LOW-ORDER NETWORK EQUIVALENTS FOR ELECTROMAGNETIC TRANSIENTS STUDIES

Network equivalents can be used to represent parts of a power system t o reduce the complexity and the computation time during the simulation of electromagnetic transients. The goal is to simplify the representa tion while preserving the accuracy of transients in the remainder. Fir st, equations for the subnetwork of interest are stated in the frequen cy domain using network admittance functions. For cases of practical i nterest, it is shown that these can be approximated by low-order ratio nal functions using an existing, proven optimization technique of cont rol system engineering. Finally, the Electromagnetic Transients Progra m (EMTP) has been modified to permit the direct representation of such equivalents, which can be efficiently used for switching surge and fa ult studies. A detailed numerical example illustrates accuracy and eff iciency of the new procedure.