Modeling method of urban rail transit locomotive considering dc network voltage and mechanical speed

Abstract

The present application relates to the technical field of locomotive modeling, in particular to a kind of urban rail transit locomotive modeling method considering direct current network voltage and mechanical rotating speed, comprising: constructing initial locomotive model of target locomotive traction system including control system model, three-phase alternating current asynchronous motor dynamic model and frequency converter dynamic model;Constructing AC-DC side instantaneous power equivalent model to replace the rotor flux linkage tracking dynamic process of initial locomotive model, to realize the accurate description of motor transient starting stage at motor frequency converter direct current port, further ignore the current inner loop dynamic process of initial locomotive model, to retain the rotating speed outer loop control model and active damping feedforward control model of initial locomotive model, obtain the locomotive model considering the influence of direct current network voltage and mechanical rotating speed. Therefore, the defects that traditional detailed dynamic model is difficult to carry out mechanism analysis and simulation efficiency is low, and the problems such as the deficiency that commonly used current equivalent power source model cannot reflect the transient mechanism of large disturbance are solved.

Description

Technical Field

[0001] This invention relates to the field of locomotive modeling technology, and in particular to a method for modeling urban rail transit locomotives that considers DC grid voltage and mechanical speed. Background Technology

[0002] The traction power supply system for urban rail transit is crucial for its safe and efficient operation. Traditional traction power supply systems convert medium- and high-voltage AC power into DC power using diode rectifier units to provide power to the locomotives. In recent years, flexible DC traction power supply systems based on bidirectional converters have become the next-generation high-reliability, green power supply direction for urban rail transit due to their ability to flexibly control voltage, improve regenerative energy utilization, and enhance system power supply capacity and reliability. This system is a 100% power electronic system, with bidirectional converter clusters and locomotive clusters widely and deeply coupled on a long-chain contact network. The dynamic interaction is complex, and the system is large-scale, placing higher demands on the accuracy and efficiency of the locomotive model. Urban rail transit locomotives use a DC power supply system, such as... Figure 1 As shown, the locomotive's pantograph draws power from the DC traction network. Therefore, for urban rail transit, the dynamic model of the locomotive traction system describes the response of the locomotive current IDC when the DC voltage UDC of the traction network changes. However, the locomotive actually uses a three-phase AC asynchronous motor, which is controlled by a DC / AC converter and its control system using variable voltage variable frequency (VVVF).

[0003] In traditional traction power supply system analysis, locomotives are often simply modeled as constant power loads, and their negative damping characteristics are overemphasized. When combined with a bidirectional converter, this easily leads to a significant overestimation of the system's required damping, resulting in misjudgments of system operating capacity and wasted equipment costs. For example, ... Figure 2 As shown, related technologies have proposed a constant power modeling method for urban rail transit locomotives that considers voltage control. This scheme takes into account the inductance and capacitance on the DC side of the locomotive, ignores the dynamic characteristics of the AC motor, and assumes that the motor power is a constant value, which is reflected on the DC side of the frequency converter after lossless transformation. Therefore, the design of flexible DC traction power supply systems urgently requires a more accurate locomotive dynamic model.

[0004] Furthermore, traditional traction power supply systems typically only consider the generator sets and locomotives within a single power supply section. In contrast, flexible DC traction power supply systems require global coordinated control among multiple bidirectional converters. These bidirectional converters are directly electrically coupled to multiple locomotives via the overhead contact line. Dynamic performance analysis of the system necessitates considering the combined effects of the source-grid-vehicle system across the entire line, significantly increasing the computational scale of the flexible DC system simulation. However, the complex structure of detailed electromagnetic transient models of locomotives leads to lengthy simulation times and inconvenient applications, making them unsuitable for simulating multiple systems and numerous operating conditions in practical engineering. Simultaneously, the overly complex electromagnetic transient models of locomotives also hinder research into the stability mechanisms of the power supply system. Summary of the Invention

[0005] This invention provides a modeling method for urban rail transit locomotives that considers DC grid voltage and mechanical speed, in order to solve the problems of traditional detailed dynamic models being difficult to perform mechanism analysis and having low simulation efficiency, as well as the inadequacy of commonly used equivalent power source models in reflecting large disturbance transient mechanisms.

[0006] A first aspect of the present invention provides a method for modeling urban rail transit locomotives that considers DC grid voltage and mechanical rotation speed, comprising the following steps: Construct an initial locomotive model for the target locomotive traction system; An equivalent power model for the AC / DC side is constructed to replace the rotor flux tracking dynamic process of the initial locomotive model, thereby achieving an accurate description of the transient initial stage of the motor at the DC port of the motor inverter. Furthermore, the current inner loop dynamic process of the initial locomotive model is ignored, while retaining the speed outer loop control model and the active damping feedforward control model of the initial locomotive model, resulting in a locomotive model that considers the influence of DC grid voltage and mechanical speed.

[0007] Optionally, the initial locomotive model for constructing the target locomotive traction system includes: In the synchronous rotation coordinate system of the rotor flux linkage, a dynamic model of the three-phase AC asynchronous motor of the target locomotive traction system is constructed; The dynamic model of the three-phase AC asynchronous motor is subjected to rotor flux orientation vector control to obtain the control system model; According to the instructions output of the control system model, the DC voltage is output as the three-phase AC motor stator input voltage through space vector modulation, so as to construct the frequency converter dynamic model based on the three-phase AC motor stator input voltage; The initial locomotive model is generated based on the control system model, the three-phase AC asynchronous motor dynamic model, and the frequency converter dynamic model.

