Grid parameters out of range

The inverter reports a grid warning, for example W003 Grid Fail with a yellow LED, when grid voltage or frequency goes beyond the limits set by the operator during normal operation. Possible triggers are an absent grid voltage, after which the inverter shows Missing Grid, an unstable voltage that is too low or too high, or an unstable grid frequency. The alarm relay switches while W003 to W007 are present and resets when the signal ends, because checking the grid is normal operation and not an alarm state. Check the grid voltage first at the inverter and then at the supply point. If it is absent at both, the problem is on the grid side. If the voltage rises only while the inverter is exporting, or is high at the supply, the line or grid impedance is high. Ask the utility to adjust the voltage, and change inverter limits only with their approval and with customer assistance. If the voltage at the supply point is much lower than at the inverter, the line between the inverter and the contactor needs attention. If voltage stays high, the inverter may first reduce output power and later disconnect if a 10-minute average stays out of range. Check whether the protection settings suit the selected grid standard.

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• sentence 4: support check: partial - The passages say to check at the inverter and then at the supply point if absent, but they do not say that absence at both means the problem is on the grid side.
• sentence 5: support check: partial - High impedance and asking the operator to adjust voltage are stated, but 'utility' is not named, and 'only while exporting' is a stronger reading than 'tends to rise when connected'.
• sentence 7: support check: partial - Power limiting then disconnection on a 10-minute average is stated, but checking protection settings against the grid standard is only loosely supported (the standard-dependent U< and U> values, and the Sungrow protection-parameter check for underfrequency).
• sentence 4: review: partial - The order of checks (inverter first, then the supply point) is stated, but the conclusion that absence at both means a grid-side problem is not.
• sentence 7: review: partial - Power limiting followed by disconnection on an out-of-range 10-minute voltage average is stated; checking protection settings against the selected grid standard is only loosely supported (U</U> values depend on the country standard; Sungrow says to check that protection parameters are… -->