POWER SYSTEM SMALL SIGNAL STABILITY AND MAXIMUM LOADABILITY

This paper presents an efficient method for power system maximum loadability assessment considering small signal stability. Conventional methods are based on accurate load flow solutions and calculation of all the system eigenvalues. The proposed method uses appropriate equivalents to reduce the computation time of load flow solution and also applies a special approach to find only the dominant modes. Hence, the computation time is reduced considerably with respect to conventional methods. The approach uses the REI-Dimo equivalent of the network for the load flow solution of the different operating points by simulation rather than calculation of a sequence of successively deteriorated power flow cases. Meanwhile, instead of calculating all the eigenvalues, only dominant ones are evaluated by using the S-matrix method. The algorithm also considers practical aspects of the power systems, so it does not perform the calculation for the cases where the maximum loadability is more than the maximum units generation. Since the approach quickly identifies the distance a power system state is from small signal instability, it could be applied as a valuable aid for monitoring stability in new system control centers.