MULTIPORT EQUIVALENCING OF EXTERNAL SYSTEMS FOR SIMULATION OF SWITCHING TRANSIENTS

A multi-port external system equivalent model to simulate switching tr ansients is developed based on direct time domain techniques, as oppos ed to the currently available models based on frequency domain methods . The model comprises discrete-time filters, which are built using the external system's response at each of the M ports to a multisine exci tation signal and solving a system identification problem. At each por t, the filters obtained are converted into an equivalent Norton circui t consisting of M current sources (in parallel). A unique feature of t he model is that it explicitly incorporates the travel time delay betw een the ports. The complete M-port model, having M decoupled equivalen t Norton circuits, is easily integrated into the discrete-time represe ntation of the study subsystem. The proposed model is validated by sim ulating the line energization and post-fault transients in a study sub system connected at two ports to an external system.