This use case describes how the coordinated use of phasor measurement data and FACTS devices could enable SCE to maintain system stability following a destabilizing event such as the loss of a transmission line or substation transformer. SCE currently uses phasor data to evaluate system conditions on a post-mortem basis, following such events. This use case describes the use of phasor data to control FACTS devices to restore system stability within 10 seconds of an event. This capability would reduce the likelihood of an event causing widespread catastrophic grid instability. Phasor data measures the physical characteristics of voltage and current waveforms, including phase angle and frequency oscillation. If frequency oscillation is identified, SCE’s Predictive Grid Control System would calculate an optimal oscillation damping strategy, and send control messages to FACTS devices to execute the damping strategy. This use of phasor data to control FACTS devices represents one method within a portfolio of tools to combat system instability, and should be considered within a broader context of intelligent grid control. Other methods include Centralized Remedial Action Schemes (discussed in use case D15), and tools that optimize for other system variables such as transmission loss, volt/VAR control, generation dispatch, and renewable resource penetration levels. The benefits of this process include improved system reliability, reduced costs and increased customer benefits.