A bus fast-charging station orderly charging method considering dynamic charging energy efficiency

Abstract

The present application relates to the field of bus charging technology, in particular to a bus fast charging station orderly charging method considering dynamic charging energy efficiency; the method first determines the power demand meeting the operation of the bus line, then establishes the relationship between the charging energy conversion efficiency and the actual charging power of the vehicle-mounted energy storage system, takes the minimum actual power consumption of the charging station in a day or the minimum actual electricity cost of the charging station in a day as the objective function, establishes a nonlinear optimization objective function model, then converts the nonlinear optimization objective function model into a mixed integer convex programming problem, solves the mixed integer convex programming problem to obtain the optimal charging plan, including the optimal charging time and the corresponding charging power of each vehicle; the present scheme fully considers the relationship between the charging power and the transformer efficiency, the charger efficiency and the battery efficiency, improves the charging energy conversion efficiency of the electric bus, reduces the power consumption cost of the charging station operator and the charging cost of the electric bus, and improves the economy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bus charging, in particular to a bus fast charging station orderly charging method considering dynamic charging energy efficiency. BACKGROUND

[0002] As an important part of electric vehicles, electric buses have fixed charging locations compared with the randomness of private cars and taxis. For the same bus operation line, the running route and time are relatively fixed. The battery capacity and charging power of electric buses are much larger than those of electric private cars. One of the mainstream charging modes of electric buses is the fast charging mode of returning to the station with piles, that is, the quick charging mode. Large-scale disordered charging will have an adverse impact on the power grid, intensify the peak of the power grid, and also lead to the problem of over-planning of charging piles, increasing the construction cost and electricity cost of charging piles. In view of this problem, the research on the orderly charging of electric buses has become a hot spot. However, the current research on the orderly charging of electric vehicles is mainly based on time-of-use electricity price. The research based on time-of-use electricity price aims to reduce the charging cost of users and reduce the load peak-valley difference to guide electric vehicles to charge orderly, without considering the charging energy conversion efficiency.

[0003] In the invention patent application with the publication number CN111619394A, the use of electricity load data of each time period in the region is obtained from the power grid. The charging type of each electric bus is determined, including not accepting charging and discharging scheduling, accepting orderly charging scheduling, and accepting orderly charging and discharging scheduling. On the power grid side, the minimum load peak-valley difference is taken as the objective function. On the electric bus operator side, the minimum electric bus charging cost is taken as the objective function. An optimization model is established by taking the battery capacity, operation time, and charging and discharging power of the electric bus as the constraint condition, and the optimal charging and discharging time and power scheme is obtained by solving the model. However, the relationship between charging efficiency and transformer efficiency, charging machine efficiency, and battery efficiency is not considered in this scheme, resulting in waste of electric energy. SUMMARY

[0004] In view of the deficiencies in the prior art, the present application aims to provide an electric bus orderly charging method that fully considers the relationship between charging power and transformer efficiency, charging machine efficiency, and battery efficiency, which can further improve the energy conversion efficiency of charging on the basis of traditional orderly charging, reduce the electricity cost of charging station operators and the charging cost of electric buses, and improve the economic efficiency of the bus fast charging station orderly charging method considering dynamic charging energy efficiency.

[0005] To solve the above technical problems, the technical solution provided by the present application is: a bus fast charging station orderly charging method considering dynamic charging energy efficiency, which comprises the following steps:

[0006] S1: Determine the power demand that meets the operation of the bus line according to the operation time of the charging station, the equipment power limit, the quantity limit and the bus departure plan;

[0007] S2: Based on the energy flow topology of the charging process of the charging station, the relationship between the charging energy conversion efficiency and the actual charging power of the vehicle-mounted energy storage system is established by establishing transformer efficiency, charger efficiency and battery efficiency models;

[0008] S3: Taking the actual power consumption of the charging station in a day or the actual electricity cost of the charging station in a day as the objective function, considering the charging energy conversion efficiency, taking the electric bus line operation power demand and the continuity of the electric bus charging time as the constraint condition, a nonlinear optimization objective function model is established;

[0009] S4: The nonlinear optimization objective function model in step S3 is converted into a mixed integer convex programming problem by using piecewise linearization, and the optimal charging plan including the optimal charging time and the corresponding charging power of each vehicle is obtained by solving the mixed integer convex programming problem.

