To clarify the influence of different metallic screen types on the current rating capacity of HVDC cables

and to compare the accuracy of calculation results of thermal analysis and finite element simulation

we selected ±525 kV XLPE insulated cables with copper conductor cross-section of 3 000 mm

2

as examples to perform the experiments. The current rating capacity of HVDC cable with copper wires and corrugated aluminium sheath were calculated based on thermal analysis and finite element simulation respectively

then the results were verified by DC current

loading tests. The calculation results show that the current rating capacity of HVDC cable with copper wires is greater than that with corrugated aluminium sheath under the same condition. But the results based on two calculation methods above are both smaller than those of loading tests

and also obvious deviations exist. Based on thermal analysis

the current rating capacity of ±525 kV cable with copper wires is 2 842 A under 28 ℃ in air

which decreases by a 7.5% compared to the result of finite element simulation and decreases by 15.8% compared to the result of DC current loading tests

respectively. Under the same condition

the current rating capacity of ±525 k V cable with corrugated aluminium sheath is 2 836 A based on thermal analysis

which decreases by 5.3% compared to the result of finite element simulation and decreases by 8.6% compared to the result of DC current loading test

respectively. The reason is that

in the thermal analysis

only the influence of thermal resistance in the process of cable heat conduction is taken into consideration

but the increase of heat radiation of external air convection to current rating capacity can not be calculated

and also the effect of air on heat transfer inside the cable structure is not taken into consideration. Due to the ability to recognize thermal radiation effects in addition to heat conduction

the calculation results based on finite element simulation are more close to test results. However

the finite element simulation model can not represent the air-gap and corrugated aluminium sheath of cable accurately

and the heat dissipation of cable caused by airflow in current loading tests can not be simulated accurately by finite element simulation.