To improve the load capability, operating efficiency and power density of the DC distribution power systems (DDPSs), the application of dual-terminal structure (DTS) composed of multiple DC transformers (DCTs) is widely expanding. Focusing on the cascaded stability, the active damping methods for DCTs are widely researched to suppress the oscillation. However, whether DDPSs composed of the DCTs controlled by active damping methods are still stable is mysterious. This paper builds an impedance model for a DTS DDPS and evaluates the stability of a DTS DDPS composed of all-active-damping-controlled DCTs based on the Nyquist Criterion. Analyzing and simulating results show that a DTS DDPS is stable with a high margin when composed of all-active-damping-controlled DCTs, and it also has fast dynamic speed and good balance ability. This paper provides theoretical support for the construction of the DTS DDPS.

Dual-terminal structure (DTS),DC distribution power systems (DPSs),multiple DC transformers (DCTs),stability evaluation