Test Results of the Full-Scale HTS Transmission Cable Line (2.4 Km) for the St. Petersburg Project

Complex tests of all components of the HTS DC cable line were carried out within the framework of the National project for the implementation of a superconducting DC cable line with a capacity of 50 MW, 20 kV in the power system of St. Petersburg. The tests were carried out at the Research and Development Center of the Federal Grid Company of Unified Energy System, Moscow. The experimental stand consisted of six lengths of cables with five couplings and two current leads, reverse cryostat (no cable inside), dual-circuit cryogenic system with a rated power of 12 kW at 77 K, the rectifier - inverter device and the automatic process control system. In accordance with the approved project for laying the HTS line in Saint Petersburg, the total cable length was 2400 meters. The cryogenic circuit total length exceeds 2700 meters and includes cable in cryostat, reverse cryostat (300 meters), thermal load simulator and measuring equipment. The report describes the scheme of a two-circuit cryogenic unit with a closed cycle and analyzes possible emergency modes of the system. The report presents the results of vacuum and cryogenic tests carried out over several months under power load. The cable protection system and its test results are described. The temperature of liquid nitrogen and its flow rate varied widely during the test. The electrical and hydraulic characteristics of the HTS cable line and reverse cryostat were determined. The connection scheme of substation “Tsentralnaya 330 kV” and substation “RP 9 220 kV” will be presented. The HTS cable line connection to the St. Petersburg network is scheduled for the end of 2021.