Safety interval control method for heavy haul train group operation

Abstract

The invention discloses a safety interval control method for heavy-load train group operation, which belongs to the technical field of rail transit, and comprises the following steps: acquiring actual operation data of heavy-load train units, and constructing train longitudinal dynamic constraints and safety interval constraints; the braking process of the forward heavy-load train unit is gradually close to the optimum based on the braking track of the backward heavy-load train unit; and calculating the minimum tracking distance of the train in real time based on the braking tracks of the forward heavy-load train unit and the backward heavy-load train unit in the operation of the heavy-load train group. According to the method, the limitation of a traditional fixed braking rate model is broken through, the tracking interval can be effectively shortened by optimizing the braking process of the forward heavy haul train unit, and safe and efficient operation of the heavy haul railway group train is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of rail transit technology, and in particular to a method for controlling safe intervals for heavy-load train group operations. Background Technology

[0002] Heavy-haul railways, as the core mode of bulk freight transportation, are characterized by large traction capacity and high transportation efficiency, playing a vital role in my country's comprehensive transportation system. With the development of "heavy freight transport," traditional fixed-formation trains are no longer sufficient to meet capacity demands. Train group operation, utilizing car-to-car communication technology and collaborative control methods, aims to reduce train intervals and increase line capacity without altering the physical formation structure, representing a crucial development direction for improving the quality and efficiency of heavy-haul railways. However, compared to passenger-freight shared lines and light-load trains, heavy-haul trains are characterized by high load capacity, large inertia, slow braking response, and long air brake system charging and discharging times, posing more severe challenges to train safety protection in group operation scenarios.

[0003] There is an urgent need to improve transportation efficiency through train group operations; however, existing research has significant limitations. In calculating safe protection distances, widely used models are typically based on a fixed braking rate assumption, which assumes that the preceding heavy-load train unit always brakes with emergency braking deceleration. This fails to fully consider the dynamic changes and uncertainties in the braking behavior of the preceding heavy-load train unit during actual operation. Furthermore, the lack of integration between safe separation control and braking mitigation strategies may lead to problems such as frequent braking or insufficient safety margins.

[0004] Therefore, there is an urgent need to propose a safe interval control method that integrates the characteristics of air braking systems. By optimizing the minimum train tracking distance, the train tracking distance can be effectively shortened, providing technical support for the safe and efficient operation of heavy-haul train groups. Summary of the Invention

[0005] The purpose of this invention is to overcome the technical problems of insufficient safety protection and poor adaptability of safety interval control strategies in the prior art, and to provide a safety interval control method for heavy-load train group operation.

[0006] To address the aforementioned technical problems, the present invention provides the following technical solution: A safety interval control method for heavy-haul train group operation includes the following steps: S1: Real-time collection of data related to the operation of heavy-haul trains, including: operating status, road condition information, and communication status information; S2: Construct longitudinal dynamic constraints for the train based on the relevant data on the operation of the heavy-haul train; S3: Construct safety interval constraints between the forward heavy-load train unit and the rear heavy-load train unit based on the aforementioned train longitudinal dynamic constraints; S4: During the current sampling period, under the conditions of satisfying the longitudinal dynamic constraints and the safety interval constraints, the braking process of the forward heavy-load train unit is optimized with the goal of minimizing the safe tracking interval between the forward heavy-load train unit and the following heavy-load train unit. S5: Recalculate the braking distance between the preceding heavy-load train unit and the following heavy-load train unit, and calculate the required safe tracking interval in real time; S6: Construct safety constraint triggering conditions and braking system physical constraints; compare the current actual distance with the required safe tracking interval to determine the feasibility of braking relief; perform the relief operation only when the safety constraint triggering conditions and braking system physical constraints are met simultaneously. After the operation is completed, enter the next sampling cycle and repeat steps S4-S6.

[0007] As a preferred embodiment of the present invention, the operating state described in step S1 includes: the real-time position, speed, and acceleration of the forward heavy-load train unit and the rear heavy-load train unit; The road condition information includes: the gradient, curve radius, and corresponding speed limits of the current section and the section ahead; The communication status information includes: vehicle-to-vehicle communication link quality and group control center communication status.

