Quasi-steady-state simulation method and device for electro-mechanical coupled system based on branch compensation method and computer readable medium

Abstract

An electric-gas coupling system quasi-steady-state simulation method, device and computer readable medium based on branch compensation method. It relates to the improvement of the simulation method of the electric-gas coupling system. It is suitable for occasions with high real-time requirements and can realize fast approximate quasi-dynamic energy flow calculation. It includes the following steps: 1) in the natural gas system, the "circuit-like" method is used to model the natural gas pipeline in a steady state; 2) using the matrix inverse auxiliary theorem, the node pressure is calculated without considering the change of the gas resistance of each pipeline; 3) calculating the branch flow without considering the change of the gas resistance of each pipeline; 4) calculating the node gas pressure considering the change of the gas resistance of each pipeline. The present application extends the branch compensation method to the natural gas system and is suitable for comprehensive modeling, quasi-steady-state simulation and many other scenes of the electric-gas coupling system. When the branch connection condition changes locally, the node admittance matrix is not recalculated, but an approximate result in the new scene is given based on the original calculation result by using the correction method.

Description

Technical Field

[0001] This invention relates to the field of integrated energy technology, and in particular to an improved simulation method applicable to electro-pneumatic coupling systems. Background Technology

[0002] The global energy structure is undergoing a low-carbon transition driven by increased natural gas consumption, leading to rapid growth in global natural gas demand. This is both an inherent requirement and an external manifestation of the low-carbon transition. Natural gas pipelines are a primary means of distribution for modern life and industrial production. The design and operation of natural gas transmission and distribution networks require reliable hydraulic flow calculations to obtain necessary parameters. Furthermore, considering user gas consumption, reliable hydraulic calculations can determine the pressure at each node of the pipeline under maximum pressure requirements for one or more pipelines, ensuring normal operation of the network. Simultaneously, hydraulic calculations are also used to adjust the outlet pressure of various pressure regulating valves to meet the required transmission pressure under emergency conditions.

[0003] A power system mainly includes power sources, transformers, transmission lines, and loads. The composition of a natural gas system is similar to that of a power system, including gas sources, compressors, gas pipelines, and loads. In the traditional fields of power and natural gas systems, their respective modeling and analysis methods are relatively mature: power systems are mainly represented by power flow models, with key variables including voltage magnitude and phase angle at each node, injected power at each node, and active / reactive power flow along lines. The main variables in a natural gas system are pressure, flow rate, and density, and the hydraulic equations used in steady-state calculations are derived. There are many methods for approximating power flow calculations in power systems, such as the DC method, distribution coefficient method, fast decoupling primary power flow method, and compensation method suitable for branch interruption simulation, as well as the DC method and power generation transfer distribution coefficient method suitable for generator interruption simulation.

[0004] Existing technology "public number: CN114398752A The patent document, titled "An Analysis Method and System Based on an Interval Energy Flow AC Model of an Electro-Gas Coupled System," aims to establish and solve an energy flow AC model, thereby analyzing the gas flow variation range of natural gas branches and the state parameter range of power system nodes. It provides an analysis method and system based on an interval energy flow AC model of an electro-gas coupled system, whose basic technical solution includes the following three steps:

[0005] S1: Establish an interval energy flow AC model, which includes an AC power flow model for the power system and a steady-state hydraulic nonlinear model for the natural gas system;

[0006] S2: Based on the interval energy flow AC model established in S1, establish a solution model for the state variables of the natural gas system branches and the power system nodes;

[0007] S3: Analyze the solution models for the natural gas system branches and the power system nodes established in S2, and combine them with the constraints to obtain the range of flow parameters for the natural gas system branches and the range of node state parameters for the power system in the interval energy flow AC model.

[0008] However, the aforementioned existing technologies do not focus on approximate simulation of electro-pneumatic coupling systems, making them unsuitable for applications with high real-time requirements. Summary of the Invention

[0009] To address the above-mentioned technical problems, this invention provides a quasi-steady-state simulation method, apparatus, and computer-readable medium for electro-pneumatic coupling systems based on the branch compensation method, which is suitable for applications with high real-time requirements and enables fast approximate quasi-dynamic energy flow calculation.

