GPRS wireless power remote meter reading system

　　The way of knocking door to door to check the electricity meter is a troublesome thing for both the knocker and the knocked. At present, many residential users have used prepaid electric cards to save the trouble of looking up tables, but for the power department, data statistics and real-time monitoring are still a problem to be solved.

　　1、 Scheme introduction

　　Through the GPRS network system of China Mobile, the power department can transmit the power system data collected by industrial and civil electricity meters to the centralized monitoring centers at the local, municipal and provincial levels in real time, so as to realize the unified monitoring and distributed management of power monitoring equipment. GPRS network can provide a simple and efficient means of communication transmission for power system.

　　China mobile GPRS system can provide wide area wireless IP connection. Building a power remote meter reading system on the GPRS service platform of mobile communication company to realize the wireless data transmission of meter data has the advantages of making full use of the existing network, shortening the construction cycle and reducing the construction cost, and the equipment installation is convenient and the maintenance is simple.

　　GPRS power remote meter reading system consists of the distribution center located in the power bureau and the meter data acquisition point located in the residential area. Using the existing GPRS / GSM network of China Mobile, the meter data is transmitted through the GPRS / GSM network of China Mobile. All electricity meters in the residential area are first connected to the meter concentrator. The electricity consumption data of residential users is transmitted from the multi rate meter to the meter concentrator through RS485 bus. The meter concentrator is connected with the GPRS DTU transparent data transmission terminal through RS232 interface. The meter data is encapsulated by the protocol and sent to the GPRS data network of China Mobile, The data is transmitted to the distribution data center through GPRS data network to realize the real-time online connection between the meter data and the data center system.

　　2、 Scheme advantages

　　GPRS wireless power remote meter reading system has the following characteristics:

　　1. High reliability:

　　Compared with SMS short message mode, GPRS DTU adopts connection oriented TCP protocol communication, which avoids the phenomenon of data packet loss and ensures reliable data transmission. The center can transmit data with multiple acquisition points at the same time without mutual interference. GPRS network itself has perfect frequency division multiplexing mechanism and strong anti-interference performance, which completely avoids the phenomenon of multi machine frequency band "collision" of traditional data transmission radio stations.

　　2. Strong real-time performance:

　　GPRS has the characteristics of real-time online, small data transmission delay and supports multi-point simultaneous transmission. Therefore, GPRS monitoring data center can carry out two-way communication between multiple monitoring points quickly and in real time, which can well meet the requirements of the system for real-time data acquisition and transmission. At present, the actual data transmission rate of GPRS is about 30kbps, which can fully meet the demand of system data transmission rate.

　　3. Wide range of centralized reading:

　　GPRS network has achieved nationwide coverage, unlimited capacity expansion and unlimited access locations, which can meet the access needs of mountainous areas, towns and cross regions. Due to the large number of environmental protection information collection points, which are distributed throughout the province and within the coverage of wireless GSM / GPRS network, the centralized reading control and management can be completed.

　　4. Low system construction cost:

　　Due to the use of GPRS public network platform, there is no need to build a network, just install equipment, and the construction cost is low; It also eliminates the cost of network maintenance.

　　5. Low system operation cost:

　　GPRS public network communication is adopted, which is charged according to the unified rate throughout the country, eliminating the expensive roaming cost. GPRS network can be charged according to the actual data communication flow (1-3 points / 1K bytes), or it can be charged according to the monthly unlimited flow, so as to realize the low-cost communication of the system.

　　6. The meter equipment can be remotely controlled:

　　The GPRS bidirectional system can also realize the remote control of electricity meter equipment, such as remote parameter adjustment, remote status query, remote switch control and so on.

　　7. The system has large transmission capacity and good capacity expansion performance:

　　The distribution data center shall maintain real-time connection with each meter data acquisition point. Due to the large number of data acquisition points of electric meter, the system is required to meet the needs of sudden data transmission, and GPRS technology can well meet the needs of sudden data transmission; As the system adopts mature TCP / IP communication architecture and has good expansion performance, a monitoring center can easily support the communication access of thousands of meter data collectors.

　　3、 System construction

　　Since GPRS communication is a data packet communication network based on IP address, the monitoring center computer needs a fixed IP address or fixed domain name. Each meter data acquisition point uses GPRS module to access the host through IP address or domain name for data communication.

　　(1) System composition

　　1. Meter data acquisition point:

　　The electricity meter data acquisition point is located in the information center of the residential area. The electricity consumption data of the residential user is first connected to the electricity meter concentrator located in the information center of the residential area through RS485 interface and twisted pair, and then connected to the GPRS transparent data transmission terminal through RS232 interface. The embedded processor is built in the GPRS transparent data transmission terminal to process the data, encapsulate the protocol and send it to the GSM network. It is transmitted to the power remote meter reading system in the data center of the power company through the GPRS network to realize the real-time online connection between the meter data and the data center system.

　　The meter concentrator is directly connected to the meter through RS485 interface, which can support either a single meter or multiple meters at the same time, realize the acquisition, storage, preprocessing or of meter parameters, and transmit the collected meter data to the distribution center in real time; At the same time, the meter concentrator can also transmit the remote control command sent by the distribution center to the meter control module to control the meter.

　　2. Distribution center.

　　a) Public network access scheme

　　The server uses public network to access the Internet, such as ADSL dial-up / Telecom special line broadband Internet access, and applies for public network fixed IP address; It can realize the application of small and medium capacity meter data acquisition.

　　b) Private network access scheme

　　The server adopts the DDN special line provided by the provincial mobile communication company to apply for the configuration of fixed IP address and connect with GPRS network. As the DDN dedicated line can provide high bandwidth, when the number of meter data acquisition points increases, the center can meet the demand without capacity expansion, and can realize high-capacity data acquisition applications.

