Sub second control actions required in the 10- or 100-ms cycles are made possible by the advent of synchronized measurements and FACTS-based fast repetitive control actions. The measurements are validated using various filtering/regression approaches (10- or 100-ms “state estimation” agent) at the lowest level possible (equipment level, bay level, etc.). The calculations are fundamentally different from the conventional state estimation because only about half a power frequency cycle is available for observation. The estimated data may include the amplitude, frequency, and phase angle associated with the instantaneous values of individual phase currents and voltages. Estimating the rates of changes of these parameters may also be critical. Non conventional data errors may arise from phase imbalances, saturation, and noise from a variety of other control actions throughout the system (e.g., switching transients). Communication delays are a significant part of the total response time. The location of each agent in these cycles is assigned to minimize the delays (assuming one-way delays of about 0.2 ms within a substation and 6 ms between substations). See [21] and [22] for further details of the tasks in various cycles and hierarchical levels.