Research on Pre-judgment Coordinated Control Strategy of Stand-alone DC Microgrid

Based on the analysis of DC microgrid structure and system operation modes, a pre-judgment coordinated control strategy is proposed for the stand-alone PV/battery DC microgrid in this paper. By considering the change trend of light intensity and state of charge (SOC) of lithium-ion battery, the five operation modes of the system are analyzed, and the control strategies of each unit are designed. According to the energy balance relationship, the photovoltaic system can work in maximum power tracking (MPPT) control and load power tracking control (LPTC) mode. The lithium-ion battery can guarantee the stability of DC bus voltage in microgrid by charging and discharging, and change the working range of SOC under certain conditions, so as to improve the power utilization rate. The load switching control is to ensure the power supply of key loads The stable operation of microgrid can be realized by avoiding frequent switching of load at switching point.The model of PV/battery DC microgrid is built and simulation work is carried out in real-time digital simulator (RTDS). Through the simulation results under different working conditions, the correctness and effectiveness of the proposed pre-judgment coordinated control strategy are verified.