[0008] Optionally, the construction of an AC / DC side instantaneous power equivalent model to replace the rotor flux tracking dynamic process of the initial locomotive model achieves an accurate description of the transient initial stage of the motor at the DC port of the motor inverter. Furthermore, the current inner loop dynamic process of the initial locomotive model is ignored, while retaining the speed outer loop control model and active damping feedforward control model of the initial locomotive model, resulting in a locomotive model considering the influence of DC grid voltage and mechanical speed, including: The current inner loop feedforward of the initial locomotive model is combined, and the overall transfer function of the current inner loop is used to replace the path gain from the current setpoint to the actual current value to obtain the initial locomotive traction system model. An equivalent power model for the AC / DC side is constructed to replace the flux delay element in the open-loop control of the flux linkage in the initial locomotive traction system model, so as to accurately describe the transient start-up stage of the motor at the DC port of the motor inverter. Furthermore, the dynamic process of the inner current loop of the initial locomotive traction system model is ignored, so as to retain the outer speed control model and the active damping feedforward control model of the initial locomotive traction system model, thus obtaining the locomotive model considering the influence of DC grid voltage and mechanical speed.

[0009] Optionally, the locomotive model considering the influence of DC grid voltage and mechanical speed includes a speed outer loop controller module, an active damping feedforward module, and a power equivalent module, wherein, The outer loop speed controller module is used to respond to the input mechanical speed input signal; The active damping feedforward module is used to respond to the input DC grid voltage signal; The power equivalent module is used to correct the AC / DC power relationship to output the locomotive DC current response signal.

[0010] Optionally, the specific expression for the locomotive model considering the influence of DC grid voltage and mechanical speed is as follows:

[0011] In the formula, This refers to the DC-side current of the frequency converter. For electromagnetic torque, For mechanical torque, For rotational inertia, This refers to the DC-side capacitor voltage of the frequency converter. Let the rotational speed be the outer loop transfer function. For complex frequency domain variables, For a given rotational speed, For mechanical rotation speed, For active damping feedforward coefficients, The active damped feedforward time constant is For a given magnetic flux, This is the rated voltage. For extreme logarithms, For mutual inductance between stator and rotor, This is the rotor's self-inductance.

[0012] Optionally, it also includes: Under the small disturbance condition that the change in DC grid voltage of the target locomotive traction system is less than 10% of the rated value, the locomotive model considering the influence of DC grid voltage and mechanical speed is simplified to include a constant power source with a current rise rate limit, a DC-side passive capacitor connected in parallel with the constant power source, and an active damping compensation module connected in parallel with the constant power source, wherein the current rise rate limit value is determined based on the bandwidth of the outer speed loop.

[0013] A second aspect of the present invention provides a modeling device for urban rail transit locomotives that considers DC grid voltage and mechanical rotation speed, comprising: The first model construction module is used to construct the initial locomotive model of the target locomotive traction system; The second model construction module is used to construct an equivalent power model for the AC / DC side instantaneous power to replace the rotor flux tracking dynamic process of the initial locomotive model. This enables an accurate description of the transient initial stage of the motor at the DC port of the motor inverter. Furthermore, the current inner loop dynamic process of the initial locomotive model is ignored, while retaining the speed outer loop control model and the active damping feedforward control model of the initial locomotive model, resulting in a locomotive model that considers the influence of DC grid voltage and mechanical speed.

[0014] A third aspect of the present invention provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the urban rail transit locomotive modeling method considering DC grid voltage and mechanical speed as described in the above embodiments.

[0015] A fourth aspect of the present invention provides a computer program product that, when executed by a processor, implements the above-mentioned urban rail transit locomotive modeling method considering DC grid voltage and mechanical speed.

[0016] A fifth aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described urban rail transit locomotive modeling method considering DC grid voltage and mechanical rotation speed.

[0017] The urban rail transit locomotive modeling method proposed in this invention, which considers DC grid voltage and mechanical speed, ignores the inner current loop regulation and flux tracking process in the locomotive traction system, while retaining the outer speed loop and active damping feedforward. This model reduces model complexity and achieves an accurate description of the locomotive's transient response when DC grid voltage drops. It overcomes the shortcomings of traditional detailed dynamic models, which are difficult to perform mechanism analysis and have low simulation efficiency. It also makes up for the inability of commonly used equivalent power source models to reflect the transient mechanism of large disturbances. This provides an efficient and accurate modeling tool for electromagnetic transient simulation of traction power supply systems under large disturbance conditions. Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the basic structure of a locomotive traction system; Figure 2 A schematic diagram of the existing constant power model for urban rail transit locomotives that considers voltage control; Figure 3 A flowchart illustrating a method for modeling urban rail transit locomotives that considers DC grid voltage and mechanical speed, provided in an embodiment of the present invention; Figure 4 This is a block diagram of a dynamic model of a three-phase AC asynchronous motor provided in an embodiment of the present invention; Figure 5 A block diagram of a control system model with active damping vector control provided for an embodiment of the present invention; Figure 6 This is a block diagram of a dynamic model of a frequency converter provided in an embodiment of the present invention; Figure 7 A detailed electromagnetic transient model block diagram of a locomotive provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of the inner and outer rings of a locomotive traction system provided in an embodiment of the present invention; Figure 9 This is a schematic diagram of the closed-loop amplitude-frequency logarithmic curves of the outer rotation speed loop and the inner current loop provided in an embodiment of the present invention. Figure 10 A block diagram of a locomotive model considering the influence of DC grid voltage and mechanical rotation speed is provided in an embodiment of the present invention; Figure 11 This is a block diagram of an equivalent locomotive model under low-disturbance operating conditions provided in an embodiment of the present invention; Figure 12A block diagram of an improved constant power source model for a locomotive under small disturbances, provided in an embodiment of the present invention; Figure 13 A block diagram of an urban rail transit locomotive modeling device considering DC grid voltage and mechanical speed, provided in an embodiment of the present invention; Figure 14 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention.

