125 / 2022-03-13 21:52:35

Optimization of DC electric field of AC XLPE cable joint in DC operation

XLPE Cable,cable joint,DC operation,electric field distribution,Optimization

Purpose/Aim

With the development of new energy, new materials and power electronics technology, DC distribution technology has attracted more and more attention around the world. However, the cost of new DC distribution grid is very high. If the AC distribution cable can be converted to DC operation, it is of great significance for the realization of DC distribution grid. The cable accessories are the weakness of the XLPE cable system, and the DC electric field distribution of AC XLPE cable accessories is very important for the AC cable system in DC operation. However, there are few studies on AC XLPE cable accessories under DC voltage. In this paper, the steady-state DC electric field of the 10 kV AC XLPE cable joint is optimized.

Experimental/Modeling methods

The thermo-electric coupling simulation model of 10 kV AC XLPE cable joint was built in the finite element simulation software. In the thermal field simulation of cable joint, the temperatures of cable conductor and the outer sheath were fixed to realize the various insulation temperature differences. In the steady-state DC electric field simulation, the DC voltage was applied to the cable conductor, and the outer sheath  and the stress cone of cable joint were grounded.

Results/discussion

The thickness of the high-voltage shielding tube of the cable joint is set to 1.5, 2, 3 and 4 mm respectively, and the thermo-electric coupling simulation was carried out. The maximum electric field near the high-voltage shielding tube with thickness of 1.5, 2, 3 and 4 mm is 2.97, 2.53, 2.19 and 2.07 MV/m respectively with the insulation temperature difference of the cable joint is 20 ^oC. Moreover, the stress cone curve of the cable joint was optimized, and the thermo-electric coupling simulation of the cable joint before and after optimization was carried out. According to the results, the axial electric field of the optimized stress cone is stable at about 0.04 MV/m, and the electric field distribution in the stress cone area is more uniform than that before optimization.

Conclusions

According to the optimization results, increasing the thickness of high-voltage shielding tube can effectively reduce the maximum electric field. Moreover, the expected electric field is realized and the DC electric field distribution in the stress cone area is effectively improved by optimizing the stress cone curve of cable joint. The conclusions can provide a reference for the DC transformation of the AC distribution XLPE cable joint.