Extensions to Two-Port Network Modeling Method and Analysis of Multiple-VSC-Based Systems

In the impedance-based stability analysis methods, the grid-connected voltage source converter (VSC) is described as a multiple-input multiple-output (MIMO) system, which is also a two-port network. In this paper, a stability analysis method based on the concepts of scattering parameters (S-parameters) and reflection coefficients in the two-port network theory is proposed. Through the use of reflection coefficients, the open-loop gains at each bus can be derived individually. Thus the system with multiple VSCs is characterized as connections of two-port networks with S-parameters. The stability can then be analyzed using the classical stability analysis tool and the relative stability is defined. Experimental results validate the theoretical findings.