Digital twinning method and device for energy loss and dynamic response of steam pipe network and computer program product

Abstract

The invention discloses a digital twinning method and device for energy loss and dynamic response of a steam pipe network and a computer program product, and the method comprises the following steps: S1, constructing a pipe network model according to the structural parameters of the steam pipe network; s2, acquiring current steam pipe network measuring point data, wherein the steam pipe network measuring point data comprises pressure and temperature of a gas supply end and mass flow of a user end; s3, parameters including the enthalpy value and the pressure difference of steam are obtained according to an IAPWS-IF97 formula; s4, the steam operation pressure and the specific enthalpy of adjacent nodes are solved according to node distribution of the steam pipe network; s5, the flow between the nodes is obtained according to the obtained pressure and specific enthalpy of the adjacent nodes; and S6, solving parameters of other nodes by analogy to obtain temperature and pressure of all nodes and flow parameters among the nodes. Through field experiment verification, the result shows that the method can effectively improve the calculation precision of the steam quality of the steam pipe network node, and is suitable for simulation research of most steam pipe networks under different working conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of pipeline network steam quality prediction, and specifically relates to a digital twin method device and computer program product for steam pipeline network energy loss and dynamic response. Background Art

[0002] Steam plays an indispensable role in the heating of Chinese residents and industrial production. In order to achieve environmental protection goals, my country has introduced a number of policies on the construction of heating pipeline networks, and cogeneration is widely regarded as an effective measure for energy conservation and environmental protection. Domestic and foreign scholars have provided multi-faceted research on model construction and model calculation of steam district heating systems. The main technical means of steam network simulation calculation is to use fluid mechanics equations to establish the geometry and boundary conditions of the pipeline network, and to establish a pipeline network fluid calculation model based on the fluid properties and flow state, so as to obtain the changes in parameters such as fluid velocity, temperature, and pressure inside the pipeline. Many studies have shown that establishing a simulation calculation model of the pipeline network to predict, optimize and control the internal fluid operating parameters of the steam pipeline network can provide strong support for the efficient and stable operation of the pipeline network.

[0003] Due to the discontinuous use of steam, it is easy to cause water hammer and steam hammer in the pipeline, thus causing damage to the pipeline. That is to say, when the valve is opened and closed instantly in the heating pipeline network, or when there is a sudden flow change, the pressure fluctuation of the pipeline system will be too large. At this time, it is necessary to open the pressure regulating valve to release some steam to make the pressure drop back to a safe range.

[0004] At present, some scholars have studied the dynamic hydraulic characteristics of the heating network. You Shijun et al. established a non-steady-state hydraulic model of a single pipeline, proposed a solution method, and analyzed the delayed response characteristics of different pipeline parameters to the fluid. Yang Yi et al. established a mathematical model of a simple pipeline and performed dynamic simulation, reducing the pressure fluctuations during the operation of the pipeline network by adjusting the PID parameters. Zhao Fengmin et al. predicted the pressure of the steam network, which has certain guiding significance for the actual production of the enterprise, but has not been applied in practice. It can be seen that studying the dynamic response characteristics of the steam network can help predict the dynamic response behavior of the network. On the one hand, it can reduce the incidence of production accidents, and on the other hand, it can also optimize the design of the network system, which is of great significance to the safety and energy-saving regulation of the network.

[0005] However, the steam network has many nodes and a complex structure. Steam presents a variety of flow patterns, and the working conditions of the steam network change in real time over time, such as changes in steam load and adjustments to the network configuration. This complexity makes it difficult to accurately simulate the quality of steam in the network. In addition, the long-term operation of the steam network will lead to problems such as pipeline corrosion and scaling of the pipe wall, making it difficult to accurately model the pipeline, which has long been a major problem in network simulation. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a digital twin method device and computer program product for energy loss and dynamic response of steam pipeline network, which simulates steam quality parameters and dynamic response states of different nodes of the pipeline network by constructing steam pipeline network structure model, flow and energy transfer calculation simulation model. The present invention provides an effective means to deal with sudden situations of pipeline network and improve the operation and scheduling safety of pipeline network.

