best value public electric car charging stations engineering technology

1. Communication mode of electric vehicle charging station (pile)

The electric vehicle charging station (pile) belongs to the distribution network side. Its communication mode is often considered together with distribution network automation. Communication is a key and difficult point of distribution network automation. Different regions and conditions have different communication modes that can be applied, specifically to the electric vehicle charging station (pile). Its communication modes mainly include wired mode and wireless mode.

1) Wired mode

(1) Wired Ethernet (RJ45 wire, optical fiber). The main advantages of wired Ethernet are reliable data transmission and large network capacity. The disadvantages are complex wiring, poor scalability, high construction cost and poor flexibility.

(2) Industrial serial bus (RS-485, RS-232, can bus). The advantages of industrial serial bus (RS-485, RS-232, can bus) are reliable data transmission and simple design. The disadvantages are complex network layout, poor expansibility, high construction cost, poor flexibility and low communication capacity.

2) Wireless mode

The wireless mode mainly adopts the wireless network data access service of mobile operators, such as GPRS / CDMA / td-scd, mawcdma / EVDO and updated 4glet network. Advantages of wireless mode: low cost, short construction cycle, strong adaptability, good expansibility, convenient maintenance and easy expansion. However, the mobile data access service of mobile operators has the following disadvantages:

(l) Using the mobile data service of mobile operators requires connecting the electric vehicle charging pile, an internal equipment of the power grid, to the mobile data network of mobile operators, which needs to pay expensive monthly rent and annual fee. With the increase of the number of charging piles, the cost will become larger and larger.

(2) The security of data and the reliability of network are limited by mobile operators, which is not conducive to the safe operation of equipment.

(3) The mobile access bandwidth of mobile operators belongs to shared bandwidth. When a large number of devices are accessed in local areas, the reliability of access and the average bandwidth of each user will deteriorate, which is not conducive to the dense access of charging piles and the transmission of large amounts of data.

2. Charging station (pile) access network scheme

Scheme 1: each charging pile is respectively connected to Ethernet through RJ45 or optical fiber, connected to the charging station management center, and then connected to the Internet management center and database.

Scheme 2: connect the wireless data transmission terminal (charging pile) to Ethernet through RJ45 or optical fiber, connect to the charging station management center, and then connect to the Internet management center and database.

Scheme 3: the charging station is connected to the concentrator through the industrial serial bus (RS-485 / RS-232 / can), and then the concentrator is connected to the Ethernet or mobile data access service through RJ45 or optical fiber to connect the service management platform and database.

Scheme 4: RJ45 connection is made between 3G or 4G industrial wireless router and charging pile. The wireless router can provide richer value-added services, and can establish an efficient and convenient data transmission network for large-scale automobile charging stations. At the same time, the routing function can support portal push, Internet behavior management and flow control functions, and can provide commercial and entertainment program push functions for large-scale charging station operation enterprises, Provide charging car owners with free Wi Fi, Internet surfing and other leisure functions. Through the charging pile intelligent management service platform, users can log in to the web version or use the mobile app client to query the construction distribution, specific location, number of charging piles, free number of charging ports and other charging information of the charging station, and find the nearest charging site for charging.

Scheme 5: Based on the wireless data transmission terminal DTU networking, using 2G / 3G / 4G wireless data transmission technology, based on the server application broadband wired network, provide fixed IP or dynamic IP (domain name binding) and port number, set these server parameters on the wireless transmission terminal DTU, and use it to automatically resolve the domain name address and connect to the charging port of the server

The electric pile management platform can provide a perfect solution for real-time data acquisition, transmission, release, remote management and control, and remote wireless data transmission. The system is mainly composed of AC / DC charging pile, wireless data transmission terminal DTU, various 2G / 3G / 4G wireless networks and communication networks, charging system management platform software, etc.

The wireless data transmission terminal DTU can provide various interfaces such as RS232 / RS485 / RS422 / TTL / terminal to connect with various charging piles with serial port, and has the functions of centralized monitoring, real-time video, video storage, video management, historical track query, audio and video input and output, voice intercom, broadcasting and alarm. If the charging point is an Ethernet interface, you can select wireless router series products with Ethernet interface to connect with it.

The wireless data transmission terminal DTU wirelessly and transparently transmits the data of various charging pile terminals to the charging system management platform on the server side through various wireless networks. The system platform software includes metering and billing system, charging monitoring system, distribution monitoring system, security monitoring system, etc. The management platform of the server can monitor the operation of the charging pile at any time, including the uploading of working parameters of power transmitter, circuit breaker, industrial control host, billing device, touch screen and other equipment, and can also issue various work instructions to the charging pile through the wireless data terminal DTU.

The management platform of the server can monitor the operation status of the charging pile in real time. Once there is a fault alarm, it can be maintained, debugged or upgraded remotely, so as to deal with the problem of abnormal charging pile in time. The management platform of the server can access the third-party app software, and directly provide mobile app for charging users by using GPS equipment and corresponding positioning system software, which can realize the addressing and navigation functions on the map.

3. Requirements for communication network construction of electric vehicle charging pile

As the electric vehicle charging pile on the power distribution side of the power grid, the particularity of its structure determines that the characteristics of the automatic communication system are many and scattered measured points, wide coverage and short communication distance. With the development of cities, network topology requires a flexible and scalable structure. Therefore, the following issues should be considered when selecting the communication mode of electric vehicle charging pile:

(1) Reliability of communication. The communication system shall be subject to harsh environment and strong electromagnetic interference or noise interference for a long time to maintain smooth communication.

(2) Construction costs. On the premise of meeting the reliability, the construction cost and long-term use and maintenance cost shall be comprehensively considered.

(3) Two way communication. It can not only upload the information, but also release the control quantity.

(4) Multi service data transmission rate. With the continuous growth of terminal traffic in the future, the communication from master station to sub station and from sub station to terminal requires higher and higher data transmission rate to realize multi service.

(5) Flexibility and scalability of communication. As the charging pile has the characteristics of many control points, wide range and dispersion, it is required to adopt standard communication protocol. With the development of “allip” network technology and the continuous growth of power operation business, it is necessary to consider IP service bearing, and it is required to be convenient for installation, construction, commissioning, operation and maintenance.