Resilience assessment of the All-Island electrical transmission system under high and low renewable scenarios

This thesis evaluates the operational resilience of the All-Island transmission grid (Ireland and Northern Ireland) under future scenarios of high and low renewable energy penetration. Using DIgSILENT PowerFactory, a validated static power flow model for 2035 was developed based on the 2024 grid, incorporating realistic projections for renewable deployment, interconnector expansion, and demand growth in line with national and European targets. Simulations were conducted for a range of seasonal demand scenarios, distinguishing between high and low wind capacity factors. The results show that high renewable scenarios induce significant grid stress, particularly under low load and high export conditions, with congestion concentrated along major eastward corridors. Summer Valley – High Wind scenarios were identified as the most challenging in both 2024 and 2035, highlighting the limitations of the current transmission infrastructure. The study also investigated the role of HVDC interconnectors in line congestion and enhancing system flexibility. Results confirm that new interconnectors reduce overloads and improve loss profiles, particularly when connected to strong 220 kV nodes. A detailed sensitivity analysis identified the Arklow 220 kV substation as the most technically suitable location for a new HVDC interconnector on the south coast. Key findings underscore the need for targeted grid reinforcements, advanced reactive power management, and dynamic system support to accommodate the future energy mix. The thesis concludes with recommendations for incorporating updated data, dynamic simulations, and techno-economic assessments in future planning studies.