Design of a Nonlinear Global Integrated Controller Based on Wide-area Information

With the wide application of synchronized phase measurement unit (PMU) in power system, the wide-area measurement system (WAMS) has enabled the use of a combination of measured signals from remote location for global control purpose. Since in nature power system stability is related to all generators, the introduction of wide-area information into nonlinear integrated control can improve the dynamic performance of power system and enhance power system stability. According to multivariable inverse system theory, this paper verifies the invertibility of excitation and turbine control system for a turbogenerator under the center of inertia reference frame (COI), and presents a novel nonlinear global integrated controller based on wide-area information including the on-line measured center of rotor angle and total unbalanced power. This controller makes the relative rotor angle to the center of angle return to its pre-disturbance value by modulating excitation voltage and turbine valve, and is considered as a "control the local to serve the global" controller. Digital simulation demonstrates that the four-machine power system under the nonlinear global integrated control has less settling time, swing times, oscillatory peak value and more critical clear time and better transient stability performance than that under PID control and nonlinear decentralized integrated control.