Filtering And Distributed Networked Control For A Class Of Power System

The performance of the system has been greatly improved after introducing Network as a communication medium in traditional control system.Remote data exchanging has become more easily,and the cost is reduced in a certain extent.However,some problems have been brought in the transmission of information inevitably,such as network delay,packet loss,single packet and multiple packet transmission,and all of these problems will have adverse effects on the performance of the system.Time delay is widely existed in the power system,which has a significant effect on the operation and controlling of the system under a certain condition.Some research shows that even a very small delay may lead the power system to shock.Therefore,we must pay great attention to the delay and deal with it properly to reduce the negative influence,especially in the case of wide area measurement and control.However,few people consider the network delay in the existing research on the controller design of power system,and the design of distributed controllers for wide area power systems is also rarely studied.In this paper,we introduce network into a class of power systems,then a distributed closed-loop networked control system with time-varying delay is obtained,and the problem of?H control and filtering will be studied.By considering the characteristics of network medium,in the first part,a distributed controller is designed for the system.In the second part,we study the filtering problem of the system under external disturbance,which will have an adverse influence on data accuracy and the stability of the system,and a filter for the system is proposed too.Finally,a simulation experiment about a 2-bus 4-power system is proposed to verify the effectiveness of our proposed methods.The work of this thesis is organized as follows:In the first chapter,we introduce the characteristics,advantages and current research status of the networked control system and the main content of thispaper.In the second chapter,we consider the?H control problem of a class of power systems,including the modeling and analysis of the system.We study the stability problem for a class of traditional power system in the network environment,and according to the characteristics of the power system,a distributed controller is designed for the system.Then by the input delay approach,we model the system as a closed-loop networked control system with time-varying delay.Then,the asymptotic stability condition of the system and the delay dependent criterion of the controller are given by Lyapunov theory followed.Finally,a simulation example is given to verify the effectiveness of the proposed scheme.In the third chapter,we study the filtering problem of a class of power system with time delays.We construct a filtering error system with time-varying delay by considering the influence of network induced delay.The delay dependent criterion for the asymptotic stability of the system and the parameters of the filter are given by LMI method,where the Lyapunov-Krasovskii functionals are used.Finally,the validity of the proposed filter is also verified by a MATLAB simulation experiment.In the fourth chapter,we summarize the present research work,including the main contents of this paper and the existing problems.Meanwhile,a prediction concerned about future work is presented.