Identification of Sub/Super-Synchronous Control Interaction Paths Using Dissipative Energy Flow

Sub- and super-synchronous control interactions (SSCIs) are oscillations arising from adverse interactions between inverter-based resource (IBR) controls and the power network. SSCIs often involve multiple frequencies and propagate through complex, interconnected paths, making it difficult for model-based approaches to identify both the sources and the paths of oscillatory energy flow. This paper extends the Dissipative Energy Flow (DEF) method, originally developed for low-frequency electromechanical oscillations, to identify SSCI sources and dynamic interaction paths across multiple frequencies using three-phase voltage and current measurements. The approach operates in the dq frame using dynamic phasors, enabling mode-specific DEF computation from bandpass-filtered signals. An electromagnetic transient (EMT) case study on a meshed network with synchronous generator and type-3 wind farm resources under series-compensated conditions demonstrates the method's capability to distinguish frequency-dependent source and sink roles, including cases where the same resource acts as a source at one frequency and a sink at another. The results show DEF can provide a physics-based and automation-friendly tool for SSCI diagnosis in IBR-rich grids.