CN113379565A - Comprehensive energy system optimization scheduling method based on distributed robust optimization method - Google Patents
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Abstract
The invention discloses a comprehensive energy system optimization scheduling method based on a distributed robust optimization method, which is characterized in that comprehensive demand response and heat supply network and air supply network pipeline energy storage are cooperatively modeled into virtual energy storage, so that the scheduling flexibility of a comprehensive energy system can be improved, and the uncertainty of the distributed renewable power output in the comprehensive energy system is processed by using the distributed robust optimization method based on Wassertein distance. The comprehensive energy system distribution robust optimization scheduling scheme obtained by the method has better economy and robustness, and the economy and the robustness of the comprehensive energy system distribution robust optimization scheduling scheme can be flexibly adjusted by changing the value of the confidence level and the number of historical samples of the output prediction error of the distributed renewable power supply.
Description
The technical field is as follows:
the invention relates to the field of power systems, in particular to a comprehensive energy system optimization scheduling method based on a distributed robust optimization method.
Background art:
in the context of energy internet, Integrated Energy Systems (IES) have a multi-energy complementary characteristic, which can improve energy utilization efficiency, and the optimal scheduling thereof has become a research hotspot in recent years.
The uncertainty in the output of the distributed renewable power source may affect the economics and stability of the integrated energy system scheduling strategy. Common methods of dealing with distributed renewable power output uncertainty are random planning methods and robust optimization methods. However, the solution result of the stochastic programming method is too optimistic and the solution time is long, while the solution result of the robust optimization method is too conservative. Under the background, the distributed robust optimization method establishes a fuzzy set containing all possible probability distributions based on statistical information of random variables, and can overcome the defects of a random planning and robust optimization method, so that the output uncertainty of the distributed renewable power supply is effectively processed.
In the context of an integrated energy system, the traditional power demand response is expanded to an integrated demand response. In addition, the transmission delay characteristics of the heat supply network and the gas supply network can be modeled as pipeline energy storage. If the comprehensive demand response and the pipeline energy storage are cooperatively modeled into the virtual energy storage, greater flexibility can be provided for multi-energy complementation of the comprehensive energy system, and the economy of optimized scheduling of the comprehensive energy system is further improved.
The invention content is as follows:
the invention mainly solves the technical problem of providing a comprehensive energy system optimization scheduling method based on a distributed robust optimization method by adopting the distributed robust optimization method based on Wasserstein distance.
The technical scheme of the invention is as follows:
a comprehensive energy system optimization scheduling method based on a distributed robust optimization method comprises the following steps:
constructing a virtual energy storage model in the comprehensive energy system;
constructing a fuzzy probability distribution set of the output uncertainty of the distributed renewable power supply in the comprehensive energy system by adopting a Wasserstein distance-based distribution robust optimization method;
and constructing a comprehensive energy system distribution robust optimization scheduling model based on the virtual energy storage model and the fuzzy probability distribution set, and solving a comprehensive energy system optimization scheduling strategy based on a distribution robust optimization method.
Preferably, the virtual stored energy in the integrated energy system comprises integrated demand response, heat supply network pipeline stored energy and gas supply network pipeline stored energy.
Preferably, the constructing a virtual energy storage model in the integrated energy system includes:
firstly, modeling a comprehensive demand response, wherein the comprehensive demand response comprises a load interruption constraint and a load transfer constraint, and the load interruption constraint in the comprehensive demand response is expressed as follows:
in the formula, the superscript t represents the scheduling period t, and the same applies below;is the interrupt power of the electrical load in the integrated demand response;is the maximum proportion of electrical load interruptions;is the electrical load in the integrated energy system;
the load shifting constraint in the integrated demand response is expressed as:
in the formula (I), the compound is shown in the specification,is the transferred power of the electrical load in the integrated demand response;andbinary of shifted out and shifted in electric power respectively in integrated demand responseA coefficient;andrespectively, the removed electric power and the moved electric power in the integrated demand response;is the maximum proportion of electrical load transfer;
and then modeling the energy storage of the pipeline of the heat supply network, and modeling the temperature quasi-dynamics and the heat loss of the pipeline in the heat supply network by adopting a node method, wherein the temperature of the outlet hot water of the water supply pipeline p is expressed as follows:
in the formula (I), the compound is shown in the specification,andthe hot water temperatures at the inlet of the water supply pipe p at times t- (K-1) and t-K, respectively;is the ambient temperature of the heating network; q. q.spAnd q isp+1The mass flow rates of the water supply pipe p and the pipe connected to the outlet of the water supply pipe p, respectively; and τpThe time coefficients of the Kth mass block, the Kth mass block and the mass block at the outlet of the water supply pipeline p are respectively; k is a radical ofpAnd lpThe temperature loss coefficient and the length of the water supply pipe p, respectively;
the heating network pipeline energy storage is expressed as:
