time k-1 How much information is forgotten and how much information is transferred to the hidden layer h at the current moment k In (1).
After obtaining the gating information, the gating information r is reset k And the previous time hidden layer state h k-1 Hadamard product is performed to determine the hidden layer h at the previous time k-1 How much information will be forgotten, the obtained reset information and the input y at the current moment k The binding is put into the activation function tanh.
h′ k =tanh(W c *(r k *h k-1 )+U c *y k +b c )
Wherein tan h is the activation function, b c Representing the bias constant of the forgetting gate. W c ,U c A parameter matrix trained for the network.
Finally, the door z is updated according to the previous obtained t Determining the hidden layer h at the current time t 。
h k =(1-z t )*h k-1 +z t *h′ k
An Attention mechanism is accessed behind a GRU network layer and is used for learning output data of the GRU network. And the output of the Attention layer is the final load predicted value of each scheduling period in the day ahead.
Compared with the prediction results of the GRU network and the LSTM network, the prediction precision is improved by 14.25%.
In the step 3), the electric heating comprehensive energy system comprises a thermal power system and an electric power system, the thermal power system provides heat energy for a thermal load through a thermoelectric unit and an electric heating boiler, the electric power system provides electric energy for the electric load and the electric heating boiler through the thermoelectric unit, the thermal power system is coupled with the electric power system through the thermoelectric unit, meanwhile, the system also comprises an energy storage system used for guaranteeing the supply and demand balance of the electric power system, and unit models of all parts are as follows. The structure of the electric heating comprehensive energy system is shown in the attached figure 3.
(1) Thermoelectric unit operation model
Wherein the content of the first and second substances,the generated power at k moment of the ith set of CHP unit is eta GT For the comprehensive conversion efficiency of the gas turbine in the CHP unit, H ng Is a high heating value natural gas, and has high heat value,for the natural gas flow consumed by the ith set of CHP unit k at the moment, in the constant heat/power ratio mode, the heat power of the CHP unit is related to the output electric power of the unit, and can be expressed as follows:
wherein the content of the first and second substances,the heat power of the CHP unit at the moment k; c. C CHP The heat-electricity ratio of the CHP unit.
Wherein the content of the first and second substances,for electric boilers at kThermal power of etching, eta EB In order to improve the electric heat conversion efficiency of the electric boiler,and the electric power is used for the ith electric boiler at the moment k.
Wherein the content of the first and second substances,representing the coal consumption of the ith conventional generator set at the moment k, and the coefficient a i ,b i ,c i Representing parameters related to the operation of the unit.
(4) Energy storage system model
In the dispatching of the electric heating comprehensive energy system, the power balance deviation of the system under the interference can be compensated by utilizing the characteristic of high response speed of the energy storage system, and the electric heating comprehensive energy system is an important component in the system. The energy storage system charge-discharge power model can be described as:
wherein the content of the first and second substances,the capacity of the ith energy storage system at the moment k;charging and discharging power for the energy storage system at k moment; eta c And η d Respectively charging and discharging efficiencies of the energy storage system;for storing energyThe charge-discharge state of the system at the k moment and the charge of the energy storage systemDuring discharge
(5) Plant operating constraints
The constraint of the upper and lower power limits of each unit device in the electric heating comprehensive energy system is required to be met at each operating moment, and the constraint is expressed as follows:
wherein the content of the first and second substances, respectively represents the ith conventional generator set, the CHP generator set, the wind turbine generator set,The upper and lower limit values of the operating power of the energy storage equipment and the electric boiler;andthe minimum value and the maximum value of the charge-discharge capacity of the energy storage system are respectively.
(6) Power rate of change constraint
The control operation of each unit equipment in the system is required to be satisfied within a safety range, and is defined The power changes of a conventional generator set, a CHP generator set, a wind turbine generator set and an electric boiler in a unit scheduling period T respectively need to satisfy the following constraints:
wherein the content of the first and second substances,andandandandthe power change upper and lower limit values of the ith conventional generator set, the CHP generator set, the wind turbine generator set and the electric boiler in the unit scheduling period delta T are respectively.
