Safety evaluation method and system for comprehensive energy system planning based on energy path theory

Abstract

This invention relates to the field of integrated energy technology and provides a safety assessment method and system for integrated energy system planning based on energy path theory. It constructs a continuous power flow model that integrates a steady-state AC power flow model of the power system and a dynamic gas flow model of the natural gas system. This overcomes the limitations of traditional static models in characterizing the dynamic differences of multi-energy systems, more realistically reflecting the system response characteristics under faults. It utilizes a linear sensitivity method based on the singularity of saddle-node bifurcation points to achieve rapid initial fault screening. Combined with generalized curve fitting, it accurately estimates load margin and completes secondary screening. Finally, through dynamic continuous energy flow analysis, it precisely assesses the final fault set. This approach not only solves the problems of overly optimistic and insufficient dynamic response characterization in existing systems, but also considers the impact of power-gas faults collaboratively within a unified framework, gradually identifying key vulnerable lines and load margin indicators, significantly improving the accuracy and reliability of integrated energy system safety assessment.

Description

Technical Field

[0001] This invention relates to the field of integrated energy technology, and in particular to a safety assessment method and system for integrated energy system planning based on energy path theory. Background Technology

[0002] With the deep coupling and synergistic utilization of multiple energy forms such as electricity, natural gas, and heat, integrated energy systems have gradually become an important development direction for modern energy systems due to their ability to improve energy utilization efficiency and promote multi-energy complementarity. However, multi-energy networks exhibit significant differences in structure, operating mechanisms, and dynamic characteristics. Their internal coupling relationships are complex, energy conversion chains are long, and fault propagation paths are diverse, making their safe operation more challenging than that of single-energy systems. Large-scale power outages caused by electrical-gas coupling failures, such as gas supply interruptions, gas turbine shutdowns, increased fluctuations in renewable energy, and insufficient reserve capacity, can all lead to power system supply-demand imbalances and even cascading failures. Therefore, conducting safety assessments of integrated energy systems, identifying weaknesses and potential risks, and thereby improving the system's risk perception, early warning, and prevention capabilities have become crucial issues that urgently need to be addressed in the field of safe operation of integrated energy systems.

[0003] Existing safety assessment methods primarily originate from the power system field, typically including static safety assessment methods based on steady-state energy flow calculations and dynamic safety assessment methods combining real-time measurements and rapid simulations. As the coupling between power systems and natural gas systems deepens, some research has attempted to extend traditional power system safety assessment methods to integrated energy systems, analyzing issues such as fault propagation, static safety zones, vulnerability indicators, and safe operating boundaries. However, most existing technologies are still based on steady-state models, failing to fully consider the fundamental differences between natural gas systems and power systems in terms of flow velocity, transport delays, pipeline gas storage effects, and dynamic changes in node pressure. This makes it difficult to accurately reflect the dynamic response characteristics and true safety boundaries of integrated energy systems under fault conditions. Especially when conducting real-time operational safety assessments, using static energy flow models can easily lead to overly optimistic safety conclusions, thus affecting the accuracy and reliability of the assessment results. Furthermore, while some existing studies consider the dynamic characteristics of natural gas systems, they fail to simultaneously consider the synergistic effects of faults in power and natural gas networks within the same framework, thus still falling short of the practical needs for identifying weaknesses and assessing the safety of integrated energy systems. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a safety assessment method and system based on energy path theory for integrated energy system planning, which can improve the accuracy of safety assessment.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A security assessment method for integrated energy system planning based on energy path theory includes:

[0007] A continuous power flow model for a comprehensive energy system is constructed based on energy path theory. The continuous power flow model includes a steady-state AC power flow model for the power system and a dynamic gas flow model for the natural gas system.

[0008] Based on the continuous power flow model, the linear sensitivity analysis method is used to preliminarily screen the preset N-1 fault set by utilizing the singularity of the integrated energy system at the saddle-node bifurcation point to obtain the preliminary fault set.

[0009] The load margin of the preliminary fault set is estimated using the generalized curve fitting method, and the load margin estimation result is obtained.

[0010] The preliminary fault set is further filtered based on the load margin estimation results to obtain the final fault set.

[0011] The final fault set is evaluated using a dynamic continuous energy flow analysis method to obtain the critical vulnerable lines of the integrated energy system and their corresponding load margin indices.

