EEI SOPD Practice Test 14

How a Utility Plans for a Cold Snap

¹A cold snap is a period of several days when temperatures fall well below normal. For an electric utility, it brings two problems at once. Customers use more electricity for heating, so demand climbs, and the same cold that raises demand can freeze equipment at power plants. Because severe cold can arrive with little warning, utilities prepare long before the first winter storm.

²Planning begins in the fall. Generating plants check their heat tracing, which is electric heating cable wrapped around water lines and instruments so they do not freeze. Crews put up temporary wind breaks and enclosures around exposed equipment. Plants that can burn more than one fuel test their backup fuel systems and fill their storage tanks, because natural gas for power plants may be scarce when homes and businesses also need it for heating.

³When forecasters predict a cold snap, the control center takes further steps. Planned maintenance that would remove a generator or a major line from service is postponed, so that as much equipment as possible is available. Extra operators and field crews are scheduled. Planners study the forecast to estimate the highest demand, which in winter usually comes on cold mornings, when people wake and turn up the heat, and again in the early evening.

⁴If demand still threatens to exceed supply, the utility works through a series of actions, starting with the least disruptive. It may buy power from neighboring systems, ask customers to conserve by lowering thermostats and delaying the use of large appliances, and reduce voltage slightly within allowed limits. Only as a last resort does it interrupt service to groups of customers for short periods, rotating the outages so that no area is without power for too long.

⁵After the cold snap ends, staff review what worked and what failed. Equipment that froze is studied so that it can be better protected before the next winter.