Heavy haul railway coupling system small signal stability analysis method, device, equipment and medium

Abstract

The invention relates to a heavy haul railway coupling system small signal stability analysis method and device, computer equipment, a computer readable storage medium and a computer program product. The method comprises the following steps: acquiring a working diagram of a heavy haul train in a coupling system of the heavy haul railway, an operation mode of a traction network in the heavy haul railway and a connection scheme of a traction transformer; respectively constructing impedance models of a traction transformer, a traction network, an energy storage device and a heavy haul train in the coupling system; equivalently simplifying the coupling system based on the running diagram and impedance models of a traction transformer, a traction network, an energy storage device and a heavy-load train in the coupling system to obtain an impedance equivalent model of the coupling system; and based on the impedance equivalent model of the coupling system, performing small signal stability analysis on the coupling system according to a preset stability criterion, the running diagram, the running mode and the connection scheme. By adopting the method, the problem of small signal stability evaluation of the heavy haul railway coupling system can be effectively solved.

Description

Technical Field

[0001] This application relates to the field of stability analysis technology for rail transit, and in particular to a method, apparatus, computer equipment, computer-readable storage medium, and computer program product for small-signal stability analysis of a heavy-haul railway coupling system. Background Technology

[0002] With the development of railways, heavy-haul trains have become an important part of land freight transportation due to their high cost-effectiveness and fast transport speed. Their advantages in long-distance, large-scale material transport are becoming increasingly apparent. However, the high power and large fluctuations of heavy-haul trains, coupled with the low power density of batteries, limit their widespread application. Supercapacitors, as energy storage components, have the advantages of high power density and extremely long cycle life. Connecting supercapacitors to the traction power supply system of heavy-haul trains as energy storage devices can provide power while reducing energy loss, effectively solving the challenges of energy storage in heavy-haul trains.

[0003] However, the integration of energy storage devices brings new challenges, especially when integrated into complex "source-grid-storage-vehicle" coupled systems. This introduces multiple converters, complicating converter interactions, increasing system instability, and causing low-frequency oscillations. These problems not only affect the safe operation of heavy-haul railways but may also adversely impact overall transportation efficiency and costs.

[0004] Given the significant differences between heavy-haul trains and traditional high-speed trains in terms of power supply architecture and train formation, the interactions between various components within the "source-grid-storage-vehicle" coupled system of heavy-haul railways become more intricate. This characteristic presents new challenges for small-signal analysis methods in assessing system stability. Therefore, in-depth exploration of the intrinsic relationships within the "source-grid-storage-vehicle" coupled system of heavy-haul railways and the proposal of a small-signal stability analysis method suitable for this system are crucial for ensuring the stable operation of the entire system and the safe and reliable operation of heavy-haul railways. Summary of the Invention

[0005] Therefore, it is necessary to provide a method, apparatus, computer equipment, computer-readable storage medium, and computer program product for small-signal stability analysis of heavy-haul railway coupled systems, which can perform stability analysis on heavy-haul railways, in response to the above-mentioned technical problems.

[0006] Firstly, this application provides a method for small-signal stability analysis of a heavy-haul railway coupling system, including:

[0007] To obtain the train operation diagram of heavy-haul railway in the coupling system, the operation mode of the traction network in heavy-haul railway, and the connection scheme of traction transformer;

[0008] Impedance models of the traction transformer, traction network, energy storage device, and heavy-haul train in the coupling system are constructed respectively.

[0009] Based on the operation diagram and the impedance models of the traction transformer, traction network, energy storage device and heavy-haul train in the coupling system, the coupling system is simplified by equivalent means to obtain the impedance equivalent model of the coupling system.

[0010] Based on the impedance equivalent model of the coupled system, and according to the preset stability criteria, as well as the operation diagram, the operation mode, and the connection scheme, a small-signal stability analysis is performed on the coupled system.

[0011] Secondly, this application also provides a small-signal stability analysis device for a heavy-haul railway coupling system, comprising:

[0012] The acquisition module is used to acquire the train operation diagram of heavy-haul trains in the coupling system of heavy-haul railway, the operation mode of the traction network in heavy-haul railway, and the connection scheme of traction transformers.

[0013] The construction module is used to construct the impedance models of the traction transformer, traction network, energy storage device and heavy-haul train in the coupled system, respectively.

[0014] The simplification module is used to perform equivalent simplification of the coupled system based on the operation diagram and the impedance models of the traction transformer, traction network, energy storage device and heavy-haul train in the coupled system, so as to obtain the impedance equivalent model of the coupled system.

[0015] The analysis module is used to perform small-signal stability analysis on the coupled system based on the impedance equivalent model of the coupled system, according to the preset stability criteria, as well as the operation diagram, the operation mode and the connection scheme.

[0016] Thirdly, this application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method described in the first aspect.

[0017] Fourthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described in the first aspect.

[0018] Fifthly, this application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the method described in the first aspect.

[0019] The aforementioned methods, devices, computer equipment, computer-readable storage media, and computer program products for small-signal stability analysis of heavy-haul railway coupling systems, by closely integrating actual operational data (operation diagrams, operating modes, and connection schemes), meticulously construct dynamic impedance models of key components (especially heavy-haul trains and energy storage devices), and utilize stability criteria based on impedance equivalent models for multi-scenario analysis. This effectively solves the challenge of assessing the small-signal stability (especially low-frequency oscillations) of this complex coupled system of heavy-haul railways. It significantly improves the accuracy, relevance, and comprehensiveness of small-signal stability analysis of heavy-haul train coupling systems, ultimately providing powerful theoretical tools and decision-making basis for the safe and stable operation, optimized design, and control of the system, enabling proactive prevention and improving the power supply reliability and transportation efficiency of heavy-haul railways. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart illustrating a small-signal stability analysis method for a heavy-haul railway coupling system in one embodiment.

[0022] Figure 2 This is a schematic diagram of the process for obtaining the traction network impedance model in one embodiment;

[0023] Figure 3 This is a schematic diagram of the "source-grid-storage-vehicle" coupled system of a heavy-haul railway in another embodiment;

[0024] Figure 4 The diagram shows the V / X traction transformer connection and equivalent circuit of the "source-grid-storage-vehicle" coupling system of a heavy-haul railway in one embodiment.

