Chapter VIII Key Takeaways

Interconnection standards and guidance documents, such as the suite of Institute of Electrical and Electronics Engineers (IEEE) 1547TM standards, play a crucial role in ensuring that devices are interconnected to the grid safely and reliably. They also ensure that they can be reviewed efficiently, since the standards process enables utilities to trust device performance on the grid and minimize the amount of customized review that is required. Chapter VIII: Incorporating Updated Interconnection Standards Into Interconnection Procedures takes a comprehensive look at the existing standards and identifies which standards are relevant to ESS operation. Chapter VIII also provides recommendations on how to incorporate those standards and associated documents into interconnection procedures so that the procedures contain the latest and most relevant technical guidance on ESS design and performance. The project team reviewed eighty-six different standards and related documents for the BATRIES project. Of the eighty-six, the project team found only the IEEE 1547 series, UL 1741 and the Certification Requirement Decision (CRD) for Power Control System, and IEEE C62.92.6 to be relevant to ESS interconnection.

Note: Because the recommendations related to technical standards are deeply technical, they do not lend themselves to a high-level summary. As such, the summary in the table below includes select recommendations only. Readers are encouraged to download Chapter VIII to access the full set of recommendations.

Recommendations for Incorporating Updated Interconnection Standards Into Interconnection Procedures:
UL 1741 Certification Requirement Decisions for Power Control Systems:
 
1. Interconnection applications should be revised to ask whether or not a PCS is included in the DER system design, and if so, require its identification.
 
2. To ensure PCS controls are appropriately addressed, any performance capability should align with or reference UL 1741. Since PCS testing requirements are yet to be published, requirements should note that, in the interim, listing and certification can be fulfilled per the UL CRD for PCS.
 
3. When interconnection procedures require certified equipment, they should require PCS to be certified.
 
IEEE 1547-2018 4.2 Reference Points of Applicability:
 
1. IEEE 1547 defines Reference Point of Applicability (RPA) so that it is clear at what physical point in the configuration of the system the requirements of the standard need to be met for testing, evaluation, and commissioning. It is crucial that the utility and developer agree on the location of the RPA as early as possible to determine the DER system design, equipment, and certification needs. A question should be added to the interconnection application allowing the customer to designate a preferred RPA, which the utility should review.
 
2. The RPA could be reviewed within the Initial Review timeline along with the screens and, for efficiency, the screening process should be completed concurrently with any necessary RPA corrections being made.
 
3. To ensure the RPA is appropriately addressed by technical requirements, any stated selection criteria or commissioning tests should align with or reference IEEE 1547-2018.
 
IEEE 1547-2018 4.6.3 Execution of Mode or Parameter Changes:
 
1. To ensure DERs are appropriately addressed by technical requirements, any stated execution of mode or parameter change performance requirements should align with or reference IEEE 1547-2018.
 
2. If technical requirements specify the execution of mode or parameter changes, include a note stating that those requirements do not apply during islanded operations.
 
3. If technical requirements exist that require control capabilities, include a note stating that those controls do not apply during islanded operation.
 
4. Revise the interconnection application form to include language to help the utility understand if the project plans islanded operation.
 
IEEE 1547-2018 4.7 Prioritization of DER Responses:
 
1. The interconnection evaluation process should include an understanding of any interactions between storage system use cases and export or import limits or other functions. Given the wide range of possible energy storage operating modes, supported modes can be prioritized and documented in the interconnection agreement.
 
2. Manufacturers should list relevant provisions in equipment documentation to enable the above recommendation.
 
IEEE 1547-2018 10 Interoperability, Information Exchange, Information Models, and Protocols:
 
1. To ensure interoperability of ESS is appropriately addressed by technical requirements, any interoperability requirements should align with or reference IEEE 1547-2018.
 
2. When an ESS uses additional parameters beyond those mentioned in IEEE 1547, manufacturers are encouraged to make those setpoints interoperable.
 
3. If IEEE 1547 parameters and setpoints, such as the power factor setpoint and operational state, are needed for ESS in charging mode, they should be specified as applicable to the charging mode in technical requirements.
 
For subclauses IEEE 1547-2018 4.5 Cease to Energize Performance Requirement, 4.6.2 Capability to Limit Active Power, 4.10.3 Performance During Enter Service, 4.13 Exemptions for Emergency Systems and Standby DER, 5.4.2 Voltage-Active Power Mode, and 8.2 Intentional Islanding, either or both of the following are recommended:
 
1. To ensure the issue is appropriately addressed by technical requirements, any related performance requirement should align with or reference IEEE 1547-2018.
 
2. Revise the interconnection application form to give the utility specific information related to the issue.
 
Grid Services:
 
1. To provide certain grid services, ESS may need to provide functionality disallowed by or unaccounted for by IEEE 1547-2018. If specific grid services are allowed, related technical requirements may note all exceptions for IEEE 1547-2018 in a technical requirements document or a grid services contract.
 
2. The interconnection application form should be revised to add a question to flag whether or not grid services will be utilized.
 
Effective Grounding:
 
1. To ensure inverter-based resources are appropriately addressed by technical requirements, any effective grounding requirements for inverter-based resources should align with or reference IEEE C62.92.6, IEEE 1547.2 (once published), and IEEE 1547-2018 subclause 7.4.
 