(7) Constraint of balance of electric and thermal power
The electric heating comprehensive energy system needs to meet the electric load and heat load requirements of users by adjusting the parameter control quantity of each unit device in the operation process. The power balance constraint of the system is:
wherein the content of the first and second substances,andthe power generation power of the conventional generator set and the power generation power of the wind generating set at the moment k are respectively;the system power load is used at the moment k; n is a radical of G ,N CHP ,N WT ,N E ,N EB The number of the corresponding unit equipment in the system.The thermal load power at time k of the system.
In the step 4), the scene tree structure is used for describing the random variation condition of the wind power, the scene tree branch is selected based on the wind power output transformation model established in the step 1) to more accurately describe the wind power variation characteristic, and then the model prediction control method is used for solving, so that the uncertainty degree that the control quantity output of the system at the future moment depends on the wind power output at the previous moment is represented, and the method is a closed-loop robust control strategy.
Referring to FIG. 3, state x at time k of the system k Random quantity of different wind powerUnder the action of (1), n scene tree branches are generated, corresponding to n different operation states of the system at the moment of (k + 1)Similarly, the state of the scene tree at time k +1 There are also n branches corresponding to the state of the system at time k +1Different operation states ofThe system has n from k to k +2 2 Branches, and so on. In order to prevent the calculation amount from exponentially increasing due to excessive situations, a suitable robust time domain N is selected r ≤N P And the branch number n of a single node of the scene tree, and the uncertainty variable is kept unchanged after the robust time domain, so that the closed-loop performance is ensured, and meanwhile, the calculation load is reduced.
Although the scenario tree structure in fig. 3 cannot represent all possibilities of wind power change, a method for effectively selecting branch scenarios of each node is designed according to historical wind power information, and uncertain dynamic change conditions of a system at future time can be represented better. Because the actual wind power output sequence does not meet the standard Gaussian distribution, and the modeling can not be carried out by using a known distribution. Therefore, an improved wind power non-gaussian probability transformation model is proposed:
selecting the real-time power of each unit device in the k-time system and the capacity of the energy storage system as a system state variable x k Selecting the variable quantity of each device power in unit scheduling period delta T as the optimized control parameter variable u of the system k Respectively defined as:
in the operation process of the electric heating comprehensive energy scheduling system, under the condition of meeting the real-time electricity and heat load requirements of users and the self operation constraint conditions of each unit and equipment in the system, the electric heating comprehensive energy scheduling system aims to improve wind power consumption and reduce comprehensive operation cost, and optimizes the participation of each equipment in the adjustment of power generation and heating power of supply and demand balance.
Gas consumption of power generation and heating equipment of electric heating comprehensive energy scheduling systemAnd the electricity purchase cost of the electric equipmentRespectively expressed as:
where k denotes the current time, R ng The gas purchase price of the system is represented,purchasing electricity price for the system; running performance index l of system at moment k k Can be expressed as:
the objective function is as follows:
wherein J represents an objective function, N p The time domain is predicted for the system. Wherein:
the four constraints are as follows:
s.t.x k+j+1|k =A·x k+j|k +B·u k+j|k
p x ·x k+j|k ≤q x
p u ·u k+j|k ≤q u
wherein, the first constraint condition is a state space equation of the electric heating comprehensive energy system, wherein:
N A =N G +N CHP +N EB +N E
N B =N G +N CHP +N EB
wherein the content of the first and second substances,and charging or discharging efficiency of the ith set of energy storage system k at the moment.
The second constraint is the system's electrical-thermal equilibrium equation, where:
C=[d P ,d Q ] T ,D=[1,0] T
wherein the content of the first and second substances,is a predicted value of the electric heating load at each moment in the day k+j|k To predict the wind power generation power value in the time domain.
The third and fourth constraint conditions are the rewriting of the power upper and lower limit constraint of the unit equipment and the power variation constraint in the scheduling period delta T, wherein:
b. obtaining scenes under different wind power groups based on a scene tree model, establishing a random model predictive control model (SMPC), and solving to obtain a day-ahead scheduling scheme of the electric heating integrated energy system; the method comprises the following steps:
at the moment k, the control variable of the stochastic economic model predictive control on the prediction time domain can be expressed as:
wherein N is s The total number of the branches of the scene tree, namely the total number of the optimized paths of the system; s represents an s-th scene tree structure branch; j denotes the time j-th in the prediction time domain. The corresponding predicted state variables are:
target function J based on scene treeFurther improvement, to obtain N s Probability omega combining different wind power scenarios s And calculating the weighted sum of the system operation performance indexes under all probability situations
Wherein the content of the first and second substances,the final output electric heating comprehensive energy system is in N s Weighted summation of performance indicators, omega, under different wind power scenarios s Representing the probability of occurrence under different wind power scenarios s obtained by the scenario tree,the performance index of the correction after the relaxation variable is introduced is shown,represents the introduced relaxation variable, and λ is a penalty factor.
