| As a complex nonlinear system,the power system has the characteristics like strong coupling and multi-parameters,and exhibits many nonlinear electromechanical oscillation dynamic behaviors.Due to various unexpected events and uncertain factors,the parameters of the power system would oscillate continuously and irregularly,which results in occurring chaos in the operation of the system.In severe cases,it can lead to instability and even collapse of the power system.In order to ensure the safe and stable operation of the system,it is necessary to consider some disturbance factors to conduct a study on the mechanism of chaotic oscillation in the power system and suppress it.At the same time,it provides some reference data for online monitoring and accident handling of the power grid.This paper establishes generators model,dynamic load model,and network model in power system.In addition,considering the node voltage amplitude and phase angle of the generator and power system,a four-dimensional power system dynamics model is obtained.With load reactive power and mechanical input torque as bifurcation parameter variables,a four-dimensional mathematical model of a twoparameter power system is established.We will obtain the maximum Lyapunov exponent of the two-parameter system by using Jacobi matrix method through numerical simulation to acquire the parameters’ range of system chaos.Then,the four-dimensional mathematical model of the one-parameter power system with load reactive power and mechanical input power as bifurcation parameters is taken respectively for numerical simulation and analysis to obtain the maximum Lyapunov exponential diagram,bifurcation diagram,timing diagram,and phase attractor diagram.By exploring the mechanism of chaotic oscillation in power system and the character of chaos,we have found that the chaotic oscillation belongs to mixed oscillation in different frequencies.Based on the characteristics of chaotic oscillation in power system that we have studied in this paper,a sliding mode controller based on the exponential approach law with four variables is designed to suppress the chaotic oscillation in twoparameter four-dimensional model of the power system.With the controller we have designed,the system can work stably at the target operating point during chaos and the bifurcation parameters’ range of chaos.Further,the controller’s robustness is verified by simulation analysis. |
