Error in Ymatrix when building model from RAW file

NREL-Sienna / PowerSystems.jl

Data structures in Julia to enable power systems analysis. Part of the Scalable Integrated Infrastructure Planning Initiative at the National Renewable Energy Lab.

https://nrel-sienna.github.io/PowerSystems.jl/stable/

BSD 3-Clause "New" or "Revised" License

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Error in Ymatrix when building model from RAW file #853

Closed tavovalmo closed 2 years ago

tavovalmo commented 2 years ago

Hi, I have a 4-bus test system with an off-nominal tap position transformer. The resulting Ymatrix is wrong. This occurs when I use a raw (PSSE) file. However, when I build the same system with Matpower, I have no problems. Please see attached.
Ybus_wrong TVC_SystemMATPOWER.csv TVC_SystemRAWPSSE.csv

jd-lara commented 2 years ago

It looks like the data has a problem, the r and x values for the tap transformer "BUS4-BUS3-i_4" are 0.0. I am not sure how PSS/e or Matpower handles these cases internally but we don't support it.

I added some protection to detect these cases just in case in PR #854

tavovalmo commented 2 years ago

This transformer has a reactance value different from zero in the sav file. Something is wrong when PSSE converts from sav to raw file.

jd-lara commented 2 years ago

@tavovalmo1983 The issue is that in the data set the base voltage of the transformer is set to 0.0 and the parser does a per-unit transform of the transformer from its base to the system base. Since the base voltage is set at 0.0, the transformation results in a base impedance of 0.0. I opened another PR to catch this issue.