Small-Signal Analyses Using Analytical IBR Models and Frequency-Dependent Thévenin Equivalents

Abstract

This paper investigates whether component-level studies can capture additional interactions through Small Signal Analysis (SSA) when the network connected to the Voltage Source Converter (VSC), typically modeled as a simple Thevenin Equivalent, is a more complex IBR-based network. The research investigates cases ranging from basic analytical to an IEEE 9-Bus EMT model, with and without Inverter-Based Resources (IBRs), synthesized as State-Space elements. The study identified that spurious poles at 50Hz related to dq-frame conversion can hinder the accuracy of participation factor analysis. A potential approach involves a two-step process: first, applying Henkel reduction to remove most spurious poles, followed by manual elimination of any remaining ones.