A Novel Dynamic Phasor-based Mathematical Framework for Hybrid AC/DC Power System Simulation

Modern power systems with high penetration of inverter-based resources (IBRs) exhibit fast dynamics and complex harmonic interactions that challenge conventional modeling tools. Electromagnetic transient (EMT) simulations offer high fidelity but are computationally expensive for large-scale or system-wide studies, whereas phasor-domain models neglect harmonics and higher-frequency effects. This paper introduces a dynamic phasor-based framework that provides multiple rotating dq reference frames, thereby enhancing harmonic capture in power system simulations. The method captures fundamental and harmonic dynamics while integrating with existing small-signal analysis tools or control design methods through state-space. The proposed approach is validated through simulations of a modular multilevel converter (MMC) station in Matlab/Simulink, demonstrating accurate reproduction of high-frequency (up to 10 times the fundamental frequency) dynamics and interactions compared with EMT results. The framework achieves EMT-level accuracy, offering a practical tool for the analysis of IBR-rich power systems.