[0010] Further, in step S1, it is necessary to ensure that the state of charge of the vehicle-mounted energy storage system of all buses before the departure time can meet the complete line:

[0011]

[0012]

[0013] In the formula, j is the vehicle number; is the number of bus vehicles serving the line of vehicle j; is the first departure time, the last bus time and the departure interval of the line of vehicle j, respectively; j is the length of the line where vehicle j is located; n j is the number of times each bus in the line served by vehicle j needs to be repeated; is the starting time of vehicle j in the kth cycle; V j is the unit kilometer energy consumption of the line served by vehicle j; C p,j is the maximum energy of the vehicle-mounted energy storage system of vehicle j; soc low is the SOC safety lower limit considering the additional loss caused by traffic conditions to ensure safe operation of the vehicle; represents the SOC of vehicle j before the kth cycle departs.

[0014] Further, in step S2, the relationship between the charging energy conversion efficiency of transformer efficiency, charger efficiency, and battery efficiency and the actual charging power of the vehicle-mounted energy storage system is considered as:

[0015]

[0016] where t represents the time of charging, is the actual power consumed by the power distribution network; is the actual charging power of the vehicle-mounted energy storage system; is the output power of the charging pile; η hl is the efficiency of the transformer when reducing voltage; η ad is the charger efficiency; η b is the efficiency of the power battery in the vehicle-mounted energy storage system during charging;

[0017] The transformer efficiency model is established as:

[0018]

[0019] The charger efficiency model is established as:

[0020]

[0021] The battery efficiency model is established as:

[0022]

[0023] where m is the number of phases of the transformer, I2 is the current at the secondary side of the transformer, R k is the short-circuit resistance reduced to the secondary side, is the transformer power factor angle, is the transformer iron loss, U 20 is the no-load voltage at the secondary side of the transformer; is the output power of the charger, P F , P C , P sw are the forward conduction loss, reverse conduction loss, and switching loss of the IGBT in the charger, respectively; η b is the battery charging efficiency, U bat is the terminal voltage of the lithium battery, I bat is the charging current; R ser is the equivalent internal resistance of the battery.

[0024] Further, in step S3, the actual electricity consumption of the charging station in a day is taken as the objective function:

[0025]

[0026] In the formula, T represents the number of unit time divided in a day;△t is a unit time, in this paper△t=60s;J is the total number of vehicles served by the bus charging station; is the actual charging power of the jth vehicle at time t, is the output power of the charging pile when the jth vehicle is charging at time t; P t ch is the actual charging power P

[0027] Further, in step S3, the actual electricity cost of the charging station in a day is taken as the objective function:

[0028]

[0029] c(t) is the commercial electricity price of the charging station operation city at time t.

[0030] Further, in step S4, the constraint condition of the objective function is:

[0031] Time constraint:

[0032] The following formula indicates that the bus cannot be charged when it is not at the charging station:

[0033]

[0034] The following formula indicates that all vehicles cannot be charged when the charging station stops business:

[0035]

[0036] In the formula, d j,t is the charging state of vehicle j at time t, d j,t ∈{0,1}, d j,t =1 vehicle is in charging state, otherwise in non-charging state; is the set of time when the bus with number j is not at the charging station, wherein is the departure time of the jth vehicle in the kth round, is the back station time of the jth vehicle in the kth round, n j is the total number of rounds that vehicle j needs to circulate in a day; T close is the closing time of the charging station;

[0037] Charging station equipment constraint:

[0038] The following formula indicates that the number of charging piles simultaneously in charging is less than or equal to the total number of charging equipment N cs in the charging station:

[0039]

