VARIABLE STRUCTURE POWER STABILISER TO SUPPLEMENT STATIC-EXCITATION SYSTEMS.

The small-perturbation dynamic stability of a single machine with unsupplemented excitation system has been explored by means of eigenvalue analysis. The study has explored a variety of machine loadings. A power stabilizer to supplement the excitation system has been considered. An attempt has been made to determine the optimum settings of the stabilizer adjustable parameters in conjunction with the minimum of a performance criterion. Numerous (140) cases covering a wide range of real- and reactive-power loading were investigated. The optimum stabilizing signals obtained in each case were tested on the system. It was found that the variable-structure stabilizer is effective and provides significantly more damping than a fixed-structure stabilizer, at load points away from the fixed-structure design point.