704 / 2022-03-31 16:10:19

Analysis of discharge strategy after withstand voltage test of long-distance DC submarine cable

discharge strategy,HVDC submarine cable,withstand voltage test,ATP-EMTP,discharge simulation

The reception test of the HVDC submarine cable after completion is directly related to the project quality. While the residual voltage after the DC withstand voltage test has a certain degree of safety hazard for the cable itself and on-site personnel. To this end, this paper proposes a discharge strategy of switching series resistance in stages. By adjusting the resistance of the discharge circuit, the circuit voltage and current are limited, and the discharge efficiency of the cable body is greatly improved under the premise of ensuring the capacity of the equipment. Taking the first ±400kV Three Gorges flexible straight submarine cable transmission project in Asia as an example, the electrical parameters of the submarine cable are calculated according to the structure and material data of the DC-HYJQ41-F±400kV 1ⅹ1600+4×24B1 type submarine cable, and built in the ATP-EMTP software. Through the discharge simulation after the 580kV DC withstand voltage test of the submarine cable with a length of 108km and a capacitance of 20.088μF, the results show that: the voltage is firstly reduced through the voltage divider and the cable insulation resistance; Then, with the rated capacity of the discharge resistor as the limit, perform segmented switching discharge; when the residual voltage drops to 5kV, it is directly grounded for discharge. The discharge time that originally required 14 hours can be shortened to less than 60 minutes, and the simulation results are consistent with the actual data in the field.