[0040] The following formula indicates that the maximum power of a single charging pile must not exceed the safe power P. cs ;

[0041]

[0042] The following formula indicates that the total power distribution capacity of the charging station must not exceed the maximum safe power P of the charging station's power distribution network. s :

[0043]

[0044] Constraints on travel demand:

[0045] The following formula indicates that the State of Charge (SOC) of each vehicle at the start of each cycle should be between the ratio of the energy required for a single trip to the maximum energy, plus the minimum SOC lower limit for the protection battery. low and the set maximum SOC (soc) max between:

[0046]

[0047] The following formula represents the departure time of vehicle j on the kth time. The formula for calculating the State of Charge (SOC) of a vehicle. The vehicle's SOC at any given time is the SOC at the beginning of the day plus the amount of electricity charged into the vehicle during previous charging activities, minus the electricity consumed during previous trips.

[0048]

[0049] The following formula represents the total amount of electricity charged in a day that can meet the daily travel needs, ensuring the cyclicality of the charging strategy:

[0050] The following formula shows that, using this charging strategy, the charging behavior of each bus is continuous over time:

[0051]

[0052]

[0053] In the formula, y j,t and z j,t y is the decision variable for controlling the start and end of continuous charging during the charging process of vehicle j after returning to the station. j,t , z j,t ∈{0,1}; This refers to the collection of time periods that vehicle j spends within the charging station after returning to the station.

[0054] Compared with existing technologies, this solution has the following significant advantages: it considers the relationship between charging power and transformer efficiency, charger efficiency, and battery efficiency, and uses the minimum actual electricity consumption in a day as the objective function, thereby improving the energy conversion efficiency of electric bus charging; while improving the charging energy conversion efficiency, it also improves the objective function, using the minimum actual electricity cost of the charging station in a day as the objective function, thereby reducing the electricity cost for charging station operators and the charging cost for electric buses. Attached Figure Description

[0055] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0056] Figure 1 This is a schematic diagram of the steps of the present invention;

[0057] Figure 2 This is a topology diagram of the energy flow in the charging station according to the present invention;

[0058] Figure 3 This refers to the Rint model. Detailed Implementation

[0059] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0060] like Figure 1 As shown, the orderly charging method for bus fast charging stations considering dynamic charging energy efficiency according to the present invention includes the following steps:

[0061] S1: Determine the electricity demand required to meet the operation of bus routes based on the charging station's operating time, equipment power limitations, quantity limitations, and bus departure schedule;

[0062] S2: Based on the energy flow topology of the charging process in the charging station, the relationship between the charging energy conversion efficiency and the actual charging power of the on-board energy storage system is established by establishing models of transformer efficiency, charger efficiency and battery efficiency.

[0063] S3: The objective function is to minimize the actual electricity consumption of the charging station in a day or to minimize the actual electricity cost of the charging station in a day. The nonlinear optimization objective function model is established with the charging energy conversion efficiency as a consideration and the power demand of the electric bus route and the continuity of the charging time of the electric bus as constraints.

[0064] S4: using piecewise linearization to convert the nonlinear optimization objective function model in step S3 into a mixed integer convex programming problem, and solving the mixed integer convex programming problem to obtain the optimal charging plan, including the optimal charging time and corresponding charging power of each vehicle.

[0065] Firstly, the bus charging station needs to meet the departure demand of multiple bus lines at the same time, and the travel demand of the bus line is determined by the departure table made by the operator. In the embodiment, the departure timetable of a certain bus station is provided, as shown in the following table:

[0066]

[0067] The application studies the charging demand of the electric bus, and ensures that the state of charge of the vehicle-mounted energy storage system of all buses can meet the energy consumption of walking a complete line before the departure time:

[0068]

[0069]

[0070] In the formula, j is the vehicle number; is the number of bus vehicles serving the line of vehicle j; is the first departure time, the last bus time and the departure interval of the line of vehicle j, respectively. j is the length of the running line of vehicle j; n j is the number of times each bus in the line served by vehicle j needs to run repeatedly; is the starting time of vehicle j in the kth cycle; V j is the unit kilometer energy consumption of the line served by vehicle j; C p,j is the maximum energy of the vehicle-mounted energy storage system of vehicle j; soc low is the SOC safety lower limit considering the additional loss caused by factors such as traffic conditions to ensure safe operation of the vehicle; represents the SOC of vehicle j before the kth cycle departs.