[0012] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is as follows:

[0013] A safety assessment system for integrated energy system planning based on energy path theory includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the various steps of the aforementioned safety assessment method for integrated energy system planning based on energy path theory.

[0014] The beneficial effects of this invention are as follows: It constructs a continuous power flow model that integrates the steady-state AC power flow model of the power system and the dynamic gas flow model of the natural gas system, breaking through the limitation of traditional static models that cannot characterize the dynamic differences of multi-energy systems. It more realistically reflects the system response characteristics under faults. It uses the linear sensitivity method of saddle-node bifurcation singularity to achieve rapid preliminary screening of faults. Combined with generalized curve fitting, it accurately estimates the load margin and completes secondary screening. Then, it accurately evaluates the final fault set through dynamic continuous energy flow analysis. It not only solves the problems of existing optimistic and insufficient dynamic response characterization, but also considers the impact of electrical and gas faults in a unified framework, gradually identifying key vulnerable lines and load margin indicators, and significantly improving the accuracy and reliability of integrated energy system security assessment. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating a safety assessment method for integrated energy system planning based on energy path theory, according to an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of a safety assessment system for integrated energy system planning based on energy path theory, according to an embodiment of the present invention. Detailed Implementation

[0017] Definitions:

[0018]

[0019] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0020] In existing technologies, the deep coupling and synergy of multiple energy sources such as electricity, natural gas, and heat has made integrated energy systems a core development direction of modern energy systems. These systems are mainly applied in multi-energy linkage scenarios such as industrial parks, urban areas, and large energy hubs, covering complex operating conditions from normal steady-state operation to extreme fault disturbances. Their core value lies in improving energy utilization efficiency, achieving multi-energy complementarity, and overcoming the limitations of single-energy systems. However, multi-energy networks have significantly different structures and operating mechanisms, complex coupling relationships, and diverse fault propagation paths, resulting in safety risks far exceeding those of single-energy systems. Failure of the electricity-gas coupling can easily trigger large-scale cascading power outages, making safety assessment a necessity. Existing safety assessment technologies are mostly derived from traditional power systems, using steady-state energy flow models as their core, and can only achieve basic static and preliminary dynamic assessments. These technologies do not fully consider the unique characteristics of natural gas systems, such as transmission delays, pipeline gas storage, and dynamic pressure changes, nor can they comprehensively address the synergistic impact of electricity-gas network failures within a unified framework. Real-time assessments tend to be overly optimistic and lack accuracy, making it difficult to accurately identify system weaknesses and failing to meet the actual safety control and risk warning needs of integrated energy systems.

[0021] To address at least the aforementioned issues, a continuous power flow model of the integrated energy system is first constructed based on energy path theory, encompassing a steady-state AC power flow model for the power system and a dynamic gas flow model for the natural gas system. Next, an improved linear sensitivity analysis method is used to rapidly screen a pre-set N-1 fault set, eliminating faults with minimal impact and leaving a preliminary set of higher-risk faults. Then, a generalized curve fitting method is used to roughly calculate how much load the system can still support after these high-risk faults occur, yielding a load margin estimate. Based on this estimate, the most dangerous faults are further screened to form the final fault set. Finally, a dynamic continuous energy flow analysis method is used for a refined assessment, accurately identifying the system's critical vulnerable lines and their corresponding load margin indicators. This approach overcomes the limitations of traditional static models in depicting the dynamic differences of multi-energy systems, more realistically reflecting the system's response characteristics under faults. It solves the problems of overly optimistic approaches and insufficient dynamic response characterization in existing models, and collaboratively considers the impact of electrical and gas faults within a unified framework, gradually identifying critical vulnerable lines and load margin indicators, significantly improving the accuracy and reliability of the integrated energy system's safety assessment.

[0022] The following details a safety assessment method for integrated energy system planning based on energy path theory, as described in this invention. Please refer to [link / reference]. Figure 1 The method 100 includes steps 101 to 105:

[0023] Step 101: Construct a continuous power flow model for the integrated energy system based on energy path theory. The continuous power flow model includes a steady-state AC power flow model for the power system and a dynamic gas flow model for the natural gas system.

[0024] Step 102: Based on the continuous power flow model, the linear sensitivity analysis method is used to preliminarily screen the preset N-1 fault set by utilizing the singularity of the integrated energy system at the saddle-node bifurcation point, thus obtaining the preliminary fault set.

