Optimal sizing of a hybrid mini-grid considering the fuel procurement and a rolling horizon system operation

Hybrid mini-grids are promising solutions to foster the universal electricity access in developing countries. While renewable sources, possibly combined with energy storage devices, help in reducing the environmental impact and the operational costs of electricity supply, a backup diesel generator can increase the continuity of service when RES are not available or very discontinuous. The fuel procurement can be a serious issue in rural areas, due to lack of good infrastructures, combined to long distances existing between the mini-grid and the fuel station; however, this aspect is usually disregarded in designing the mini-grid. Moreover, the traditional sizing of rural mini-grids is based on simulating simple operational strategies. Rolling horizon strategies can be more efficient since the system is redispatched also infradaily, thus leading to possible reductions of operational costs and load curtailment. The present paper proposes a novel probabilistic technique for the optimal sizing of a mini-grid, considering both the fuel procurement issues and a short-term rolling-horizon scheduling of resources. This method is applied to a system composed by a photovoltaic plant, a lithium battery, a diesel generator, and a fuel tank, minimizing the net present cost of the system over the project lifetime. A numerical case study is discussed.