[0025] Figure 5 The Scott traction transformer connection and equivalent circuit diagram of a "source-grid-storage-vehicle" coupled system for a heavy-haul railway in one embodiment;

[0026] Figure 6 This is a schematic diagram of the energy storage device topology and control strategy block diagram of a "source-grid-storage-vehicle" coupled system for a heavy-haul railway in one embodiment;

[0027] Figure 7 This is a schematic diagram of the heavy-haul train topology and control strategy block diagram of the "source-network-storage-vehicle" coupled system of a heavy-haul railway in one embodiment;

[0028] Figure 8 This is a schematic diagram showing the impedance simulation results and theoretical derivation results of a heavy-haul train in one embodiment;

[0029] Figure 9 This is a schematic diagram of the impedance simulation and derivation results of an energy storage device in one embodiment;

[0030] Figure 10 The Nyquist plot of a "source-grid-storage-vehicle" coupled system for a heavy-haul railway in one embodiment;

[0031] Figure 11 Nyquist plots of the "source-grid-storage-vehicle" coupling system of a heavy-haul railway under different operating conditions in one embodiment;

[0032] Figure 12 This is a structural block diagram of a small-signal stability analysis device for a heavy-haul railway coupling system in one embodiment;

[0033] Figure 13 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0035] It should be noted that the terms "first," "second," etc., used in this application may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from the second element. The terms "comprising" and "having," and any variations thereof, used in this application, are intended to cover non-exclusive inclusion. The term "multiple" used in this application refers to two or more.

[0036] In one embodiment, such as Figure 1 As shown, a method for small-signal stability analysis of a heavy-haul railway coupling system is provided. This embodiment illustrates the method by applying it to a server. It is understood that this method can also be applied to a terminal, or to a system including both a terminal and a server, and implemented through interaction between the terminal and the server. In this embodiment, the method includes the following steps:

[0037] Step S202: Obtain the operation diagram of heavy-haul trains in the coupling system of heavy-haul railway, the operation mode of traction network in heavy-haul railway, and the connection scheme of traction transformer.

[0038] The heavy-haul railway coupling system refers to an integrated system formed by the mutual influence and close connection between the electric traction power supply system (including traction transformers, traction network, energy storage devices, etc.) and the electric traction load (heavy-haul trains). Heavy-haul trains obtain electrical energy from the traction network for propulsion, and their operating state (location, power demand) in turn affects the voltage and current stability of the traction network. Small-signal stability analysis is a theoretical method for analyzing whether a dynamic system can recover to its original equilibrium state or enter another stable state after being subjected to small disturbances (such as small load fluctuations or small voltage changes). It is used to focus on the dynamic response characteristics of the system near the equilibrium point. In power systems, it is used to determine whether the system will experience low-frequency oscillations, voltage instability, or other problems. A train timetable is a detailed plan chart specifying the time, location, speed, and stops of heavy-haul trains on the railway line. The timetable determines the spatial and temporal distribution of trains and the changes in their power demand. The traction network refers to the power supply network that provides electricity to electric locomotives or EMUs. It typically includes the overhead contact line, rails (or dedicated return lines), and related supporting structures and sectional insulators, serving as the channel for transmitting electrical energy from the traction substation to the train. Operating mode refers to the working state of the traction network during a specific time period or section; different operating modes affect the network topology and impedance. A traction transformer is a transformer within the traction substation used to step down and convert electrical energy from the external high-voltage transmission network to a voltage level suitable for traction loads. The connection scheme refers to the connection method between the primary and secondary windings of the traction transformer, which determines the number of phases, phase relationship, harmonic content, and equivalent impedance characteristics to the power grid.

[0039] For example, the server can obtain the train schedule of heavy-haul trains from the railway dispatching system, obtain the current traction network operation mode from the traction power supply system, and obtain the specific connection scheme of traction transformers from the relevant systems of traction substations.

[0040] Step S204: Construct impedance models for the traction transformer, traction network, energy storage device, and heavy-haul train in the coupled system, respectively.

[0041] Impedance model refers to a mathematical model used to describe the voltage-current response relationship of electrical equipment or network at a specific frequency. Energy storage device refers to energy storage equipment installed in the traction power supply system. In heavy-haul trains, the energy storage device can be a supercapacitor, which can be used to provide instantaneous power support, regenerative braking energy recovery, stabilize grid voltage, and improve power quality.

[0042] For example, the server can establish an equivalent impedance model of the traction transformer based on the connection scheme of the traction transformer; it can establish an equivalent impedance model based on the physical structure and operation mode of the traction network; it can establish an equivalent impedance model based on the type of energy storage device (such as supercapacitor) and control system (such as DC / DC converter or DC / AC converter and control strategy); it can also construct an equivalent impedance model of the heavy-haul train based on the transmission system of the heavy-haul train and the operation diagram.

[0043] Step S206: Based on the operation diagram and the impedance models of the traction transformer, traction network, energy storage device and heavy-haul train in the coupled system, the coupled system is simplified by equivalent means to obtain the impedance equivalent model of the coupled system.

[0044] Equivalent simplification refers to the process of simplifying a complex coupled system containing multiple components into one or more equivalent impedances or equivalent circuit models using circuit theory. An impedance equivalent model is a simplified impedance network model obtained after equivalent simplification, which represents the dynamic characteristics of the entire coupled system.

[0045] For example, after constructing the impedance models of each independent component in step S204, the server can connect them into a complete coupled system circuit model, i.e., the impedance equivalent model of the coupled system, based on their physical connection relationship (topology) and the position of the heavy-load train at a specific moment specified in the timetable.

[0046] Step S208: Based on the impedance equivalent model of the coupled system, and according to the preset stability criteria, as well as the operation diagram, operation mode and connection scheme, perform small-signal stability analysis on the coupled system.

[0047] The preset stability criterion can refer to a theoretical criterion used to determine whether a system based on an impedance equivalent model is small-signal stable, such as the Nyquist criterion.

[0048] For example, the server can perform small-signal stability analysis on the impedance equivalent model of the coupled system based on preset stability criteria, combined with the operation diagram, operation mode and connection scheme.

[0049] The aforementioned method for analyzing the small-signal stability of heavy-haul railway coupled systems, by closely integrating actual operational data (operation diagrams, operating modes, and connection schemes), refines the dynamic impedance models of key components (especially heavy-haul trains and energy storage devices). Furthermore, it employs stability criteria based on impedance equivalent models for multi-scenario analysis, effectively solving the challenge of assessing the small-signal stability (especially low-frequency oscillations) of this complex coupled system. This significantly improves the accuracy, relevance, and comprehensiveness of small-signal stability analysis for heavy-haul train coupled systems, ultimately providing powerful theoretical tools and decision-making support for the safe and stable operation, optimized design, and control of the system. This enables proactive prevention and enhances the power supply reliability and transportation efficiency of heavy-haul railways.

[0050] In one exemplary embodiment, such as Figure 2 As shown, the steps for constructing the impedance model of the traction network include:

[0051] Step S302: When the traction network is in full parallel operation, the contact network current, track current, uplink positive feeder current and downlink track current are analyzed by the generalized connection method of adjacent locomotives and traction substations to determine the downlink contact network current and positive feeder current.

[0052] The traction network operation modes include full parallel operation, end-parallel operation, and non-parallel operation. The generalized connection method between adjacent locomotives and traction substations refers to a method specifically used to analyze the current distribution of complex traction networks (especially full parallel mode) based on multi-conductor transmission line theory and Kirchhoff's laws.

[0053] Step S304: Obtain the voltage drop expressions for the three closed circuits between the uplink and downlink contact networks, the positive feeder, and the track.

