Train traction calculation method

Abstract

The invention relates to the technical field of railway locomotives, in particular to a train traction calculation method. The train traction calculation method comprises the following steps of: 1, carrying out forward calculation based on a mileage segmented accumulation method, 2, carrying out reverse calculation, and carrying out braking back calculation at a braking end point by back acceleration, and 3, forming a complete calculation method by combining the forward calculation and the braking back calculation. According to the mileage-based segmented accumulation train traction calculation method, the trial and error process of an analysis method at each slope change point can be effectively avoided, the calculation process is simplified, and when the step length is set to be small enough, the calculation process is very accurate. The braking starting point and the initial speed are unknown in the braking process, the conventional forward calculation thought is completed through trial and error, the braking back calculation method is provided, the braking process can be completed through one-time calculation, trial and error or nested loop solving can be avoided, the calculation process is simplified, and the calculation process is very accurate.

Description

Technical Field

[0001] This invention relates to a traction calculation method, and more particularly to a computerized method for train traction calculation. Background Technology

[0002] "Train traction calculation," formerly known as "locomotive operation theory" or "traction calculation science," is a practical discipline that specifically studies the movement of railway trains along tracks under the influence of external forces and related issues. Based on mechanics and drawing upon scientific experiments and advanced operational experience, it analyzes various phenomena and principles in train operation to solve key technical and techno-economic problems in railway operation and design. These include locomotive traction weight, train speed and travel time, train braking distance, braking speed limits, braking capacity, and locomotive energy consumption (fuel or electricity consumption), among others.

[0003] Common methods for calculating train traction during train operation include analytical methods, graphical methods, and equal speed methods. Among these, graphical methods have limited application scenarios, and equal speed methods have higher errors. With the widespread use of computers today, analytical methods have become the programming basis for train traction computer calculations. However, analytical methods are based on segmented accumulation methods of speed intervals, which cannot simulate uniform speed conditions. Furthermore, trial and error methods are frequently used at gradient change points and station entry stopping conditions, resulting in low calculation accuracy and high complexity. Summary of the Invention

[0004] This invention aims to address the aforementioned shortcomings by proposing a train traction calculation method that achieves higher calculation accuracy while avoiding trial and error and simplifying the complexity of the calculation work.

[0005] To overcome the deficiencies in the prior art, the technical solution adopted by the present invention to solve its technical problem is as follows: This train traction calculation method includes:

[0006] Step 1: Perform forward calculation using the segmented cumulative method based on mileage:

[0007] a. Before the vehicle is in operation, input the parameters of vehicle mass, traction / braking characteristics, resistance characteristics, as well as the parameters of the length of the running route, the gradient of the running route, the radius of the curves on the running route, and the parameters of stations and stopping time.

[0008] b. Pre-set the calculation step size, target velocity, and initial simulation velocity, i.e., the step interval ΔS and the target velocity v. aim ;

[0009] c. Establish a driver model, that is, simulate the driver's operation and calculate the traction / braking force of the vehicle operated by the driver at each step length;

[0010] First, calculate the target acceleration:

[0011] ;

[0012] Calculate the target traction / braking force based on the target acceleration; traction is positive, braking force is negative.

[0013] ,

[0014] Among them, resistance is positive when it is opposite to the direction of train travel, and negative when it is the same as the direction of train travel;

[0015] Calculate the actual traction / braking force based on the traction / braking characteristics:

[0016] ;

[0017] d: Using the traction / braking force obtained in step 3, and assuming that the vehicle undergoes uniform acceleration in each step, the vehicle's motion state can be solved according to the principles of mechanics:

[0018] Calculate the actual acceleration:

[0019] ;

[0020] Calculate the final velocity of the step length, and use it as the initial velocity for the next step length calculation:

[0021] ;

[0022] Calculate the step-size average velocity:

[0023] ;

[0024] Calculate the step size running time:

[0025] ;

[0026] Calculate step size consumption / recovery power:

[0027] ;

[0028] Calculate step size energy consumption / recovery:

[0029] ;

[0030] e: Repeat steps three and four to solve the problem in a forward loop until the end of the route;

[0031] The second step is reverse calculation: at the end of braking, accelerate backward to perform braking recalculation.