[0007] The technical solution adopted in the present invention is:

[0008] A digital twin method for energy loss and dynamic response of a steam pipeline network, characterized in that the method comprises the following steps:

[0009] S1. Constructing a pipe network model according to the structural parameters of the steam pipe network; the structural parameters include user quantity parameters, steam flow parameters and pipe parameters;

[0010] S2. Acquire the current steam pipe network measurement point data, wherein the steam pipe network measurement point data includes the pressure and temperature at the gas supply end and the mass flow at the user end;

[0011] S3. Obtain parameters including steam enthalpy and pressure difference according to the IAPWS-IF97 formula;

[0012] S4. Calculate the steam operating pressure and specific enthalpy of adjacent nodes according to the node distribution of the steam network;

[0013] S5. Calculate the flow rate between nodes based on the pressure and specific enthalpy of adjacent nodes;

[0014] S6. Calculate other node parameters in the same way to obtain the temperature and pressure of all nodes and the flow parameters between nodes.

[0015] Furthermore, in step S1, key parameters of the steam network are obtained, including pipelines, valves and fluid component accessories, as well as pipeline parameters between various components, including length, diameter, variable diameter area and drop height.

[0016] Furthermore, a topological structure is established for the steam network, including heat source nodes, gas consumption nodes and network bifurcation nodes.

[0017] Furthermore, the node temperature T i , pressure p i Flow G i and specific enthalpy h i The calculation method is as follows:

[0018] 1) Build a simulation model and set structural parameters;

[0019] 2) Get t = t oBoundary conditions

[0020] 3) Obtain the initial values ​​of the first-order differential equations through IAPWS-IF97;

[0021] 4) Solve the first-order differential equations and update the pressure and specific enthalpy of all nodes;

[0022] 5) Calculate the traffic between nodes;

[0023] 6) Update other parameters

[0024] 7) Determine whether the calculation is completed and output the temperature T i , pressure p i Flow G i and specific enthalpy h i , otherwise return to step 3);

[0025] in, They refer to: the flow rate, temperature and pressure of node i at the initial moment; They respectively refer to: pressure, flow rate, specific enthalpy and calculated i-node temperature at time t.

[0026] Furthermore, the method for establishing the simulation model is as follows:

[0027] 1) The pipe network is divided into several basins. The fluid movement within each basin can be expressed by three conservation laws:

[0028] Equation (1) is the law of mass conservation, which is as follows:

[0029]

[0030] Where: i is the steam density, kg / m 3 ; V i is the volume of node i, m 3 ; G ij is the mass flow rate between nodes, kg / s; T c is the leakage term between pipe networks; E ij Indicates the connectivity between nodes, 1 indicates flow to j, -1 indicates flow from i to j, and 0 indicates no connectivity;

[0031] Equation (2) is the conservation of momentum, which is as follows:

[0032]

[0033] Where: I ij =L ij / A ij , represents the inertia coefficient of the pipeline, where L ijis the distance between nodes i and j; A ij is the average cross-sectional area between nodes i and j, m 2 ;p i , p j is the pressure at node i, j, Pa; H ij Represents the height potential difference between nodes, Pa; R ij represents the resistance coefficient of the element between nodes i and j;

[0034] Equation (3) is the energy conservation law, which is as follows:

[0035]

[0036] Among them, ρ i is the steam density, kg / m 3 ; V i is the volume of node i, m 3 ; G ij is the mass flow rate between nodes, kg / s; h ij is the pressure loss along the process between nodes; u i is the specific internal energy, kJ / kg; h i ,h j is the specific enthalpy of node i, j, kJ / kg; Q ij is the pipeline heat loss between nodes i and j, kJ / s; and They represent the one-way flow relationship between node i and node j. When the fluid flows from node j to node i, otherwise When the fluid flows from node j to node i otherwise And there is

[0037] 2) Ignore the time term of equation (2) and obtain the calculation formula of flow rate and pressure difference. Ignore the leakage of the leaking pipeline and substitute equation (2) into the continuity equation (1) to obtain:

[0038]

[0039] 3) According to the thermodynamic properties of water and steam, density is related to pressure and specific enthalpy, that is, ρ = ρ (p, h), and the density change is expressed as:

