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Error 159 | [Various software] | Invalid tap ratio specified


Relevant software:

PSS®E
PowerFactory


Emitted message:

Invalid TAPRATIO= specified given the transformers parameters

Description:​

This error occurs when a SET, TAPRATIO= Command specifies a tap ratio which is not possible given the configuration of the tap changer for this transformer, such as a tap ratio that is outside the allowable range for the transformer or is not a valid tap position for the tap changer.

Whilst some software packages support non-tap ratios for transformers, gridmo has standardised tap ratios to only be those which can exist on the specifeid transformer. This is to prevent benchmarking issues with the actual plant in the field.

Possible impact:​

  • The power systems simulation will not complete.
  • Connected Plot Nodes or similar will not plot any data.

Potential fixes:​

To resolve this error, you must provide a valid tap ratio.

  • Check Transformer Limits: Open your power system model file (e.g., .sav, .pfd) and inspect the parameters of the specified transformer. Note its minimum and maximum tap ratio limits and number of taps.
  • Correct the Command: Update the TAPRATIO= argument in your command to a value that is within the valid range for the transformer.
  • Review Logic: If the tap ratio is being calculated dynamically (e.g., via an Internode Variable), check the logic that determines the value to ensure it respects the transformer's operational limits.