[0008] As a preferred embodiment of the present invention, step S2 includes: using a single-mass model to describe the operating state of the heavy-haul train, wherein the longitudinal acceleration of the heavy-haul train is determined by the traction force / braking force and the running resistance, wherein the running resistance includes basic resistance and additional resistance, and the additional resistance is caused by gradient, curve and tunnel.

[0009] As a preferred embodiment of the present invention, the conditions for the train longitudinal dynamic constraints constructed in step S2 are as follows: ;in, For train speed, For acceleration, F t For traction force, F b For braking force, F r As the basic resistance, F w To add resistance, This refers to the total mass of the train.

[0010] As a preferred embodiment of the present invention, step S3 includes: under the longitudinal dynamic constraints of the train, calculating the braking distances of the preceding heavy-load train unit and the following heavy-load train unit from the current moment to brake and stop, and constructing a safe interval constraint to ensure that no rear-end collision occurs during the entire braking process; In the process of calculating braking distance, the braking rate is regarded as a parameter that changes dynamically with track conditions, train status and environmental factors.

[0011] As a preferred embodiment of the present invention, the conditions for constructing the safety interval constraint in step S3 are as follows: ; in, Indicates the safe tracking interval; , Representing any time point The rear position of the forward heavy-haul train unit and the front position of the rear heavy-haul train unit; , These represent the stopping times. The rear position of the forward heavy-haul train unit and the front position of the rear heavy-haul train unit; This indicates a safety margin.

[0012] As a preferred embodiment of the present invention, step S4 includes: based on the known operating status of the following heavy-load train unit, the following heavy-load train unit is preset to brake at the maximum service braking deceleration, and the braking trajectory of the following heavy-load train unit and the distance from the current moment to braking and stopping are calculated; based on this, combined with the known operating status of the preceding heavy-load train unit, track data and preset safety margin range, according to the principle of relative braking distance, and under the condition of satisfying the longitudinal dynamic constraints and the safety interval constraints, the predicted braking trajectory of the preceding heavy-load train unit is obtained with the optimization objective of minimizing the safe tracking interval between the preceding heavy-load train unit and the following heavy-load train unit.

[0013] As a preferred embodiment of the present invention, step S5 includes: obtaining an electric braking control sequence based on actual operating data and driver operating experience, superimposing it on the air braking force to correct the deceleration of the train, and recalculating the braking distance between the preceding heavy-load train unit and the following heavy-load train unit.

[0014] Compared with the prior art, the advantages of the present invention are as follows: This invention utilizes the braking trajectory of the following heavy-haul train unit to gradually approach the optimal braking process of the preceding heavy-haul train unit; and calculates the minimum tracking interval in real time based on the braking trajectories of the preceding and following heavy-haul train units during group operation. This invention overcomes the limitations of traditional fixed braking rate models, effectively shortening the tracking interval by optimizing the braking process of the preceding heavy-haul train unit, thus ensuring the safe and efficient operation of heavy-haul railway train groups. Attached Figure Description

[0015] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. In the drawings: Figure 1 This is a flowchart of a safety interval control method for heavy-haul train group operation as described in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram illustrating the protection of heavy-haul train group operation according to a safety interval control method for heavy-haul train group operation as described in Embodiment 1 of the present invention. Figure 3 This is a flowchart illustrating the online determination of whether to implement mitigation in a safety interval control method for heavy-load train group operation as described in Embodiment 1 of the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0017] Example 1 A safety interval control method for heavy-haul train group operation includes the following steps: S1: Real-time collection of data related to the operation of heavy-haul trains, including: operating status, road condition information, and communication status information; Preferably, the operating state described in step S1 includes: the real-time position, speed, and acceleration of the forward heavy-load train unit and the rear heavy-load train unit; The road condition information includes: the gradient, curve radius, and corresponding speed limits of the current section and the section ahead; The communication status information includes: vehicle-to-vehicle communication link quality and group control center communication status.

[0018] Specifically, the relevant data on the operation of the heavy-haul train are collected in real time through vehicle-to-vehicle communication, vehicle-to-ground communication and on-board sensors, with a sampling period of no more than 0.2 seconds.

