A New Energy Management Control Strategy for PV-Battery Hybrid System

Abstract

photovoltaic are limited in terms of available power due to their intermittent nature. Therefore, in order to balance the power difference between PV and load in an islanded DC microgrid, a battery energy storage system should be used. An energy management control technique for a PV-battery hybrid system is examined in this paper in order to meet the load power needs at all moments. In order to minimize the losses, a unidirectional boost converter is utilized to track the maximum power point or curtail power from the PV array to the common DC load. A buck converter is proposed to connect in parallel with boost converter to charging the battery energy storage system; another boost converter is used to control battery storage’s discharge operation. The proposed approach for the power flow load and converters is used to preserve balance of power in the hybrid system, as well as charge/discharge of the battery storage to support the PV panel occurs depending on the PV power generated, state of charging, and the load power requirement. A double-loop control strategy is proposed for each converter taking into consideration the battery’s state of charge, battery charge rate limits, and adjusting operating point for PV array in order to avoid overcharge. Additionally, the control system is implemented without needing for programmatic elements or a state diagram. The proposed control strategy design, analysis, and validation results under several operating scenarios are presented and discussed. This work represents a simple method to make the hybrid system more efficient and reliable.