The Federal Energy Regulatory Commission (FERC) is proposing new reliability requirements that will apply to renewable and storage resources. On November 17, 2022, FERC issued a Notice of Proposed Rulemaking ("NOPR") to address various reliability concerns related to the increasing number of inverter-based resources ("IBRs") on the electric grid.  As used in the proposed rule, IBRs may refer to solar photovoltaic, wind, fuel cell, and battery storage resources. FERC noted that current electric reliability standards enforced by the North American Electric Reliability Corporation ("NERC") (the "Reliability Standards") do not fully assess the impacts of IBRs on the reliability of the Bulk-Power System ("BPS")discussed below.
In FERC's view, the current Reliability Standards were developed to apply mainly to synchronous generation resources that convert mechanical energy into electric energy through electromagnetic induction,and do not account for the material technological differences between the response of synchronous generation resources and IBRs (particularly with regard to system disturbances). For example, FERC noted that while synchronous generators will normally ride through a system disturbance automatically, IBRs must be programmed to support the electric power system and to ride through a disturbance, prompting new considerations for transmission planning and operation of the BPS.
FERC recognized the following reliability gaps in the current Reliability Standards with regard to IBRs:
Current Reliability Standards – Reliability Gaps
- IBR Data Sharing
FERC stated that the current Reliability Standards do not ensure that IBR owners and operators consistently provide accurate and complete IBR Data. Specifically, FERC observed that the current Reliability Standards do not ensure that transmission planners and operators receive modeling data and parameters from all BPS generation resources necessary to create and maintain valid individual registered IBR models used to perform steady-state, dynamic, and short circuit studies. Additionally, the current Reliability Standards do not ensure that transmission planners and operators receive modeling data and parameters regarding unregistered IBRs and IBR-DERs and disturbance monitoring data regarding all generation resources capable of having a material impact on the reliable operation of the BPS, including IBRs.
- IBR Model Validation
FERC opined that once planners have IBR Data, they must ensure the accuracy of such data to create valid system models. Currently, the BES definition, which identifies the entities required to comply with the Reliability Standards, does not include unregistered IBRs or inverter-based resources connected to the distribution system, which the NOPR refers to as "IBR-DERs." Hence, the current Reliability Standards do not address the provision by unregistered IBRs or IBR-DERs of aggregate modeling data and parameters and lack IBR-specific modeling data and parameters. This leads to a tedious process which requires IBR operators to coordinate with: (a) registered IBR generator owners and operators; (b) transmission owners that have unregistered IBRs connected to their systems; and (c) distribution providers that have IBR-DERs to obtain IBR specific modeling data and parameters so that the transmission planners and operators can validate the accuracy of such data to create meaningful models of steady-state and dynamic and short circuit models for registered IBRs, unregistered IBRs, and aggregate IBR-DERs.
- IBR Planning and Operational Studies
Once planners and operators validate system models, they must include those models in planning and operational studies to assess the reliability impacts of both individual and collective IBRs on BPS performance. The current Reliability Standards do not ensure that planning and operational studies assess the performance and behavior of both individual and aggregate registered IBRs and unregistered IBRs, as well as IBR-DERs in the aggregate. Hence, FERC found that this reliability gap in planning assessments may lead to false expectations that system performance requirements are met and may inadvertently mask potential reliability risks in BPS planning and operations.
- Registered IBR Performance
The current Reliability Standards do not account for the difference between the response of registered IBRs and synchronous generation resources during normal and contingency conditions. For example, FERC found that the current Reliability Standards do not include frequency ride through performance requirements that address the unique protection and control functions of IBRs. FERC also observed that the current Reliability Standards do not require registered IBRs to continually produce real power and support voltage inside the "no trip zone" during a voltage excursion. Notably, FERC determined that the current Reliability Standards do not have voltage ride through performance requirements that address the unique protection and control functions of registered IBRs that can cause tripping and momentary cessation, even when the IBR voltage protection settings are compliant with the Reliability Standards.
