Italy (TERNA) — ride-through requirements

The LVRT, HVRT envelopes a grid-scale battery must meet under Italy (TERNA), 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 — Storage plants connecting to the RTN (Terna Allegato A.79).

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; 0.2s → 0 pu; ↗ 2s → 0.85 puverified
high-voltage ride-through (HVRT)ride-through0.001s → 1.3 pu; 0.1s → 1.2 pu; 1s → 1.15 puverified

Where these values come from

  • LVRTTerna Allegato A.79 Rev. 00, Marzo 2023, §6.4 'Insensibilità alle variazioni di tensione', Fig. 1 'Caratteristica FRT per Impianti di Accumulo' and Tabella 1 'Parametri FRT' (tA = 200 ms; tB = 2 s / 2,8 s / 4 s); same values in the June 2022 consultation text (Tabella 2). The code defines a linear recovery ramp; the vertices are read from the clause and the chart draws the segment between them.
  • HVRTTerna Allegato A.79 Rev. 00, Marzo 2023, Fig. 1 'Caratteristica FRT per Impianti di Accumulo' (curva OVRT: 1,3 / 1,2 / 1,15 pu with footnote '1,1 se il punto di connessione è a tensione superiore o uguale 300 kV') and Tabella 1 (tC = 100 ms, tD = 1 s).

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 Italy compares

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

Other grid codes in Europe