A single-machine-equivalent (SIME) based emergency control (EC) scheme that incorporates synchronized measurements is described in the paper. This EC scheme resolves the transient stability problems experienced when serious disturbance occurs on critical transmission lines. The control actions are based on modifying the impedance of a thyristor controlled series compensator (TCSC). The SIME approach is first used to evaluate the transient stability of the system and then a decision is made about the control actions needed to stabilize the system. During emergency conditions, a fast response time is very important and this requires a security guideline to be used in the decision making process. The guideline is developed by analyzing offline multiple fault scenarios using a supervised learning approach. This ensures appropriate control actions can be performed without compromising the response time required on a real system. Finally, the emergency control (EC) scheme is tested and verified using an idealized four machine system. (5 pages)