Power System Conditions – ISO

What happens when Power Shortages are predicted!

There are many steps the Independent Systems Operator of New England (ISO) orders electric utilities in New England to take in order to “stretch” electric power supplies. Most of these are indiscernible to electric customers, such as dispatching all generators and reducing voltage. Others involve customers, such as requests for conservation. When shortages are predicted, the Hudson Light and Power Department prepares its customers for what to expect.

The quarterly Customer Newsline is used to advise all customers of what might happen during a power shortage. Notices are sent to Medical Emergency Customers to ensure that the Department’s information on these special accounts is as up to date as possible. Larger industries are contacted to participate in the Voluntary Load Curtailment program involving fax and or telephone notification of power supply conditions in return for voluntary electric use reduction upon request. The local media is supplied with the various terms New England’s utilities use if the power supply situation becomes seriously tight.

Prime periods for emergency situations are weekdays, between noon and 8 p.m., during periods of extended heat waves and unhealthy air quality. Historically, this weather usually occurs in July and August. Following are some of the terms electric customers may hear broadcast by the media, or see flashed on the Department’s Web Page, during emergency situations. These terms are not unique to the Hudson Light and Power Department, but would be used across the region. For more information on New England’s power status, see www.iso-ne.com/index.html.


Terms

Normal – Conditions are considered normal when electricity supply is sufficient to meet expected demand plus required operating reserves.

Power Caution This is an advisory to utilities that available capacity resources are insufficient to meet anticipated demand plus operating reserve requirements. This is not a request for electricity conservation.

Power Watch –  This is a public advisory that high demand for electricity in the region has created the need to conserve electricity. Voluntary electricity conservation by the public is requested. The public can conserve electricity at home and at work by turning off unnecessary lights, equipment, and appliances, and minimizing the use of air conditioning. People who require air conditioning and other electrical appliances for health and safety reasons should not restrict their use.

Power Warning – This is a public notification that immediate reduction in power usage is needed to help protect the region’s electricity system. The public is urged to reduce electricity use immediately. The public can conserve electricity at home and at work by turning off unnecessary lights, equipment, and appliances, and minimizing the use of air conditioning. People who require air conditioning and other electrical appliances for health and safety reasons should not restrict their use.

One of the steps utilities may be ordered to take during a Power Watch is a Voltage Reduction. ISO may order utilities to reduce voltage on their systems by five percent. Indiscernible to the average customer, voltage reductions have occurred in the past. Customers concerned about sensitive appliances should check with instruction pamphlets or with their suppliers. It is recommended that customers check sensitive electronic equipment and back up computer data more frequently.

When the demand for electricity becomes extremely high and there are insufficient supplies to meet the demand, ISO may order a Voluntary Load Curtailments. Utilities are told to ask their larger businesses to voluntarily reduce their electric consumption. Hudson Light partners with large industrial customers on voluntary load curtailment to help avert the need for more stringent measures.

Power Interruption Alert: When utilities have enough advanced notice that rolling blackouts are required, a “Power Interruption Alert” will be issued to notify electric customers that interruption of electric service is imminent. Rolling Blackouts are one of the rare and final steps taken to avoid collapse of an electric system. One has never been issued in New England. When ordered to implement Rolling Blackouts, utilities shut down various circuits in a rotating pattern until the crisis eases.

During rolling blackouts, customers should not be without power for more than a few hours at a time. When service is interrupted, major appliances should be turned off to avoid damage when service is restored. This is especially important for industrial equipment. If such equipment is left on, the surge to restart the machinery when power is restored could trip circuit breakers and delay the orderly restoration of power to the area.

It is important to note that utilities may not have advanced notice of a Rolling Blackout or Voltage Reduction. The Department’s Web Page will be used as one means of notification. While voltage reductions have occurred in the past, Rolling Blackouts have never been ordered by ISO. As a result, utilities are trying to prepare now for any eventuality this Summer. Hudson Light and Power Department Customers with questions or concerns should feel free to call the Hudson Light and Power Department at 978-568-8736. Customers of other utilities should contact their own electric companies.