[0019] Explanation of reference numerals in the attached figures: 130-Urban rail transit locomotive modeling device considering DC grid voltage and mechanical speed, 1301-First model building module, 1302-Second model building module, 1401-Memory, 1402-Processor and 1403-Communication interface. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0021] The following describes, with reference to the accompanying drawings, an urban rail transit locomotive modeling method considering DC grid voltage and mechanical speed according to an embodiment of the present invention. Regarding the aforementioned background technology, in the analysis of traditional traction power supply systems, locomotives are often simply modeled as constant power loads, and their negative damping characteristics are excessively amplified. When combined with a bidirectional converter to form a system, the estimation of the system's required damping is easily exaggerated, leading to misjudgment of system operating capacity and waste of equipment costs. Furthermore, traditional traction power supply systems typically only need to consider the generator sets and locomotives within a single power supply section. However, in flexible DC traction power supply systems, multiple bidirectional converters require global coordinated control, and the bidirectional converters and multiple locomotives are directly electrically coupled through the overhead contact line. When analyzing the dynamic performance of the system, the combined influence of the source, grid, and vehicle on the entire line must be considered, significantly increasing the simulation calculation scale of the flexible DC system. Therefore, the locomotive dynamic model not only needs high accuracy but also needs to meet the requirements of efficient calculation. The complex structure of existing detailed electromagnetic transient models of locomotives leads to long simulation times and inconvenient application. This invention provides a modeling method for urban rail transit locomotives that considers DC grid voltage and mechanical speed. In this method, by establishing a detailed electromagnetic transient model of the target locomotive traction system, it can be seen that the electromagnetic dynamic characteristics and mechanical dynamic characteristics of the locomotive traction system are closely coupled. Thus, the current inner loop regulation and flux tracking process in the locomotive traction system are ignored, while the speed outer loop and active damping feedforward are retained, resulting in a locomotive model that considers the influence of DC grid voltage and mechanical speed. This addresses several issues: Firstly, the negative damping characteristics of a locomotive, simply modeled as a constant power load, are excessively amplified, leading to a significant overestimation of the required damping when combined with a bidirectional converter. Secondly, the complex structure of the locomotive's detailed electromagnetic transient model results in lengthy simulations and inconvenient applications, making it unsuitable for simulating multiple systems and numerous operating conditions in practical engineering. Furthermore, the excessive complexity of the locomotive's electromagnetic transient model hinders research into the stability mechanisms of power supply systems.

[0022] Specifically, Figure 3 This is a flowchart illustrating a method for modeling urban rail transit locomotives that considers DC grid voltage and mechanical speed, provided in an embodiment of the present invention.

[0023] like Figure 3 As shown, the urban rail transit locomotive modeling method considering DC grid voltage and mechanical speed includes the following steps: In step S301, an initial locomotive model of the target locomotive traction system is constructed.

[0024] In some embodiments, constructing an initial locomotive model for the target locomotive traction system includes: In the synchronous rotating coordinate system of the rotor flux linkage, a dynamic model of the three-phase AC asynchronous motor of the target locomotive traction system is constructed; Vector control with rotor flux orientation is applied to the dynamic model of a three-phase AC asynchronous motor to obtain the control system model; Based on the command output of the control system model, the DC voltage is output as the stator input voltage of the three-phase AC motor through space vector modulation, so as to construct the dynamic model of the frequency converter based on the stator input voltage of the three-phase AC motor. An initial locomotive model is generated based on the control system model, the dynamic model of the three-phase AC asynchronous motor, and the dynamic model of the frequency converter.

[0025] In actual operation, under the synchronous rotation coordinate system of the rotor flux linkage, the stator input voltage of the three-phase asynchronous motor is: 、 Stator current is generated under the influence of stator self-inductance parameters, rotor mutual inductance parameters, and load impedance. , The stator current further interacts with the motor's magnetic field to generate electromagnetic torque. Change the mechanical speed of the motor This is the mechanical dynamic process of the motor, which allows us to construct a dynamic model of the three-phase AC asynchronous motor of the target locomotive traction system. For example... Figure 4 As shown, the dynamic model of a three-phase AC asynchronous motor details the above process, in which... For rotor self-inductance, For load resistance, For rotor leakage inductance, For stator leakage inductance, for total leakage inductance of both stator and rotor , For the mutual inductance between the stator and rotor, the electromagnetic time constant of the rotor is: Leakage ,in , This represents the rotor flux linkage amplitude. The rotor flux linkage speed, The rotor's mechanical speed. It is an extreme logarithm.

[0026] Furthermore, such as Figure 5 As shown, this embodiment of the invention performs rotor flux-oriented vector control on a dynamic model of a three-phase AC asynchronous motor to obtain a control system model. The control system model employs a dual-closed-loop cascade control, where the outer loop controls the motor speed and flux linkage, and the inner loop controls the motor current. Furthermore, to suppress oscillations, this embodiment of the invention also includes... t Active damping control is superimposed on the axis to increase the system damping.

[0027] Specifically, the input to the control system model is a given rotational speed. Given a magnetic flux DC-side grid voltage sampling value Magnetic flux measurement value The output of the control system model is the control command for the DC / AC converter. 、 . 、 It is an inner-loop PI controller. The transfer function for the outer loop speed controller is expressed as follows: (1) (2) (3) In the formula, For complex frequency domain variables, for The proportional coefficient of the inner loop controller, for Integral coefficient of the inner loop controller, for The proportional coefficient of the inner loop controller, for The proportional coefficient of the inner loop controller, This is the proportional coefficient of the outer loop controller. This represents the integral coefficient of the outer loop controller.

[0028] To eliminate Figure 5 Dynamic model of a three-phase AC asynchronous motor axis, The coupling of the shafts introduces a feedforward term into the control system model to achieve... axis, Axis decoupling.