[0025] Step 103: Use the generalized curve fitting method to estimate the load margin of the preliminary fault set and obtain the load margin estimation result.

[0026] Step 104: Perform a second screening on the preliminary fault set based on the load margin estimation results to obtain the final fault set.

[0027] Step 105: Use the dynamic continuous energy flow analysis method to evaluate the final fault set to obtain the critical vulnerable lines of the integrated energy system and their corresponding load margin indices.

[0028] In one embodiment of the present invention, step 101 includes steps 1011 to 1014:

[0029] Step 1011: Construct a steady-state AC power flow model for the power system.

[0030] Since this invention focuses on system security assessment at the minute-level time scale, it explicitly excludes modeling of various transient processes in the power system. Therefore, the steady-state AC power flow model of the power system is as follows:

[0031]

[0032] In the formula, Represents a node The active power generated at that location Represents a node The required active power, This indicates the maximum load capacity index of the integrated energy system. This represents the change in the system's active power output. This represents the change in the system's active power load. Represents a node Voltage value, Represents a node Voltage value, The admittance of the network admittance matrix is ​​represented by the network admittance matrix. Represents a node Voltage phase angle, Indicates the phase angle of the node voltage. The inductive reactance term represents the network admittance matrix. Represents a node The reactive power generated at that location Represents a node The required reactive power at the location This represents the change in reactive load of the system. This represents the set of nodes in a power system.

[0033] Step 1012: Construct a dynamic gas flow model of the natural gas system based on the energy path theory.

[0034] Specifically, from a physical perspective, voltage and pressure, as state variables, can be defined as potential variables. Similarly, current and gas flow rate can be defined as flow variables. Based on energy path theory, natural gas pressure and flow rate are analogized to voltage and current, respectively. The pipeline is equivalent to a dynamic loop model composed of resistance, inductance, capacitance, and a controlled pressure source. A time-domain distributed parameter model of the gas network is established, specifically as follows:

[0035]

[0036] In the formula, This represents resistance and quantifies the frictional effect of the pipeline wall on the flow of natural gas. This represents the Darcy-Weisbach friction coefficient. Indicates the reference velocity of gas flow. Represents the cross-sectional area of ​​the pipe. Indicates the inner diameter of the pipe. Inductance is indicated, reflecting the inertial characteristics of natural gas during pipeline transportation. This represents capacitance, indicating the pipeline effect and reflecting the compressibility of natural gas. This represents the specific gas constant of natural gas. Indicates the temperature of natural gas. This represents a controlled pressure source, simulating the effect of changes in pipe slope and flow velocity on frictional losses. Represents gravitational acceleration. Indicates the pipe's angle of inclination;

[0037] The non-sinusoidal variables in the time domain of the gas network are decomposed into sinusoidal components of different frequencies using Fourier transform, resulting in a frequency-domain distributed parameter gas network model, specifically:

[0038]

[0039] In the formula, Represents angular frequency Lower time domain function , frequency components, Represents angular frequency. Represents angular frequency Lower time domain function , frequency components, represents an imaginary number;

[0040] Set intermediate parameters , And apply boundary conditions at the pipe inlet: and To set initial values ​​for the variable, the gas flow rate at the pipe outlet. and pressure The relationship between the inlet and outlet state variables can be solved using the following equation, which defines the two-port network as follows:

[0041]

[0042] In the formula, This indicates the gas pressure at the pipe inlet. This indicates the gas flow rate at the pipe inlet. , , , These are all network parameters. This represents the characteristic impedance of the pipe. , Indicates the length of the natural gas pipeline. This represents the propagation coefficient of the pipeline. ;

[0043] The two-port network is equivalently modeled as a frequency-domain lumped-parameter model of a gas circuit, and the expressions for its relevant lumped-parameter circuit components are as follows:

[0044]

[0045] In the formula, Indicates the branch impedance. This represents a controlled pressure source in the frequency domain. Indicates the grounding admittance at the first end. Indicates the end-ground admittance;

[0046] Based on the above natural gas pipeline model (including the time-domain distributed parameter model of the gas network, the frequency-domain distributed parameter gas network model, the two-port network, and the frequency-domain lumped parameter model of the gas circuit), any natural gas pipeline network can be described by the following branch equation:

[0047]

