CN115688340B - Method and system for solving dynamic simulation of natural gas transmission pipe network system - Google Patents

Abstract

The disclosure belongs to the technical field of natural gas operation control, and specifically relates to a solution method and system for dynamic simulation of a natural gas transmission pipeline network system, including: obtaining the topological structure of the natural gas transmission network, and constructing a dynamic partial differential equation of the gas transmission pipeline; Discretize and linearize the partial differential equations to obtain a system of linear equations; iteratively solve the obtained system of linear equations to obtain the pressure and mass flow at each grid node of the gas transmission network under the same time layer, and predict the gas transmission network. The node pressure and pipeline flow of the gas network are used to complete the dynamic simulation of the natural gas transmission pipeline network system.

Description

A solution method and system for dynamic simulation of natural gas transmission pipeline network system

technical field

The disclosure belongs to the technical field of natural operation control, and in particular relates to a solution method and system for dynamic simulation of a natural gas transmission pipeline network system.

Background technique

The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.

The gas transmission network is an important part of the natural gas system, and the key to the simulation of the natural gas system is the simulation of the gas dynamic flow process in the gas transmission network. By establishing a dynamic simulation model of the gas transmission network and solving it, it is possible to simulate the dynamic operation of the natural gas system under given conditions, and predict changes in state variables such as system node air pressure and pipeline flow in the future. The dynamic simulation results of the gas transmission network can provide a reference for the optimal operation of the natural gas system and provide a theoretical basis for engineering practice. In order for the model to be more effectively applied to the optimal operation research of the system, it is necessary to use a reasonable method to quickly and accurately solve the dynamic simulation model of the gas transmission network to improve the planning and operation efficiency. Otherwise, the solution speed is too slow and the accuracy is too low, and the model will fail. It will lose its practical application value.

According to the inventor's understanding, the solution of the dynamic partial differential equation model of the gas transmission network faces the following difficulties, which make it difficult to quickly and accurately simulate the natural gas system: the one-dimensional dynamic flow process of natural gas inside the pipeline is described by a set of partial differential The original differential equations of the gas pipeline dynamic simulation model are very complex, and the state parameters such as gas pressure, density, and flow rate are interrelated, and they are all functions of time and space. Simplification, but the partial differential equation itself is still difficult to solve directly and effectively; in addition, there are nonlinear terms in the equation system, the equations are highly complex and non-convex, and the nonlinear solution method requires a large amount of calculation and slow calculation speed. For a large-scale pipe network system with hundreds or even thousands of interconnected pipelines in actual engineering, the solution scheme of complex partial differential equations will lead to long calculation time, low solution efficiency, and the storage requirement of a large amount of data will also increase. lead to an increase in computational cost.

Contents of the invention

In order to solve the above problems, this disclosure proposes a solution method for the dynamic simulation of the natural gas transmission pipeline network system control system, based on the linearization and discretization grid method, the partial differential equation model describing the dynamic simulation of the gas transmission network is transformed into a linear Equation model, improve the speed of model solution, and ensure the accuracy through iterative solution. Compared with the traditional method, the proposed method improves the stability of the simulation solution, reduces the number of variables to be solved, and can achieve a good fitting of the dynamic process.

According to some embodiments, the first solution of the present disclosure provides a solution method for dynamic simulation of a natural gas transmission pipeline network system, which adopts the following technical solution:

A solution method for dynamic simulation of a natural gas transmission pipeline network system, comprising:

Obtain the topological structure of the natural gas transmission network, and construct the dynamic partial differential equation of the gas transmission pipeline;

Discretize and linearize the constructed partial differential equations to obtain a system of linear equations;

Iteratively solve the obtained linear equations, obtain the air pressure and mass flow at each grid node of the gas transmission network under the same time layer, predict the node air pressure and pipeline flow of the gas transmission network, and complete the natural gas transmission pipeline network system Dynamic simulation.

As a further technical limitation, identify the connection relationship between various natural gas pipelines, and count the load at the end of each pipeline; establish a partial differential equation model of the gas pipeline, and simplify it with general assumptions, the gas pressure p(t, x) and mass flow q(t,x) describe the gas pipeline partial differential equation model:

Among them, t represents time, x represents the distance along the axis of the pipe, p represents the air pressure, D represents the inner diameter of the pipe, A represents the cross-sectional area of the pipe, λ represents the friction coefficient of the pipe, Z represents the gas compression coefficient, R represents the gas constant, T Represents temperature, q represents mass flow.

