Nonlinear Roubst Control Of High Voltage Direct Current Transmission System

Modern power systems are attributed to a class of nonlinear, uncertain and decentralized high-order dynamic systems. HVDC @ FACTS provide brand new control resources for power system stability control. The application and development of nonlinear control theory in power system build up solid theoretical base for nonlinear control of HVDC systems. This research subject takes great advantages of high controllability of HVDC and summarizes the newest research achievements of power system nonlinear control and places great emphasis upon the design of advanced controller with high robustness and adaptability based on inherent features and fundamental requirements on stability control of power systems. The main research contents are briefly concluded as follows:Firstly, the configuration, benchmark circuit model and mathematical model of HVDC are introduced concisely as well as the simulation software generally used in AC/DC power systems by domestic and abroad researchers. The principles and methods of simulation modeling for AC/DC power system are proposed based on specific requirements of HVDC auxiliary control research concerned with the simulation tools mentioned above.Secondly, a novel extended state observer based nonlinear robust control method (ENRC) is proposed. According to the symmetrical study on power system plants, a class of nonlinear MIMO plants composed of nonlinear internal-loop system and pseudo-linear external-loop system is generalized. On the basis of this mathematical model, the main methodology of ENRC is explicated that by using the extended state observer, the dynamic feedback linearization of nonlinear internal-loop system can be implemented; by employing the Linear Robust Control Theory, the anticipating dynamic characteristic design of the linearized internal-loop system and pseudo-linear external-loop system can be fulfilled. The core idea of ENRC is to pursue the perfect combination of state observer, feedback linearization and robust control, and so to solve a class of controller design problems of nonlinearity, uncertainty and decentralization. The close-loop stability of ENRC is analyzed by means of constructing Lyapunov function.Thirdly, the ENRC method is applied to nonlinear robust control of HVDC basic valve control systems. The constant current control rule on rectifier side and constant extinction angle control rule on inverter side are proposed based on EFL and ENRC. The simulation results show that if the plant model is certain the control performance of ENRCC is similar to the exact feedback linearization methods; and on the other hand, if the plant model is uncertain, the robustness and the adaptability of ENRCC is obviously stronger than the latter. Furthermore, the research on dynamic stabilities of HVDC and its control systems are...