in the formula (I), the compound is shown in the specification,the heat supply network pipeline stores energy; c. CwIs the specific heat capacity of water; Δ t is the time interval between two adjacent scheduling times;
modeling the energy storage of the gas supply network pipeline, namely modeling the pipe storage and the average node pressure of the pipeline L in the gas supply network:
in the formula (I), the compound is shown in the specification,andrespectively, the inventory and average node pressure of the pipeline L in the gas supply network; zLIs a pipelineL(ii) a inventory factor of;andthe gas inflow and gas outflow of the pipeline L in the gas supply network are respectively;is a collection of pipes in an air supply network;
the gas supply network pipeline energy storage is expressed as
In the formula (I), the compound is shown in the specification,the gas supply network pipeline stores energy;
and finally, modeling virtual energy storage in the comprehensive energy system, and defining the virtual energy storage of the electric power, the heating power and the natural gas in the comprehensive energy system as the cooperation among the comprehensive demand response, the heat supply network pipeline energy storage and the air supply network pipeline energy storage based on the model of the comprehensive demand response, the heat supply network pipeline energy storage and the air supply network pipeline energy storage:
in the formula (I), the compound is shown in the specification,andrespectively, virtual energy storage for electricity, heat and natural gas.
Preferably, a Wasserstein distance-based distributed robust optimization method is applied to construct a fuzzy probability distribution set of the output uncertainty of the distributed renewable power supply in the comprehensive energy system, and the fuzzy probability distribution set comprises the following steps:
defining the prediction error of the output of the ith distributed renewable power source in the integrated energy system as deltai,δiFor random variables, note deltaiHas a true probability distribution of
Limited historical samples based on prediction errorObtaining an empirical distributionWherein d iskTo representThe Dirac measure of (a);
then by mixingSetting the fuzzy set phi as a center to construct a fuzzy set phi; in the fuzzy set of values phi,andthe distance between the two is measured by Wasserstein distance;
for a given tight support space xi and two probability distributionsAndwasserstein distanceRepresented by the formula:
in the formula (I), the compound is shown in the specification,is to have an empirical distributionA random variable of (a); j is atAnda joint distribution which is an edge distribution;is the distance of two random variables;
wherein
In the formula (I), the compound is shown in the specification,is deltaiThe confidence of (2); η is an auxiliary variable;is the average of historical samples of prediction error; n is a radical ofsamIs the number of historical samples of prediction error;the result is obtained by a binary search method.
Preferably, a distributed robust optimization scheduling model of the integrated energy system is constructed based on the virtual energy storage model and the fuzzy probability distribution set, and an optimized scheduling strategy of the integrated energy system based on a distributed robust optimization method is solved, including:
the power deviation caused by the distributed renewable power source contribution prediction error is distributed to each gas turbine GT, and the actual output power of the ith GT at time t is expressed as:
wherein the actual output power and the planned output power of the ith GT are respectivelyAnd a prediction error for the distributed renewable power source output power;is a column vector with all elements having a value of 1;is a factor in the participation of the ith GT,
the objective function of the distributed robust optimization scheduling model of the integrated energy system is to minimize the total operating cost of the integrated energy system, namely:
wherein T is the number of scheduling moments; q. q.st=eTδt;NGTIs the number of GT's in the integrated energy system;andthe unit price of natural gas and electricity, respectively;andnatural gas provided by a gas source and natural gas consumed by the ith GT, respectively;is the power provided by the superior power grid;andis the cost coefficient of the ith GT;andunit prices of load interruption and load transfer in the comprehensive demand response are respectively;
introducing an auxiliary function h (q)tT) linearizing the distributed robust part of the objective functionThe helper function is as follows:
according to the strong dual theory, the distribution robust part in the objective function is expressed as
the quadratic constraint is converted into a general matrix formula with three additional linear constraints using reconstruction linearization techniques, as follows:
in the formula (I), the compound is shown in the specification,is a symmetric matrix in whichztAnd ctAre all auxiliary variables; andare each ytThe upper and lower limits of (d);
the comprehensive energy system distribution robust optimization scheduling model has the following constraint conditions:
1) distribution robust opportunity constraint: to ensure safe operation of the integrated energy system, the likelihood that the output power of the GT and the power of the distributed renewable power source deviate within their allowable ranges should be above a certain threshold; thus, the present invention employs a distributed robust opportunity constraint, as shown by the following two equations, the first of which represents the probability that the output power of the ith GT is within its range of at least 1- ε1,i(ii) a The second formula ensures that the probability that the reserve capacity of the output power of the ith GT satisfies its limit is at least 1-epsilon2,i;
In the formula, omegaGTIs a set of GT;andupper and lower limits, respectively, of the ith GT output power;is the upper limit of the ith GT reserve capacity; epsilon1,iAnd ε2,iConfidence coefficients for the two constraints, respectively;
2) other constraints are: the method comprises the following steps of electric power balance constraint, thermal power balance constraint, natural gas balance constraint, power distribution network power flow constraint, heat supply network power flow constraint and air supply network power flow constraint;
and solving the established optimized scheduling model by using a CPLEX solver on the Matlab platform to obtain the distributed robust optimized scheduling scheme of the comprehensive energy system.