[0010] The technical solution of the present invention includes the following steps:

[0011] 1) Steady-state modeling of natural gas pipelines is performed using circuit-like methods;

[0012] 2) Using the matrix inversion auxiliary theorem, calculate the nodal pressure and branch flow rate when the network topology changes without considering changes in air resistance in each pipe:

[0013] 3) Based on the nodal pressure and branch flow rate without considering changes in air resistance, calculate the nodal pressure considering changes in air resistance in each pipeline:

[0014] Resolve the air resistance in the pipeline, and correct the nodal air pressure based on the air resistance and flow rate. Repeat step 3) 1-2 times to obtain the result as an approximate hydraulic calculation.

[0015] Step 1) specifically refers to:

[0016] Distributed parameter modeling was performed on the natural gas pipeline, namely...

[0017] ;

[0018] in, The pressure at a certain point in the pipeline, Let the mass flow rate be at a certain point in the pipeline. For spatial coordinates, Using time as the coordinate, , , These represent the air resistance, air sensation, and air capacity per unit length at a point in the pipeline, respectively.

[0019] Choose the steady-state case, that is, let all pairs The partial derivative is zero, and substituting it into... The expression is obtained as follows:

[0020] ;

[0021] in, The coefficient of friction, The speed of sound at the gas supply temperature. The cross-sectional area of ​​the pipe. The diameter of the pipe;

[0022] Assuming the same pipe , , , , All remain unchanged, thus yielding the expression for the air resistance of the pipeline.

[0023] ;

[0024] in R is the pipe length, and R is the pipe air resistance.

[0025] In the initial iteration, and Select the value when the pipeline is working normally.

[0026] Step 2) specifically refers to:

[0027] The nodal method equations for the gas network are as follows:

[0028] ;

[0029] in, It is the node admittance matrix of the natural gas network, which can be calculated based on the gas resistance parameters of each pipeline. It is node pressure. This refers to the node-injected traffic; when the network structure or parameters change but the node-injected traffic remains constant, a new network equation emerges:

[0030] ;

[0031] in, To simulate the change in the admittance matrix when a branch is disconnected or its parameters change, This represents the changed nodal pressure; it can be described using a nodal-branch incidence matrix as follows:

[0032] ;

[0033] in, Composed of branch admittance parameters that change 3D diagonal matrix For the corresponding changing element 1D node-branch incidence matrix; let Using the matrix inversion auxiliary theorem:

[0034] ;

[0035] We can obtain:

[0036] ;

[0037] in:

[0038] ;

[0039] when When it is irreversible, equation (6) can also be written in the following form:

[0040] ;

[0041] In approximate analysis, the original operating point is generally known. Therefore, if changes in air resistance are not considered and the original state variable values ​​are available, the calculation cost using post-compensation is minimized, i.e.:

[0042] ;

[0043] in, This is the corrected air pressure.

[0044] Step 3) specifically refers to:

[0045] Branch flow The calculation is as follows:

[0046] ;

[0047] in,

[0048] ;

[0049] in, This is the branch air resistance matrix before the network change. This is the branch air resistance matrix after network changes. For the node affinity matrix, For only the position of the element that changes has a non-zero element 1. Dimensional column vector.

[0050] Step 4) specifically involves:

[0051] ;

[0052] in, , These represent the branch flows before and after the network structure change. , These represent the average pipeline pressure before and after the network structure change, respectively. Matrix division in the formula refers to element-wise division, and `diag()` generates a diagonal matrix. .

[0053] The apparatus for implementing the quasi-steady-state simulation method for electro-electric coupled systems based on the branch compensation method of the present invention includes:

[0054] The Natural Gas Pipeline Steady-State Modeling Module is used to perform steady-state modeling of natural gas pipelines using circuit-like methods.

[0055] Module 1 is used to calculate the node pressure and branch flow rate when the network topology changes without considering the changes in air resistance of each pipe, using the matrix inversion auxiliary theorem.

[0056] Calculation module two is used to re-solve the air resistance of the pipeline and correct the nodal air pressure based on the air resistance and flow rate of the pipeline. Step 3) is repeated 1 to 2 times to obtain the result as an approximate hydraulic calculation.

[0057] A computer-readable storage medium having a computer program stored thereon, which, when executed, implements the quasi-steady-state simulation method for electro-pneumatic coupling systems based on the branch compensation method of the present invention.

[0058] This invention is based on a "circuit-like" model of a natural gas system and references the approximate power flow calculation method for power systems, extending the branch compensation method therein to natural gas systems. It is applicable to various scenarios such as comprehensive modeling and quasi-steady-state simulation of electro-gas coupled systems. When local changes occur in branch connections, instead of recalculating the node admittance matrix, a correction method is used to provide approximate results for the new scenario based on the original calculation results.

