Why do I receive the error 'Invalid setting in block for parameter 'InputValue'' when I use negative values for Saturation Characteristics in the Three-Phase Transformer block in SimPowerSystems 4.0.1 (R14SP2)?

When I use negative values for my saturation characteristics in the Three-Phase Transformer block I receive the following error when I update my model:

 Invalid setting in block 'power_transfo3ph2_GS/450 MVA 500-230 kV Three-Phase Transformer/model/transformer1/Look-Up Table' for parameter 'InputValues'

Physically it should be possible to specify negative values since there should be a mirror of the values in the opposite direction.

Answer 1

[MathWorks Support Team]

This bug has been fixed in Release 2007a (R2007a). For previous product releases, read below for any possible workarounds:

This is the intended behavior in SimPowerSystems 4.0.1 (R14SP2) when specifying Saturation Characteristics within the Three-Phase Transformer block. When specifying the Saturation Characteristics, one only needs to enter the positive part of the flux-current curve. SimPowerSystems assumes that the negative part is the mirror of the positive part.

Using an implicit negative curve prevents the user from entering a non-symmetrical curve by mistake.