| Currently, chaos theory is an important role to receive wide attention in the present studyof nonlinear systems, and has been applied a number of disciplines and engineering fields. Inrecent years, the security and reliable operation have been always the key issues in powersystem, while the power system in the chaotic oscillation will be a serious threat to thesecurity, efficient and stable operation of the power system, and even leading to a voltagecollapse. With the increasing scale of power system, the nonlinear characteristics are moreobvious. Power system will behavior chaos with some parameters or under certain workingconditions, the external performance appears as irregular low-frequency oscillations. So, it isindispensable to study the methods of controlling chaos in order to improve the security andstable operation of power system. In this thesis, a simple fourth-order power system chaoscontrol methods are in-depth studied, and some proper and applicable methods are researchedto control chaos in power system. The main research of this thesis includes followingsections:(1) For analysis and comparison the important methods of chaos control, then give abrief introduction about current chaotic oscillation control methods of power system and pointout the disadvantages of these methods, finally describe the aim and the significance of thisdissertation.(2) From the nature of chaos, analysis of the basic features of chaotic motion system,meanwhile highlights several effective ways to determine whether a system in chaos.(3) Through several typical chaotic power system models analysis, and mainly focus onanalyzing the road to chaos.(4) Power system is a highly complex nonlinear system, bifurcations occur and canexhibit chaotic oscillations leading to a voltage collapse which severely threaten the secureand stable operation of the power system. A novel adaptive controller is proposed based onLaSalle invariable principle, which can asymptotically stabilize an unstable equilibrium points.The system from gradual transition to convergence divergence oscillation until the oscillationsubsides and to explore an effective way for suppression the chaotic power system.(5) Based on the finite-time stability theory, two control strategies are presented toachieve finite-time chaos control. Besides, the problem about how to stabilize unstablenonzero equilibrium point in a finite time is solved by coordinate transformation. Numericalsimulations are presented to demonstrate the effectiveness and robustness of the proposedschemes. |