Preferably, the general form of the distributed robust opportunity constraint is:
in the formula, NJIs the number of uncertainty constraints;
then, the following CVaR approximation and relaxation method is adopted to linearize the general form of the robust opportunity constraint of distribution;
in the formula, ZCVaRIs a linearized distribution robust opportunity constraint set;andare all auxiliary variables.
Compared with the prior art, the invention has the following beneficial effects:
the method disclosed by the invention has the advantages that the comprehensive demand response and the pipeline energy storage of the heat supply network and the air supply network are cooperatively modeled into the virtual energy storage, the scheduling flexibility of the comprehensive energy system can be improved, and the uncertainty of the output of the distributed renewable power supply in the comprehensive energy system is processed by utilizing a Wasserstein distance-based distributed robust optimization method.
The comprehensive energy system distribution robust optimization scheduling method obtained by the method has better economy and robustness, and the economy and the robustness of the comprehensive energy system distribution robust optimization scheduling scheme can be flexibly adjusted by changing the value of the confidence level and the number of historical samples of the output prediction error of the distributed renewable power supply; the comprehensive demand response, the heat supply network and the gas supply network pipeline energy storage cooperate to fully exert the multi-energy complementary characteristic in the comprehensive energy system, and compared with a model which considers the comprehensive demand response or the pipeline energy storage alone, the comprehensive energy system distribution robust optimization scheduling scheme obtained by the method has lower operation cost and higher renewable energy consumption rate.
Description of the drawings:
FIG. 1 is a schematic overall flow chart of the present invention. (as abstract figure)
Fig. 2 is a diagram of an integrated energy system.
Fig. 3 is a diagram of an electric power optimal scheduling strategy.
Fig. 4 is a thermal power optimal scheduling strategy diagram.
Fig. 5 is a diagram of a natural gas optimal scheduling strategy.
FIG. 6 is a graph of sensitivity analysis of a distributed robust optimization method.
Fig. 7 is a wind curtailment and optical power curtailment diagram of different optimized scheduling models.
The specific implementation mode is as follows:
in order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The first embodiment is as follows:
the invention provides a comprehensive energy system optimization scheduling method based on a distributed robust optimization method, as shown in fig. 1, the implementation process comprises the following detailed steps:
The integrated demand response is first modeled. The comprehensive demand response is composed of load interruption and load transfer of various energy sources, and the following load interruption constraint in the comprehensive demand response can be expressed as:
in the formula, the superscript t represents the scheduling period t, and the same applies below;is the interrupt power of the electrical load in the integrated demand response;is the maximum proportion of electrical load interruptions;is the electrical load in the integrated energy system.
The load shifting constraint in the integrated demand response may be expressed as:
in the formula (I), the compound is shown in the specification,is the transferred power of the electrical load in the integrated demand response;andbinary coefficients for the shifted-out electric power and the shifted-in electric power, respectively, in the integrated demand response;andrespectively, the removed electric power and the moved electric power in the integrated demand response;is the maximum proportion of electrical load transfer.
And modeling the heat supply network pipeline energy storage. The nodal method is used to model temperature quasi-dynamics and heat losses of the pipes in the heating network because it is computationally easy to process and has a high modeling accuracy.
Taking the water supply pipeline p as an example, the outlet hot water temperature can be expressed as:
in the formula (I), the compound is shown in the specification,andare each at t- (K)-1) and the temperature of the hot water at the inlet of the water supply pipe p at time t-K;is the ambient temperature of the heating network; q. q.spAnd q isp+1The mass flow rates of the water supply pipe p and the pipe connected to the outlet of the water supply pipe p, respectively; and τpThe time coefficients of the Kth mass block, the Kth mass block and the mass block at the outlet of the water supply pipeline p are respectively; k is a radical ofpAnd lpThe temperature loss coefficient and the length of the water supply pipe p, respectively.
