Engineering and operating the 230kV, 50Hz interconnector between Malta and Italy

In March 2015, the 230kV, 50Hz, 200MW interconnection between the islands of Malta and Sicily (IT) was commissioned and put into operation. The interconnector consists of a 230kV air-insulated substation (AIS) extension in Sicily, a 19km single-core XLPE land cable circuit, and a 99km three-phase XLPE submarine cable directly terminated to a 230kV gas-insulated substation (GIS) in Maghtab, Malta. Shunt reactors are installed on either side for compensation of the reactive power generated by the long cable. High voltage (HV) 50Hz technology was chosen in favour of HVDC because of its simplicity, reliability, cost-effectiveness and the possibility of overloading in emergencies. Aspects of interest shown in the paper are considerations taken in the design of the system and some records of the performance since commissioning. A detailed analysis of the losses in the submarine cable and its temperature performance as installed is provided in the second part of the paper. The paper is intended to be of interest to operators considering the application of HV 50Hz connections using XLPE cables especially for long-distance offshore windfarms and island interconnections.