After A Storm
Utilities are most often affected by outages caused by downed tree limbs, high winds or other acts of Mother Nature. Restoration during these kinds of outages requires the utility to pinpoint the exact location of the damaged area on the grid so that the line or equipment can be taken out-of-service and fixed. Typically, these kinds of outages are contained to smaller areas and many times the utility is able to serve the customer from an alternate source so power is not lost for a long period of time. Restoration by utilities in this sort of event includes rerouting the electricity through a backup feed, or bringing in a mobile generator, substation and/or transformer, until the repairs are made and the equipment is put back into service.
After A Blackout
Restoring power after a widespread blackout (such as what occurred in the East on Aug. 14, 2003) is much different than the process utilities follow to repair damage to the electrical grid caused by a storm or other physical hazard. In a blackout situation, the balance between generation and load is affected, causing the transmission grid to become unstable and collapse and customer load to be lost. Restoring power from a blackstart situation requires the successful initiation of a pre-planned sequence of events beginning with the firing of peaking units and hydro plants, which, in turn, prompt start-up of larger generating units, such as coal, nuclear and gas-fired power plants. This is a skillful and delicate process requiring system control operators to precisely match the amount of power and energy released on the transmission grid with the customer load being restored at the “end of the line.” This process is carefully followed and repeated until all customers have power restored and the grid is stabilized.