Design of wide-area damping control systems for power system low-frequency inter-area oscillations

The recently developed robust control theories and wide-area measurement technologies make the wide-area real-time feedback control potentially promising. The objective of this research is to develop a systematic procedure of designing a centralized damping control system for power grid inter-area oscillations by applying wide-area measurement and robust control techniques while putting emphasis on several practical considerations.; The first consideration is the selection of stabilizing signals. Geometric measures of controllability/observability are used to select the most effective stabilizing signals and control sites. Line power flows and currents are found to be the most effective input signals. The second consideration is the effects of time-delay in the communication of input/output signals. Time-delays reduce the efficiency of the damping control system. In some cases, large delays can destabilize the system. Time-delays should be modeled in the controller design procedure so that the resulting controller can handle a range of time-delays. In this work, time-delays are modeled by Pade Approximations and the delay uncertainty is described by Linear Fractional Transformations (LFT). The third consideration is the controller robustness. The synthesis of the controller is defined as a problem of mixed H2/Hinfinity output-feedback control with regional pole placement and is resolved by the Linear Matrix Inequality (LMI) approach. The controller designed by robust control techniques has satisfactory performance in a wide range of operating points. The fourth consideration is the efficiency of the controller designed by linear techniques in realistic nonlinear discrete environments. A tuning process and nonlinear simulations are used to modify the controller parameters to ensure the performance and robustness of the controller designed with linear techniques. The last consideration is the selection of PMU data reporting rates. The performance of controllers designed in the s -domain is tested in digital environments and proper PMU data reporting rates are selected with consideration of the effects of time-delay.; The design procedure of wide-area damping systems is illustrated by three study systems. The first study system is a two-area four-machine system. The second one is the New England 39-bus 10-machine system. The last one is a 29-generator 179-bus study system, which is a reduced order model of the Western Electricity Coordinating Council (WECC) system.; Keywords. Damping controller, data reporting rate, Hinfinity synthesis, LMI, PMU, inter-area oscillations, robust control, time-delay, wide-area.