Modeling and small-signal stability analysis of an islanded DC microgrid with dynamic loads

Motivated by the stability issue under tightly regulated power converters which commonly behave as constant power loads(CPLs) with negative incremental resistance in DC microgrids, this paper studies the detailed modeling and small-signal stability analysis for an islanded DC microgrid. DC distribution shipboard power system is taken as an example which has more challenges over other DC microgrids. The proposed system consists of turbine driven synchronous generator which supplies power to the DC bus via rectifier unit while direct torque controlled induction motor behaves as CPL and resistive load are in the network. Nonlinear model for the studied system is developed and validated by numerical simulation in PLECS. Small-signal stability analysis is conducted to assess the system stability under different operation conditions and design parameters.