An Electric Bus Scheduling Method Considering the Influence of Charging and Train Formation Simultaneously

Abstract

The present invention discloses an electric bus scheduling method that simultaneously considers the influence of charging and platooning. First, parameters related to passengers and the driving state of electric buses are input to determine the conditional parameters for electric buses to drive towards the charging station. Secondly, vehicle charging prerequisite constraints and vehicle charging scheduling constraints are established, allowing vehicles to drive towards the charging station for charging at different intermediate stops, and calculating the optimal charging time for each vehicle. Finally, according to the station residence time, inter-station driving time, and electric bus charging time, the headway between adjacent vehicles at each station is calculated, and a model for optimizing the headway is established to alleviate the platooning phenomenon of vehicles on the same bus line, thereby obtaining an electric bus charging scheduling plan. By reasonably allocating the charging of electric buses at intermediate stops, the present invention solves the charging task of electric buses while alleviating the platooning phenomenon of urban bus lines and increasing the attractiveness of the urban bus system to passengers.

Description

Technical Field

[0001] The present invention belongs to the field of intelligent transportation, relates to the technical field of dynamic scheduling of urban bus lines, and more specifically, relates to an electric bus scheduling method that simultaneously considers the influence of charging and platooning. Background Art

[0002] During the operation of the bus system, it is usually disturbed by random factors. Existing research has shown that even very small disturbances (such as the driving behavior of drivers and special passenger demands, etc.), if not controlled, will deviate from the timetable in a short time. Over time, the headway and interval of buses will become irregular and eventually "cluster" together, resulting in the phenomenon of bus platooning. This phenomenon not only disrupts the arrival pattern of the bus timetable, but also, due to reasons such as passengers waiting too long at a certain stop or the passengers in the vehicle being too crowded, brings a poor travel experience to passengers and reduces the attractiveness of buses to passengers.

[0003] Therefore, the present invention proposes an electric bus scheduling method that simultaneously considers the influence of charging and platooning. For a conventional bus line that has already experienced platooning, this article allows electric buses to charge at intermediate stops. Different charging stations, charging times, and the residence time of vehicles at stations can affect the headway of vehicles. How to optimize the headway to alleviate the platooning phenomenon and at the same time determine the charging scheduling plan for electric buses at intermediate stops is the key problem to be solved in this patent.

[0004] Through the literature search of the prior art, it is found that when solving the problem of platooning of traditional buses, most of the literature adopts methods such as station stop, skip stop, and speed guidance. At present, there is no method to solve the platooning problem of electric buses by means of real-time charging scheduling and charging time control for the characteristics of electric buses that need to be charged. Summary of the Invention

[0005] Technical Problem: Aiming at the deficiencies of existing research, the purpose of the present invention is to provide an electric bus scheduling method that simultaneously considers the influence of charging and platooning. First, it judges whether the vehicle needs to be charged through the remaining power of the electric bus, conducts charging scheduling and charging time control for the charging vehicles at intermediate stops, and then calculates the headway of the electric bus arriving at each station. By optimizing the headway between vehicles, the charging scheduling plan of the electric bus is obtained.

[0006] Technical Solution: To solve the above technical problem, an electric bus scheduling method based on charging at intermediate stops to alleviate platooning of the present invention includes the following steps:

[0007] Step 1: Input parameters related to passengers, including the average arrival rate of passengers at each stop of the bus line and the average boarding time per passenger, and input parameters related to the driving state of the electric bus, including the departure frequency and headway at the initial moment of the electric bus, the average driving speed, and the distance between adjacent stops, and determine the condition parameters for the electric bus to drive to the charging station, including the remaining electric energy at the first stop, the electric energy required to complete the remaining journey of this line, the minimum charging time of the electric bus, and the maximum charging time;

[0008] Step 2: Establish the premise constraint for vehicle charging, compare the remaining electric energy of the electric bus at the first stop with the electric energy required to complete the remaining journey of this line, judge whether the electric bus needs to go to charge, establish the vehicle charging scheduling constraint, allow the vehicle to drive to the charging station for charging at different intermediate stops, and calculate the optimal charging time for each vehicle;

[0009] Step 3: Calculate the residence time of each vehicle at each stop through the passenger arrival rate and the average boarding time per passenger at each stop, calculate the headway between adjacent vehicles at each stop according to the stop residence time, the driving time between stops, and the charging time of the electric bus, and establish a model for optimizing the headway by performing real-time charging scheduling and charging time control for all buses at the intermediate stops to alleviate the phenomenon of vehicle bunching on the same bus line.

