Disclosure of Invention
The technical purpose is as follows: in order to overcome the defects in the prior art, the invention provides a residential electric vehicle charging demand modeling method based on fuzzy comprehensive evaluation, which fully considers the influence of the residual charge state and the queuing waiting time on the vehicle owner charging selection behavior, calculates a one-day charging load curve of a residential area by using a Monte Carlo simulation method, and provides a reliable basis for safe and stable operation of a future power distribution network and reasonable layout of charging facilities.
The technical scheme is as follows: in order to achieve the technical purpose, the invention adopts the following technical scheme:
a modeling method for residential electric vehicle charging demand based on a fuzzy comprehensive evaluation method is characterized by comprising the following steps:
s1, establishing a power battery charging model of the single electric automobile;
s2, establishing a probability model of the time of arrival at the residential area and the daily mileage of each electric automobile;
s3, establishing a charging selection model based on a fuzzy comprehensive evaluation method;
and S4, calculating the charging requirement of each vehicle owner based on the Monte Carlo method.
2. The modeling method of electric vehicle charging demand for residential areas based on the fuzzy comprehensive evaluation method as set forth in claim 1, wherein in said step S4, the charging demand calculation step based on the monte carlo method is as follows:
s4.1, setting the maximum number N of the charging piles in the residential area, and generating a charging pile mark matrix S convenient for confirming the use condition of the charging pile:
wherein n represents the nth charging pile, and t represents time and unit minute;
s4.2, setting the number of the electric automobiles returning to the residential area within one day to be M, and acquiring vehicle information of the jth electric automobile at the return moment, including the residual electric quantity of the battery;
judging the occupation condition of a charging pile when the jth electric automobile arrives at the residential area, wherein the occupation condition comprises the condition that the charging pile is used for charging service and the condition that the charging automobile finishes the charging service but does not leave the parking space; judging whether redundant idle charging piles exist or not;
s4.3, simulating the charging willingness of the jth electric vehicle owner by using a fuzzy comprehensive evaluation method according to the charging selection model in the step S3;
if the jth charging automobile owner is willing to charge, a charging pile providing a charging service is distributed for the jth charging automobile, the corresponding element of the charging pile mark matrix is set to be 1, and if the jth electric automobile owner gives up charging, the corresponding element of the charging pile mark matrix is kept to be 0;
s4.4, calculating the charging time length T of the jth electric automobileC,j:
In the formula: t is t
wait,jTime for vehicle owner waiting for charging, t
ch,jThe length of service time for which charging is to be performed,
time to start charging for electric vehicle, t
arr,jTime to reach charging pile, SOC, for electric vehicle
tdIs a state of charge threshold, SOC
arr,jFor the jth electric vehicle to reach the state of charge, SOC, of the charging pile
exp,jDesired state of charge for jth electric vehicle, C
batThe battery capacity of the electric automobile is shown, eta is the charging efficiency, and lambda is the power decay time constant;
s4.5, simulating the behavior of the jth electric vehicle owner leaving the charging parking space by using a fuzzy comprehensive evaluation system according to the charging selection model in the step S3;
and if the jth charging car owner wants to approve moving the car at the moment of charging ending, setting the corresponding element of the charging pile mark matrix to be 0, otherwise, setting the corresponding element to be 1 until the next trip.
Preferably, in step S3, the method for establishing a charging selection model based on a fuzzy comprehensive evaluation method includes the steps of:
s3.1, determining an evaluation index system of charging selection, wherein the index system comprises a selectable factor set U;
s3.2, selecting an evaluation set V and a membership function mu (x);
s3.3, determining an evaluation factor weight vector W;
and S3.4, calculating a fuzzy relation matrix B for the fuzzy evaluation comprehensive evaluation method.
