Voltage measurement problem with isolated system ?

Hi everyone.

I have some problems with this simulation. I try to explain: my load is an electric arc furnace and each "controlled voltage source" is the arc voltage. There is a non-grounded star point.

Externally, I have to measure the three phase-to-ground voltages of each arc for control system. (those three voltage measurement blocks) referred to ground.

When I start the simulation I have this problem:

"The Voltage Measurement block 'Voltage Measurement2' is connected between two isolated networks. For a valid measurement, the positive and negative terminals of the block must be connected to electrical nodes that are part of the same electrical circuit. Also check if the ground reference node is defined for that circuit."

I could solve the problem putting a grounded star point load, but it's not the reality. Furthermore, I can't change the secondary winding of MT/BT transformer to Yg because it is delta in reality.

Some ideas? What can I do ?

Thanks.

[yu]

It is now the problem should be how to solve, thank you

[Muhd Haziq]

how to solve this ?

[Luke McDevitt]

I still have this same problem

Answer 1

[Saad Ullah Khan]

Add a large resistance in parallel for each phase.

[Asi angel]

Can you tell me why?!! @Saad Ullah Khan

Answer 2

[Joel Van Sickel]

You would never measure the voltage from a floating source to ground, so there is something wrong in your approach. You can either measure the line to line voltage, and convert it to phase voltage, or ground the system.