Hybrid mini-grid power system for electrification of remote and rural locations in Fiji

Abstract

Hybrid mini-grids appear to be one of the most promising technological options for electrifying remote and rural areas. However, there are still important questions, technical and non-technical, regarding their capabilities and appropriate application. This thesis focuses on two key opportunities to improve hybrid system; advanced load modelling with the concept of load prioritization, and system design to permit relatively graceful degradation of hybrid mini-grid performance when some of the component technologies fail and cannot be immediately repaired. More broadly, the thesis has also sought to identify some wider challenges of successful project implementation in the particular context of Fiji. This thesis then presents a detailed study of load modelling carried out through consultation with authorities in Fiji and some small scale load surveys at the village level. It proposes establishing a hierarchy of load priority to ensure that the hybrid system continues to supply to most important loads should its capabilities decline due to failure or unexpected events. A widely used software design tool is then applied to design appropriate hybrid systems to meet such loads. However, standard performance metrics from this tool are extended through the use of failure mode analysis to better understand the potential resilience of different designs. A detailed literature review and targeted consultations with a range of Fijian stakeholders were undertaken to better understand options for addressing the non-technical challenges of project implementation. The research suggests some key findings: different hybrid systems can have different resilience to technical failures and other unexpected events and simple least cost performance optimisation may not always be appropriate; load prioritization can help secure delivery of the most essential energy services at times of partial system failure; and successful stakeholder engagement, system design, implementation, operation and maintenance all have a key role in achieving sustainable outcomes. In conclusion, this research argues for the use of multi-objective design criteria for the design of hybrid mini-grids. As such, the study recommends that research and development should become an integral part of the evolution of hybrid mini-grids in remote and rural applications.