The Research Of Application Of ANN Controller In MTDC System

High Voltage Direct Current Transmission (HVDC) systems are a typical nonlinear and time-varying plant control systems that poses difficult control problems and complicated control strategies. PID controllers are traditionally used in HVDC system. Although these controllers are no doubt robust and operating satisfactorily since many years, they are prone to changes in system-parameters, delays or other non-linearity in the system, and sufer some limitations.With the development of control theory and technique, intelligent control technology is gradually showing its superiority. It is mainly used for the difficult control problems, which can't be solved by traditional ways. It's high time to introduce intelligent techniques into the HVDC control filed.The HVDC control problems and the background of this thesis are summarized in the first chapter, as well as the AI technique characteristics. Then the theory of HVDC transmission control and its mathematic model are presented.And the main transmission and control modes are compared. The conception of VSF is put forward, according to which three HVDC control modes are further discussed. After that, the optimal control mode of both rectifier and inverter are selected. Finally presents a controller for the fast and flexible control of HVDC transmission on the base of ANN theory. Compared with the traditional PID controller, this controller has more robust stability and this controller response more quickly and has self-study ability. Simulation results show that the controller can improve the stability of Multi-terminal HVDC (MTDC) system.