Stability analysis of a DC microgrid with master-slave control structure

Nowadays there is an increasing interest on dc microgrid for its higher energy efficiency and higher reliability as compared to the ac system. This paper addresses the stability problem in a dc microgrid with master-slave control structure. Considering the discrete sampling and control algorithm in a digital system, the small-signal models of this dc microgrid have been derived in the z plane. Eigenvalue analysis results show that the system stability and transient response will be affected by the variation of the dc load parameters, the number of slave distributed generations (DGs), and the type of dc load. A centralized oscillation suppression controller, which is composed of a proportional compensator followed by a bandpass filter, is proposed to overcome the unstable oscillations caused by different eigenvalues. The validity of the proposed approach is confirmed by simulations.