Improvement of power system stability using multivariable excitation control

AbstractImprovement of power system stability is the most important issue of generator excitation control. The combination of thyristor excitation with ΔP‐PSS is usually applied to recently installed very large turbogenerators. This power system generator (PSS) is not always effective for wide‐range operation of generators or for various changes of power system line impedance. The application of the optimal control theory, especially the multifeedback signal resulting from the Riccati equation has been studied and reported in many papers. These papers, however, do not clearly describe how to set performance index values and the studies reported in them also use inadequate signals. This paper presents a method to set the performance index values to make adequate feedback signals for selecting actual control on the application of the Riccati equation. Further, the developed PSS using multifeedback signals is applied to actual very large turbogenerators after confirming the performance of effective damping for power oscillation.