The corresponding constraint conditions are:
the system needs to satisfy constraints under any uncertain situation:
because the system can not accurately predict the size of uncertain variables at future time, corresponding control quantity can not be selected according to the size, and the same control variable u is adopted at each scene tree node k To satisfy the "future invisibility" of the wind speed, i.e. the "immeasurable constraints" of the system:
uncertain variables in FIG. 4For the system in state x k And (4) possible values of n wind power uncertainty variables. The invention sets the same scene branch number at each node in the robust time domain. Selecting a prediction time domain N from 96 sampling points every day P At 96, i.e. scheduled 24 hours (days ago) in advance, each time interval Δ T is 15min. And solving the random model predictive control problem by adopting IPOPT based on CasADi technology to obtain the unit parameter control quantity under the day-ahead optimized scheduling strategy of the electric heating comprehensive energy system when the system operates at the moment k. The hardware environment is Intel Core i5-7400,6G RAM and Matlab2018a.
In conclusion, the invention provides a day-ahead optimization scheduling method for an electric heating integrated energy system, which considers the uncertainty of wind power output and analyzes the historical data of the wind power output to obtain a probability distribution model of the uncertainty of the wind power output; then predicting the load by utilizing the GRU; and then according to the predicted day-ahead load data, a day-ahead scheduling scheme is obtained by using a random prediction control method, and the day-ahead scheduling method can improve the consumption of the wind power output of the renewable energy source and reduce the coal consumption of the system on the premise of ensuring the reliability and the safety of the system.
Although the present invention has been described in detail in the above examples, the scope of application of the present invention is not limited thereto. It will be apparent to those skilled in the art that the system may be scaled and complicated without departing from the scope of the claims.
Claims (9)
1. A day-ahead optimization scheduling method for an electric heating comprehensive energy system is characterized by comprising the following steps:
step 1: performing characteristic analysis on historical wind power output data, and establishing a probability distribution model for describing the uncertainty of the wind power output;
step 2: predicting the load by utilizing a GRU network according to the environmental factors of the wind power output and the historical data to obtain the load predicted value of each scheduling time period in the day ahead;
and step 3: establishing a unit model of each component in the electric heating comprehensive energy system;
and 4, step 4: according to the wind power output uncertainty model in the step 1, describing uncertainty of wind power output in the system based on a scene tree structure; according to the load predicted value of each scheduling time interval in the day before obtained in the step 2 and the system model established in the step 3, solving by using a random model prediction control method to obtain the day-ahead scheduling parameter control quantity of the electric heating integrated energy system;
and 5: and outputting the control quantity of the day-ahead scheduling parameters to a power supply unit, a heat supply unit and an electric heating boiler, and regulating and controlling the power output of the unit at each scheduling time interval and the power input of the electric heating boiler to realize the optimal scheduling of the system.
2. The day-ahead optimization scheduling method for the electric-thermal integrated energy system according to claim 1, wherein the step 1) is specifically as follows:
the method comprises the steps of cleaning and analyzing characteristics of historical output data of wind power generation to obtain probability distribution characteristics of wind power output data, establishing a non-Gaussian distribution model of wind power output, and obtaining a probability density function of the wind power distribution model in an original non-Gaussian form.
3. The day-ahead optimization scheduling method of the electric heating integrated energy system according to claim 1, wherein the step 2) is specifically as follows:
and training and predicting the load by utilizing the established prediction network structure according to the environmental factors influencing the wind power output and the historical load data, and outputting the load demand predicted value at the day before.
4. The electric heating comprehensive energy system day-ahead optimization scheduling method of claim 3, wherein the established network structure comprises a CNN layer, a GRU network and an Attention mechanism layer which are connected in sequence; the input of the network structure is wind speed, illumination, temperature and load at a sampling moment, and the output of the Attention layer is a load predicted value of each scheduling time period in the day ahead: electric load for k-time systemPower of thermal load
5. The day-ahead optimized scheduling method of an electrothermal integrated energy system according to claim 1, wherein the electrothermal integrated energy system comprises an electric power system and a thermal system, the electric power system and the thermal system are coupled through a thermoelectric unit, the thermal system provides heat energy for a thermal load through the thermoelectric unit and an electric heating boiler, the electric power system provides electric energy for the electrical load through the thermoelectric unit, a conventional generator set and a fan, and the system further comprises an energy storage system for storing and releasing the electric energy of the electrothermal integrated energy system to respectively establish unit models of each part.