Preferably, in step S3.1, the evaluation index system includes a selectable factor set U, as shown in formula (4):
U={u1,u2} (4)
wherein u is1Is an SOC index, u2Is a queuing time index;
in the step S3.2, the electric vehicle owner charging selection evaluation result is divided into 3 levels, and the evaluation set is constructed as follows:
V={v1,v2,v3} (5)
in the formula: v. of1V for high willingness to charge2For general purpose of charging, v3The willingness to charge is low;
in step S3.2, a membership function is selected, specifically as follows:
aiming at SOC, selecting a trapezoidal distribution membership function model, and taking a smaller trapezoidal distribution as v1Distribution function of (d):
the middle type is distributed in a trapezoidal way as v2Distribution function of (d):
v is a large trapezoid3Distribution function of (d):
in the formula: a. b, c and d are fuzzy demarcation points of 3 evaluation grades respectively;
aiming at the queuing time, a ridge type distribution function model is selected, and a smaller ridge distribution is used as v1Distribution function of (d):
intermediate ridge distribution as v2Distribution function of (d):
partial large ridge distribution as v3Distribution function of (d):
in the formula a1、a2、a3、a4Fuzzy demarcation points of 3 evaluation grades respectively.
Preferably, in step S3.3, the evaluation factor weight vector is determined, and the specific steps are as follows:
after the SOC of the electric automobile arriving at the residential area and the queuing waiting time are definitely taken as main factors influencing a charging decision, a judgment matrix for comparing the two factors is constructed:
wherein a isij(i, j ═ 1, 2) is a proportional scale showing the ratio of the degree of influence of the two factors on the vehicle owner charging choice;
determining a relative weight vector by adopting a root finding method, wherein the formula is as follows:
i, j and k are the number of factors in an evaluation index system respectively, and the number of the factors is 1 and 2;
and (5) carrying out consistency check to verify the reasonability of the weight:
in the formula: CI is a consistency index, λmaxJudging the maximum eigenvalue of the matrix;
in the formula: RI is a random consistency index; CR is an index of the consistency ratio, and if CR <0.10, the consistency of the judgment matrix is considered to be acceptable.
Preferably, in step S3.4, the fuzzy relation matrix B is calculated as follows:
rmnrepresenting the degree of membership of the object to be evaluated to a certain evaluation factor, bnAnd represents the membership degree of the evaluated object to the evaluation result as a whole.
Preferably, the method further comprises the steps of:
s4.6, obtaining the waiting time, the charging time and the parking time of each electric vehicle in the parking lot of the whole residential area, wherein the total charging power W (t) of all the electric vehicles in the residential area is as follows:
wherein, PC,j(t) represents the charging power of the jth electric vehicle.
Preferably, in step S1, the power battery charging process of the electric vehicle includes a constant current stage and a constant voltage stage, and the formula of the power battery charging model is as follows:
wherein, PCFor charging electric vehicles, PmaxFor constant charging power in the constant-current phase, TtdAt the end of the constant current phase, TmAt the end of the constant voltage phase, λ is the power decay time constant, and t represents time.
Preferably, in the step S2, the arrival time of the vehicle owner at the residential area follows a normal distribution:
wherein, musAnd σsRespectively is the mean value and standard deviation of the time of the random variable returning to the residential area; x represents the time when the owner arrives at the residential area, fs(x) Indicating the arrival of the ownerA probability density function of time obeying of the residential area;
the daily mileage of the car owner follows lognormal distribution:
wherein, muDAnd σDRespectively is the mean value and standard deviation of the daily driving mileage of the random variable; f. ofD(x) And the probability density function represents the obedience of the daily mileage of the vehicle owner.
A residential electric vehicle charging system based on a fuzzy comprehensive evaluation method is characterized by comprising the following steps:
the monitoring data acquisition module is used for monitoring the entrance and exit conditions of the electric automobiles in the residential area and generating arrival time and departure time data, arrival charging pile time of each electric automobile, charging waiting time and charging duration data;
the database module is used for storing monitoring data and system data, wherein the system data comprises the number of charging piles of wind in a residential area, the number of electric vehicles in the residential area, the charge state threshold value of the electric vehicles and the battery capacity of the electric vehicles;
the data processing module executes the modeling method and is used for establishing a power battery charging model of a single electric vehicle according to system data and monitoring data, extracting the charging starting time and daily driving mileage of each electric vehicle by adopting a Monte Carlo method, establishing a probability model of the time of arriving at a residential area and the daily driving mileage of each electric vehicle, judging the charging selection of vehicle owners by utilizing a fuzzy comprehensive evaluation method, establishing a charging selection model based on the fuzzy comprehensive evaluation method, and analyzing to obtain the charging response time of each vehicle owner;
and the statistical analysis module is used for counting the daily charging behavior data of each vehicle owner, analyzing and obtaining the charging demand time distribution of each electric vehicle, and counting the daily load curve of the charging demand of the electric vehicles in the whole residential area.