[0054] Step S306: Based on the current of the downlink contact network, the current of the positive feeder, and the voltage drop expression, the impedance model of the traction network is obtained.

[0055] For example, the steps of the server constructing the impedance model of the traction network may include: for a fully parallel traction network, the impedances of the T, R, and F lines are respectively... , and The mutual impedances between lines T, R, and F are respectively , and The length of the AT section where the locomotive is located is D, and the distance from the locomotive's short-circuit point to the previous AT section is x. Let x represent the current at point x, and let x represent the traction current of the locomotive. When a short circuit occurs in the upstream section of the overhead contact line, the contact line current can be analyzed using the generalized connection method of nearby locomotives and traction substations. Track current Upward positive feeder current and down-track current This allows us to determine the current in the downlink contact network and the positive feeder. During normal operation of the fully parallel traction network, three closed circuits are established between the uplink and downlink contact networks, the positive feeder, and the track. The voltage drop equations for these three circuits are as follows:

[0056]

[0057] The traction network current in fully parallel operation can be written in the following form:

[0058]

[0059] Based on the above formula, the impedance model of the traction network in the fully parallel operation mode can be calculated, and its expression is as follows:

[0060]

[0061]

[0062]

[0063] The length of the power supply arm is l.

[0064] In other embodiments, the impedance model construction process for traction networks operating in parallel and non-parallel at the end can refer to the above process.

[0065] In this embodiment, by applying the generalized connection method to accurately solve the current distribution in the complex scenario of a fully parallel traction network, and constructing an impedance model based on the voltage drop equations of the three core physical circuits, the challenge of high-precision traction network impedance modeling under this mode was successfully solved. This significantly improves the model's fidelity in the fully parallel operation mode, accurately characterizes the coupling effects of multiple vehicles operating in close proximity under heavy loads, provides a tool for quantitatively evaluating the stability of the fully parallel mode, and ultimately solidifies the credibility and practical value of the overall system-level small-signal stability analysis results.

[0066] In an exemplary embodiment, the steps of constructing the impedance model of the energy storage device include: injecting a first preset small-signal voltage disturbance into the AC side of the energy storage device to obtain the phase voltage, phase current, and DC side voltage; obtaining the modulation signal expression of the single-phase voltage converter in the energy storage device based on the phase voltage, phase current, and DC side voltage; obtaining the circuit expression of the energy storage device; and obtaining the impedance model of the energy storage device based on the modulation signal expression of the single-phase voltage converter in the energy storage device and the circuit expression of the energy storage device.

[0067] The first preset small-signal voltage disturbance can refer to a small voltage change whose amplitude is much smaller than the normal operating voltage of the energy storage device. The purpose is not to change the main operating point of the energy storage device, but only to stimulate its linear dynamic response under small disturbance.

[0068] For example, the steps of a server constructing an impedance model of an energy storage device may include: firstly injecting a small-signal voltage disturbance into the AC side. (First preset small-signal voltage disturbance) When a disturbance voltage with a frequency of fp+f1 is injected into the system, the corresponding signal frequency is fp-f1. The signal with a frequency of fp+f1 is called the "positive mirror frequency" signal, and the signal with a frequency of fp-f1 is called the "negative mirror frequency" signal. In this embodiment, the small-signal voltage disturbance injected into the AC side is:

[0069]

[0070]

[0071] Among them, the above-mentioned small-signal voltage disturbances include both incremental and decremental disturbances; and This represents the amplitude and phase of the voltage disturbance at the corresponding positive mirror frequency.

[0072] Then calculate the phase voltage. Current and DC side voltage Their expressions are as follows:

[0073]

[0074]

[0075]

[0076] in, and The amplitude and phase of the fundamental voltage at frequency f1; and The amplitude and phase of the voltage disturbance corresponding to the positive mirror frequency; and The definition of current follows the same rules for the amplitude and phase of voltage disturbances corresponding to negative mirror frequencies; Indicates the DC voltage amplitude. and This represents the voltage amplitude and phase corresponding to the disturbance frequency fp.

[0077] In this embodiment, SOGI_PLL is used to track phase voltage. The phase can also be tracked using other methods to obtain... and The frequency domain expression is then derived, and the output of the DC bus voltage control loop is obtained. The expression is used to derive the modulation signal of the single-phase voltage converter. The expression. Here, SOGI_PLL can refer to (Second-Order Generalized Integrator_Phase-Locked Loop). The single-phase voltage converter of the energy storage device uses an indirect current control method in the dq domain, requiring the voltage and current under phases α and β to be transformed to the dq coordinate system. The control loop of the single-phase voltage converter consists of a voltage control loop and a current control loop. Voltage control uses a proportional-integral controller to ensure a constant DC bus voltage. The modulation signal of the single-phase voltage converter. The expression is as follows:

[0078]

[0079] in, , For the output variable of the current control loop, symbol This represents convolution.

[0080] Finally, based on the circuit topology of the energy storage device, the circuit equation expression is derived. Substituting the variables mentioned above into the equation expression, the expression for each impedance (the impedance model of the energy storage device) is derived as follows:

[0081]

[0082] Wherein, the subscript p represents the system response when the positive mirror frequency is injected, the subscript n represents the system response when the negative mirror frequency is injected, Zpp represents the positive sequence impedance of the energy storage device, Zpn and Znp represent the coupling impedance between their positive and negative sequences, and Znn represents the negative sequence impedance. , , , This is a complex frequency domain expression.

[0083] In this embodiment, by injecting a preset small-signal voltage disturbance into the AC side and simultaneously measuring key electrical quantities (phase voltage, phase current, DC side voltage), and combining the joint small-signal linearization modeling of the control system (modulation signal expression) and main circuit (circuit expression) of the energy storage device, the problem of accurate impedance modeling of energy storage devices with active control power electronic interfaces was successfully solved. Based on the above modeling, the decisive influence of control dynamics and DC coupling on impedance was accurately captured, ensuring the high fidelity of the model near the operating point, providing a direct basis for impedance reshaping control design, and ultimately significantly improving the reliability of the small-signal stability analysis results of the entire coupled system.

[0084] In an exemplary embodiment, the steps of constructing the impedance model of a heavy-haul train include: obtaining the modulation signal expression of a single-phase voltage converter in the heavy-haul train based on the AC voltage reference amplitude and the DC equivalent resistance of the heavy-haul train; obtaining the circuit expression of the heavy-haul train; and obtaining the impedance model of the heavy-haul train based on the modulation signal expression of the single-phase voltage converter in the heavy-haul train and the circuit expression of the heavy-haul train.

[0085] Among them, the DC-side equivalent resistance of heavy-haul trains can be used to reflect the equivalent dynamic resistance characteristics of the inverter and its driven motor load to the DC bus.

