Edinburgh Napier University

  Many developing countries suffer from unreliable grids and rolling blackouts on a daily basis. Losing electricity in healthcare facilities can be detrimental to human life and the required health services. Thus, it is often necessary to keep critical loads operational even if the grid experiences a blackout. Such support is usually provided using battery storage or diesel generators. In the system design phase, it is often unknown how the priority-based load management will impact the battery life, sizing of the optimal battery, or operational cost in the long run. This paper presents a comprehensive analysis of a priority load management strategy for healthcare facilities in areas of highly unreliable grids. A grid-connected battery backup system is used for the evaluation. To operate the system, a priority-based dispatch algorithm is developed, which classifies medical loads into three tiers based on their criticality. Synthetic medical facility load profiles and blackout patterns are constructed to test the algorithm. The battery model was enhanced with the introduction of aging calculations spanning multiple years. It was found that the priority-based algorithm improved the reliability served to the most critical loads at the expense of the least critical. The load priority strategy slowed the battery pack degradation over time and reduced the number of replacement cycles, which is financially favorable in the long run. Finally, some insights for designing such a backup system are provided.