A method and system for quantifying dynamic energy storage characteristics of multi-energy network in integrated energy system

Abstract

The present invention discloses a method and system for quantifying the dynamic energy storage characteristics of a multi-energy network of an integrated energy system. The method starts from the dynamic modeling of the fluid network, and evaluates the operation and design of the energy flow transport network through quantitative indicators according to the transport characteristics and energy storage characteristics of different energy flows in the pipeline network. The method comprises the following steps: step S1, establishing and solving a dynamic model of a fluid network containing a topological structure according to the mass, momentum, and energy conservation equations; step S2, establishing a generalized energy storage model, and calculating the energy storage characteristic parameters of the fluid network; step S3, establishing a method for quantifying the energy storage characteristics of the fluid transport network, and using quantitative indicators to evaluate its energy storage capacity and utilization rate; step S4, using the established fluid transport network energy storage characteristics to quantitatively evaluate different transport networks for the same fluid or different operating conditions of the same transport network. The method of the present invention can quantitatively evaluate the dynamic energy storage characteristics of the fluid transport network, and support the integrated energy system to achieve scheduling optimization.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated energy system operation control, and specifically relates to a method and system for quantifying dynamic energy storage characteristics of a multi-energy network of an integrated energy system. Background Art

[0002] The integrated energy system has the advantages of integrating multiple energy resources, coordinating the management of heterogeneous energy flows, and realizing multi-energy complementarity and cascade utilization of energy. It is one of the key technologies to achieve the "dual carbon" goal. The fluid transportation network is an important part of the "source, grid, load and storage" of the integrated energy system, and is also an important link to deeply participate in the planning and regulation of the integrated energy system. The fluid energy flows in the integrated energy system include natural gas, hot water, cold water, steam, and compressed air. Unlike the power transmission network, the fluid is compressible and delayed when it is transported in the network, and its supply and utilization do not need to be balanced in real time, which provides the possibility of improving the energy storage of the fluid transportation network and the flexibility of the integrated energy system. Making full use of the energy storage capacity of the fluid transportation network can improve the energy utilization efficiency, user demand response capability, system operation economy and environmental protection of the integrated energy system without adding additional energy storage equipment, further promote the consumption of renewable energy, and help achieve the "dual carbon" goal.

[0003] However, the current understanding and analysis of the dynamic energy storage capacity and energy storage characteristics of the fluid transport network is not sufficient to help achieve flexible scheduling of the integrated energy system. Therefore, starting from the dynamic modeling of the fluid transport network, further revealing its dynamic energy storage characteristics and evaluating its energy storage capacity are the premise and basis for its application in the field of integrated energy system scheduling. In order to further give play to the energy storage capacity of the fluid transport network, it is necessary to establish a quantitative evaluation method for the energy storage characteristics of the transport network of the integrated energy system. Summary of the invention

[0004] The purpose of the present invention is to address the deficiencies in the prior art and provide a method and system for quantifying the dynamic energy storage characteristics of a multi-energy network in an integrated energy system. The present invention quantifies the energy storage characteristics and capabilities of the transmission network in the integrated energy system, and can provide a basis for optimizing the scheduling of the integrated energy system.

[0005] The present invention is implemented by the following technical solutions:

[0006] A method and system for quantifying dynamic energy storage characteristics of a multi-energy network of an integrated energy system, comprising the following steps:

[0007] Step S1, establishing and solving a fluid network dynamic model containing a topological structure according to the mass, momentum and energy conservation equations;

[0008] Step S2, establishing a generalized energy storage model and calculating energy storage characteristic parameters of the fluid network;

[0009] Step S3, establishing a method for quantifying the energy storage characteristics of a fluid transport network, and using quantitative indicators to evaluate its energy storage capacity and utilization rate;

[0010] Step S4, using the established fluid transport network energy storage characteristic quantification method to evaluate different transport networks for the same fluid or different operating conditions of the same transport network.

[0011] In step S1, a fluid network dynamic model with a topological structure is established and solved according to the mass, momentum and energy conservation equations:

[0012] Step S11: Establishing a fluid transport dynamics model

[0013]

[0014] in:

[0015]

[0016]

[0017] Where, the subscript i represents energy flow i, which includes natural gas, compressed air, hot water, cold water, and steam; ρ i is the density, kg / m 3 ;v i is the speed, m / s; P i is pressure, MPa; u i is the specific internal energy, J / kg; g i is the acceleration due to gravity, m / s 2 θ i is the pipeline inclination angle, °; λ i D is the drag coefficient; i is the pipe diameter, m; K i is the heat transfer coefficient, W / (m 2 ·K); T i is the fluid temperature, K; T i,r is the ambient temperature, K.

