To change the topology of the transformer (Y or Delta) the following is the syntax shown in the examples.
PowerSystems.AC3ph.Transformers.TrafoStray trafo(redeclare PowerSystems.AC3ph.Ports.Topology.Delta top_n "Y",redeclare PowerSystems.AC3ph.Ports.Topology.Delta top_p "Delta") annotation(Placement(visible = true, transformation(origin = {-12, -2}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));

The follow error message is received
[3] 22:34:03 Translation Error
Internal error pre-optimization module clockPartitioning failed.

[4] 22:34:03 Symbolic Error
Too few equations, under-determined system. The model has 100 equation(s) and 114 variable(s).

It seems that the values of parameters on top_n and top_v are missing  (v_cond and i_cond).