Direction of power flow for 132/33kV, 80/100MVA transformer

[krisys]

One of our hydrocarbon processing facility which has a total power generation capacity of about 180MW (6 nos. x 30MW GTGs) and presently operating in island mode. In order to improve the power system reliability, now it will be connected to utility grid using two (2) nos. of 220/132 kV, 80/100 MVA interconnecting transformers. Originally during the engineering, only the power import was envisaged. Now the requirement of export of power is also required. While procuring the transformer, the direction of power was not specified in the purchasing document.

I presume, that the direction of power flow is from HV to LV unless it is specified otherwise.
At the back of my mind, it says, these kind of transformers shall be by default suitable for bi-directional power flow. Any thought on this?

 

[Power0020]

Any transformer can be used for bi-directional power flow, however, the protection setting should be checked (inrush current, coordination, distance (if used)).

Directional relays may be employed "tho not common" which may need to be blocked/reset.

If the Auto-transformer has NER, it is a must to recheck the voltages in case of ph-ground faults.

Another point is if the transformer is delta connected and will be islanded, a voltage with no ground reference may appear at this case.

 

[ScottyUK]

Check your tapchanger range to ensure that it will allow adequate control of reactive power flow.

 

[prc]

Some of the on-load tap-changers are suitable for power flow in one direction only.This may be checked.