Nonlinear Excitation Controller Research Based On Wide-Areas Measurement System

With the development of large-scale interconnected power system network, it brings prominent economical benefits at the same time, power system is running in limit state because of restricts of environment and economy favors. It makes the stabilization problem of power system increasingly evident. Once system stability is destroyed, it causes the calamity result of system collapse, which gives rise to power cut in long time and large range. To develop control system is the primary means to improve and enhance power system's stability. Excitation controller is regarded as one of the most efficient and economic means, which may improve transient stability and dynamic performance. As to power system suffering all kinds of disturbance occasionally and possibly, it is important to find out suitable excitation control rule to improve system's transient stability.On the other hand, the development and maturation of related techniques, for example computer, network, wide-area measurement system, nonlinear control technique, and so on, provide conditions to improve excitation controller's performance. Since it is produced that Wide-Area Measurement System (WAMS) based on Global Positioning System (GPS) and Phasor Measurement Unit (PMU), generator's angle and bus voltage phase may be monitored really, which may observe the whole system network's true running conditions. So WAMS supply key measure methods for the security and stability operating of power system.This paper tries to make use of the advantages of wide-area measurement system, and adopt a few of nonlinear control methods, and design nonlinear excitation controller and tracking objective excitation controller to meliorate the dynamic performance of power system and increase power system's stability.At first, the paper summarizes the research conditions that overseas research made in excitation control and WAMS, and introduces the nonlinear excitation control theory, and expatiate the applying of WAMS in the stability control of power system, especially nonlinear excitation control.Secondly, aiming at the problem of local measure information not really reflecting the whole system network's running conditions and resulting in mistake control decision-making, the paper takes some real-time whole information into account and introduces WAMS into the nonlinear excitation control model under two different reference frames. A new nonlinearly variable structure excitation control law is come to a conclusion adopted by feedback linearization in the nonlinear system and variable structure control theory in the linear system. Power System Analysis Software Package (PSASP) developed by electric power science academe is used as research tool. The simulation results illustrate that the designed controller has powerful capability of receiving large disturbance and improve the system stability through three-machine and nine-bus module of PSASP.Thirdly, aiming at the inaccurate existing in local linearization theory and the module's complexity existing in precise linearization theory, the paper adopts observational linearization and tracking objective excitation control theory to design a new nonlinear excitation controller. The effectiveness and superiorities of the designed controller is verified through simulation.Finally, the paper summarizes the developments and trends of the nonlinear excitation control and wide-area measurement system.