A few days ago, the China Automobile Association announced that from January to November 2017, the production and sales of new energy vehicles had completed 639,000 and 609,000 vehicles, respectively, an increase of 49.7% and 51.4% year-on-year respectively. By the end of November, the number of new energy vehicles in China reached 16.99 million. From the point of view of coordinated development of the entire industry chain, in the field of charging infrastructure, China currently has a total of approximately 195,000 public charging piles, plus the number of private charging piles, and the total ratio of the piles is approximately 4:1. Meet the normal charging needs of new energy vehicles.
Although the construction of charging facilities needs to be further strengthened, after nearly two years of turbulent and rapid advancement, the charging facilities industry has become increasingly rational. The special caller, Dexiang Chairman, pointed out at a forum that the “one vehicle and one vehicle†route was wrong. In the future, we must build a smart, environmentally-friendly, controllable charging and replacement network system. The author deeply believes that how to build a highly efficient and rationally distributed, fully-used centralized charging station or charging and replacement network system is particularly important. It is particularly recommended here to say that the new charging station construction model - the micro-grid energy storage system electric vehicle charging and discharging station (hereinafter referred to as the storage charge and discharge station).
What is energy storage charge and discharge station
The energy storage charge and discharge station is mainly composed of a storage energy charge and discharge module and a control system. The energy storage charge and discharge module realizes the energy conversion between the energy storage battery, the electric vehicle battery and the AC grid or the photovoltaic DC microgrid, and the control system realizes the battery Online monitoring management and control of energy storage charge and discharge modules. In a container-type cabinet, a battery pack, a storage and charge-discharge module, a corresponding control system, and a configuration of a charging control system are combined to form an electric vehicle charge-discharge storage system. The system adopts a modular design, and the maximum charge and discharge power and storage capacity can be adjusted according to the demand by increasing or decreasing the charge and discharge module and the battery capacity to meet the requirements of various different application scenarios.
In fact, this is also a smart microgrid system, which focuses on energy storage and forms a controllable, environmentally friendly and economical charging and discharging network. Without changing the distribution network, the system can achieve: the grid charging of electric vehicles; Energy storage; energy storage batteries are used to charge electric vehicles; energy storage batteries are sold to the grid; and electric vehicles sell electricity to the power grid. Form an ecological microgrid charge and discharge system.
Make full use of peak-valley electricity price difference
With the development of social economy, the contradiction between electricity supply and demand becomes more prominent. The electricity consumption changes greatly in the 24 hours a day. However, in order to cope with the peak demand during the day, the power supply plant designs the production scale or power supply capacity according to the demand of peak hours. In the off-peak hours, some devices are parked idle. Therefore, the marginal cost of power supply during peak hours is higher, and the marginal cost during non-peak hours is lower, thus forming the difference between the peak and the valley of power consumption. In order to balance the power supply and reduce the cost of the power plant, the grid company implements the peak-to-valley price.
The price difference between the peaks and valleys provides space for profit and cost savings for the implementation of electric energy storage. Mr. Shi, who has long devoted himself to the study of energy storage charging stations, calculated an account for the author, taking Shenzhen as an example:
The general industrial and commercial electricity charges in Shenzhen are: peak 1.0766 yuan/KW ̇H, valley 0.2801 yuan/KW ̇H.
It is assumed that electricity is used at a charging station during the peak period of 1000 degrees. Then
Ordinary charging station: 1000*1.0766=1076.6 yuan
Energy storage charging station: 1000*0.2801=280.1 yuan
“The charging station can then use electric vehicle charging and discharging and the microgrid energy storage system can save more than 73% of the electricity cost. The price difference between different provinces is not necessarily the same, but overall it can save more than 50-60% of the cost.â€
It can be seen that the price difference between peaks and valleys has a great impact on charging and operating companies. The energy storage charging station can just store the electricity in the trough time and use it to charge the electric vehicles during peak hours. This can not only meet the needs of the grid to balance supply, cut peaks and fill valleys, but also make full use of the peak-to-valley power price difference and save costs. increase profit.
