DC Microgrids for Industrial DC Application: Focus on Energy Management and Storage Optimization

This paper deals with a DC microgrid powered by a photovoltaic (PV) system, supported by a Battery Energy Storage System (BESS) to supply DC loads of specific industrial processes and tertiary applications. These microgrids are of interest for industries characterized by high energy consumption (energy-intensive). The relevant objective is to reduce energy import from the grid, lower energy procurement costs, and minimize current ripple affecting the DC loads. The system includes an interface with the AC grid through a bidirectional DC/AC converter in order to export surplus of PV energy to the grid and guarantee electricity supply when needed. It also integrates a charge controller to manage the BESS system using a dedicated energy management system (EMS). This study focuses on determining the optimal BESS capacity to maximize the Net Present Value (NPV) of investments-originated savings. Industrial electricity load profiles, PV generation data derived from 18 years of average hourly irradiation, and three years of electricity price profiles are used for the optimization inputs. BESS power is optimized over a one-year period to minimize grid energy exchange, with annual cost curves used to maximize the NPV. In addition, an optimization algorithm implemented in the EMS useful for the daily scheduling of the system is also proposed.