FERC begins inquiry on frequency response, reliability services from generators

With fewer generation resources providing frequency response capabilities to enable the power grid to withstand disturbances, FERC on Feb. 18 began seeking industry input on whether it should address the issue to ensure that power grid reliability is maintained.

The notice of inquiry (NOI) approved at the Feb. 18 meeting seeks comment on whether FERC should alter generator interconnection requirements, call for existing generation units to provide frequency response services or establish market mechanisms that compensate generators that provide frequency response services.

Frequency response is a measure of the power grid’s ability to stabilize frequency deviations following the sudden loss of generation or load, FERC explained in the NOI. Power grid operators strive to maintain balanced frequency on the grid at about 60 Hz, but they sometimes experience frequency deviations, such as the loss of a large generator, that disrupt the generation and load balance and require actions such as an increase in generation within seconds to avoid under frequency load shedding or cascading outages, FERC said.

Frequency response is most often provided by turbines at power plants that have governors that automatically adjust output based on changes in frequency, and most renewable resources do not have such equipment to quickly adjust output unless they are specifically designed to do so, according to the order (Docket No. RM16-6).

FERC staff noted at the meeting that the inquiry was preceded by a NERC task force report that said the provision of “essential reliability services” such as frequency response and voltage control will become more important for reliability as the generation mix changes. Those changes include the retirement of large baseload units and the addition of more renewable resources, distributed generation and natural gas-fired units due to state policies, environmental regulations, tax incentives and low natural gas prices, FERC staff said.

The FERC proceeding sets a framework for possible solutions to allow the different types of resources to connect with the bulk power system and ensure reliability is not harmed, said FERC Chairman Norman Bay.

Because the generation mix is changing, the issue will become more important in the future and it is good for FERC to seek input and be prepared to address the trend, other commissioners said at the meeting.

FERC has seen the changes happening, including the influx of demand response and storage resources, and it is wise to contemplate if any policy changes are needed, said Commissioner Colette Honorable.

“NERC appreciates FERC’s actions on frequency response as a positive step toward ensuring the future reliability of the bulk power system,” a NERC spokesperson told TransmissionHub Feb. 18 following the FERC meeting.

NERC concluded in 2015 that the ongoing transformation of the resource mix “requires a greater focus on the ability of new resources to provide adequate levels of essential reliability services,” including frequency response, to maintain reliability, the NERC spokesperson said, referring to the report and a series of videos on frequency response, load ramping and voltage control.

NERC and others have indicated that variable energy resources such as wind and solar power facilities have made significant advancements in recent years to develop the necessary controls that would enable them to provide frequency response, FERC said in the order.

A U.S. Department of Energy laboratory in late January issued a report on how solar power facilities can be designed to be more grid-friendly through enhanced controls to rapidly adjust their output if needed.

As TransmissionHub reported, frequency response is the subject of a separate but similar proposal from the California ISO (Cal-ISO), which reported that it has seen frequency response performance diminish with the increase in renewable resources in the state.

As did the Cal-ISO in its proposal, which has yet to be addressed by the Cal-ISO board, FERC noted that NERC’s frequency response grid reliability standard (BAL-003-1) calls for compliance to begin Dec. 1, with grid operators demonstrating sufficient frequency response capabilities stemming from disturbances or a loss of generation contingency.

In the NOI, FERC sought comments on whether the pro forma large generator and small generator interconnection agreements should require all new generation resources to have frequency response capabilities as a precondition for connecting with the grid, whether to call for frequency response requirements from existing generators, and whether to establish compensation measures for entities that provide primary frequency response.

Primary frequency response occurs within seconds of an event, and “is critical to the reliable operation” of the bulk power system, FERC said, adding that secondary frequency response can subsequently contribute to stabilizing the grid to address frequency deviations.

The NOI asks a series of questions, including what the costs would be for requiring all new generation resources capable of providing primary frequency response, and what pieces of equipment or software would be needed.

“How would transmission providers verify that new resources provide adequate primary frequency response performance?” and what information is needed to facilitate performance verification, FERC asked.

The NOI also questioned if limitations based on resource type should be considered when evaluating primary frequency response performance.

Comments on the NOI are due 60 days after publication in the Federal Register, FERC said.