[0029] Furthermore, in this embodiment of the invention, the DC voltage is output via space vector modulation according to the instruction output of the control system model to generate the stator input voltage of the three-phase AC motor, so as to construct the dynamic model of the frequency converter based on the stator input voltage of the three-phase AC motor.

[0030] Specifically, based on the command output of the control system model, the DC voltage is output as the stator input voltage of the three-phase AC motor via space vector modulation. When the DC voltage... Voltage rating hour: (4) in, This refers to the stator input voltage vector of a three-phase AC motor. The modulation ratio, * The input vector is the stator voltage of the three-phase AC motor. In steady state, the modulation ratio is always set to... track * .

[0031] When DC voltage u dc The sudden change is no longer equal to the voltage rating. At this time, the frequency converter can be described by the following formula: (5) In the formula, * This is the stator voltage vector given by the rated DC side voltage. If copper and iron losses are ignored, the AC power of the inverter is equal to the DC power, resulting in the following relationship: (6) In the formula, This refers to the DC-side current of the frequency converter. For the electromagnetic power of the asynchronous motor, For electromagnetic torque, This represents the rotor's mechanical speed.

[0032] In summary, formulas (4)-(6) constitute the following... Figure 7 The variable frequency drive (VFD) dynamic model is shown.

[0033] Considering the small inductance of the line connecting the traction grid to the locomotive's DC-side capacitor, this embodiment of the invention will subsequently ignore this line and inductance, i.e., the traction grid voltage... and the DC side capacitor voltage of the frequency converter No distinction is made.

[0034] Furthermore, such as Figure 7 As shown, the dynamic model of the three-phase AC asynchronous motor is decoupled according to the feedforward control strategy of the control system model to generate a detailed electromagnetic transient model of the locomotive.

[0035] In step 302, an equivalent power model for the instantaneous AC / DC side is constructed to replace the rotor flux tracking dynamic process of the initial locomotive model, thereby achieving an accurate description of the transient initial stage of the motor at the DC port of the motor inverter. Furthermore, the current inner loop dynamic process of the initial locomotive model is ignored, so as to retain the speed outer loop control model and the active damping feedforward control model of the initial locomotive model, resulting in a locomotive model that considers the influence of DC grid voltage and mechanical speed.

[0036] In some embodiments, an equivalent power model for the instantaneous AC / DC side is constructed to replace the rotor flux tracking dynamic process of the initial locomotive model, thereby achieving an accurate description of the transient initial stage of the motor at the DC port of the motor inverter. Furthermore, the current inner loop dynamic process of the initial locomotive model is ignored, while retaining the speed outer loop control model and the active damping feedforward control model of the initial locomotive model. This results in a locomotive model that considers the influence of DC grid voltage and mechanical speed, including: The current inner loop feedforward of the initial locomotive model is merged, and the overall transfer function of the current inner loop is used to replace the path gain from the current setpoint to the actual current value in order to obtain the initial locomotive traction system model. An equivalent power model for the AC / DC side is constructed to replace the flux delay element in the open-loop control of the flux linkage in the initial locomotive traction system model. This allows for accurate description of the transient start-up phase of the motor at the DC port of the motor inverter. Furthermore, the dynamic process of the inner current loop in the initial locomotive traction system model is ignored, while retaining the outer speed control model and the active damping feedforward control model of the initial locomotive traction system model. This results in a locomotive model that considers the influence of DC grid voltage and mechanical speed.

[0037] In actual implementation, when designing the current inner loop in the embodiments of the present invention, current inner loop feedforward can be used to achieve... m axis, t Decoupling of shaft current. Specifically, such as... Figure 8 As shown, the current inner loop feedforward is merged and replaced by the overall transfer function of the current inner loop. Figure 7 The path gain from the given current value to the actual current value. The inner current loop... and rotational speed outer ring The open-loop transfer function is: (7) (8) in, , These are the parameters for the inner current loop PI. For total leakage inductance of stator and rotor, , For the outer loop PI parameters of the rotational speed, Let be the equivalent transfer function of the inner current loop. Let be the moment of inertia.

[0038] For example, based on the conditions of a certain urban rail transit line in China, =10、 =0.05 、 =200、 =0.017、 =100、 =0.005, which yields the following: Figure 9 The outer speed loop and inner current loop shown (in the image) m Taking the shaft as an example, the Bode plot amplitude-frequency response curve of the closed-loop transfer function shows that the bandwidth of the current inner loop in the system can reach about 14 times that of the speed outer loop. Since the current inner loop regulation is much faster than the speed outer loop, the current inner loop can be simplified to ideal tracking, meaning that the dynamics of the current inner loop can be ignored under rated DC grid voltage. , It should be noted that when the DC voltage... When a sudden change occurs, the amplitude of the AC voltage output by the frequency converter will be affected at the moment of the fault, therefore it is necessary to maintain the value in the inner loop. .

[0039] Furthermore, neglecting copper and iron losses in the locomotive traction system, the active power on the AC side of the locomotive traction system is approximately its electromagnetic power. Therefore, the electromagnetic power on the AC side of the locomotive traction system under steady state is... DC-side power They should be equal, that is: (9) In transient states, there is no clear relationship between the instantaneous values ​​of the electromagnetic power on the AC side and the power on the DC side of the locomotive traction system. Considering that the locomotive speed remains essentially constant during the voltage drop, this embodiment of the invention can be regarded as a constant impedance. Therefore, in the initial stage of a fault transient with minimal control impact, the locomotive power should return to its original value. times, and by Figure 8 It can be seen that at the instant of the fault, the electromagnetic power only changes to the original value. If the power ratio is multiples of 1, then the AC / DC power relationship (i.e., the equivalent instantaneous power model of the AC / DC side) should be corrected in the early stages of the fault as follows: (10) In the later stages of the fault, the power should recover to a new steady state as the speed outer ring is adjusted, at which point formula (9) holds true again. If the AC / DC power relationship coefficients are directly modified, different coefficients need to be used in the early and late stages of the fault, which is very inconvenient.