[0010] In the present invention, Step 1 includes the following steps:

[0011] Input the average arrival rate of passengers at each stop of the bus line and the average boarding time per passenger: Let S max represent the number of stops on this line, and number each stop starting from 1, then each stop s can be expressed as s ∈ {1, 2,..., S max}; Let ρ s represent the average arrival rate of passengers at stop s; Let t ave represent the average boarding time per passenger; Input parameters related to the driving state of the electric bus, including: Let N represent the departure frequency of the electric bus, number the vehicles according to the order of arrival, then each vehicle n can be expressed as n ∈ {1, 2,..., N}, let t n,1 represent the departure time of vehicle n at stop 1, in minutes; Let v represent the average driving speed of the vehicle, in km / h, let d s represent the distance between stop 1 and stop s, in km; Determine the condition parameters for the electric bus to drive to the charging station, including: Let represent the remaining electric energy of vehicle n at stop 1, in kwh, let q r represent the electric energy required to complete the remaining journey of this line, in kwh, let t p,min represent the minimum charging time of the electric bus, in minutes, let t p,maxIndicates the maximum charging time of the electric bus, with the unit of min;

[0012] In the present invention, step 2 establishes the charging prerequisite constraints and charging scheduling constraints for the electric bus, including the following steps:

[0013] Step 21: Establish the vehicle charging prerequisite constraints. Compare the remaining power of the electric bus at the first station with the power required to complete the remaining journey of the line, and determine whether the electric bus needs to go for charging, as shown in formula (1):

[0014]

[0015] In formula (1), Indicates whether vehicle n is driving to the charging station for charging at station s, Indicates that vehicle n is driving to the charging station for charging at station s, otherwise q r Indicates the energy required for the electric bus to drive from station 1 to station S max with the unit of kwh; Q max Indicates the battery capacity of the bus, with the unit of kwh, Indicates the remaining power of the electric bus at the first station, with the unit of kwh;

[0016] Step 22: Establish the vehicle charging scheduling constraints. Allow the vehicle to drive to the charging station for charging at different intermediate stations, and calculate the optimal charging time for each vehicle, as shown in formulas (2)-(3):

[0017]

[0018] In formula (3), use t p,n To indicate the charging time of vehicle n, with the unit of min; use t p,min To indicate the minimum charging time of the electric bus, with the unit of min; use t p,max To indicate the maximum charging time of the electric bus, with the unit of min;

[0019] In the present invention, step 3 calculates the headway between adjacent vehicles at each station and establishes the headway optimization model, including the following steps:

[0020] Step 31: Calculate the residence time of each vehicle at each station through the passenger arrival rate and the average arrival rate of unit passengers at each station. Use d n,s To indicate the residence time of the nth vehicle at station s, with the unit of min, as shown in formula (4); d 1,s To indicate the residence time of the first vehicle at station s, with the unit of min, d n,1 To indicate the residence time of the nth vehicle at station 1, with the unit of min, d 1,s And d n,1The value is a fixed constant, denoted by C, with the unit of min, as shown in formula (5):

[0021]

[0022] d 1,s = C, d n,1 = C, 2 ≤ s ≤ S max (5)

[0023] In formula (4), Δt n,s represents the headway between the nth vehicle and the (n - 1)th vehicle at station s, with the unit of min;

[0024] Step 32: Calculate the arrival time of the vehicle at each station based on the station dwell time, the running time between stations, and the charging time of the electric bus. Let A n,s represent the arrival time of vehicle n at station s, with the unit of min, and let M represent a very large positive number, as shown in formulas (6)-(9):

[0025]

[0026] where x n,s is an auxiliary variable. x n,s = 1 indicates that the vehicle does not leave the charging station midway before arriving at station n, otherwise it indicates leaving the charging station midway. In formulas (8) and (9), let t n,1 represent the departure time of vehicle n at station 1, with the unit of min; t p,n represent the charging time of vehicle n, with the unit of min;

[0027] Step 33: Calculate the departure time of the vehicle from each station based on the station dwell time, the running time between stations, and the charging time of the electric bus. Let B n,s represent the departure time of vehicle n from station s, with the unit of min, as shown in formula (10):

[0028]

[0029] Step 34: Calculate the headway between adjacent vehicles at each station. Let Δt n,s represent the headway between the nth vehicle and the (n - 1)th vehicle at station s, with the unit of min, as shown in formulas (11)-(12); calculate the average headway, denoted by ΔT ave represent, with the unit of min, as shown in formula (13):

[0030]

[0031] Step 35: Establish the constraint that two vehicles cannot appear at the same station simultaneously, as shown in formula (14):

[0032]

