System and Method for Controlling Charging and Discharging of Electric Vehicle

• US 20160159239A1
• Filed: 09/10/2014
• Published: 06/09/2016
• Est. Priority Date: 12/02/2013
• Status: Active Grant

• Current Assignee: State Grid Chongqing Power Co., Ltd., State Grid Corporation of China
• Original Assignee: State Grid Chongqing Power Co., Ltd., State Grid Corporation of China
• Inventors: Shi, Lefeng, Liu, Zhengfa, Hou, Xingzhe, Liu, Yongxiang, Gong, Lin, Wang, Huicai, Yang, Zewei
• Granted Patent: US 10,112,499 B2
• Time in Patent Office: Days
• CPC Class Codes: B60L 53/14 Conductive energy transfer
• CPC Class Codes: B60L 55/00 Arrangements for supplying energy stored within a vehicle to a power network, i.e. vehicle-to-grid [V2G] arrangements
• CPC Class Codes: H02J 13/00028 involving the use of Internet protocols
• CPC Class Codes: H02J 2310/48 for electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: H02J 3/322 the battery being on-board an electric or hybrid vehicle, e.g. vehicle to grid arrangements [V2G], power aggregation, use of the battery for network load balancing, coordinated or cooperative battery charging
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: Y02B 70/30 Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles
• CPC Class Codes: Y02T 90/167 Systems integrating technologies related to power network operation and communication or information technologies for supporting the interoperability of electric or hybrid vehicles, i.e. smartgrids as interface for battery charging of electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: Y04S 10/126 the energy generation units being or involving electric vehicles [EV] or hybrid vehicles [HEV], i.e. power aggregation of EV or HEV, vehicle to grid arrangements [V2G]
• CPC Class Codes: Y04S 10/14 Energy storage units
• CPC Class Codes: Y04S 20/221 General power management systems
• CPC Class Codes: Y04S 30/12 Remote or cooperative charging

Abstract

A method for controlling charging and discharging of an electric vehicle, the method comprising: first, analyzing information such as the battery status and the history default rate of electric vehicles applying for joining a power-grid charging and discharging service, and screening out an electric vehicle that can participate in the charging and discharging service for electric vehicles in the future; then, determining an optimal combination state of a generator set and the electric vehicle by using a method of electric energy transmission cost comparison; and further monitoring in real time the status of the electric vehicle during charging and discharging, and performing real-time power control on the electric vehicle, whereby an electric vehicle aggregator not only can meet the requirements on the charging and discharging service of the power system, but also can implement energy management and real-time control of the electric vehicles during charging and discharging, thereby reducing the effect of charging and discharging on the vehicle-mounted power battery.

Claims

1. A charging and discharging control system for an electric vehicle, characterized in that it includes a total control platform and a detecting module;

said total control platform including a communication module, a data storage and management module, a dual-level optimization control module, and a power distribution control module;

said communication module for achieving two-way interaction between the total control platform and the electric vehicle, transmitting requirements for a charging and discharging service to a user of the electric vehicle, transmitting the total control platform willingness of the electric vehicle to participate in the charging and discharging service and real-time data about battery status, and performing data transmission and communication with a power control module in a charger;

said data storage and management module for storing and managing data related to charging and discharging of the electric vehicle, assigning power command values about charging and discharging of the electric vehicle to related interface variables by protocol to be invoked by the total control platform;

said dual-level optimization control module for determining in real time start-stop and power output conditions of a generator set in a wide-area power system, computing in real time decision variables of charging and discharging power of the electric vehicle which participates in a grid charging and discharging service, determining a number of electric vehicles which participate in the charging and discharging service and a real-time charging and discharging power by integrating and analyzing decision variables and data of the generator set;

said power distribution control module for controlling the charging and discharging power of the electric vehicle after receiving power control commands from the communication module;

said detecting module for detecting in real time power battery state of the electric vehicle connected to the grid and sending detection data to the total control platform through the communication module.