6. The electric heating integrated energy system day-ahead optimization scheduling method of claim 1, wherein the unit model of each part comprises:
(1) Thermoelectric unit operation model
Wherein the content of the first and second substances,the generated power at the k moment of the ith set of CHP unit, eta GT For the comprehensive conversion efficiency of the gas turbine in the CHP unit, H ng Is a high heating value natural gas, and the natural gas has high heating value,for the natural gas flow consumed by the ith set of CHP unit k at the moment, in the constant heat/power ratio mode, the heat power of the CHP unit is related to the output electric power of the unit, and can be expressed as follows:
wherein, the first and the second end of the pipe are connected with each other,the heat power of the CHP unit at the moment k; c. C CHP The heat-electricity ratio of the CHP unit;
(2) Thermal operation model of electric heating boiler
Wherein the content of the first and second substances,heating power of ith electric boiler at time k, eta EB In order to improve the electric heat conversion efficiency of the electric boiler,the electricity power is used for the ith electric boiler at the moment k;
(3) Conventional generator set operation model
Wherein the content of the first and second substances,represents the coal consumption of the ith conventional generating set at the moment k, represents the generating power of the conventional generating set, and a i ,b i ,c i Representing coefficients related to the operation of the unit;
(4) Energy storage system model
In the dispatching of the electric heating comprehensive energy system, the energy storage system has the characteristic of high response speed, can compensate the power balance deviation of the system under the interference, and is an important component in the system; the energy storage system charging and discharging power model can be described as follows:
wherein the content of the first and second substances,the capacity of the ith energy storage system at the moment k is shown, and delta T represents a unit scheduling time interval;charging and discharging power for the energy storage system at k moment; eta c And η d Respectively charging and discharging efficiencies of the energy storage system;the energy storage system is in a k-time charging and discharging state when being chargedDuring discharge
(5) Plant operating constraints
The constraint of the upper and lower power limits of each unit device in the electric heating comprehensive energy system is required to be met at each operating moment, and the constraint is expressed as follows:
wherein the content of the first and second substances, respectively representing the upper and lower limit values of the operating power of the ith conventional generator set, the CHP generator set, the wind turbine generator set, the energy storage equipment and the electric boiler;andrespectively is the minimum value and the maximum value of the charge-discharge capacity of the energy storage system; n is a radical of G ,N CHP ,N WT ,N E ,N EB The number of the corresponding unit equipment in the system is set;
(6) Power change rate constraints
The control operation of each unit equipment in the system needs to be satisfied within a safety range, and the information is determined The control power variation of the conventional generator set, the CHP generator set, the wind turbine generator set and the electric boiler in a unit scheduling period delta T is used for regulating and controlling the power output of the generator set in each scheduling period, and the following constraints are required to be met:
wherein the content of the first and second substances,andandandandthe power change upper and lower limit values of the ith conventional generator set, the CHP generator set, the wind turbine generator set and the electric boiler in a unit scheduling period delta T are respectively set;
(7) Electric and thermal power balance constraint
The electric heating comprehensive energy system needs to meet the electric load and heat load requirements of users by adjusting the parameter control quantity of each unit device in the operation process. The power balance constraint of the system is:
7. The day-ahead optimized dispatching method for the electric-thermal integrated energy system according to claim 1, characterized in that according to the wind-electricity output uncertainty model of step 1), the uncertainty of wind-electricity output in the system is described based on a scenario tree structure; the method comprises the following steps:
establishing a scene tree structure-based wind power change explicit expression structure according to the non-Gaussian distribution model of the wind power output in the step 1) to obtain the probability omega of different wind power scenes s s 。
8. The method for optimizing and scheduling an electric heating integrated energy system in the day-ahead according to claim 1, wherein the method for solving and obtaining the parameter control quantity of the electric heating integrated energy system in the day-ahead scheduling by using a random model prediction control method according to the load prediction value of each scheduling time interval in the day-ahead obtained in the step 2) and the system model established in the step 3) comprises the following steps:
a. establishing an optimization problem model based on a model predictive control MPC method according to models of all units and equipment of the electric heating comprehensive energy system;
