Coordinated Excitation And Steam Valve Control For Power System Based On Backstepping Method

Power system is a multi-dimensional and strongly coupled non-linear system consisting of power generation,power substation,power transmission,power distribution,power consumption and so on.With the rapid development of power industry,the structure of power system is becoming increasingly complex,and the capacity of power system is increasing.This puts forward more stringent requirements for the stability and reliability of power system operation.Therefore,it is very important to design advanced control system to ensure the stability and reliability of power system.In recent years,the development of some control theories has provided advanced control technology for the field of power system,especially for the stability and robustness of power system and the improvement of transient performance of power system.Under this background,this paper puts forward the corresponding control strategy in view of the various situations that may affect the stability of power system.Through the coordinated control of excitation control system and valve opening control system,the stability of power system is guaranteed.The main work of this paper is summarized as follows:Firstly,according to the components of power system,a fourth-order non-linear mathematical model of power system with excitation control system and steam valve control system is established.Combining the fixed-time theory and Lyapunov stability theory,the backstepping method was used to design fixed-time coordinated controllers.Fixed-time theory is introduced in the design process of the controllers,so that the maximum convergence time of the controlled system is not affected by the initial state of the system after failure,which accelerates the convergence speed of the system and guarantees the transient stability of the system after failure.Then,considering that there are some bounded time-varying external disturbances in the operation of power system,a power system model considering the electromagnetic interference of excitation windings and electromechanical interference of high pressure cylinder is established on the basis of the established fourth-order power system model.Based on the fixed-time theory and Lyapunov stability theory,a fixed-time robust backstepping coordinated controllers are designed by using backstepping method to ensure the stability of power systems with bounded time-varying external disturbances.In addition,considering that the power system often had uncertain parameters besides external disturbances during operation,arobust adaptive backstepping coordinated controllers is designed to give the system adaptive ability for uncertain parameters,and the effectiveness of the proposed control strategy is verified through numerical simulation.Finally,in order to solve the external disturbance problem with unknown boundary and uncertain parameters in power system,this paper combines H-infinity control theory,adaptive control theory and backstepping method.For the power system model with unknown external disturbances and uncertain parameters,this paper designs a robust H-infinity adaptive backstepping coordinated controllers.The robustness of the controlled power system to unknown external disturbances and the adaptive ability of uncertain parameters under the action of the robust H-infinity adaptive backstepping coordinated controllers are verified through numerical simulation.