Neutral Directly Grounded System Ferroresonance Overvoltage Chaos Control And Inhibition Of Research

This thesis takes the connection of110-kV transformer substation for example, obtains the criterion of ferroresonance ovevroltage in the neutral grounded power system with the mothod of eliminate anlysis. And ferroresonance’s chaotic characteristics are studied by the nonlinear dynamics teroey. Take its own nonlinear characteristics in consideration; it explores some related chaotic controllers.Firstly, according to the ferroresonance ovevroltage mathematical model, the chaos parameter of ferroresonance ovevroltage is obtained with eliminate anlysis and combines the phase plane, Poincare section, Lyapunov exponent and fraction dimension in the nolinear dynamics to get the chaotic characteristics when the ferroresonance happens. They are validated by the MATLAB simulation.Secondly, in order to control the overvoltage when ferroresonance hanppens, three methods used in chaos are reseached with the system’s own nonlinear characteristics.They are called delayed feedback control, backsteepping and fuzzy control. In the design of the delayed feedback controller, we take searching optimization method to confirm the delayed time τ and Pyragas method that is calculating the Lyapunov exponent to determine the feedback factor K. The delayed feedback controller makes the transfer of chaotic state to expected period orbit relized in the ferroresonance system and carried it through simulation. Based on the understangding of backsteepping controller, the ferroresonance system is divided into two subsystems, and we designed different V functions for them. With Lyapunov direct method the backstepping controller is completed. It makes the transfer of chaotic state to expected constant and period orbit relized in the ferroresonance system and carried it through simulation. Based on the thorough understanding of fuzzy control, the ferroresonance system is taken into fuzzy process, wirh the parallel distributed compensation the fuzzy controller is accomplished and the improvement is advanced. The simulation results show that the performances of all three controllers are satisfied.Finally, the avantages and disadvantages and the impvoments are pointed out according to the comparing and anlysis the performances of the three contrllors. It also provides a certain reference for the further reseach.