[0071] On this basis, as Figure 2 shown, the scheme establishes the relationship between the charging energy conversion efficiency and the actual charging power of the vehicle-mounted energy storage system. First, the efficiency model of each part in the charging process is established, including the transformer efficiency, charger efficiency and battery efficiency model. Then, according to the efficiency model of each part, the relationship between the charging energy conversion efficiency and the actual charging power of the vehicle-mounted energy storage system is established, which specifically includes the following steps:

[0072] S2.1: Transformer efficiency model establishment:

[0073] The losses generated in the actual operation of the transformer mainly include copper loss and iron loss. The copper loss of the transformer is proportional to the square of the load current. The iron loss mainly includes hysteresis loss and eddy current loss caused by the alternating main magnetic flux in the transformer core and some stray loss.

[0074] The total loss of the transformer is:

[0075]

[0076] In the formula, P loss is the total loss of the transformer, is the copper loss of the transformer, is the iron loss of the transformer, m is the number of phases of the transformer, I2 is the current at the secondary side of the transformer, R k is the short-circuit resistance reduced to the secondary side.

[0077] The input and output power relationship of the transformer is:

[0078]

[0079] In the formula is the input power of the transformer, is the output power of the transformer, U2, U 2N are the voltage at the secondary side of the transformer and the rated value of the voltage at the secondary side respectively, S N is the rated capacity of the transformer, is the per-unit value of the secondary side current, I 2N is the current rating at the secondary side of the transformer, is the power factor angle.

[0080] The ratio of the input side power to the output side power of the transformer is the efficiency η hl , η hl is related to the output power of the transformer:

[0081]

[0082] S2.2: Establishing the efficiency model of the charger:

[0083] The losses of the charger mainly include the conduction loss and switching loss of the IGBT. The conduction loss of the IGBT is related to the conduction resistance. In the working process, the forward conduction state and the reverse conduction state appear, and the forward conduction loss P F and the reverse conduction loss P C are respectively:

[0084]

[0085]

[0086] In the formula, T s is the working cycle of the device; i sf , i sc are the forward and reverse conduction currents of the device, respectively; R ds , R sd is the on-resistance when conducting in the forward and reverse directions, which changes with the current, temperature and driving voltage.

[0087] The switching loss of the IGBT is mainly related to the switching times N s of the device, and the switching loss is recorded as s

[0088]

[0089] In the formula, is the total switching energy loss of the device in the qth switching process, which is related to the voltage, current and temperature in the switching process, so the overall efficiency η ad of the charger is related to the output power of the charger:

[0090]

[0091] S2.3: Establishing a battery efficiency model:

[0092] First, an equivalent circuit model of the battery is established. The electric bus charging is constant current charging, and the polarization is established for a short time, so the polarization capacitance is not considered. The Rint model is selected to analyze the battery efficiency, as shown in Figure 3 The model can be represented by the following formula:

[0093] U bat = I bat · R ser + U ocv

[0094] In the formula, U bat is the terminal voltage of the lithium battery; U ocv is the open circuit voltage of the battery; I bat is the charging current; and R ser is the equivalent internal resistance of the battery.

