A Multiple Time-Step Formulation of Frequency-Dependent Network Equivalents

This paper describes a novel approach for electromagnetic transient simulations of frequency-dependent network equivalents featuring variable time-step length along the simulation run. This demands an inclusion of an intermediate step allowing reinitialization of state variables without a need to modify the structure of companion networks adopted by EMTP-like programs for time-domain simulations. Besides keeping the accuracy of the classic EMTP modeling, the proposed formulation provides a sensible gain in the overall computation time and also a smooth transition regardless of the change in time-step length. This approach provides a more efficient realization of admittance-based models is achieved in a straightforward way, and the computational burden is considerably reduced without a significant loss of accuracy. © 2018, Brazilian Society for Automatics--SBA.