Design, Simulation, and Analysis of Substation Automation Networks
Kembanur Natarajan, Elangovan
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Society depends on computer networks for communication. The networks were built to support and facilitate several important applications such as email, web browsing and instant messaging. Recently, there is a significant interest in leveraging modern local and wide area communication networks for improving reliability and performance in critical infrastructures. Emerging critical infrastructure applications, such as smart grid, require a certain degree of reliability and Quality of Service (QoS). Supporting these applications requires network protocols that enable delay sensitive packet delivery and packet prioritization. However, most of the traditional networks are designed to provide best effort service without any support for QoS. The protocols used in these networks do not support packet prioritization, delay requirements and reliability. In this thesis, we focus on the design and analysis of communication protocols for supporting smart grid applications. In particular, we focus on the Substation Automation Systems (SAS). Substations are nodes in the smart grid infrastructure that help the in transportation of power by connecting the transmission and distribution lines. The SAS applications are con figured to operate with minimal human intervention. The SAS monitors the line loads continuously. If the load values are too high and can lead to damage, the SAS declares those conditions as faults. On fault detection, the SAS must take care of the communication with the relay to open the circuit to prevent any damage. These messages are of high priority and require reliable, delay sensitive delivery. There is a threshold for the delay of these messages, and a slight increase in the delay above the threshold might cause severe damages. Along with such high priority messages, the SAS has a lot of background traffic as well. In spite of the background traffic, the substation network must take care of delivering the priority messages on time. Hence, the network plays a vital role in the operation of the substation. Networks designed for such applications should be analyzed carefully to make sure that the requirements are met properly. We analyzed and compared the performance of the SAS under di erent network topologies. By observing the characteristics of the existing architectures, we came up with new architectures that perform better. We have suggested several modi cations to existing solutions that allow significant improvement in the performance of the existing solutions.