Shifted-frequency analysis for EMTP simulation of power-system dynamics

Traditional power-system dynamic simulation tools make a number of simplifying assumptions to speed up computations; thus, they can only capture snapshots of the system operation, ignoring the dynamics between states. This paper applies the shifted-frequency-analysis (SFA) theory to the Electromagnetic Transients Program (EMTP) simulator in order to efficiently obtain the time-domain simulation results in the neighborhood of the fundamental frequency without making quasi-steady-state or other simplifying assumptions. The SFA-based EMTP simulator can provide dynamic-phasor results that accurately trace the evolution of the system state in three-phase power systems. Dynamic phasors provide envelopes of the time-domain waveforms and can be accurately transformed back to instantaneous time values. Test cases have verified the usefulness of the SFA-based dynamic simulation method.