Has the advantages that: due to the adoption of the technical scheme, the invention has the following technical effects:
the residential electric vehicle charging demand modeling method based on the fuzzy comprehensive judgment method provided by the invention considers the situation of insufficient charging facilities, and comprises two aspects, namely, early construction fails to consider the rapid increase of future electric vehicle reserves, and secondly, partial owners who finish charging service cannot leave a charging parking space in time to cause that the subsequent owners cannot carry out charging planning, and meanwhile, the charging demand modeling based on the charging willingness of the owners is carried out to carry out more refined modeling processing on the charging power of the electric vehicle, so that the residential charging demand is closer to the actual situation.
Detailed Description
As shown in fig. 1, the invention discloses a residential electric vehicle charging demand modeling method based on a fuzzy comprehensive judgment method.
Firstly, establishing a power battery model:
in the formula: pCFor charging electric vehicles, PmaxFor constant charging power in the constant-current phase, TtdAt the end of the constant current phase, TmAnd lambda is a power decay time constant at the end time of the constant voltage phase.
Secondly, establishing a probability model of the mileage of arriving at the residential area and traveling on the day:
the time of arrival of the owner at the residential area follows a normal distribution:
in the formula: mu.ssAnd σsRespectively, mean and standard deviation of the time for the vehicle owner to return to the residential area.
The daily mileage of the car owner follows lognormal distribution:
in the formula: mu.sDAnd σDThe average value and the standard deviation of the daily mileage of the electric automobile are respectively. f. ofD(x) And (3) representing a probability density function obeyed by the daily mileage of the vehicle owner, and establishing a data model of the daily mileage of the vehicle owner for extracting a random number obeying the probability density so as to accurately simulate the driving behavior of the vehicle owner.
Calculating the starting SOC of the jth electric automobile:
in the formula: d is the mileage on the day, dmThe maximum daily mileage.
Then, establishing a charging selection model based on a fuzzy comprehensive evaluation method:
when the owner judges the charging of the electric automobile which runs back to the residential area, the owner is restricted by various subjective and objective factors, and the subjective charging selection of the owner is reasonably judged by a fuzzy comprehensive evaluation method. The fuzzy comprehensive evaluation comprises the following specific steps:
(1) determining an evaluation index system of charging selection;
(2) selecting a comment set and a membership function;
(3) determining an evaluation factor weight vector;
(4) calculating a fuzzy relation matrix;
an evaluation index system of charging selection is determined, and the method comprises the following steps:
when the electric vehicle returns to the residence zone, the magnitude of the charge capacity (SOC) of the electric vehicle is directly related to whether the vehicle owner can continue the next journey, so the SOC is one of the factors influencing the charging selection of the vehicle owner. If the charging facility cannot meet all the car owners needing charging at a certain time, a queuing phenomenon occurs, and the length of the team is one of the factors directly influencing the charging selection of the car owners. The set of selectable factors is:
U={u1,u2}
in the formula u1Is an SOC index, u2Is a queuing time index.
Selecting a comment set:
the method comprises the following steps of dividing an electric vehicle owner charging selection evaluation result into 3 grades, wherein a constructed evaluation set is as follows:
V={υ1,υ2,υ3}
in the formula: upsilon is1Has high willingness to charge, upsilon2V is a general desire to charge3The willingness to charge is low.
Selecting a membership function:
aiming at SOC, selecting a trapezoidal distribution membership function model, and taking smaller trapezoidal distribution as upsilon1Distribution function of (d):
the middle type is in trapezoidal distribution as upsilon2Distribution function of (d):
slightly large trapezoidal distribution as upsilon3Distribution function of (d):
in the formula: a. b, c and d are fuzzy demarcation points of 3 evaluation grades respectively.
