OUASIPERIODIC (QP) OSCILLATIONS IN ELECTRICAL-POWER SYSTEMS

The occurrence of quasiperiodic (QP) oscillations in power systems, a phenomena hitherto unknown, was first experienced in the French grid w hen attempting to energize an unloaded transformer at the end of a lon g transmission line, There are no simple analytical tools available to study conditions for the occurrence of QP oscillations. In this paper , the conditions necessary for the occurrence of quasiperiodicity are shown by solving the system equations using the method of harmonic bal ance, It is shown that QP oscillations will occur due to the severity of magnetizing nonlinearity of the transformer core, It is also shown that if core losses are high, only frequency locked oscillations can o ccur. The results are confirmed by numerical solution on the original set of differential equations. Copyright (C) 1996 Elsevier Science Ltd .