Small Generator 'Ride Through' Proposal Draws Favor from Industry Stakeholders
May 30, 2016
By Jasmin Melvin
Industry stakeholders last week appeared mostly on board with a FERC proposal that would require generators smaller than 20 MW to "ride through" and stay connected during abnormal frequency and voltage events.
Large generators already are subject to such a requirement. FERC issued a notice of proposed rulemaking (RM16-8) in March after determining that it would be "unduly discriminatory not to impose these requirements on small generating facilities" in light of the increasing penetration of distributed energy resources on the grid.
Specifically, FERC's proposal would alter the pro formainterconnection agreement for small generators to require those smaller than 20 MW signing up for new interconnection agreements to ride through abnormal frequency and voltage events, rather than disconnecting. The proposed rulemaking would also require transmission providers to coordinate protective equipment settings with automatic load shedding programs.
Industry groups, grid operators and electric reliability coordinators filed comments to FERC May 23 generally agreeing with FERC's position.
The NOPR cited North American Electric Reliability Corp. studies demonstrating the growing impact of small generating facilities on the grid. With technological developments such as smart inverters, these new small generators have the ability to ride through frequency and voltage disturbances like their larger counterparts.
But concerns were posed related to the timing of a new rule going into effect.
The Edison Electric Institute, American Public Power Association, Large Public Power Council and National Rural Electric Cooperative Association, in a joint filing to FERC, supported reforms to the pro forma small generator interconnection agreement (SGIA) but cautioned against imposing broad changes to SGIAs before companies can validate that the changes can be safely implemented into their operating practices.
The trade groups also recommended holding off on finalizing the proposed rule until industry has had an opportunity to address changes to key industry standards being floated to ensure the safe and effective disconnection from utility systems when necessary to avoid islanding conditions. New industry standards from the Institute of Electrical and Electronics Engineers have yet to be approved and in some cases are still unpublished.
"Although the trade associations recognize that some regions, such as California and PJM, had to move more quickly to address changes with respect to distribution interconnection processes in light of renewable portfolio standards, such changes are not in play in all regions of the country at this time," the trade groups said in support of slowing things down. "The commission should acknowledge the many regional differences in how small generators are interconnected."
The groups suggested that while the industry standards undergo review, FERC could convene regional technical conferences "to encourage entities to propose modifications to their individual pro forma SGIA to address their local reliability needs [and to] explore how changes made to the FERC pro forma SGIA may influence state regulations."
NERC, in its comments to the commission, eyed the NOPR as consistent with its reliability assessments.
"NERC has determined that the transforming resource mix may affect reliability of the bulk power system, unless proactive measures are taken to address the integration of greater levels of variable energy and distributed energy resources," it said.
Therefore, it supported "proposals to apply consistent frequency and voltage ride through requirements" as part of interconnection agreements.
Similarly, the ISO/RTO Council warned that "the aggregation or significant combination of small generating facilities that do not ride through transmission disturbances can lead to undesirable consequences for system operations, including causing an otherwise acceptable system post-contingency response to exhibit unacceptable low or high voltage or thermal limit exceedances."
IRC, which filed comments on behalf of the six FERC-jurisdictional independent system operators and regional transmission organizations, said the NOPR was also consistent with wholesale organized markets' tariffs, such as a requirement in ISO New England that all inverter-based generating facilities be able to ride-through voltage disturbances and a PJM Interconnection requirement that all wind units have voltage and frequency ride-through capabilities.
The council commended the proposal for allowing independent entity variations from the proposed revisions, allowing a grid operator, for example, to retain existing provisions in its SGIAs if it could prove the provisions were consistent with or superior to the pro forma agreement changes proposed by FERC.
IRC did recommend clarifying some language in the proposed pro forma agreements to explicitly ensure consistency with NERC reliability standards and any applicable regional entity standards.
Peak Reliability, the reliability coordinator for the bulk of the Western Interconnection, also supported the NOPR, asserting that it would "simplify operational conditions and reduce system load imbalances."
Peak explained that "reductions in system load imbalances may also reduce disturbances on the bulk power system." Further, it said adoption of the proposed rule would "ensure effective protections for system operation while also avoiding increased costs."
The existing pro forma SGIA was adopted in Order 2006 and amended in Order 792. The new requirements would apply to newly interconnecting facilities subject to FERC jurisdiction.
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