With the development of society and economy, the impact of water on people’s lives and production has been increasingly strengthened. The demands for the quality and safety of water supply have been continuously improved, and people have also paid more attention to reducing the energy consumption of water supply systems. For this reason, an important and effective The measure is to strengthen the monitoring of the working conditions of the water supply system, and in particular, to strengthen the automatic monitoring and control of various processes in the water treatment plant.
In the urban water supply dispatch monitoring system, because of the characteristics of wide distribution, large number, long distance, isolated locations, and bad environment of each pipe network monitoring point, it is obviously unrealistic to select wired communications. In contrast, the use of wireless data radio station is very flexible. It has the characteristics of low investment, short construction period, high real-time reliability, simple operation and maintenance, and has a very high cost performance compared with other transmission equipment.
System solution composition This system adopts two levels of control: one is the water company monitoring center; the second is each monitoring point. The block diagram is as follows:
The configuration example system consists of a master station (Water Monitoring Center) and N substations (monitoring points). Each monitoring point uses RTU (PLC) to collect the pressure, flow, and liquid level of the water supply pipe network, and to control the start, reset, and stop of the pumping pump of the pump house. The collected data is uploaded to the monitoring center in real time through a digital radio station. The computer of the monitoring center further processes and analyzes the collected data to monitor the operation of the entire water supply pipe network. If there is an abnormality in the parameters of a measurement site, various control commands are sent through the digital radio station to control the outside. Station RTU (PLC) and lift pump operation to avoid possible problems such as air pumping, excessive pipe pressure, etc.
The overall block diagram of the system is as follows:
System program analysis:
The system uses one-to-many networking; the half-duplex protocol is transparently transmitted. The central dispatch office is located on the top floor of the office building of the Water Company. The central dispatch office and each monitoring site use digital radio point-to-multipoint communication. Wireless communication adopts the master-slave communication protocol with SCADA function, and RTU (PLC) connects with the digital radio through its standard RS232 interface or 485 interface to realize wireless communication. The communication speed can be selected up to 9600 bps or 19200 bps. The central dispatch office can implement real-time monitoring of the water plant automation system and can also control it.
Center control room function: In the control room computer, software is used to read water plant parameters (factory water pressure, flow rate, pH, residual chlorine, a small number of parameters such as pump start, stop, and fault status) and pipe network pressure data; PC monitoring software It is used to monitor the water plant production process and pipe network pressure to achieve a reasonable water supply dispatch. The monitoring computer in the dispatch room can monitor the site through screens and curves. The water supply dispatcher can perform production scheduling and command of the water plant based on the collected data, and can also print various reports.
RTU (PLC) is placed in monitoring points such as pressure, flow, and liquid level that need to be monitored according to their different uses. Responsible for the collection of various data such as pressure, flow, and liquid level, and implement various control functions of the pipe network according to the instructions of the central dispatch office. The RTU (PLC) receives various commands from the central dispatch office through the digital radio station, and transmits real-time data or performs various control functions to the central dispatch office according to the instructions.
The hierarchical management structure is as follows:
Note: In the larger urban water supply system, there may be multiple water plants under the water supply company. The larger water plant has multiple process processes and is also responsible for multiple pipe network pressure measurement stations and pipe network pressurization stations. Water source monitoring station management. If all the system information is transmitted directly to the water control center, it is unreasonable for the Water Division to control the entire system. Therefore, it is necessary to establish multiple water plant sub-control centers to establish multiple sub-stations for monitoring and tap water intake and water supply monitoring sites in the water plant so as to realize the progressive transmission of information and the hierarchical control of the system.
Water plants can choose different ways to establish automatic control systems according to their own different situations (refer to the GD series of water plant automation programs). In order to facilitate unified management, the central dispatch office and the waterworks automation center use digital radio point-to-point communication. The real-time data transmitted by the water control center through the central dispatch office can also monitor the operation status of each monitoring point of the pipeline network and each small water plant. The water plant automation center monitors the production of the water plant and each site in real time. It is the system's information collection and control center. The water plant automation center collects data information of each site, and stores, analyzes, summarizes, or prints such information. Through data analysis, timely giving alarm information or issuing control commands to the site to control the operation of the site equipment. Water plant automation center also needs to transmit the summary data to the Water Division monitoring center in real time, and the Water Division Monitoring Center does further processing and analysis of the data to reasonably implement the scheduling and management of the entire system.
System Advantages • Replaced fiber optics and dedicated lines, reduced network construction costs, and saved users a lot of money;
· Short construction period;
·Flexible and easy installation;
Strong expansion;
Provide high reliability
Provide remote real-time monitoring;
High transmission rate, up to 19.2kbps;
Low equipment cost and high cost performance.
The city water supply dispatch monitoring SCADA system can monitor and control the remote on-site operating equipment to realize the data transmission of the pipeline pressure and water flow and the automatic control of the valve switch, which reduces the failure rate and improves the reaction time to the system. It is convenient for promptly understanding and controlling the remote pipes and valves, reducing the failure rate and maintenance time, and reducing the number of water stops. The data collection terminal of each water source monitoring point can automatically collect data such as pipeline pressure, water flow real-time data and switch status, and the information is transmitted to the water company's monitoring center. The monitoring center can analyze the data transmitted back to find the fault. Location, so that when a remote end fails, it can solve the problem in the shortest time, restore water supply, improve the overall level of service, thus achieving the city's water supply information and modernization.