[0040]

[0041] 4) Using the IAPWS-IF97 formula, it can be calculated Substituting into formula (9) can be transformed into:

[0042]

[0043] The mass conservation equation is expressed as:

[0044]

[0045] In the formula,

[0046]

[0047] 5) The energy equation (3) is transformed by the thermodynamic property ρu=ρh-p, and the effect of driving work is neglected. The left side of the energy equation is expanded to obtain:

[0048]

[0049] So the energy equation is expressed as:

[0050]

[0051] In the formula,

[0052]

[0053] Equation (12) and equation (14) form a nonlinear equation system, in which both the resistance loss and the heat dissipation loss can be calculated. The equation system has only two unknown variables, and the simultaneous equations can be solved:

[0054]

[0055] Furthermore, the heat loss Q between the i and j nodes of the steam network is ij It is expressed as:

[0056] Q ij =K△t m L ij (4)

[0057] Among them, △t m is the average temperature difference between the steam and the external environment of the pipe section, °C; L ij is the pipe length between node i and node j, m; K is the heat transfer coefficient per unit length of the pipe section, W / (m·K), and the calculation expression is as follows:

[0058]

[0059] Among them, h1 and h2 are the surface heat transfer coefficients of the inner and outer walls of the pipe section, W / (m 2 ·K); n is the number of steam pipe insulation layers; λ i is the thermal conductivity of the i-th layer of insulation material, W / (m·K); r i is the inner diameter of the i-th insulation layer, m; r in , r out To calculate the inner and outer diameters of the pipe section, m.

[0060] Furthermore, the pressure loss along the process h ij Including local loss and along-the-way loss, the expression formula is:

[0061]

[0062] Among them, the first item on the right side is the resistance loss of steam along the pipe section, Pa; the second item is the local resistance loss, Pa; where: L is the pipe length, d is the diameter, n is the medium flow rate, m / s; λ is the friction resistance coefficient, ε n is the local resistance coefficient of different resistance components;

[0063] The empirical formula for calculating the pipeline resistance coefficient proposed by Auletta-Schule is as follows:

[0064]

[0065] in, is the relative roughness of the pipeline; Re is the Reynolds number of the fluid.

[0066] A computer device comprises a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the above-mentioned method.

[0067] A computer-readable storage medium stores a computer program or instruction thereon, wherein the computer program or instruction implements the above-mentioned method when executed by a processor.

[0068] A computer program product comprises a computer program or an instruction, wherein the computer program or the instruction implements the above-mentioned method when executed by a processor.

[0069] Compared with the prior art, the present invention has the following beneficial effects:

[0070] 1. Real-time monitoring and prediction of the present invention: Digital twin technology can monitor the status of the steam pipeline network in real time and predict the energy loss and dynamic response of the system, which helps to promptly detect abnormal conditions in the system and take corresponding measures, thereby improving the safety and reliability of system operation.

[0071] 2. The present invention optimizes the operation strategy: By simulating different operating conditions and strategies, the steam pipeline network digital twin method can evaluate the impact of various strategies on the energy loss and dynamic response of the steam pipeline network, thereby guiding the operation management of the optimization system and improving energy efficiency.

[0072] 3. Fault diagnosis and prevention of the present invention: The digital twin model can accurately reflect the various complex processes and potential faults in the operation of the steam pipeline network, effectively diagnose and prevent faults, predict the maintenance needs of equipment and the best maintenance time, thereby achieving preventive maintenance, reducing maintenance costs, reducing downtime, and extending equipment life.

[0073] 4. The present invention has been verified through field experiments, and the results show that this method can effectively improve the calculation accuracy of steam quality at the nodes of the steam network, and is suitable for simulation research of most steam networks under different working conditions. The simulation calculation error of the node pressure is within 2%, and the temperature error is about 10%. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 Schematic diagram of the steam pipe network structure.

[0075] Figure 2 This is the flow chart of the water thermal calculation of the steam network.

[0076] Figure 3 This is a comparison chart of the model calculation and on-site pressure values ​​for implementation case 1.

