Modeling Generator 17MW and is giving 4MW

[ppinuelas]

Hey guys, I am new to the forum so this is my first post with a question.

I am working in an industrial project where we are designing the substation, we are receiving from the utility company 115kV and we are stepping down to 13.8kV with a 18/24/30MVA transformer to a medium voltage switchgear. In this project we are going to have a 17MW, 13.8kV Generator that is going to be connected to the switchgear on the substation and synchronized with the utility company.

I am modeling the system in SKM and the problem is that when I connect directly the generator to the switchgear and i run the calcs for load flow the power that the generator is giving is of 40MW and the utility company with consuming kW, but, when I connect a 1 to 1, or 13.8kV to 13.8kV transformer between the generator and the switchgear, the generator gives normal power, about 12MW which makes more sense.

Does anybody know why this happens?

Thanks

 

[dpc]

Welcome to Eng-Tips.

You will have to define the desired kW output of the generator to the software. In the real world, the contribution of the local machine will be controlled by the fuel into the prime mover. You can't model it as swing source and expect the program to know what you want to load it to.

The utility should be a swing source and the generator should be modeled as a constant voltage or constant kW source with a max output.

I can't remember exactly what this looks like in PowerTools, but there should be similar-sounding options available.

Dave