As a further technical limitation, the space step and time step are selected, all the pipelines of the gas transmission network are divided into grids, and the partial differential equations are discretized and linearized;

In the steady state, the gas pressure in the pipeline does not change with time, the gas flow does not change with time and space, and the space partial derivative is discrete, and the calculation formula of the pipeline pressure under steady state conditions is obtained:

和/>

代表稳态时网格节点n和n-1处的气体压力，/>

表示稳态时第i根管道的质量流量；in,

and />

represents the gas pressure at grid nodes n and n-1 at steady state, />

Indicates the mass flow rate of the i-th pipe at steady state;

In dynamic mode, different discrete formats are used based on the different node types, that is, the different pipeline positions of the nodes:

For mesh nodes in the middle of the pipeline, the discretization format is as follows:

For the pipeline start node and pipeline end node, the following discrete formats are used:

To simplify the expression, define constants:

Among them, Δx represents a discrete space step, and Δt represents a discrete time step.

Further, set the variables that need to be solved iteratively, and establish an iterative variable matrix; for a pipeline, given the known quantity at the previous time and the air pressure distribution at this time, the flow distribution at this time is directly calculated, and the air pressure and the initial pressure of each branch pipeline are calculated. The end flow is used as the iterative solution variable, and the pressure variable matrix and flow variable matrix are established.

Further, based on the steady-state pressure formula and the given steady-state gas mass flow rate, the steady-state node pressure of each grid node is calculated as the initial state of the network dynamic simulation. By defining the grid point pressure and flow correction value, the node Air pressure error equation, node air pressure correction equation, flow error equation and flow correction equation, complete discretization and linearization of partial differential equations, and obtain linear equations.

As a further technical limitation, in the process of iterative solution, the nodal air pressure and mass flow at the previous moment are taken as the hypothetical values p ^* and q ^* of the variables to be obtained at this moment, which are the initial values of the iteration; through the nodal air pressure error equation and The flow error equation calculates the error, and judges the relationship between the calculated error and the allowable value. If the obtained error is less than the allowable value, the flow of the remaining nodes is calculated based on the air pressure and flow after iterative solution, and the natural gas pipeline is completed. Network system dynamic simulation solution.

Further, if the obtained error is not less than the allowable value, construct a linear correction equation group, solve it by matrix operation, obtain the correction variable, and recalculate the error according to the obtained correction variable until the obtained error is less than the allowable value.

According to some embodiments, the second solution of the present disclosure provides a solution system for dynamic simulation of a natural gas transmission pipeline network system, which adopts the following technical solution:

A solution system for dynamic simulation of a natural gas transmission pipeline network system, comprising:

The obtaining module is configured to obtain the topology structure of the natural gas transmission network, and construct the dynamic partial differential equation of the gas transmission pipeline;

A processing module configured to perform discretization and linearization processing on the built partial differential equations to obtain a linear equation system;

The solution module is configured to iteratively solve the obtained linear equations to obtain the air pressure and mass flow at each grid node of the gas transmission network under the same time layer, predict the node air pressure and pipeline flow of the gas transmission network, and complete Dynamic simulation of natural gas transmission pipeline network system.

According to some embodiments, the third solution of the present disclosure provides a computer-readable storage medium, adopting the following technical solution:

A computer-readable storage medium, on which a program is stored. When the program is executed by a processor, the steps in the method for solving the dynamic simulation of the natural gas transmission pipeline network system according to the first aspect of the present disclosure are implemented.

According to some embodiments, the fourth solution of the present disclosure provides an electronic device, which adopts the following technical solution:

An electronic device, including a memory, a processor, and a program stored on the memory and operable on the processor, when the processor executes the program, the natural gas transmission pipeline network system according to the first aspect of the present disclosure is realized Steps in the solution method for a dynamic simulation.