[0018] For gas energy flow, such as natural gas and compressed air, the gas temperature does not change during the transportation process, and the mass and momentum equations are combined to describe the gas energy flow transportation process; for liquid energy flow, such as hot water and cold water, the liquid density does not change during the transportation process, and the momentum and energy equations are combined to describe the liquid energy flow transportation process; for the special energy flow steam, its density and temperature will change during the transportation process due to the influence of source side supply and environment, and the mass, momentum and energy equations need to be combined to describe its transportation process.

[0019] Step S12: Establishing a fluid network transport dynamics model

[0020] According to graph theory, the node-branch matrix is ​​defined to describe the fluid topology.

[0021]

[0022]

[0023] In the formula, A i is the node-branch association matrix of energy flow i; n is the number of nodes; m is the number of branches; a nm is the correlation coefficient between node n and branch m.

[0024] At the same time, the fluid network constraints of energy flow i are established

[0025] For natural gas and compressed air, for any node j in the fluid network of energy flow i, establish the flow balance equation

[0026] ∑G i,j (t)+∑G o,j (t) = 0

[0027] Where: ∑G i,j (t) is the mass flow rate flowing into node j at time t, kg / s; ∑G o,j (t) is the mass flow rate out of node j at time t, kg / s.

[0028] For hot water and cold water, the node energy balance equation is:

[0029] ∑E i,j (t)+∑E o,j (t) = 0

[0030] Where: E i,j (t) is the energy flowing into node j, J; E o,j (t) is the energy flowing out of node j, J.

[0031] For steam, the network constraints should include both flow balance and energy balance.

[0032] Combined with the formula in step S11, a fluid network transport dynamics model with a topological structure can be established to describe the fluid transport process;

[0033] Step S13, to simplify the calculation, gas-like fluids and special fluids are regarded as ideal gases and phase change is not considered, and a simplified model of the ideal gas state equation is introduced. According to the fluid characteristics, a suitable ordinary differential equation, partial differential equation solution method or finite difference method is selected to solve the fluid network transport dynamics model to obtain the distribution of fluid density, velocity, and temperature in time and space.

[0034] In step S2 of establishing a generalized energy storage model and calculating energy storage characteristic parameters of the fluid network:

[0035] Step S21, establish a generalized energy storage model. Compare the fluid network energy storage to a generalized energy storage device, and use real-time storage / discharge rate, real-time storage / discharge amount, real-time total storage amount, maximum / minimum storage amount, required storage amount, and initial storage amount to describe the storage and discharge characteristics of the generalized energy storage model;

[0036] Step S22, based on the solution result of the fluid network transport dynamics model in step S1, calculate the energy storage characteristic parameters of the generalized energy storage model.

[0037] The real-time storage / discharge rate describes the real-time supply-demand imbalance. When supply exceeds demand, the real-time storage / discharge rate is positive, indicating that the generalized energy storage model is storing energy; when supply is less than demand, the real-time storage / discharge rate is negative, indicating that the generalized energy storage model is discharging energy.

[0038] S rt (t) = μ in (t)-μ out (t)

[0039] In the formula, S rt (t) is the real-time energy storage / discharge rate; μ in (t), μ out (t) are the energy of fluid injected and outflowed at time t.

[0040] Real-time storage / discharge energy describes the fluctuation of the generalized energy storage model around the initial storage energy during operation. The initial storage energy is the energy stored in the network at the initial point of scheduling of the generalized energy storage model. The maximum and minimum storage energy describe the upper and lower limits of the energy storage of the generalized energy storage model, which together constitute the maximum energy storage capacity of the fluid network and the constraints of real-time storage / discharge energy.

[0041]

[0042] In the formula, is the real-time storage / release of energy; dt is the time step; For maximum energy storage; is the minimum stored energy; For initial energy storage; is the real-time total storage energy; S max For maximum energy storage capacity.

[0043] For gaseous fluids, the maximum / minimum storage energy is described as

[0044]

[0045] In the formula, R g,i is the gas constant; are the maximum pressures at the inlet and outlet of the generalized energy storage model, respectively; are the minimum pressures at the inlet and outlet of the generalized energy storage model; M i is the area of ​​the ith pipe, m 2 ; L i is the length of the i-th pipeline, m; T is the gas temperature, K; is the average density of the ith pipe, kg / m 3 ; np is the number of pipelines.

[0046] For liquid fluids, the maximum / minimum storage energy is described as

[0047]

[0048] In the formula, is the average specific heat capacity, J / (kg·K); G is the flow rate, kg / s; T s max , T s min are the highest and lowest temperatures of the water supply, K; T r max , T r min are the highest and lowest return water temperatures, K respectively.