　　After receiving the data from GPRS network, the radius server of the monitoring center first performs AAA Authentication and then transmits it to the computer host of the monitoring center. The data is restored and displayed through the system software and processed, which further enhances the security performance of the system data communication.

　　The computer host of the distribution center can carry out business management and billing management, verify, calculate, store, analyze and manage the power data, alarm the abnormal conditions, and monitor the user's use in real time to ensure the legitimate income of the power bureau.

　　3. GPRS / GSM mobile data transmission network:

　　The data collected by the meter concentrator is decoded and processed by the GPRS / GSM network air interface function module at the same time, converted into the format of data transmission in the public network, transmitted through the GPRS wireless data network of China Mobile, and finally transmitted to the IP address of the monitoring center.

　　(2) System scheme

　　Each electricity meter uses GPRS transparent data transmission terminal and is connected to the distribution center through mobile GPRS network.

　　The electricity meter uses GPRS ordinary data card or APN special data card. At the same time, the monitoring center registers the GPRS terminal number of each point and associates it with the information of the acquisition point for identification, maintenance and processing. The data acquisition center runs the system software of the data acquisition center to collect electricity meter data in real time.

　　All information collection points authorized by the power bureau can use the system:

　　1. The electric meter data acquisition point must use the mobile unified APN card, and the user can only use this card to communicate with the data center of the power supply bureau.

　　2. The terminal equipment uses the GPRS mobile data communication terminal provided by mengwang technology company.

　　3. User registration: in accordance with the provisions of the power supply bureau.

　　It is recommended that provincial distribution centers use APN to access mobile GPRS network through public network, which has low cost, high security, and guaranteed speed and network service quality; It can also be connected to the mobile GPRS network through GPRS special line, which has the advantages of high cost, high security, stability and reliability.

　　Since GPRS communication is a data packet communication network based on IP address, the computer host in the distribution center is configured with a fixed IP address, and each meter data acquisition point adopts GPRS module to communicate with the host.

　　(3) Product characteristics

　　The system adopts mrm6155 DTU wireless transparent data transmission terminal. Based on the GPRS network of China Mobile, the product has the characteristics of high performance, high reliability and strong anti-interference ability. It provides standard RS232 / RS485 interface, which can be directly connected with PC, single chip microcomputer system, RTU measurement and control terminal, PLC, GPS receiver and data concentrator. It has the functions of remote diagnosis, testing and supervision, Meet the data acquisition and control between the dispatching or control center of various industries and many remote stations.

　　Highly integrated GPRS and TCP / IP technology can realize flexible wireless networking modes such as point-to-point and point to multipoint

　　Built in embedded CPU completes complex network protocols, supports PPP, ICMP, TCP, UDP, DNS and other protocols, and provides transparent transmission channels for user data

　　Stable performance, ensuring long-term reliable operation in harsh environment, with built-in watchdog circuit

　　Always online mode is supported. Users can set heartbeat interval and heartbeat packet to keep the device online for a long time

　　In case of network failure or center shutdown, DTU has the function of automatic reconnection after conditional recovery

　　DTU can work in fully transparent transmission mode to ensure 100% no loss unless network failure

　　DTU can work in fully transparent transmission mode and user instruction mode to give DTU the dual role of fool and flexibility

　　The support center is fixed IP or dynamic IP + dynamic domain name resolution

　　RS232 / RS485 / RS422 communication interface is provided. Baud rate can be selected from 300BPS to 115200bps. Start bit / stop bit / parity can be selected, and RTS / CTS flow control can be selected

　　Support near end and remote parameter configuration and access

　　Support remote wake-up

　　Built in flash memory can save user configured parameters for a long time

　　Support serial port firmware upgrade program

　　Support APN data private network service

　　Anti interference design, suitable for applications with harsh electromagnetic environment

　　(4) Safety measures

　　Due to the particularity of power remote meter reading system, this system needs very high system security and stability. Security is mainly to prevent intentional and unintentional damage from inside and outside the system. Stability means that the system can 7 × 24-hour uninterrupted operation. Even if there is hardware and software failure, the system cannot be interrupted.

　　1. APN data private network mode: APN server is configured in the internal network of the enterprise, and the mobile terminal uses APN data private network. Due to the use of data private network, the server is isolated from the public Internet, which can effectively avoid illegal intrusion.

　　2. Use the uniqueness of the SIM card to authenticate and authorize the user's SIM card mobile phone number, bind the SIM card number and APN on the network side, and delimit the scope that the user can access a system. Only the SIM card mobile phone number belonging to the specified industry can access the special APN, and the mobile terminal and data center use the special APN allocated by China Mobile for wireless network access, The SIM card number of an ordinary mobile phone cannot call a special APN.

　　3. The DTU ID number and password can be configured separately for each GPRS data transmission device, and the application layer authentication can be carried out when logging in through the data center. Other GPRS devices without DTU ID number and password assigned by the data center will not be able to log in and enter the system, and the security of the system will be further enhanced.

　　4. Data encryption: it can encrypt and protect the whole data transmission process.

　　5. Network access security authentication mechanism: adopt firewall software and set network authentication and security protection functions to ensure system security.

　　4、 Conclusion

　　For the power sector, remote substation meter reading has always been a headache, which requires a lot of human, material and financial resources. Because of the large number of substations and scattered geographical location, it brings great inconvenience to the staff. Power companies can also use GPRS mobile data network to monitor all important power nodes, automatically read and analyze relevant data, and further carry out remote control or equipment maintenance, which can reduce human resources, shorten repair time and save special line construction cost.