[0077] Figure 4 This is a comparison chart of the model calculation and on-site temperature values ​​for implementation case 1.

[0078] Figure 5 This is the pressure response fluctuation diagram of other nodes when the pressure changes in case 2.

[0079] Figure 6 This is the pressure response fluctuation diagram of other nodes when the flow changes in implementation case 3. DETAILED DESCRIPTION

[0080] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0081] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0082] The present invention will be described in detail below in conjunction with exemplary embodiments with reference to the accompanying drawings.

[0083] refer to Figure 1 to Figure 2The digital twin method of energy loss and dynamic response of a steam pipeline network of the present invention first constructs a pipeline network model according to the structural parameters of the pipeline network, and the structural parameters include user quantity parameters, steam flow parameters, and pipeline parameters; then obtains the current pipeline network measurement point data, including the pressure and temperature at the gas supply end and the mass flow at the user end; then obtains the steam enthalpy value, pressure difference and other parameters according to the IF-97 formula; then calculates the steam operating pressure and specific enthalpy of adjacent nodes according to the node distribution of the pipeline network; then calculates the flow rate between nodes based on the pressure and specific enthalpy of adjacent nodes; and calculates other node parameters in this way to obtain the temperature pressure of all nodes and the flow rate parameters between nodes. The specific operation steps are as follows:

[0084] Step S1: Obtain the pipeline parameters of the steam network and draw the network node diagram.

[0085] Obtain key parameters of the steam network, including fluid components such as pipelines, valves, accessories, and pipeline parameters between various components, including length, diameter, variable diameter area, drop height, etc.

[0086] like Figure 1 As shown in Figure 1, a topological structure is established for the steam network, including heat source nodes, gas consumption nodes, and network bifurcation nodes. Among them, 0 is a heat source node, 13-20 are gas consumption nodes, and 1-12 are network bifurcation nodes. The pipeline parameters are detailed in Table 1.

[0087] Table 1 Steam network structural parameters

[0088]

[0089] Step S2: Establishment of steam network flow and energy transfer model

[0090] 2.1 Conservation equations for fluid networks

[0091] The pipe network is divided into several basins, and the fluid movement within each basin can be expressed by three major conservation laws:

[0092] Equation (1) mass conservation:

[0093]

[0094] Where: ρ(ρ i ) is the steam density, kg / m 3 ; V i is the volume of node i, m 3 ; G ij is the mass flow rate between nodes, kg / s; T c is the leakage term between pipe networks; E ij Indicates the connectivity between nodes, 1 indicates flow to j, -1 indicates flow from i to j, and 0 indicates no connectivity;

[0095] Equation (2) Momentum conservation:

[0096]

[0097] Where: I ij =L ij / A ij Indicates the inertia coefficient of the pipeline, L ij , A ij ;p i , p j is the pressure at node i, j, Pa; H ij Represents the height potential difference between nodes, Pa; R ij represents the resistance coefficient of the element between nodes i and j;

[0098] Equation (3) Energy conservation:

[0099]

[0100] Among them, ρ(ρ i ) is the steam density, kg / m 3 ; V i is the volume of node i, m 3 ; G ij is the mass flow rate between nodes, kg / s; h ij is the pressure loss along the process between nodes; u i is the specific internal energy, kJ / kg; h i ,h j is the specific enthalpy of node i, j, kJ / kg; Q ij is the heat dissipation flow between nodes i and j, kJ / s; and They represent the one-way flow relationship between node i and node j. When the fluid flows from node j to node i, otherwise When the fluid flows from node j to node i otherwise And there is

[0101] 2.2 Calculation of pipeline heat loss

[0102] The pipeline heat loss of the steam network can be expressed as:

[0103] Q ij =KΔt m L ij (4)

[0104] Among them, △t m is the average temperature difference between the steam and the external environment of the pipe section, °C; L ijis the length of the pipe between node i and node j, m; K is the heat transfer coefficient per unit length of the pipe section, W / (m·K), and the calculation expression is:

[0105]

[0106] Among them, h1 and h2 are the surface heat transfer coefficients of the inner and outer walls of the pipe section, W / (m 2 ·K); n is the number of steam pipe insulation layers; λ i is the thermal conductivity of the i-th layer of insulation material, W / (m·K); r i is the inner diameter of the i-th insulation layer, m; r in , r out To calculate the inner and outer diameters of the pipe section, m.

