Traian Turc SCADA application based on real-time database
SCADA APPLICATION BASED ON REAL-TIME DATABASE
TRAIAN TURC
University: “Petru Maior “ of Targu Mures
Address: N.Iorga nr 1 Targu Mures
email:
ABSTRACT:
The full paper describes a SCADA software application based on real-time database, implemented on gas plant.
SCADA software application is based upon a real-time database (RTDB) located in server. Servers are responsible for data acquisition and handling.
The main purpose of SCADA system is remote monitoring and controlling of gas plant.
Data gather from gas plant is centralized and displayed at the station office headquarter and, using dynamics WEB pages, also sent to a large number of users.
The main benefit of using SCADA is real time displaying of gas plant state.
The main contribution of the author consists of the SCADA software application, database architecture , and the monitoring system using dynamic WEB pages.
- Introduction
In gas plant, safety is one of the most important issue. In order to increase safety level and get more reliability and robustness a SCADA system is implemented.
SCADA systems are used to monitor and control gas plant. SCADA system is used also for gathering and analyzing real time data.
A huge amount of data gathered by the SCADA system is managed using a real-time database. Data base is the main part of SCADA system. In order to share date with a large number of SCADA Clients a Internet Based Data Base is used.
Using dynamic web pages SCADA clients cud display gas plant state using any computer connected to the Internet, no matter what browser it is used.
- Hardware Architecture
Figure 1 SCADA Hardware Architecture
The SCADA servers communicate with devices in the field through serial line RS 232 . RTU (Remote Terminal Unit) and Base Radio are connected on RS485 in multi drop system.
RTU is a installed at a remote location and collects data from actuators, codes the data into a format that is transmittable and transmits the data back to SCADA Server. RTU also collects information from SCADA Server and implements processes that are directed by the SCADA Server. RTU is equipped with input channels for sensing or metering, output channels for control, indication or alarms and a communications port.
The main purposes of RTU is to interconnect field devices (actuators) with the SCADA Server through a MODBUS RTU interface card.
The TRU transfers all the information from the field to the higher lever of the control system (SCADA Server).This function gives total control of the plant. Data are transmitted, by MODBUS RTU communication protocol, through serial line RS485.
Data transferred are relevant to the variables transmitted with each actuator and to the actuator physical sequence on MODBUS map.
RTU is also capable of executing simple programs autonomously without involving the SCADA Server to simplify deployment, and to provide redundancy for safety reasons.
Base Radio collects data from wire less pressure sensors and transmits the data to SCADA Server.
A converter RS232-RS485 is used to connect SCADA server to serial line RS485.
SCADA Servers are connected to SCADA Clients and WEB Server stations via an Ethernet LAN. Fig.1.shows typical hardware architecture.
- SCADA Software Architecture
The SCADA server application is multi-tasking and are based upon a real-time database (RTDB) located in SCADA Server
SCADA Servers is responsible for data acquisition and data storing in RTDBE.
Figure 2 SCADA Software Architecture
Data transferred from RTU are stored in Internet based real-time database,
called “cons_el”.Data are stored using several tables. For instance data from actuators are stored in table called “actuators”. Structure of “actuators” table is shown in figure 3.
Figure 3 Actuators table
Similarly, data transferred from Base Radio are stored by same Internet based real-time database, in table called “pressure”. Structure of “pressure” table is shown in figure 4.
Figure 4 “Pressure” table
- HMI
HMI (Human Machine Interface) presents process data to a human operator, and through this, the human operator, monitors and controls the process.
By providing information, alerts, commands and other tools, an HMI connects the user with the process being controlled.
HMI is a graphical user interface that includes controls where the operators can interface with the SCADA system.
SCADA client application offer an intuitive and user-friendly HMI. As is shown in figure 5 HMI mimics gas plant and operators cud see an electronic “mirror” of gas plant.
SCADA client application offer also support multiple screens, which can
contain combinations of synoptic diagrams and text, in order to display event lists,
alarm lists, trends.
Figure 5 Human Machine Interface
- Trending
SCADA client application provide trending facilities (see figure 7) having a lot of capabilities as follows:
selecting the parameters to be trended in a specific chart
a chart may contain more than up to 8 trended parameters
historical trending is possible for any archived parameter
zooming and scrolling functions are provided
parameter values at the cursor position can be displayed
1
Figure 8 Trending
- Conclusion and Future Work
The full paper significantly contributes to computer assisted controlling and monitoring of the gas industry processes, especially when it comes to aggregates for natural gas compression.
As a result of the process of functioning parameters monitoring, a notification system has been realized. Operators are informed on the situations when the aggregate deviates from the normal functioning parameters. The notification involves both the local console and the dispatcher, where the state of every aggregate is displayed on the monitor of the central computer.
A discrete algorithm for the regulator has been determined and the revolution speed of the aggregates in the compression station is automatically controlled.
As a result of the acquisition and processing of the data provided by the automation and monitoring systems, optimal functioning conditions of the aggregates could be determined and maintained. Another achievement was the increase in the quantity of compressed gases.
Due to the permanent monitoring of the numerous functioning parameters of the aggregates, protection measures could be taken in case of unexpected errors and damages of the subsystems were avoided. As a consequence, maintenance costs decreased. The error auto-detection facilities included in the automation and monitoring system lead to an easier maintenance.
On the basis of the data analysis, the optimum functioning parameters have been detected and maintained at this rate. The results that were obtained can be considered to be useful solutions for automating and monitoring other types of compressors or aggregates belonging to gas industry and even other industrial fields. The solution that was proposed in this paper were implemented in four compression stations on more than 45 compression aggregates.
The embedded system DASYS used for automation and monitoring of several types of compression aggregates represents the patent for which the author obtained the patent no. 118683 B1/2004 entitled: “Industrial Processes Automation and Monitoring System”
The next research includes the using of intelligent sensors and intelligent maintenance system based on a neural networks.
- References
[1] Gavril Toderean, Microprocesoare Univ. Tehnica Cluj, 1994
[2] Mircea Dulau, Automatizarea proceselor termice si chimice- Universitatea „Petru MaiorTargu Mures, 2002
[3] Traian Tur,Brevet de inventie nr:11863 “Sistem pentru automatizarea si monitorizarea proceselor industriale”, OSIM, 2003
[4] Munteanu,R., Tarnovan,I.G., Dragomir,N.D., Popovici,O. – Electrotehnică şi convertoare energetice. Editura MEDIAMIRA, Cluj-Napoca, România, 1997.
[5] R. Hyde, “AoA - The Art of Assembly language”, webster.cs.ucr.edu/AoA/DOS/pdf/
[6] S. Nedevschi, “Microprocesoare”, Editura UTCN, 1994
[7] T. Leţia, A. Aştilean, „Sisteme cu evenimente discrete”, Editura albastră, 1998
[8] T. Leţia. Programarea avansată în Java. Editura Albastră (Microinformatica), 2002
[9] M. Damian, I. Revnic, M. Balan, L. Miclea, H. Vălean, Realizarea siturilor şi aplicaţiilor pentru web, Ed. U.T.Pres, 2005
[10] Texas Instruments-Precision Data Acquisition Applications Seminar-2004
sef lucr.dr.ing. Turc Traian
Department: Engineering Faculty
University: “Petru Maior “ of Targu Mures
Address: N.Iorga nr 1 Targu Mures
email: