Interactions between, and effectiveness of, power system stabilizers and FACTS device stabilizers in multimachine systems

In this paper it is shown that interactions occur between stabilizers in multimachine power systems, the stabilizers being Power System Stabilizers (PSS's), FACTS device stabilizers (FDS's) or both. The interactions, which are identified and quantified, may enhance or degrade the damping of certain modes of rotor oscillation. In particular, interactions between PSS's are found to adversely affect the damping of inter-area modes. The analysis of interactions also provides a practical means for quantifying and assessing simultaneously the relative effectiveness of both PSS's and FDS's in damping the rotor modes of oscillation. This is achieved using a stabilizer damping contribution diagram. A theoretical basis is given for the analysis of interactions and the effectiveness of stabilizers; the practical significance and applications are illustrated using a case study on a 3-area, 400 state system having 28 generator groups and a number of FDS's, For systems of more than 600-700 states the modified Arnoldi method is used for eigenanalysis-based calculations.