NERC PRC-029-1 (IBR) — ride-through requirements

The LVRT, HVRT, FRT envelopes a grid-scale battery must meet under NERC PRC-029-1 (IBR) (US), digitized breakpoint by breakpoint and checked against the clause it came from.

By Sergey Syrvachev — Director of Product Engineering at HyperStrong

Applies to: transmission connections — BES inverter-based resources; valid for RoCoF <= 5 Hz/s.

Part of: the grid-code ride-through chart — compare this against 65 other standards in 44 countries.

What this is, and is not. A reading aid compiled from the clause cited below — not a compliance document. The primary text governs. Every value here was read from a current primary source. Enforceable from 1 Oct 2026 (FERC Order No. 909).

Breakpoints

Times are seconds from the start of the disturbance. Voltage is per-unit of nominal; frequency in hertz. An LVRT curve is a lower boundary (stay connected while voltage is on or above it), an HVRT curve an upper boundary, and FRT gives the band between its High and Low boundaries. These are the boundaries, not the behaviour: what holding one demands of the converter — reactive current injection, thermal stress, protection timing — is stepped through in the LVRT / HVRT ride-through visual.

EventDutyBreakpointsStatus
low-voltage ride-through (LVRT)ride-through0.001s → 0 pu; 0.32s → 0 pu; 0.321s → 0.25 pu; 1.2s → 0.25 pu; 1.201s → 0.5 pu; 3s → 0.5 pu; 3.001s → 0.7 pu; 6s → 0.7 pu; 6.001s → 0.9 puverified
high-voltage ride-through (HVRT)ride-through0.001s → 1.2 pu; 1s → 1.2 pu; 1.001s → 1.1 pu; 1800s → 1.1 pu; 1800.001s → 1.05 puverified
frequency ride-through (FRT)ride-throughHigh: 0.1s → 61.8 Hz; 299s → 61.8 Hz; 299.001s → 61.2 Hz | Low: 0.1s → 57 Hz; 299s → 57 Hz; 299.001s → 58.8 Hzverified

Where these values come from

  • LVRTNERC PRC-029-1, Attachment 1 'Voltage Ride-Through Criteria', Table 2 'Voltage Ride-through Requirements for All Other IBR' (p.12), with Boundary Details bullets 2(b) (PV+BESS → Table 2), 7 and 11 (p.13).
  • HVRTNERC PRC-029-1, Attachment 1, Table 2 'Voltage Ride-through Requirements for All Other IBR' (p.12), rows '>1.20 N/A', '>1.10 Mandatory Operation Region 1.0', '>1.05 Continuous Operation Region 1800'.
  • FRTNERC PRC-029-1, Attachment 2 'Frequency Ride-Through Criteria', Table 3 'Frequency Ride-through Capability Requirements' and Figure 1 'PRC-029 Frequency Ride-through Requirements' (p.14); Requirement R3 caps applicability at RoCoF ≤ 5 Hz/s.

Read it yourself: NERC PRC-029-1 (PDF) ↗

Last checked against the source document on .

How US compares

Each event this code defines, put side by side with every other code that defines it:

Other grid codes in North America