[0049] For steam fluid, the maximum / minimum energy storage is described as

[0050]

[0051] The required storage capacity describes the energy that the generalized energy storage model must store in order to meet the supply on the demand side during operation. s is the total energy supply curve, Q c is the total energy demand curve, and the storage capacity of the generalized energy storage model is described as the integral of the supply and demand difference

[0052]

[0053] In the formula, ΔS d (t) is the energy storage curve. Then the required storage energy can be described as

[0054] S e =QA-QB

[0055] Where QA and QB are the highest and lowest points of the energy storage curve respectively.

[0056] It should be noted that the calculation of the dynamic model of the steam transport network is relatively complex. The existing simplified calculations include ignoring the change in steam temperature and ignoring the change in steam density. For the simplified solution that ignores the change in steam temperature, the calculation method of the heat storage and release characteristics of the generalized energy storage model is the same as that of the gas type energy flow; for the simplified solution that ignores the change in steam density, the calculation method of the heat storage and release characteristics of the generalized energy storage model is the same as that of the liquid type energy flow.

[0057] In step S3 of establishing a quantitative evaluation model for the energy storage characteristics of a fluid transport network to evaluate its energy storage capacity and utilization rate:

[0058] A quantitative evaluation model for the energy storage characteristics of fluid transport networks is established, including two evaluation indicators: satisfaction and comprehensive utilization rate. Satisfaction refers to the satisfaction of the maximum energy storage capacity of the generalized energy storage model with the system scheduling requirements. It is used to evaluate the energy storage potential of a specific generalized energy storage model and its storage and discharge energy redundancy during the scheduling process.

[0059]

[0060] In the formula, χ is the satisfaction degree.

[0061] Comprehensive utilization rate evaluates the utilization of the energy storage capacity of the generalized energy storage model by the system dispatch strategy during actual operation. First, calculate the positive utilization rate and negative utilization rate.

[0062]

[0063] Where η + is a positive utilization rate; η - Negative utilization.

[0064] Secondly, calculate the maximum and average of positive and negative utilization

[0065]

[0066]

[0067] In the formula, t d is the scheduling period; is the maximum value of positive utilization; is the maximum value of negative utilization; is the average value of positive utilization; It is the maximum value of negative utilization.

[0068] Use the expert evaluation method to comprehensively evaluate the utilization rate of the generalized energy storage model and calculate the comprehensive utilization rate index

[0069]

[0070]

[0071] Where, η is the comprehensive utilization rate; w k is the weight of the kth item utilization; η k is the kth item utilization. η1 is the maximum value of positive utilization; η2 is the average value of positive utilization; η3 is the maximum value of negative utilization; η4 is the average value of negative utilization. Among them, the weight is given by the expert evaluation method.

[0072] In step S4, in quantitatively evaluating different transport networks for the same fluid or different operating conditions of the same transport network using the established fluid transport network energy storage characteristics:

[0073] Step S41, input different transmission networks of the same energy flow, and calculate the satisfaction of multiple transmission networks according to steps S1-S3. The greater the satisfaction, the more the generalized energy storage model can meet the energy storage and release requirements in the scheduling strategy, that is, the design of the transmission network is more matched with the actual operation scheduling; when the satisfaction is less than 1, it means that the generalized energy storage model is not sufficient to support the scheduling needs of the system, and additional energy storage equipment is required. The satisfaction can be used to evaluate the network planning of different transmission networks for the same energy flow, and can also be used to evaluate the planning scheme of the energy flow transmission network. Under the same economic conditions, the higher the satisfaction, the more reasonable the network planning.

[0074] Step S42, input different operating conditions of the same energy flow and the same transmission network, and calculate the comprehensive utilization rate under different operating conditions according to steps S1-S3 to evaluate the utilization of the energy storage capacity of the transmission network by different operating conditions and their scheduling schemes. The operating condition with high comprehensive utilization rate indicates that the generalized energy storage model is deeply involved in the scheduling, its energy storage capacity is more fully utilized, and the scheduling strategy makes more full use of the design configuration of the generalized energy storage model.