[0048] In the formula, Indicates the gas flow rate in the pipeline. This represents the branch admittance consisting of gas resistance, inductance, and capacitance. This indicates the pressure difference across the pipe. , This indicates the air pressure at the beginning of the pipeline. Indicates the air pressure at the end of the pipeline. These represent the parameters of the constant pressure source;

[0049] By extending the topological constraints of Kirchhoff's current law and voltage law for power grids to flow and potential energy limitations of gas systems, the gas network structure under the energy loop model is derived, as follows:

[0050]

[0051] In the formula, This represents the node association matrix of the gas pipeline network. This indicates that the node association matrix is ​​inverted. This represents the outgoing correlation matrix corresponding to the node correlation matrix of the gas pipeline network. Indicates gas node Pressure vector, Indicates gas node Flow vector Indicates the constant pressure source value. Represents the set of gas nodes;

[0052] By introducing a load growth factor at node n, a dynamic gas flow model for the natural gas system is derived based on the frequency domain distributed parameter gas network model, specifically as follows:

[0053]

[0054] In the formula, This represents the generalized nodal admittance matrix of a natural gas system. Indicates gas node The pressure vector, Indicates gas node The flow vector, This indicates the change in flow rate at the gas load node.

[0055] Based on this, the network equations for all frequency components are obtained, and then the frequency domain power flow solution is inversely transformed to the time domain. Finally, the dynamic power flow solution of the natural gas pipeline network is obtained by superimposing the solutions. Solving the above model can identify the weak links in the system.

[0056] As described above, given the inherently slow dynamic characteristics of natural gas systems, a system of partial differential equations incorporating the principles of mass and momentum conservation is typically used to accurately simulate the dynamic behavior of natural gas flow. To simplify the complexity of energy flow calculations and unify safety assessment indicators, a dynamic gas flow model for natural gas systems is established based on energy path theory. This model achieves a unified mathematical representation of the electrical and gas systems.

[0057] Step 1013: Based on the steady-state AC power flow model of the power system and the dynamic gas flow model of the natural gas system, construct a continuous power flow calculation model for the system, and construct a gas consumption model for the gas turbine.

[0058] Specifically, the continuous power flow calculation model for the system is as follows:

[0059]

[0060] In the formula, This represents a state vector, containing node voltage and gas pressure vectors. Indicates the line Maximum carrying capacity of the integrated energy system under fault conditions System-specific parameters representing faulty lines, covering power system branches and natural gas pipelines, such as parameters of disconnected lines (including line admittance, reactance, and gas admittance). A vector representing the change in node energy injection. This represents a function that includes the steady-state AC power flow model of the power system and the dynamic gas flow model of the natural gas system.

[0061] As a crucial coupling link between the power system and the natural gas system, the gas turbine converts fuel transported by the natural gas network into electrical energy, thereby realizing energy transfer from the gas network to the power grid and establishing a direct operational link between the two energy systems. The specific gas consumption model for the gas turbine is as follows:

[0062]

[0063] In the formula, Indicates that it is located at node The gas consumption of the gas turbine. Indicates the density of the gas. Indicates calorific value. This indicates the efficiency of the gas turbine. Represented as busbar in a power system The amount of electricity generated by the generator.

[0064] Step 1014: Obtain the continuous power flow model of the integrated energy system based on the continuous power flow calculation model of the system and the gas consumption model of the gas turbine.

[0065] As described above, based on energy path theory, the steady-state AC power flow of electricity and the dynamic gas flow of natural gas are organically integrated. At the same time, a gas turbine gas consumption model is introduced to achieve a precise characterization of the electro-gas coupling characteristics. This not only preserves the accuracy of steady-state calculations of the power system, but also fully reflects the dynamic inertia, gas storage, and resistance characteristics of natural gas pipelines. It breaks through the limitations of traditional static models in representing the dynamic differences of multi-energy systems, and constructs a comprehensive continuous energy flow model that is more in line with the actual operating mechanism. This lays a reliable foundation for subsequent fault screening and accurate load margin calculation, and effectively improves the authenticity and accuracy of safety assessment.

[0066] In one embodiment of the present invention, step 102 includes steps 1021 to 1023:

[0067] Step 1021: Based on the continuous power flow model, the load margin deviation caused by each faulty line in the preset N-1 fault set is calculated using the linear sensitivity analysis method by taking advantage of the singularity of the integrated energy system at the saddle-node bifurcation point, and used as the sensitivity value.

