Understanding the Impacts of IEEE 1547-2018 on Renewable Interconnections
Overview of IEEE 1547-2018
IEEE 1547-2018 is a critical standard for the interconnection and interoperability of distributed energy resources (DER) with electric power systems (EPS). This comprehensive standard outlines technical specifications and requirements for the performance, operation, testing, safety, and maintenance of the interconnection between DER and EPS. It covers various aspects, including general requirements, responses to abnormal conditions, power quality, islanding, and specific test procedures for design, production, installation, commissioning, and periodic evaluations. Applicable to all DER technologies, such as synchronous machines, induction machines, and power inverters/converters, IEEE 1547-2018 primarily focuses on installations in radial primary and secondary distribution systems, with considerations for network distribution systems.[1]
Common Interconnection Requirements
Past renewable interconnections subject to utility witness testing are familiar with the ongoing focus on ensuring a renewable generation facility will “anti-island” properly when the EPS is operating abnormally. “Islanding” is the term used to describe a generator who is capable of operating without a connection to the EPS and forms its own grid frequency and voltage to operate independently. “Anti-islanding” describes the behavior of a generator to cease generating when the EPS becomes unavailable, and grid reference voltage and frequency are abnormal, or lost all together. In its simplest form, during witness testing, Utilities have asked developers to demonstrate at least three operating modes:
When the DER is disconnected from the grid (typically via a TRIP’d recloser), all inverter-based resources (IBRs) should cease generation immediately (no current flow observable at the point of interconnection).
When the DER is reconnected to the grid (typically via a recloser CLOSE), all IBRs should monitor the grid for proper voltage, frequency, and phase rotation before 300s (5m) before starting generation.
Within the reasonable evaluation of the conditions on site and inverter settings, demonstrate to the Utility that the generator is built and configured to only export up to (and not above) the agreed-upon export limit established in the interconnection agreement (IA).
New Requirements Introduced by IEEE 1547-2018
The updated introduces additional requirements for EPS interconnected DER’s that may be required as part of a renewable facility’s technical equipment requirements, telemetry, control, or operational requirements that require additional demonstration during witness testing. The following examples represent some of the new DER requirements being introduced by Utilities as a result of the updated standard:
Anti-Islanding on Loss of Single-Phase
Distribution interconnected DERs, where IBRs are electrically connected through a step-up transformer, often have a difficult time detective loss of single phase on the Utility side of the transformer due the ability for a 3-phase transformer to regenerate voltage on the lost leg.Direct Transfer Trip (DTT)
DTT is the coordination of planned TRIP events between multiple reclosers that are some distance away from each other at the exact same time. By dropping voltage on the entire distribution feeder, from a sub-station to the DER at the end of the line, the Utility is ensured that all generation and load are disconnected in the event a fault happens at the sub-station for safe and controlled re-energization.Active Power Control (APC)
Manifesting in a variety of related requirements, including curtailment, limited export, zero-export, and minimum import requirements; APC required closed-loop control algorithms that increase or decrease the IBR(s) export based on dynamic loads and irradiance levels to ensure an expected export value as measured at the point of interconnection.Automatic Voltage Regulation (AVR)
Manifesting in a variety of operating modes, including PF, voltage, reactive-voltage (VAr), and frequency closed-loop regulation; as well as volt-watt, watt-volt, and watt-VAr curve-based closed-loop operations. These voltage support services are commonly found on transmission level generators connected to the bulk power system (BPS) but are now may be required for distribution level interconnected generators connected at the EPS level as well.Voltage Sag Prevention
Depending on the voltage-stiffness (the ability to maintain a voltage level when subjected to a sudden increase in load) of a distribution feeder, the voltage may sag (or droop) when a DER’s step-up transformers magnetize following restoration of the grid following an outage. Utilities may refer to this power quality characteristic as being caused by “rapid voltage change” (RVC) or “inrush current” that requires reduction.RTU Telemetry
Remote terminal units (RTUs) are a generic term (like computer) that describes a Utility device programmed to securely collect data and possibly send commands as well. Where many Utilities have historically only been able to monitor renewable facility operations via their metering or recloser relays, understanding more about the DER’s specific equipment operations is key to enabling deeper IBR penetration across the EPS. The specific telemetry required often varies by Utility, but the updated standard provides a comprehensive guideline for the parameters, settings, and readings that should be expected.
