Stability Analysis of DC Microgrids with Constant Power Load under Distributed Control Method

DC microgrids are becoming popular as effective means to integrate various renewable energy resources. Constant power loads (CPLs) may yield instability due to the negative impedance characteristic. This paper analyzes the stability of the DC microgrid in presence of CPL. Distributed generations (DGs) are controlled by using a distributed controller which aims at current sharing and voltage recovery. For simplicity, a reduced order model is derived on the fundamental of neglecting the transient state of the DC/DC converter. The purpose of this paper is to analyze stability conditions and give the suggestions to design control parameters. The stability conditions are obtained by using inertia theorem. Moreover, this paper makes a further detailed research based on the existed theorems. Simulation results are provided to verify the effectiveness and validity of the proposed theorem.