[0075] The present invention also provides a comprehensive energy system transmission network energy storage characteristics quantitative evaluation system, the system includes a data processing module, a fluid network transmission dynamics model modeling and solution module, a generalized energy storage model modeling and calculation module, and an energy storage characteristics quantitative evaluation module; the above modules are respectively encapsulated to establish a data transmission channel;

[0076] The data processing module processes the input integrated energy system fluid transport network parameters and operation data, and transmits the processed data to the fluid network transport dynamic model modeling and solution module;

[0077] The fluid network transport dynamic model modeling and solution module establishes a fluid network dynamic model with a topological structure according to the fluid characteristics, simplifies the mass, momentum and energy equations, selects a solution method to solve the fluid network dynamic model, and transmits the spatiotemporal distribution data of density, velocity and temperature to the generalized energy storage model calculation module;

[0078] The generalized energy storage model modeling and calculation module is used to establish a generalized energy storage model, calculate the energy storage and release characteristics of the fluid network, calculate six key parameters including real-time energy storage / release rate, real-time energy storage / release amount, real-time total energy storage, maximum / minimum energy storage, required energy storage, and initial energy storage, and transmit the calculation results to the energy storage characteristic quantitative evaluation module;

[0079] The energy storage characteristic quantitative evaluation module calculates two indicators, namely, satisfaction and comprehensive utilization rate, and evaluates different transport networks of the same fluid from the perspective of energy storage potential, and evaluates and analyzes different operating conditions of the same transport network from the perspective of comprehensive energy storage utilization rate, and obtains quantitative evaluation results respectively.

[0080] The beneficial effects of the present invention are:

[0081] The present invention establishes a method and system for quantifying the dynamic energy storage characteristics of a multi-energy network of an integrated energy system. A dynamic model of a fluid transport network is established based on the three conservation equations of mass, momentum and energy and the topological structure of a fluid network, and the model is simplified according to the fluid characteristics, and a suitable solution method is selected for solving it; a generalized energy storage model is established to quantify the energy storage characteristics of the fluid transport network, and the energy storage characteristic parameters of the fluid transport network are calculated based on the solution results of the spatiotemporal distribution of density, velocity and temperature; an energy storage evaluation system for a generalized energy storage model is established, and the energy storage potential and energy storage utilization rate of the generalized energy storage model in planning and scheduling are evaluated by using satisfaction and comprehensive utilization rate, which is used to evaluate and analyze the energy storage conditions of different transport networks of the same fluid or different operating conditions of the same transport network, so as to provide a model and constraint basis for the fluid transport network to participate in the scheduling optimization of the integrated energy system, thereby increasing the adjustment flexibility of the integrated energy system. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 is a quantitative evaluation flow chart of the present invention;

[0083] Figure 2 This is the transport network structure diagram of a steam system;

[0084] Figure 3 It is a real-time energy storage and release rate diagram of a steam system;

[0085] Figure 4 The positive and negative utilization results of a steam system; DETAILED DESCRIPTION

[0086] In order to make the content of the present invention more clearly understood, the technical solution of the present invention is further introduced below in conjunction with specific examples and drawings. Figure 1 As shown, the technical method of the present invention includes 4 steps:

[0087] Step S1, establishing and solving a fluid network dynamic model containing a topological structure according to the mass, momentum and energy conservation equations;

[0088] Step S2, establishing a generalized energy storage model and calculating energy storage characteristic parameters of the fluid network;

[0089] Step S3, establishing a quantitative evaluation model for the energy storage characteristics of the fluid transport network to evaluate its energy storage capacity and utilization rate;

[0090] Step S4, using the established fluid transport network energy storage characteristic quantification method evaluation model to evaluate and analyze different transport networks for the same fluid or different operating conditions of the same transport network.

[0091] Combine the following Figure 2 The present invention is further described with reference to the steam system of the topological structure shown in FIG. Two operating conditions, operating condition 1 and operating condition 2, in December are selected as research cases.

[0092] In step S1, according to the mass, momentum and energy conservation equations, a dynamic model of the fluid network of the steam system with topological structure is established and solved:

[0093] Step S11: Establishing a steam transport dynamics model

[0094]

[0095] in:

[0096]

[0097]

[0098] Where, the subscript i represents steam; ρ i is the density, kg / m 3 ;v i is the speed, m / s; P i is pressure, MPa; u i is the specific internal energy, J / kg; g i is the acceleration due to gravity, m / s 2 θ i is the pipeline inclination angle, °; λ i D is the drag coefficient; i is the pipe diameter, m; K i is the heat transfer coefficient, W / (m 2 ·K); T i is the fluid temperature, K; T i,r is the ambient temperature, K.

[0099] Step S12: Establishing a steam network transport dynamics model

[0100] According to graph theory, the node-branch matrix is ​​defined to describe the fluid topology.

[0101]

[0102]

[0103] In the formula, A i is the node-branch association matrix of steam; n is the number of nodes; m is the number of branches; a nm is the correlation coefficient between node n and branch m.

