Electricity Markets

Report sees adequate Eastern Interconnection frequency response

Despite a changing resource mix, the Eastern Interconnection, which covers about two-thirds of North America, has the ability to maintain system frequency for at least the next five years, according to a report from the Eastern Interconnection Planning Collaborative.

The Eastern Interconnection’s projected resource portfolio will support frequency response, the ability of the grid to bounce back after disturbances, the EIPC said in the report released April 4. The grid’s frequency varies as supply and demand changes from moment to moment.

The inability to respond to drops in frequency can lead to power outages.

Synchronous generators, such as oil- and coal-fired and nuclear power plants, respond automatically to drops in frequency by slowing down slightly and releasing more energy into the grid, the EIPC explained.

In contrast, the asynchronous wind and solar generators are less responsive to frequency changes, unless they have been equipped to provide some form of frequency control.

“As the generation resource mix continues to evolve over time to incorporate new and emerging technologies and address energy and environmental policies, it is essential to understand how the Eastern Interconnection will be poised to maintain system frequency under a wide range of operating conditions,” said Stephen Rourke, vice president of system planning for ISO New England and chair of the EIPC Executive Committee.

The EIPC task force that wrote the report studied three hypothetical events for 2022, including the loss of 4,500 megawatts, the Eastern interconnection’s most significant frequency event in the last decade, and a 10,000 MW event.

“The system inertia and primary frequency response will be sufficient even with expected retirements of synchronous generation and increases in non-synchronous generation,” the report said.

The report established a framework and baseline for system planners to improve system network models, provide enough notice when the changing resource mix could hurt frequency response and develop solutions if needed, said Steven Judd, lead engineer in system planning for ISO-NE and chair of the EIPC Frequency Response Task Force.

The EIPC, made up of 20 transmission planning coordinators, conducted the frequency response analysis for the NERC Essential Reliability Services Working Group. Members of the group include public power entities JEA, the Municipal Electric Authority of Georgia and Santee Cooper.

EIPC plans to periodically update its frequency response analysis.

In early 2018, the Federal Energy Regulatory Commission approved a rule that requires all new generating facilities be able to provide frequency response.

Among other things, the final rule requires minimum operating conditions to help ensure frequency response capability will be available. Existing power plants will face the new frequency response requirements if they decide to make upgrades that necessitate a new interconnection request.

The report is available here.