FERC Reliability and Resilience

Highlights from the July FERC Open Meeting

August 3, 2016

By Paul Youchak and Taylor Jones , NRDC Summer Interns

FERC Order No. 828

Brief Overview

The Federal Energy Regulatory Commission (FERC) is modifying the pro forma Small Generator Interconnection Agreement (SGIA).  The pro forma agreement establishes standardized interconnection procedures for generating facilities.  The SGIA was first established in 2005 under Order No. 2006 and later amended in 2013 under Order No. 792.  Order No. 828 is looking to rectify a problem that unintentionally arose out of the old Institute of Electrical and Electronics Engineers (IEEE) Standard 1547.  The standard, intended to improve safety conditions at small generators, required distributed generators to disconnect from the grid if voltage or frequency deviated too far from the established set-point. 

The SGIA modifications address changing circumstances in the electricity generation sector.  Distributed and renewable sources of electricity generation are becoming more prevalent on the electricity grid.  And a larger proportion of electricity demand is being met through these small generators.  To help ensure system reliability in the electric grid, the modifications in Order No. 828 require small generating facilities to have the capability to ride through system frequency and voltage disturbances.  The rule adopts the revisions made in IEEE Standard 1547a that allow small generators to have ride through capabilities.

There are three objectives associated with the SGIA modifications:  1) Improve system stability and reliability over the coming years, 2) provide effective protection for system operation while avoiding cost increases, and 3) ensure fair and equitable treatment between small and large generating facilities.

Order Coverage

The SGIA covers generating facilities that are “no larger” than 20 MW.  To comply with the requirements, voltage and frequency are measured at the point of interconnection.  The SGIA applies only to interconnections made subject to a jurisdictional open access transmission tariff (OATT).  States are under no obligation to adopt the provisions in Order No. 828 but the commission hopes that states will look to the order for guidance.

The modified SGIA requirements will apply to all newly interconnecting small generating facilities.  Existing small generation facilities will be covered if they submit a new interconnection request or if they request an unexecuted SGIA filing.  An existing facility that modifies an existing SGIA will also be covered by the new requirements.  To ensure compliance with the rule, each public utility transmission provider that has an SGIA within its OTTA must submit a filing within 65 days, showing the revised requirements for interconnections.

The rule sets out basis performance expectations.  The revisions to the SGIA permit the transmission operator to coordinate with the small generating facility to set appropriate ride through requirements for their situation.  The transmission operator has the flexibility to set appropriate ride through settings while taking into account regional reliability variations and specific conditions at the generating facility.  The rule also requires that small generators must provide successful test completion results to the transmission provider.

Detailed Overview

In America, electricity is transmitted on an alternating current (AC) grid set to operate at 60 or 50 Hz.  To maintain system stability, the grid’s frequency and voltage must be closely controlled.  Deviations from the established set values can be harmful.  For instance, grid equipment may get damaged, consumers may experience performance issues such as flickering lights or, in more serious situations the power system itself may shut down.

To maintain frequency and voltage set-points, electricity production and consumption should be matched.  Since demand is continuously changing, it is impossible to maintain an exact balance in electricity production.  Small imbalances between consumption and supply lead to small deviations in frequency and voltage.  Insufficient production will lower the frequency while excess production will raise the frequency in relation to the set-point.  Small deviations are to be expected and managed but large deviations can cause problems. 

To manage electricity production, transmission operators work to ensure that generators or, in some cases electricity storage facilities, adjust in real time to meet demand and keep frequency deviations small.  Distributed and small generation facilities have traditionally maintained a marginal influence on overall electricity production.  Increasingly, this is no longer the case. 

Traditionally, small generators have been required by IEEE Standard 1547 to automatically disconnect from the grid during significant frequency and voltage deviation events.  If small distributed generators constitute a significant portion of the grids production capacity, automatic disconnecting behavior may cause an operator’s ability to adjust to frequency disturbances more difficult and in turn jeopardize grid reliability.  Order No. 828, and the updated IEEE Standard 1547a, recognizes this and is taking proactive measures to help ensure that the continued penetration of distributed generation facilities does not jeopardize grid stability.  While IEEE Standard 1547a allows but does not require small generators to ride through disturbances, Order No. 828 does require the capability.

Large generating facilities are currently required to ride through frequency and voltage disturbance events.  Order No. 828 also helps to ensure parity in the treatment between the two classes of electricity producers.  Large facilities were otherwise facing an undue burden in ensuring grid stability.  The commission determined that there was no technical or commercial basis to allow small and large facilities to behave differently.  Improvements in technology, particularly small inverters, have made it economically feasible for small generating facilities to ride through frequency disturbance events.  Individual small generators can coordinate with their transmission operators on a case-by-case basis to ensure the safe application of ride through settings.


Requirements for Frequency and Voltage Ride Through Capability of Small Generating Facilities, 18 CFR 35, FERC Order No. 828

Kirby et al., Frequency Control Concerns In The North American Electric Power System, Oak Ridge National Laboratory (2002), http://web.ornl.gov/~webworks/cppr/y2001/rpt/116362.pdf

Performance of Distributed Energy Resources During and After System Disturbance, North American Electric Reliability Council (2003), http://www.nerc.com/pa/RAPA/ra/Reliability%20Assessments%20DL/IVGTF17_PC_FinalDraft_December_clean.pdf


FERC Reaffirms Protections for Small Renewable Power Producers Under PURPA (Docket No EL16-39-000; Order on Petition for Declaratory Order)

In a somewhat unusual ruling, FERC addressed a petition by a small renewable energy developer requesting an enforcement action against the Connecticut Public Utilities Regulatory Authority to remedy the state’s alleged failure to properly implement the Public Utilities Regulatory Policies Act of 1978 (PURPA), by declining to initiate an enforcement action while at the same time issuing a declaratory order affirming the rights of the developer under PURPA. FERC’s declaratory ruling explains that PURPA requires states to guarantee applicable renewables facilities the ability to sell their power pursuant to long-term contracts, at a rate reflecting the costs the relevant utility would have otherwise incurred to supply the power from another source. That rate is only designed to compensate the power producer for the energy or capacity being sold, and not any renewable energy credits (RECs) which might be generated pursuant to state law, leaving producers free to charge more for their RECs or sell them separately. The Commission’s order also explains that a producer’s right to sell power under a long-term PURPA contract cannot be made contingent upon winning a competitive solicitation. Because the developer challenging Connecticut’s implementation of PURPA alleged that the state’s laws do not allow for long-term sales unless the developer wins a competitive solicitation that requires bundling electricity and capacity sales with RECs, FERC’s decision in effect says that if the challenger’s allegations are true, Connecticut’s program violates PURPA. Now that FERC has declined to initiate an enforcement action, the renewables developer is free to bring a challenge in federal court.