from PMUs installed at the most representative European electrical transmission nodes. The gray boxes on the map show the angle difference (degrees) between the different locations; the absolute value is a measure of the equivalent active power flowing through the system, and the sign shows the direction. It is a clear picture of the real behavior of the system. In addition, it reports the synchronized value of the frequency, which is very useful in discovering possible large network splitting scenarios and in controlling system frequency and deviations. In conclusion, a modal analysis algorithm processes the angle difference over the north-south and east-west measurands, generating an alarm if the damping ratio decreases below critical values. 242 241 Restoration Path from Switzerland "Italia 2" Four Maneuvers 4 X 201-Mvar Shunt Reactors 1,001 km figure 6. A restoration test path from Swiss Network. 10:25 a.m.: Circuit Breaker Lacchiarella-Chignolo Line Closed 10:27 a.m.: Circuit Breaker Martignone-Bargi Line Closed 240 10:47 a.m.: Outage of Presenzano Group 239 238 237 10:57-10:59 a.m.: Remeshing Actions 236 235 234 233 232 10:41 a.m.: Synchronization of Presenzano Group End of the Test 231 230 229 228 10:31-10:32 a.m.: Variation of Tap Changer Lavorgo Transformer 227 226 225 224 10:34 a.m.: Circuit Breaker Suvereto- Montalto Line Closed 10:22 a.m.: Circuit Breaker Musignano-Lavorgo Line Closed Staring Point of the Test Phase-to-Ground Voltage 10:51 a.m.: Circuit Breaker Suvereto- Montalto Line Opened Phase-to-Ground Voltage Phase-to-Ground Voltage figure 7. Phase-to-ground voltages in Musignano. september/october 2015 ieee power & energy magazine 45