[0068] Specifically, the continuous power flow calculation model of the system is linearized by performing a first-order Taylor expansion near the operating point to obtain the linearized continuous power flow calculation model of the system, as follows:

[0069]

[0070] In an integrated electric-gas energy system, the collapse point typically manifests as the voltage of the power system approaching its stability limit or the pressure of the natural gas system dropping to zero, indicating that the system has reached a saddle-node bifurcation point. At this point, the Jacobian matrix exhibits singularity, producing zero eigenvalues ​​and non-zero left eigenvectors. ,satisfy ;

[0071] Based on the linearized continuous power flow calculation model of the system, the load margin change caused by the disconnection of each faulty line in the preset N-1 fault set is calculated using the singularity of the saddle-node bifurcation point. Specifically:

[0072]

[0073] In the formula, This represents the load margin value of the state vector at the saddle-node bifurcation point. This represents the load margin value at the saddle-node bifurcation point in the ground state. The derivation process is as follows:

[0074]

[0075]

[0076]

[0077] In the formula, Represents a node Change in active power Indicates a branch State variables, Indicates a branch Electrical conductivity Indicates a branch Saturation Indicates a branch Saturation to ground Represents a node voltage amplitude, Represents a node voltage amplitude, Represents a node With nodes The phase angle difference, Indicates the node under the reference operating condition To the node Active power flow, Represents a node Reactive power change Indicates the node under the reference operating condition To the node reactive power flow, Represents a node air pressure value Represents a node air pressure value Indicates gas network Pipe admittance, Indicates the node under the reference working condition Square of gas pressure at nodes The product of the gas flow rates; Represents a node The change in Z-value for an electro-pneumatic coupling node:

[0078]

[0079] In the formula, Indicates the line Before the break, the node Flow to Node The active power of the branch circuit, Represents the node The change in Z-value;

[0080] set up Based on the aforementioned load margin change, the load margin deviation caused by each faulty line is derived and used as a sensitivity value, specifically:

[0081]

[0082] In the formula, Indicates the faulty line The resulting load margin deviation Represents a node Active power at point, Represents a node reactive power, Represents a node Active power at point, Represents a node reactive power, Indicates the node under the reference operating condition To the node Active power flow, Indicates the node under the reference operating condition To the node reactive power flow, Represents a node Expand gas flow rate at the location, Represents a node Expand gas flow rate at the location, Indicates the node under the reference working condition Square of gas pressure at nodes The product of gas flow rates.

[0083] The calculated sensitivity value is negatively correlated with the severity of the fault; that is, the more negative the sensitivity value, the higher the risk of line fault. Therefore, lines with high sensitivity values ​​will be included in the next stage for further evaluation.

[0084] Step 1022: Sort the faulty lines according to the sensitivity values ​​from smallest to largest to obtain the first sorted faulty lines.

[0085] Step 1023: Select the first preset number of fault lines from the first sorted fault lines to obtain a preliminary fault set.

[0086] As described above, unlike traditional sensitivity analysis methods, the linear sensitivity analysis method of this invention utilizes the singularity of the electric-gas integrated energy system at the saddle-node bifurcation point to derive a rapid load margin calculation formula, thereby improving the efficiency of preliminary screening while ensuring accuracy.

[0087] In one embodiment of the present invention, step 103 includes steps 1031 to 1033:

[0088] Step 1031: For each fault line in the initial fault set, select the load bus with the largest change in state variables and fit the electrical load-voltage (PV) curve and the gas load-pressure (LP) curve.

[0089] Among them, the load bus The selection criteria are:

[0090]

[0091] In the formula, Indicates the rate of change of load. express corresponding nodes State variables, express corresponding nodes State variables.

[0092] Step 1032: Solve for parameters using the improved generalized curve fitting method based on the electrical load-voltage curve and the gas load-pressure curve. , , .

[0093] Specifically, based on the electrical load-voltage curve and the gas load-pressure curve The three points obtained from the power flow calculation ( , ), ( , ), ( , Substitute into the curve, , , For state variables, , , To determine the load margin, the following three equations are obtained. The parameters are then solved using the improved generalized curve fitting method. , , :

[0094]

[0095] Step 1033: Based on the differences in physical characteristics between the power system and the natural gas system at the saddle-node bifurcation point, estimate the load margin of the power system and the load margin of the natural gas system at the saddle-node bifurcation point based on the parameters, and obtain the load margin estimation results.

