A method for dispatching electric buses based on battery swapping for intermediate station charging

Abstract

The present invention discloses an electric bus dispatching method for charging at intermediate stations based on battery exchange. First, the passenger demand of each bus station is obtained through investigation, and various parameters related to the bus, the location of each charging station, the available backup battery of each charging station, and the service radius of each charging station are input; secondly, according to the passenger demand, the passenger demand loss cost and the fleet size cost are calculated; then, according to the charging station selection behavior of each vehicle, the vehicle intermediate station charging dispatching cost is calculated; finally, with the weighted sum of various costs as the minimum as the goal, the optimal fleet size and vehicle charging dispatching plan are calculated. The present invention can consider the travel benefits of passengers and the interests of bus operators at the same time by reasonably dispatching charging buses, solve the problem of insufficient mileage of electric buses, and promote the electrification process of urban buses.

Description

Technical Field

[0001] The present invention belongs to the field of intelligent transportation, and relates to the technical field of dynamic scheduling of urban bus lines, and more specifically, to an electric bus scheduling method based on battery exchange for charging at intermediate stations. Background Art

[0002] Electric buses have low pollutant emissions, low noise levels, and low maintenance and operating costs. They can eliminate local air pollution and significantly reduce greenhouse gas emissions. The electrification of bus fleets is the future development trend of public transportation. However, compared with traditional diesel buses, electric buses have "range anxiety" and need to be charged midway, as well as low efficiency in bus charging scheduling. How to determine the bus charging scheduling plan to improve vehicle charging efficiency is an issue that needs to be addressed urgently.

[0003] Therefore, the present invention proposes an electric bus scheduling method for charging at intermediate stations based on battery swapping. For a conventional bus line, several intermediate stations are arranged in sequence along the line. Each vehicle traveling on the line can enter the charging station at the intermediate station according to the energy consumption to complete the vehicle charging scheduling behavior. At the same time, in order to meet the short-term charging requirements of the intermediate station, the battery swapping mode is adopted to charge the vehicle. According to passenger demand, while taking into account the interests of passengers and bus operators, a function expression of passenger demand and fleet size is established. Finally, with the goal of minimizing the total system cost, determining the optimal charging scheduling plan for the charging station is the key problem to be solved by this patent.

[0004] After searching the literature on existing technologies, it was found that most of the literature requires electric buses to comply with the departure schedule and only allows vehicles to charge at the terminal stations. There are few literatures that study bus charging scheduling based on the actual needs of passengers. Currently, there is no research on charging scheduling models that take passenger needs into account and allow electric buses to enter charging stations at intermediate stations. Summary of the invention

[0005] Technical problem: In view of the shortcomings of existing research, the purpose of the present invention is to provide an electric bus scheduling method based on battery swapping for charging at intermediate stations. On the basis of considering passenger demand, a function expression of passenger demand and fleet size is established, the energy consumption of each vehicle is tracked, and each vehicle is allowed to charge at the intermediate station. With the goal of minimizing the total system cost, the optimal fleet size and vehicle charging scheduling plan are determined.

[0006] Technical solution: To solve the above technical problems, the present invention provides an electric bus dispatching method for charging at an intermediate station based on battery exchange, comprising the following steps:

[0007] Step 1: Obtain the passenger demand of each section of each bus line through investigation, input various parameters related to the bus, including the expected passenger capacity and battery capacity of the electric bus, input the parameters of each station on each bus line, including: the number of stations, the energy consumption value of the vehicle from the starting point to each intermediate station, the initial energy value of each vehicle at the starting point, the distance from each station to each charging station, determine the location of the charging station, the number of available backup batteries at each charging station during the study period, the service radius of each charging station, the unit electric bus cost, the unit charging adjustment cost, and the unit passenger loss cost;

[0008] Step 2: According to the size of passenger demand on each bus line, establish a functional expression between passenger demand and fleet size, and calculate the passenger demand loss cost and fleet size cost;

[0009] Step 3: Track the energy consumption of each vehicle on each bus route, calculate the energy consumption of each vehicle arriving at each station, establish a charging station selection model, and calculate the charging scheduling cost of the vehicle at the intermediate station;

[0010] Step 4: Based on the passenger demand on each route and the situation of each vehicle entering the charging station, the optimal fleet size and intermediate station charging scheduling plan are determined with the goal of minimizing the weighted sum of passenger demand loss cost, fleet size cost, and intermediate station charging scheduling cost.

