Low‐order network equivalents for electromagnetic transients studies

Network equivalents can be used to represent parts of a power system to reduce the complexity and the computation time during the simulation of electromagnetic transients. The goal is to simplify the representation while preserving the accuracy of transients in the remainder. First, equations for the subnetwork of interest are stated in the frequency domain using network admittance functions. For cases of practical interest, it is shown that these can be approximated by low‐order rational functions using an existing, proven optimization technique of control system engineering. Finally, the Electromagnetic Transients Program (EMTP) has been modified to permit the direct representation of such equivalents, which can be efficiently used for switching surge and fault studies. A detailed numerical example illustrates accuracy and efficiency of the new procedure.