[0104] Simultaneously establish steam network constraints

[0105] For any node j in the steam network, establish the flow balance equation

[0106] ∑G i,j (t)+∑G o,j (t) = 0

[0107] Where: ∑G i,j (t) is the mass flow rate flowing into node j at time t, kg / s; ∑G o,j (t) is the mass flow rate out of node j at time t, kg / s.

[0108] The node energy balance equation is:

[0109] ∑E i,j (t)+∑E o,j (t) = 0

[0110] Where: E i,j (t) is the energy flowing into node j, J; E o,j (t) is the energy flowing out of node j, J.

[0111] The formula in step S11 can be combined to establish a steam network transport dynamics model with a topological structure to describe the steam transport process;

[0112] Step S13, to simplify the calculation, the steam fluid is regarded as an ideal gas and the phase change is not considered, and a simplified model of the ideal gas state equation is introduced.

[0113] P i =ρ i R g,i T i

[0114] In the formula, R g,i is the gas constant, obtained according to IAPWS-IF97.

[0115] At the same time, the temperature change during steam transmission is ignored, and the average temperature of the steam network inlet and outlet is used for calculation. Based on the above two assumptions, the steam network transmission dynamic model is solved.

[0116] Step S2, establish a generalized energy storage model and calculate the energy storage characteristic parameters of the steam network:

[0117] Step S21, establish a generalized energy storage model. Compare the steam network energy storage to a generalized energy storage device, and use real-time storage / discharge rate, real-time storage / discharge amount, real-time total storage amount, maximum / minimum storage amount, required storage amount, and initial storage amount to describe the storage and discharge characteristics of the generalized energy storage model;

[0118] Step S22, based on the steam network transport dynamics model solution result of step S1, calculate the energy storage characteristic parameters of the generalized energy storage model. Since the temperature change of steam is ignored, the calculation method of its energy storage characteristic parameters is similar to that of gas fluids.

[0119] The real-time storage / discharge rate describes the real-time supply-demand imbalance. When supply exceeds demand, the real-time storage / discharge rate is positive, indicating that the generalized energy storage model is storing energy; when supply is less than demand, the real-time storage / discharge rate is negative, indicating that the generalized energy storage model is discharging energy.

[0120] S rt (t) = μ in (t)-μ out (t)

[0121] In the formula, S rt (t) is the real-time energy storage / discharge rate; μ in (t), μ out (t) are the energy of fluid injected and outflowed at time t.

[0122] Real-time storage / discharge energy describes the fluctuation of the generalized energy storage model around the initial storage energy during operation. The initial storage energy is the energy stored in the network at the initial point of the generalized energy storage model. The maximum and minimum storage energy describe the upper and lower limits of the generalized energy storage model, which together constitute the maximum storage capacity of the steam network and the constraints of real-time storage / discharge energy.

[0123]

[0124] In the formula, is the real-time storage / release of energy; dt is the time step; For maximum energy storage; is the minimum stored energy; For initial energy storage; is the real-time total storage energy; S max is the maximum energy storage capacity. The real-time energy storage / discharge rate in the case is as follows: Figure 3As shown, C / DF describes the real-time storage / discharge rate, N1 and N65 are Figure 2 The two steam heat source node outputs in , S1 and S2 are working condition 1 and working condition 2 respectively.

[0125] The maximum / minimum storage capacity of the steam network is described as

[0126]

[0127] In the formula, are the maximum pressures at the inlet and outlet of the generalized energy storage model, respectively; are the minimum pressures at the inlet and outlet of the generalized energy storage model; M i is the area of ​​the ith pipe, m 2 ; L i is the length of the i-th pipe, m; is the average temperature of the ith pipe, K; is the average density of the ith pipe, kg / m 3 ; np is the number of pipes. The maximum and minimum heat storage of the steam network in this case are 18949.98 kg and 11509.68 kg respectively.

[0128] The required storage capacity describes the energy that the generalized energy storage model must store in order to meet the supply on the demand side during operation. s is the total steam supply curve, Q c is the total steam demand curve, and the storage capacity of the generalized energy storage model is described as the integral of the supply and demand difference

[0129]

[0130] In the formula, ΔS d (t) is the energy storage curve. Then the required storage energy can be described as

[0131] S e =QA-QB

[0132] Where QA and QB are the highest and lowest points of the energy storage curve respectively.

[0133] With a scheduling cycle of 0.5 hours, the required heat storage capacity of the steam system in this case is 42.25 kg.

[0134] Step S3, establishing a quantitative evaluation model for energy storage characteristics of the steam transmission network to evaluate its energy storage capacity and utilization rate:

[0135] A quantitative evaluation model for the energy storage characteristics of steam transmission networks is established, including two evaluation indicators: satisfaction and utilization. Satisfaction refers to the satisfaction of the maximum energy storage capacity of the generalized energy storage model with the system scheduling requirements. It is used to evaluate the energy storage potential of a specific generalized energy storage model and its storage and discharge redundancy during the scheduling process.

