ERCOT (NOG 2.9.1.2 legacy) — ride-through requirements

The LVRT, HVRT envelopes a grid-scale battery must meet under ERCOT (NOG 2.9.1.2 legacy) (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 — Transmission IBR with SGIA executed before 1 Aug 2024.

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. Binds resources whose SGIA was executed before 1 Aug 2024.

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; 0.15s → 0 pu; ↗ 1.75s → 0.9 puverified
high-voltage ride-through (HVRT)ride-through0.001s → 1.2 pu; 0.2s → 1.2 pu; 0.201s → 1.175 pu; 0.5s → 1.175 pu; 0.501s → 1.15 pu; 1s → 1.15 pu; 1.001s → 1.1 puverified

Where these values come from

  • LVRTERCOT Nodal Operating Guides Section 2.9.1.2 (applies where the SGIA was executed before 1 Aug 2024): V=0 to 0.15 s then the defined ramp V(t)=0.5625t-0.084375 reaching 0.90 pu at 1.75 s. The code defines a linear recovery ramp; the vertices are read from the clause and the chart draws the segment between them.
  • HVRTERCOT Nodal Operating Guides Section 2.9.1.2 high-voltage table: 1.20 pu / 0.2 s, 1.175 pu / 0.5 s, 1.15 pu / 1.0 s, then 1.10 pu.

Read it yourself: ERCOT Nodal Operating Guides (PDF) ↗

Any event not in the table above is not plotted for this code. Where an absence is itself the finding — a code that defines no high-voltage envelope, or one whose curves circulate under another country's name — it is recorded in the grid codes with no ride-through curve.

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