As per my understanding, you are trying to simulate a three phase transformer and you want to model its zero sequence inductance that plays significant role during transient conditions.
For this purpose, you can use “Three-Phase Transformer Inductance Matrix Type (Three Windings)” block from “Simscape / Electrical / Specialized Power Systems / Power Grid Elements” library as shown in the below figure.
It is a three-phase transformer with a three-limb core and three windings per phase, as shown in the below figure:
Please refer to the below documentation for more information regarding “Three-Phase Transformer Inductance Matrix Type (Three Windings)” block.
Open the “block parameters” and set the core type to “Three limb or 5 limb core”.
You will then be prompted to enter the transformer's zero-sequence impedances, as illustrated in the diagram below.
“X12”, “X23”, and “X13” are the The zero-sequence short-circuit reactances in PU (Per-Unit). “Xij” is the reactance measured from winding “I” when winding “j” is short-circuited. The defaulted values are “[0.1, 0.2, 0.3]”
Now addressing your second question:
“Does anyone have tabulated values for the zero inductance of different power transformers in the distribution network?”
The zero-sequence impedance of a three-phase transformer depends on its connection type and can vary between different manufacturers. Here’s an example table that lists hypothetical values for zero-sequence inductance for different transformer configurations
Additionally, please refer to the following test report of power transformer by ABB (page 31):
It states that:
“The zero-sequence impedance is usually given as a percentage of the rated
phase impedance. When the transformer has a three-limb core and no delta-
connecter windings, the zero-sequence impedance is about 30...60 %. When
the transformer has a delta-connected winding, the zero-sequence impedance
is 0.8...1.0 times the corresponding short-circuit impedance”
Please refer to the above test report to have a clear understanding of how the zero sequence impedances are measured.
I hope this helps !