[0107] 2.3 Pipeline pressure loss

[0108] The pressure loss along the pipeline includes local loss and along-the-way loss, which can be expressed as:

[0109]

[0110] Among them, the first item on the right side is the resistance loss of steam along the pipe section, Pa; the second item is the local resistance loss, Pa; where: L is the pipe length, d is the diameter, n is the medium flow rate, m / s; λ is the friction resistance coefficient, ε n is the local resistance coefficient of different resistance components.

[0111] In actual engineering, the empirical formula for calculating the pipeline resistance coefficient proposed by Auletta-Schule is often used:

[0112]

[0113] is the relative roughness of the pipeline; Re is the Reynolds number of the fluid.

[0114] Step S3: Model Solution

[0115] like Figure 2 As shown, the node temperature T i , pressure p i Flow G i and specific enthalpy h i The calculation method is as follows:

[0116] 1) Build a simulation model and set structural parameters;

[0117] 2) Get t = t o Boundary conditions

[0118] 3) Obtain the initial values ​​of the first-order differential equations through IAPWS-IF97;

[0119] 4) Solve the first-order differential equations and update the pressure and specific enthalpy;

[0120] 5) Calculate the traffic between nodes;

[0121] 6) Update other parameters

[0122] 7) Determine whether the calculation is completed and output the temperature T i , pressure p i Flow G i and specific enthalpy h i , otherwise return to step 3).

[0123] The simulation model is established as follows:

[0124] 1) Solve the parameters of all nodes in the pipe network at the same time. The three major equations are combined, and the steam state equation is used to update the steam properties, so that the pressure and specific enthalpy of each node can be solved simultaneously within one step time. Ignore the time term of equation (2), and obtain the calculation formula of flow rate and pressure difference. Ignore the leakage of the leaking pipeline, and substitute equation (2) into the continuity equation (1) to obtain:

[0125]

[0126] 2) According to the thermodynamic properties of water and steam, density is related to pressure and specific enthalpy, that is, ρ = ρ (p, h), and the density change is expressed as:

[0127]

[0128] 3) Using the IAPWS-IF97 formula, it can be calculated Substituting into formula (9) can be transformed into:

[0129]

[0130] The mass conservation equation is expressed as:

[0131]

[0132] In the formula,

[0133]

[0134] 4) The energy equation (3) is transformed according to the thermodynamic property ρu=ρh-p, and the effect of driving work is ignored. The left side of the energy equation is expanded to obtain:

[0135]

[0136] So the energy equation is expressed as:

[0137]

[0138] In the formula,

[0139]

[0140] Equation (12) and equation (14) form a nonlinear equation system, in which both the resistance loss and the heat dissipation loss can be calculated. The equation system has only two unknown variables, and the simultaneous equations can be solved:

[0141]

[0142] The calculation equations of commonly used thermodynamic property parameters provided by IAPWS-IF97 are shown in Table 2.

[0143] Table 2 Calculation equations for commonly used thermodynamic property parameters in zone 2

[0144]

[0145]

[0146] Implementation Case 1

[0147] Taking the combined heat and power steam network of a thermal power plant as an example, when the heat source steam pressure is 1.268MPa, the temperature is 311.26℃, and the flow rate is 32.135t / h, the temperature and pressure parameters of each node of the steam network are calculated through the above process. Figure 3 , Figure 4 The calculation accuracy of node pressure is high, and the error is within 2%. The error of node 13 is 14.612%. After verification, the pressure instrument of this node has gradually degraded due to long-term use, and the measurement is inaccurate; the user temperature is consistent with the temperature drop trend along the pipeline network, and the error is about 10%.

[0148] Implementation Case 2

[0149] In order to simulate the replacement of different steam supply lines in a thermal power plant, the steam end parameters are kept unchanged, and the steam supply end pressure is increased rapidly from 1.257MPa to 1.280MPa within 2 seconds. The response speed of each user node is calculated. The results are as follows: Figure 5 shown.

