Bosnia: Regional electricity hub for traders, electricity network elements and its risks

22. January 2016. / SEE Energy News

Bosnia plays an essential regional electricity hub, between east and west blocks, importers and exporters. Electricity flow directions with its neighbors rely on Bosnia internal power flow network elements like 400 kV, 220 kV and 110 kV. TSO grid company announced serious grid modernization and investments in order to respond to future regional power flow demands.

For the direction of power flows from Bosnia and Herzegovina to Croatia, and evaluating all 400 kV, 220 kV and 110 kV network elements on the BiH side, the NTC value is set to 650 MW. It is not limited by any network element on the Bosnian side but due to maximum generation shift in Croatia.

For the same direction of power flows, evaluating all 400 kV, 220 kV and 110 kV network elements on the Croatian side, the NTC value is set to 380 MW. It is limited by OHL 110 kV, Žerjavinec – Jertovec, which gets overloaded as a consequence of an OHL 400 kV Žerjavinec – Tumbri outage. The thermal rating of the 110 kV critical line is set to 110 MVA. Monitoring the 400 kV and 220 kV network elements in Croatia only, the NTC value would rise to 491 MW and be limited by 400/110 kV transformers in the SS Žerjavinec (2×300 MVA). These transformers may be jeopardized when one of them is tripped off. Ignoring the internal Croatian network and evaluating the tie-lines only, the NTC would increase up to 569 MW due to maximum generation shift in Croatia.

Based on the lower NTC value between both sides, the final NTC value for the BiH to Croatia direction of power exchange is set to 380 MW. It is limited by the 110 kV Croatian internal line, Žerjavinec – Jertovec. The final NTC value, ignoring 110 kV networks, would be 491 MW, limited by 400/110 kV transformers in the Žerjavinec substation. If only Bosnian and Croatian tie-lines are evaluated without any network limitation for this value of power exchange across the border, the NTC value could be set to 569 MW.

For the direction of power flows from Croatia to Bosnia and Herzegovina, and evaluating all 400 kV, 220 kV and 110 kV network elements on the BiH side, the NTC value is set to 775 MW. It is limited by transformer 400/110 kV in the SS Ugljevik, which is jeopardized by an OHL 400 kV Tuzla – Ugljevik outage. For the same direction of power flow and evaluating tie-lines only (on Bosnian side), the NTC value is increased to 1584 MW, limited by the interconnection line 220 kV Zakučac – Mostar, which gets overloaded as a consequence of an OHL 400 kV Konjsko – Mostar outage.

For the direction of power flows from Croatia to BiH, evaluating all 400 kV, 220 kV and 110 kV network elements on the Croatian side, the NTC value is set to 1076 MW, limited by the 220 kV interconnection line Zakučac – Mostar.

Based on the lower NTC value between both sides, the final NTC value for the Croatia to BiH direction of power exchange is set to 775 MW if we evaluate internal networks. It is limited by the transformer 400/110 kV (300 MVA) in the SS Ugljevik. If we evaluate only tie-lines, the final NTC value is set to 1076 MW and is limited by interconnection line 220 kV Zakučac – Mostar (thermal rating 280 MVA at the model on Croatian side and 300 MVA on Bosnian side).

For the direction of power flows from Bosnia and Herzegovina to Montenegro, and evaluating all 400 kV, 220 kV and 110 kV network elements on the BiH side, the NTC value is set to 639 MW. It is limited by possible overloading of the OHL 110 kV Trebinje – Herceg Novi as a consequence of an OHL 400 kV Trebinje – Podgorica outage. Ignoring the 110 kV network in Bosnia, or complete internal Bosnian network, increases NTC up to 751 MW. It is limited by possible overloading of the interconnection line 220 kV Trebinje – Peručica as a consequence of an OHL 400 kV Trebinje – Podgorica outage.

For the same direction of power flows, but evaluating network elements on the Montenegrin side, the NTC values are almost the same with the same limiting elements.

Based on the lower NTC value between both sides, the final NTC value for the BiH to Montenegro direction of power exchange is set to 639 MW. It is limited by the OHL 110 kV Trebinje – Herceg Novi, with a thermal rating of 90 MVA on the Bosnian side (89,5 MVA on Montenegrin side). The NTC value could be set to 746 MW if only the Bosnian and Montenegrin 400 kV and 220 kV network or if only tie-lines are evaluated. It would be limited by the OHL 220 kV Trebinje – Peručica, with a thermal rating of 316 MVA on the Bosnian side at the model and 274,4 MVA on the Montenegrin side of the model.