[0040] Therefore, as Figure 10 As shown, this embodiment of the invention proposes an equivalent model for instantaneous power on both AC and DC sides, by replacing the flux delay element in the open-loop flux control. The AC / DC power relationship is modified to obtain a locomotive model that considers the effects of DC grid voltage and mechanical speed. This allows the DC power to be equal to the original value in the initial stage of a fault. u dc / U dcn ) 2 The model satisfies the AC / DC power relationship in the early stage of the fault, and in the late stage of the fault, due to the effect of the inner current loop, the DC power and electromagnetic power automatically recover to the steady-state equality. In the middle stage of the fault, the adjustment of the outer speed loop and active damping will dominate the transient waveform and reduce the influence of the correction, so that the proposed model can fit the actual locomotive traction system characteristics throughout the entire dynamic process.

[0041] Note that during DC grid voltage disturbances, the above model block diagram includes not only the input of edge-damped feedforward. Changes in the gain of the inner current loop This also changes, resulting in a situation where both input and system parameters change. Figure 10 The system of equations corresponding to the model is as follows: (11) In the formula, This refers to the DC-side current of the frequency converter. For electromagnetic torque, For mechanical torque, For rotational inertia, This refers to the DC-side capacitor voltage of the frequency converter. Let the rotational speed be the outer loop transfer function. For complex frequency domain variables, For a given rotational speed, For mechanical rotation speed, For active damping feedforward coefficients, The active damped feedforward time constant is For a given magnetic flux, This is the rated voltage. For extreme logarithms, For mutual inductance between stator and rotor, This is the rotor's self-inductance.

[0042] This model takes into account the effects of locomotive speed outer-loop regulation, active damping regulation, and DC traction network voltage. It is a multi-time-scale dynamic model of electromechanical-electromagnetic coupling, that is, a locomotive model that considers the effects of DC network voltage and mechanical speed.

[0043] It should be noted that the locomotive model considering the influence of DC grid voltage and mechanical speed includes a speed outer loop controller module, an active damping feedforward module, and a power equivalent module. The locomotive model considering the influence of DC grid voltage and mechanical speed receives the DC grid voltage input signal and the mechanical speed input signal. The speed outer loop controller module responds to the mechanical speed input signal. The active damping feedforward module responds to the DC grid voltage input signal. The power equivalent module is configured according to formulas (9)-(10) to correct the AC / DC power relationship and output the locomotive DC current response signal.

[0044] In some embodiments, the present invention further includes: Under the condition of a small disturbance where the change in DC grid voltage of the target locomotive traction system is less than 10% of the rated value, the locomotive model considering the influence of DC grid voltage and mechanical speed is simplified to include a constant power source with a current rise rate limit, a DC-side passive capacitor connected in parallel with the constant power source, and an active damping compensation module connected in parallel with the constant power source. The current rise rate limit value is determined based on the bandwidth of the outer speed loop.

[0045] Specifically, during urban rail transit operation, locomotives not only face large DC voltage disturbances caused by the withdrawal of traction substations, but also small DC voltage disturbances caused by the starting and stopping of nearby locomotives or dynamic voltage adjustments of traction substations. Under these small disturbances, the aforementioned... Figure 10 The proposed model can be further simplified: First, a small disturbance is defined as a change in DC voltage at the locomotive end that is less than 10% of the rated DC voltage, and the following relationship is assumed to hold: (12) That is to say, it is believed that It is approximately constant, but its rate of change is not negligible. Considering the large moment of inertia of the locomotive under small disturbance conditions, the locomotive speed is also assumed to be approximately constant. Based on the proposed model, we have: (13) in, This represents the total current of the locomotive. This is the current of the locomotive converter (excluding the DC-side capacitor current of the locomotive). For complex frequency domain variables, For the DC side capacitor of the locomotive, This is the DC grid voltage.

[0046] In equation (13), the second term on the right side of the equal sign represents the current on the DC-side capacitor of the locomotive converter, which is a passive damping. Under small disturbance conditions, it is superimposed with the capacitor current component on the DC-side current. According to Figure 10 The simplified DC-side current can be obtained. The expression is as follows: (14) in: (15) (16) (17) in, This represents the equivalent proportionality coefficient of the outer ring rotational speed in the new model. , These are the proportional and integral coefficients of the speed PI controller, respectively. For extreme logarithms, For mutual inductance between stator and rotor, For rotor self-inductance, For a given magnetic flux, For rotational inertia, For a given rotational speed, For complex frequency domain variables, The outer loop integral coefficients of the equivalent rotational speed in the new model. The equivalent gain of the active damped feedforward in the new model, For the gain of the active damped feedforward, The time constant of the feedforward with damping is . For mechanical torque. Under small disturbance conditions, the variables on the left side of equations (15)-(19) are all constants.

[0047] Current In the middle, the DC-side compensation current generated by the active damped feedforward for: (18) DC-side basic current generated by speed outer loop regulation for: (19) therefore, Figure 10 The effect of active damped feedforward can be equivalent to the output. Therefore, Figure 10 The model is transformed into, for example Figure 11 The locomotive equivalent model shown is under small disturbance conditions.

