DQsym: A MATLAB/Simulink library for dynamic phasor simulation of AC/DC power systems

AC/DC converter–based power systems require modelling tools that can capture dynamic and harmonic behaviour while integrating seamlessly into established simulation environments. This paper presents D Q s y m , an open-source MATLAB/Simulink library for dynamic phasor–based simulation using a unified state-space formulation. Using D Q s y m , multiple harmonic orders are represented through multiple rotating DQ reference frames within a single simulation run. D Q s y m is implemented using standard MATLAB/Simulink functions and masked subsystems, allowing seamless integration into existing workflows. Available components include sources, mathematical operation blocks, state-space blocks, and measurement tools. D Q s y m provides structured numerical outputs and visualization utilities to support reproducible simulation studies. The design and architecture of D Q s y m are described, and an illustrative example based on a single-station Modular Multilevel Converter (MMC) with full control demonstrates its correctness. Simulation results closely match those obtained from conventional Simulink implementations, validating the approach and confirming its suitability for harmonic-capture power system simulation.