Small-signal stability analysis and participation factor identification for multi converter DC microgrids

With the rapid growth of distributed renewable energy sources, the dynamics and complexity of DC microgrid systems have increased, posing challenges to the small-signal stability of systems. This paper primarily investigates the small-signal stability issues of the Multi Converter DC Microgrid (MCDCM) and utilizes impedance analysis to obtain the negative feedback model of the system. To further enhance system stability and identify potential instability factors, a novel method based on the generalized Nyquist criterion is proposed for identifying participation factors. This method allows for the derivation of sensitivity curves to quantitatively analyze the impact of parameters on stability. Finally, a microgrid system with six converter clusters is constructed, and an analysis is conducted using participation factors such as the bus capacitance and energy storage droop coefficient. The feasibility of the proposed schemes is verified through frequency domain analysis and RT-LAB hardware in the loop experiments. This study provides a theoretical basis for the stable operation of microgrids and the identification of participation factors.