2. If there are references to grounding reviews in the description of the interconnection studies or related agreements, then interconnection procedures should require the use of IEEE C62.92.6, IEEE 1547.2 (once published), and the test data from IEEE 1547.1-2020 for the review of inverter-based resources.
 
3. If the utility requires supplemental grounding, relevant guidance should be provided in the technical requirements document or interconnection handbook.
 
4. Revise the line configuration screen (SGIP 2.2.1.6) to include new penetration criteria to screen for overvoltage risk.
 
5. Introduce a new Supplemental Review screen or use a tool to determine if supplemental grounding is required. Additionally, an HCA that incorporates evaluation of temporary overvoltage risk for inverters may be used in lieu of the screen mentioned in recommendation 4 above.
 
Referencing Recent Standards in Interconnection Procedures:
 
1. Interconnection procedures should use the most recent versions of the standards discussed in Chapter VIII. Updates to the procedures should account for the timelines associated with the adoption of new or revised standards established by regulatory proceedings.

A. Introduction and Problem Statement

ESS adoption is increasing across the country, and system designs are also rapidly evolving along with the market. Standards related to ESS are changing concurrently or being developed for the first time. Interconnection procedures that fail to incorporate the most recent standards can pose a significant barrier to the cost-effective interconnection of ESS, as well as the effective enablement of the various functionalities that storage can offer. Where standards are either not used, or are outdated, it can be more difficult or impossible for customers to obtain approval to interconnect ESS in a manner that enables storage systems to use their full range of capabilities, or to maximize ESS benefits to customers and grid operators. Utilizing available standards streamlines interconnection by having a common set of requirements across jurisdictions. Importantly, it also allows for third-party certification to the standard and simplifies the process for verifying that ESS will operate in a certain way. Whenever possible, interconnection rules and technical requirements should defer to standards to maximize the benefit of their use.

This chapter identifies areas of interconnection rules where including updates to new or existing standards for interconnected DER (including microgrids) is beneficial for ESS interconnection. Additionally, it reviews topics that are not exclusively related to ESS, such as export control capabilities, to identify how standards could help streamline ESS interconnection. This chapter also explains how the standards facilitate ESS interconnection and provides guidance for regulators seeking to adopt or incorporate the identified standards, with model language where relevant. The recommendations include guidance on how to draft or modify interconnection technical requirements, interconnection procedures, interconnection application and agreement forms, and other related documents.[1]As described in the introduction, recommendations are based on the FERC SGIP as a reference point for developing model language.

The project team reviewed eighty-six different standards and related documents for the BATRIES project. Of the eighty-six reviewed documents, the project team found only the IEEE 1547 series, UL 1741 and the Certification Requirement Decision (CRD) for Power Control Systems,[2]Certification Requirement Decision for Power Control Systems (March 8, 2019), issued for UL 1741, the Standard for Inverters, Converters, Controllers and Interconnection System Equipment for Use with … Continue reading and IEEE C62.92.6 to be relevant to ESS interconnection.

The significance of IEEE 1547 to storage interconnections cannot be understated. For instance, IEEE 1547-2018—the base standard which the other IEEE 1547 series standards complement—establishes the technical criteria for DERs interconnected with the distribution system, covering performance and interoperability requirements for interconnected DERs. As such, IEEE 1547-2018 is the go-to standard for DER installations, including ESS. Complementing IEEE 1547-2018 are:

  • IEEE 1547.1-2020 is the conformance test standard that ensures compliance with the base standard
  • IEEE P1547.2 is a draft guide to applying the base standard and its conformance testing
  • IEEE P1547.9 is a draft guide to using the base standard for interconnection of ESS

The entire IEEE 1547 series of standards and guides (or draft guides) were considered in this chapter. Still, there are some elements within IEEE 1547 where it is unclear how the standard applies to ESS, especially issues related to the bidirectional nature of ESS (charging/discharging) and export control capabilities.

This chapter also describes how to use IEEE C62.92.6-2017 to streamline ESS interconnections and help utility engineers analyze inverter-based DERs. The guide, when used alongside IEEE 1547-2018 and concepts from IEEE 1547.2, aids in the proper evaluation of effective grounding for inverter-based systems.

In addition to IEEE 1547, the UL 1741 CRD for PCS also applies to the interconnection of ESS. The CRD highlights certified control methods within a Power Control System, which can be used to streamline inverter-based DER interconnection. This standard is discussed here and also in Chapter III and Appendix B.

The standards discussed herein most often directly relate to interconnection technical requirements, which interact with rules and regulations in three ways. First, some states include technical requirements in interconnection procedures (see California Rule 21). Second, in some states, regulators approve a separate technical standards document for the entire state (see Minnesota’s Technical Interconnection and Interoperability Requirements), or allow utilities to publish their own technical requirements documents. Third, in some states, no publicly available technical requirements documents exist.

The application of these standards to interconnection rules is fairly nascent, given that interconnection rules evolve slowly and some of the standards were published recently. The below recommendations to use these standards are based on expert opinion, but many are not yet used in state or utility interconnection requirements.

Download the chapter file below to read more. Or download the full Toolkit and Guidance for the Interconnection of Energy Storage and Solar-Plus-Storage for all chapters and recommendations.

References

References
1 As described in the introduction, recommendations are based on the FERC SGIP as a reference point for developing model language.
2 Certification Requirement Decision for Power Control Systems (March 8, 2019), issued for UL 1741, the Standard for Inverters, Converters, Controllers and Interconnection System Equipment for Use with Distributed Energy Resources.

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