[0150] From the response speed, we can see that the terminal nodes No. 13 and No. 20 responded almost simultaneously with the source end. The two nodes are closest to the steam supply end. Other farther users have a certain response delay, and the farthest node No. 16 responds the slowest. From the response fluctuation analysis, nodes No. 20, No. 13, and No. 19 show obvious pressure oscillations, while other nodes are relatively stable. Comprehensive analysis shows that all nodes in the case basically reach a steady state within 30 seconds. When the thermal power plant replaces the line, if the pressure regulating valves along lines 13, 20, and 19 are opened in advance, the pressure on the pipeline can be avoided from being too high. After 30 seconds, the pressure regulating valves can be closed after the lines are stable, which can effectively avoid steam waste.

[0151] Implementation Case 3

[0152] In order to simulate the impact of changes in user steam consumption on the pipeline network, other boundary parameters are kept unchanged and the flow rate at node 18 is reduced rapidly. The response results are as follows: Figure 6 .

[0153] From the analysis of response speed, when valve No. 18 is closed, the pressure in the pipeline network will rise rapidly and fluctuate. Node No. 18 responds first, followed by No. 17, No. 15 and No. 16; from the analysis of response fluctuation, nodes No. 18 and No. 17 are most affected, while the farthest nodes No. 19 and No. 20 do not show obvious pressure changes. Closing the valve will also cause pressure fluctuations in the pipeline network, so in this case, before closing the user flow valve, the pressure regulating valve of the user and the nearest user should be opened in advance, and closed in time to avoid losses.

[0154] The above is a description of the embodiments of the present invention. Through the above description of the disclosed embodiments, professionals and technicians in the field can implement or use the present invention. Various modifications to these embodiments will be apparent to professionals and technicians in the field. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown in this article, but will conform to the widest range consistent with the principles and novelties disclosed herein.

Claims

1. A digital twin method for steam network energy loss and dynamic response, characterized in that: The method comprises the following steps: S1. Constructing a pipe network model according to the structural parameters of the steam pipe network; the structural parameters include user quantity parameters, steam flow parameters and pipe parameters; S2. Acquire the current steam pipe network measurement point data, wherein the steam pipe network measurement point data includes the pressure and temperature at the gas supply end and the mass flow at the user end; S3. Obtain parameters including steam enthalpy and pressure difference according to the IAPWS-IF97 formula; S4. Calculate the steam operating pressure and specific enthalpy of adjacent nodes according to the node distribution of the steam network; S5. Calculate the flow rate between nodes based on the pressure and specific enthalpy of adjacent nodes; S6. Calculate other node parameters in the same way to obtain the temperature and pressure of all nodes and the flow parameters between nodes.

2. A digital twin method for steam network energy loss and dynamic response according to claim 1, characterized in that: In step S1, key parameters of the steam network are obtained, including pipelines, valves, and fluid component accessories, as well as pipeline parameters between various components, including length, diameter, variable diameter area, and drop height.

3. A digital twin method for steam network energy loss and dynamic response according to claim 2, characterized in that: A topological structure is established for the steam network, including heat source nodes, gas consumption nodes and network bifurcation nodes.

4. A digital twin method for steam network energy loss and dynamic response according to claim 1, characterized in that: The temperature of the node T i , pressure p i Flow G i and specific enthalpy h i The calculation method is as follows: 1) Build a simulation model and set structural parameters; 2) Get t = t o Boundary conditions 3) Obtain the initial values ​​of the first-order differential equations through IAPWS-IF97; 4) Solve the first-order differential equations and update the pressure and specific enthalpy of all nodes; 5) Calculate the traffic between nodes; 6) Update other parameters 7) Determine whether the calculation is completed and output the temperature T i , pressure p i Flow G i and specific enthalpy h i , otherwise return to step 3); in, They refer to: the flow rate, temperature and pressure of node i at the initial moment; They respectively refer to: pressure, flow rate, specific enthalpy and calculated i-node temperature at time t.