[0019] Specifically, such as Figure 2As shown, describing the operating state is crucial for simulating the operation of heavy-haul train groups. Although heavy-haul trains typically consist of locomotives and multiple carriages, in group mode, train units operate in a virtual coupled manner, which significantly reduces the coupling forces between vehicles and effectively mitigates longitudinal impulses. Therefore, this invention uses a more computationally efficient single-mass model for research, in which each heavy-haul train unit has the same position and velocity. This simplification significantly reduces the computational complexity of the control system.

[0020] In train operation status calculations, the braking rate is considered a dynamically changing parameter that varies with track conditions, train status, and environmental factors (such as gradient, curve radius, and wind speed). The braking rates of both the preceding and following heavy-load train units are dynamically adjusted according to actual operating conditions. Changes in track conditions, differences in braking performance among different vehicles, and variations in train formation all lead to real-time changes in the train's braking rate. This dynamic adjustment mechanism more accurately reflects the actual braking process of the train, overcoming the limitations of traditional methods that ignore changes in braking rate, and enabling a more accurate simulation of the braking distance and follow-up intervals of heavy-load trains under different operating conditions.

[0021] S2: Construct longitudinal dynamic constraints for the train based on the relevant data on the operation of the heavy-haul train; Specifically, in addition to being affected by traction and braking performance, the train's operating status is also influenced by track and environmental factors such as gradient, curve radius, tunnel conditions, and wind speed. To accurately describe the train's longitudinal motion under different operating conditions and to provide a basis for subsequent braking distance calculations, it is necessary to establish longitudinal dynamic constraints on the train based on real-time operating data.

[0022] Based on the acquired data related to the operation of heavy-haul trains, a single-mass model is used to describe the operating state of the train unit: the longitudinal acceleration of the train is determined by the traction / braking force and the running resistance, where the running resistance includes the basic resistance and the additional resistance caused by gradient, curves, tunnels, etc., and it is stipulated that the traction and braking conditions do not occur simultaneously during the actual operation of the train.

[0023] Preferably, the conditions for the train longitudinal dynamic constraints constructed in step S2 are as follows: ; in, For train speed, For acceleration, F t For traction force, F b For braking force, F r As the basic resistance, F w To add resistance, This refers to the total mass of the train.

[0024] S3: Construct safety interval constraints between the forward heavy-load train unit and the rear heavy-load train unit based on the aforementioned train longitudinal dynamic constraints; Specifically, under the aforementioned longitudinal dynamic constraints of the train, the distance S between the preceding heavy-load train unit and the following heavy-load train unit when they brake to a stop from the current moment is calculated. f With S l To construct a safe distance constraint that ensures no rear-end collisions occur during the entire braking process.

[0025] In the braking distance calculation process, the braking rate is regarded as a parameter that dynamically changes with track conditions, train status, and environmental factors, so that S f S l It can more closely resemble the actual braking process.

[0026] Preferably, the conditions for the safety interval constraint constructed in step S3 are: ; in, Indicates the safe tracking interval; , Representing any time point The rear position of the forward heavy-haul train unit and the front position of the rear heavy-haul train unit; , These represent the stopping times. The rear position of the forward heavy-haul train unit and the front position of the rear heavy-haul train unit; This indicates the safety margin, which is a configurable preset parameter determined based on track conditions, train formation, and braking performance.

[0027] The safety interval constraint aims to minimize the train tracking distance within the feasible set, while ensuring the safe operation of the train and meeting the preset safety margin.

[0028] S4: During the current sampling period, under the conditions of satisfying the longitudinal dynamic constraints and the safety interval constraints, the braking process of the forward heavy-load train unit is optimized with the goal of minimizing the safe tracking interval between the forward heavy-load train unit and the following heavy-load train unit. Preferably, step S4 includes: based on the known operating status of the following heavy-load train unit, pre-setting the following heavy-load train unit to brake at the maximum service braking deceleration, and calculating the braking trajectory of the following heavy-load train unit and the braking distance S from the current moment to a stop. f Based on this, and combining the known operating status of the preceding heavy-haul train unit, track data, and preset safety margin range, according to the principle of relative braking distance, and under the conditions of satisfying the longitudinal dynamic constraints and the safety interval constraints, the safe tracking interval between the preceding heavy-haul train unit and the following heavy-haul train unit is determined. DMinimize the predicted braking trajectory of the forward heavy-load train unit as the optimization objective.

