Modeling of DC micro-grid and stability analysis

The average models of various converters and their control systems are established by state-space approach, based on which the small disturbance stability of DC micro-grid is analyzed to obtain the loci of system eigenvalues versus converter control parameters. It shows that, when control parameter increases to a certain value, the real part of eigenvalue becomes positive, i.e. the system becomes instable. The time-domain simulation is carried out to obtain the voltage curves under different control parameters, which validates the practicability of proposed analysis method. It also shows that, within the stable range, the larger the control parameters are, the better the voltage control performance is. It is concluded that, the proper setting of converter control parameters ensures the voltage stability of DC micro-grid.