The quasi-dynamic temperature of the pipeline in the heat supply network can be modeled as pipeline energy storage, which is defined as
In the formula (I), the compound is shown in the specification,the heat supply network pipeline stores energy; c. CwIs the specific heat capacity of water; at is the time interval between two adjacent scheduling times.
Modeling is carried out on the heat supply network pipeline energy storage. The piping in the gas supply network reflects the gas energy storage characteristics as follows:
in the formula (I), the compound is shown in the specification,andrespectively, the inventory and average node pressure of the pipeline L in the gas supply network; ZL is the inventory factor of the pipeline L;andthe gas inflow and gas outflow of the pipeline L in the gas supply network are respectively;is a collection of pipes in the air supply network.
Pipeline storage in a gas supply grid can be modeled as pipeline storage, which is defined as:
in the formula (I), the compound is shown in the specification,the energy is stored by the gas supply network pipeline.
The virtual stored energy in the integrated energy system is modeled below. Based on the above-mentioned model of synthesizing demand response, heat supply network pipeline energy storage and air supply network pipeline energy storage, with the electric power in the comprehensive energy system, the virtual energy storage definition of heating power and natural gas is for synthesizing the cooperation between demand response, heat supply network pipeline energy storage and the air supply network pipeline energy storage:
in the formula (I), the compound is shown in the specification,andrespectively, virtual energy storage for electricity, heat and natural gas.
And 2, constructing a fuzzy probability distribution set of the output uncertainty of the distributed renewable power supply in the comprehensive energy system by using a Wasserstein distance-based distribution robust optimization method.
The prediction error of the output of the ith distributed renewable power supply in the integrated energy system is a random variable and is defined as deltai. In practice, δiTrue probability distribution ofCannot be determined. However, a finite history sample of prediction errorsSome reliable probability information can be provided to obtain the empirical distributionWherein d iskTo representDirac measure of (a). Then, can be obtained byThe fuzzy set Φ is constructed with the center. To construct a well-defined fuzzy set Φ, the Wasserstein distance is used for accurate measurementAndthe distance between them.
For a given tight support space xi and two probability distributionsAndwasserstein distanceRepresented by the formula:
in the formula (I), the compound is shown in the specification,is to have an empirical distributionA random variable of (a); j is atAnda joint distribution which is an edge distribution;is the distance between two random variables, using 1-norm | · | | luminance1Because it has excellent numerical scalability in the DRO problem.
It should be noted that the method can be implemented byIt is regarded as having a radiusAnd are distributed empiricallyA central Wasserstein ball.
The method is very important for the performance of a distributed robust optimization scheduling method based on Wasserstein distance, and can control the conservatism of a scheduling strategy. Construction ofA usable historical sample based on prediction error is needed, as follows:
in the formula (I), the compound is shown in the specification,is deltaiThe confidence of (2); η is an auxiliary variable;is the average of historical samples of prediction error; nsam is the number of historical samples of prediction error.Can be obtained by a binary search method.
And 3, constructing a comprehensive energy system distribution robust optimization scheduling model based on the virtual energy storage model and the fuzzy probability distribution set, and solving a comprehensive energy system optimization scheduling strategy based on a distribution robust optimization method.
The power deviation caused by the distributed renewable power source contribution prediction error is distributed to each Gas Turbine (GT), and the actual output power of the ith GT at time t can be expressed as:
wherein the actual output power and the planned output power of the ith GT are respectivelyAnd a prediction error for the distributed renewable power source output power;is a column vector with all elements having a value of 1;is a factor in the participation of the ith GT,
the objective function of the distributed robust optimization scheduling model of the comprehensive energy system based on the distributed robust optimization method is to minimize the total operating cost of the comprehensive energy system, namely:
wherein T is the number of scheduling moments; q. q.st=eTδt;NGTIs the number of GT's in the integrated energy system;andthe unit price of natural gas and electricity, respectively;andnatural gas provided by a gas source and natural gas consumed by the ith GT, respectively;is the power provided by the superior power grid;andis the cost coefficient of the ith GT;andrespectively, unit prices for load interruption and load shifting in the integrated demand response.
An objective function of a distributed robust optimization scheduling model of the comprehensive energy system based on the distributed robust optimization method is a 'min-max' problem and is difficult to directly solve.
