An investigation into the effects of high renewable energy penetration in the Pacific Islands: A case study of Niue

Abstract

The transition from diesel-dependent isolated grids to hybrid renewable energy systems presents both technical opportunities and operational challenges for Pacific Small Island Developing States (SIDS). This study presents a quasi-dynamic simulation analysis of Niue's power grid under five progressive renewable energy integration scenarios, modelled using DIgSILENT PowerFactory. While the existing network infrastructure is demonstrated to be adequate for all modelled transition scenarios, the progressive introduction of variable renewable energy sources fundamentally alters grid behaviour, shifting from stable and predictable diesel dispatch to an increasingly dynamic system. The study identifies that Battery Energy Storage Systems (BESS) are critical enablers of diesel displacement, but their effectiveness is highly sensitive to PV system sizing and diesel operational practices. Prolonged low-loading of diesel generators under high renewable penetration is shown to pose risks of wet stacking with direct implications for asset management in small island utilities. The imposition of a minimum diesel loading constraint, while necessary for generator health and frequency stability, is found to saturate storage capacity and necessitate renewable curtailment, highlighting a fundamental tension in hybrid system operation. Additionally, the progressive reduction of synchronous generation raises considerations regarding grid inertia that warrant dedicated frequency stability investigation. The findings offer transferable insights for renewable transition planning across Pacific SIDS with similar isolated grid contexts.