Frequency ride-through

ID: func:frequency-ride-through
IRI: https://solarlattice.org/kb/func/frequency-ride-through
Status: active
Also known as: LFRT/HFRT, LFRT, HFRT, Low/High Frequency Ride-Through, FRT_US
Category: Grid support
Function kind: grid-support

Frequency ride-through lets an inverter keep running through abnormally low or high grid frequency for a set time, and disconnect only if the excursion lasts longer than that delay. PPL EU publishes shall-trip settings for frequency ride-through: UF1 at 58.5 Hz and OF1 at 61.2 Hz, each with 301 s clearing, plus UF2 at 56.5 Hz and OF2 at 62 Hz, each with 0.2 s clearing. On the Solectria SGI XTM, LFRT and HFRT are set over Modbus with up to 10 ordered pairs of frequency percent and time. Each can be enabled on its own, and once enabled it overrides the UL1741/IEEE1547 frequency protection setpoints.

<!-- review notes

sentence 3: support check: partial - Ordered pairs (up to 10), separate enabling and override of UL1741/IEEE1547 setpoints are stated, and registers are Modbus-style offsets, but Modbus is never explicitly named. -->

Parts

Claims

`trip_threshold`

c1 drafted · lead nominal 58.5 HZ

Conditions: PPL EU required under-frequency shall-trip setting UF1

DER Ride Through Settings [code/standard] tbl=4 h=d45e5447a687
DER Ride Through Settings [code/standard] tbl=4.r3 h=51e8170b07de

review note: possible conflict with c3 (same source; check the conditions); possible conflict with c5 (same source; check the conditions); possible conflict with c7 (same source; check the conditions)

c3 verified · fact nominal 56.5 HZ

Conditions: PPL EU required under-frequency shall-trip setting UF2

DER Ride Through Settings [code/standard] tbl=4 h=d45e5447a687
DER Ride Through Settings [code/standard] tbl=4.r4 h=3392dc7c64a1

verified by: review-workflowverified on: 2026-10-24review note: possible conflict with c1 (same source; check the conditions); possible conflict with c5 (same source; check the conditions); possible conflict with c7 (same source; check the conditions)

c5 drafted · lead nominal 61.2 HZ

Conditions: PPL EU required over-frequency shall-trip setting OF1

DER Ride Through Settings [code/standard] tbl=5 h=356df394eec9

review note: possible conflict with c1 (same source; check the conditions); possible conflict with c3 (same source; check the conditions); possible conflict with c7 (same source; check the conditions)

c7 drafted · lead nominal 62 HZ

Conditions: PPL EU required over-frequency shall-trip setting OF2

DER Ride Through Settings [code/standard] tbl=5 h=356df394eec9
DER Ride Through Settings [code/standard] tbl=5.r4 h=4eda35ca959e

review note: possible conflict with c1 (same source; check the conditions); possible conflict with c3 (same source; check the conditions); possible conflict with c5 (same source; check the conditions)

`trip_time`

c2 drafted · lead nominal 301 SEC

Conditions: PPL EU UF1 clearing time at 58.5 Hz

DER Ride Through Settings [code/standard] tbl=4 h=d45e5447a687
DER Ride Through Settings [code/standard] tbl=4.r3 h=51e8170b07de

review note: possible conflict with c4 (same source; check the conditions); possible conflict with c8 (same source; check the conditions)

c4 verified · fact nominal 0.2 SEC

Conditions: PPL EU UF2 clearing time at 56.5 Hz

DER Ride Through Settings [code/standard] tbl=4 h=d45e5447a687
DER Ride Through Settings [code/standard] tbl=4.r4 h=3392dc7c64a1

verified by: review-workflowverified on: 2026-10-24review note: possible conflict with c2 (same source; check the conditions); possible conflict with c6 (same source; check the conditions)

c6 drafted · lead nominal 301 SEC

Conditions: PPL EU OF1 clearing time at 61.2 Hz