Mixed phasor and time domain modelling of AC networks with changeover management

Abstract

Simulation studies on AC electric networks may comprehend periods of quasi-stationary operation and rapid transients. The adoption of a phasor-based approach results in high simulation efficiency, but is limited to the first of the two situations above, while for the second, time domain models are required. For system studies where both situations have to be simulated, a modelling paradigm is thus required that can join the two approaches in all the described components, and by which the simulator of an entire network can be endowed with the capability of moving back and forth from a phasor to a time domain system description automatically, taking care of the proper re-initialisations when necessary. In this paper we propose a possible solution, and apply our ideas by presenting the first nucleus of a Modelica library designed along them. We also show some simulation examples to support the validity and practical convenience of the proposal.