2. A method for controlling charging and discharging of an electric vehicle, characterized in that it includes steps of:

Step 1;

reading in real time load conditions of each load point in a wide-area power system, analyzing electrical energy demand of the wide-area power system in a next period of time;

reading in real time related data of an electric vehicle which is willing to participate in a charging and discharging service of a power system, and storing and managing data through a data storage and management module;

Step 2;

determining a total cost of transfer of electrical energy from a generator set i to a wide area network during a period of time t;

Step 3;

determining a total cost of participation of an electric vehicle j in the charging and discharging service and screening out a dispatchable electric vehicle aggregator;

Step 4;

obtaining a combination of the generator set and the electric vehicle which participates in the charging and discharging service according to Step 2 and Step 3;

Step 5;

reading in real time data related to a power battery of the electric vehicle which participates in the charging and discharging service and calculating charging and discharging command values of the electric vehicle which participates in a grid charging and discharging service; and

Step 6;

storing and then outputting charging and discharging power commands of the electric vehicle which participates in the charging and discharging service.

3. The method for controlling charging and discharging of an electric vehicle as recited in claim 2, characterized in that in Step 1, the related data of the electric vehicle comprises:

default rates of an electric vehicle which participated in the charging and discharging service in the past, network topology points where the electric vehicle is connected to the power system, charging and discharging energy demand acceptable to the electric vehicle, rated power of a vehicle-mounted power battery of the electric vehicle, controllable status values, maximum allowable operating power scale values, charge state values, maximum allowable discharging power and maximum allowable charging power, wherein the maximum allowable discharging power and the maximum allowable charging power are both the maximum allowable operating power;

when the charging and discharging energy demand of the electric vehicle has a positive value, it indicates that the electric vehicle is willing to participate in a charging service, and at this time said maximum allowable operating power is the maximum allowable charging power;

and when the charging and discharging energy demand of the electric vehicle has a negative value, it indicates that the electric vehicle is willing to participate in a discharging service, and at this time said maximum allowable operating power is the maximum allowable charging power.

4. The method for controlling charging and discharging of an electric vehicle as recited in claim 2, characterized in that said Step 2 specifically includes substeps of:

Step 21;

monitoring in real time running status of the generator set and measuring whether the generator set i can participate in power dispatching in a future period of time t;

Step 22;

determining a fuel cost C_fi^g(p_i(t)) of the generator set i based on historical data on power generation efficiency and fuel cost of the generator set;

Step 23;

determining an emission cost C_ei^g(p_i(t)) of the generator set i based on historical data on carbon emission factor and carbon emission cost of the generator set;

Step 24;

measuring and dispatching network loss of electric quantity p_i(t) during the process of transmission through simulation of transmission from the generator set i to load points of wide area network, further calculating a cost of network loss C_li^g(p_i(t));

Step 25;

determining a total cost C_j^g(p_j(t)) of transmission of electrical energy from the generator set i to wide area network during the period of time t based on the fuel cost, emission cost, and network loss cost of the generator set, the total cost having functions of;

5. The method for controlling charging and discharging of an electric vehicle as recited in claim 2, characterized in that said Step 3 specifically includes substeps of:

Step 31;

determining whether the electric vehicle j is willing to participate in a charging and discharging service within the period of time t according to an application for the charging and discharging service when the electric vehicle is connected to the grid;

Step 32;

measuring a voluntary electricity price offered by the electric vehicle which is willing to participate in the charging and discharging service and determining a charging and discharging electrical quantity cost C_bj^v(p_j(t)) of the electric vehicle;

Step 33;

measuring and analyzing a probability P(E_j)P(Y_t|E_j) of possible unexpected events E_j and a resulting consequence s(Y_t) based on historical data when the electric vehicle j participates in the charging and discharging service, further calculating a risk cost C_hj^v(p_j(t)) resulting from participation of the electric vehicle in the charging and discharging service;

Step 34;

measuring network loss of electric quantity during the process of transmission through simulation of participation of the electric vehicle j in the charging and discharging, further calculating a network loss cost C_lj^v(p_j(t));

Step 35;

determining a total cost C_j^v(p_j(t)) caused by participation of the electric vehicle j in the charging and discharging service based on transaction cost, risk cost, and network loss cost of the electric vehicle j participating in the charging and discharging, the cost having functions of;

6. The method for controlling charging and discharging of an electric vehicle as recited in claim 2, characterized in that a combination of the generator set and a controllable electric vehicle in Step 4 has a target function of:

7. The method for controlling charging and discharging of an electric vehicle as recited in claim 2, characterized in that said Step 5 specifically includes steps of:

Step 51;

utilizing the charging and discharging power p_j(t) of the electric vehicle within the period of time t, and calculating a power command value of the electric vehicle which participates in the charging and discharging γ

_j based on a power demand for the electric vehicle aggregator by the power system and dynamic charge status of the vehicle-mounted power battery;