Local and regional microgrid models to optimise the design of isolated electrification projects

Wind-photovoltaic stand-alone electrification systems are a suitable option to provide electricity to isolated villages, in the right context of rural areas far from the national grid. Many initiatives promote electrification projects in rural areas spread across a territory; generally considering each village independently, implementing local microgrids. However, for the case of several neighbouring villages, a regional microgrid connecting them together may reduce costs. Determining the optimal design requires solving complex optimisation combinatorial problems to explore possible generator combinations and microgrid connections. In order to find the solution, a two-scale procedure is proposed: first, a local-scale mathematical model is developed to design a microgrid for each village; and then, a regional-scale model is proposed to design a microgrid connecting the villages together. Both models minimise the lifecycle costs and optimise supply quality, while considering the electrical requirements of end-users and solving for the location of equipment and the microgrid structure. For its validation, the two-scale procedure is considered for five small villages in La Rioja (Northern Spain); according to an Administration request to promote electrification for rural development. As a result, an optimised regional microgrid is proposed, supplying the five villages together, using medium voltage lines between them and low voltage lines internally, with generators centrally located on a windier mountain peak.