Why is there DC offset present and how can this be removed?

I have a simple system as shown below:

consisting of a 11kV three phase voltage source with parameters:

Phase shift: 0

Frequency: 50Hz

Source impedance: X/R ratio of 3

SCL: 10e6

This is simply connected to a 11kv/400V transformer with an open circuit on the other side. The transformer has values:

Rated Power = 1.2e6

Frequency = 50Hz

Winding 1 = Wye with N port

Winding 2 = Delta 1 o'clock

The transformer impedances are:

This is a very simple circuit but I'm getting very detrimental DC offset in the currents which is producing a 50Hz component in power:

Shown above are the three phase currents. Why is there so much DC offset? and how can this issue be solved?

Answer 1

[Joel Van Sickel]

The issue is that the initial conditions are unbalanced and as it's an open circuit with very little current flowing, it'll take a very long time for the system to reach it's steady state balanced operation. You can set the system to start in steady state in the solver configuration block options to fix this problem.