[0086] For example, the steps of the server constructing the impedance model of a heavy-haul train include: modeling the control loop of the single-phase voltage converter of the heavy-haul train. The control loop of the heavy-haul train consists of a DC voltage control loop and an AC current control loop. The function of the DC voltage control loop is to output a reference value for the AC side input current it, and its frequency domain expression is... The expression is as follows:

[0087]

[0088] in, This represents the reference value of the input current when the frequency is 0. This is the output voltage on the DC side. It is the transfer function of the voltage control loop. This is the reference amplitude of the AC side voltage. The equivalent resistance of a DC-side heavy-haul train varies depending on the tonnage of the heavy-haul train and whether it operates in series or parallel.

[0089] The single-phase voltage converter of the heavy-haul train adopts direct current control. Based on the AC current control loop diagram, the modulation signal of the single-phase voltage converter can be derived. The frequency domain expression is:

[0090]

[0091] in, The DC side voltage is given by νt, and the AC side phase voltage is given by νt. For AC side voltage control loop gain, The phase obtained by SOGI_PLL is Rt and Lt, which are the equivalent resistance and inductance of the train transformer, respectively.

[0092] Based on the modulation signal of the single-phase voltage converter The expression, and the circuit equation expression of the heavy-haul train derived from the circuit topology diagram of the heavy-haul train, are used to derive the expression of each impedance (impedance model of the heavy-haul train) by substituting the variables mentioned above into the equation expression in this embodiment, as shown in the following formula:

[0093]

[0094] Wherein, the subscript p represents the system response when a positive mirror frequency is injected, the subscript n represents the system response when a negative mirror frequency is injected, Zpp represents the positive sequence impedance of the single-phase voltage converter, Zpn and Znp represent the coupling impedance between their positive and negative sequences, and Znn represents the negative sequence impedance. , , , This is a complex frequency domain expression.

[0095] In this embodiment, by introducing the DC-side equivalent resistance characterizing the load dynamics and combining it with the joint small-signal modeling of the train rectifier control system (modulation signal expression) and the main circuit (circuit expression of heavy-load train), the problem of accurately modeling the input impedance of the core dynamic load of heavy-load train was successfully solved. The decisive influence of load power dynamics (especially negative resistance characteristics) and control dynamics on the input impedance was accurately captured, and an operating point correlation model that strictly matches the operation diagram state was established. Ultimately, it provides an indispensable key input and theoretical basis for accurately evaluating the impact of the train on the small-signal stability of the system, optimizing the operation diagram, and preventing low-frequency oscillations.

[0096] In an exemplary embodiment, after obtaining the impedance equivalent model of the coupled system, the method for small-signal stability analysis of the coupled system of heavy-haul railway further includes: constructing a simulation model of the coupled system; injecting a second preset small-signal voltage disturbance into the simulation model and performing simulation to obtain a measured impedance value; obtaining a theoretical impedance value based on the second preset small-signal voltage disturbance and the impedance equivalent model of the coupled system; verifying the impedance equivalent model based on the measured impedance value and the theoretical impedance value; and, if the verification result indicates that the impedance equivalent model is correct, performing a small-signal stability analysis of the coupled system based on the impedance equivalent model of the coupled system, according to a preset stability criterion, as well as the operation diagram, operation mode, and connection scheme.

[0097] The simulation model of the coupled system can refer to a complete simulation model built in professional electronic simulation software based on the aforementioned operating diagram, operating mode, connection scheme, and physical models of each component (traction transformer, traction network, energy storage device, and heavy-haul train). The second preset small-signal voltage disturbance can refer to a tiny voltage change with an amplitude much smaller than the normal operating voltage of the simulation model. Its purpose is not to change the main operating point of the simulation model, but only to stimulate its linear dynamic response under small disturbances. The measured impedance value can refer to the impedance value of the response after injecting the second preset small-signal voltage disturbance through simulation experiments. The theoretical impedance value can refer to the theoretical impedance value obtained by theoretical calculation based on the equivalent impedance model of the coupled system.

[0098] For example, the server can build a time-domain simulation model of the coupled system (simulation model of the coupled system) in MATLAB / Simulink, and combine two independent voltage disturbances. and (The second preset small-signal voltage disturbance) is injected into the time-domain simulation model in two parts to simulate impedance measurement. In this embodiment, the disturbance... and Represented as:

[0099]

[0100]

[0101] in, and These are the amplitudes of the first positive-sequence and negative-sequence interference voltages, respectively. and These represent the phases of the first positive-sequence and negative-sequence interference voltages, respectively. and These are the amplitudes of the second positive-sequence and negative-sequence interference voltages, respectively. and These represent the phases of the second positive-sequence and negative-sequence interference voltages, respectively. and These are the frequencies of the positive-sequence and negative-sequence interference voltages, respectively.

[0102] The response current on the AC side after the voltage disturbance is injected is as follows:

[0103]

[0104]

[0105] in, and These are the amplitudes of the first positive-sequence and negative-sequence interference currents, respectively. and These represent the phases of the first positive-sequence and negative-sequence interference currents, respectively. and These are the amplitudes of the second positive-sequence and negative-sequence interference currents, respectively. and These are the phases of the second positive-sequence and negative-sequence interference currents, respectively.

[0106] The measured impedance is expressed as follows:

[0107]

[0108] Where Zpp represents the positive sequence impedance, Zpn and Znp represent the coupling impedance between their positive and negative sequences, and Znn represents the negative sequence impedance.

[0109] Then, by comparing the measured impedance (measured impedance value) with the theoretically calculated impedance (theoretical impedance value), the correctness of the equivalent impedance model can be verified. Finally, if the equivalent impedance model is correct, the steps of performing small-signal stability analysis on the coupled system based on the impedance equivalent model of the coupled system, according to the preset stability criteria, as well as the operation diagram, operation mode and connection scheme, are executed.

[0110] In this embodiment, a simulation model is constructed and a small-signal voltage disturbance is injected to obtain the measured impedance. The measured impedance is then quantitatively compared and verified with the impedance equivalent model. The final stability analysis is only performed after the verification is passed. This adds a crucial "quality assurance" step to the entire small-signal stability analysis method for heavy-haul railways, greatly improving the credibility of the impedance equivalent model and the acceptability of the stability analysis conclusions.

[0111] In an exemplary embodiment, the coupling system of a heavy-haul railway includes: a traction substation, a traction grid, an autotransformer (AT) transformer, a single-phase AC / DC converter, a single-phase DC / DC converter, an energy storage device, a traction transformer, an AT substation, a sectioning station, and a heavy-haul train. Specifically: the traction substation is connected to the external power grid; the traction transformer is used to reduce the voltage of the external power grid to the traction voltage; the single-phase DC / DC converter and the single-phase AC / DC converter are directly connected to the traction grid; the control of the single-phase DC / DC converter and the single-phase AC / DC converter is used to realize energy transfer between the traction grid and the energy storage device; an AT transformer is installed at predetermined intervals along the heavy-haul railway track; the AT transformer is used to implement the AT power supply mode of the traction transformer; the wiring configuration of the traction transformer includes at least one of the V / X wiring scheme and the Scott wiring scheme; the AT substation and the sectioning station are connected via an autotransformer model.

