Strategic operational management of GB National Energy Transmission System during extreme events: Storm Éowyn

Britain (GB) national electricity transmission system (NETS). These events are now becoming prevalent, and they pose major challenges for network system operators. On January 21, 2025, the UK metrological office issued advanced weather warning (yellow warning) for very strong wind for Scotland and Northern England and naming the event Storm Éowyn, expected to make landfall on January 24. Weather office provided continuous updates and upgraded it to red for parts of Scotland, signalling severe winds with the potential for property damage and power outages while other areas remained under amber warnings.

This paper presents the strategic operational planning and response of NESO to this high impact widespread storm, which caused concurrent transmission and distribution line faults across

Northern Britain. This resulted in power loss for around hundred thousand homes and severe logistical bottlenecks due to widespread fallen trees & debris. The strategic planning details about proactive response & reserve and inertia procurement on the day, network topology adjustments and multi-stakeholder coordination. While another section deals about real-time impact of storm on transmission system and mitigating actions taken by control room. The paper specifically analyses critical incidents which tested the resilience of the transmission system. Key findings highlight the success of pre-emptive network topology adjustments in minimising cascading failure risk and the importance of simulator-based training in fostering rapid decision-making. The paper concludes with recommendations for mandatory integrated multi-agency simulation exercises, and the adoption of advanced computational tools for predictive network assessment, ensuring future operational strategies can withstand the escalating severity of climate change-driven extreme events.