[0096] Specifically, in a power system, when the voltage approaches the saddle-node bifurcation point, the rate of voltage change approaches infinity. At this point, the state variable can be set as... Substituting this value into the quadratic fitting model, the load margin of the power system at the saddle-node bifurcation point can be obtained:

[0097]

[0098] In a natural gas system, the pressure at the saddle-node bifurcation point drops to zero. By substituting x=0 into the corresponding fitted curve, the load margin of the natural gas system at the saddle-node bifurcation point can be calculated.

[0099] .

[0100] As described above, the traditional generalized curve fitting method suffers from large fitting errors and insufficient critical point characterization in highly nonlinear operating ranges. The improved generalized curve fitting method of this invention enhances the model's ability to characterize the evolution of load margin by optimizing the fitting expression and increasing the sensitivity of the parameter solution process to key sample points. Its effect is to more accurately approximate the load limit position of the system, improve the reliability of expected fault screening and ranking results, reduce the number of repeated precise calculations, and improve the overall evaluation efficiency.

[0101] In one embodiment of the present invention, step 104 includes steps 1041 to 1042:

[0102] Step 1041: Sort the faulty lines in the preliminary fault set according to the load margin estimation results from smallest to largest to obtain the second sorted faulty lines.

[0103] Step 1042: Select the first second preset number of fault lines from the second sorted fault lines to obtain the final fault set.

[0104] In an alternative implementation, load margin parameters under various operating conditions can also be recorded to provide a data basis for subsequent calculations.

[0105] As described above, by sorting the load margin estimation results, it is possible to accurately and quickly identify the critical and vulnerable lines that have a significant impact on the system.

[0106] In one embodiment of the present invention, step 105 includes steps 1051 to 1053:

[0107] Step 1051: For each faulty line in the final fault set, use the dynamic continuous energy flow analysis method to simulate the dynamic process of gradual load increase and track the real-time response of the integrated energy system.

[0108] Step 1052: Using an adaptive algorithm, with the estimated load margin as the initial value, iteratively optimize until convergence to the accurate maximum load margin.

[0109] Step 1053: The faulty line is designated as a critical and vulnerable line, and the maximum load margin of the faulty line is used as a load margin index.

[0110] When accurately calculating load margin, the initial load setting does not depend on the baseline load.

[0111] As described above, the dynamic continuous energy flow analysis method and adaptive algorithm can accurately identify the maximum load margin of the system and eliminate redundant calculations of the baseline load, thus significantly reducing computational complexity.

[0112] In one embodiment of the present invention, after step 105, the method further includes:

[0113] Step 106: The critical vulnerable lines and their corresponding load margin indicators are incorporated into the planning process of the integrated energy system as the basis for planning correction.

[0114] Specifically, firstly, based on the load margin indicators and fault severity of each critical and vulnerable line, the vulnerable areas in the integrated energy system are located and classified. Then, for critical and vulnerable lines and their associated nodes with low load margins and significant fault impacts, priority is given to implementing measures such as line capacity expansion, parallel channel addition, network topology optimization, and local reinforcement of source, load, and storage resources during the planning stage to improve the energy supply support capacity and energy flow transfer capacity of the area under fault conditions. At the same time, the improvement effect of the load margin of critical and vulnerable lines is used as the criterion for judging the merits of the planning scheme. Different candidate planning schemes are compared and selected, and the planning scheme that can effectively improve the load margin of critical and vulnerable lines and reduce the overall vulnerability of the system is given priority.

[0115] As described above, incorporating critical and vulnerable lines and their corresponding load margin indicators as the basis for planning corrections into the planning process of an integrated energy system enables weak points in the system to be identified in advance during the planning stage and reinforced in a targeted manner. This reduces operational risks after the system is built and improves the overall safety, reliability, and energy supply security of the system.

[0116] Please refer to Figure 2 The present invention also provides a safety assessment system 200 based on energy path theory for integrated energy system planning, including a memory 201, a processor 202, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the various steps of the safety assessment method for integrated energy system planning based on energy path theory as described above.