Aiming at queuing time, a ridge type distribution function model is selected, and smaller ridge distribution is used as upsilon1Distribution function of (d):
the middle ridge distribution as upsilon1Distribution function of (d):
partial large ridge distribution as upsilon1Distribution function of (d):
in the formula a1、a2、a3、a4Fuzzy demarcation points of 3 evaluation grades respectively.
Determining an evaluation factor weight vector:
after the SOC of the electric automobile arriving at the residential area and the queuing waiting time are definitely taken as main factors influencing a charging decision, a judgment matrix for comparing the two factors is constructed:
in the formula: a isij(i, j ═ 1, 2) is a proportional scale showing the ratio of the degree of influence of the two factors on the vehicle owner charging selection. Measuring the scale a by a ratio of 1-9ijSpecifically, the examples are shown in Table 1. Both Ci and Cj in table 1 are evaluation factors, referred to herein as electric vehicle SOC and queue waiting time to arrive at the residential area.
TABLE 1
Wherein Ci and Cj are the electric automobile SOC and the queue waiting time of the electric automobile arriving at the residential district respectively
Determining a relative weight vector by adopting a root finding method, wherein the formula is as follows:
and (5) carrying out consistency check to verify the reasonability of the weight:
in the formula: CI is a consistency index, λmaxThe maximum eigenvalue of the decision matrix.
In the formula: RI is a random consistency index, and is specifically shown in table 2.
TABLE 2
CR is an index of the consistency ratio, and if CR <0.10, the consistency of the judgment matrix is considered to be acceptable.
Calculating a fuzzy relation matrix, and multiplying the weight vector by the judgment matrix to obtain:
in the formula: r ismnRepresenting the degree of membership of the object to be evaluated to a certain evaluation factor, bnAnd represents the membership degree of the evaluated object to the evaluation result as a whole.
Charging demand calculations based on monte carlo. The method comprises the following steps:
1. the number N of the maximum charging piles in the residential area is set, and a charging pile mark matrix S convenient for confirming the use condition of the charging pile is generated:
2. setting the number of the electric automobiles returning to the community within one day as M;
3. acquiring all traffic information of the jth quantity of electric automobiles at the return moment, including the residual electric quantity of batteries and queuing waiting time;
4. and judging the occupation condition of the charging pile when the jth electric automobile arrives at the residential area, wherein the occupation condition comprises the condition that the charging pile is used for charging service and the condition that the charging automobile finishes the charging service but does not leave the parking space. Judging whether redundant idle charging piles exist or not;
5. simulating the charging willingness of the jth electric vehicle owner by using a fuzzy comprehensive evaluation method;
6. if the jth charging automobile owner is willing to charge, setting the corresponding element of the charging pile zone bit matrix for providing the charging service to the jth charging automobile owner to be 1, and if the jth electric automobile owner abandons the charging, keeping the corresponding element of the charging pile zone bit matrix to be 0;
7. calculating the charging time length T of the jth electric automobileC,j;
In the formula: t is t
wait,jTime for vehicle owner waiting for charging, t
ch,jThe length of service time for which charging is to be performed,
time to start charging for electric vehicle, t
arr,jTime to reach charging pile, SOC, for electric vehicle
tdIs a state of charge threshold, SOC
arr,jFor the ith electric vehicle to reach the state of charge, SOC of the charging pile
exp,jDesired state of charge for jth electric vehicle, C
batFor the battery capacity of the electric vehicle, different vehicles have different electricityThe pool capacity considers the respective battery capacity of different brand cars access charging piles, and the access charging piles can be identified and acquired by the charging piles. Eta is the charging efficiency, and lambda is the power decay time constant;
8. simulating the behavior of the jth electric automobile owner leaving the charging parking space by using a fuzzy comprehensive evaluation system;
9. if the jth charging automobile owner is willing to agree to move the automobile at the moment of charging ending, setting the corresponding element of the flag bit matrix to be 0, otherwise, setting the element to be 1 until the next trip;
10. and obtaining the waiting time, the charging time and the parking time of each electric automobile in the parking lot of the whole residential area. The charging total power w (t) of all electric vehicles in the residential area is shown in fig. 1 in a specific flow;
PC,j(t) represents the charging power of the jth electric vehicle.
The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.