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Robust Analysis And Disturbance Rejection Design For Load Frequency Control System

Posted on:2018-03-18Degree:DoctorType:Dissertation
Country:ChinaCandidate:H ZhouFull Text:PDF
GTID:1312330518955396Subject:Control theory and control engineering
Abstract/Summary:PDF Full Text Request
Load frequency control(LFC)is an important measure to maintain the frequency stability of power systems.With the development of the power market after the deregulation,the robustness and disturbance rejection performance of LFC sy stems becomes more and more critical.This dissertation proposes a method to analyze the stability and robustness of the power system under decentralized LFC control considering the special structure of LFC systems,and proposes to adopt active disturbance rejection control(ADRC)method to improve the disturbance rejection performance of LFC systems.Main contents of the dissertation includes:1.A method to analyze the power system under the decentralized LFC control is proposed considering the special structure of LFC systems,and separate the robustness analysis of the closed-loop system into two parts: robustness against parametric variations of local area and robustness against tine-line power flow network.This method reduces the complexity of robustnes s analysis for the entire power system.It can reveal the effect of tie-line network on the stability of the power system,and is useful in the construction of power system network.2.To improve the disturbance rejection performance,ADRC is adopted in LFC design by utilizing the on-line disturbance estimation performance.The structure and parameters of ADRC for LFC systems are analyzed and parameter tuning methods are proposed for power systems with different turbines.To overcome the generation rate constraints(GRC)of the turbines,an anti-windup scheme is proposed for ADRC to compensate GRC.Simulation results show that ADRC is easy to tune for LFC and is superior to conventional PID controllers in disturbance rejection,thus has potential application in LFC.3.The structure of LFC systems in power market is analyzed.It is shown that under deregulated environment the contracted loads amount to adding multiple disturbances in LFC system under conventional environment,thus LFC system in power market should have stronger disturbance rejection performance than under conventional environment.The stability of the power system under power market is also analyzed for decentralized LFC control.It shows that the contracted loads will not affect the stability of the power system under conventional environment,thus decentralized control design under conventional environment can still be applied in power market,and ADRC is an efficient control method for LFC design in power market.
Keywords/Search Tags:load frequency control, robustness analysis, active disturbance rejection control, structured singular value, power market
PDF Full Text Request
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