Prof. dr. Vladimir Terzija

The increasing digitalisation of modern power systems, together with their growing operational complexity and dependence on wide-area monitoring and control infrastructures, has created new pathways through which cyberattacks may initiate or exacerbate cascading outages. This presentation investigates the role of System Integrity Protection Schemes (SIPS) in mitigating cyber-attack-induced disturbance propagation, with particular emphasis on controlled islanding as an emergency corrective strategy. A conceptual distinction is first established between blackouts and cascading outages: whereas blackouts represent the final system-level consequence in the form of widespread interruption of supply, cascading outages are understood as the underlying dynamic process whereby an initial disturbance triggers successive dependent outages across the network. The evolution of such processes is strongly conditioned by the pre-disturbance operating point, system topology, and prevailing uncertainty. Particular attention is given to the role of Wide Area Monitoring Systems (WAMS), which rely on phasor measurement units (PMUs), synchrophasor data streams, and supporting communication architectures to provide near real-time visibility of power system dynamics. Although these technologies significantly enhance situational awareness and disturbance detection capabilities, they also enlarge the cyber-physical attack surface of the grid. The presentation identifies several representative categories of cyberattack, including false data injection, malicious reprogramming of remote terminal units, and compromised application software. Such attacks may corrupt measurements, bias state estimation, distort decision-support functions, and ultimately induce inappropriate or delayed control actions under stressed operating conditions. Against this background, the presentation examines the general mechanism of cascading blackouts, including preconditioning factors, initiating disturbances, cascade development, and post-disturbance restoration. Controlled islanding is then considered as a deliberate SIPS action aimed at interrupting the propagation of instability by partitioning the system into electrically coherent and operationally sustainable islands before uncontrolled separation occurs. Comparative simulation studies are used to illustrate the system response under identical initiating events with and without intentional islanding. The results indicate that, although islanded subsystems may not always remain fully stable, controlled islanding can significantly reduce cascade extent, preserve service continuity in retained areas, and improve overall resilience relative to uncontrolled cascading development. The presentation concludes that cyberattacks should be treated as credible initiating mechanisms for cascading failures in contemporary cyber-physical power systems. It further argues that enhanced understanding of cascade dynamics, coupled with the development and validation of practical emergency control strategies such as controlled islanding, is essential for strengthening system resilience and advancing the operational readiness of SIPS-based mitigation solutions.

Keywords: Cascading events, blackout prevention, SIPS