Co-ordinated design of multimachine power system stabilisers based on damping torque concepts

The author employs damping torque concepts associated with frequency response analysis, to consider the co-ordinated design of power system stabilisers (PSSs) in multimachine power systems. The aim of the proposed approach is to provide, through the action of the stabiliser, an electrical damping torque proportional to speed perturbations, i.e. ΔP_ei(s)=D_i Δω_i(s). The stabiliser network is designed to compensate for the phase lag and gain in the machine/system transfer function ΔP_ei(s)/Δv_ri (s). The stabiliser gain D_i is co-ordinated, in the first instance, so that the damping effect is distributed among those machines fitted with stabilisers in proportion to their ratings. The damping performance of a sample power system with PSSs installed is shown to be comparable to that for a multimachine system without PSSs in which a pure damping torque is introduced artificially in the transfer function block representing shaft dynamics