Vietnam BESS (Circular 05/2025/TT-BCT Art. 44) — ride-through requirements

The LVRT, HVRT, FRT envelopes a grid-scale battery must meet under Vietnam BESS (Circular 05/2025/TT-BCT Art. 44), digitized breakpoint by breakpoint and checked against the clause it came from.

By Sergey Syrvachev — Director of Product Engineering at HyperStrong

Applies to: both connections — BESS connecting to the transmission or distribution system.

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.

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; 0.151s → 0.3 pu; 0.6s → 0.3 pu; ↗ 3s → 0.9 pu; 10s → 0.9 puverified
high-voltage ride-through (HVRT)ride-through0.001s → 1.2 pu; 0.5s → 1.2 pu; 0.501s → 1.15 pu; 3s → 1.15 pu; 3.001s → 1.1 puverified
frequency ride-through (FRT)ride-throughHigh: 0.1s → 52 Hz; 60s → 52 Hz; 60.001s → 51.5 Hz; 1800s → 51.5 Hz; 1800.001s → 51 Hz | Low: 0.1s → 47.5 Hz; 600s → 47.5 Hz; 600.001s → 48 Hz; 1800s → 48 Hz; 1800.001s → 49 Hzverified

Where these values come from

  • LVRTCircular 05/2025/TT-BCT dated 1 February 2025, Article 44 clause 3(a)-(c), as consolidated with Circular 46/2025/TT-BCT (in force 22 September 2025); identical envelope at Article 40 clause 6. The code defines a linear recovery ramp; the vertices are read from the clause and the chart draws the segment between them.
  • HVRTCircular 05/2025/TT-BCT dated 1 February 2025, Article 44 clause 3(c), 3(d) and 3(đ), as consolidated with Circular 46/2025/TT-BCT; identical envelope at Article 40 clause 6.
  • FRTCircular 05/2025/TT-BCT dated 1 February 2025, Article 44 clause 1, Table 17, as consolidated with Circular 46/2025/TT-BCT; identical table at Article 40 clause 2, Table 11.

Last checked against the source document on .

How Vietnam compares

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

Other grid codes in Asia-Pacific