Analysis of Power System Failure Occurred on 09 February 2025 in Sri Lanka’s Power System

This paper discusses the total power system failure that occurred in Sri Lanka on 9 February 2025 and reviews the key technical aspects intended to ensure the smooth and stable operation of the power system. The study examines the performance of (a) protection relays, (b) the Under Frequency Load Shedding (UFLS) scheme, (c) frequency-controlling machines, and (d) inverter-based solar and wind power plants during the disturbance. The analysis identifies deficiencies in system response, particularly in the coordination of protection systems and the behaviour of inverter-based generation under abnormal grid conditions. Based on the findings, the paper recommends the implementation of robust, grid-friendly inverter control settings and the enactment of regulatory provisions to ensure mandatory compliance by all stakeholders. These measures are essential to enhance power system resilience and prevent similar large-scale failures in the future.