[0095] The efficiency η b of the battery charging process is calculated by the following formula:

[0096]

[0097] P t ch ​The actual charging power supplied to the onboard energy storage system can be expressed as the battery's open-circuit voltage U. ocv and battery charging current I bat The product of; the present invention applies to η b The following derivation and simplification yield η b The actual charging power P of the on-board energy storage system t ch Relationship:

[0098]

[0099] S2.4: The relationship between the charging energy conversion efficiency, considering transformer efficiency, charger efficiency, and battery efficiency, and the actual charging power of the on-board energy storage system can be expressed as:

[0100]

[0101] In the formula, t represents the charging time, and P t g P represents the actual power consumed by the distribution network. t ch The actual charging power supplied to the on-board energy storage system; P t pile The output power of the charging pile; η hl Efficiency when reducing voltage in a transformer; η ad For charger efficiency; η b This refers to the efficiency of the power battery in an on-board energy storage system during the charging process.

[0102] Based on the relationship between transformer efficiency, charger efficiency and their respective output power, and the relationship between battery efficiency and the actual charging power of the on-board energy storage system, the above formula can be expressed as:

[0103]

[0104] The daily electricity requirement of an electric bus charging station can be determined by the electric bus schedule, and can be expressed as:

[0105]

[0106] The daily electricity requirement is determined by the departure schedule and the route length. The daily energy conversion efficiency η of the charging station can be expressed as:

[0107]

[0108] In the formula C ostg This represents the actual electricity consumption of the charging station during the day.

[0109] According to the above formula, the charging station energy conversion efficiency is the highest, which is equivalent to the minimum actual power consumption, and thus equivalent to the minimum actual power consumption of the charging station in a day as the objective function under the premise of considering the charging energy conversion efficiency.

[0110] In order to reflect the influence of the dynamic charging energy efficiency of the bus fast charging station ordered charging method, the embodiment compares four different scenarios:

[0111] Scenario one: without using any scheduling strategy, the bus charges as soon as it arrives at the station;

[0112] Scenario two: ordered charging with the minimum power consumption as the target, the objective function is:

[0113]

[0114] In the formula, T represents the number of unit time divided in a day;△t is the unit time, in this paper△t=60s;J is the total number of vehicles served by the bus charging station;P t ch Pj(t) is the actual charging power of the jth vehicle at t time of the vehicle-mounted energy storage system, P t pile Pj(t) is the output power of the charging pile when the jth vehicle charges at t time.

[0115] Scenario three: with the minimum daily operating electricity fee as the target, considering the energy conversion efficiency of electric vehicles, the objective function is:

[0116]

[0117] In the formula, c(t) is the commercial electricity price of the charging station operating city at t time.

[0118] Scenario four: with the minimum daily operating electricity fee as the target, without considering the charging energy conversion efficiency of electric buses, P t g Pj(t) = P t pile Pj(t) = P t ch The objective function is:

[0119]

[0120] The constraints required by the above optimization problem are as follows:

[0121] S3.1: Time constraints:

[0122] The following formula indicates that the bus cannot charge when it is not at the charging station:

[0123]

[0124] The following formula represents that all vehicles cannot be charged when the charging station stops business:

[0125]

[0126] In the formula, d j,t is the state of charge of vehicle j at time t, d j,t ∈{0, 1}, d j,t = 1 vehicle is in the charging state, otherwise in the non-charging state; is the time set in which the bus numbered j is not at the charging station, wherein is the departure time of the kth round of vehicle j, is the back station time of the kth round of vehicle j, n j is the total number of rounds that vehicle j needs to circulate in a day; T close is the time when the charging station is closed.

[0127] S3.2: Charging station equipment constraints:

[0128] The following formula represents that the number of charging piles simultaneously in charging is less than or equal to the total number of charging equipment in the charging station N cs :

[0129]

[0130] The following formula represents that the maximum power of a single charging pile cannot exceed the safe power P cs :

[0131]

[0132] The following formula represents that the power distribution capacity of the entire charging station cannot exceed the maximum safe power P s of the charging station power distribution network:

[0133]

[0134] S.3: Constraints on travel demand:

[0135] The following formula represents that the SOC of each vehicle at the departure time of each round should be between the ratio of the energy required for a single trip to the maximum energy plus the lower limit of the SOC soc low of the protection battery and the set maximum SOC soc max :

[0136]

