A Stability Improvement Method of DC Microgrid System Using Passive Damping and Proportional-Resonance (PR) Control

Abstract

Sustainable energy, such as sunlight and wind energy, that comes from sources that do not need to be replenished has become important. Accordingly, the importance of the design and stable management of DC microgrids is also increasing. From this point of view, this paper analyzes the interaction between source and load converters constituting the DC microgrid using the derived mathematical input and output impedances models. This paper proposes a stability improvement method using the analyzed result. The method focuses on the presence or absence of input and output impedance overlap using Middlebrook’s stability criteria. To verify validity of the proposed method, a case study with three damping methods is conducted: (1) RC parallel damping with PR controller, (2) RL parallel damping with PR controller, and (3) RL series damping with PR controller. Additionally, the frequency domain characteristics and the Nyquist stability are analyzed using MATLAB, and simulation verification is conducted using PSIM. Through the analysis and simulation results, we confirm that the stability of the DC microgrid can be improved by applying the proposed method. The passive damping method analyzed in this paper is applied to an installed power converter, where it is possible to ensure the stability of the DC microgrid.