To linearize the distributed robust part of the objective function, i.e.Introducing an auxiliary function h (q)tT) is defined as
According to the strong dual theory, the distribution robust part in the objective function can be expressed as
Thus, the distribution robust part of the objective function has been converted to a linear formulation by strong dual theory and can be easily solved by commercial solvers. However, newly introduced quadratic constraints still need to be handled. The reconstruction linearization technique is effective in solving the quadratic constraint, therefore, the present invention applies the reconstruction linearization technique to convert the quadratic constraint into a general matrix formula with three additional linear constraints, as follows:
in the formula (I), the compound is shown in the specification,is a symmetric matrix in whichztAnd ctAre all auxiliary variables; andare each ytUpper and lower limits of (d).
The comprehensive energy system distribution robust optimization scheduling model based on the distribution robust optimization method has the following constraint conditions:
1) distribution robust opportunity constraint: to ensure safe operation of the integrated energy system, the likelihood that the output power of the GT and the power of the distributed renewable power source deviate within their allowable ranges should be above a certain threshold. Therefore, the present invention employs a distributed robust opportunity constraint, as shown in the following two equations. The first formula represents the output of the ith GTThe probability of the power being in its range being at least 1-epsilon1,i(ii) a The second formula ensures that the probability that the reserve capacity of the output power of the ith GT satisfies its limit is at least 1-epsilon2,i。
In the formula, omegaGTIs a set of GT;andupper and lower limits, respectively, of the ith GT output power;is the upper limit of the ith GT reserve capacity; epsilon1,iAnd ε2,iRespectively, the confidence coefficients of the two constraints.
The two above distributed robust opportunistic constraints are non-convex constraints, which results in the model proposed by the present invention not being easily solved by commercial solvers. The CVaR approximation and relaxation method has proven to be effective in linearizing the opportunity constraints, so the present invention uses this method to linearize the two above distributed robust opportunity constraints. For ease of description, a general form of the distributed robust opportunity constraint is first given:
in the formula, NJIs the number of uncertainty constraints.
The general form of distributing the robust opportunity constraint is then linearized by the CVaR approximation and relaxation method as follows:
in the formula, ZCVaRIs a linearized distribution robust opportunity constraint set;andare all auxiliary variables.
2) Other constraints are: the method comprises electric power balance constraint, thermal power balance constraint, natural gas balance constraint, power distribution network power flow constraint, heat supply network power flow constraint and air supply network power flow constraint.
So far, a comprehensive energy system distribution robust optimization scheduling model based on a distribution robust optimization method is established. And solving the model by using a CPLEX solver on the Matlab platform to obtain the comprehensive energy system distribution robust optimization scheduling scheme.
The first application embodiment:
for further understanding of the present invention, the practical application of the present invention will be explained below by taking an integrated energy system consisting of an IEEE-33 node distribution network, a 44 node heating network and a 20 node gas supply network as an example.
The structure diagram of the comprehensive energy system consisting of an IEEE-33 node power distribution network, a 44 node heat supply network and a 20 node gas supply network is shown in figure 2, and the three energy networks of the power distribution network, the heat supply network and a natural gas network are coupled through a gas turbine GT, an electric gas conversion device P2G, an electric boiler EB and a cogeneration unit CHP in an energy hub.
The optimal scheduling strategy for electricity, heat and gas in the IES is shown in fig. 3-5. As can be seen from fig. 3, the DG contribution in the IES is sufficient during the entire dispatch period, so the IES does not need to buy power from the upper grid, and the RES output power needs to be reduced even in the evening or midday time periods when the RES contribution is large. Since the output power of Photovoltaic (PV) at 13:00 is large and the electricity price of 13:00 is low, at 13:00, 1.6MW of PV power is stored in VES and discharged during the high electricity price period of 16:00-21:00, which can reduce the operating cost of IES and light rejection. As can be seen from fig. 4, the EB is running at full power throughout the scheduling period to increase the renewable energy consumption rate. Since the CHP is operated in "on-demand" mode and the heat load is greater during the night than during the day, the CHP has greater thermal and electrical power during the night. As can be seen from fig. 2, the output power of Wind Turbine (WT) is larger at night, and the electrical load is lower, so that the larger electrical power of CHP at night may result in more wind curtailment. Thus, the VES releases thermal energy at 1:00-11:00 and 23:00-24:00 to reduce the CHP thermal power and thus reduce the WT output power. As can be seen from fig. 5, P2G, the gas source and the virtual energy storage together supply the natural gas load and the natural gas demand of the CHP and GT during the entire dispatch.