[0137] The following formula represents the calculation formula of the SOC of vehicle j at the kth departure time : SOC of the vehicle at the moment is the SOC at the beginning of the day plus the amount of electricity charged into the vehicle before this moment, minus the amount of electricity consumed before the trip:

[0138]

[0139] The following formula indicates that the amount of electricity charged in a day can meet the sum of the required electricity for a day, ensuring the recyclability of the charging strategy:

[0140] The following formula shows that the charging behavior of each bus in the time scale is continuous using the charging strategy:

[0141]

[0142]

[0143] In the formula, y j,t and z j,t are the starting and ending decision variables of the continuous charging process of the vehicle numbered j after returning to the station, y j,t , z j,t ∈{0,1}; is the set of time periods of vehicle j in the charging station after returning to the station,

[0144] A further improvement of the scheme is that since the established transformer efficiency model, charger efficiency model and battery efficiency model exhibit nonlinear characteristics, the optimization objective established in step S3 is nonlinear optimization. The scheme uses piecewise linearization for processing, and the formula for piecewise linearization is:

[0145]

[0146]

[0147]

[0148]

[0149] In the formula, is an auxiliary constraint parameter, subscript x corresponds to the xth segment after linearization, represents that the charging power is located in the xth segment of the broken line segment after piecewise linearization, and the value is and are the upper and lower limit values of the xth segment of the segmented interval power P li,x ; K η,x and B η,x are linearization coefficients, reflecting the influence of charging power ; Wx = {1,2,3}.

[0150] Finally, the optimization objective obtained by the above steps is a mixed integer convex programming problem, and the optimal charging plan, including the optimal charging time and the corresponding charging power P t ch and the corresponding P t pile The results show that the power consumption of scenario two is reduced compared to scenario one, and the cost of scenario three is lower than that of scenario four. Through the comparison results, it can be known that the ordered charging method of the bus fast-charging station considering the dynamic charging energy conversion efficiency can reduce the power consumption, that is, improve the charging energy conversion efficiency, and at the same time reduce the power consumption cost of the charging station operator and the charging cost of the electric bus.

[0151] Finally, it should be noted that the above only describes the preferred examples of the present application and does not limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for orderly charging of a bus fast-charging station taking into account dynamic charging energy efficiency, characterized in that, The method comprises the following steps: S1: determining the power demand of the bus line operation according to the operation time of the charging station, the equipment power limit, the quantity limit and the bus departure plan; S2: based on the energy flow topology of the charging process of the charging station, the relationship between the charging energy conversion efficiency and the actual charging power of the vehicle-mounted energy storage system is established by establishing transformer efficiency, charger efficiency and battery efficiency models; S3: taking the minimum actual power consumption of the charging station in a day or the minimum actual electricity cost of the charging station in a day as the objective function, wherein the charging energy conversion efficiency is considered, the nonlinear optimization objective function model is established with the bus line operation power demand, the continuity of the electric bus charging time as the constraint condition; S4: the nonlinear optimization objective function model in step S3 is converted into a mixed integer convex programming problem by using piecewise linearization, and the optimal charging plan including the optimal charging time and the corresponding charging power of each vehicle is obtained by solving the mixed integer convex programming problem.

2. The method of claim 1, wherein the method further comprises: In step S1, it is necessary to ensure that the state of charge of the vehicle-mounted energy storage system before the departure time of all buses can meet the complete line route: where j is the vehicle number; the number of buses serving the route for vehicle j; the first departure time, the last departure time and the departure interval of the route for vehicle j, respectively; j the length of the route for vehicle j; j the number of times each bus needs to repeat the route for vehicle j; the start time of the kth cycle for vehicle j; j the energy consumption per kilometer for the route for vehicle j; p,j the maximum energy of the energy storage system for vehicle j; low the lower limit of the SOC for the safety of the vehicle, considering the additional loss caused by the traffic conditions; the SOC of vehicle j before the kth cycle.

