Coordinated Control For Steam Turbine Generator Excitation And Steam Valve

Power system is a kind of complex nonlinear, dynamic system. In recent years, with the improvement of people’s production and living standards, as well as the rapid development of power industry, the big leap in single unit capacity, the power network structure has witnessed a rapid increase in the complexity, these is not conducive to the stable operation of the power system. Previously, the frequency of blackout makes the countries all over the world are quite seriously on power system stability problems. Power system mainly consists of four links:motivity, power generation, electric power transmission and power distribution. Including the four links, motivity and power generation play the leading role in the whole power system, the control effect of them directly affects the transient and the static characteristics of the whole power system.So, the steam value control and the generator excitation control are the main control problems for the steam turbine generator. In this dissertation, with the comprehensive consideration of the control problems, based on the back-stepping method, coordinated control for steam turbine generator excitation and steam valve is studied. The main contributions are as follows:In chapter one, firstly a brief review of coordinated control problem for excitation and steam valve is given. Then the nonlinear control methods and their recent applications in this problem are introduced respectively. Finally the main work of this dissertation is summed up.In chapter two, the differential mathematical model of coordinated control system with steam turbine generator excitation and steam valve is built. The model considers problems simultaneously as follows:the multiple uncertain parameters and external disturbances, the full range control of the main steam valve and the fast steam valve, the steam valve control input constrains.In chapter three, based on the back-stepping method, aiming at the nonlinear system with the multiple uncertain parameters and external disturbances, combined with the switched control thought, the robust control method is developed. Then the method is applied to the differential mathematical model of coordinated control system with steam turbine generator excitation and steam valve. Finally the influence of design parameters on control effect is studied through simulation, the design proposal is proved to be valid through theoretical analysis and simulation results.In chapter four, aiming at a kind of nonlinear system with the multiple uncertain parameters and external disturbances, the coordinated passivation method is studied, and then it is applied to the differential mathematical model of coordinated control system with steam turbine generator excitation and steam valve. The influence of design parameters on control effect is studied through simulation, the design proposal is proved to be valid through theoretical analysis and simulation results. Finally the advantage of the coordinated passivation controller in practical application is analyzed.Concluding remarks and some open problems for further study are presented at the end of this dissertation.