[0136]

[0137] In the formula, χ is the satisfaction degree. According to the required heat storage and the maximum / minimum heat storage, the satisfaction degree in this case can be calculated to be 1.

[0138] Comprehensive utilization rate evaluates the utilization of the energy storage capacity of the generalized energy storage model by the system dispatch strategy during actual operation. First, calculate the positive utilization rate and negative utilization rate.

[0139]

[0140] Where η + is a positive utilization rate; η - is a negative utilization rate. Figure 4 shown.

[0141] Secondly, calculate the maximum and average of positive and negative utilization

[0142]

[0143]

[0144] In the formula, t d is the scheduling period; is the maximum positive utilization; is the maximum negative utilization; is the average positive utilization rate; is the average negative utilization.

[0145] Use the expert evaluation method to comprehensively evaluate the utilization rate of the generalized energy storage model and calculate the comprehensive utilization rate index

[0146]

[0147]

[0148] Where, η is the comprehensive utilization rate; w k is the weight of the kth item utilization; η k is the kth item utilization. η1 is the maximum value of positive utilization; η2 is the average value of positive utilization; η3 is the maximum value of negative utilization; η4 is the average value of negative utilization. Among them, the weight is given by the expert evaluation method.

[0149] Among them, in operating condition 1, the maximum positive utilization rate is 0.15%, the maximum negative utilization rate is -42.73%, the average positive utilization rate is 0.01%, and the average negative utilization rate is -14.59%; in operating condition 2, the maximum positive utilization rate is 2.63%, the maximum negative utilization rate is -11.15%, the average positive utilization rate is 0.54%, and the average negative utilization rate is -4.25%. The weights of each utilization rate are determined by the expert evaluation method as 0.33, 0.33, 0.02, and 0.02 respectively. The comprehensive utilization rate of operating condition 1 is 1.20%, and the comprehensive utilization rate of operating condition 2 is 1.35%. This shows that the comprehensive utilization rate of operating condition 2 is higher, and the energy storage capacity of the steam network is more fully utilized. Combined with Figure 3 At 2800s, there is a strong fluctuation on the heat source side but it is not reflected on the user side. This is because the steam network uses the energy storage capacity to absorb the benefits generated by the fluctuation on the source side, which confirms the conclusion that the comprehensive utilization rate of operating condition 2 is higher.

[0150] The method of the present invention quantitatively evaluates the energy storage capacity and energy storage utilization rate of the fluid transportation network by establishing a generalized energy storage model and energy storage evaluation system of the fluid transportation network, providing a model and constraint basis for the fluid transportation network to participate in the scheduling optimization of the integrated energy system, thereby increasing the regulation flexibility of the integrated energy system.

Claims

1. A method for quantifying dynamic energy storage characteristics of multi-energy networks in an integrated energy system, characterized in that: The following steps are involved: Step S1, establishing and solving a fluid network dynamic model containing a topological structure according to the mass, momentum and energy conservation equations; Step S2, establishing a generalized energy storage model and calculating energy storage characteristic parameters of the fluid network; Step S3, establishing a method for quantifying the energy storage characteristics of a fluid transport network, and using quantitative indicators to evaluate its energy storage capacity and utilization rate; Step S4, using the established fluid transport network energy storage characteristic quantification method to evaluate different transport networks for the same fluid or different operating conditions of the same transport network; In the step S1: Step S11: Establishing a fluid transport dynamics model in: Where, the subscript i represents energy flow i, which includes natural gas, compressed air, hot water, cold water, and steam; ρ i is the density, kg / m 3 ;v i is the speed, m / s; P i is the pressure, MPa; u i is the specific internal energy, J / kg; g i is the acceleration due to gravity, m / s 2 θ i is the pipeline inclination angle, °; λ i D is the drag coefficient; i is the pipe diameter, m; K i is the heat transfer coefficient, W / (m 2 ·K); T i is the fluid temperature, K; T i,r is the ambient temperature, K; For gas energy flows, including natural gas and compressed air, the gas temperature does not change during the transportation process, and the mass and momentum equations are combined to describe the gas energy flow transportation process; for liquid energy flows, including hot water and cold water, the liquid density does not change during the transportation process, and the momentum and energy equations are combined to describe the liquid energy flow transportation process; for steam, its density and temperature will change during the transportation process due to the influence of the source side supply and the environment, and the mass, momentum, and energy equations need to be combined to describe its transportation process; Step S12: Establishing a fluid network transport dynamics model According to graph theory, the node-branch matrix is ​​defined to describe the fluid topology. In the formula, A i is the node-branch association matrix of energy flow i; n is the number of nodes; m is the number of branches; a nm is the correlation coefficient between node n and branch m; At the same time, the fluid network constraints of energy flow i are established For natural gas and compressed air, for any node j in the fluid network of energy flow i, establish the flow balance equation ∑G i,j (t)+∑G o,j (t)=0 Where: ∑G i,j (t) is the mass flow rate flowing into node j at time t, kg / s; ∑G o,j (t) is the mass flow rate out of node j at time t, kg / s; For hot water and cold water, the node energy balance equation is ∑E i,j (t)+∑E o,j (t) = 0 Where: E i,j (t) is the energy flowing into node j, J; E o,j (t) is the energy flowing out of node j, J; For steam, the network constraints should include both flow balance and energy balance; Combined with the formula in step S11, a fluid network transport dynamics model with a topological structure can be established to describe the fluid transport process; Step S13, to simplify the calculation, natural gas, compressed air and steam are regarded as ideal gases and phase change is not considered, and a simplified model of the ideal gas state equation is introduced; according to the fluid characteristics, ordinary differential equations, partial differential equations or finite difference methods are selected to solve the fluid network transport dynamics model to obtain the distribution of fluid density, velocity and temperature in time and space.

