Analysis for Oscillation in Microgrid Considering Impedance and Reshaping Control for Suppression

VCS-based system is a common form of AC/DC interconnected microgrid due to its flexibility in power supply and control. However, the line impedance between DC bus of microgrid and DC terminal of VSC can not be neglected, which significantly deteriorates system stability. This article focuses on the input impedance of VSC seen from the DC side and the output impedance of rest part of VSC-based system to analyze the stability of the system. Furthermore, a feedforward compensation impedance reshaping method is proposed to enhance stability margins when power flows back through VSC. Simulation results confirm the effectiveness of this proposed method.