Research On Power System Stability Control Based On Switching Theory

The power system is a large-scale nonlinear system,which contains various subsystems,and there is a complex dynamic relationship between the subsystems.A switching system is a system that consists of a limited number of continuous(or discrete)subsystems and switches according to a certain switching rule.Since this system can model multi-modal or multi-controller systems,the switching system can be introduced into the study of power system stability.The basic idea is that when the power system fails or is subject to large external interference,the design of the controller and switching law enables the power system to smoothly transition to a new equilibrium state,thereby improving and improving the power supply safety and quality of the power system.In this thesis,a three-machine power system model for switching will be established,and the switching model will be divided into 7 subsystems according to the actual situation of synchronous generator failure and maintenance.First,the controller is designed for each subsystem based on the backstepping method and the Lyapunov method,and secondly,the multi-Lyapunov function method is used to design the switching law to ensure that the switching between any two subsystems is stable.The research results include the following parts:First,establish a three-machine power system switching model.According to the actual situation,when the generator is damaged or needs to be repaired and exit the power system,the three-machine power system is divided into 7 different subsystems.Secondly,based on the established three-machine power system model,the backstepping method is used to establish an excitation controller for each subsystem.Then,a multi-Lyapunov function method is used to design the switching law to ensure that the three-machine power system can maintain stability under the effect of the switching law.Finally,through simulation,the effectiveness of the designed controller is verified.Finally,considering the uncertainty of the damping coefficient of the synchronous generator,a switched three-machine power system model with uncertain parameters is established.In order to speed up the convergence of the power angle,a K-type function is introduced.Lyapunov function analyzes the stability during the switching process,and design the switching law to ensure the stability of the switching process.