ISO New England is required under a North American Electric Reliability Corporation (NERC) reliability standard to maintain operating reserves—power system resources capable of activating quickly to make up for a sudden loss of the region’s largest electricity source.
Reserves may be dispatched anytime a resource goes off line unexpectedly, or when consumer demand is higher than expected. If there are no other resources available to take over as reserves, the region may experience a reserve shortage.
A reserve shortage does not necessarily indicate an immediate threat of consumers losing electricity, though supply is tighter than normal. To ensure the region’s reserves are replenished and power keeps flowing, ISO-NE system operators take additional steps described in Operating Procedure No. 4: Action during a Capacity Deficiency, also known as OP 4. Options include requesting emergency imports from neighboring regions, initiating voltage reductions, or, if needed, requesting public conservation.
This procedure also includes three notification levels designed to keep industry personnel and the public informed of power system conditions.
A Power Caution indicates that a capacity deficiency exists.
What we’re doing: At this stage, ISO-NE system operators are using OP 4 actions to manage operating reserve.
What the public can do: No action required.
A Power Watch indicates a capacity deficiency exists and further actions of OP 4 may be required to maintain reserves.
What we’re doing: ISO-NE operators may utilize additional OP 4 actions to maintain reserves. The ISO also may request voluntary conservation from the public.
What the public can do: If a request for voluntary conservation is made, you can help out at home or at work by turning off unnecessary lights, equipment, and appliances. In the summertime, you can stop or limit the use of air conditioning. In the wintertime, you can turn down the heat.
A Power Warning indicates an urgent need for a reduction in power usage.
What we’re doing: Our system operators are utilizing various OP 4 actions to balance supply and demand. We’re also issuing an urgent request for the public to reduce electricity use immediately.
What the public can do: You can conserve electricity at home and at work by turning off unnecessary lights, equipment, and appliances, and minimizing the use of heating or air conditioning. People who require heating, air conditioning, or other electrical appliances for health and safety reasons should not restrict their use.