[0032] a. Solving for the braking force:

[0033] First, calculate the target acceleration:

[0034] ;

[0035] Calculate the target braking force based on the target acceleration:

[0036] ;

[0037] Calculate the actual braking force based on the traction / braking characteristics:

[0038] ;

[0039] b. Motion state calculation:

[0040] Calculate the actual acceleration:

[0041] ;

[0042] Calculate the final velocity of the step, which will also serve as the initial velocity for the next step. Here, we are actually solving for the starting velocity of this step, which will be used as the final velocity of the previous step.

[0043] ;

[0044] Calculate the step-size average velocity:

[0045] ;

[0046] Calculate the step size running time:

[0047] ;

[0048] Calculate step size consumption / recovery power:

[0049] ;

[0050] Calculate step size energy consumption / recovery:

[0051] ;

[0052] The third step involves combining forward calculation and braking back calculation to form a complete calculation method:

[0053] Based on the forward calculation process, a calculation symbol k is introduced, which is 1 during forward calculation and -1 during braking back calculation. Equations (1-1) and (2-1) are then combined into:

[0054] ;

[0055] Equations (1-2) and (2-2) can be combined and rewritten as follows:

[0056] ;

[0057] The rest of the calculation process remains unchanged, and the braking starting point can be calculated in one go, avoiding the use of trial and error to calculate the braking starting point, and the calculation process is very accurate;

[0058] Finally, calculate the cumulative running time:

[0059] ;

[0060] Calculate cumulative energy consumption:

[0061] .

[0062] The beneficial effects of this invention are as follows: This invention proposes a segmented cumulative train traction calculation method based on mileage, which can effectively avoid the trial-and-error process at each gradient change point in the analytical method, simplifying the calculation process. Furthermore, when the step size is set sufficiently small (e.g., 1m), the calculation process is highly accurate. For the braking process, since the braking start point and initial velocity are unknown, conventional forward calculation methods rely on trial and error. This invention proposes a braking back-calculation method that can complete the braking process in one operation, avoiding trial and error or nested loop solutions, simplifying the calculation process, and ensuring high accuracy. Attached Figure Description

[0063] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0064] Figure 1 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0065] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0066] This invention aims to provide a train traction calculation method. By proposing a segmented accumulation method based on mileage and a braking back calculation method, it avoids the trial-and-error process in traditional traction calculation methods, simplifies the calculation process, enhances applicability, and improves calculation accuracy.

[0067] In rail transit vehicle operation, the operating route, direction of travel, and stations are often fixed and completely deterministic, meaning the distance traveled by the vehicle during its journey is entirely predictable. Therefore, this invention proposes a segmented accumulation method based on mileage. This method divides the operating route into multiple steps for calculation, which can be fixed step lengths such as 1 meter or other segmentation methods. It assumes that the vehicle's acceleration remains constant within each calculation step. Based on the principles of mechanics, the forces acting on the vehicle are analyzed, and the vehicle's motion state is calculated. When the step length is set sufficiently small (e.g., 1 meter), the calculation accuracy can be considered sufficiently high.

[0068] In addition, when calculating braking needs to be performed, such as when the speed limit is reduced on a road section or when stopping at a station, a braking back calculation method is proposed. Based on the calculation results calculated in the forward direction according to the above method, the braking force and resistance are used as the driving force to accelerate backward from the braking endpoint until the speed reaches the speed of a previously calculated point and gradually covers the original motion state. This method can solve the braking starting point in one go without trial and error, and ensure that the vehicle speed is reduced to the speed limit or 0 at the braking endpoint.

[0069] like Figure 1 As shown, the specific technical solution for the train traction computerization method is as follows:

[0070] Step 1: Forward calculation, based on the segmented accumulation method of mileage:

[0071] a: Enter characteristic data. This part of the data is generally the inherent characteristics of the vehicle and the line. Before calculating the vehicle's operating status, it is necessary to enter parameters such as vehicle mass, traction / braking characteristics, and resistance characteristics, as well as parameters such as line length (including stations and stop times), gradient, and curve radius.

[0072] b: Set simulation parameters. These can be modified for each simulation. Pre-set the calculation step size (e.g., a fixed interval of 1m or other forms), target velocity, and initial simulation velocity, i.e., the step size interval ΔS and the target velocity v. aim Known.

[0073] c: Driver model, which simulates the driver's actions and calculates the traction / braking force of the vehicle at each step. There are many ways a driver can operate the vehicle, and many factors can be considered; a specific model is beyond the scope of this invention. This invention uses a driver model that "travels at the target speed as much as possible."

