A variety of work products can be found on this page. unifi specifications for GFM IBRs are leading the industry forward with guidelines for modeling, analysis, installation, and verification. unifi modeling and simulation libraries for GFM IBRs are found in various domains and in leading software tools. We are also developing GitHub implementation and validation repositories for rapid prototyping of GFM hardware.

On this page:

Specifications for Grid-forming Inverter-based Resources

Cover of Unifi's "Specifications for Grid-forming Inverter-based Resources, Vol 1."

Specifications for Grid-forming Inverter-based Resources, Version 2

This document defines a set of specifications for GFM IBRs that provides requirements from both a power system-level as well as functional requirements at the inverter level that are intended to provide means for vendor-agnostic operation of GFM IBRs at any scale in electric power systems. The specifications are clearly identified and attributed to an IBR plant or an IBR unit throughout the document, where applicable. The specifications are authored by stakeholders from across the industry.

Modeling & Simulation Libraries / Software

Models developed by the unifi modeling & simulation team continue to be adopted across the industry.  Some examples of electromagnetic-domain and positive-sequence models for GFM IBRs are given below:

PS CAD logo.

EMT models of PV inverter based resource in GFL and GFM mode.  Model includes an interoperable primary control grid forming system architecture that is designed for use with both individual IBRs and aggregations.  The design is intended to coexist with vendor specific proprietary controls that exchange standardized signals with the system operator to regulate frequency and voltages, or to manage black start.

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WECC logo.

The model specifications of droop-based GFM (REGFM_A1) and VSM-based GFM (REGFM_B1) have been adopted by WECC. The model specifications can be accessed through the following links. The REGFM_A1 model has already been released in major commercial transient stability simulation tools including PTI-PSS®E, GE-PSLF, PowerWorld Simulator, and TSAT. The REGFM_B1 model is expected to be released in those tools soon.

Download Model Specification – REGFM_A1 PDF →

Download Model Specification – REGFM_B1 PDF →

EMTP logo.

Generic EMTP model for a three-phase aggregated grid-forming inverter (GFM inverter).  Applications include stability, fault, harmonic, dynamic, and interconnection studies.  The GFM inverter can be modeled as: droop- based, virtual synchronous machine (VSM)-based, dispatchable virtual oscillator (dVOC)-based, or a PLL-based.

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Power World Corporation logo.

Control blocks of REGFM_A1 and REGFM_B1.

GitHub Implementation & Validation Repository

Coming soon…