Compared with the prior art, the beneficial effects of the present disclosure are:

Based on the linearization and discretization grid method, the partial differential equation model describing the dynamic simulation of the gas transmission network is transformed into a linear equation model, which improves the speed of model solution and ensures the accuracy through iterative solution. Compared with the traditional method, the proposed method improves the stability of the simulation solution, reduces the number of variables to be solved, and can achieve a good fitting of the dynamic process.

Description of drawings

The accompanying drawings constituting a part of the present disclosure are used to provide a further understanding of the present disclosure, and the exemplary embodiments and descriptions of the present disclosure are used to explain the present disclosure, and do not constitute improper limitations to the present disclosure.

FIG. 1 is a flowchart of a solution method for dynamic simulation of a natural gas transmission pipeline network system in Embodiment 1 of the present disclosure;

FIG. 2 is a schematic diagram of a discretized simple network in Embodiment 1 of the present disclosure;

FIG. 3 is a flowchart of an iterative solution in Embodiment 1 of the present disclosure;

Fig. 4 is a structural block diagram of a solution system for dynamic simulation of a natural gas transmission pipeline network system in Embodiment 2 of the present disclosure.

Detailed ways

The present disclosure will be further described below in conjunction with the accompanying drawings and embodiments.

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

It should be noted that the terminology used herein is only for describing specific embodiments, and is not intended to limit the exemplary embodiments according to the present disclosure. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural, and it should also be understood that when the terms "comprising" and/or "comprising" are used in this specification, they mean There are features, steps, operations, means, components and/or combinations thereof.

In this disclosure, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom" etc. refer to The orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only a relative term determined for the convenience of describing the structural relationship between the components or elements of the present disclosure. Public restrictions.

In this disclosure, terms such as "fixed", "connected", and "connected" should be interpreted in a broad sense, which means that they can be fixedly connected, integrally connected or detachably connected; they can be connected directly or through an intermediate connection. The medium is indirectly connected. For relevant researchers or technical personnel in the field, the specific meanings of the above terms in the present disclosure can be determined according to specific situations, and should not be construed as limitations on the present disclosure.

In the case of no conflict, the embodiments in the present disclosure and the features in the embodiments can be combined with each other.

Embodiment one

Embodiment 1 of the present disclosure introduces a solution method for dynamic simulation of a natural gas transmission pipeline network system.

This embodiment provides a dynamic simulation solution method for a partial differential equation model of a gas transmission network based on discretized grids and linearization, and the solution variables are gas pressure p and gas mass flow rate q. This method divides the solution of the dynamic simulation model of the gas transmission network into three stages. First, the first stage identifies the topological structure of the gas transmission network and constructs a partial differential equation model of the gas transmission pipeline. In this stage, identify the number of connected pipes or connected loads at the end of each pipe, establish the corresponding relationship between connected pipes, and establish a simplified partial differential equation model of the gas pipeline described by pressure and mass flow rate; then, the second In the first stage, all the pipelines of the gas transmission network are divided into grids, and then the partial differential equation model is discretized and linearized, and the partial differential equations are transformed into linear equations, and based on the topological information of the first stage, the iterative solutions are set. Finally, in the third stage, for all the variables that need to be solved iteratively, based on the discretized linearized equation model, the corresponding error equation and correction equation are derived, and the linear equations are constructed and solved iteratively to obtain the gas transmission under the same time layer Air pressure and mass flow at each mesh node of the network. Repeat the final stage to gradually realize the dynamic simulation of the node pressure and pipeline mass flow of the gas transmission network within a specified period of time under the given initial steady-state conditions.

As shown in Figure 1, a solution method for dynamic simulation of a natural gas transmission pipeline network system includes:

Obtain the topological structure of the natural gas transmission network, and construct the dynamic partial differential equation of the gas transmission pipeline;

Discretize and linearize the constructed partial differential equations to obtain a system of linear equations;

Iteratively solve the obtained linear equations, obtain the air pressure and mass flow at each grid node of the gas transmission network under the same time layer, predict the node air pressure and pipeline flow of the gas transmission network, and complete the natural gas transmission pipeline network system Dynamic simulation.

