Grid instability

ID: symptom:grid-instability
IRI: https://solarlattice.org/kb/symptom/grid-instability
Status: active
Also known as: Grid unstable, GRID-INTF, symptom:grid-interference, Grid interference

Grid instability shows up as an inverter alarm. On Solis units it is GRID-INTF, which means the inverter has seen an unstable grid or high internal fault current. First measure the AC voltage and test the AC line for harmonic distortion with the DC switch off. Then repeat the distortion test with the DC switch on. If the distortion is already there with the DC side off, the cause is probably on the grid side. If several inverters share the line, switch one off to see whether they are interacting. An impedance matching adjustment or matching box may help. If the grid looks clean, look for internal damage in the inverter or a wire that came loose during shipping. Sungrow inverters show a similar Grid Abnormal fault and start again once the grid is back to normal. If the fault keeps coming back, measure the grid. Call the local utility if a grid parameter is outside the set range, or Sungrow service if those causes are ruled out.

<!-- review notes

sentence 3: support check: partial - Multiple inverters/turn one off and impedance matching are listed, but the inference that distortion with DC off implies a grid-side cause is not stated.
sentence 4: support check: partial - Internal damage and loose wire in shipping are listed, but the conditional 'if grid looks clean' sequencing is not stated.
sentence 5: support check: partial - Repeated-fault steps (measure grid, utility, Sungrow service) are stated, and the row begins with a fragment about the grid returning to normal, but automatic restart isn't clearly stated and 'similar' comparison is not in the passage. -->

Claims

`observed_as`

c1 drafted · lead High AC line harmonic distortion

The Solis GRID-INTF (grid unstable) alarm guidance says to test the AC line for THD with the DC switch off and again with it on, so distortion on the grid side is the signature to look for.

Solis Manual S5 (75-100)K US V2,3(20230623) tbl=14.r5 h=dc004aa7f58f

review note: support check: partial - Passage supports testing AC line THD for GRID-INTF, but says nothing about the specific signals (phase voltage, current) being distorted or the measurement-type linkage beyond THD testing.

c2 drafted · lead Grid voltage outside limits

For a repeated Sungrow Grid Abnormal fault, measure the actual grid and contact the utility if a grid parameter is outside the set range.

SG250HX-US-UEN-Ver17-202203 tbl=39.r5 h=3c84a7b77032

review note: support check: partial - Passage says to measure the grid and contact the utility if grid parameters exceed the set range, but doesn't mention phase voltage or frequency specifically as outside limits.

c3 drafted · lead Inverter fault code display

Solis and CSI inverters report this condition with the alarm message GRID-INTF01/02, described as grid interference.

Solis_Manual_3P(125-255)K_5G_USA_V1.9(20230620) tbl=14.r12 h=02f61ff2da17
CSI Installation Manual 185-255K USA V1.1 20211119 tbl=12.r12 h=02f61ff2da17
Solis_Manual_RHI-1P(5-10)K-HV_USA_V1.1 tbl=9.r7 h=08b308fe3d39

review note: support check: partial - Alarm text GRID-INTF01/02 and 'Grid interference' are stated, but the passages don't name Solis/CSI brands or say it is observed on the inverter fault code display.

Referenced by

ABB / FIMER PVS-166-175-TL W003 reports c4
ABB / FIMER PVS-60-TL W003 reports c4
ABB / FIMER TRIO-20.0-27.6-TL W003 reports c4
ABB / FIMER UNO-DM-3.3-5.0-PLUS W003 reports c5
ABB / FIMER UNO-DM-6.0-PLUS W003 reports c5
Canadian Solar 125K-T600GL02 GRID-INTF reports c2
Canadian Solar 125KTL-GS-E GRID-INTF reports c2
Canadian Solar 185-255K GRID-INTF01/02 reports c2
Canadian Solar 25-40K-T480GL01 GRID-INTF reports c2
Canadian Solar 25-40KTL-GS-FL GRID-INTF reports c2
Canadian Solar 50-66K-T480GL01 GRID-INTF reports c2
Canadian Solar 50-66KTL-GS-FL GRID-INTF reports c2
Canadian Solar 75-100K-T480GL02 GRID-INTF reports c2
Huawei SUN2000-100KTL-USH0 2038 reports c3
SMA SB-US-41 404 reports c3
SMA SBSE-US-50 404 reports c3
SMA STP-TL-US 404 reports c3
SMA STP-X-US 404 reports c3
SMA SC-CP-XT 404 reports c3
Solis 1P-4G-US GRID-INTF reports c3
Solis 3P-5G-US GRID-INTF01/02 reports c2
Solis RHI-1P-HV GRID-INTF01/02 reports c2
Solis S5-GC GRID-INTF reports c2
Solis S6-EH1P GRID-INTF01/02 reports c2
Solis S6-EH2P G-F-GLU reports c2
Solis S6-EH2P GRID-INTF reports c2
Solis S6-EH2P GRID-INTF02 reports c2
Solis S6-EH3P30-60K G-F-GLU reports c3
Solis S6-EH3P30-60K GRID-INTF reports c3
Solis S6-EH3P30-60K GRID-INTF02 reports c3
Solis S6-EH3P75-150K G-F-GLU reports c2
Solis S6-EH3P75-150K GRID-INTF reports c2
Solis S6-EH3P75-150K GRID-INTF02 reports c2
Solis S6-GC GRID-INTF reports c3
Solis S6-GU GRID-INTF reports c2
Incorrect or unset grid code presents_as c3

Grid instability

Claims

observed_as

Referenced by

Data

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