selecting the real-time power of each unit device in the k-time system and the capacity of the energy storage system as a system state variable x k Selecting the variable quantity of each device power in unit scheduling period delta T as the optimized control parameter variable u of the system k Respectively defined as:
in the operation process of the electric heating comprehensive energy scheduling system, under the condition of meeting the real-time electricity and heat load requirements of users and self operation constraint conditions of units and equipment in the system, the electric heating comprehensive energy scheduling system aims at improving wind power consumption and reducing comprehensive operation cost, and optimizes the participation of the equipment in the adjustment of power generation and heating power of supply and demand balance;
gas consumption of power generation and heating equipment of electric heating comprehensive energy scheduling systemAnd the electricity purchase cost of the electric equipmentRespectively expressed as:
wherein k represents the current time, R ng The gas purchase price of the system is represented,purchasing electricity price for the system; running performance index l of system at moment k k Can be expressed as:
the objective function is as follows:
wherein J represents an objective function, N p The time domain is predicted for the system. Wherein:
the four constraints are as follows:
s.t.x k+j+1|k =A·x k+j|k +B·u k+j|k
p x ·x k+j|k ≤q x
p u ·u k+j|k ≤q u
wherein, the first constraint condition is the state space equation of the electric heating comprehensive energy system, wherein:
N A =N G +N CHP +N EB +N E
N B =N G +N CHP +N EB
wherein the content of the first and second substances,charging or discharging efficiency of the ith set of energy storage system at the moment k;
the second constraint is the adaptation of the electrical-thermal equilibrium constraint equations in the system model, where:
C=[d P ,d Q ] T ,D=[1,0] T
wherein the content of the first and second substances,is a predicted value of the electric heating load at each moment in the day, w k+j|k Predicting the wind power generation power value in the time domain;
the third constraint condition and the fourth constraint condition describe the constraint of the upper and lower power limits of the unit equipment and the constraint of the variable quantity of the control power in the scheduling period delta T, wherein:
b. establishing a random model predictive control model (SMPC) based on the scene tree model, and solving to obtain a day-ahead scheduling scheme of the electric heating comprehensive energy system; the method comprises the following steps:
at the moment k, the control variable of the stochastic economic model predictive control on the prediction time domain can be expressed as:
wherein, N s The total number of the branches of the scene tree, namely the total number of the optimized paths of the system; s represents an s-th scene tree structure branch; j denotes the time j-th in the prediction time domain. The corresponding predicted state variables are:
further improving the objective function J based on the scene tree to obtain N s Probability omega combining different wind power scenarios s And calculating the weighted sum of the system operation performance indexes under all probability situations
Wherein the content of the first and second substances,weighted sum, omega, of day-ahead scheduling operation indexes for an electric heating integrated energy system s Representing the probability of occurrence under different wind power scenarios s obtained by the scenario tree,the performance index of the correction after the relaxation variable is introduced is shown,represents the introduced relaxation variables;
the corresponding constraint conditions are:
solving the random model predictive control problem to obtain the unit parameter control quantity under the day-ahead optimized scheduling strategy of the electric heating integrated energy system at the moment k by the system operation: the control power variation of the conventional generator set, the CHP set and the electric boiler in a unit scheduling period delta T is as follows:and the charging and discharging power of the energy storage system
9. A day-ahead optimized dispatching system of an electric heating comprehensive energy system is characterized by comprising an electric power system, a thermodynamic system, an energy storage system and an upper computer controller; the thermodynamic system comprises a thermoelectric unit and an electric heating boiler and is used for generating electric heating energy under the instruction of the controller; the power system comprises a thermoelectric generating set, a conventional generating set and a fan, and the energy storage system is used for storing and releasing electric energy of the power system; the upper computer controller comprises a processor and a memory, wherein programs are stored in the memory, the processor loads the programs to execute the method steps according to any one of claims 1 to 8, and the control power variation of a conventional generator set, a CHP (combined cycle Power) set and an electric boiler in a unit scheduling period delta T is acquired:and charging and discharging power of energy storage systemAnd outputting the data to each unit on site to realize optimized scheduling.
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