Energy-based Robust Control Of Power Systems With SVC And Nonlinear Loads

The security and stability of the power systems is very important in the people's lives and national economy. Due to its low cost and good reliability, static var compensator (SVC) has been widely used to improve the stability and power quality of power systems. The dynamic model of power systems with SVC and nonlinear loads is a typical complex nonlinear system. How to effectively improve the stability of power systems with SVC by the means of advanced control method is a major issue in the control theory and engineering community. Generalized Hamiltonian system method regards the nonlinear systems in an energy-based point of view. The inherent structural properties of the system can be effectively utilized during the controller design. Furthermore, the controller designed by this method is generally simple in form and has a clear physical significance. This thesis will investigate the robust control of power systems with SVC and nonlinear loads via the Hamiltonian function method. The main contributions of the thesis can be summarized as follows:First, according to the generalized energy balance property of the nonlinear differential algebraic systems, a sufficient condition is given to complete the constant dissipative Hamiltonian realization, which also suggests a process to complete the Hamiltonian realization of the systems. The stability of Hamiltonian realizable nonlinear differential algebraic systems is analyzed and a robust controller is constructed based on the Hamiltonian realization structure.Second, an uncertain nonlinear differential algebraic system model is established for the power systems with (FC+TCR) SVC, nonlinear loads and external disturbances. With the assistant of pre-feedback control, the dissipative Hamiltonian realization of the power system is got. A nonlinear robust controller of SVC is put forward.Third, the coordinated robust control of SVC and generator is discussed. A nonlinear differential algebraic system model is put forward for the system. By completing its dissipative Hamiltonian realization, a decentralized coordinated robust controller is proposed.Finally, in order to show the effectiveness of the proposed controllers, the model of the power systems with SVC, nonlinear loads and external disturbances is constructed based on the Matlab/Simulink simulation platform. Simulation results show that compared to the conventional PID controller, the proposed controllers can not only effectively improve the transient angle stability and voltage stability, but also reduce the impact of external disturbances.