3-level NPC with transformer

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Hi guys...

I´m working in a 3-level NPC inverter conected to the grid. Before the grid i know that i have a transformer whit only this specifications.

6MW-8MVA-3.3kv primary side - 30kv secondary. the grid is connected in star conection

I need calculate the impedance the resistance and inductance. I can assume that the inductance is more or less 8-10% of the total impedance, but if i assume that and neglect the resistance the system doesn´t works. If i assume the resistance the other 90 % the system works perfect.

Do you know how to calculate the impedance resistance and inductance of the transformer with this values?

Thank u very much
 

The series inductance of a transformer depends on the layering of the windings, distance between layers, etc, etc. The parallel inductance depends on the core material, shape, turns, etc. You really can't just assume 90%.
 

i just calculated this values of the transformer from a datasheet using the rated impedance... but and i obtained for a 8MVA 3.3KV / 30 KV and copper losses equal to 48000W rated impedance 8.35% of Zbase values like Rt=0.0245 ohms and Lt=0.35 mH for the primary side.

I thought that it was the problem of my simulink simulation but not ... I don´t know why my simulation now does´t works... probably i had a mistake in the SPWM or in the parameters of simulink.

Thank u for your answer!!!!!!
 

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