5. A digital twin method for steam network energy loss and dynamic response according to claim 4, characterized in that: The method for establishing the simulation model is as follows: 1) The pipe network is divided into several basins. The fluid movement within each basin can be expressed by three conservation laws: Equation (1) is the law of mass conservation, which is as follows: Where: i is the steam density, kg / m 3 ; V i is the volume of node i, m 3 ; G ij is the mass flow rate between nodes, kg / s; T c is the leakage term between pipe networks; E ij Indicates the connectivity between nodes, 1 indicates flow to j, -1 indicates flow from i to j, and 0 indicates no connectivity; Equation (2) is the conservation of momentum, which is as follows: Where: I ij =L ij / A ij , represents the inertia coefficient of the pipeline, where L ij is the distance between nodes i and j; A ij is the average cross-sectional area between nodes i and j, m 2 ;p i , p j is the pressure at node i, j, Pa; H ij Represents the height potential difference between nodes, Pa; R ij represents the resistance coefficient of the element between nodes i and j; Equation (3) is the energy conservation law, which is as follows: Among them, ρ i is the steam density, kg / m 3 ; V i is the volume of node i, m 3 ; G ij is the mass flow rate between nodes, kg / s; h ij is the pressure loss along the process between nodes; u i is the specific internal energy, kJ / kg; h i ,h j is the specific enthalpy of node i, j, kJ / kg; Q ij is the pipeline heat loss between nodes i and j, kJ / s; and They represent the one-way flow relationship between node i and node j. When the fluid flows from node j to node i otherwise When the fluid flows from node j to node i otherwise And there is 2) Ignore the time term of equation (2) and obtain the calculation formula of flow rate and pressure difference. Ignore the leakage of the leaking pipeline and substitute equation (2) into the continuity equation (1) to obtain: 3) According to the thermodynamic properties of water and steam, density is related to pressure and specific enthalpy, that is, ρ = ρ (p, h), and the density change is expressed as: 4) Using the IAPWS-IF97 formula, it can be calculated Substituting into formula (9) can be transformed into: The mass conservation equation is expressed as: In the formula, 5) The energy equation (3) is transformed by the thermodynamic property ρu=ρh-p, and the effect of driving work is ignored. The left side of the energy equation is expanded to obtain: So the energy equation is expressed as: In the formula, Equation (12) and equation (14) form a nonlinear equation system, in which both the resistance loss and the heat dissipation loss can be calculated. The equation system has only two unknown variables, and the simultaneous equations can be solved:

6. A digital twin method for steam network energy loss and dynamic response according to claim 5, characterized in that: Pipeline heat loss Q of steam network ij It is expressed as: Q ij =K△t m L ij (4) Among them, △t m is the average temperature difference between the steam and the external environment of the pipe section, °C; L ij is the pipe length between node i and node j, m; K is the heat transfer coefficient per unit length of the pipe section, W / (m·K), and the calculation expression is as follows: Among them, h1 and h2 are the surface heat transfer coefficients of the inner and outer walls of the pipe section, W / (m 2 ·K); n is the number of steam pipe insulation layers; λ i is the thermal conductivity of the i-th layer of insulation material, W / (m·K); r i is the inner diameter of the i-th insulation layer, m; r in , r out To calculate the inner and outer diameters of the pipe section, m.

7. A digital twin method for steam network energy loss and dynamic response according to claim 5, characterized in that: Pressure loss along the process h ij Including local loss and along-the-way loss, the expression formula is: Among them, the first item on the right side is the resistance loss of steam along the pipe section, Pa; the second item is the local resistance loss, Pa; where: L is the pipe length, d is the diameter, n is the medium flow rate, m / s; λ is the friction resistance coefficient, ε n is the local resistance coefficient of different resistance components; The empirical formula for calculating the pipeline resistance coefficient proposed by Auletta-Schule is as follows: in, is the relative roughness of the pipeline; Re is the Reynolds number of the fluid.

8. A computer device comprising a memory, a processor and a computer program stored in the memory, characterized in that: The processor executes the computer program to implement the method according to any one of claims 1 to 7.

9. A computer-readable storage medium having a computer program or instruction stored thereon, characterized in that: When the computer program or instruction is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

10. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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