System Control Model

System operation model is based on the accepted structure “1+4” – one main control center and four secondary level network control centers.

Operation of the Croatian power system is hierarchically organized and is carried out from three levels:

  • National Dispatch Center (NDC), located in Zagreb, is at the highest level,
  • four network control areas are at the second level, located in Rijeka, Split and Osijek and one in Zagreb that is planned to be built soon,
  • the third level comprises power plants, substations and chain and basin hydro plants control centers. 
NDC is the main control centre controlling the power system as a whole  centre of  the Croatian Control Area in ENTSO-E. It is responsible for system operation planning and real-time system operation. NDC is authorized to coordinate the activities with system operators of neighboring control areas, coordinators of control blocks and ENTSO-E coordination centers.

In their respective transmission areas the network centers perform the following functions:
  • monitor and control the 400 and 220 kV network and 110 network of system importance in their respective transmission areas according to NDC  instructions,
  • independently monitor and control the 110 kV network that is not of system importance in their respective transmission areas,
  • other duties relating to system operation as assigned to them by NDC.