[0029] S5: Recalculate the braking distance between the preceding and following heavy-haul train units, and calculate the required safe following interval in real time. D ; Preferably, step S5 includes: obtaining an electric braking control sequence based on actual operating data and driver operating experience, superimposing it on the air braking force to correct the train deceleration, and recalculating the braking distance between the preceding heavy-load train unit and the following heavy-load train unit.

[0030] Specifically, since electric braking force accounts for a relatively small proportion of the overall braking force, air braking still dominates the braking process of heavy-haul trains. Therefore, this invention obtains an electric braking operation sequence based on the analysis of actual train operation data and driver operating experience, and superimposes it as a compensation quantity.

[0031] In practice, the braking distance is first calculated based on air braking; then, the electric braking force is calculated based on the current speed and the preset percentage of electric braking force output, and this is superimposed on the air braking force to correct the train deceleration; finally, the braking distances of the preceding and following heavy-load train units are recalculated to update the safe following interval. D .

[0032] S6: Construct safety constraint triggering conditions and braking system physical constraints; compare the current actual distance with the required safe tracking interval to determine the feasibility of braking relief; perform the relief operation if and only if the safety constraint triggering conditions and braking system physical constraints are met simultaneously. After the operation is completed, enter the next sampling cycle and repeat steps S4-S6.

[0033] Specifically, within each sampling period, the corrected braking distance S of the forward heavy-load train unit is obtained by combining steps S4 and S5. l This allows for the real-time calculation of the required safe tracking interval. D Furthermore, the current actual spacing d With the aforementioned safe tracking interval D The comparison is then performed, and the process for determining the feasibility of brake relief is initiated.

[0034] A mitigation operation is performed only if both the following train longitudinal dynamics constraints and the following safety interval constraints are simultaneously satisfied, and the safety tracking interval is recalculated in the next sampling period after the mitigation operation. D Continue to optimize the braking process in step S4 to shorten the train tracking interval.

[0035] Specifically, such as Figure 3 As shown, an online determination is made as to whether to implement mitigation, and the determination simultaneously meets the following two conditions: 1) Safety constraint triggering conditions: The current actual distance between the rear of the forward heavy-haul train unit car and the front of the following heavy-haul train unit car is denoted as . d When the currently traveling heavy-load train unit continues braking at the current braking level, if This indicates a risk of insufficient safety margin under the given maximum commonly used braking trajectory of the heavy-load train unit, triggering a feasibility assessment for mitigation; if If so, no relief is needed; continue with the current command input.

[0036] 2) Physical constraints of the braking system When the above safety constraint triggering conditions are met, it is also necessary to determine whether sufficient wind pressure can be reserved for the next braking after the relief, which is mainly determined by the following time and speed constraints: Minimum air charging time constraint ( After this release, the auxiliary air cylinder must have at least the specified charging time to achieve the designated braking force during the next braking. Therefore, the time interval between the end of the release and the start of the next braking must meet the following requirements.

[0037] Minimum exhaust time constraint ( Each application of air braking must be accompanied by a specified exhaust time to ensure stable braking force output. Braking shorter than this time is considered ineffective and will damage the system. Therefore, the duration of the air braking application phase must meet the following requirements.

[0038] Minimum relief speed ( To prevent excessive longitudinal internal forces from causing the coupler to break, the train speed during release must not be lower than the minimum release speed. For heavy-haul trains with a capacity of 10,000 tons, this speed must not be lower than 35 km / h.

[0039] Line speed limit ( Train speed must not exceed the speed limit at the current location. When the speed exceeds the speed limit, emergency braking will be triggered, which will not only affect train efficiency but also cause a significant jolt.