As one or more implementations, the topological structure of the gas transmission network is identified, and a dynamic partial differential equation model of the gas transmission pipeline is constructed. Identify the connection relationship between each pipeline and count the load at the end of each pipeline. Based on the law of conservation of mass, Newton's second law of motion (law of conservation of momentum), the first law of thermodynamics (law of conservation of energy) and the real gas law, a gas pipeline partial differential equation model is established and simplified by general assumptions, which can be obtained by Gas pipeline partial differential equation model described by gas pressure p(t,x) and mass flow q(t,x):

Among them, t represents time, x represents the distance along the axis of the pipe, p represents the air pressure, D represents the inner diameter of the pipe, A represents the cross-sectional area of the pipe, λ represents the friction coefficient of the pipe, Z represents the gas compression coefficient, R represents the gas constant, T Represents temperature, q represents mass flow. In this embodiment, it is assumed that the direction of the gas flow in the pipeline is constant, so the mass flow is represented by a scalar.

As one or more implementations, an appropriate space step and time step are selected to divide all pipelines in the gas transmission network into grids. Discretize and linearize the partial differential equation model; the schematic diagram of the divided grid is shown in Figure 2, n is the number of the node, (p _n , q _n ) represents the air pressure and mass flow stored at the grid node n, q _i and q _j represent the head-end flow of each branch pipeline.

In the steady state, the gas pressure in the pipeline does not change with time, but is only a function of the spatial position. The gas flow does not change with time and space and is constant. Therefore, the first equation of formula (1) and the time derivative term in the second equation can be ignored, and the space partial derivative can be discretized to obtain the pipeline pressure calculation formula under steady-state conditions:

和/>

代表稳态时网格节点n和n-1处的气体压力，/>

表示稳态时第i根管道的质量流量。为简化表达式，定义两个常系数a＝ZRT和/>

In the formula,

and />

represents the gas pressure at grid nodes n and n-1 at steady state, />

Indicates the mass flow rate of the i-th pipe at steady state. To simplify the expression, define two constant coefficients a=ZRT and />

Based on the different node types, that is, the different positions of the nodes in the pipeline, different discrete formats are used as follows:

For mesh nodes in the middle of the pipeline, the discretization format is as follows:

For the pipeline start node and pipeline end node, the following discrete formats are used:

To simplify the expression, define constants:

In the formula, Δx represents the discrete space step, and Δt represents the discrete time step. It should be noted that, in order to simplify the expression, the superscript t of the variable to be calculated at this moment is ignored, and the superscript t-1 indicates the value of the corresponding variable at the previous moment, which is a constant during the solution process at this moment.

As one or more implementation manners, variables that need to be solved iteratively are set, and an iterative variable matrix is established. Except for the air pressure of the gas source node and the known flow rate of the load node, the air pressure and flow rate of other grid nodes are the required quantities, but it should be noted that in this embodiment, all the required quantities do not need to be iteratively solved.

According to formulas (3) and (4), for a pipeline, given the known quantity at the previous time and the air pressure distribution at this time, the flow distribution at this time can be directly calculated, so it is only necessary to use the air pressure as an iterative Solution variables; for the network, taking Figure 2 as an example, the flow from the end of the pipeline to each branch pipeline is also unknown. Therefore, in addition to the air pressure, the flow at the head end of each branch pipeline needs to be used as an iterative solution variable. That is, for the discrete gas pipeline network, except for the known gas source node pressure, the pressure of other discrete grid nodes is used as the iterative solution variable to establish the pressure variable matrix; according to the topology identification, except for the pipeline connected to the gas source, The head-end flow of other pipelines is used as the iterative solution variable to establish the flow variable matrix.

Using the steady-state pressure formula and the given steady-state gas mass flow rate, the steady-state node pressure of each grid node is calculated as the initial state of the network dynamic simulation.

As one or more implementations, for simplified representation, the following constant coefficients are defined:

Taking the middle node of the pipeline as an example, the equations of the middle node and its two adjacent nodes all adopt the discrete format shown in (3), that is:

If the pressure distribution is assumed to be p ^* and substituted into (7), an error occurs due to the inaccuracy of p ^* :

Here the grid point pressure and flow correction values need to be defined:

为该变量的假设值。在之后的迭代求解步骤中，会将对应变量上一时刻的值作为本时刻的假设初始值。In the formula, q _i represents the mass flow rate at the head end of the pipeline that needs to be solved iteratively for the i-th pipeline at this moment,

is the hypothetical value of this variable. In the subsequent iterative solution step, the value of the corresponding variable at the previous moment will be used as the assumed initial value at this moment.

