Italy-Austria GIL in the new planned railway galleries Fortezza-Innsbruck under Brenner Pass

The paper deals with the possibility of installing a double-circuit Gas Insulated transmission Line (GIL) in the pilot tunnel of the new planned railway galleries Fortezza-Innsbruck. The high GIL power ratings with very low power losses would allow a strong and highly efficient energy exchange particularly useful for the future European Market and could represent a new fundamental step in reconstructing the European interconnection network. Two separate railway tunnels (Φ ≈ 9,6 m) will run under the Brenner Pass from Fortezza (Italy) to Innsbruck (Austria) but will be preceded by the construction of a continuous pilot tunnel (Φ ≈ 4,3 m) useful for work logistics and chiefly for detection of the rock stratigraphy. Once the whole work will be over, the pilot tunnel will be used as a service gallery (drainage of water) where a double-circuit GIL can be efficiently installed. The paper gives the main characteristics of planned galleries, several details on the transmission line and its performance, the electro-magnetic field impact considering the proximity effects and the earthing arrangement in order to zero the touch-voltages in case of phase-to-enclosure short-circuit. The chief features of GIL solution are the lowest transmission power losses and the absence of shunt reactive compensation for this line length (appr. 65 km) but mostly the safety of personnel in case of shortcircuit and the possibility of usual re-closure cycles for operation continuity. This paper gives an overview of other analysis: GIL no-load regime, electromagnetic interferences between railway and GIL system, pilot tunnel ventilation and GIL thermal regime. In order to achieve satisfying power flows, the new link requires both Italian/Austrian regional grids (380 kV÷110 kV) to be restructured and rationalised. This research is supported by European Community in the framework of TENENERGY programme for analysing both, technical and environmental issues of integrating 380 kV Gas Insulated transmission Line and Rail Transport in tunnel between Italy and Austria entitled "Studies for a new 380 kV transmission line between Italy and Austria through the Brenner pass: Integration of Electricity and Rail Transport in Tunnel". The project leader is TERNA (Italian TSO) whereas the associated beneficiaries are the University of Padova and TIWAG-Netz AG (Tyrol TSO) with support of Graz University of Technology.