2. According to claim 1, a method for quantifying dynamic energy storage characteristics of a multi-energy network of an integrated energy system is characterized in that: In the step S2: Step S21, establishing a generalized energy storage model; comparing the fluid network energy storage to a generalized energy storage device, using real-time storage / discharge rate, real-time storage / discharge amount, real-time total storage amount, maximum / minimum storage amount, required storage amount, and initial storage amount to describe the storage and discharge characteristics of the generalized energy storage model; Among them, for gas energy flow, including natural gas and compressed air, its storage energy is the gas volume; for liquid energy flow, including hot water and cold water, its storage energy is calculated by liquid temperature and flow rate; for steam, its storage energy is calculated by temperature and flow rate; Step S22, calculating energy storage characteristic parameters of the generalized energy storage model based on the solution result of the fluid network transport dynamics model in step S1; The real-time storage / discharge rate describes the real-time supply-demand imbalance; when supply exceeds demand, the real-time storage / discharge rate is positive, indicating that the generalized energy storage model is storing energy; when supply is less than demand, the real-time storage / discharge rate is negative, indicating that the generalized energy storage model is discharging energy; S rt (t)=μ in (t)-m out (t) In the formula, S rt (t) is the real-time energy storage / discharge rate; μ in (t), μ out (t) are the energy of fluid injected and outflowed at time t; Real-time storage / discharge energy describes the fluctuation of the generalized energy storage model around the initial storage energy during operation. The initial storage energy is the energy stored in the network at the initial point of scheduling of the generalized energy storage model. The maximum and minimum storage energy describe the upper and lower limits of the energy storage of the generalized energy storage model, which together constitute the maximum energy storage capacity of the fluid network and the constraints of real-time storage / discharge energy. In the formula, is the real-time storage / release of energy; dt is the time step; For maximum energy storage; is the minimum stored energy; For initial energy storage; is the real-time total storage energy; S max is the maximum energy storage capacity; For gaseous fluids, the maximum / minimum storage energy is described as In the formula, R g,i is the gas constant; are the maximum pressures at the inlet and outlet of the generalized energy storage model, respectively; are the minimum pressures at the inlet and outlet of the generalized energy storage model; M i is the area of ​​the ith pipe, m 2 ; L i is the length of the i-th pipeline, m; T is the gas temperature, K; is the average density of the ith pipe, kg / m 3 ; np is the number of pipelines; For liquid fluids, the maximum / minimum storage energy is described as In the formula, is the average specific heat capacity, J / (kg·K); G is the flow rate, kg / s; are the highest and lowest temperatures of the water supply, K; are the highest and lowest temperatures of return water, K; For steam fluid, the maximum / minimum energy storage is described as The required storage capacity describes the energy that the generalized energy storage model must store to meet the supply on the demand side during operation; Q s is the total energy supply curve, Q c is the total energy demand curve, and the storage capacity of the generalized energy storage model is described as the integral of the supply and demand difference In the formula, ΔS d (t) is the energy storage curve; then the energy storage must be described as S e =QA-QB In the formula, QA and QB are the highest and lowest points of the energy storage curve respectively; There are two types of simplified calculations for the dynamic model of the steam transport network, including ignoring changes in steam temperature and ignoring changes in steam density. For the simplified solution that ignores changes in steam temperature, the calculation method for the heat storage and release characteristics of the generalized energy storage model is the same as that for gas energy flow. For the simplified solution that ignores changes in steam density, the calculation method for the heat storage and release characteristics of the generalized energy storage model is the same as that for liquid energy flow.