Table 1 shows a robust optimization method based on distributionAnd comparing the operation cost of the comprehensive energy system between the stochastic programming method and the robust optimization method comprehensive energy system optimization scheduling model. As can be seen from table 1, the operation cost of the distributed robust optimization method is lower than that of the robust optimization method and higher than that of the stochastic programming method because the robust optimization method completely ignores probability information, and the stochastic programming method assumes an accurate probability distribution of uncertainty in the integrated energy system. In other words, the robust optimization method and the stochastic programming method respectively give out over-optimization and over-conservative scheduling strategies of the comprehensive energy system, the distributed robust optimization method establishes a fuzzy set containing all possible probability distributions based on historical samples of random variables in the comprehensive energy system, and compared with the stochastic programming method, the optimistic degree is lower, and the conservative degree is lower than that of the robust optimization method. As can be seen from table 1, the operation cost of the distributed robust optimization method decreases with the increase of the historical sample amount of the prediction error, that is, when the historical sample amount is smaller, the distributed robust optimization method adopts the conservative scheduling strategy of the image robust optimization method; conversely, when the historical sample size of the prediction error is largeThe distributed robust optimization method would use an optimistic scheduling strategy similar to the stochastic programming method. The reason is that when the historical sample size is small, the probability distribution which can be extracted is limited, so that the Wasserstein ball boundary is wider, and the scheduling strategy of the comprehensive energy system is more conservative; with the increase of the historical sample size, the radius of the Wasserstein ball is reduced, the fuzzy set is smaller, and the conservatism of the scheduling strategy of the comprehensive energy system is also reduced.
TABLE 1 comparison of integrated energy system operating costs between integrated energy system optimization scheduling models based on a distributed robust optimization method, a stochastic programming method, and a robust optimization method
In order to analyze the sensitivity of the model provided by the present invention to the confidence and the number of samples, the comparison between the operation cost of the integrated energy system and the Renewable Energy Consumption Level (RECL) at different confidence and the number of samples is shown in fig. 6. As can be seen from fig. 6, as the confidence level increases, the operation cost of the integrated energy system increases, and the RECL of the integrated energy system decreases, because as the confidence level β increases, the scheduling strategy of the integrated energy system tends to be more conservative. Furthermore, as the historical sample size increases, the operating cost of the integrated energy system decreases, while the RECL of the integrated energy system increases, because as the historical sample size increases, the fuzzy set shrinks and the conservatism of the integrated energy system scheduling strategy decreases. Therefore, the model can adjust the economy and robustness of the integrated energy system scheduling strategy according to the confidence coefficient and the historical sample number.
In order to verify the effectiveness of the model provided by the invention, an optimal scheduling model (M-WIP) of the comprehensive energy system without considering comprehensive demand response and pipeline energy storage, an optimal scheduling model (M-PESs) of the comprehensive energy system with considering pipeline energy storage, an optimal scheduling model (M-IDR) of the comprehensive energy system with considering comprehensive demand response and the model (M-VES) provided by the invention with considering virtual energy storage are compared. Table 2 shows the comparison of the M-WIP, the M-PESs, the M-IDR and the M-VES provided by the invention in the aspects of the running cost and the RECL of the integrated energy system, and the four models all use a Wasserstein distance-based distributed robust optimization method to process the uncertainty of the output of the distributed renewable power supply. As can be seen from Table 2, the operating cost of M-VES was 2.8%, 0.8% and 1.4% lower than M-WIP, M-PES and M-IDR, respectively. Furthermore, the RECL of M-VES was 5.8%, 1.4% and 3.4% higher than M-WIP, M-PES and M-IDR, respectively. This is because the virtual energy storage (i.e. the cooperation between the IDR and the pipeline energy storage) can fully utilize the complementary characteristics of multiple energies to enhance the scheduling flexibility of the integrated energy system, so that the operation cost of the integrated energy system can be reduced and the RECL can be improved. The comparison of the M-PES and the M-IDR shows that the comprehensive demand response and the pipeline energy storage can reduce the operation cost of the comprehensive energy system and improve the RECL of the REC, and the performance of the pipeline energy storage is superior to that of the comprehensive demand response.
TABLE 1 comparison of M-WIP, M-PESs, M-IDR and M-VES as proposed by the invention in terms of integrated energy system operating costs and RECL
FIG. 7 shows a comparison between M-WIP, M-PES, M-IDR and M-VES of the present invention for reducing wind curtailment. As can be seen from fig. 7, the wind curtailment and light curtailment of the distributed renewable power source occur at 1:00-14:00 and 23:00-24:00, since the distributed renewable power sources are very powerful and the electrical load is very low during these periods. Due to the lack of comprehensive demand response and pipeline energy storage, M-WIP cannot utilize the multi-energy complementation of the comprehensive energy system to promote renewable energy consumption, thus reducing 16.2MW of wind-solar output during the entire dispatch period. Pipeline energy storage and integrated demand response are used in the M-PES and M-IDR, respectively, so that RECL of the M-PES and M-IDR is improved. The M-VESs provided by the invention considers the synergistic effect between pipeline energy storage and comprehensive demand response so as to fully utilize the multi-energy complementary characteristic of a comprehensive energy system, so that the wind curtailment of the M-VESs is the lowest in the four models.
