Nowadays, PMU (Phasor Measurement Units) technologies, as part of Smart Grids, have taken an important attention due to its ability to perform synchronous measurements in real time. With PMUs, it is now possible to measure online voltage angles at busbars of the Electrical Power Systems. From bus angles and other variables, new methodologies are being developed to quickly generate alarms; which may or may not activate controls for the system security. One of these indices is known as cutset angle, which involves in its calculation line susceptances, angular differences between busbars and power flow measurements. In this paper, the stress condition and strength of a power system is evaluated under novel indices and a methodology proposed from angles synchronized measurements. Global protection schemes founded on PMU measurements are also proposed.