[0074] First, calculate the target acceleration:

[0075] ;

[0076] Calculate the target traction / braking force based on the target acceleration (traction is positive, braking force is negative):

[0077] ;

[0078] Among them, resistance is positive when it is opposite to the direction of train travel, and negative when it is the same as the direction of train travel.

[0079] Calculate the actual traction / braking force based on the traction / braking characteristics:

[0080] ;

[0081] d: Solve. Knowing the traction / braking force in this step, and assuming that the vehicle is undergoing uniform acceleration in each step, the vehicle's motion state can be solved based on the principles of mechanics.

[0082] Calculate the actual acceleration:

[0083] ;

[0084] Calculate the final velocity of the step length, and use it as the initial velocity for the next step length calculation:

[0085] ;

[0086] Calculate the average speed over the step:

[0087] ;

[0088] Calculate the step size running time:

[0089] ;

[0090] Calculate step size consumption / recovery power:

[0091] ;

[0092] Calculate step size consumption / recovery energy:

[0093] ;

[0094] e: Repeat steps 3 and 4 to solve the problem in a positive loop until the end of the route.

[0095] Step 2: Reverse calculation, accelerating backwards from the braking endpoint to perform a braking recalculation:

[0096] The target speed can be followed through the first part. It is a cumulative method based on mileage intervals. When the interval is small enough, the calculation accuracy is very high. It does not require trial calculation of the final speed at the change of slope. The calculation results are accurate and the calculation process is simplified.

[0097] However, in actual simulations, setting a reasonable target speed for each step is difficult. Often, the simulation interval is divided into several segments to set the target speed. Therefore, when the target speed decreases or even drops to 0 (stopping at a station), the above method cannot brake in advance, leading to speeding or missing the station. In other words, if a train is traveling at 100 km / h and the target speed ahead changes to 80 km / h or even 0 (stopping), the driver should brake in advance. If the driver waits until reaching the segment where the target speed changes before slowing down, the train will speed or miss the station.

[0098] In braking process calculations, determining the braking initiation point and initial braking velocity is crucial. Existing analytical methods employ trial-and-error approaches, which are complex and prone to errors. If a forward approach is used, assuming a braking initiation point and gradually advancing it until the speed limit is reached before the braking endpoint, thus covering the motion state of the braking process, this method is similar to the trial-and-error method. It requires nested loops in programming, resulting in high time complexity and inherent errors; that is, it cannot guarantee that the speed limit will be reached at the braking endpoint.

[0099] This invention proposes a braking back calculation method. After the forward calculation is completed, the train is directly set to reach the target speed at the braking endpoint. That is, the target speed is used as the initial speed of the simulation, and the braking force and resistance are used as the driving force. The train accelerates back from the braking endpoint until the speed reaches the speed corresponding to a certain step in the forward calculation. The calculation results of time, speed, power, energy, etc. from this step to the braking endpoint are covered by the calculation results of the braking back calculation.

[0100] The specific process is as follows:

[0101] a: Solving for braking force:

[0102] First, calculate the target acceleration:

[0103] ;

[0104] Although the calculation method starts from the braking endpoint and accelerates backward, it is actually a deceleration and braking process, so the previous step is multiplied by -1.

[0105] Calculate the target braking force based on the target acceleration:

[0106] ;

[0107] Calculate the actual braking force based on the traction / braking characteristics:

[0108] ;

[0109] b: Motion state calculation:

[0110] Calculate the actual acceleration:

[0111] ;

[0112] Calculate the final velocity of the step length, and use it as the initial velocity for the next step length calculation:

[0113] ;

[0114] What is actually being solved here is the starting velocity of this step, which is used as the ending velocity of the previous step.

[0115] Calculate the step-size average velocity:

[0116] ;

[0117] Calculate the step size running time:

[0118] ;

[0119] Calculate step size consumption / recovery power:

[0120] ;

[0121] Calculate step size energy consumption / recovery:

[0122] .

[0123] Step 3: The combination of forward calculation and braking back calculation forms a complete calculation method, which is easy to implement in programming:

[0124] It can be seen that the calculation process of forward calculation and braking back calculation is basically the same, with only slight differences between equations (1-1) and (2-1), and between equations (1-2) and (2-2).