[0048] Under small disturbance conditions, the rotational speed and DC grid voltage amplitude remain basically unchanged. Therefore, in equation (19), except for the denominator... There are no external variables, therefore the box Figure 11 middle Multiply Received The system remains constant. Therefore, under small disturbance conditions, neglecting active damped feedforward, the system becomes a constant power source. However, if the compensation current caused by active damped feedforward... The impact on locomotive current is relatively large during transient regulation. The impact is far greater than Or when the DC side capacitor current of the locomotive affects When the impact is significant, the system's external behavior is approximately that of a constant power source with passive and active damping compensation.

[0049] Active damped feedforward term It can also be simplified. According to the final value theorem, the first and third terms on the right side of equation (18) are both 0 in the steady-state time domain and are approximately unchanged in the transient state under small perturbation conditions. Therefore, only the second term can be retained and expressed as: And can further... It can be simplified to a first-order inertial differential element.

[0050] The model proposed under small perturbation conditions approximates a constant power source with active damping, and can... Simplified to steady-state power constant divided by actual voltage This approach is entirely feasible for simulating small disturbance transients in locomotives, but it also has some drawbacks. With this approach, the current will change during a step drop in the DC-side grid voltage. The locomotive traction system's total current increased instantaneously. In the early stages of a fault, the drop characteristics are achieved entirely through active damping feedforward compensation and DC-side capacitance, which can easily lead to an overestimation of the active damping feedforward gain and DC-side capacitance in the model.

[0051] By providing Increasing the rate of ascent limit can preserve the effect of the locomotive traction system's own damping. In the corrected constant power source, the current rise rate of the locomotive should be similar to that when the outer speed loop dominates in the third stage. This paper presents a formula for estimating the current rise slope using the bandwidth of the outer speed loop: (20) in, The slope of the current recovery rate in the third stage after the grid voltage drop. The bandwidth of the outer loop of the rotational speed is given. The coefficients in this formula are determined as follows: The system without active damping is approximated as an ideal second-order element with DC side voltage as input, DC side current as output, and damping ratio of 0.707. The slope of the step response signal of the second-order element at the point when the influence of active damping basically ends is taken as the power source slope limit value. According to the active damping parameters of a locomotive on a certain urban rail line in China, the adjustment time of the active damping element is considered when the step response of the active damping element decays to 2% of its maximum value. Under the assistance of simulation, the slope of the ideal second-order element step response curve at 1.4 times its maximum value is taken as the approximate current rise rate limit value. Since the slope limit value only reflects the inertia of the locomotive system without active damping, formula (20) can be applied to other locomotive traction systems without relying on the parameters of active damping. In practice, the current rise rate limit value can also be corrected by various methods according to the outer loop structure.

[0052] like Figure 12 As shown, after simplifying the small perturbation as described above, the proposed model is simplified into a constant power source model with passive capacitive damping and active damping, constrained by the rate of current rise. Among them, For active damped feedforward gain, This refers to the capacitor on the DC side of the frequency converter for the locomotive traction system.

[0053] Figure 12 The proposed model is an improvement on the constant power model that has been widely used in the system simulation of traction power supply systems for urban rail transit. It reveals that the proposed model can be approximated as a constant power source model with DC-side passive capacitor damping and active damping when there is a small disturbance or when the active damping compensation is large. It also clarifies the structure that the constant power model should have, the applicable scope of the constant power model, and the correct tuning method for the current rise rate limit of the constant power model.

[0054] It should be noted that those skilled in the art can perform global collaborative simulation of the locomotive model constructed in this embodiment of the invention, which considers the influence of DC grid voltage and mechanical speed, using multiple bidirectional converters and multiple locomotives connected to the overhead contact line, in order to analyze the dynamic interaction between the bidirectional converters and the locomotives; and then, based on the simulation results, evaluate the stability of the system, optimize the collaborative control strategy of the bidirectional converters, or perform system fault diagnosis.

[0055] In summary, the urban rail transit locomotive modeling method proposed in this embodiment, which considers DC grid voltage and mechanical speed, ignores the inner current loop regulation and flux tracking process in the locomotive traction system, while retaining the outer speed loop and active damping feedforward. This model reduces model complexity and achieves an accurate description of the locomotive's transient response when DC grid voltage drops. It overcomes the shortcomings of traditional detailed dynamic models, which are difficult to perform mechanism analysis and have low simulation efficiency. It also makes up for the inability of commonly used equivalent power source models to reflect the transient mechanism of large disturbances. This provides an efficient and accurate modeling tool for electromagnetic transient simulation of traction power supply systems under large disturbance conditions.

[0056] Next, referring to the accompanying drawings, we describe the urban rail transit locomotive modeling device that considers DC grid voltage and mechanical speed according to an embodiment of the present invention.

[0057] Figure 13 This is a block diagram of an urban rail transit locomotive modeling device that considers DC grid voltage and mechanical speed, provided in an embodiment of the present invention.

[0058] like Figure 13 As shown, the urban rail transit locomotive modeling device 130, which considers DC grid voltage and mechanical speed, includes: a first model building module 1301 and a second model building module 1302.

[0059] The component model construction module 1301 is used to construct the initial locomotive model of the target locomotive traction system. The locomotive model construction module 1302 is used to construct the AC / DC side instantaneous power equivalent model to replace the rotor flux tracking dynamic process of the initial locomotive model, so as to realize the accurate description of the transient start-up stage of the motor at the DC port of the motor inverter. Furthermore, the current inner loop dynamic process of the initial locomotive model is ignored, so as to retain the speed outer loop control model and active damping feedforward control model of the initial locomotive model, thus obtaining a locomotive model that considers the influence of DC grid voltage and mechanical speed.

