TCSC Controller Design Based On Sum Of Squares Methods

Over the past few years,with the rapid development of China'economy,demand for energy in various industries is growing.As an important secondary energy source,the quality of electric energy is related to the lifeline of the country's industry to a certain extent.At the same time,due to the increasing installed capacity of power generation in China,the safety and stable operation of power system has gradually become a significant research topic.Thyristor Controlled Series Compensation Device(TCSC)is a flexible AC transmission(FACT)device with the advantages of simple operation,fast response and strong adjustability,which also is more flexible and effective than the traditional circuit breakers,simultaneously,its combination with advanced control theory can enrich the control means,thus,TCSC is one of the most effective and economical technical means to improve the stability of power stability.In this paper,several optimal TCSC controllers are designed for a single-machine-infinite-bus power system with TCSC devices under uncertain disturbance and parameter uncertainty by using the sum of squares method.The main contributions of this paper are as follows:In chapter one,firstly,the stability concept,research significance and classification of power system are introduced.Secondly,three main control objects of power system are summarized,and the application status of nonlinear control theory in TCSC devices is discussed.Finally,the research status of sum of squares method is introduced.In chapter two,the synchronous generator and TCSC device are modeled at first,and then the single-machine-infinite-bus power system with TCSC device is established.In chapter three,firstly,the definition and related theorems of Lyapunov stability are elaborated.Secondly,some basic concepts and principles which are related to the sum of squares method are presented,such as polynomial nonlinear systems,convex optimization,semi-definite programming,etc.Finally,the software SOSTOOLS which uses the sum of squares method for computer processing is introduced.In chapter four,considering the single-machine system model with TCSC device,it is difficult to accurately measure the damping coefficient of the generator,thus introduce uncertain parameters,to design a robust controller for the parameter uncertain system.Firstly,the Rantzer asymptotic criterion is introduced,then the polynomial non-negative verification theorem is given.Finally,the method of designing robust controller for polynomial systems with uncertain parameters is given and the simulation is carried out to verify the effectiveness of the designed controller.In chapter five,considering disturbance for the single-machine-infinite-power system with TCSC,the H_?optimal controller is designed by the square sum method.Firstly,the mathematical model of the TCSC-containing stand-alone system is transformed into a polynomial term by the second-order Taylor expansion of Taylor principle,then the sum of squares method is combined with the strategy iteration by loosening the HJI equation to the optimal problem of inequality constraints.The H_?optimal controller was designed and finally simulated to verify the effectiveness of the designed controller.In chapter six,the work of the full text is summarized and and a discussion of the problems which need to be solved if the sum of square mothod should be used reliably in the application of power system is presented.