[0011] In the present invention, step 1 comprises the following steps:

[0012] Through investigation, we can obtain the passenger demand between every two adjacent stops on each bus line, which includes the number of passengers getting on and off at each stop: i represents different bus lines, I represents the bus line set, i∈I; S i represents the set of adjacent bus stops on route i; (j, k) represents the adjacent bus stop section from j to k; represents the passenger demand for the (j, k) section on route i, in units of people; input various bus-related parameters, including: ave Indicates the average passenger capacity of the electric bus, in units of people / car; Q indicates the battery capacity of the electric bus, in units of kw·h; Input the parameters of each station on each route, including: i represents the maximum number of vehicles on each route; then each station k can be represented as k∈{1,2,…,K i};use It represents the cumulative energy consumption from the starting point to the intermediate station k on line i, in kw·h; represents the initial energy consumption at the starting point of line i, in kw·h; represents the distance from each station k to each charging station p on line i, in km; input various parameters related to the charging station, including: p represents the charging station, P represents the charging station set, p∈P; p max It represents the number of spare batteries available at charging station p, in blocks; R p represents the service radius of charging station p, in km; C1 represents the unit electric bus cost, in RMB / vehicle; C2 represents the unit line passenger demand loss cost, in RMB / (line·person); C3 represents the charging dispatch cost per unit distance and per unit energy consumption, in RMB / (km·kw·h);

[0013] In the present invention, step 2 calculates the passenger demand loss cost and the fleet size cost, including the following steps:

[0014] Step 21: Establish a functional expression between passenger demand and fleet size, and calculate the passenger demand loss of each line, as shown in formula (1):

[0015]

[0016] In formula (1), N i Represents the fleet size of each bus line, in units of vehicles, U i represents the number of lost passengers on bus line i, in units of people, represents the passenger demand for the (j, k) section on route i, in units of persons, η ave It represents the average passenger capacity of electric buses, in units of people / vehicle, K i Indicates the maximum number of vehicles on each route;

[0017] Step 22: Calculate the fleet size cost, C N represents the total cost of the bus fleet size of each bus route, in yuan, as shown in formula (2); calculate the passenger demand loss cost, C S It represents the total cost of passenger demand loss of each bus line, in yuan, as shown in formula (3):

[0018] C N =∑ i∈I C1N i (2)

[0019] C S =∑ i∈I C2U i (3)

[0020] In formula (2), C1 represents the unit bus cost, in RMB / vehicle; in formula (3), C2 represents the unit route passenger demand loss cost, in RMB / (route·person);

[0021] In the present invention, step 3 calculates the charging scheduling cost of the vehicle intermediate station, including the following steps:

[0022] Step 31: Charging must satisfy the service radius of the charging station, as shown in formula (4):

[0023]

[0024] In formula (4), is a binary variable, Indicates that the nth vehicle on route i enters charging station p at point k, otherwise it does not enter charging station p, R p is the service radius of charging station p, in km, is the distance from each station k to each charging station p on line i, in km;

[0025] Step 32: Track the energy consumption of each vehicle on each bus line, calculate the energy consumption of each vehicle when it arrives at each station, and establish a charging station selection model for each vehicle on each bus line at each station, as shown in formulas (5)-(6):

[0026]

[0027]

[0028] In formulas (5)-(6), δ represents the starting refueling rate, λ represents the safe driving ratio, represents the cumulative energy consumption from the starting point to the intermediate station k on line i, in kw·h. Indicates the route from the starting point to the intermediate station K on line i i The cumulative energy consumption is in kw·h; represents the initial energy consumption at the starting point of route i, in kw·h; Q represents the battery capacity of the electric bus, in kw·h; Formula (5) represents the energy consumption condition to be satisfied when selecting a charging vehicle; Formula (6) represents the energy consumption condition to be satisfied when not selecting a charging vehicle;

[0029] During the driving process, each bus on each bus line can complete a one-way trip of the bus with at most one charge, as shown in formula (7):

[0030]

[0031] Within the study time range T, the number of vehicles arriving at the charging station should not exceed the number of available backup batteries at the charging station, as shown in formula (8):

[0032]

[0033] In formula (8), pmax is the number of available backup batteries at charging station p, in blocks;

