Reliability Assessment of Southern Croatian Transmission Network

This paper presents the reliability assessment of the southern part of Croatian transmission network in the region around the Dubrovnik city. Reliability of the southern part is very low in present time, and several hard power supply interruptions have appeared in years 2009 and 2010. There are plans of installing a new GIS (Gas Isolated Switchgear) substation 220/110 kV Plat in that region. Reliability assessment was performed, and reliability indices were computed before and after construction of a new GIS substation 220/110 kV Plat. The reliability is analyzed using DIgSILENT Power Factory 14.0 software. Input data were obtained from annual reports of HEP TSO (Croatian Electric Utility Transmission System Operator) and statistic analysis of data was performed first. Since there are no statistical data for new GIS substations, input data for them were taken from the relevant literature. In reliability assessment Markov state space model of primary substation components such as busbars, transformers, breakers and disconectors was used. Load is modeled at the output substation busbars with maximum active and reactive power. The state enumeration method is used for reliability analysis. Results are showing high level of improving reliability after a new GIS 220/110 kV substation is put in the function.