Direct Interfacing of Admittance-Based Aggregated Models of Converter-Interfaced Resources in Nodal Analysis EMT Simulators

Converter-interfaced resources (CIRs) are widely integrated into power systems. Thus, there is an increasing need to simulate such systems more efficiently in electromagnetic transient (EMT) simulators. This paper proposes a direct interfacing method for an admittance-based aggregated model (DI-ABAM) of grid-following CIRs to enhance time-domain simulation efficiency in nodal analysis-based EMT programs (EMTP). First, a transfer-function-based ABAM for dispersed CIRs, including their collector lines and any impedance/admittance-based model of system components, such as loads, is developed. Then, the resultant transfer functions of the aggregated model are discretized and formulated as a Norton equivalent, whose conductance matrix and history terms are incorporated into the overall network nodal equation to achieve a simultaneous EMTP solution. This new directly interfaced ABAM permits large simulation time steps, further reducing the aggregated models’ computational burden while maintaining good accuracy. The accuracy and computational benefits of the proposed DI-ABAM are validated through simulations in PSCAD.