A Framework for Frequency Domain Analysis of Grid-Forming and Grid-Following Converters

This paper presents an automated framework for frequency domain analysis of grid-forming and grid-following converters. The interface is designed to facilitate parameter variations and initialization of operating points in a highly flexible manner. First, the nonlinear simulation model is automatically driven to selected operating points. Then, using built-in linearization capabilities, the model is linearized around these operating points to generate the corresponding frequency responses. These responses are subsequently examined with respect to passivity criteria, enabling a systematic stability assessment that does not rely on labor-intensive analytical derivations. In addition, the resulting frequency domain data from several representative operating points qualitatively yield the same results as the analytically derived frequency responses from existing literature. The close agreement between the automated and analytical results indicates the accuracy of the linearization procedure. In general, this automated method simplifies the analysis workflow and also provides a tool for evaluating the stability of converters under various operating conditions.