[0112] In this context, AT transformer can refer to an autotransformer. AT institute can refer to an autotransformer institute or a functional facility built around an AT transformer.

[0113] This embodiment presents a physical construction model of the coupled system of a heavy-haul railway. Through the physical composition of the coupled system of the heavy-haul railway described above, a clear, complete and engineering-realistic object is provided for the subsequent small-signal stability analysis process and the modeling process therein, ensuring the physical integrity and authenticity of the model, and focusing on solving the stability problems unique to heavy-haul railways.

[0114] In one exemplary embodiment, such as Figure 3 As shown, this embodiment also provides a "source-grid-storage-train" coupling system for heavy-haul railways, comprising: a traction substation 11, a traction grid 12, an AT transformer 13, a single-phase AC / DC converter 14, a single-phase DC / DC converter 15, an energy storage device 16, and a heavy-haul train 20. The traction substation 11 is connected to an external 110kV power grid, and a three-phase traction transformer 17 is used to reduce the voltage to 25kV. An AT transformer 13 is installed every 20km along the track. The single-phase DC / DC converter 15 and AC / DC converter 14 are directly connected to the traction grid 12, and energy transfer between the traction grid 12 and the energy storage device 16 is achieved through converter control. The wiring configuration of the traction transformer 17, which uses AT power supply, mainly adopts V / X wiring and Scott wiring schemes. The connection between the AT substation 18 and the sectioning substation 19 adopts an autotransformer model. The A, B, and C lines in the external 110kV power grid represent three-phase lines respectively. In the traction network 12: T represents the overhead contact line, R represents the rail, and F represents the positive feeder.

[0115] Based on the aforementioned "source-grid-storage-car" coupled system of heavy-haul railways, this application also provides a method for small-signal stability analysis of the "source-grid-storage-car" coupled system of heavy-haul railways, including the following steps:

[0116] Step W1: Determine the timetable for the heavy-haul train 20, the operating mode of the traction network 12, and the connection scheme for the traction transformer 17.

[0117] Step W2: Construct impedance modeling for traction transformer 17, AT traction network 12, energy storage device 16, and heavy-haul train 20 in the "source-network-storage-train" coupled system of heavy-haul railway.

[0118] Step W3: Based on the operation diagram and impedance model of heavy-haul train 20, the "source-network-storage-vehicle" coupled system of heavy-haul railway is simplified by equivalent means.

[0119] Step W4: Build a simulation model of the "source-network-storage-vehicle" coupled system of heavy-haul railway, inject two independent small-signal voltage disturbances into the system, obtain the measured impedance value, compare it with the theoretical value, and verify the correctness of the model.

[0120] Step W5: Based on relevant stability criteria, analyze the stability of the "source-network-storage-vehicle" coupled system of heavy-haul railway under different operating conditions.

[0121] Specifically, in step W1 above, the timetable for the heavy-haul train 20 includes the train number, train timetable, route information, train type, train formation information, and speed requirements of the heavy-haul train 20; the train type includes freight trains, double-stack container trains, and bulk cargo trains, etc.; the train formation information includes the number of carriages and the tonnage; the traction network 12 has three main operating modes: full parallel operation, end parallel operation, and non-parallel operation; the connection scheme of the traction transformer 17 is mainly divided into two schemes: V / X connection and Scott connection.

[0122] Specifically, in step W2 above, the impedance modeling method for the traction transformer 17 is as follows: When the wiring method of the traction transformer is the V / X scheme (e.g. Figure 4 (a) V / X transformer connection shown). The number of turns in windings AC, TN, and NF are denoted as w1, w2, and w3, respectively, where w2 equals w3. The ratio of the primary side to the secondary side, w1 / w2, is denoted as k. Based on the principle of magnetomotive force balance, the corresponding equation can be expressed as follows:

[0123]

[0124] in, It is the primary side voltage normalized to the secondary side. , It is the voltage between TN and NF; , It represents the current in TN and NF. It is the short-circuit impedance between winding 1 and winding 2, normalized to one side of winding 2; It is the short-circuit impedance between winding 1 and winding 3, normalized to one side of winding 3. This is the equivalent leakage reactance of winding 1, normalized to one side of winding 2. Since windings 2 and 3 are symmetrically arranged and have the same number of turns, therefore... .

[0125] Based on the above formula, the relationship between the primary and secondary load currents can be derived as follows:

[0126]

[0127] The voltage equation at the secondary side of the transformer can be written as:

[0128]

[0129] From the above formula, it can be seen that the V / X traction transformer can be used with impedance Z2 and Z3 represent the equivalent circuit as follows: Figure 4 The equivalent circuit diagram shown in (b) is as follows.

[0130]

[0131] When the traction transformer is connected in the Scott scheme (e.g.) Figure 5 The equivalent circuit diagram of (a) Scott transformer connection shown is as follows: Figure 5 The equivalent circuit diagram shown in (b), taking only phase β with a negative load as an example, can be represented by the following equations:

[0132]

[0133] in, It is the leakage impedance of the primary winding AD of the T-type transformer. It is the leakage impedance of the secondary winding ad of the T-type transformer. It is the mutual impedance between the primary winding AD and the secondary winding ad of a T-type transformer. , It is the leakage impedance of the primary windings CD and DB of the M-type transformer. Due to the symmetrical structure, there is... , It is the mutual impedance between the two primary windings CD and DB of the M-type transformer. It is the leakage impedance of the secondary winding bc of the M-type transformer. , It is the mutual impedance between the secondary winding bc and the primary windings CD and DB of the transformer. , , It is the induced electromotive force corresponding to the primary magnetic flux in windings BC and bc, and K is the turns ratio w1 / w2 of windings w1 and w2.

[0134] Based on the above formula, the corresponding equation can be written as:

[0135]

[0136] in, It is the β-phase no-load voltage.

[0137]

[0138] The equivalent impedance of the traction transformer can be derived as follows:

[0139]

[0140] Similarly, when only phase α is loaded, The expression can be written as:

[0141]

[0142] The impedance modeling method for traction network 12 is as follows: For traction network 12 operating in full parallel, the impedances of lines T, R, and F are respectively... , and The mutual impedances between lines T, R, and F are respectively , and The length of the AT section where the locomotive is located is D, and the distance from the locomotive's short-circuit point to the previous AT section is x. Let x represent the current at point x, and let x represent the traction current of the locomotive. When a short circuit occurs in the upstream section of the overhead contact line, the contact line current can be analyzed using the generalized connection method of the nearby locomotive and traction substation 11. Track current Upward positive feeder current and down-track current This allows for the determination of the current in the downlink contact network and the positive feeder. During normal operation of the fully parallel traction network 12, three closed circuits are established between the uplink and downlink contact networks, the positive feeder, and the track. The voltage drop equations for these three circuits are as follows:

[0143]

[0144] The current of the traction network operating in full parallel can be written in the following form:

[0145]

[0146] Based on the above formula, the impedance of the traction network in the fully parallel operation mode can be calculated, as shown in the following expression:

[0147]

[0148]

[0149]

[0150] The length of the power supply arm is l.