[0060] In some embodiments, the first model construction module 1301 includes: The three-phase AC asynchronous motor dynamic model building unit is used to build a dynamic model of the three-phase AC asynchronous motor of the target locomotive traction system under the synchronous rotation coordinate system of the rotor flux linkage. The control system model building unit is used to perform rotor flux orientation vector control on the dynamic model of a three-phase AC asynchronous motor to obtain the control system model; The inverter dynamic model building unit is used to output the DC voltage through space vector modulation to the stator input voltage of the three-phase AC motor according to the instruction output of the control system model, so as to build the inverter dynamic model based on the stator input voltage of the three-phase AC motor. The locomotive model building unit is used to generate an initial locomotive model based on the control system model, the three-phase AC asynchronous motor dynamic model, and the frequency converter dynamic model.

[0061] In some embodiments, the second model construction module 1302 includes: The merging and substitution unit is used to merge the current inner loop feedforward of the initial locomotive model and replace the path gain from the current setpoint to the actual current value with the overall transfer function of the current inner loop to obtain the initial locomotive traction system model. The building unit is used to ignore the flux delay element of the open-loop control in the initial locomotive traction system model in order to build an equivalent model of instantaneous power on the AC and DC sides; The replacement and retention unit is used to construct the AC / DC side instantaneous power equivalent model to replace the rotor flux tracking dynamic process of the initial locomotive model, so as to realize the accurate description of the transient start stage of the motor at the DC port of the motor inverter. Furthermore, the current inner loop dynamic process of the initial locomotive model is ignored, so as to retain the speed outer loop control model and active damping feedforward control model of the initial locomotive model, thus obtaining a locomotive model that considers the influence of DC grid voltage and mechanical speed.

[0062] In some embodiments, the locomotive model considering the influence of DC grid voltage and mechanical speed includes a speed outer loop controller module, an active damping feedforward module, and a power equivalent module, wherein... The outer loop speed controller module is used to respond to the input mechanical speed signal; An active damped feedforward module is used to respond to the input DC grid voltage signal; The power equivalent module is used to correct the AC / DC power relationship to output the locomotive DC current response signal.

[0063] In some embodiments, the locomotive model considering the influence of DC grid voltage and mechanical speed is specifically expressed as follows:

[0064] In the formula, This refers to the DC-side current of the frequency converter. For electromagnetic torque, For mechanical torque, For rotational inertia, This refers to the DC-side capacitor voltage of the frequency converter. Let the rotational speed be the outer loop transfer function. For complex frequency domain variables, For a given rotational speed, For mechanical rotation speed, For active damping feedforward coefficients, The active damped feedforward time constant is For a given magnetic flux, This is the rated voltage. For extreme logarithms, For mutual inductance between stator and rotor, This is the rotor's self-inductance.

[0065] In some embodiments, it also includes: The small disturbance simplification module is used to simplify the locomotive model, which considers the influence of DC grid voltage and mechanical speed, under the condition that the change in DC grid voltage of the target locomotive traction system is less than 10% of the rated value. The model includes a constant power source with a current rise rate limit, a DC-side passive capacitor connected in parallel with the constant power source, and an active damping compensation module connected in parallel with the constant power source. The current rise rate limit value is determined based on the bandwidth of the outer speed loop.

[0066] It should be noted that the foregoing explanation of the urban rail transit locomotive modeling method embodiment considering DC grid voltage and mechanical speed also applies to the urban rail transit locomotive modeling device considering DC grid voltage and mechanical speed in this embodiment, and will not be repeated here.

[0067] The urban rail transit locomotive modeling device proposed in this embodiment of the invention, which considers DC grid voltage and mechanical speed, ignores the inner current loop regulation and flux tracking process in the locomotive traction system, while retaining the outer speed loop and active damping feedforward. This locomotive traction system model reduces model complexity and achieves an accurate description of the locomotive's transient response when the DC grid voltage drops. It overcomes the shortcomings of traditional detailed dynamic models, which are difficult to perform mechanism analysis and have low simulation efficiency. It also makes up for the inability of commonly used equivalent power source models to reflect the transient mechanism of large disturbances. It provides an efficient and accurate modeling tool for electromagnetic transient simulation of traction power supply systems under large disturbance conditions.

[0068] Figure 14 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention.

[0069] The electronic device may include: a memory 1401, a processor 1402, and a computer program stored on the memory 1401 and executable on the processor 1402.

[0070] When the processor 1402 executes the program, it implements the urban rail transit locomotive modeling method that considers DC grid voltage and mechanical speed provided in the above embodiments.

[0071] Furthermore, electronic devices also include: Communication interface 1403 is used for communication between memory 1401 and processor 1402.

[0072] The memory 1401 is used to store computer programs that can run on the processor 1402.

[0073] The memory 1401 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage.

[0074] If the memory 1401, processor 1402, and communication interface 1403 are implemented independently, then the communication interface 1403, memory 1401, and processor 1402 can be interconnected via a bus to complete communication between them. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of representation, Figure 14 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0075] Optionally, in a specific implementation, if the memory 1401, processor 1402, and communication interface 1403 are integrated on a single chip, then the memory 1401, processor 1402, and communication interface 1403 can communicate with each other through an internal interface.

[0076] The processor 1402 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present invention.

[0077] This invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described urban rail transit locomotive modeling method considering DC grid voltage and mechanical speed.

