COMMITTEE CHAIR: Dr. Annamalai Annamalai

TITLE: STRENGTHENING SMART GRID CYBER-PHYSICAL RESILIENCE THROUGH COMMUNICATION-PROTOCOL BASED DOS DETECTION AND PREDICTIVE MITIGATION

ABSTRACT: This dissertation investigates the impact of communication-protocol-based Denial-of-Service (DoS) attacks on smart-grid cyber–physical stability through a comparative evaluation of Secure Shell (SSH) and Telnet protocols. A hardware-in-the-loop (HIL) experimental platform was developed, featuring a multi-bus smart-grid system integrated with SCADA control, real-time network monitoring, and synchronized cyber–physical data acquisition. Controlled attack scenarios—specifically brute-force authentication and SYN flood resource exhaustion—were executed under identical conditions. Experimental results demonstrate that communication-layer disruptions propagate directly into the physical grid, producing measurable instability. Frequency emerged as the dominant indicator of this instability, with deviations reaching up to 39 Hz, while voltage remained within bounded variations of ±1–5 V. Telnet-based attacks resulted in a mean frequency degradation of 24.96 Hz, compared to 16.28 Hz under SSH—representing approximately 53% greater instability in the Telnet environment. Protocol performance analysis indicates that SSH maintains higher resilience despite increased computational load (CPU utilization up to 71%), whereas Telnet exhibits faster failure due to a lack of encryption and authentication controls. Network-level observations revealed increased latency, packet loss, and authentication failures, with a corresponding degradation in SCADA communication and control response. To quantify these interactions, a unified cyber–physical modeling framework was developed, achieving predictive accuracy with coefficients of determination R^2 = 0.9174 (state model) and R^2 = 0.9329 (regression model). This framework integrates communication-layer metrics, system resource utilization, and electrical parameters to estimate attack intensity and predict instability. The primary contribution of this dissertation is the development and experimental validation of a protocol-aware cyber–physical defense framework that quantitatively links communication-layer disruptions to power-system instability, enabling predictive resilience assessment in smart-grid environments.

Keywords: Cybersecurity, SCADA, cyber-physical systems

Room Location: Electrical and Computer Engineering Department Conference, Room 315D