Specifics of integration of wind power plants into the Croatian transmission network

► Modelling Croatian transmission system and determining relevant scenarios for large-scale wind power integration. ► Investigating the potential for reversible hydro power plants as storage in large wind power integration. ► Analyzing current and proposing less discriminatory connection cost policy. Increasing number and capacity of wind turbines have overgrown connection to the distribution network. Considerable wind power plant installed capacity makes their connection to the transmission network a common practice today. However, large scale wind power integration requires increase in transmission network capacity. The problem with transmission network capacity investments is that they will be fully utilized only on rare occasions. This makes the investments in power lines reinforcement economically questionable. The transmission network capacity problems get even worse when several large wind power plants with simultaneous peaks in production are connected to the transmission network in the same node. The objective of this paper is to provide an insight in the issues of large-scale wind power plant integration into the transmission grid in Croatia. An accurate and detailed model for assessing power flows and voltage levels has been developed as a result of multiple projects involving wind power plant connections to the Croatian transmission network. Problems of large-scale wind power plant integration into the Croatian transmission network are addressed and solutions acceptable for both the investors and the Transmission System Operator are proposed.