3. The method of claim 1, wherein the method further comprises: In step S2, the relationship between the charging energy conversion efficiency of transformer efficiency, charger efficiency and battery efficiency and the actual charging power of the vehicle-mounted energy storage system is: where t represents the time of charging, P t g P is the actual consumed power of the distribution network; P t ch P is the actual charging power of the vehicle-mounted energy storage system; P t pile P is the output power of the charging pile; η hl P is the efficiency of the transformer when reducing voltage; η ad P is the efficiency of the charger; η b P is the efficiency of the power battery in the vehicle-mounted energy storage system during charging. The transformer efficiency model is established as: The charger efficiency model is established as: The battery efficiency model is established as: where m is the phase number of the transformer, I2 is the current at the secondary side of the transformer, R k is the short-circuit resistance reduced to the secondary side, is the power factor angle of the transformer, is the iron loss of the transformer, U 20 is the no-load voltage at the secondary side of the transformer; is the output power of the charger, P F , P C , P sw are the forward conduction loss, the reverse conduction loss and the switching loss of the IGBT in the charger, respectively; η b U is the terminal voltage of the battery bat U is the terminal voltage of the lithium battery bat I is the charging current; R ser R is the equivalent internal resistance of the battery.

4. The method of claim 1, wherein the method further comprises: In step S3, the minimum actual power consumption of the charging station in a day is taken as the objective function: In the formula, T represents the number of unit time divided in a day;△t is the unit time, and in this paper,△t=60s; J is the total number of vehicles served by the bus charging station; Pj(t) is the actual charging power of the jth vehicle at time t; Pj(t) is the output power of the charging pile when the jth vehicle is charging at time t; Pj(t) is the actual charging power of the jth vehicle at time t; t ch ηj(t) is the transformer efficiency, charger efficiency, and battery efficiency corresponding to the actual charging power Pj(t) at time t.

5. The method of claim 1, wherein the method further comprises: In step S3, the minimum actual electricity cost of the charging station in a day is taken as the objective function: c(t) is the commercial electricity price of the charging station operation city t.

6. The method for ordered charging of bus fast-charging stations taking into account dynamic charging energy efficiency according to any one of claims 4-5, characterized in that, In step S4, the constraint condition of the objective function is: Time constraint: The following formula indicates that the bus cannot be charged when it is not in the charging station: The following formula indicates that all vehicles cannot be charged when the charging station stops business: where d j,t is the state of charge of vehicle j at time t, d j,t ∈ {0, 1}, d j,t = 1 if the vehicle is in charging state, otherwise in non-charging state; is the set of time when bus number j is not at charging station, where is the departure time of vehicle j in the kth round, is the back time of vehicle j in the kth round, n j is the total number of rounds that vehicle j has to circulate in a day; T close is the time when charging station is closed; Charging station equipment constraint: The number of charging piles simultaneously in charging is less than or equal to the total number N of charging devices in the charging station cs : The maximum power of a single charging pile shall not exceed the safety power P cs ; The following formula indicates that the power distribution capacity of the entire charging station must not exceed the maximum safe power P of the power distribution network of the charging station s : Travel demand constraint: The following formula indicates that the SOC of the vehicle at the departure time of each cycle should be between the ratio of the energy required for a single trip and the maximum energy plus the lower SOC limit soc low and the set SOC maximum soc max : The formula below represents the vehicle j at the kth departure time The formula for calculating the vehicle SOC at the kth departure time, The SOC of the vehicle at the kth departure time is the SOC at the initial time of the day plus the amount of electricity charged into the vehicle before this time, minus the amount of electricity consumed before the trip. The following formula represents that the amount of electricity charged in a day can meet the sum of the required electric energy for a day's travel, ensuring the recyclability of the charging strategy: The following formula shows that the charging behavior of each bus in the time scale is continuous by using the charging strategy: where y j,t and z j,t are the start and end decision variables for controlling consecutive charging for vehicle j after returning to the station, y j,t , z j,t ∈{0,1}; is the set of time periods for vehicle j after returning to the station,

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