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Understanding interconnection of distributed energy resources (DERs)

By Jason Allnutt

The growth in distributed energy resources presents huge opportunities both in front-of-meter and behind-the-meter but the process of interconnection to the grid could still be a lot smoother, Jason Allnutt, Conformity Assessment Program Specialist for the IEEE Standards Association says.

Adoption of distributed energy resources (DERs) is surging around the world. DERs are bringing unique benefits to the global energy landscape that central-station power plants and long-distance transmission and distribution alone could not. DERs allow for power to be generated when and where it is most needed, and decentralising power production can contribute to a dramatically more secure and resilient facility for electricity delivery. DERs interconnected with the grid position a utility to better manage peak demand, avoid transmission overloads and keep electricity flowing to its customers.

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But interconnection of battery, combined heat and power (CHP), solar, wind, and other DERs is not without its challenges. For example, utilities, DER developers, and DER owners are not always on the same page in terms of precisely how to undertake an installation and who is responsible for which part in the interconnection process. Furthermore, there is a constant debate among utilities, commercial customers and public utility commissions (PUCs) around interconnection rules. Major outages usually amplify these sorts of misunderstandings.

It is crucial that stakeholders across the DER landscape share a common understanding of DER interconnections—especially with regard to what needs to be done by whom during installation and in the field. While type and production testing is well defined and executed by manufacturers’ or independent test laboratories, field work such as commissioning and verification vary widely across different organisations and jurisdictions, and the result can be frustrating with costly delays and missteps.

Reliable DER guidance

IEEE 1547™, IEEE Standard for Interconnection and Interoperability of Distributed Energy Resources with Associated Electric Power Systems Interfaces, is an essential resource for the wide range of DER stakeholders:

  • Owners, planners, designers and operators of electric power systems

  • Electricity consumers

  • Equipment manufacturers

  • System integrators

  • DER personnel

  • Energy efficiency and demand response planners

  • Regulatory and government bodies

The standard offers technical guidance for interconnection and interoperability among utility electric power systems and DERs of all types and sizes. In addition to covering general requirements, IEEE 1547 also addresses key specifics such as islanding, power quality, response to abnormal conditions and test specifications and requirements for design, production, installation evaluation, commissioning and periodic testing of DERs.

Utility electric-power systems were not originally engineered to connect with active DERs. The product of a balanced, globally open consensus development process, IEEE 1547 was initially published in 2003 and proposed the first performance, operation, testing, safety, and maintenance criteria and requirements for DER with aggregate capacity of 10 Megavolt-Ampere (MVA) or less at the point of common coupling. Legislation (for example, the US Energy Policy Act of 2005), regulatory deliberations and utility engineering and business practices worldwide have often cited the standard in the years since.

During that time, too, the standard steadily has evolved in a regular cycle of revisions to keep out in front of new DER market challenges, opportunities, and technology innovation as systems for electricity delivery have grown more digital and more controllable. The standard was most recently revised in 2018, and global growth of DER grid interconnections was a leading influence in IEEE 1547’s newest modifications. The US National Association of Regulatory Utility Commissioners (NARUC) in 2020 approved a resolution that recommended its member regulatory agencies such as state PUCs to engage stakeholders to adopt 1547-2018.

And, yet, exactly how IEEE 1547 is leveraged in informing DER interconnections from market to market is not consistent, which is understandable given the significant regional differences in DER reliance. Some jurisdictions are only at the outset of adoption. Others already have achieved significant implementation milestones—such as boosted requirements for changeover to renewables, regulatory changes around leasing and net-metering, incentives for buildout of small-scale commercial and residential DER systems, introduction of neighborhood-based virtual power plants of interconnected DERs and/or DER-based microgrids, etc.

Consistency in interconnection

The IEEE Conformity Assessment Program (ICAP), a programme of IEEE Standards Association (IEEE SA), is working with several utility partners—Baltimore Gas and Electric Company (BGE), Commonwealth Edison (ComEd), Dominion Energy, Duke Energy,and Orange & Rockland Utilities (O&R)—to develop a certification programme to bring clarity and consistency to DER interconnections. In addition to providing documentation for a uniform IEEE 1547 commissioning process and other DER-interconnection educational materials, the IEEE 1547 Distributed Energy Resources (DER) Interconnection: Education and Credentialing Program is intended to enable identification, training, and certification of qualified individuals for commissioning of installed DER interconnections.

In such ways, the forthcoming IEEE programme is intended to benefit professionals who do field work on electrical systems, inspectors, utility commission engineers, engineering firms that provide commissioning services, and other professionals  involved in the DER interconnection process. Utilities will be an especially crucial benefactor, as adopting the programme will help expand their access to independent, trained, and credentialed professionals to perform commissioning, without taking on the organizational burden of having to train and maintain this resource themselves.

DER stakeholders around the world are encouraged to visit the IEEE 1547 Distributed Energy Resources (DER) Interconnection: Education and Credentialing Program or reach out to [email protected] to learn more and contribute to the programme’s development.

Cover Image: Distributed energy resources like solar combined with batteries are bringing unique benefits to the global energy landscape that central-station power plants and long-distance transmission and distribution alone could not. Image: Brooklyn Microgrid via Facebook. 

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