Modeling and Stability Analysis of DC Microgrid with Photovoltaic and Energy Storage System

The DC microgrid with photovoltaic and energy storage system has become a prevailing trend for new energy. However, the whole system involves a variety of power electronic converter interactions, so it is necessary to conduct system stability analysis. Firstly, the topology and control strategies of the DC microgrid with photovoltaic and energy storage system are introduced, including photovoltaic power generation system and its control, energy storage system and its control, and grid and grid-side converter topology and its control. Secondly, the impedance or admittance of these three units are modeled separately. Next, each unit is equivalent into the corresponding voltage source system or current source system, and the impedance proportion of the DC microgrid with photovoltaic and energy storage system is obtained. Then based on the Nyquist stability criterion, the obtained impedance proportion is used to analyze the impacts of the proportional parameters of the voltage loop of the grid-side converter, the control parameters of the current loop of the energy storage system, as well as the capacity of the energy storage system and the charging and discharging states of the energy storage on the stability of the DC microgrid with photovoltaic and energy storage system.