[0151] For impedance calculation formulas under other traction network 12 operating modes, please refer to the previous analysis.

[0152] The impedance modeling method for energy storage device 16 is as follows: First, a small-signal voltage disturbance is injected into the AC side. When a disturbance voltage with a frequency of fp+f1 is injected into the system, the corresponding signal frequency is fp-f1. The signal with a frequency of fp+f1 is called the "positive mirror frequency" signal, and the signal with a frequency of fp-f1 is called the "negative mirror frequency" signal. In this invention, the small-signal voltage disturbance injected into the AC side is:

[0153]

[0154]

[0155] in, and The amplitude and phase of the voltage disturbance corresponding to the positive mirror frequency are given; the above small-signal voltage disturbances include both incremental and decremental disturbances.

[0156] Next, calculate the phase voltage. Current and DC side voltage Their expressions are as follows:

[0157]

[0158]

[0159]

[0160] in, and The amplitude and phase of the fundamental voltage at frequency f1; and The definition of current follows the same rules as for the amplitude and phase of voltage disturbances at the corresponding positive mirror frequency. Indicates the DC voltage amplitude. and This represents the voltage amplitude and phase corresponding to the disturbance frequency fp.

[0161] In this embodiment, SOGI_PLL is used to track phase voltage. The phase can also be tracked using other methods to obtain... and From the frequency domain expression, the output of the DC bus voltage control loop is obtained. The expression is used to derive the modulation signal of the single-phase voltage converter. The expression describes the dq-domain indirect current control method used in the single-phase voltage converter of the energy storage device 16. This requires transforming the voltage and current in phases α and β to the dq coordinate system. The control loop of the single-phase voltage converter consists of a voltage control loop and a current control loop. A proportional-integral controller is used for voltage control to ensure a constant DC bus voltage. The modulation signal of the single-phase voltage converter is also described. The expression is as follows:

[0162]

[0163] in, , For the output variable of the current control loop, symbol This represents convolution.

[0164] Finally, based on the circuit topology diagram of energy storage device 16, the circuit equation expression is derived. Substituting the quantities into the equation expression, the expression for each impedance is derived as follows:

[0165]

[0166] Wherein, the subscript p represents the system response when the positive mirror frequency is injected, the subscript n represents the system response when the negative mirror frequency is injected, Zpp represents the positive sequence impedance of the energy storage device, Zpn and Znp represent the coupling impedance between their positive and negative sequences, and Znn represents the negative sequence impedance. , , , This is a complex frequency domain expression.

[0167] like Figure 6 The diagram shown is a schematic diagram and control strategy block diagram of an energy storage device 16 in a "source-grid-storage-vehicle" coupled system for heavy-haul railways according to this application. The energy storage device 16 mainly consists of an equivalent capacitor and a resistor connected in parallel, and is connected to the traction network 12 through a single-phase voltage converter. The equivalent capacitor is denoted as C. eq ;R m L m These are the equivalent resistance and inductance of the matching transformer (used to reduce the voltage level, lowering the 27.4kV voltage on the traction network to a voltage level suitable for energy storage devices); the AC phase voltage is denoted as v. s The phase current is denoted as i s ;v ds This refers to the output voltage. The phase obtained by SOGI_PLL; m s The current control loop outputs a modulation signal.

[0168] The impedance modeling method for the heavy-haul train 20 is as follows: The signal usage of SOGI_PLL is the same as that of the energy storage device 16 mentioned above, and will not be repeated here. Then, the control loop of the single-phase voltage converter of the heavy-haul train 20 is modeled. The control loop of the heavy-haul train 20 (10) consists of a DC voltage control loop and an AC current control loop. The function of the DC voltage control loop is to output the reference value of the AC side input current it. Its frequency domain expression is... The expression is as follows:

[0169]

[0170] in, This represents the reference value of the input current when the frequency is 0. This is the output voltage on the DC side. It is the transfer function of the voltage control loop. This is the reference amplitude of the AC side voltage. The equivalent resistance of the DC-side heavy-haul train 20 will vary depending on the tonnage of the heavy-haul train 20 and its series-parallel operation.

[0171] Unlike the single-phase voltage converter control strategy of energy storage device 16, the single-phase voltage converter of heavy-haul train 20 adopts direct current control. Based on the AC current control loop diagram, the modulation signal of the single-phase voltage converter can be derived. The frequency domain expression is:

[0172]

[0173] in, The DC side voltage is V, and the AC side phase voltage is v. t , For AC side voltage control loop gain, For the phase obtained by SOGI_PLL, R t L t These are the equivalent resistance and inductance of the train transformer, respectively.

[0174] Based on the modulation signal of the single-phase voltage converter Based on the method for solving the impedances of the energy storage device 16, the expressions for the impedances of the single-phase voltage converter of the heavy-haul train 20 can be obtained as follows:

[0175]

[0176] Wherein, the subscript p represents the system response when a positive mirror frequency is injected, the subscript n represents the system response when a negative mirror frequency is injected, Zpp represents the positive sequence impedance of the single-phase voltage converter, Zpn and Znp represent the coupling impedance between their positive and negative sequences, and Znn represents the negative sequence impedance. , , , This is a complex frequency domain expression.

[0177] like Figure 7 The diagram shown illustrates the topology and control strategy of a heavy-haul train 20 within a "source-grid-storage-vehicle" coupled system for heavy-haul railways, as described in this application. It primarily consists of a single-phase voltage converter, with a DC-side load of R. d C d The capacitor is on the DC side, and the phase voltage on the AC side is v. t The phase current is i t v dt The DC-side output voltage, m t To control the output modulation signal of the loop.

[0178] Specifically, in step W4 above, a time-domain simulation model of the "source-grid-storage-vehicle" coupled system is built in MATLAB / Simulink, and the two independent voltage disturbances are considered. and The system is injected in two parts, and impedance measurement is simulated. The perturbation of this invention... and Represented as:

[0179]

[0180]

[0181] in, and These are the amplitudes of the first positive-sequence and negative-sequence interference voltages, respectively. and These represent the phases of the first positive-sequence and negative-sequence interference voltages, respectively. and These are the amplitudes of the second positive-sequence and negative-sequence interference voltages, respectively. and These represent the phases of the second positive-sequence and negative-sequence interference voltages, respectively. and These are the frequencies of the positive-sequence and negative-sequence interference voltages, respectively.

[0182] The response current on the AC side is expressed as follows:

[0183]

[0184]

[0185] in, and These are the amplitudes of the first positive-sequence and negative-sequence interference currents, respectively. and These represent the phases of the first positive-sequence and negative-sequence interference currents, respectively. and These are the amplitudes of the second positive-sequence and negative-sequence interference currents, respectively. and These are the phases of the second positive-sequence and negative-sequence interference currents, respectively.