[0059] This invention is applied to integrated energy networks (natural gas / electricity) to perform rapid and approximate quasi-dynamic energy flow calculations on the real-time changes of any branch in a natural gas pipeline. Compared to other existing algorithms, the calculation speed is significantly improved with smaller errors, providing important reference for the optimization and improvement of electro-gas coupling systems. Attached Figure Description

[0060] Figure 1 This is a flowchart of the present invention.

[0061] Figure 2 This is a schematic diagram of the integrated energy network of this invention. Detailed Implementation

[0062] The quasi-steady-state simulation method for electro-electric coupled systems based on branch compensation of the present invention operates in the following conditions: Figure 2 In such a scenario, as Figure 1 The steps are as follows:

[0063] 1) For natural gas systems, the "circuit-like" method is used to perform steady-state modeling of natural gas pipelines;

[0064] Some studies have modeled distributed parameters for natural gas pipelines by analogy to the transmission line equations of power systems.

[0065] ;

[0066] in, The pressure at a certain point in the pipeline, Let the mass flow rate be at a certain point in the pipeline. For spatial coordinates, Using time as the coordinate, , , These are "air resistance", "air sensation", and "air capacity" per unit length at a point in the pipeline, respectively.

[0067] Choose the steady-state case, that is, let all pairs The partial derivative is zero, and substituting it into... The expression is obtained as follows:

[0068] ;

[0069] in, The coefficient of friction, The speed of sound at the gas supply temperature. The cross-sectional area of ​​the pipe. The diameter of the pipe;

[0070] Assuming the same pipe , , , , All remain unchanged, thus yielding the expression for the air resistance of the pipeline.

[0071] ;

[0072] in R is the pipe length, and R is the pipe air resistance.

[0073] In the initial iteration, and Select the value when the pipeline is working normally.

[0074] 2) Using the matrix inversion auxiliary theorem, calculate the nodal pressures when the network topology changes without considering changes in air resistance in each pipe:

[0075] Referring to the nodal method approach in circuit analysis, the nodal method equations for the gas network can be listed as follows:

[0076] ;

[0077] in, It is the node admittance matrix of the natural gas network, which can be calculated based on the gas resistance parameters of each pipeline. It is the node pressure (column vector). This refers to the node-injected traffic (column vector); when the network structure or parameters change but the node-injected traffic remains the same, a new network equation emerges:

[0078] ;

[0079] in, To simulate the change in the admittance matrix when a branch is disconnected or its parameters change, This represents the changed nodal pressure; it can be described using a nodal-branch incidence matrix as follows:

[0080] ;

[0081] in, Composed of branch admittance parameters that change 3D diagonal matrix For the corresponding changing element 1D node-branch incidence matrix; let Using the matrix inversion auxiliary theorem:

[0082] ;

[0083] We can obtain:

[0084] ;

[0085] in:

[0086] ;

[0087] when When it is irreversible, equation (6) can also be written in the following form:

[0088] ;

[0089] In approximate analysis, the original operating point is generally known, so the original state variable values ​​are available. Therefore, the calculation cost is minimized by using the post-compensation method, i.e.:

[0090] ;

[0091] in, This is the corrected air pressure.

[0092] The original node admittance matrix is ​​calculated based on the model parameters obtained from the steady-state modeling process described in step 1. The original node admittance matrix and the branch correlation matrix when the network changes are then substituted into the matrix inversion auxiliary theorem to obtain the changed node pressure.

[0093] Calculate the branch flow rate without considering changes in air resistance in each pipe:

[0094] Branch flow The calculation is as follows:

[0095] ;

[0096] in,

[0097] ;

[0098] in, This is the branch air resistance matrix before the network change. This is the branch air resistance matrix after the network change (without considering the air resistance changes of each pipe). For the node affinity matrix, For only the position of the element that changes has a non-zero element 1. Dimensional column vector.

[0099] 3) Based on the nodal pressure and branch flow rate without considering changes in air resistance, calculate the nodal pressure considering changes in air resistance in each pipeline:

[0100] Since changes in branch flow rate will cause changes in pipe air resistance, the pipe air resistance needs to be recalculated, and the nodal air pressure can be corrected based on the pipe air resistance and pipe flow rate. This process can be repeated 1 to 2 times, and the results can be used as approximate hydraulic calculation results.

