Application of GPRS in the scheduling and Monitoring System of Water Supply Network in the tap water industry
I. project background
The main purpose of the urban water supply network scheduling and monitoring system is to solve the problem that the water supply company collects and monitors the data of the monitoring points in each stage of water supply. The system consists of a monitoring center and various monitoring sites. The data collection terminal (RTU or PLC) of each monitoring point can monitor and collect various data, such as water level, pressure, flow rate, turbidity, residual chlorine, Pump Frequency, etc, it is used for analysis and decision-making by control centers and relevant departments to improve economic efficiency, ensure the quality of water supply, and meet the increasing management needs.
City Water Supply scheduling needs to manage various waterworks, including the control center of the tap water company, the water plant control center, the pipe network pressure station and the pipe network monitoring point. The urban water supply scheduling system generally includes: water Control Center, multiple water plant control centers, multiple Water Plant Monitoring substations, multiple water source well monitoring stations, multiple Pipe Network pressurization stations and multiple pipe network pressure measurement stations.
The city water supply scheduling and monitoring system can monitor and control remote on-site operation equipment to realize data transmission of pipe network pressure, water flow, and automatic control of valve switches, it facilitates timely understanding and control of remote production and operation, reduces the failure rate, shortens the maintenance time, and reduces the number of water stop times. The data collection terminal of each network monitoring point can automatically collect real-time data such as pipeline pressure and water flow. Information is transmitted to the monitoring center of the water company. The monitoring center analyzes the transmitted data, the fault location can be found to solve the problem in the shortest time when a remote node fails.
Currently, the data communication used in the water supply scheduling and monitoring system can be divided into two categories: wired and wireless, among them, wired communication mainly includes the establishment of optical cables, cables or leased telecommunications lines, X.25, DDN, ADSL, etc, wireless communication includes ultra-short frequency communication, spread-spectrum communication, satellite communication, and GSM Short Message/GPRS communication.
In the urban water supply scheduling and monitoring system, some sites are still located in remote locations due to the wide distribution, large quantities, and long distances of various network monitoring sites. Therefore, it is difficult to set up optical cables and high costs, A large number of telephone lines have to be requested for leased lines from the Telecom Department, and the lines at some monitoring sites are difficult to reach. Moreover, when using telephone lines, a long dialing process is required. This process is slow and the operation costs are high, not practical. In short, the monitoring system adopts the wired communication mode, which has a long construction period, is difficult to work, and has high operating costs, which is not convenient for large-scale use. In contrast, the wireless communication mode is very flexible, it has the advantages of low investment, short construction period, simple operation and maintenance, and high cost effectiveness.
In the monitoring system, wireless communication methods mainly include: ultra-short wave (230 MHz) wireless data transmission, spread spectrum, satellite communication, GSM digital cellular communication system, among which satellite communication is expensive due to communication costs, it is only used in some special fields and has not been popularized. Although the spread spectrum communication technology is of high speed, it can only be transmitted within the line of sight, and its applications are also limited. The use of ultra-short frequency data transmission stations as transmission channels has the advantages of flexible networking, easy expansion, convenient maintenance, and low operating costs. However, because the system works at MHz and most data transmission stations adopt common indirect modulation, as a result, the system is vulnerable to external interference, low communication rate, high error rate, low data transmission volume, and low signal coverage.
Ii. Solution Selection
After comparative analysis, we chose China Mobile's GPRS system as the data communication platform of the water supply scheduling and monitoring system. At present, the GSM network has been built by the Telecom Department for many years and covers an ever-expanding range. It has become a mature, stable, and reliable communication network, especially the new GPRS data service launched by China Mobile. The GSM/GPRS system provides wide-area wireless IP connections. The water supply scheduling and monitoring system is built on the GPRS Service Platform of mobile communication companies to realize wireless data transmission of pipe network monitoring points. It has the advantages of making full use of the existing network, shortening the construction cycle, and reducing the construction cost, moreover, the device is easy to install and easy to maintain.
The GPRS wireless monitoring system has the following features:
1. good real-time response and processing capabilities. Compared with short message service, due to the real-time online feature of GPRS, the system has no latency, and the system can collect and process various data from multiple monitoring sites in real time at the same time, it can meet the requirements of the system for real-time data collection and transmission.
2. Remote Instrument and Equipment Control: the two-way communication between the monitoring center and remote equipment can be achieved by using the GPRS two-way transmission system;
3. Low construction cost: the existing GSM network can be fully utilized, and devices can be connected immediately after installation. However, when using ultra-short wave communication, the on-site environment should be fully taken into account, and ancillary equipment such as antenna iron frames should also be provided.