[0186] The measured impedance is expressed as follows:

[0187]

[0188] Where Zpp represents the positive sequence impedance, Zpn and Znp represent the coupling impedance between their positive and negative sequences, and Znn represents the negative sequence impedance.

[0189] Then, the measured impedance is compared with the theoretically calculated impedance to verify the correctness of the model. The impedance simulation results and theoretical derivation results for the heavy-haul train 20 are as follows: Figure 8 As shown, the impedance simulation results and derivation results of energy storage device 16 are as follows: Figure 9 As shown, the black dots represent the impedance measured in the simulation model, and the red line represents the impedance derived from the model. It can be seen that for the heavy-haul train 20, the model impedance and the measured results are in high agreement. For the energy storage device 16, the model impedance and the measured impedance do not fit as well as the heavy-haul train 20 because their impedance amplitude is too small, which easily leads to larger measurement errors, but the deviation is still within 10dB.

[0190] Specifically, in step W5 above, the stability study of the "source-network-storage-vehicle" coupling system of heavy-haul railway mainly includes different numbers and control parameters of energy storage devices 16 and heavy-haul trains 20, different wiring methods of traction transformers 17, and different operating modes of AT traction network 12.

[0191] Among them, the number N of energy storage devices 16 connected is E There are 1 or 2 units; the load capacity of a heavy-haul train is 20 L. H There are 10,000 tons, 20,000 tons, and 30,000 tons. First, take N. E For example, the loads of 20 heavy-haul trains connected to the AT traction network 12 are set to 10,000, 20,000, and 30,000 tons respectively. The system Nyquist diagram is shown below. Figure 10 As shown in the figure, it can be seen that as the number of heavy-haul trains 20 increases, the system stability margin gradually decreases, but the system can always remain stable.

[0192] The control parameters of the energy storage device 16 mainly include the DC side voltage control loop proportional-integral gain. and DC-side current control loop proportional-integral gain and The control parameters for the heavy-haul train 20 include the DC-side voltage control loop proportional-integral gain. and AC side voltage control loop gain Energy storage device 16 It can take values ​​of 0.5, 0.7, and 0.9; It can take the values ​​5, 7, and 9; It can take the values ​​6, 8, and 10; The values ​​can be 100, 110, or 120. (This refers to a type of heavy-haul train, likely part of a larger train series.) It can take values ​​of 1, 1.2, and 1.4; It can take values ​​of 0.5, 0.7, and 0.9; It can take the values ​​5, 6, and 7.

[0193] The traction transformer 17 has two wiring schemes: V / X connection and Scott connection; the traction network 12 has two operating modes: full parallel operation, end parallel operation and non-parallel operation. Figure 11 Nyquist plots for different operating conditions are presented, where solid lines represent V / x transformer connection types and dashed lines represent Scott transformer connection types. Comparing the Nyquist curves under different colors shows that, for the same transformer connection type, fully parallel traction power supply has the best stability, followed by end-parallel connection, and non-parallel connection has the worst stability. Comparing solid and dashed lines shows that, for the same traction network power supply, the Scott traction transformer connection type has better system stability than the V / x traction transformer connection type. Furthermore, from... Figure 11 It can also be seen that the power supply method of the traction network has a greater impact on system stability than the wiring configuration of the traction transformer. In summary, from the perspective of system stability, in the actual design of the traction power supply system, the fully parallel traction power supply method with the Scoot traction transformer wiring configuration should be given priority.

[0194] This application establishes an impedance model for a heavy-haul railway "source-grid-storage-vehicle" coupled system, including impedance models of traction transformer 17, AT traction network 12, energy storage device 16, and heavy-haul train 20. This model can simplify the heavy-haul railway "source-grid-storage-vehicle" coupled system, improve the modeling efficiency of the heavy-haul railway "source-grid-storage-vehicle" coupled system, and help to further conduct stability analysis.

[0195] This application also proposes a small-signal stability analysis method for a heavy-haul railway "source-grid-storage-vehicle" coupled system. This method, combined with relevant stability criteria, can not only evaluate the overall stability of the heavy-haul railway "source-grid-storage-vehicle" coupled system under different operating conditions, but also analyze the influence mechanism of different control parameters and interactions on system stability, and provide the optimal stable operation mode of the heavy-haul railway "source-grid-storage-vehicle" coupled system, providing engineering design suggestions for practical applications.

[0196] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps. It is understood that the steps in different embodiments can be freely combined as needed, and all non-contradictory solutions formed by such combinations are within the scope of protection of this application.

[0197] Based on the same inventive concept, this application also provides a device for implementing the above-described method for analyzing the small-signal stability of a heavy-haul railway coupled system. The solution provided by this device is similar to the implementation described in the above method. Therefore, the specific limitations in one or more embodiments of the device for analyzing the small-signal stability of a heavy-haul railway coupled system provided below can be found in the limitations of the method for analyzing the small-signal stability of a heavy-haul railway coupled system described above, and will not be repeated here.

[0198] In one exemplary embodiment, such as Figure 12 As shown, a small-signal stability analysis device 900 for a heavy-haul railway coupling system is provided, comprising: an acquisition module 901, a construction module 902, a simplification module 903, and an analysis module 904, wherein:

[0199] The acquisition module 901 is used to acquire the operation diagram of heavy-haul trains in the coupling system of heavy-haul railway, the operation mode of the traction network in heavy-haul railway, and the connection scheme of traction transformers.

[0200] Module 902 is used to construct impedance models for the traction transformer, traction network, energy storage device and heavy-haul train in the coupled system, respectively.

[0201] The simplification module 903 is used to simplify the coupled system based on the operation diagram and the impedance models of the traction transformer, traction network, energy storage device and heavy-haul train in the coupled system, and obtain the impedance equivalent model of the coupled system.

[0202] Analysis module 904 is used to perform small-signal stability analysis on the coupled system based on the impedance equivalent model of the coupled system, according to preset stability criteria, as well as the operation diagram, operation mode and connection scheme.

[0203] In an exemplary embodiment, the traction network operates in a fully parallel mode. The aforementioned construction module 902 is further configured to, when the traction network is operating in full parallel, analyze the contact network current, track current, uplink positive feeder current, and downlink track current using a generalized connection method involving adjacent locomotives and traction substations to determine the downlink contact network current and positive feeder current; obtain the voltage drop expressions corresponding to the three closed circuits between the uplink and downlink contact networks, positive feeders, and tracks; and obtain the impedance model of the traction network based on the downlink contact network current, positive feeder current, and voltage drop expressions.

