As part of the Notice of Proposed Rulemaking (NOPR) on generator interconnection, FERC proposed that co-located resources can share an interconnection request, was convinced about the “fuel-based dispatch” to reduce the instances of expensive network upgrades for worst-case interconnection studies, and expanded ride-through requirements to include under-voltage and over-voltage conditions.
There are three controversial requirements in this final component of the FERC interconnection NOPR. First, FERC requires transmission providers to terminate an agreement with the interconnection customer if a hybrid resource didn’t operate as intended. Second, transmission providers must evaluate alternative transmission technologies only when the interconnection customer requests. And third, interconnection customers must provide detailed modeling data to transmission providers; otherwise, the interconnection request is considered withdrawn.
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1. Shared interconnection requests for hybrid projects
FERC defines hybrid resources as co-located, share a point of interconnection, and proceed through the generator interconnection process with a single interconnection request.
Before proposing requirements, FERC takes a trip down the memory lane to FERC Order 2003, where it didn’t foresee hybrid resources (energy storage co-located at solar interconnection) taking up much space in current interconnection queues.
FERC proposes memorializing co-located resources in Large Generator Interconnection Procedures (LGIP). FERC proposes requiring transmission providers to allow more than one resource to co-locate on a shared site behind a single point of interconnection and share a single interconnection request. But FERC doesn’t guide transmission providers on what to do with current hybrid resources in the queue.
In addition to defining co-located resources and their ability to share an interconnection request, FERC’s proposal modifies the definition of site control to allow interconnection customers to demonstrate shared land-use for generating facilities that include more than one resource. Lastly, FERC proposed that co-located resources are responsible for ensuring there are no voltage differences among the technologies.
2. Revisions to the material modification process
From the ISO informational reports submitted as part of the hybrid resource proceeding, FERC learned that when an electric storage resource is added at a solar interconnection, PJM considers it a material modification.
In contrast, CAISO doesn’t consider it a material modification because any transmission congestion resulting from energy storage injection is considered “non-material” if it doesn’t change the requested interconnection service level.
So, FERC’s proposal requires transmission providers to evaluate the proposed addition of a generating facility to an interconnection request as long as the interconnection customer does not request a change to the originally requested interconnection service level. FERC said the transmission provider cannot automatically consider such a request a material modification.
Lastly, FERC is seeking comments on whether a full interconnection service study is required in situations when a generator does not alter the final interconnection service level. FERC is also asking for comments when storage is charging and if it changes the electrical characteristics of an interconnection request.
3. Availability of surplus interconnection service
FERC defines surplus interconnection service as “any unneeded portion of Interconnection Service established in a Large Generator Interconnection Agreement, such that if Surplus Interconnection Service is utilized the total amount of Interconnection Service at the Point of Interconnection would remain the same.”
MISO has received 14 surplus interconnection requests so far this year. All of them are adding storage to existing solar and wind interconnection requests.
FERC required transmission providers to allow interconnection customers to access the surplus interconnection service process once the original customer has an executed LGIA or during the filing of an unexecuted LGIA. FERC eliminated the restriction that only those interconnection customers that have achieved commercial operation have access to surplus interconnection capacity.Grissom Solar, a 6.9MWdc solar plus storage project in Enfield, NC. Image: Pine Gate Renewables
4. Making operating assumptions
In proposing requirements for operating assumptions for hybrid projects, FERC considered that multiple RTOs/ISOs rely on worst-case operating assumptions such as the electric storage resources charge during peak load periods and discharge when the load is light. FERC heard that these worst-case operating assumptions could lead to expensive network upgrades in the interconnection studies.
FERC referenced Hybrid Resources Coalition and Pine Gates’s comments in modeling hybrid resources. FERC was also sold on Enel’s comments about “fuel-based dispatch” – solar would produce more in the summer, the wind would produce more in the winter, and if both were studied for peak output, then a network upgrade would be triggered. But if solar peak output was only considered for summer months and wind output was only considered for winter months – it would not create the need for that expensive network upgrade. FERC noted that both MISO and PJM use this dispatch.