Aderis Energy's Innovative Solutions
For over a decade, Aderis Energy has been developing and productizing solutions tailored for the very challenges these new requirements introduce for renewable developers, owners, and operators. Aderis’ founders, having first worked in the transmission interconnected renewable projects that broke ground in West, foresaw the inevitable migration of BPS operational requirements to renewable facilities interconnected to the EPS at both distribution and commercial/industrial (C&I) levels. They based this prediction on the increased integration of energy storage on distribution, behind-the-meter DERs for demand reduction, and the development of storage and DERs for virtual power plants.
From inception, Aderis first developed a utility-class monitoring and control system that could be affordably deployed on C&I and distribution projects that currently operates renewable generation facilities ranging from 2kW to over 450MW (AC). “The ability to deliver transmission level control at a price point that was compatible with smaller project budgets is a key differentiator to our company’s ability to offer such flexible solutions for solar, energy storage, and micro-grid customers where are competitors struggle.”, said Brad Micallef, President and CTO. “Acuity, our proprietary edge computer platform, easily scales from monitoring-only single inverter installations, to facilities in the hundreds of megawatts with trackers and string-inverters requiring power plant control and energy storage requirements too.”
Aderis’ solutions extend beyond software, offering a range of hardware products that encompass IEC & CAISO compliant weather stations, UL labeled SCADA enclosures, and a unique modularized pad-mounted interconnection solution, available in the ClearSky product line. “For interconnections ranging in voltages through 35kV, the ClearSky product line provides factory tested and commissioned revenue grade metering, protection relaying, and recloser-capable MV breakers in a single package.”, explained Adam Baker, Director of Product Development. “Unlike other custom switchgear, the ClearSky product line is standardized product, reducing lead-times, keeping costs down, and arriving pre-programmed for single-phase drop testing. For customers with RTU, DTT, PPC, EMS, or just monitoring requirements, the ClearSky arrives ready to host Aderis’ Acuity platform and cellular communications as cost effective options.”
While most solar and storage O&M providers don’t have utility-style lift trucks for overhead medium voltage servicing, the ClearSky’s eye-level installation delivers significant costs throughout commercial operation by making inspections and repairs available to any qualified and authorized personnel.
The ClearSky product line offers yet additional value for customers facing voltage sag mitigation requirements from either RVC or inrush current restrictions. Aderis created the ClearSky PLUS variant that includes Aderis’ own patented whole facility inrush mitigation solution that is fully automated, reliable, and arrives ready-to-run on arrival.
Broad Adoption of IEEE 1547-2018
The updated IEEE 1547-2018 is currently being reviewed and adopted by utility’s, setting technical standards for the interconnection and interoperability of DER with electric power systems to ensure: safety, reliability, and efficiency in integrating renewable energy sources into the grid. Several states, including Massachusetts, Maryland, Pennsylvania, Minnesota, New Mexico, California, and Oregon, have adopted this standard. States like New Jersey, Ohio, Illinois, Wisconsin, Texas, and Colorado are in the process of adoption, while utilities in North Carolina, Tennessee, Louisiana, and Mississippi are also incorporating it.
The Interstate Renewable Energy Council (IREC) tracker indicates which Independent System Operators (ISOs) and Regional Transmission Organizations (RTOs) have adopted IEEE 1547-2018. PJM Interconnection and Alberta System Operator (AESO) are the only North American entities that have completed adoption. The Independent Electric System Operator (IESO) and Hydro-Québec are still undergoing the adoption process, while the Electric Reliability Council of Texas (ERCOT) has an incomplete adoption process. Midcontinent Independent System Operator (MISO) has utility-specific adoption, and New York Independent System Operator (NYISO), Southwest Power Pool (SPP), and California Independent System Operator (CAISO) are in the unclear category.[2]
Aderis Ensures Customers are Ready for the Future
IEEE 1547-2018 is only one of several standards and regulations that add complexity and potential cost to EPS interconnected DERs. Not all of these requirements are impediments, however. FERC 2222, to me implemented by the end of 2026, is geared to open new market opportunities for generators capable of providing grid services, and IEEE 2800-2022 impediments changes to the long-standing requirements that currently turn off inverter grid support capabilities. Aderis is committed to the continual development and innovation of solutions that support the cost effective and rapid deployment of renewable energy as a reliable part of the transition to clean energy.
[1] IEEE Std 1547™-2018
[2] https://www.renewableenergyworld.com/solar/der-solar/here-are-the-states-that-have-adopted-ieee-1547-2018-for-der-interconnection/#gref