Delay Margin Computation of Generator Excitation Control System with Incommensurate Time Delays Using Critical Eigenvalue Tracing Method

This study investigates the effect of incommensurate time delays on the stability of the generator excitation control system. Unlike studies in the literature, the delay-dependent stability analysis is performed for cases where time delays in the feedback and feedforward loops of the generator excitation control system are independent of each other. The delay margin values are calculated by using the eigenvalue tracing method. The technique obtains critical eigenvalues on the imaginary axis in line with the eigenvalue loci of a transformation matrix in order to obtain stability regions in a two-dimensional delay space. It is found that the stability of the generator excitation control system deteriorates for delays outside the stability region. The accuracy of stability boundary is verified by time-domain simulations and Quasi-Polynomial Mapping Based Rootfinder (QPmR) algorithm.