EGAT-SCADA Communication Network Structure: A Comparison between Direct Scan and Hierarchy Scan to RTU

The Electricity Generating Authority of Thailand (EGAT) has developed an in-house supervisory control and data acquisition (SCADA) system for a decade. This paper describes the details together with advantages and disadvantages of two EGAT-SCADA communication systems. The first configuration called hierarchy scan (HS) (Zhaoxia Xie, et al., 2002) is originally designed to reduce the number of dedicated communication lines. With this configuration, the EGAT-SCADA at a control center retrieves data from a remote terminal unit (RTU) by communicating through computerized control systems at a group control center and substation, respectively. The other configuration called direct scan (DS) (S. Gulle, et al., 2004) has been selected as a preferred configuration. Utilizing the existing communication links from the obsolete SCADA systems, the control center is able to retrieve the data directly from the RTUs. In this paper, the comparison between the two configurations is described. We also propose the future configuration of the EGAT-SCADA as the optimum choice