[0117] In summary, the safety assessment method and system for integrated energy system planning based on energy path theory described above can conduct a unified analysis of the energy transmission status and node operation status of the system under fault conditions from the overall perspective of the coordinated operation of the power system and the natural gas system, thereby more comprehensively and realistically reflecting the actual operating characteristics of the integrated energy system. By assessing the changes in system energy supply capacity under different fault scenarios, this invention can more accurately identify the critical paths affecting the safe operation of the system, avoiding the bias caused by relying solely on local indicators or single network analysis, thus improving the credibility and engineering reference value of the safety assessment results. In addition, when applied to system planning, it can provide planners with more targeted decision-making basis, enabling planning schemes to not only focus on economy and energy supply demand, but also pay more attention to the system's safety and risk resistance under fault disturbances, thereby helping to improve the rationality, foresight, and practicality of integrated energy system planning results. At the same time, this invention also has significant advantages in assessment efficiency. For integrated energy systems, the number of preset fault scenarios is large and the coupling relationships are complex. If high-precision analysis is performed on all scenarios one by one, it often leads to a large amount of computation and a long assessment cycle, making it difficult to meet the application requirements of multi-scheme comparison and repeated verification in the planning stage. This invention, by constructing a clearly hierarchical evaluation process, can significantly reduce unnecessary repetitive calculations, improve the overall evaluation speed, shorten the analysis time, and reduce implementation costs while ensuring that key failure scenarios are effectively identified. It can better balance the relationship between evaluation accuracy and evaluation efficiency, thereby improving the ability to identify system vulnerabilities and enhancing the applicability of the method in large-scale integrated energy system planning.

[0118] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A safety assessment method for integrated energy system planning based on energy path theory, characterized in that, include: A continuous power flow model for a comprehensive energy system is constructed based on energy path theory. The continuous power flow model includes a steady-state AC power flow model for the power system and a dynamic gas flow model for the natural gas system. Based on the continuous power flow model, the linear sensitivity analysis method is used to preliminarily screen the preset N-1 fault set by utilizing the singularity of the integrated energy system at the saddle-node bifurcation point to obtain the preliminary fault set. The load margin of the preliminary fault set is estimated using the generalized curve fitting method, and the load margin estimation result is obtained. The preliminary fault set is further filtered based on the load margin estimation results to obtain the final fault set. The final fault set is evaluated using a dynamic continuous energy flow analysis method to obtain the critical vulnerable lines of the integrated energy system and their corresponding load margin indices. The dynamic gas flow model of the natural gas system constructed based on energy path theory includes: Based on energy path theory, natural gas pressure and flow rate are analogized to voltage and current, respectively. The pipeline is equivalent to a dynamic loop model consisting of resistance, inductance, capacitance, and a controlled pressure source. A time-domain distributed parameter model of the gas network is established, specifically as follows: In the formula, Indicates resistance. This represents the Darcy-Weisbach friction coefficient. Indicates the reference velocity of gas flow. Represents the cross-sectional area of ​​the pipe. Indicates the inner diameter of the pipe. Indicates inductance. Indicates capacitance. This represents the specific gas constant of natural gas. Indicates the temperature of natural gas. Indicates a controlled stress source. Represents gravitational acceleration. Indicates the pipe inclination angle. This indicates the maximum load capacity of the integrated energy system. The non-sinusoidal variables in the time domain of the gas network are decomposed into sinusoidal components of different frequencies using Fourier transform, resulting in a frequency-domain distributed parameter gas network model, specifically: In the formula, Represents angular frequency Lower time domain function , frequency components, Represents angular frequency. Represents angular frequency Lower time domain function , frequency components, represents an imaginary number; By introducing a load growth factor at node n, a dynamic gas flow model for the natural gas system is derived based on the frequency domain distributed parameter gas network model, specifically as follows: In the formula, This represents the generalized nodal admittance matrix of a natural gas system. Indicates gas node The pressure vector, Indicates gas node The flow vector, This indicates the change in flow rate at the gas load node.

2. The safety assessment method for integrated energy system planning based on energy path theory according to claim 1, characterized in that, The continuous power flow model of a comprehensive energy system based on energy path theory includes: Construct a steady-state AC power flow model for the power system; A dynamic gas flow model of a natural gas system is constructed based on energy path theory; Based on the steady-state AC power flow model of the power system and the dynamic gas flow model of the natural gas system, a continuous power flow calculation model of the system is constructed, and a gas consumption model of the gas turbine is also constructed. The continuous power flow model of the integrated energy system is obtained based on the continuous power flow calculation model of the system and the gas consumption model of the gas turbine.

3. The safety assessment method for integrated energy system planning based on energy path theory according to claim 2, characterized in that, Constructing a steady-state AC power flow model for the power system, specifically: In the formula, Represents a node The active power generated at that location Represents a node The required active power, This indicates the maximum load capacity index of the integrated energy system. This represents the change in the system's active power output. This represents the change in the system's active power load. Represents a node Voltage value, Represents a node Voltage value, The admittance of the network admittance matrix is ​​represented by the network admittance matrix. Represents a node Voltage phase angle, Represents a node Voltage phase angle, The inductive reactance term represents the network admittance matrix. Represents a node The reactive power generated at that location Represents a node The required reactive power at the location This represents the change in reactive load of the system. This represents the set of nodes in a power system.

4. The safety assessment method for integrated energy system planning based on energy path theory according to claim 2, characterized in that, Based on the continuous power flow model, the linear sensitivity analysis method is used to initially screen the preset N-1 fault set using the singularity of the integrated energy system at the saddle-node bifurcation point. The preliminary fault set includes: Based on the continuous power flow model, the load margin deviation caused by each faulty line in the preset N-1 fault set is calculated using the linear sensitivity analysis method by taking advantage of the singularity of the integrated energy system at the saddle-node bifurcation point, and used as the sensitivity value. The faulty lines are sorted in ascending order of their sensitivity values ​​to obtain the first sorted faulty lines. Select the first preset number of faulty lines from the first sorted faulty lines to obtain a preliminary fault set.

5. A safety assessment method for integrated energy system planning based on energy path theory according to claim 4, characterized in that, Based on the continuous power flow model, the load margin deviation caused by each faulty line in the preset N-1 fault set is calculated using linear sensitivity analysis, taking advantage of the singularity of the integrated energy system at the saddle-node bifurcation point. This deviation is used as the sensitivity value, including: The system continuous power flow calculation model is linearized by performing a first-order Taylor expansion near the operating point to obtain the linearized system continuous power flow calculation model. Based on the linearized system continuous power flow calculation model, the load margin change caused by the disconnection of each fault line in the preset N-1 fault set is calculated by utilizing the singularity of the saddle-node bifurcation point. The load margin deviation caused by each faulty line is derived based on the load margin change and used as a sensitivity value.

6. The safety assessment method for integrated energy system planning based on energy path theory according to claim 1, characterized in that, The load margin of the preliminary fault set is estimated using the generalized curve fitting method, and the load margin estimation results include: For each faulty line in the initial fault set, select the load bus with the largest change in state variables and fit the electrical load-voltage curve and the gas load-pressure curve. The parameters are solved using an improved generalized curve fitting method based on the electrical load-voltage curve and the gas load-pressure curve. Based on the differences in physical characteristics between the power system and the natural gas system at the saddle-junction bifurcation point, the load margins of the power system and the natural gas system at the saddle-junction bifurcation point are estimated using the parameters mentioned above, resulting in load margin estimation results.

7. A safety assessment method for integrated energy system planning based on energy path theory according to claim 1, characterized in that, The preliminary fault set is further filtered based on the load margin estimation results to obtain the final fault set, which includes: The fault lines in the initial fault set are sorted in ascending order of the load margin estimation results to obtain the second sorted fault lines. Select the first second preset number of fault lines from the second sorted fault lines to obtain the final fault set.

8. A safety assessment method for integrated energy system planning based on energy path theory according to claim 1, characterized in that, The final fault set was evaluated using a dynamic continuous energy flow analysis method, resulting in the following key vulnerable lines of the integrated energy system and their corresponding load margin indices: For each faulty line in the final fault set, a dynamic continuous energy flow analysis method is used to simulate the dynamic process of gradual load increase and track the real-time response of the integrated energy system. An adaptive algorithm is used, with the estimated load margin as the initial value, to iteratively optimize until it converges to the accurate maximum load margin. The faulty line is designated as a critical and vulnerable line, and the maximum load margin of the faulty line is used as a load margin indicator.

9. A safety assessment system for integrated energy system planning based on energy path theory, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements each step of the safety assessment method for integrated energy system planning based on energy path theory as described in any one of claims 1 to 8.

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