Based on formula (7) and formula (8):

C2*p' _n -dp' _n+2 -dp' _n-2 = -E _n (10)

Formula (8) and formula (10) are the node pressure error equation and the node pressure correction equation respectively. In the same way, the pressure error equation and pressure correction equation of other nodes can be established. The error and correction equations of several special nodes are directly given below. Their structures are different from those of intermediate nodes, but they are essentially derived from the discrete format of (3) and (4), so no specific explanation will be given.

Pipe end node:

表示管道末端节点连接的k根分支管道首端流量假设值之和，也即该末端节点的质量流量的假设值，注意当管道末端连接负荷时，该项对应的变量转化为常量。In the formula,

Indicates the sum of the hypothetical values of the head-end flow of the k-branch pipeline connected to the end node of the pipeline, that is, the assumed value of the mass flow rate of the end node. Note that when the end of the pipeline is connected to a load, the corresponding variable of this item is converted into a constant.

The previous node of the end node of the pipeline:

The equation of this node is listed to illustrate that although the structure of its error equation and correction equation is consistent with that of the terminal node, the corresponding coefficients will change due to the different discrete formats used in the derivation of the equations in the present invention.

Pipeline head-end nodes (except gas source nodes):

C4*p′ _n -dp′ _n+2 +q′ _i ＝-E _n (16)

Since the flow variables of the set iterative solution are all the flow at the head end of the corresponding pipeline, and the variables are related to the end node of the preceding pipeline of the corresponding pipeline and the head node of the corresponding pipeline, the discrete format of formula (4) is adopted, and the error equation and correction The equation is:

q′ _i -2dp′ _i,1 +2dp′ _i,2 =-E _i (18)

和/>

分别代表第i根管道的前接管道的末端节点气压和第i根管道的首端节点气压。In the formula,

and />

Represent the air pressure at the end node of the preceding pipeline of the i-th pipeline and the air pressure at the head-end node of the i-th pipeline, respectively.

The flow chart of iterative solution shown in Figure 3, in the process of iterative solution, the node air pressure and mass flow at the previous moment are used as the hypothetical values p ^* and q ^* of the variables to be obtained at this moment, that is, the initial value of iteration; Calculate the error through the node pressure error equation and flow error equation, and judge the size relationship between the calculated error and the allowable value. If the obtained error is less than the allowable value, calculate the flow of the remaining nodes based on the air pressure and flow after iterative solution. , to complete the dynamic simulation solution of the natural gas transmission pipeline network system; if the obtained error is not less than the allowable value, construct a linear correction equation group, solve it by matrix operation, and obtain the correction variable, and recalculate the error according to the obtained correction variable until Until the obtained error is less than the allowable value; that is, to realize the dynamic simulation of the gas pipeline network within a given period of time.

In this embodiment, based on the linearization and discretization grid method, the partial differential equation model describing the dynamic simulation of the gas transmission network is transformed into a linear equation model, so as to improve the speed of model solution and ensure the accuracy through iterative solution. Compared with the traditional method, the proposed method improves the stability of the simulation solution, reduces the number of variables to be solved, and can achieve a good fitting of the dynamic process.

Embodiment two

Embodiment 2 of the present disclosure introduces a solution system for dynamic simulation of a natural gas transmission pipeline network system.

As shown in Figure 4, a solution system for dynamic simulation of a natural gas transmission pipeline network system includes:

The obtaining module is configured to obtain the topology structure of the natural gas transmission network, and construct the dynamic partial differential equation of the gas transmission pipeline;

A processing module configured to perform discretization and linearization processing on the built partial differential equations to obtain a linear equation system;

The solution module is configured to iteratively solve the obtained linear equations to obtain the air pressure and mass flow at each grid node of the gas transmission network under the same time layer, predict the node air pressure and pipeline flow of the gas transmission network, and complete Dynamic simulation of natural gas transmission pipeline network system.