4. simple installation and debugging, and short construction period: using the existing mature GSM network, the system does not need to be debugged when it is put into operation, and the installation is simple. The installation and debugging work is heavy when ultra-short wave communication is used. It is necessary to perform on-site signal testing, erection of antenna iron frame, and commissioning of antenna direction angle.
5. wide coverage. The construction of a water supply scheduling monitoring system requires a wide range of data communication coverage, unlimited resizing, and unlimited access locations, which can meet the access needs of mountainous areas, towns and cross-regional areas.
Due to the large number of pipe network monitoring sites, some pipe network monitoring sites are located in remote areas and their geographical locations are scattered. Ultra-short wave communication is adopted, with a coverage of more than 30 kilometers. However, GPRS can be used to achieve monitoring in theory within the coverage of wireless GSM/GPRS networks.
6. High data transmission rate. In theory, the GPRS network transmission rate can reach 171.2 kbit/s, and the actual data transmission rate is around 40 kbps. At present, the average transmission rate of ultra-short wave data transmission stations is 2.4 kbit/s or lower.
7. The system's transmission capacity is large. The monitoring center must be connected to each network monitoring site in real time. Due to the large number of pipe network monitoring sites, the system requirements can meet the needs of sudden data transmission, and GPRS technology can meet the needs of sudden data transmission.
8. Low communication costs. Because GPRS uses the monthly billing method, the operation and maintenance costs are low, and the monthly communication fee will be within dozens of RMB.
Iii. solution introduction
Because GPRS communication is an IP address-based Data grouping communication network, the host of the monitoring center is configured with a fixed IP address, and the GPRS module of each end station communicates with the host.
(1) system composition
1. Pipe Network Monitoring site:
Pipe Network Monitoring site: each monitoring site collects pressure, traffic, and other data through the data collection module. It is connected to the GPRS transparent data transmission terminal through the RS232 (RS485) interface and has no standard communication interface, we can also use the gprs rtu with the functions of collecting analog quantities and switch quantities. The embedded processor is embedded in the GPRS transparent data transmission terminal to process the data, encapsulate the protocol, and send it to the GSM network.
2. Monitoring Center:
The server requests to configure a fixed IP address and uses the leased line provided by the mobile communication company to connect to the GPRS network. Because the leased line can provide high bandwidth, when the number of monitoring sites in the pipe network increases, the center does not need to be resized to meet the requirements.
The monitoring center server receives the connection request from the GPRS network terminal for authentication first. After the authentication is passed, the server receives and processes the incoming data.
3. GPRS/GSM mobile data transmission network:
The data collected by the on-site monitoring site is decoded by the GSM network air interface function module and converted to the public network data transmission format. The data is transmitted through China Mobile's GPRS wireless data network, the IP address is finally sent to the monitoring center.
(2) system solution
Each monitoring site uses a GPRS transparent data transmission terminal to connect to the monitoring center through a mobile GPRS network.
Each data collection point uses a unified STK card of the mobile communication company. At the same time, the monitoring center registers each point and stores relevant information for identification and maintenance. Each information collection point runs the monitoring system software, and supports 24 hours of real-time online, information collection point 24 hours to transfer the collected information data.
All information collection points authorized by the tap water company can use this system:
1. The Pipe Network Monitoring site must use a uniform STK card. You can only use this card for data communication with the monitoring center.
2. User Registration: It complies with the regulations of the tap water company.
(3) Product Features
The system uses a GPRS wireless transparent data transmission terminal. The product is based on China Mobile's GPRS network and features high performance, high reliability and strong anti-interference ability. It provides standard RS232 (RS485) data interfaces can be directly connected to computers, RTU, PLC, GPS receivers, digital cameras, and various instruments and instruments with standard communication interfaces, we can also use the gprs rtu with the functions of collecting analog quantities and switch quantities. The transmission rate reaches 171 kbps. It has the functions of remote diagnosis, testing and supervision, and can meet the data collection and control needs between scheduling or control centers in various industries and numerous remote devices.
Using GPRS to build a water supply scheduling and monitoring system, there are currently two charging methods: monthly subscription and data traffic. The traffic is calculated at 0.03 RMB/kilobytes, while the monthly subscription system at 20 RMB/month provides 1024 Kbyte traffic, it can meet the actual data volume of the current monitoring system and is estimated that the cost will gradually decrease in the future. Users enjoy low communication costs. In addition, because the access equipment can be moved, the equipment can be migrated and used when the pipe network monitoring site is relocated, which can protect users' original investment and is suitable for the characteristics of water supply scheduling and monitoring, it can meet the needs of water supply monitoring.
Our company has installed more than one hundred flow meters on the internet, effectively reducing the production/sales ratio. Recently, it began to implement real-time monitoring for large users to install traffic meters, effectively preventing users from stealing water. If you are interested, contact us.
Yixing water group and Information Technology Co., Ltd. Contact person: Chen Mr 13961501079