Transforming existing 220 kV double circuit line into 400 kV single circuit line in Romania

The transmission system operators TRANSELECTRICA (TEL-Romania) and EMS (Serbia) have decided to increase the interconnection capacity on the common border by building a new 400 kV transmission line.The aim of the new 400 kV interconnection line is to serve both system operators in achieving the common goal-a more reliable power supply to the customers at a lower electricity price. In the same context, TEL has decided to upgrade the transmission line corridor in the Western part of Romania from 220 kV to 400 kV voltage level, in order to facilitate the evacuation of exceeding power from Portile de Fier area (including hydro power plants Portile de Fier, Portile de Fier 2, thermal power plant Halanga and future wind power park planned in the same area). With these goals, the authors have been prepared a report regarding the feasibility of the project. The objectives of the report have been: (a) Compare from technically and economically point of view two candidate interconnection lines with the Serbian system. (b) Identify and recommend an optimal configuration for upgrading the transmission corridor between Arad and Portile de Fier, taking into account the future 400 kV interconnection with the Serbian system. The paper presents only the most important results obtained regarding the system study and the optimal solution for corridor transforming.