Three-dimensional full-wave transient analysis of switches and faults using a method of moments solution of the electric field integral equation

Abstract

Three-dimensional full-wave electromagnetic transient (EMT) analysis of switches and faults is shown to be possible in the time domain (TD) from numerical solutions of Maxwell's equations in the frequency domain (FD). The electric field integral equation is solved by the method of moments for the initial fault or switch condition (open/closed). The problem is then cast into subsequent FD problems based on the principle of superposition. At each stage, the FD solution is converted into TD and modified by appropriate functions selected to enforce the desired switch operation (closing/opening) in the next stage. This is also applicable to applying and clearing faults at desired times. In order to navigate between the TD and FD solutions, the fast Fourier transforms are applied and a systematic procedure for obtaining a numerically convergent solution is introduced. For slow transients, results exhibit excellent agreement with simulations obtained from an EMT-type program. However, when faster transients are considered (e.g. in gas-insulated substations), the proposed method is shown to provide more realistic results than those computed by the conventional EMT simulations.