[0078] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0079] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0080] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0081] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0082] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. If implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0083] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0084] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0085] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A modeling method for urban rail transit locomotives considering DC grid voltage and mechanical speed, characterized in that, Includes the following steps: Construct an initial locomotive model for the target locomotive traction system; An equivalent power model for the AC / DC side is constructed to replace the rotor flux tracking dynamic process of the initial locomotive model, achieving an accurate description of the transient initial stage of the motor at the DC port of the motor inverter. Furthermore, the inner current loop dynamic process of the initial locomotive model is ignored, while retaining the outer speed control model and active damping feedforward control model of the initial locomotive model. This results in a locomotive model that considers the influence of DC grid voltage and mechanical speed, specifically including: The current inner loop feedforward of the initial locomotive model is combined, and the overall transfer function of the current inner loop is used to replace the path gain from the current setpoint to the actual current value to obtain the initial locomotive traction system model. An equivalent power model for the AC / DC side is constructed to replace the flux delay element in the open-loop flux control of the initial locomotive traction system model. This allows for accurate description of the transient initial stage of the motor at the DC port of the motor inverter. Furthermore, the dynamic process of the inner current loop of the initial locomotive traction system model is ignored, while retaining the outer speed control model and the active damping feedforward control model of the initial locomotive traction system model. This yields the locomotive model considering the influence of DC grid voltage and mechanical speed. The specific expression for the locomotive model considering the influence of DC grid voltage and mechanical speed is as follows: In the formula, This refers to the DC-side current of the frequency converter. For electromagnetic torque, For mechanical torque, For rotational inertia, This refers to the DC-side capacitor voltage of the frequency converter. Let the rotational speed be the outer loop transfer function. For complex frequency domain variables, For a given rotational speed, For mechanical rotation speed, For active damping feedforward coefficients, The active damped feedforward time constant is For a given magnetic flux, This is the rated voltage. For extreme logarithms, For mutual inductance between stator and rotor, This is the rotor's self-inductance.

2. The urban rail transit locomotive modeling method considering DC grid voltage and mechanical speed according to claim 1, characterized in that, The initial locomotive model for constructing the target locomotive traction system includes: In the synchronous rotation coordinate system of the rotor flux linkage, a dynamic model of the three-phase AC asynchronous motor of the target locomotive traction system is constructed; The dynamic model of the three-phase AC asynchronous motor is subjected to rotor flux orientation vector control to obtain the control system model; According to the instructions output of the control system model, the DC voltage is space vector modulated to output the three-phase AC motor stator input voltage, so as to construct the frequency converter dynamic model based on the three-phase AC motor stator input voltage; The initial locomotive model is generated based on the control system model, the three-phase AC asynchronous motor dynamic model, and the frequency converter dynamic model.

3. The urban rail transit locomotive modeling method considering DC grid voltage and mechanical speed according to claim 1, characterized in that, The locomotive model considering the influence of DC grid voltage and mechanical speed includes a speed outer loop controller module, an active damping feedforward module, and a power equivalent module, wherein... The outer loop speed controller module is used to respond to the input mechanical speed input signal; The active damping feedforward module is used to respond to the input DC grid voltage signal; The power equivalent module is used to correct the AC / DC power relationship to output the locomotive DC current response signal.

4. The urban rail transit locomotive modeling method considering DC grid voltage and mechanical speed according to claim 1, characterized in that, Also includes: Under the small disturbance condition that the change in DC grid voltage of the target locomotive traction system is less than 10% of the rated value, the locomotive model considering the influence of DC grid voltage and mechanical speed is simplified to include a constant power source with a current rise rate limit, a DC-side passive capacitor connected in parallel with the constant power source, and an active damping compensation module connected in parallel with the constant power source, wherein the current rise rate limit value is determined based on the bandwidth of the outer speed loop.

5. A modeling device for urban rail transit locomotives considering DC grid voltage and mechanical speed, characterized in that, include: The first model construction module is used to construct the initial locomotive model of the target locomotive traction system; The second model construction module is used to construct an equivalent instantaneous power model on both the AC and DC sides to replace the rotor flux tracking dynamic process of the initial locomotive model. This achieves an accurate description of the transient initial stage of the motor at the DC port of the motor inverter. Furthermore, it ignores the inner current loop dynamic process of the initial locomotive model, retaining the outer speed control model and active damping feedforward control model of the initial locomotive model. This results in a locomotive model that considers the influence of DC grid voltage and mechanical speed, specifically including: The merging and substitution unit is used to merge the current inner loop feedforward of the initial locomotive model and replace the path gain from the current setpoint to the actual current value with the overall transfer function of the current inner loop to obtain the initial locomotive traction system model. The building unit is used to ignore the flux delay element of the open-loop control in the initial locomotive traction system model in order to build an equivalent model of instantaneous power on the AC and DC sides; The replacement and retention unit is used to construct an equivalent power model for the AC / DC side instantaneous power, replacing the rotor flux tracking dynamic process of the initial locomotive model. This achieves an accurate description of the transient initial stage of the motor at the DC port of the motor inverter. Furthermore, the current inner loop dynamic process of the initial locomotive model is ignored, while retaining the speed outer loop control model and the active damping feedforward control model of the initial locomotive model. This results in a locomotive model considering the influence of DC grid voltage and mechanical speed. The specific expression for the locomotive model considering the influence of DC grid voltage and mechanical speed is as follows: In the formula, This refers to the DC-side current of the frequency converter. For electromagnetic torque, For mechanical torque, For rotational inertia, This refers to the DC-side capacitor voltage of the frequency converter. Let the rotational speed be the outer loop transfer function. For complex frequency domain variables, For a given rotational speed, For mechanical rotation speed, For active damping feedforward coefficients, The active damped feedforward time constant is For a given magnetic flux, This is the rated voltage. For extreme logarithms, For mutual inductance between stator and rotor, This is the rotor's self-inductance.

6. An electronic device, characterized in that, include: The system includes a memory, a processor, and a computer program stored in the memory and executable on the processor, the processor executing the program to implement the urban rail transit locomotive modeling method considering DC grid voltage and mechanical speed as described in any one of claims 1-4.

7. A computer program product, characterized in that, When a computer program / instruction is executed by a processor, it implements the urban rail transit locomotive modeling method that considers DC grid voltage and mechanical speed as described in any one of claims 1-4.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, The program is executed by the processor to implement the urban rail transit locomotive modeling method considering DC grid voltage and mechanical speed as described in any one of claims 1-4.

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