A comparison and simulation study of nonlinearly designed robust controllers for power system transient stability

In this paper, the robust mechanical and excitation control algorithms, together with power system stabilizer (PSS) are studied and compared. In light of the fact that theoretical results on Lyapunov stability have been established for these control algorithms, effort has been concentrated in this paper on comparisons between these algorithms and the conventional exciter and the PSS. It is shown through simulations on the 39-bus New England system that robust control algorithms are very effective in improving power system transient stability and that their combination shows a much better performance compared to that under any one of them. It is also through the simulation study that the problem of how to select control gains is addressed. In fact, it is shown that "optimal" gains exist and that they are not large.