Crack the power distribution network expansion problem
With the rapid growth of electric vehicles, the continuous increase in grid load will inevitably affect the efficiency of grid operation. The increase in distribution equipment capacity will involve the construction of substations, line construction, multi-sector coordination and complex construction and other issues. The huge cost and slow progress will not be conducive to the promotion and popularization of electric vehicles.
Li Xiangjun, a professor and senior engineer at the China Electric Power Academy, said that if energy is stored at night and stored energy is used during the day, this optimal scheduling can suppress peak-to-valley differences and greatly reduce network losses. The conversion of electricity from the grid through energy storage systems can reduce the burden on the national grid by up to 80%. As a result, communities, commercial districts, and even industrial districts can safely and reliably build charging stations to meet the growing demand for electric vehicle charging in the event that the distribution network capacity is insufficient.
Optical storage and charging integration
As of the first half of 17 years, the installed capacity of photovoltaic power generation in China reached 101.82 million kilowatts, including: photovoltaic power station 83.43 million kilowatts, distributed photovoltaic 17.43 million kilowatts, and national photovoltaic power generation 51.8 billion kwh, an increase of 75% year-on-year. Clean new energy power should be used to charge green and environmentally friendly electric vehicles, and it can also be the main way to eliminate abandoned light and wind power resources. The light storage mode has always been the focus of discussion in the industry. At present, there are a few examples of integrated charging stations in China.
Distributed photovoltaic is particularly suitable for combination with charging stations. Distributed energy has exceeded 100% this year. PV is built on the roofs of business parks, industrial parks, commercial residential buildings, etc. This large-scale photovoltaic construction generates enough energy. Satisfy the use of charging stations and form a micro-grid system independently. It is the best choice for those who have no grid qualification for private capital or individual enterprises, especially for new energy logistics vehicles and electric car rental companies that have centralized charging requirements, because distributed photovoltaic energy storage charging stations do not require large-area land stations. There is also no grid access problem, "power generation at the site, local consumption." At the same time, according to the needs of intelligent interaction with the public power grid, to achieve two different operating modes of grid-connected and off-grid; even participate in the auxiliary services such as peaking and frequency adjustment of the public power grid, peak-shaving and valley-filling. "In the future, the integration of 'light storage' can even be used as an intelligent high-speed supporting facility to support the 'three-network convergence' of smart road networks, smart grids, and intelligent information networks."
Retired Power Battery Echelon Utilization
The first batch of decommissioning peaks for domestic power batteries is approaching, with 1 million electric vehicles estimated. One car is equipped with 20 kw/h batteries, and in the future there will be 20 GW/h lithium-ion batteries in operation. If we can re-use lithium-ion power batteries that have been decommissioned for a second time and build a low-cost energy storage system, we can not only achieve good economic benefits through peak-to-valley spreads, but also avoid environmental damage and waste of resources and achieve good social benefits. With the construction of large-scale charging piles and the integration of energy storage charging stations, it not only helps to further reduce the construction cost, but also makes the electric vehicle-power battery-energy storage-photovoltaic-charging station, the five-in-one A greener and more virtuous cycle.
to sum up
Micro-grid energy storage system electric vehicle charging and discharging station, through the profit margin of the peak-to-valley spread, under the current capacity of the grid, do a good job of peaking and frequency modulation, ease pressure on transmission and distribution expansion, to maximize the balance of electricity, to the maximum The stability of the power grid is guaranteed, and it can be combined with new energy power, energy storage and optimized configuration can be used to balance the local energy production with the power load, and electricity can also be sold to the power grid; therefore, energy storage systems and electric vehicle charging must be considered together. The joint planning of station and distribution network surplus capacity and distributed photovoltaic new energy can not only satisfy the charging requirements, but also improve the economical efficiency, applicability and reliability of the implementation of the plan. It will surely become the main choice for future electric vehicle charging mode.
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