Optimal planning of multiple distributed generating units and storage in active distribution networks

Traditionally, the energy supply in off-grid communities has relied on diesel generating units based microgrids (MGs) but global environmental concerns and advancements in renewable energy technology are pushing for the transformation of these systems into renewable-based MGs. This transformation is a more complex hybrid system, with dispatchable and non-dispatchable resources, and requires novel planning and design tools to ensure the security of supply in the future. This paper presents a methodology that jointly optimizes the capacities and locations of dispatchable and non-dispatchable distributed generating units and battery energy storage system employed in a stand-alone MG serving conventional residential and electric vehicle charging load. The complex dual optimization problem is solved innovatively in two sequential steps. In the first step, the capacities of solar photovoltaic panels, wind turbines, battery energy storage system, and diesel generator are determined without actually considering the system design itself. While in the second step, a novel and simple methodology is developed which determines the sub-optimal capacities of distributed generation units along with their actual locations in the distribution system. To determine the optimal locations of distributed generation units, we defined a novel factor, losses-voltage-factor (LVF), which ensures reduced losses and better voltage quality. The proposed methodology gives a robust design that not only results in reduced losses and better voltage quality but also have higher reliability. The proposed technique is very practical, which can easily be applied for the planning and design of the practical active distribution networks.