FERC issued a Notice of Inquiry last week, seeking comment on potential changes to its rules on the provision and compensation of primary frequency response (RM16-6).

“In recent years, the nation’s electric supply portfolio has transformed to a point where fewer resources may now be providing primary frequency response than when the commission considered this issue in other relevant proceedings,” Jomo Richardson, of the Office of Electric Reliability, said in a presentation at the commission’s open meeting.

Primary frequency response is the ability of generators to automatically change their output in five to 15 seconds when the grid’s frequency strays above or below 60 Hz. It, along with slower-responding secondary frequency response and system inertia — the release or absorption of kinetic energy by the rotating masses of online generation and load within — are crucial to reliability.

FERC is concerned that the growing integration of wind and solar resources, and the retirement of coal generators and other synchronous units, “have the potential to reduce system inertia,” making the system more susceptible to frequency changes in response to the loss of generation and reduction of load.

The NOI asks whether the pro forma interconnection agreements should be revised to require that all new generation resources have frequency response capabilities.

It also asks whether the commission should implement frequency response requirements for existing generators, and whether it should establish procurement and compensation mechanisms for the service.

“In my view, the questions posed are thoughtful and set a framework to explore a broad range of possible solutions,” Chairman Norman Bay said.

FERC has previously approved frequency response obligations for balancing authorities and permitted the sale of the service at market-based rates by generators. (See FERC to OK 3rd Party Sales of Frequency Response.)

— Michael Brooks