Experience of HVDC Interconnection Italy-France called “Piemonte-Savoie” Problems connected with EMF – ELF Study of interferences with other services in tunnel

This paper presents the main results of the studies carried out for the project of High voltage Direct Current (HVDC) Interconnection between Italy and France, called “Piemonte-Savoie” about electromagnetic interferences with other services.
The project has been jointly performed by TERNA and RTE and the studies have been made with the support of the Italian Electrotechnical Experimental Centre, CESI.
The new interconnection line is an HVDC underground link between the existing Electrical Substation of Piossasco (TO) [Italy] and the existing Electrical Substation of Grand-Ile [France], crossing the National border inside the future Frejus Safety Tunnel. This cable route has been chosen as existing motorway facilities could, on one hand, allow the possible construction of new High Voltage (HV) transmission links within a shorter time horizon, and on the other hand, get better acceptance than conventional routes. Thus the possible integration of HV transmission lines with motorways Infrastructures is a key feature for this project.
When dealing with multipurpose structures, like the future Frejus Security Tunnel, the Transmission System Operators (TSO) have been asked to provide information concerning the compatibility of the link with other installed plants and equipments, including possible electromagnetic interferences.
The paper presents the main characteristics of the interconnection “Italy-France” and its peculiarity, including the laying inside the future Frejus Security Tunnel and the choice of Voltage Source Converters (VSC) for converter stations technology. Subsequently, the main results of the studies about possible electromagnetic interferences from the DC link on other services and transmission systems inside the Security Tunnel are described, in terms of induced voltages caused by harmonics and fault transients of the link.
At last, the paper shortly presents the European framework on regulation on EMF generated by DC lines and the experience of the TSO, in this project, concerning the way to answer to the requests from Public Authorities. ​​