Claims (6)
1. A comprehensive energy system optimization scheduling method based on a distributed robust optimization method is characterized by comprising the following steps: the method comprises the following steps:
constructing a virtual energy storage model in the comprehensive energy system;
constructing a fuzzy probability distribution set of the output uncertainty of the distributed renewable power supply in the comprehensive energy system by adopting a Wasserstein distance-based distribution robust optimization method;
and constructing a comprehensive energy system distribution robust optimization scheduling model based on the virtual energy storage model and the fuzzy probability distribution set, and solving a comprehensive energy system optimization scheduling strategy based on a distribution robust optimization method.
2. The integrated energy system optimization scheduling method based on the distributed robust optimization method according to claim 1, wherein: the virtual energy storage in the integrated energy system comprises integrated demand response, heat supply network pipeline energy storage and air supply network pipeline energy storage.
3. The integrated energy system optimization scheduling method based on the distributed robust optimization method according to claim 2, wherein:
the method for constructing the virtual energy storage model in the comprehensive energy system comprises the following steps:
firstly, modeling a comprehensive demand response, wherein the comprehensive demand response comprises a load interruption constraint and a load transfer constraint, and the load interruption constraint in the comprehensive demand response is expressed as follows:
in the formula, the superscript t represents the scheduling period t, and the same applies below;is the interrupt power of the electrical load in the integrated demand response;is the maximum proportion of electrical load interruptions;is the electrical load in the integrated energy system;
the load shifting constraint in the integrated demand response is expressed as:
in the formula (I), the compound is shown in the specification,is the transferred power of the electrical load in the integrated demand response;andbinary coefficients for the shifted-out electric power and the shifted-in electric power, respectively, in the integrated demand response;andrespectively, the removed electric power and the moved electric power in the integrated demand response;is the maximum proportion of electrical load transfer;
and then modeling the energy storage of the pipeline of the heat supply network, and modeling the temperature quasi-dynamics and the heat loss of the pipeline in the heat supply network by adopting a node method, wherein the temperature of the outlet hot water of the water supply pipeline p is expressed as follows:
in the formula (I), the compound is shown in the specification,andthe hot water temperatures at the inlet of the water supply pipe p at times t- (K-1) and t-K, respectively;is the ambient temperature of the heating network; q. q.spAnd q isp+1The mass flow rates of the water supply pipe p and the pipe connected to the outlet of the water supply pipe p, respectively;and τpThe time coefficients of the Kth mass block, the Kth mass block and the mass block at the outlet of the water supply pipeline p are respectively; k is a radical ofpAnd lpThe temperature loss coefficient and the length of the water supply pipe p, respectively;
the heating network pipeline energy storage is expressed as:
in the formula (I), the compound is shown in the specification,the heat supply network pipeline stores energy; c. CwIs the specific heat capacity of water; Δ t is the time interval between two adjacent scheduling times;
modeling the energy storage of the gas supply network pipeline, namely modeling the pipe storage and the average node pressure of the pipeline L in the gas supply network:
in the formula (I), the compound is shown in the specification,andrespectively, the inventory and average node pressure of the pipeline L in the gas supply network; zLIs a pipelineL(ii) a inventory factor of;andthe gas inflow and gas outflow of the pipeline L in the gas supply network are respectively;is a collection of pipes in an air supply network;
the gas supply network pipeline energy storage is expressed as
In the formula (I), the compound is shown in the specification,the gas supply network pipeline stores energy;
and finally, modeling virtual energy storage in the comprehensive energy system, and defining the virtual energy storage of the electric power, the heating power and the natural gas in the comprehensive energy system as the cooperation among the comprehensive demand response, the heat supply network pipeline energy storage and the air supply network pipeline energy storage based on the model of the comprehensive demand response, the heat supply network pipeline energy storage and the air supply network pipeline energy storage:
4. The integrated energy system optimization scheduling method based on the distributed robust optimization method according to claim 1, wherein:
a distributed robust optimization method based on Wasserstein distance is applied to construct a fuzzy probability distribution set of the output uncertainty of a distributed renewable power supply in a comprehensive energy system, and the fuzzy probability distribution set comprises the following steps:
defining the prediction error of the output of the ith distributed renewable power source in the integrated energy system as deltai,δiFor random variables, note deltaiHas a true probability distribution of
Limited historical samples based on prediction errorObtaining an empirical distributionWherein d iskTo representThe Dirac measure of (a);
then by mixingSetting the fuzzy set phi as a center to construct a fuzzy set phi; in the fuzzy set of values phi,andthe distance between the two is measured by Wasserstein distance;
for a given tight support space xi and two probability distributionsAndwasserstein distanceRepresented by the formula:
in the formula (I), the compound is shown in the specification,is to have an empirical distributionA random variable of (a); j is atAnda joint distribution which is an edge distribution;is the distance of two random variables;
wherein
In the formula (I), the compound is shown in the specification,is deltaiThe confidence of (2); η is an auxiliary variable;is the average of historical samples of prediction error; n is a radical ofsamIs the number of historical samples of prediction error;the result is obtained by a binary search method.
