NEED HELP TO DESIGN CONNECTION AT THE GRID SUBSTATION -TIERS AT THE ELECTRICAL DOMAIN

[RomuldKiobya]

Look attached document for more understanding. I have an incoming HV line Mufindi grid substation to the Mbeya Grid substation (Transmission tier). HV signal/connection travel to HV transformer (220KV/33KV) at the terminal of XFR-High. I created a Sub-transmission tier at the XFR-Low that ends with an MV circuit breaker at the Bus terminal. I made a Distribution tier at the MV Circuit breaker at the CB Line terminal.

My doubt about the Sub-transmission tier. And at what condition sub-transmission tier is used?

[JohnAlsup]

In this case you would not need the subtransmission tier.  Subtranmission is just like transmission, just a lower voltage, so subtransmission runs between stations, just like transmission.  I think you are trying to build a tier inside the substation for the equipment between the transformer and the breakers, is that correct?

[RomuldKiobya]

Yes, I need to create subnetwork controller and subnetwork, starting Low terminal  of HV transformer to CB bus of MV Circuit Breaker. So which tier I suppose select if not sub-transmission (contain high voltage devices and MV devices)  at sub network definition tool? 

[JohnAlsup]

Then you would just make the HV to MV transformer a subnetwork controller in the Distribution tier, call it Sub1 or some other name, and keep you the other subnetwork controllers at the circuit breakers in the distribution tier.