The detailed steps are the same as the solution method of the dynamic simulation of the natural gas transmission pipeline network system provided in Embodiment 1, and will not be repeated here.

Embodiment three

Embodiment 3 of the present disclosure provides a computer-readable storage medium.

A computer-readable storage medium, on which a program is stored. When the program is executed by a processor, the steps in the method for solving the dynamic simulation of the natural gas transmission pipeline network system according to Embodiment 1 of the present disclosure are implemented.

The detailed steps are the same as the solution method of the dynamic simulation of the natural gas transmission pipeline network system provided in Embodiment 1, and will not be repeated here.

Embodiment Four

Embodiment 4 of the present disclosure provides an electronic device.

An electronic device, including a memory, a processor, and a program stored in the memory and operable on the processor, when the processor executes the program, the natural gas transmission pipeline network system according to Embodiment 1 of the present disclosure is realized Steps in the solution method for a dynamic simulation.

The detailed steps are the same as the solution method of the dynamic simulation of the natural gas transmission pipeline network system provided in Embodiment 1, and will not be repeated here.

The above descriptions are only preferred embodiments of the present disclosure, and are not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included within the protection scope of the present disclosure.

Although the specific implementation of the present disclosure has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the present disclosure. Those skilled in the art should understand that on the basis of the technical solutions of the present disclosure, those skilled in the art do not need to pay creative work Various modifications or variations that can be made are still within the protection scope of the present disclosure.

Claims (8)

1. A solution method for dynamic simulation of a natural gas pipeline network system, characterized in that it comprises: Obtain the topological structure of the natural gas transmission network, and construct the dynamic partial differential equation of the gas transmission pipeline; Discretize and linearize the constructed partial differential equations to obtain a system of linear equations; Iteratively solve the obtained linear equations, obtain the air pressure and mass flow at each grid node of the gas transmission network under the same time layer, predict the node air pressure and pipeline flow of the gas transmission network, and complete the natural gas transmission pipeline network system Dynamic simulation; Select the space step and time step, divide all the pipelines of the gas transmission network into grids, and discretize and linearize the partial differential equations; in dynamic, based on the difference in node type, that is, the difference in the location of the pipeline where the node is located, in different discrete formats; In the iterative solution process, the node air pressure and mass flow at the previous moment are used as the assumed values p ^* and q ^* of the variables to be obtained at this moment, that is, the initial value of the iteration; calculated by the node air pressure error equation and flow error equation Error, judge the size relationship between the calculated error and the allowable value, if the obtained error is less than the allowable value, calculate the flow of the remaining nodes based on the air pressure and flow after iterative solution, and complete the dynamic of the natural gas transmission pipeline network system Simulation solution; if the obtained error is not less than the allowable value, construct a linear correction equation group, solve it by matrix operation, obtain the correction variable, and recalculate the error according to the obtained correction variable until the obtained error is less than the allowable value; In the steady state, the gas pressure in the pipeline does not change with time, the gas flow does not change with time and space, and the space partial derivative is discrete, and the calculation formula of the pipeline pressure under steady state conditions is obtained:

in,

and />

represents the gas pressure at grid nodes n and n-1 at steady state, />

Indicates the mass flow rate of the i-th pipe at steady state; When dynamic, For mesh nodes in the middle of the pipeline, the discretization format is as follows:

For the pipeline start node and pipeline end node, the following discrete formats are used:

To simplify the expression, define constants:

Among them, Δx represents a discrete space step, and Δt represents a discrete time step. 2. the solution method of a kind of natural gas pipeline network system dynamic simulation as described in claim 1, it is characterized in that, identify the connection relationship between each pipeline of natural gas, count the load situation of each pipeline end; Set up gas pipeline Partial differential equation model, and using general assumptions to simplify, can get the gas pipeline partial differential equation model described by gas pressure p(t,x) and mass flow q(t,x):

