Along with the increasing penetration of power electronics in distribution networks

small-signal stability issues

such as wide-band oscillations

have become increasingly severe. This paper focuses on a power-converter-based flexible interconnection system for distribution networks and investigates its small-signal stability. Firstly

based on the established small-signal impedance model of the DC side

Million's Theorem is used to obtain the parallel equivalent circuit. Subsequently

the Nyquist criterion is applied to assess stability and determine the corresponding stability boundary. Subsequently

based on a sensitivity analysis of the DC-side impedance transfer function

a quantitative sensitivity index is constructed using the H∞ norm. Furthermore

a quantitative index for multi-parameter coupling is established using the Hessian matrix. The coupling effects among control parameters are classified as synergistic and antagonistic

providing a scientific basis for adjusting control parameters. Finally

frequency scanning is performed on the DC-side impedance of the studied system to validate it. Simulations are conducted to verify the stability region

first-order sensitivity coefficients

and multi-parameter coupling results

demonstrating the effectiveness of the proposed analytical method.