[0125] Simply introduce a calculation symbol k into the forward calculation process, which is 1 during forward calculation and -1 during braking back calculation, and combine equations (1-1) and (2-1) into:

[0126] ;

[0127] Equations (1-2) and (2-2) can be combined and rewritten as follows:

[0128] ;

[0129] The rest of the calculation process remains unchanged, and the braking starting point can be calculated in one go, avoiding the need to use trial and error to calculate the braking starting point, and the calculation process is very accurate.

[0130] Finally, calculate the cumulative running time:

[0131] ;

[0132] Calculate cumulative energy consumption:

[0133] ;

[0134] Combining forward calculation and braking back calculation, the complete calculation method implementation process is as follows:

[0135] 1. First, enter parameters such as vehicle mass, traction / braking characteristics, and resistance characteristics, as well as calculation conditions such as line length (including stations and stop times), gradient, and curve radius.

[0136] 2. Set the length interval ΔS for each step (e.g., a fixed interval of 1m or other forms) and the line speed limit / target speed v. aim Define array variables of traction / braking force, acceleration, power, etc., with a length equal to the total number of steps.

[0137] 3. First, perform forward calculations. Calculate the target acceleration and target traction / braking force, and then, based on the traction / braking characteristics, calculate the actual acceleration and actual traction / braking force.

[0138] 4. Based on mechanical theory, calculate the terminal velocity, running time, power consumption / recovery, and energy consumption / recovery for each step.

[0139] 5. When the calculation reaches a point where the train speed is greater than the target speed, set the current speed as the line speed limit / target speed, use braking force and resistance as the driving force, and take the current point as the braking endpoint. Accelerate back and calculate until the speed reaches a point before braking. The calculation results of the back calculation process will directly overwrite the previous results.

[0140] 6. Starting from the point where the previous calculation was interrupted and the calculation started again, continue the forward calculation. If the same situation as in step 5 is encountered, repeat step 5 and consider the dwell time after entering the station based on the pre-set route station information until the end of the route.

[0141] 7. Based on the calculation results of each step, calculate the cumulative running time, cumulative energy consumption, etc.

[0142] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A train traction calculation method, characterized by, The method comprises: First step, the forward calculation based on the mileage-based segmented cumulative method: a. Before the vehicle running state, input the parameters of vehicle mass, traction / braking characteristics, resistance characteristics, and the parameters of running line length, slope on running line, curve radius on running line, and station, stopping time; b. Set the calculation step and target speed and the initial simulation speed in advance, i.e. the step interval ΔS and the target speed v aim ; c. Establish a driver model, that is, simulate the driver's operation to calculate the traction / braking force of the driver operating the vehicle at each step; First calculate the target acceleration: ； According to the target acceleration, calculate the target traction / braking force, the traction force is positive and the braking force is negative: , Wherein, the resistance is positive when it is opposite to the direction of train running, and negative when it is the same; According to the traction / braking characteristics, calculate the actual traction / braking force: ； d. Through the traction / braking force obtained in the third step, and assuming that the vehicle makes uniform acceleration motion at each step, the vehicle motion state can be solved according to the principle of mechanics: Calculate the actual acceleration: ； Calculate the step end speed, which is also the step initial speed for the next calculation: ； Calculate the step average speed: ； Calculate the step running time: ； Calculate the step consumption / recovery power: ； Calculate the step consumption / recovery energy: ； e. Repeat the third and fourth steps, and solve in a forward cycle until the end of the line; Second step, reverse calculation, accelerate back to brake back calculation at the braking end: a. Solve the braking force: First calculate the target acceleration: ； According to the target acceleration, calculate the target braking force: ； According to the traction / braking characteristics, calculate the actual braking force: ； b. Motion state solution: Calculate the actual acceleration: ； Calculate the step end speed, which is also the step initial speed for the next calculation, which actually solves the start speed of this step as the end speed of the previous step: ； Calculate the step average speed: ； Calculate the step running time: ； Calculate the step consumption / recovery power: ； Calculate the step consumption / recovery energy: ； Third step, combine the forward calculation and brake back calculation to form a complete calculation method: On the basis of the forward calculation process, introduce a calculation symbol k, which is 1 in forward calculation and-1 in brake back calculation, and combine formula (1-1) and formula (2-1) as: ； Formula (1-2) and formula (2-2) are combined and changed as: ； The rest of the calculation process remains the same, that is, the brake start point can be solved at one time, avoiding the use of trial and error method to solve the brake start point, and the calculation process is very accurate; Finally, calculate the cumulative running time: ； Calculate the cumulative energy consumption: 。

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