Among them, t represents time, x represents the distance along the axis of the pipeline, represents air pressure, D represents the inner diameter of the pipeline, A represents the cross-sectional area of the pipeline, λ represents the friction coefficient of the pipeline, Z represents the gas compression coefficient, R represents the gas constant, T represents temperature, q stands for mass flow. 3. the solution method of a kind of natural gas pipeline network system dynamic simulation as described in claim 1, it is characterized in that: In the steady state, the gas pressure in the pipeline does not change with time, the gas flow does not change with time and space, and the space partial derivative is discrete, and the calculation formula of the pipeline pressure under steady state conditions is obtained:

in,

and />

represents the gas pressure at grid nodes n and n-1 at steady state, />

Indicates the mass flow rate of the i-th pipe at steady state; When dynamic, For mesh nodes in the middle of the pipeline, the discretization format is as follows:

For the pipeline start node and pipeline end node, the following discrete formats are used:

To simplify the expression, define constants:

Among them, Δx represents a discrete space step, and Δt represents a discrete time step. 4. the solution method of a kind of natural gas pipeline network system dynamic simulation as described in claim 3, it is characterized in that, the variable that needs iterative solution is set, iterative variable matrix is set up; For a pipeline, given last moment Given the known quantity and the air pressure distribution at this moment, the flow distribution at this moment is directly calculated, and the air pressure and the flow at the head end of each branch pipeline are used as variables for iterative solution to establish a pressure variable matrix and a flow variable matrix. 5. the solution method of a kind of natural gas pipeline network system dynamic simulation as described in claim 4, it is characterized in that, based on steady state pressure formula and given steady state gas mass flow rate, calculate the steady state of each grid node As the initial state of network dynamic simulation, the node pressure error equation, node pressure correction equation, flow error equation and flow correction equation are obtained by defining the grid point pressure and flow correction values, and the discretization and calculation of partial differential equations are completed. After linearization, a system of linear equations is obtained. 6. A solution system for dynamic simulation of a natural gas transmission pipeline network system, characterized in that it includes: The obtaining module is configured to obtain the topology structure of the natural gas transmission network, and construct the dynamic partial differential equation of the gas transmission pipeline; A processing module configured to perform discretization and linearization processing on the built partial differential equations to obtain a linear equation system; The solution module is configured to iteratively solve the obtained linear equations to obtain the air pressure and mass flow at each grid node of the gas transmission network under the same time layer, predict the node air pressure and pipeline flow of the gas transmission network, and complete Dynamic simulation of natural gas transmission pipeline network system; Select the space step and time step, divide all the pipelines of the gas transmission network into grids, and discretize and linearize the partial differential equations; in dynamic, based on the difference in node type, that is, the difference in the location of the pipeline where the node is located, in different discrete formats; In the iterative solution process, the node air pressure and mass flow at the previous moment are used as the assumed values p ^* and q ^* of the variables to be obtained at this moment, that is, the initial value of the iteration; calculated by the node air pressure error equation and flow error equation Error, judge the size relationship between the calculated error and the allowable value, if the obtained error is less than the allowable value, calculate the flow of the remaining nodes based on the air pressure and flow after iterative solution, and complete the dynamic of the natural gas transmission pipeline network system Simulation solution; if the obtained error is not less than the allowable value, construct a linear correction equation group, solve it by matrix operation, obtain the correction variable, and recalculate the error according to the obtained correction variable until the obtained error is less than the allowable value; In the steady state, the gas pressure in the pipeline does not change with time, the gas flow does not change with time and space, and the space partial derivative is discrete, and the calculation formula of the pipeline pressure under steady state conditions is obtained:

in,

and />

represents the gas pressure at grid nodes n and n-1 at steady state, />

Indicates the mass flow rate of the i-th pipe at steady state; When dynamic, For mesh nodes in the middle of the pipeline, the discretization format is as follows:

For the pipeline start node and pipeline end node, the following discrete formats are used:

To simplify the expression, define constants:

Among them, Δx represents the discrete space step, and Δt represents the discrete time step. 7. A computer-readable storage medium on which a program is stored, characterized in that, when the program is executed by a processor, it realizes the dynamic simulation of the natural gas transmission pipeline network system according to any one of claims 1-5 Steps in the solve method. 8. An electronic device, comprising a memory, a processor, and a program stored on the memory and operable on the processor, characterized in that, when the processor executes the program, it realizes any one of claims 1-5. The steps in the solution method for the dynamic simulation of the natural gas transmission pipeline network system described in the item.

Images