Energy management strategy for a renewable-based public electric-bus microgrid: peak load reduction and PV generation use-optimization

Abstract

This thesis proposes an energy management strategy for an electric public transport microgrid scenario comprising a fast-charging station (rated at 300 kW), a photovoltaic (PV) system (rated at 134 kWp-100kW inverter) and a second-life battery system (rated at 84kWh - 80kW maximum power discharge). This microgrid is used by the bus fleet of line 9 in the city of Pamplona, Spain. The microgrid is connected to the utility grid allowing for the control of the power exchange between them through the battery and its control program. The proposed strategy uses the battery state of charge (SOC), the charging station power demand and the PV power production as input parameters for the control strategy. The simulation of this system is performed on Matlab using a one-year dataset using four energy management strategies. The final strategy results in a reduction of the peak power demand of the charging station by 80 kW consistently throughout the year (35% of the total daily peaks). Roughly one third (32%) of the energy needs of this charging station are expected to be met by energy produced from the PV system. The average battery SOC is maintained at around 90% and the battery never discharges below 50% SOC.