[0101] ;

[0102] in, , These represent the branch flows before and after the network structure change. , These represent the average pipeline pressure before and after the network structure change, respectively. Matrix division in the formula refers to element-wise division, and `diag()` generates a diagonal matrix. .

[0103] The following combination Figure 2 This invention will be further explained below. To facilitate understanding of the operational carrier of this invention, [further details will be provided]. Figure 2 The reference numerals in the accompanying drawings are explained as follows:

[0104] The upper part of the diagram shows the natural gas system.

[0105] P1 represents the natural gas source; Arabic numerals 1, 2, 3...8 indicate natural gas pipeline network nodes; ①~⑦ represent natural gas pipelines; ⑧ represents the compressor (C).

[0106] m in Injecting gas flow, m G1 For the flow consumption of gas turbine unit G1, m G2 For the flow consumption of gas turbine unit G2;

[0107] m L1 For normal load flow consumption, one m L2 For normal load flow consumption, m L3 This is the normal load flow consumption.

[0108] The lower half of the diagram shows the power system, with G1~G4 being generator sets and I~IV being busbars P. d1 For electrical load 1, P d2 For electrical load 2, P d3 For electrical load three, P d4 The electrical load is four, and a, b, c, and d are power transmission lines.

[0109] Taking a fault in natural gas pipeline ② as an example, the effectiveness of the proposed steady-state hydraulic approximation calculation method for natural gas based on branch compensation is verified. First, considering that compressor C operates by controlling the outlet pressure, the natural gas network is divided into blocks from the compressor branch, and the network after the compressor branch is equivalent to the load of node 4. Based on the initial flow of the pipeline, the model parameters and variables of this part of the natural gas network can be obtained;

[0110] ;

[0111] Since the pressure at node 1 is known, this node is selected as the reference node. After matrix transformation, the model parameters of the part to be determined can be obtained:

[0112] ;

[0113] When pipe ② fails, we have:

[0114] ;

[0115] Then we have: ;

[0116] Updated later Perform one iteration as an approximate calculation result:

[0117] ;

[0118] Observation reveals that the pressure at node 4 is approximately 13.80 bar. The compressor has not reached its maximum compression ratio limit, allowing for pressure control; therefore, the pressure at the downstream node remains unchanged. The approximate calculation results are presented in Table 1 and compared with the results of direct steady-state hydraulic calculations.

[0119] Table 1 Comparison of Steady-State Hydraulic Approximation Calculation Results for Pipeline ② Fault

[0120]

[0121] The results comparison revealed that the calculated branch flow was error-free. This is because after the failure of pipe ②, the pipe network became a branched network. Since the flow injected into the nodes was determined, the calculated branch flow was accurate. However, due to the pipe... The value changes with the system's operating state, depending not only on the branch flow but also on the pressure at both ends of the branch. Therefore, the calculation results for the node pressure have a certain error, with a maximum relative error of 6.623%, which basically meets the requirements for preliminary screening accuracy. Regarding calculation speed, the average calculation time for the approximate calculation is 0.006s, while the average time for the accurate calculation is 0.045s, representing an improvement in calculation speed of approximately 7.5 times.

[0122] This invention is applicable to applications with high real-time requirements, enabling rapid approximate quasi-dynamic energy flow calculations. Technically: 1) In natural gas systems, a "circuit-like" method is used for steady-state modeling of natural gas pipelines; 2) The matrix inversion auxiliary theorem is used to calculate nodal pressures without considering changes in pipeline gas resistance; 3) Branch flow rates are calculated without considering changes in pipeline gas resistance; 4) Nodal gas pressures are calculated considering changes in pipeline gas resistance. This invention extends the branch compensation method to natural gas systems, applicable to various scenarios such as comprehensive modeling and quasi-steady-state simulation of electro-gas coupled systems. When local changes occur in branch connections, the nodal admittance matrix is ​​not recalculated; instead, a correction method is used to provide approximate results for the new scenario based on the original calculation results.

[0123] The present invention proposes an approximate calculation method for steady-state hydraulics in natural gas systems—the branch compensation method. Its advantages are: compared with other algorithms, this method has a significantly improved calculation speed and smaller error, and has important reference significance for the optimization and improvement of electro-gas coupled systems.

