By Shaun Rohret, Senior NERC Reliability Specialist
For over ten years, NERC MOD-026-1 was the main reliability standard used to verify that generator excitation and Volt/Var control dynamic models in planning studies matched actual performance. It became effective July 1, 2014, following a FERC order issued in March 2014, and remained enforceable through early 2026. Under MOD-026-1, the compliance emphasis was targeted: verify the model structure and parameters tied to voltage and reactive power controls so dynamic simulations used to assess BES reliability were grounded in real equipment performance.
That focused approach is exactly what MOD-026-2 changes. MOD-026-2 expands the objective from a narrow “excitation/Volt-Var verification” concept to a broader framework to verify and validate dynamic models and associated parameters used in BES reliability assessments. It also widens the scope of facilities explicitly referenced for model accuracy, including generating facilities, transmission-connected dynamic reactive resources, and high-voltage direct current (HVDC) systems, reflecting today’s more diverse and dynamic grid. In practical terms, MOD-026-2 signals that model quality is no longer just a generator-excitation question—it is a system-wide planning necessity tied to multiple technologies and control behaviors.
A second major change is structural: MOD-026-2 consolidates and replaces both MOD-026-1 and MOD-027-1. Previously, “generator model verification” requirements were split between MOD-026-1 for excitation and Volt-Var controls, and MOD-027-1 for turbine/governor and load or active power/frequency control systems. With MOD-026-2, NERC Combined the standards into one, standard rather than two parallel standards that were designed around older technology assumptions. Consistent with that transition, NERC lists both MOD-026-1 and MOD-027-1 as inactive as of March 30, 2026, immediately preceding the new standard’s go-forward period.
The implementation timeline is equally important. NERC shows MOD-026-2 was Board-adopted on October 31, 2025, filed with FERC on November 4, 2025, and approved in a FERC order issued February 19, 2026. The effective date is April 1, 2026. Compliance is phased: certain requirements (R1 and R7) are not required until April 1, 2027 (12 months after the effective date), while other requirements (R2–R6) do not become required until April 1, 2029 (36 months after the effective date). NERC also ties full implementation to the broader Order No. 901 work plan milestones, targeting full implementation by January 1, 2030.
Bottom line: MOD-026-1 specifically addressed verification for excitation and Volt-Var controls, whereas MOD-026-2 combines and broadens these requirements. It replaces both MOD-026-1 and MOD-027-1, establishing a well-defined phased compliance timeline through the years 2027 and 2029, ultimately, leading to full implementation by 2030.
