The inventive method assesses the stability of an
electric power transmission network, where said network comprises a plurality of substations, buses and lines, and a
system protection center (8). It comprises the steps of 1. measuring
phasor data (9) for voltages and currents at a plurality of locations of the network, 2. transmitting said
phasor data (9) to said
system protection center (8), 3. transmitting information (5) regarding the state of switches of at least one substation to the
system protection center (8), and 4. the
system protection center (8) determining at least one
stability margin value of the
transmission network. In this way, detailed real-
time information about the state of the network is collected at a
system level of the network, allowing a corresponding global analysis of the information. In a preferred embodiment of the invention, the
system protection center determines one or more control commands (6), based on the
phasor data (9) and on the state of switches. The control commands (5) are transmitted to at least one substation and executed there.