- IBR Data Sharing
To address a perceived data sharing gap related to IBRs, FERC directed NERC to develop new/modified standards that identify, among other elements: (a) the registered entities that must provide certain data of registered IBRs, and unregistered IBRs and IBR-DERs, in the aggregate; (b) the minimum categories and types of IBR, non-registered IBR, and IBR-DER data that must be provided; and (c) the timing and periodicity for the provisions of modeling, operations, and disturbance analysis to reviewing entities. FERC also directed NERC to adopt new/modified standards that require registered IBRs to provide complete and accurate IBR-specific modeling data and parameters (e.g., steady-state, dynamic, and short circuit modeling information, and control settings for momentary cessation and ramp rates) to planning coordinators, transmission planners, and other parties responsible for planning and operating the BPS.
- IBR Model Validation
NERC was also directed to ensure that new/modified standards require: (a) generator owners to provide validated registered IBR models to the planning coordinators for interconnection-wide planning and operational models; (b) transmission owners to provide validated unregistered IBR models to planning coordinators for interconnection-wide planning and operation models; and (c) distribution providers to submit validated models for IBR-DERs in the aggregate to planning coordinators for interconnection-wide planning and operation models. FERC further proposed that NERC require registered IBRs, and transmission owners with unregistered IBRs on their systems, to ensure that dynamic models provided to system planners represent the dynamic performance of registered IBRs and unregistered IBR facilities, including momentary cessation and/or tripping, including all ride through behavior.
- IBR Planning and Operational Studies
With regard to planning studies, FERC directed that the new/modified standards should require planning coordinators and transmission planners to include in their planning assessments the study and evaluation of performance and behaviors of individual and aggregate registered IBRs, and unregistered IBRs and IBR-DERs in the aggregate, under normal and contingency system conditions in their planning area. The planning assessments are to include the study and evaluation of the ride through performance (i.e., tripping and momentary cessation conditions) of such IBRs in their planning area for stability studies on a comparable basis to synchronous generation sources.
With regard to operational studies, FERC directed NERC to adopt new/modified reliability standards that would require: (a) reliability coordinators and transmission operators to include the performance and behavior of both individual and aggregate IBRs, unregistered IBRs and IBR-DERs in their operational analyses, real-time monitoring, and real-time assessments, including non-BPS data and external power system network data identified in their data specifications; and (b) balancing authorities to include the performance and behaviors of both individual and aggregate registered IBRs and unregistered IBRs and IBR-DERs in their operation analysis functions and real-time monitoring.
- Registered IBR Performance
Noting that it is important for registered IBRs to support essential reliability services during system disturbances, FERC directed NERC to develop new/modified standards that would require generator owners and operators to ensure that their registered IBR facilities ride through system frequency and voltage disturbances where technologically feasible. In a related directive, FERC ordered that these new/modified standards should reflect the technological differences and technical capabilities between registered IBRs and synchronous generation sources in order for IBRs to provide support for these essential reliability services.
FERC further directed new/modified standards that would require: (a) that registered IBRs' post-disturbance ramp rates not be restricted so as to not artificially interfere with the resource returning to pre-disturbance output levels in a quick and stable manner after a BPS fault event; and (b) IBRs to ride through any conditions not addressed by the proposed reliability standards that address frequency or voltage ride through phase locked loop synchronization.
FERC directed NERC to present the new/modified Reliability Standards in a staggered fashion pursuant to a FERC-approved implementation plan (the "Plan") with the following priorities:
- standards addressing IBR failures to ride through frequency and voltage variations during normally cleared BPS faults – 12 months after FERC approval of the Plan
- standards addressing data sharing and model evaluation among and between registered IBRs, non-registered IBRs, and IBR-DERs – 24 months after FERC approval of the Plan
- standards addressing post-disturbance ramp rates and phase-locked loop synchronization – 36 months after FERC approval of the Plan
NERC was directed to submit the proposed Plan to FERC for approval within ninety (90) days of the FERC's adoption of a Final Rule in this proceeding.
