I. Introduction
SCADA (Supervisory Control And Data Acquisition) system SCADA system is a computer-based production process control and scheduling automation system. It can monitor and control on-site operating equipment to achieve various functions such as data acquisition, equipment control, measurement, parameter adjustment, and various signal alarms.
As an important public infrastructure of a city, city gas is one of the important symbols of a modern civilized city, and at the same time, it is an important part of the country's energy construction. Its application fields are extremely wide, such as chemical industry raw materials, industrial fuels, commercial and civil fuels, automobile fuels, central heating and power generation, etc., which is one of the main one-time energy consumption.
The characteristics of urban gas companies are: distributed, distributed, networked, and fully open. In order to realize the safe and efficient dispatch and command of the city gas production process, a reliable control system is urgently needed.
Although Daqing is the largest oil city in my country, the development and application of city gas is just in its infancy. The starting point directly affects the level of Daqing's application of urban gas, and also directly affects its future development. Therefore, it is necessary to adopt an advanced centralized data model platform to manage the entire production operation, and adopt common standards to make the system have enterprise interconnectivity, and provide a two-way information high-speed channel with related systems, so that managers and users can accurately and in real time. Make business decisions. Through research at home and abroad, our company decided to develop a world-class advanced level of urban gas production dispatch command system. SCADA (Supervisory Control And Data AcquisiTIon) system, that is, data acquisition and monitoring control system, is an automation system that combines computer-based production process control and remote dispatching. It has been widely used in power systems, natural gas gathering and transportation, petrochemicals, etc. Many areas. The SCADA system can collect field data in real time, perform local or remote automatic control of industrial sites, conduct comprehensive and real-time monitoring of technological processes, and provide various functions such as necessary data for production, scheduling and management.
Two SCADA system flow design
The data collection of the Daqing Natural Gas SCADA system includes 5 CNG sub-stations and a pressure regulating station.
The on-site data acquisition and monitoring system composed of RTU at the pressure regulating station is uploaded to the production dispatching command center through GPRS. The CNG sub-station is connected to the monitoring center through ADSL. The dispatch center completes the data communication and all production data monitoring and collection of CNG filling stations and surge tanks distributed throughout the city through the man-machine interface system. The monitoring parameters of each monitoring station are displayed 24 hours a day uninterruptedly, and management functions such as alarm recording, event recording, and main production data storage and archiving, report output and other management functions are realized.
Three data collection of CNG sub-station and communication of monitoring center
Each CNG sub-station includes a data acquisition machine, which uses opto to collect meter data. The required data items can be collected through the OPC SERVER provided by the software. The specific method is as follows:
First enter the configuration of the Zijinqiao configuration software, create a new OPC device and select the "opto" OPC Server in the "OPC Server" in the "Define OPC Device" dialog box.
Select "Confirm", and an OPC device is created.
Then, set up the connection point with the device in the "Point Configuration" window. Double-click the blank item in the table, and the "New Database Point Dialog Box" will pop up. Select the previously established OPC device in the drop-down box of the data connection item in the dialog box.
Finally, the data communication between CNG station and monitoring center is realized through remote data source. Double-click the "Data Source" item in the "Public" navigation page of the Zijin Bridge configuration software on the server side, and fill in the remote data source name in the pop-up dialog box; fill in the IP address of the remote data source in the subsequent dialog box . Select the remote device when defining the point in the "Point Configuration", and select the defined data source in the drop-down box.
Communication between data collection and monitoring center of four pressure regulating stations
The data acquisition equipment of the pressure regulating station includes a flow meter, a pressure transmitter and an analog input module; the pressure, flow, and temperature of natural gas can be collected through the flow meter; the pressure before and after pressure adjustment can be collected through the pressure gauge; through simulation The input module can convert the current value into a digital signal.
The data collection of the flowmeter can realize the data transmission between the device and the computer by defining the corresponding device under the "device driver".
The data acquisition of voltage change can be achieved by outputting the output current value to the analog input module, and then transmitting the output digital signal to the computer, and converting the signal into a digital value through the device driver of the Zijinqiao software.
Due to the remote location of the voltage regulating station and the high cost of setting up a dedicated line, wireless communication can be used here to transmit the digital signal to a remote computer through the GPRS network through the wireless module. It should be noted that the baud rate of the flow meter and the analog input module should be set the same. The figure below is a simple wiring diagram.
Five configuration screen drawing
After all the data is uploaded, the configuration screen can be drawn, and the data display and report function application can be realized on the premise of practicality and beauty.
1 Login interface
The interface provides login, password and maintenance functions, and can display the user's login status.
2 Geographical navigation
Select the corresponding site by selecting the button in the upper left corner. You can also select the yellow area on the map to enter each station.
3 Data display
The status of remote data is displayed through the data display of each graph and the color of the valve. And can check the trend over a period of time.
4 Report
The Zijinqiao configuration software provides powerful report functions, which can be used to display, summarize, print and store the received data.
You can generate daily reports, upload data, modify users and print functions through the report.
Six network release
The completed projects can be published through the WEB, and the pictures made can be published on the Internet. The specific method is as follows:
In "Public"-"Local Configuration", select "WEB Server"; fill in the IP address of the WEB server in "WEB Configuration"; select "File"-"Publish all to WEB" to complete publishing. At this point, the network segment to which the WEB publication belongs can be accessed by entering the IP address in the IE browser.
Seven Conclusion
The above text is the preparation process of natural gas SCADA system. In actual application, it will encounter many aspects such as network, GPRS signal, computer virus and so on.
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