Chaotic Power System Control Based On Variable Structure Theory

Power system is a nonlinear system with dynamic behavior.When parameters change,time delay or external disturbance occur in the system,the system will exhibit complex nonlinear dynamic characteristics such as low-frequency oscillation,synchronous harmonic oscillation,chaos and other phenomena.When chaotic oscillation is generated in the power system,overvoltage and overcurrent will be caused,and even lead to the breakdown of the interconnected power grid.The normal transmission of power is impeded,and the normal operation of the power grid will seriously affected.With the continuous introduction of new energy into the power system,the operating environment of the power system becomes more complex,and the local chaos phenomenon of the power grid may evolve into the overall chaos of the power system,thus causing the collapse of the entire system.Therefore,the study of chaos in power system has special significance to maintain the safe operation of power system.Based on chaos theory,the chaos phenomenon of the nine-order power system model is analyzed by means of time domain diagram,bifurcation diagram,system power spectrum diagram and attractor phase diagram in this paper.The variable structure theory is used to design the system controller for the purpose of power system stability.The main contents are as follows:The main parts of the power system are modeled and analyzed,and the nine-order power system model is established;The bifurcation diagram,system power spectrum diagram and attractor phase diagram in chaos theory are used to show the change of operation state of the system caused by the change of uncertain factors,so as to illustrate the process of the system from stable state to chaotic state.The system controller is constructed by sliding mode variable structure theory to control the system from chaotic state to expected value.In order to improve the inherent chattering phenomenon of sliding mode control,a new sliding mode surface is obtained by combining fixed-time sliding mode control with backstepping control to improve the performance of the controller.To consider the impact of external interference on the system,a new sliding mode control method is proposed by combining fixed-time sliding mode and PI control.The observer is connected to estimate the external interference.In order to reduce the time of finding control parameters,Ant lion algorithm is used to optimize the control parameters based on a new objective function.Simulation results show that the proposed control method has good control performance.The variable structure synergetic control is used to design the controller with the advantages of sliding mode control retained,and chattering phenomenon of sliding mode control has not produced.The controller is designed by combining PID control and synergetic control.Simulation analysis shows that the proposed control algorithm can meet the requirements and maintain the stable operation of the system.