Impedance-Based Stability Analysis of DC Distribution Systems with Complex Network

The impedance-based stability analysis method is widely used in DC distribution systems. However, most existing methods are based on the one-dimensional impedance transfer functions and overlook the system's complex network. This paper investigates the small-signal stability of DC distribution systems with complex networks. First, the small-signal equivalent circuit model of the system is established and the closed-loop transfer function from all input variables to bus node voltages is derived. Second, based on the control theory of multi-input multi-output systems, two system-level stability criteria based on admittance matrix sum and equivalent loop gain are proposed, respectively. Finally, a typical DC distribution system consisting of four nodes and four converters was designed for case analysis and simulation, and the results show the correctness of the proposed stability criteria.