[0034] Step 33: Calculate the charging dispatch cost of the intermediate station, using C L It represents the total cost of charging dispatch at the intermediate station, in yuan, as shown in formula (9):

[0035]

[0036] In formula (9), C3 represents the charging scheduling cost per unit distance and unit energy consumption, in units of yuan / (km·kw·h);

[0037] In the present invention, step 4 comprises the following steps:

[0038] Step 4: Taking the weighted sum of passenger demand loss cost, fleet size cost, and charging scheduling cost as the minimum, determine the optimal fleet size and intermediate station charging scheduling plan. The objective function is shown in formula (10):

[0039] Minimize C=C N +C S +C L (10)

[0040] In formula (10), C represents the total cost of the model, in yuan.

[0041] Compared with the prior art, the present invention has the following advantages:

[0042] The method of the present invention aims at the charging scheduling problem of urban bus lines, considers the impact of passenger demand on the fleet size, determines the optimal fleet size, and calculates and obtains the optimal charging scheduling plan based on the charging selection plan of each vehicle at the charging station. The present invention considers the travel benefits of passengers and the interests of bus operators at the same time, reduces the total cost of the system, solves the problem of insufficient mileage of electric buses, and promotes the electrification process of urban buses. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is the overall flow chart of the present invention;

[0044] Figure 2 This is a schematic diagram of the location of the charging station;

[0045] Figure 3 Schematic diagram of charging scheduling scheme of an embodiment. DETAILED DESCRIPTION

[0046] The following is combined with Figure 1-3The present invention is further described in detail with reference to the accompanying drawings and embodiments, but the embodiments of the present invention are not limited thereto. The embodiments of the present invention are not limited by the examples described above, and 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 shall be included in the protection scope of the present invention.

[0047] Example 1

[0048] The 134 bus route in Tianxin District of Changsha was selected for research, and k = 11 stations in the middle were selected for research. All buses on this route are electric buses. The expected passenger capacity of electric buses is η ave =25 people / vehicle, battery capacity is η ave =200kw·h, the initial refueling rate is δ=0.5, and the safe driving ratio is λ=0.8; there are 4 charging stations along the route, and the service radius of charging station p is R p = 2.5km, the specific location diagram of the charging station is as attached Figure 2 As shown in the figure, the unit electric bus cost C1 is 20,000 yuan / vehicle, the unit line passenger demand loss cost C2 = 200 yuan / (line·person), and the charging scheduling cost per unit distance and unit energy consumption C3 is 10 yuan / (km·kw·h); the initial energy consumption value Randomly generate through normal distribution; survey to obtain the passenger demand of the (j, k) section on route i The cumulative energy consumption from the starting point to the intermediate station k on line i The locations of the charging stations are shown in Table 1 and the schematic diagram of the charging station locations is shown in the attached diagram. Figure 2 As shown; the distance from each station k to each charging station p on line i is obtained by investigation As shown in Table 2.

[0049] Table 1: Energy consumption and passenger demand at each stop on bus route 134

[0050]

[0051] Table 2: Distances from each bus stop k to each charging station p on bus route 134

[0052]

[0053] Example 2

[0054] According to step 2, step 3, step 4 (1)-(9) and objective function formula (10), the optimal fleet size and the optimal bus charging scheduling plan for Changsha No. 134 bus line are calculated. The fleet size on each line and the charging scheduling plan for each vehicle are shown in Table 3. The vehicle charging scheduling plan is shown in the attached figure. Figure 3 shown.

[0055] Table 3: Bus route 134 fleet size and charging scheduling plan

[0056]

[0057] Using the method of the present invention, the value of the objective function C is 63,000 yuan.