[0204] In an exemplary embodiment, the aforementioned construction module 902 is further configured to inject a first preset small-signal voltage disturbance into the AC side of the energy storage device to obtain the phase voltage, phase current, and DC side voltage; obtain the modulation signal expression of the single-phase voltage converter in the energy storage device based on the phase voltage, phase current, and DC side voltage; obtain the circuit expression of the energy storage device; and obtain the impedance model of the energy storage device based on the modulation signal expression of the single-phase voltage converter in the energy storage device and the circuit expression of the energy storage device.

[0205] In an exemplary embodiment, the above-mentioned construction module 902 is further configured to obtain the modulation signal expression of the single-phase voltage converter in the heavy-load train based on the AC voltage reference amplitude and the DC equivalent resistance of the heavy-load train; obtain the circuit expression of the heavy-load train; and obtain the impedance model of the heavy-load train based on the modulation signal expression of the single-phase voltage converter in the heavy-load train and the circuit expression of the heavy-load train.

[0206] In an exemplary embodiment, the above-mentioned small-signal stability analysis device for a heavy-haul railway coupling system further includes a verification module, which is used to construct a simulation model of the coupling system, inject a second preset small-signal voltage disturbance into the simulation model and perform simulation to obtain a measured impedance value; obtain a theoretical impedance value based on the second preset small-signal voltage disturbance and the impedance equivalent model of the coupling system; verify the impedance equivalent model based on the measured impedance value and the theoretical impedance value; and, if the verification result indicates that the impedance equivalent model is correct, perform a small-signal stability analysis of the coupling system based on the impedance equivalent model of the coupling system, according to a preset stability criterion, as well as the operation diagram, operation mode and connection scheme.

[0207] Each module in the aforementioned small-signal stability analysis device 900 for heavy-haul railway coupling systems can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0208] In one exemplary embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 13 As shown, this computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and databases. The internal memory provides the environment for the operating system and computer programs stored in the non-volatile storage media. The I / O interfaces are used for exchanging information between the processor and external devices. The communication interface is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements a small-signal stability analysis method for a heavy-haul railway coupled system.

[0209] Those skilled in the art will understand that Figure 13 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0210] In one embodiment, a computer device is also provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above method embodiments.

[0211] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon that, when executed by a processor, implements the steps in the above method embodiments.

[0212] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0213] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0214] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0215] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for small-signal stability analysis of a heavy-haul railway coupling system, characterized in that, The method includes: To obtain the train operation diagram of heavy-haul railway in the coupling system, the operation mode of the traction network in heavy-haul railway, and the connection scheme of traction transformer; Impedance models of the traction transformer, traction network, energy storage device, and heavy-haul train in the coupling system are constructed respectively. Based on the operation diagram and the impedance models of the traction transformer, traction network, energy storage device and heavy-haul train in the coupling system, the coupling system is simplified by equivalent means to obtain the impedance equivalent model of the coupling system. Based on the impedance equivalent model of the coupled system, and according to the preset stability criteria, as well as the operation diagram, the operation mode, and the connection scheme, a small-signal stability analysis is performed on the coupled system.

2. The method according to claim 1, characterized in that, The traction network operates in a fully parallel mode; The steps for constructing the impedance model of the traction network include: When the traction network is in full parallel operation, the contact network current, track current, up line positive feeder current and down line track current are analyzed by the generalized connection method of adjacent locomotives and traction substations to determine the down line contact network current and positive feeder current. Obtain the voltage drop expressions for the three closed circuits between the uplink and downlink overhead contact lines, the positive feeder, and the track; The impedance model of the traction network is obtained based on the current of the downlink contact network, the current of the positive feeder, and the voltage drop expression.

3. The method according to claim 1, characterized in that, The steps for constructing the impedance model of the energy storage device include: A first preset small signal voltage disturbance is injected into the AC side of the energy storage device to obtain the phase voltage, phase current and DC side voltage; Based on the phase voltage, the phase current, and the DC-side voltage, obtain the modulation signal expression of the single-phase voltage converter in the energy storage device; Obtain the circuit expression of the energy storage device, and based on the modulation signal expression of the single-phase voltage converter in the energy storage device and the circuit expression of the energy storage device, obtain the impedance model of the energy storage device.

4. The method according to claim 1, characterized in that, The steps for constructing the impedance model of the heavy-haul train include: Based on the AC voltage reference amplitude and the DC equivalent resistance of the heavy-haul train, the modulation signal expression of the single-phase voltage converter in the heavy-haul train is obtained. Obtain the circuit expression of the heavy-haul train, and based on the modulation signal expression of the single-phase voltage converter in the heavy-haul train and the circuit expression of the heavy-haul train, obtain the impedance model of the heavy-haul train.

5. The method according to claim 1, characterized in that, After obtaining the impedance equivalent model of the coupled system, the method further includes: A simulation model of the coupling system is constructed, a second preset small-signal voltage disturbance is injected into the simulation model and simulation is performed to obtain the measured impedance value. The theoretical impedance value is obtained based on the second preset small-signal voltage disturbance and the impedance equivalent model of the coupling system; The impedance equivalent model is verified based on the measured impedance value and the theoretical impedance value. If the verification result indicates that the impedance equivalent model is correct, the following steps are performed: based on the impedance equivalent model of the coupled system, and according to the preset stability criteria, the operation diagram, the operation mode, and the connection scheme, small-signal stability analysis is performed on the coupled system.

6. The method according to any one of claims 1 to 4, characterized in that, The coupling system includes: traction substation, traction network, AT transformer, single-phase AC / DC converter, single-phase DC / DC converter, energy storage device, traction transformer, AT substation, sectioning station, and heavy-haul train, wherein: The traction substation is connected to the external power grid, and the traction transformer is used to reduce the voltage of the external power grid to the traction voltage; The single-phase DC / DC converter and the single-phase AC / DC converter are directly connected to the traction network, and the control of the single-phase DC / DC converter and the single-phase AC / DC converter is used to realize the energy transfer between the traction network and the energy storage device. An AT transformer is installed at preset intervals along the heavy-haul railway track. The AT transformer is used to realize the AT power supply mode of the traction transformer. The wiring configuration of the traction transformer includes at least one of the V / X wiring scheme and the Scott wiring scheme; The AT station and the partition station are connected via an autotransformer model.

7. A small-signal stability analysis device for a heavy-haul railway coupling system, characterized in that, The device includes: The acquisition module is used to acquire the train operation diagram of heavy-haul trains in the coupling system of heavy-haul railway, the operation mode of the traction network in heavy-haul railway, and the connection scheme of traction transformers. The construction module is used to construct the impedance models of the traction transformer, traction network, energy storage device and heavy-haul train in the coupled system, respectively. The simplification module is used to perform equivalent simplification of the coupled system based on the operation diagram and the impedance models of the traction transformer, traction network, energy storage device and heavy-haul train in the coupled system, so as to obtain the impedance equivalent model of the coupled system. The analysis module is used to perform small-signal stability analysis on the coupled system based on the impedance equivalent model of the coupled system, according to the preset stability criteria, as well as the operation diagram, the operation mode and the connection scheme.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

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