Albania: Electricity flow directions and regional overloading

20. January 2016. / SEE Energy News

Albania electricity imports directions from Montenegro, Greece and Serbia are largely influenced by the overloaded interconnections in SEE region. In the same time Albania-Kosovo direction shows the importance for the importer which is largely dependant on the electricity imports.

Albania electricity import dependency is significant. Albania is synchronously operated with the UCTE/Continental European (CE) system since 1986.

For the direction of power flows from Albania to Greece, and evaluating all 400 kV, 220 kV and 110 kV network elements on the Albanian side, the NTC value is set to 360 MW. It is limited by the 220/110 kV transformers in Tirana (rating of 2×120 MVA at the model), which are jeopardized if one of them goes out of operation. For the same direction of power flow, but evaluating tie-lines on the Albanian side only, the NTC value rises to 440 MW and is limited by the maximum generation shift in Albania at the model.

For the direction of power flows from Greece to Albania, and evaluating all 400 kV, 220 kV and 110 kV network elements on Albanian side, the NTC value is set to 340 MW. It is limited by the OHL 110 kV Tirana – Selite, which gets overloaded as a consequence of an OHL 220 kV Tirana – Rrashbull outage. For the same direction of power flow and monitoring the Albanian 400 kV and 220 kV network elements only, the NTC value would be set up to 427 MW. It is limited by the 400/220/30 kV transformers in the SS Elbasan (rating of 2×300 MVA at the model), which could be overloaded if one of them trips off. Repeating a calculation but evaluating tie-lines on the Albanian side only, the NTC value is increased to 683 MW. It is limited by the OHL 220 kV Fierza – Prizren (thermal rating 325,4 MVA on Albanian side at the model), which gets overloaded if OHL 400 kV Zemlak – Kardia goes out of operation.

For the direction of power flows from Albania to Kosovo, and evaluating all 400 kV, 220 kV and 110 kV network elements on Albanian side, the NTC value would be set to 641 MW, limited by the 220/110 kV transformers in the SS Tirana, which get overloaded if one of them goes out of operation. For the same direction of power flow and evaluating 400 kV and 220 kV networks or tie-lines on Albanian side only, the NTC value would be increased up to 671 MW without any critical network element due to maximum generation shift in Albanian at the model.

For the direction of power flows from Albania to Kosovo, and evaluating all 400 kV, 220 kV and 110 kV network elements on the Kosovo and Serbia side, the NTC value is set to 178 MW. It is limited by the 220/110 kV transformers in the SS Sremska Mitrovica, which get overloaded if one of them goes out of operation. The PSS/E model includes area “RS,” which comprises of Serbia and Kosovo, so generation shift in these countries was performed using generators, not only in Kosovo, but in Serbia as well. Limitations in the 220/110 kV transformation in the SS Sremska Mitrovica are not realistic because critical transformers are situated far away from the evaluated border and they are highly loaded in the base case (99 % Sr). Due to a decrease of generation in Kosovo and Serbia (RS area), there will be an increase of power exchange between the Serbian/Croatian and Bosnian border, with a slight increase of the 220/110 kV transformers in the SS S. Mitrovica loading. Ignoring this loading violation, we approach a more realistic possible NTC value between Albania and Kosovo for the direction of exchange from Kosovo and Serbia to Albania but evaluating the network of Kosovo and Serbia only, in the amount of 671 MW. It is limited by maximum generation shift in Albania and without any limitations in the networks of Kosovo and Serbia.

Based on the lower NTC value between both sides, the final NTC value for the Albania to Kosovo direction of power exchange is set to 178 MW if we evaluate the internal transmission systems of Albania, Kosovo and Serbia. It is limited by the high loading of the 220/110 kV transformers in the SS S. Mitrovica (rating 2×150 MVA at the model). Ignoring this non-realistic limitation, the NTC value increases to 641 MW, limited by the 220/110 kV transformers in the SS Tirana, and up to 671 MW evaluating tie-lines only, due to maximum generation shift in Albania at the model. Excluding Serbia from the NTC calculations, meaning that only generation shift in Kosovo is performed (with constant generation in Serbia), the NTC value for the Albania/Kosovo border and Albania to Kosovo direction of power exchange will be set to 127 MW. It is not limited by any network element but limited due to maximum generation shift in Kosovo.

For the direction of power flows from Albania to Montenegro, evaluating all 400 kV, 220 kV and 110 kV network elements on Albanian side, the NTC value is set to 386 MW. It is limited by the 220 kV internal line,

V.Dejes – Koman, which gets overloaded as a consequence of an OHL 220 kV Tirana – Kolac outage. For the same direction of power flow and evaluating only tie-lines on the Albanian side, the NTC value stays the same due to maximum generation shift in Albania at the model.

For the direction of power flows from Albania to Montenegro, and evaluating all 400 kV, 220 kV and 110 kV network elements on Montenegrin side, the NTC value is set to 383 MW, limited by the 220 kV interconnection line, Podgorica – V.Dejes, that gets overloaded as a consequence of an OHL 400 kV Podgorica – Tirana outage.

Based on the lower NTC between both sides, the final NTC value for the Albania to Montenegro direction of power exchange is set to 383 MW and is limited by the 220 kV interconnection line, Podgorica – Vau Dejes, thermal rating (defined as 274 MVA on Montenegrin side and 278 MVA on Albanian side at the model).

For the direction of power flows from Montenegro to Albania, and evaluating all 400 kV, 220 kV and 110 kV network elements on the Albanian side, the NTC value is set to 291 MW. It is limited by the 400/220/30 kV transformers in the SS Elbassan, which get overloaded as a consequence of an OHL 220 kV Podgorica – Vau Dejes outage. For the same direction of power flow and evaluating tie-lines on the Albanian side only, the NTC value is increased to 430 MW. It is limited by the 220 kV interconnection line, Podgorica – V.Dejes, which gets overloaded as a consequence of a OHL 400 kV Podgorica – Tirana outage.

For the direction of power flows from Montenegro to Albania, and evaluating all 400 kV, 220 kV and 110 kV network elements on Montenegrin side, the NTC value is set to 439 MW, limited by the 220 kV interconnection line Podgorica – V.Dejes.

Based on the lower NTC value between both sides, the final NTC value for the Montenegro to Albania direction of power exchange is set to 291 MW if we evaluate the internal Albanian network, and is limited by the number and rating of transformers in Elbassan (defined as 2×300 MVA). The final NTC value is 430 MW if we evaluate tie-lines only and is limited by the 220 kV interconnection line, Podgorica – V.Dejes, transmits Serbia-energy.eu

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