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Operating Procedure No. 4
One of these procedures is Operating Procedure No. 4 (OP-4), Actions During a Capacity Deficiency. This procedure is invoked when a deficiency of required operating reserves has occurred or is imminent. The procedure includes 16 steps that the operators can take to either increase the available supply of electricity for the region or reduce the actual real-time demand for electricity. These steps can be implemented in any order depending on the circumstances of the capacity deficiency. In addition, some of the steps can be implemented in advance of an anticipated capacity deficiency situation. The potential load relief resulting from implementing all 16 steps of the procedure is between 4,400 MW and 5,400 MW.
It is important to note that OP-4 is an implicit part of the reliability design of the bulk power system in New England. It was envisioned that there would be instances when required operating reserves could not be maintained and that appropriate contingency measures needed to be in place.
Public Notifications Under OP No. 4
For 10 years, ISO New England has used a public notification system when the OP-4 action requires the ISO to ask customers to conserve electricity. Modeled after advisories used by the National Weather Service, the ISO New England public notification system has two levels of appeals, Power Watch and Power Warning.
A Power Watch is a request to all customers to voluntarily reduce electricity usage and is issued when the region's electricity supplies are expected to be tight.
A Power Warning is a more urgent appeal and is issued when electricity supplies are—or are expected to be—extremely tight and there is concern that electric companies may have to disconnect certain customers as a means of reducing demand on the grid.
A follow-up notification is issued to the public once the Power Watch or Power Warning has been lifted. ISO New England will issue a notice that power supplies and operating reserves have returned to normal levels and that regular electricity usage can resume.
Operating Procedure No. 7
Another operating procedure triggering a public notification and request for conservation is Operating Procedure No. 7, Action During an Emergency. This procedure calls for specific actions to be taken to protect the integrity of the region's bulk power system when a system emergency such as low frequency, unacceptable voltage conditions or a transmission emergency occurs. Steps under OP-7 include disconnecting blocks of customers in a specified area of New England to protect the rest of the bulk power system. Whenever possible, ISO New England will notify the public ahead of time of this event.
Other Operating Procedures
Other ISO New England procedures to protect the integrity of the region's bulk power system do not require public notification or a request for conservation, but may require actions on the part of participants in the wholesale electricity marketplace. These include Master/Local Control Center Procedure No. 2 and Operating Procedure No. 20, Cold Weather Event Operations.