FERC is proposing to require transmission providers, at the request of the interconnection customer, to use operating assumptions for interconnection studies that reflect the proposed operation of an electric storage resource or co-located resource containing an electric storage resource (including hybrid resources).
FERC also proposes to hold the interconnection customer accountable for what they say about the intended operation of the hybrid resource. If the interconnection customer fails to operate hybrid resources as intended, the transmission provider can terminate the LGIP agreement.
Lastly, FERC seeks comments on whether it should expand the proposal to include definitions for peak load period, firm and non-firm charging for electric storage resources, and require transmission providers to define study criteria and possible ways to interconnect related to both firm and non-firm charging.
5. Alternative transmission technologies
FERC has not made up its mind yet on the feasibility of new transmission technologies as viable alternatives to network upgrades. That is my conclusion because FERC has started distinguishing grid enhancing technologies and alternative transmission technologies.
FERC received many comments in the ANOPR to require grid enhancing technologies (GETs) to reduce the need for expensive network upgrades. But for this NOPR, FERC has decided to focus on alternative transmission technologies defined as “advanced power flow control, transmission switching, dynamic line ratings, static synchronous compensators, and/or static VAR compensators.”
FERC is not proposing many requirements in this aspect of NOPR. Rather, FERC seeks comments from stakeholders on a couple of requirements. It requires the transmission provider to study alternative transmission solution(s) during the cluster study upon receiving a request from the interconnection customer. And it is proposing revisions to both large and small generator interconnection procedures to include alternative transmission technologies consideration.
FERC is seeking comments on various topics related to alternative transmission technologies, including barriers to using these technologies, whether those technologies could effectively provide the same transmission service as a traditional network upgrade, and whether the existing studies and models are suitable.
FERC also sought comments on who pays for the evaluation of those alternative technologies and whether they should be shared among interconnection customers in the cluster, and what is the reasonable number of study requests from each interconnection customer so that the transmission provider is not bogged down, and whether provisional interconnection service for these technologies should be considered mandatory.
6. Annual informational report
FERC is also seeking comments on whether FERC staff should put together an annual informational report that documents how transmission providers evaluate alternative technologies and open a new docket to document all these lessons learned so that interconnection customers can benefit from the transparency.
7. Modeling and performance requirements for non-synchronous generating facilities
Before expanding ride-through requirements for non-synchronous (solar photovoltaics, wind, fuel cell, and battery storage) facilities, FERC lays the groundwork by discussing past events where solar failed to perform.
FERC’s timeline started with the first large-scale event in 2016 with the Blue Cut Fire, then followed up with the Canyon 2 Fire Event in 2017, the Angeles Forest and Palmdale Roost Events in 2018, the San Fernando Disturbance in 2020, and multiple events in both ERCOT and CAISO during 2021. The bottom line is that FERC is concerned about non-synchronous units tripping or entering momentary cessation mode.
An anomaly in FERC’s proposal at this stage in NOPR is that even though FERC doesn’t discuss past modeling issues or challenges, FERC proposed that all interconnection customers seeking to interconnect non-synchronous units provide the modeling information necessary for the transmission provider to conduct interconnection studies.
FERC justifies the modeling requirement based on potentially skewed interconnection costs if the transmission provider doesn’t have the right information to identify interconnection facilities and network upgrades needed to interconnect renewable projects safely.
Before moving on to ride-through requirements, it is worth noting that FERC proposed that a queue project is considered withdrawn if the interconnection customer fails to provide the data to the transmission provider after a 10-day grace period. FERC seeks comment on this modeling requirement and asks if it is necessary and sufficient to model non-synchronous facilities accurately.
8. Ride-through requirements
FERC largely follows NERC Inverter Based Resources (IBR) performance guidelines to propose ride-through requirements for all new generator interconnection projects. In this NOPR, FERC proposed to expand the definition of “ride-through” from under-frequency and over-frequency conditions to include the ability of the large generating facility to stay connected to and synchronized with the transmission system during system disturbances within under-voltage and over-voltage conditions as well.