[0033] Step 36: Establish a model for optimizing the headway to alleviate the phenomenon of bunching of vehicles on the same bus line. The objective function is shown in Formula (15):

[0034]

[0035] In Formula (15), C total represents the total cost of the model, in yuan; C1 represents the unit deviation cost of the actual headway from the theoretical departure interval, in yuan / min²; C2 represents the unit deviation cost of the actual headway from the average headway, in yuan / min²; α represents the weight; T represents the length of the research period, in min.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] The method of the present invention aims at the phenomenon of bunching of vehicles on urban bus lines. By optimizing the headway, two vehicles will not appear at the same station simultaneously, and the headway is made as uniform as possible to alleviate the bunching phenomenon. At the same time, a charging and dispatching scheme for electric buses at intermediate stations is obtained, and the vehicles can complete the charging task. This increases the attractiveness of the urban bus system to passengers and promotes the electrification process of urban buses. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is the overall flow chart of the present invention;

[0039] Figure 2 is a schematic diagram of the charging and dispatching scheme for electric buses. DETAILED DESCRIPTION OF THE INVENTION

[0040] The following will, with reference to the appended Figure 1-2 drawings and embodiments, describe the present invention in further detail, but the embodiments of the present invention are not limited thereto. The embodiments of the present invention are not limited by the above examples. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

[0041] Embodiment 1

[0042] Select the No. 20 bus line in Tianxin District, Changsha City for research, and select the intermediate S max = 12 stations as the research object, as shown in the appended Figure 2 drawings; all the buses on this route are electric buses. The research time range T = 60 min, the departure frequency N = 8 vehicles / h, the average driving speed of the electric bus v = 20 km / h, and the average boarding time of each passenger t ave= 4.8 seconds per person, minimum charging time t p,min = 2 min, maximum charging time t p,max = 6 min, electrical energy q required for the vehicle to complete the remaining journey of this route r = 40.86 kwh, residence time d of the first vehicle at station s 1,s = C = 1 min, residence time d of the nth vehicle at station 1 n,1 = C = 1 min. The vehicle can drive to the charging station for charging at any intermediate station. At the charging station, the battery replacement strategy is adopted to fully charge the electric bus; the unit offset cost C1 between the actual headway and the theoretical departure interval is 10 yuan / min 2 , the unit offset cost C2 between the actual headway and the average headway is 10 yuan / min 2 , weight α = 0.5; distance d from station 1 to each intermediate station s , average passenger arrival rate ρ at each station s , remaining electrical energy of vehicle n at the first station Arrival time t of vehicle n at station 1 n,1 As shown in Table 1

[0043] Table 1: Parameter description table of Route 20 bus line

[0044]

[0045]

[0046] Example 2

[0047] According to Steps 2, Steps 3, formulas (1)-(14) and the objective function formula (15), the optimal charging scheduling plan for the intermediate stations of Route 20 bus line in Changsha is calculated, as shown in the appendix Figure 2 and Table 2. At the same time, the headway between two adjacent vehicles at each station on this route is obtained, and the results are shown in Table 3

[0048] Table 2: Optimal charging scheduling plan for intermediate stations

[0049] Vehicle number n 1 2 3 4 5 6 7 8 Charging station s 4 4 2 4 5 2 - 2 <![CDATA[Charging time t p,n (min)]]> 6 5.1 6 2.3 2 6 0 6

[0050] Table 3: Headway between adjacent stations

[0051]

[0052] Applying the method of the present invention, the value of the objective function T is 8322.77 yuan