For the direction of power flows from Montenegro to Bosnia and Herzegovina, evaluating all 400 kV, 220 kV and 110 kV network elements on the BiH side, the NTC value is set to 789 MW, limited by the 400/110 kV transformer in the SS Ugljevik, which is jeopardized by an OHL 400 kV Tuzla – Ugljevik outage. For the same direction of power flow and evaluating tie-lines on the Bosnian side only, the NTC value increases up to 1088 MW due to maximum generation shift in Montenegro and Bosnia and Herzegovina.

For the direction of power flows from Montenegro to BiH, no matter which network elements are evaluated on Montenegrin side of the border, the NTC value is set to 1088 MW, due to maximum generation shift at the model.

Based on the lower NTC value between both sides, the final NTC value for the Montenegro to BiH direction of power exchange is set to 789 MW if we evaluate internal networks. It is limited by the transformer 400/110 kV (300 MVA) in the SS Ugljevik, or 1088 MW if we only evaluate tie-lines and not limited by any network element.

For the direction of power flows from Bosnia and Herzegovina to Serbia, and evaluating all 400 kV, 220 kV and 110 kV network elements on the BiH side, the NTC value is set to 494 MW. It is limited by possible overloading of the OHL 110 kV Trebinje – Herceg Novi as a consequence of an OHL 400 kV Trebinje – Podgorica outage. Ignoring the 110 kV network in Bosnia increases NTC up to 731 MW. It is limited by possible overloading of the interconnection line 220 kV Trebinje – Peručica as a consequence of an OHL 400 kV Trebinje – Podgorica outage.

For the same direction of power flows and evaluating all 400 kV, 220 kV and 110 kV network elements on the Serbian side, the NTC value is set to 0 MW. This means that additional power exchanges are not possible due to limitations in the 220/110 kV transformers in the SS Sremska Mitrovica (initially highly loaded at the base case model). By ignoring the internal Serbian network and evaluating tie-lines only, the NTC would increase up to 1368 MW due to maximum generation shift in BiH.

Based on the lowest NTC value between both sides, the final NTC value for the BiH to Serbia direction of power exchange is set to 0 MW and is limited by transformers (2×150 MVA) in Sremska Mitrovica because of their high loading in the base case. The NTC value could be set to 731 MW if only the Bosnian and Serbian tie-lines are evaluated, limited by the OHL 220 kV Trebinje – Peručica with thermal rating defined to 316 MVA on Bosnian side at the model.

For the direction of power flows from Serbia to Bosnia and Herzegovina, and evaluating all 400 kV, 220 kV and 110 kV network elements on BiH side, the NTC value is set to 473 MW. It is limited by the 400/110 kV transformer in the SS Ugljevik that is jeopardized by an OHL 400 kV Tuzla – Ugljevik outage. For the same direction of power flow and evaluating tie-lines on the Bosnian side only, the NTC value is increased to 1597 MW. It is limited by the 220 kV interconnection line, Višegrad – Vardište, that gets overloaded as a consequence of an OHL 400 kV Tuzla – Ugljevik outage.

For the direction of power flows from Serbia to BiH, evaluating all 400 kV, 220 kV and 110 kV network elements on the Serbian side, the NTC value is set to 791 MW. It is limited by the OHL 110 kV Đerdap – Negotin, which is jeopardized if the OHL 110 kV Đerdap – Prahovo goes out of operation. This limitation is caused by the increase of the HPP Đerdap production while applying the generation shift key. Ignoring the 110 kV network in Serbia, and also the complete Serbian internal network, the NTC value could be increased up to 1278 MW with limitations in the OHL 220 kV Bajina Bašta – Pljevlja (thermal rating 274,4 MVA on Montenegrin side and 388 MVA on Serbian side at the model) that may be overloaded following an OHL 220 kV Bajina Bašta – Požega outage.

Based on the lower NTC between both sides, the final NTC value for the Serbia to BiH direction of power exchange is set to 473 MW if we evaluate internal networks. It is limited by the transformer 400/110 kV (300 MVA) in the SS Ugljevik. If we evaluate only tie-lines, the final NTC value is 1278 MW and is limited by the interconnection line 220 kV Bajina Bašta – Pljevlja, transmits serbia-energy.eu

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