[0040] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0041] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0042] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A safety interval control method for heavy-haul train group operation, characterized in that, Includes the following steps: S1: Real-time collection of data related to the operation of heavy-haul trains, including: operating status, road condition information, and communication status information; S2: Construct longitudinal dynamic constraints for the train based on the relevant data on the operation of the heavy-haul train; S3: Construct safety interval constraints between the forward heavy-load train unit and the rear heavy-load train unit based on the aforementioned train longitudinal dynamic constraints; S4: During the current sampling period, under the conditions of satisfying the longitudinal dynamic constraints and the safety interval constraints, the braking process of the forward heavy-load train unit is optimized with the goal of minimizing the safe tracking interval between the forward heavy-load train unit and the following heavy-load train unit. S5: Recalculate the braking distance between the preceding heavy-load train unit and the following heavy-load train unit, and calculate the required safe tracking interval in real time; S6: Construct safety constraint triggering conditions and braking system physical constraints; compare the current actual distance with the required safe tracking interval to determine the feasibility of braking relief; perform the relief operation only when the train safety constraint triggering conditions and braking system physical constraints are met simultaneously. After the operation is completed, enter the next sampling cycle and repeat steps S4-S6.

2. The safety interval control method for heavy-haul train group operation according to claim 1, characterized in that, The operating status mentioned in step S1 includes: the real-time position, speed, and acceleration of the forward heavy-load train unit and the rear heavy-load train unit; The road condition information includes: the gradient, curve radius, and corresponding speed limits of the current section and the section ahead; The communication status information includes: vehicle-to-vehicle communication link quality and group control center communication status.

3. The safety interval control method for heavy-haul train group operation according to claim 1, characterized in that, Step S2 includes: using a single-mass model to describe the operating state of the heavy-haul train. The longitudinal acceleration of the heavy-haul train is determined by the traction / braking force and the running resistance. The running resistance includes basic resistance and additional resistance, which is caused by gradient, curves, and tunnels.

4. A safety interval control method for heavy-haul train group operation according to claim 2, characterized in that, The conditions for the train longitudinal dynamic constraints constructed in step S2 are as follows: ; in, For train speed, For acceleration, F t For traction force, F b For braking force, F r As the basic resistance, F w To add resistance, This refers to the total mass of the train.

5. A safety interval control method for heavy-haul train group operation according to claim 1, characterized in that, Step S3 includes: under the longitudinal dynamic constraints of the train, calculating the braking distances of the preceding heavy-load train unit and the following heavy-load train unit from the current moment to brake and stop, and constructing a safe interval constraint to ensure that no rear-end collision occurs during the entire braking process; In the process of calculating braking distance, the braking rate is regarded as a parameter that changes dynamically with track conditions, train status and environmental factors.

6. A safety interval control method for heavy-haul train group operation according to claim 5, characterized in that, The conditions for the safety interval constraints constructed in step S3 are: ; in, Indicates the safe tracking interval; , Representing any time point The rear position of the forward heavy-haul train unit and the front position of the rear heavy-haul train unit; , These represent the stopping times. The rear position of the forward heavy-haul train unit and the front position of the rear heavy-haul train unit; This indicates a safety margin.

7. A safety interval control method for heavy-haul train group operation according to claim 1, characterized in that, Step S4 includes: based on the known operating status of the following heavy-load train unit, the following heavy-load train unit is pre-set to brake at the maximum service braking deceleration, and the braking trajectory of the following heavy-load train unit and the distance from the current moment to braking and stopping are calculated; based on this, combined with the known operating status of the preceding heavy-load train unit, track data and preset safety margin range, according to the principle of relative braking distance, and under the condition of satisfying the longitudinal dynamic constraints and the safety interval constraints, the predicted braking trajectory of the preceding heavy-load train unit is obtained with the optimization objective of minimizing the safe tracking interval between the preceding heavy-load train unit and the following heavy-load train unit.

8. A safety interval control method for heavy-haul train group operation according to claim 1, characterized in that, Step S5 includes: obtaining an electric braking control sequence based on actual operating data and driver operating experience, superimposing it on the air braking force to correct the train deceleration, and recalculating the braking distance between the preceding heavy-load train unit and the following heavy-load train unit.

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