Study On The Backstepping Adaptive Variable Structure Control For The Nonlinear Power System

Energy is one of the country's economic lifeline, to study the stability of the power system is very important. Now advanced control theories and methods are applied to the direction research of the electric power system, such as the optimal control, variable structure control, robust and intelligent control and so on.Power system is a very complex nonlinear system, sometimes only one kind of control method will not solve the problem, therefore several control methods need to be combined with each other and comprehensive control to achieve the desired results. In this paper variable structure control, adaptive control and backstepping method are combined with each other, then backstepping adaptive variable structure control method which is applicable for any order for a class of nonlinear systems is proposed and is applied to power system stability control. Power system control effects are discussed and the research work is as the following:(1) For one class of n-order nonlinear systems, the design principles and specific processes of the backstepping adaptive variable structure controller is described and the stability, robustness is proved. A controller of a high order nonlinear systems is designd, and the numerical simulation shows the effectiveness of the controller.(2) With uncertain parameters for a large generator valve control system model, backstepping adaptive variable structure controller of a large generator with Steam valve is designed. Simulation results show that the controller not only can improve the static and transient stability, but the effect of its control is better than backstepping adaptive controller.(3) The backstepping adaptive variable structure control is extended to MIMO power systems, the mathematical model of the single-machine infinite system with SVC and excitation system is established, considering the uncertainty of damping coefficient, backstepping adaptive variable structure control method is used to design the coordinated controller. The controller not only meet system power angle and the voltage stability of SVC access points but the control effects is better than backstepping adaptive controller.(4) The backstepping adaptive sliding mode control is applied to the multi-machine power systems and uncertain parameters of multi-machine power system model is established, then the backstepping adaptive variable structure excitation controller is designed and the control device implementation is discussed. Four-machine two-area system simulation results indicate that the controller can make multi-machine system transient stable, and stability better than the PSS control.