Claims

1. A method for dispatching electric buses based on battery exchange for charging at intermediate stations, characterized in that: The method comprises the following steps: Step 1: Through investigation, the passenger demand between every two adjacent stops on each bus line is obtained. The passenger demand includes the number of passengers getting on and off at each stop: i represents different bus lines, I represents the bus line set, i∈I; S i represents the set of road sections of adjacent bus stops on route i; (j, k) represents the road section corresponding to the adjacent bus stop from j to k; represents the passenger demand of the (j, k) section on route i, in units of persons; Input various bus-related parameters, including: ave Indicates the average passenger capacity of the electric bus in units of people / car; Q indicates the battery capacity of the electric bus in units of kWh·h; Input the parameters of each station on each bus line, including: i Indicates the maximum number of vehicles on each bus route; represents the cumulative energy consumption from the starting point to the intermediate station k on line i, in kWh·h; represents the initial energy consumption of the originating station on line i, in kWh·h; input various parameters related to the charging station, including: p represents the charging station, P represents the charging station set, p∈P; p max Indicates the number of spare rechargeable batteries in charging station p, in units of blocks; R p represents the service radius of charging station p, in km; C1 represents the unit electric bus cost, in RMB / vehicle; C2 represents the unit line passenger demand loss cost, in RMB / (line·person); C3 represents the charging dispatch cost per unit distance and per unit energy consumption, in RMB / (km·kwh); Step 2: According to the size of passenger demand on each bus line, establish a functional expression between passenger demand and fleet size, and calculate the passenger demand loss cost and fleet size cost; The step 2 comprises the following steps: Step 21: Establish a functional expression between passenger demand and fleet size, and calculate the passenger demand loss of each line, as shown in formula (1): In formula (1), N i Represents the fleet size of each bus line, in units of vehicles, U i Represents the number of lost passengers on the bus line, in units of people, represents the passenger demand of the section (j, k) on route i, in units of persons, η ave It represents the average passenger capacity of electric buses, in units of people / vehicle, K i Indicates the maximum number of vehicles on each route; Step 22: Calculate the fleet size cost, C N represents the total cost of the bus fleet size of each bus route, in yuan, as shown in formula (2); calculate the passenger demand loss cost, C S It represents the total cost of passenger demand loss of each bus line, in yuan, as shown in formula (3): C N =∑ i∈I C1N i (2) C S =∑ i∈I C2U i (3) In formula (2), C1 represents the unit cost of a single bus, in RMB / vehicle; in formula (3), C2 represents the unit cost of passenger demand loss per route, in RMB / (route·person); Step 3: Track the energy consumption of each vehicle on each bus route, calculate the energy consumption of each vehicle arriving at each station, establish a charging station selection model, and calculate the charging scheduling cost of the vehicle at the intermediate station; The step 3 comprises the following steps: Step 31: Charging must satisfy the service radius of the charging station, as shown in formula (4): In formula (4), is a binary variable, Indicates that the nth vehicle on route i enters charging station p at point k, otherwise it does not enter charging station p; R p is the service radius of the charging station, in km, is the distance from each station k to each charging station p on line i, in km; Step 32: Track the energy consumption of each vehicle on each bus line, calculate the energy consumption of each vehicle arriving at the station, and establish a charging station selection model for each vehicle on each bus line at each station, as shown in formulas (5)-(6): In formulas (5)-(6), δ represents the starting refueling rate, λ represents the safe driving ratio, represents the cumulative energy consumption from the starting point to the intermediate station k on line i, in kw·h; Indicates the route from the starting point to the intermediate station K on line i i The cumulative energy consumption, in kw·h; represents the initial energy consumption at the starting point of line i, in kw·h; Q represents the capacity of the electric bus, in kw·h; Formula (5) represents the energy condition that a charging vehicle must meet; Formula (6) represents the energy condition that a non-charging vehicle must meet; During the driving process, each bus on each bus line can complete a one-way trip of the bus with at most one charge, as shown in formula (7): Within the study time range T, the number of vehicles arriving at the charging station cannot exceed the number of backup batteries at the charging station, as shown in formula (8): In formula (8), p max is the number of spare batteries in charging station p, in blocks Step 33: Calculate the charging dispatch cost of the intermediate station, using C L represents the charging dispatch cost of the intermediate station, in yuan, as shown in formula (9): In formula (9), C3 represents the charging scheduling cost per unit distance energy consumption, in units of yuan / (km·kw·h); Step 4: Determine the optimal fleet size and intermediate station charging scheduling plan with the goal of minimizing the weighted sum of passenger demand loss cost, fleet size cost, and charging scheduling cost.

2. According to claim 1, a method for dispatching electric buses based on battery exchange for charging at intermediate stations is characterized in that: The step 4 comprises the following steps: Step 4: Taking the weighted sum of passenger demand loss cost, fleet size cost, and charging scheduling cost as the minimum, determine the optimal fleet size and intermediate station charging scheduling plan. The objective function is shown in formula (10): Minimize C=C N +C S +C L (10) In formula (10), C represents the total cost of the model, in yuan.

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