The Croatian TSO (HOPS) shares national borders with Serbia, Hungary, Bosnia and Herzegovina and Slovenia. Croatia is part of SCB block together with Slovenia and Bosnia. Croatia is an importer of electricity and located next to SMM block Serbia Montenegro Macedonia.
The indicative annual NTC value for the Croatian/Bosnian border was set to 400 MW for both directions over the considered time frame. The indicative annual NTC value for the Croatian/Serbian border was set to 100 MW in the observed time frame for the Croatia to Serbia direction, and 200 MW in 2012, 150 MW in 2013 and 100 MW in 2014 for the Serbia to Croatia direction.
The indicative annual NTC value for the Croatian/Hungarian border was set to 600 MW for direction from the Croatia to Hungary and 700 MW for the opposite direction, over the considered time frame.
Month-ahead NTC values for January 2015 were set to:
Croatia/BiH border 700 MW (for both directions)
Croatia/Hungary border 700 MW – 1200 MW (for HR to HU direction) and 600 MW – 1000 MW (for HU to HR direction)
Croatia/Serbia border 600 MW (for both directions)
Croatia/Slovenia border 1200 MW (for HR to SI direction) and 950 MW (for SI to HR direction)
Day-ahead NTC values in January 2014 were set to:
Croatia/BiH border700 MW (for both directions)
Croatia/Hungary border1000 MW (for HR to HU direction) and 1200 MW (for HU to HR direction) Croatia/Serbia border600 MW (for both directions)
Croatia/Slovenia border1350 MW (for HR to SI direction) and 1150 MW (for SI to HR direction)
For the direction of power flows from Croatia to Hungary, the NTC value is set to 789 MW without any network limitations, 400 kV, 220 kV and 110 kV evaluating voltage levels, but due to maximum generation shift in Croatia.
For the direction of power flows from Hungary to Croatia, evaluating all 400 kV, 220 kV and 110 kV network elements on the Croatian side, limitations appear when NTC values are set to 1811 MW, concerning the 110 kV line Žerjavinec – Jertovac (thermal capacity 110 MVA at the model), jeopardized by an OHL 400 kV Tumbri – Žerjavinec outage. Ignoring the 110 kV network in Croatia, the NTC value could be increased above 2000 MW, limited by 400/110 kV transformers in the SS Ernestinovo (2×300 MVA).
Obviously, there are possibilities for significant power exchanges between these two countries in present conditions.
For the direction of power flows from Croatia to Slovenia, evaluating all 400 kV, 220 kV and 110 kV network elements, the NTC value would be 1009 MW from the Croatian side and 1259 MW from the Slovenian side. The NTC value is limited because of the OHL 110 kV Crikvenica – Krk, which is jeopardized by an OHL 110 kV Melina – Vinodol – Crikvenica outage. This contingency provides a lower NTC value, evaluationg both sides of the border. The critical line has a thermal rating of 70 MVA at the model and consists of submarine cable and overhead line sections. The submarine cable has low cross-section that reduces thermal capacity of the line. The NTC value would be limited by the Slovenian side by possible overloading of the OHL 110 kV I. BIstrica – Matulji as a consequence of the line 220 kV Pehlin – Divača outage. The critical line is a cross-border line between Slovenia (I. Bistrica) and Croatia (Matulji) with low thermal capacity (83,8 MVA on Slovenian side and 89 MVA on Croatian side at themodel, constructed long ago).
Monitoring 400 kV and 220 kV network elements of the Croatian and Slovenian transmission system and ignoring the 110 kV networks, the NTC value would be limited by the 220 kV tie-line Pehlin – Divača, with a thermal capacity of 360 MVA on the Croatian side and 365,8 MVA on the Slovenian side at the model. Critical contingences in Croatia and Slovenia are different. The OHL 220 kV Pehlin – Divača is jeopardized by outages of the tie-line 400 kV Melina (HR) – Divača (SI) when evaluating the Croatian side, and outages of the tie-line Divača (SI) – Redipuglia (I) when evaluating the Slovenian side. The NTC values would be defined up to 1471 MW on the Croatian side and 1402 MW on the Slovenian side, so the final NTC value of 1402 has been defined as the lower one.
For the opposite direction of power exchanges (Slovenia to Croatia), the NTC value is limited by the OHL 110 kV HPP Formin – Nedeljanec, which gets overloaded as a consequence of an OHL 110 kV Žerjavinec – Jertovec outage on the Croatian side (NTC is 344 MW) or the OHL 400 kV NPP Krško – Maribor on the Slovenian side (NTC is 594 MW). Ignoring the 110 kV network and monitoring 400 kV and 220 kV network elements, the NTC values would be increased to 487 MW on the Croatian side and 631 MW on the Slovenian side, limited by the 400/110 kV transformers in the SS Tumbri (3×300 MVA, one transformer is permanently out of operation but may be putted in operation) in Croatia and 220/110 kV SS Divača in Slovenia (2×143,5 MVA at the model). Evaluating the tie-lines of both countries only, the NTC values would be increased up to 880 MW due to maximum generation shift in Croatia and without any network limitations, transmits Serbia-energy.eu