In the NOPR, and in related FERC issuances, NERC has acknowledged a number of valid concerns with regard to the influx of IBRs in the country's changing BPS mix. These stated concerns, which have been culled from – among other sources – a careful study of documented and serious system disturbances involving IBRs, are foundational. Indeed, FERC has invited stakeholders to supplement FERC's expressed objectives and test the operational and functional limits of IBRs. Given the scope of the new/modified standards directed by FERC, and the timing for implementing the development and adoption of these standards (which process may be slowed by regulatory and judicial challenges asserting NERC's limited role in requiring IBRs outside of the BPS to provide any data or other cooperation), there is a concern that system disturbance events may overtake sound regulatory intentions. Because the influx of IBRs is set to continue unabated, there may be little time to wait for regulatory outcomes. Industry stakeholders, including system planners and operators and owners and operators of IBRs, should be preparing for greater IBR operational scrutiny and reporting, and should – where feasible – consider voluntary and cooperative data sharing and modelling efforts to ensure the reliability of the BPS while FERC's ordered reliability standards navigate through a multi-year approval process.
Comments on the NOPR are due on February 6, 2023.
 Reliability Standards to Address Inverter-Based Resources, 181 FERC ¶ 61,125 (2022) ("NOPR").
 NOPR at P 1.
NERC defines "essential reliability services" to include "necessary operating characteristics" provided by "[c]onventional generation with large rotating mass," which are "needed to reliably operate the North American electric grid." NOPR at fn 171.
 NOPR at P 12.
 NOPR at P 3.
 IBR Data is defined in the NOPR as information related to the location, capacity, telemetry, steady-state, dynamic and short circuit modeling information, control settings, ramp rates, equipment status, disturbance analysis data, and other information about IBRs.
 NOPR at P 29.
 NERC's Commission-approved BES definition is a subset of the BPS and defines the scope of the NERC Reliability Standards and the entities that are required to comply with those standards. The FERC-approved BES definition includes a "bright line" for identifying all transmission elements operated at 100 kV or higher and real and reactive power resources connected at 100 kV or higher. Where necessary to qualify the proposed directives, FERC differentiates between IBRs registered with NERC and therefore subject to the Reliability Standards because they fall within the BES definition (registered IBRs) from those connected directly to the BPS but not registered with NERC, and therefore not subject to the Reliability Standards (unregistered IBRs) and those connected to the distribution system (IBR-DER). Revisions to Elec. Reliability Org. Definition of Bulk Elec. Sys. & Rules of Proc., Order No. 773, 78 FR 804 (Jan. 4, 2013), 141 FERC ¶ 61,236 (2012) order on reh'g, Order No. 773-A, 78 FR 29209 (May 17, 2013), 143 FERC ¶ 61,053 (2013) rev'd sub nom., People of the State of N.Y. v. FERC, 783 F.3d 94 6(2d Cir. 2015); NERC, Glossary of Terms Used in NERC Reliability Standards, 5-7 (Mar. 29, 2022), https://www.nerc.com/pa/Stand/Glossary%20of%20Terms/Glossary_of_Terms.pdf (NERC Glossary).
 NOPR at P 35.
 NOPR at P 48.
 NOPR at P 56.
 NOPR at P 60.
 NOPR at P 61.
 Tripping offline is a mode of operation during which part of or the entire IBR disconnects from the BPS and/or distribution system and therefore cannot supply real and reactive power. Momentary cessation is a mode of operation during which the inverter remains electrically connected to the BPS, but the inverter does not inject current during low or high voltage conditions outside the continuous operating range. As a result, there is no current injection from the inverter and therefore no active or reactive current (and no active or reactive power). NERC, Reliability Guideline: Bulk-Power System-Connected Inverter-Based Resource Performance, 11 (Sept. 2018), https://www.nerc.com/comm/RSTC_Reliability_Guidelines/Inverter-Based_Resource_Performance_Guideline.pdf (IBR Performance Guideline). NOPR at fns 9 and 10.