[0124] This invention is not limited to the above embodiments. Based on the technical solutions disclosed in this invention, those skilled in the art can make some substitutions and changes to some of the technical features without creative effort, and all such substitutions and changes are within the protection scope of this invention.

Claims

1. A quasi-steady-state simulation method for electro-electric coupled systems based on branch compensation, characterized in that, Includes the following steps: 1) Steady-state modeling of natural gas pipelines is performed using circuit-like methods; 2) Using the matrix inversion auxiliary theorem, calculate the nodal pressure and branch flow rate when the network topology changes without considering changes in air resistance in each pipe: 3) Based on the nodal pressure and branch flow rate without considering changes in air resistance, calculate the nodal pressure considering changes in air resistance in each pipeline: Resolve the air resistance in the pipeline, and correct the nodal air pressure based on the air resistance and flow rate. Repeat step 3) 1-2 times to obtain the result as an approximate hydraulic calculation. Step 2) specifically refers to: The nodal method equations for the gas network are as follows: （2.1） in, It is the node admittance matrix of the natural gas network, which can be calculated based on the gas resistance parameters of each pipeline. It is node pressure. This refers to the node-injected traffic; when the network structure or parameters change but the node-injected traffic remains constant, a new network equation emerges: （2.2） in, To simulate the change in the admittance matrix when a branch is disconnected or its parameters change, This represents the changed nodal pressure; it can be described using a nodal-branch incidence matrix as follows: （2.3） in, Composed of branch admittance parameters that change 3D diagonal matrix For the corresponding changing element 1D node-branch incidence matrix; let Using the matrix inversion auxiliary theorem: （2.4） We can obtain: （2.5） in: （2.6） when When it is irreversible, equation (6) can also be written in the following form: （2.7） In approximate analysis, the original operating point is known. Therefore, if changes in air resistance are not considered, the original state variable values ​​are available. Thus, the post-compensation method minimizes the computational cost, i.e.: ， in, This is the corrected air pressure; Step 3) specifically refers to: Branch flow The calculation is as follows: （3.1） in, （3.2） in, This is the branch air resistance matrix before the network change. This is the branch air resistance matrix after network changes. For the node affinity matrix, For only the position of the element that changes has a non-zero element 1. Dimensional column vector; in, （4.1） （4.2） in, , These represent the branch flows before and after the network structure change. , These represent the average pipeline pressure before and after the network structure change, respectively. Matrix division in the formula refers to element-wise division, and `diag()` generates a diagonal matrix. .

2. The quasi-steady-state simulation method for an electro-electric coupled system based on branch compensation method according to claim 1, characterized in that, Step 1) specifically refers to: Distributed parameter modeling was performed on the natural gas pipeline, namely... （1.1） in, The pressure at a certain point in the pipeline, Let the mass flow rate be at a certain point in the pipeline. For spatial coordinates, Using time as the coordinate, , , These represent the air resistance, air sensation, and air capacity per unit length at a point in the pipeline, respectively. Choose the steady-state case, that is, let all pairs The partial derivative is zero, and substituting it into... The expression is obtained as follows: （1.2） in, The coefficient of friction, The speed of sound at the gas supply temperature. The cross-sectional area of ​​the pipe. The diameter of the pipe; Assuming the same pipe , , , , All remain unchanged, thus yielding the expression for the air resistance of the pipeline. （1.3） in R is the pipe length, and R is the pipe air resistance.

3. The quasi-steady-state simulation method for an electro-electric coupling system based on branch compensation method according to claim 2, characterized in that, In the initial iteration, and Select the value when the pipeline is working normally.

4. An apparatus for implementing the quasi-steady-state simulation method for an electro-electric coupled system based on the branch compensation method as described in claim 1, characterized in that, include: The Natural Gas Pipeline Steady-State Modeling Module is used to perform steady-state modeling of natural gas pipelines using circuit-like methods. Module 1 is used to calculate the node pressure and branch flow rate when the network topology changes without considering the changes in air resistance of each pipe, using the matrix inversion auxiliary theorem. Calculation module two is used to re-solve the air resistance of the pipeline and correct the nodal air pressure based on the air resistance and flow rate of the pipeline. Step 3) is repeated 1 to 2 times to obtain the result as an approximate hydraulic calculation.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed, it implements the quasi-steady-state simulation method for electro-electric coupling systems based on the branch compensation method as described in any of claims 1-3.

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