说明：  该文以下垂控制直流微电网为研究对象，首先推导直 流系统的小信号模型，通过特征值分析，研究负荷功率及类 型、变流器下垂系数等参数变化对系统稳定性的影响
(In this paper, the droop control DC microgrid is taken as the research object. Firstly, the small-signal model of the direct current system is derived. Through the eigenvalue analysis, the influence of parameters such as load power, type of load and sag coefficient of converter on the stability of the system is studied.)