Analysis of microgrid power flow optimization with consideration of residual storages state

Microgrid is a cluster of distributed generation sources, storages and loads that cooperate so as to improve the reliability and quality of the local power supply and of the power system. In this paper we present a power flow optimization of a DC microgrid that consists of photovoltaic array, batteries stack and fuel cells stack with electrolyser, and is connected to the grid via bidirectional power converter. The optimization problem aims to minimize microgrid operating costs and is formulated using a linear program that takes into account the storages charge and discharge efficiency, and considers the residual state of the energy storage systems in the criterion function. Performance of the proposed approach is verified through year-scale simulations based on the actual meteorological, electricity price and consumption data. The analysis performed points out that especially for short prediction horizons it is very important to ensure proper penalization of the residual storages state in the criterion function in order to yield optimum revenue from microgrid operation.