18650 rechargeable battery lithium 3.7v 3500mah

　　Research on the participation of power 18650 rechargeable battery lithium 3.7v 3500mahin power grid peak regulation

　　1 Overview

　　With the promotion and application of electric vehicles and the construction of charging stations, people's understanding of electric vehicles and charging stations is no longer limited to transportation tools and "gas stations", but they hope to develop a wider range of applications. Although most of the charging stations currently operating and under construction at home and abroad only have the single function of supplying energy to electric vehicles, the United States, Germany and other countries are already conducting research on V2G (Vehicle to Grid) related technologies.

　　V2G refers to the two-way exchange of energy and information between electric vehicles and the power grid as a mobile energy storage unit under controlled conditions. The electric vehicle (charging station) not only obtains energy from the power grid, but also realizes the transfer of energy to the power grid when necessary. The power grid sends electricity back, thereby improving the reliability of grid operation.

　　Electric vehicles containing distributed mobile energy storage units have the advantages of complementing the large power grid, alleviating the power supply shortage of the power grid, and improving the reliability of the power grid. With the development of technology, the mobile energy storage application of electric vehicle power 18650 rechargeable battery lithium 3.7v 3500mahcan further reduce the investment and operating costs of the power system. The combination of ultra-large power stations and decentralized micro power stations can reduce investment in transmission and distribution lines and improve the operation of the power system. safety and economy. In particular, compared with many distributed power sources, the biggest advantage of electric vehicle power battery mobile energy storage is that when a large-scale power outage occurs in a large power grid, the electric vehicle power battery mobile energy storage can still maintain normal operation, which can Improve the disaster resilience of power systems.

　　2V2G technology application advantages and feasibility

　　Overall, the peak-to-valley difference between major power grids is increasing day by day, and the contradiction between the power grid's peak-shaving capacity and the objective peak-shaving needs is very acute. V2G's participation in peak-shaving of the power system is extremely helpful in dealing with the increasingly serious peak-shaving problem. great significance.

　　2.1 Advantages of V2G technology application

　　(1) Adjusting the capacity can be guaranteed. 90% of electric vehicles can participate in V2G services 24 hours a day. Even during peak traffic periods, more than 80% of the vehicles are parked, and private electric vehicles are parked most of the time.

　　(2) Fast response speed. The charging and discharging of electric vehicles with bidirectional power adjustment function can reach ms level, while the traditional peaking power supply has to take into account the life of mechanical components, and the fastest response time is around s level.

　　(3) The response power reserve margin is small. The inaccurate response of traditional peak shaving and frequency modulation to AGC signals requires a larger response power reserve margin for power grid dispatching, while V2G responds quickly and accurately to peak shaving and frequency modulation commands, which can reduce the power reserve margin.

　　(4) High overall efficiency. The charging and discharging efficiency of the battery is higher than the average comprehensive energy efficiency of general pumped storage power station operation.

　　(5) It has obvious social and economic benefits. Electric vehicles can take advantage of off-peak power from the grid and provide services when the grid is at its peak.

　　2.2 Feasibility of V2G technology application

　　Electric vehicles/charging stations have a two-way power exchange function, which can either transmit power to the grid (i.e., the electric vehicle discharge state) or absorb power from the grid (i.e., the electric vehicle charging state); secondly, electric vehicles/charging stations have two-way communication functions , capable of receiving instructions and sending power information remotely. Peak shaving instructions are sent to electric vehicles by the grid dispatcher through the communication network in the charging station. The response of the electric vehicle is monitored, recorded and fed back to the charging station (backend management system) through the communication network. If electric vehicles develop to a certain scale and have relevant policy and technical support, peak shaving instructions can also be sent directly to electric vehicles through wireless communication, and the responses of electric vehicles can be monitored and recorded (the response results of each electric vehicle should also be fed back through wireless communication To the charging station background management system). Therefore, electric vehicles can achieve organized and planned peak shaving according to the requirements of the grid.

　　3 Basic ideas for realizing V2G peak shaving applications

　　According to the peak load regulation demand and the V2G statistical information of each charging station, the power grid formulates a V2G charging and discharging plan through relevant strategies and sends it to each charging station; after receiving the plan, each charging and discharging station rationally selects vehicles through relevant strategies and algorithms, and allocates charging Discharge power to ensure reasonable execution of charging and discharging plans. The schematic diagram of V2G participating in system peak shaving is shown in Figure 1.

　　4 Forecast of available capacity and available time

　　From the perspective of grid security, V2G, as a large number of distributed power generation units with user participation, connected to the system will inevitably have a certain impact on the operation of the grid. Therefore, accurately predicting various parameters of V2G in the dispatching process will surely become One of the issues that the power grid dispatching and operating agencies are concerned about. Precisely because V2G has two-way interaction with user energy, its available capacity prediction problem is more complex than traditional load prediction. From a technical analysis, the available capacity of V2G energy storage can be obtained in the following two ways.

　　(1) Adopt user setting method

　　It refers to the user setting up a plan for the vehicle to participate in V2G for the next week on a weekend. The V2G operator and the backend management center use this as a standard to calculate the V2G available capacity for the next week, and give priority to the planned part in the actual charging and discharging execution. This model is similar to the contract market and real-time market models in the power market, and has good promotion prospects.

　　(2) Using historical data for prediction

　　The capacity of V2G is closely related to weather, holidays, prices, temperatures, seasons, economic development, and the number of electric vehicles participating in V2G services. In the early stages of V2G service implementation, since there are relatively few participating vehicles, a peak-hour discharge model can be adopted. As the technology and market mature, the number of participating vehicles will gradually increase, and the historical data of V2G will gradually accumulate, so that various prediction methods can be used to predict available capacity, such as the regression analysis method, time series method, etc. commonly used in the current power system. Exponential smoothing method, gray model method, Kalman filter method and some artificial intelligence methods such as expert system, artificial neural network, fuzzy prediction and other methods.

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