Claims

1. An electric bus scheduling method that simultaneously considers the impacts of charging and car stringing, characterized in that The method includes the following steps: Step 1: Input the average arrival rate of passengers at each stop of the bus line and the average boarding time per passenger: Let S max represent the number of stops on the line. Number each stop starting from 1. Then each stop s can be expressed as s ∈ {1, 2, …, S max}; Let ρ s represent the average arrival rate of passengers at stop s; Let t ave represent the average boarding time per passenger; Input the parameters related to the driving state of an electric bus, including: the departure frequency of the electric bus is denoted by N. The buses are numbered according to the order of arrival, so each bus n can be expressed as n ∈ {1, 2, …, N}, and t n,1 represents the departure time of bus n at station 1, with the unit of min; v represents the average driving speed of the bus, with the unit of km / h, and d s represents the distance between station 1 and station s, with the unit of km; determine the condition parameters for the electric bus to drive to the charging station, including: represents the remaining power of bus n at station 1, with the unit of kwh, and q r represents the electric energy required to complete the remaining journey of this line, with the unit of kwh, and t p,min represents the minimum charging time of the electric bus, with the unit of min, and t p,max represents the maximum charging time of the electric bus, with the unit of min; Step 2: Establish the pre-conditions for vehicle charging. Compare the remaining power of the electric bus at the first stop with the power required to complete the remaining journey of the line to determine whether the electric bus needs to charge. Establish the vehicle charging scheduling constraints, allowing the vehicle to drive to the charging station for charging at different intermediate stops, and calculate the optimal charging time for each vehicle; Step 3: Calculate the dwell time of each vehicle at each stop based on the passenger arrival rate and the average boarding time per passenger at each stop. According to the stop dwell time, the travel time between stops, and the charging time of the electric bus, calculate the headway between adjacent vehicles at each stop. By performing real-time charging scheduling and charging time control for all buses at intermediate stops, establish a model to optimize the headway and alleviate the phenomenon of vehicle bunching on the same bus line; Step 3 mentioned above includes the following steps: Step 31: Calculate the dwell time of each vehicle at each station based on the passenger arrival rate and the average arrival rate per passenger at each station. Denote the dwell time of the nth vehicle at station s as d, in minutes, as shown in the following formula: n,s where d represents the dwell time of the nth vehicle at station s, in minutes, as shown in the following formula: where, Δt n,s represents the headway between the nth vehicle and the (n - 1)th vehicle at station s, with the unit of min; d 1,s represents the dwell time of the first vehicle at station s, in minutes, d n,1 represents the dwell time of the nth vehicle at station 1, in minutes, d 1,s and d n,1 The value of is a fixed constant, denoted by C, in minutes, as shown in the following formula: d 1,s = C, d n,1 = C, 2 ≤ s ≤ S max Step 32: Calculate the time when the vehicle arrives at each stop based on the stop residence time, the travel time between stops, and the charging time of the electric bus. Denote the time when vehicle n arrives at stop s as A, in minutes, and use M to represent a very large positive number. The formula is as follows: n,s where A is the time when vehicle n arrives at stop s, in minutes, and M is a very large positive number. The formula is as follows: where x n,s is an auxiliary variable, and x n,s = 1 indicates that vehicle n does not leave the charging process midway before arriving at station n, and vice versa indicates leaving the charging process midway; t n,1 represents the departure time of vehicle n at station 1, in minutes; t p,n represents the charging time of vehicle n, in minutes; is a binary variable, indicating that vehicle n leaves the line at station s and goes to the charging station for charging, otherwise Step 33: Calculate the time when the vehicle leaves each station based on the residence time at the station, the travel time between stations, and the charging time of the electric bus. Denote the time when vehicle n leaves station s as B, in minutes, as shown in the following formula: n,s The time when vehicle n leaves station s is denoted as B, in minutes, as shown in the following formula: Step 34: Calculate the time headway between adjacent vehicles at each station, denoted by Δt n,s which represents the time headway between the nth vehicle and the (n - 1)th vehicle at station s, in minutes, as shown in the following formula: Calculate the average headway, denoted by ΔT avg in minutes, as shown in the following formula: Step 35: Establish the constraint that two vehicles cannot appear at the same stop simultaneously, as shown in the following formula: Step 36: Establish a model to optimize the headway and alleviate the phenomenon of vehicle bunching on the same bus line. The objective function is as shown in the following formula: Among them, C total represents the total cost of the model, in yuan; C1 represents the unit offset cost of the actual headway and the theoretical headway interval, in yuan / min 2 ; C2 represents the unit offset cost of the actual headway and the average headway, in yuan / min 2 ; α represents the weight; T represents the length of the research period, in min 2. The electric bus scheduling method that simultaneously considers the influence of charging and car stringing according to claim 1, wherein, Step 2 mentioned above includes the following steps: Step 2 mentioned above includes the following steps: Step 21: Establish the pre-conditions for vehicle charging. Compare the remaining power of the electric bus at the first stop with the power required to complete the remaining journey of the line to determine whether the electric bus needs to charge, as shown in the following formula: Among them, indicates whether vehicle n drives to the charging station for charging at station s, indicates that vehicle n drives to the charging station for charging at station s, otherwise q r represents the energy required for the electric bus to drive from station 1 to station S max in kwh; Q max represents the battery capacity of the bus in kwh, represents the remaining power of the electric bus at the first station in kwh; Step 22: Establish the vehicle charging scheduling constraints, allowing the vehicle to drive to the charging station for charging at different intermediate stops, and calculate the optimal charging time for each vehicle, as shown in the following formula: Among them, t p,n represents the charging time of vehicle n, with the unit of min; t p,min represents the minimum charging time of the electric bus, with the unit of min; t p,max represents the maximum charging time of the electric bus, with the unit of min.

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