5. The integrated energy system optimization scheduling method based on the distributed robust optimization method according to claim 1, wherein:
constructing a comprehensive energy system distribution robust optimization scheduling model based on the virtual energy storage model and the fuzzy probability distribution set, and solving a comprehensive energy system optimization scheduling strategy based on a distribution robust optimization method, wherein the comprehensive energy system optimization scheduling strategy comprises the following steps:
the power deviation caused by the distributed renewable power source contribution prediction error is distributed to each gas turbine GT, and the actual output power of the ith GT at time t is expressed as:
wherein the actual output power and the planned output power of the ith GT are respectivelyAnd a prediction error for the distributed renewable power source output power;is a column vector with all elements having a value of 1;is a factor in the participation of the ith GT,
the objective function of the distributed robust optimization scheduling model of the integrated energy system is to minimize the total operating cost of the integrated energy system, namely:
wherein T is the number of scheduling moments; q. q.st=eTδt;NGTIs the number of GT's in the integrated energy system;andthe unit price of natural gas and electricity, respectively;andnatural gas provided by a gas source and natural gas consumed by the ith GT, respectively;is the power supplied by the upper grid;Andis the cost coefficient of the ith GT;andunit prices of load interruption and load transfer in the comprehensive demand response are respectively;
introducing an auxiliary function h (q)tT) linearizing the distributed robust part of the objective functionThe helper function is as follows:
according to the strong dual theory, the distribution robust part in the objective function is expressed as
the quadratic constraint is converted into a general matrix formula with three additional linear constraints using reconstruction linearization techniques, as follows:
in the formula (I), the compound is shown in the specification,is a symmetric matrix in whichztAnd ctAre all auxiliary variables; andare each ytThe upper and lower limits of (d);
the comprehensive energy system distribution robust optimization scheduling model has the following constraint conditions:
1) distribution robust opportunity constraint: to ensure safe operation of the integrated energy system, the likelihood that the output power of the GT and the power of the distributed renewable power source deviate within their allowable ranges should be above a certain threshold; thus, the present invention employs a distributed robust opportunity constraint, as shown by the following two equations, the first of which represents the probability that the output power of the ith GT is within its range of at least 1- ε1,i(ii) a The second formula ensures that the probability that the reserve capacity of the output power of the ith GT satisfies its limit is at least 1-epsilon2,i;
In the formula, omegaGTIs a set of GT;andupper and lower limits, respectively, of the ith GT output power;is the upper limit of the ith GT reserve capacity; epsilon1,iAnd ε2,iConfidence coefficients for the two constraints, respectively;
2) other constraints are: the method comprises the following steps of electric power balance constraint, thermal power balance constraint, natural gas balance constraint, power distribution network power flow constraint, heat supply network power flow constraint and air supply network power flow constraint;
and solving the established optimized scheduling model by using a CPLEX solver on the Matlab platform to obtain the distributed robust optimized scheduling scheme of the comprehensive energy system.
6. The integrated energy system optimization scheduling method based on the distributed robust optimization method according to claim 5, wherein: the general form of the distributed robust opportunity constraint is:
in the formula, NJIs the number of uncertainty constraints;
then, the following CVaR approximation and relaxation method is adopted to linearize the general form of the robust opportunity constraint of distribution;
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CN115688394A (en) * | 2022-10-18 | 2023-02-03 | 上海科技大学 | V2G distribution robust optimization method considering multiple uncertainties of power grid |
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CN115688394A (en) * | 2022-10-18 | 2023-02-03 | 上海科技大学 | V2G distribution robust optimization method considering multiple uncertainties of power grid |
CN115688394B (en) * | 2022-10-18 | 2023-12-26 | 上海科技大学 | V2G distribution robust optimization method considering multiple uncertainties of power grid |
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CN116780649B (en) * | 2023-06-16 | 2024-03-01 | 国网浙江省电力有限公司嘉兴供电公司 | Multi-energy complementary utilization distributed robust optimization operation method |
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