3. According to claim 1, a method for quantifying dynamic energy storage characteristics of a multi-energy network of an integrated energy system is characterized in that: In the step S3: A quantitative model of energy storage characteristics of fluid transport networks is established, including two evaluation indicators: satisfaction and comprehensive utilization rate. Satisfaction refers to the satisfaction of the maximum energy storage capacity of the generalized energy storage model with the system scheduling requirements. It is used to evaluate the energy storage potential of a specific generalized energy storage model and its storage and discharge energy redundancy during the scheduling process. In the formula, χ is the satisfaction degree; Comprehensive utilization rate evaluates the utilization of the energy storage capacity of the generalized energy storage model by the system dispatch strategy during actual operation; first calculate the positive utilization rate and negative utilization rate Where η + is a positive utilization rate; η - Negative utilization; Secondly, calculate the maximum and average of positive and negative utilization Where, t d is the scheduling period; is the maximum value of positive utilization; is the maximum value of negative utilization; is the average value of positive utilization; is the maximum value of negative utilization; Use the expert evaluation method to comprehensively evaluate the utilization rate of the generalized energy storage model and calculate the comprehensive utilization rate index Where, η is the comprehensive utilization rate; w k is the weight of the kth item utilization; η k is the utilization rate of the kth item; η1 is the maximum value of positive utilization; η2 is the average value of positive utilization; η3 is the maximum value of negative utilization; η4 is the average value of negative utilization; among them, the weight is given by the expert evaluation method.

4. According to claim 1, a method for quantifying dynamic energy storage characteristics of a multi-energy network of an integrated energy system is characterized in that: In the step S4: Step S41, input different transmission networks of the same energy flow, and calculate the satisfaction of multiple transmission networks according to steps S1-S3; the satisfaction can be used to evaluate the network planning of different transmission networks of the same energy flow, and can also be used to evaluate the planning scheme of the energy flow transmission network; the greater the satisfaction, the more the generalized energy storage model can meet the energy storage and release requirements in the scheduling strategy, that is, the design of the transmission network is more matched with the actual operation scheduling; when the satisfaction is less than 1, it means that the generalized energy storage model is not enough to support the scheduling requirements of the system, and additional energy storage equipment needs to be configured; under the same economic conditions, the higher the satisfaction, the more reasonable the network planning; Step S42, input different operating conditions of the same energy flow and the same transmission network, and calculate the comprehensive utilization rate under different operating conditions according to steps S1-S3 to evaluate the utilization of the energy storage capacity of the transmission network under different operating conditions and their scheduling schemes; the condition with a high comprehensive utilization rate indicates that the generalized energy storage model is deeply involved in the scheduling, its energy storage capacity is more fully utilized, and the scheduling strategy makes more full use of the design configuration of the generalized energy storage model.

5. A system for quantitatively evaluating the energy storage characteristics of a comprehensive energy system transmission network, which uses the method according to any one of claims 1 to 4 to quantitatively evaluate the energy storage characteristics of a comprehensive energy system transmission network, characterized in that: The system includes a data processing module, a fluid network transport dynamics model modeling and solution module, a generalized energy storage model modeling and calculation module, and an energy storage characteristic quantitative evaluation module; the above modules are respectively encapsulated to establish a data transmission channel; The data processing module processes the input integrated energy system fluid transport network parameters and operation data, and transmits the processed data to the fluid network transport dynamic model modeling and solution module; The fluid network transport dynamic model modeling and solution module establishes a fluid network dynamic model with a topological structure according to the fluid characteristics, simplifies the mass, momentum and energy equations, selects a solution method to solve the fluid network dynamic model, and transmits the spatiotemporal distribution data of density, velocity and temperature to the generalized energy storage model calculation module; The generalized energy storage model modeling and calculation module is used to establish a generalized energy storage model, calculate the energy storage and release characteristics of the fluid network, calculate six key parameters including real-time energy storage / release rate, real-time energy storage / release amount, real-time total energy storage, maximum / minimum energy storage, required energy storage, and initial energy storage, and transmit the calculation results to the energy storage characteristic quantitative evaluation module; The energy storage characteristic quantitative evaluation module calculates two indicators, namely, satisfaction and comprehensive utilization rate, and evaluates different transport networks of the same fluid from the perspective of energy storage potential, and evaluates and analyzes different operating conditions of the same transport network from the perspective of comprehensive energy storage utilization rate, and obtains quantitative evaluation results respectively.

Images