Interface Damages of Electrical Insulation in Factory Joints of High Voltage Submarine Cables

作者：Zhenpeng Zhang, Changji Zheng, Mei C. Zheng, Hong Zhao, Jiankang Zhao, Wei-Feng Sun, Junqi Chen · 发表于：Energies · 年份：2020 · DOI：10.3390/en13153892 · 被引用次数：23 · 研究领域：High voltage insulation and dielectric phenomena、Electrical Fault Detection and Protection、Advanced Sensor and Energy Harvesting Materials

As a key accessory of high-voltage (HV) insulated submarine cable, the factory joints of the cross-linked polyethylene (XLPE) represent an unpredictable uncertainty in cable-connecting fabrications by means of the extruded molding joint (EMJ) technique. The electrical breakdown pathways formed at the interfaces between recovery insulation and cable body under alternative current 500 kV voltages are specifically investigated by microstructure characterizations in combination with the electric field and fractal simulations. Dielectric-defected cracks in tens of micrometers in insulation interfaces are identified as the strings of voids, which dominate insulation damages. The abnormal arrangements of XLPE lamellae from scanning electron microscopy (SEM) imply that the structural micro-cracks will be formed under interface stresses. Electrical-tree inception is expedited to a faster propagation due to the poor dielectric property of interface region, manifesting as 30% lower of tree inception voltage. The longer free-paths for accelerating charge carriers in the cracks of interface region will stimulate partial discharging from needle electrodes. The carbonized discharging micro-channels arising in interface region illustrate that the partial discharging will be triggered by the electrical-trees growing preferentially along the defect cracks and could finally develop into insulation damages. The mechanism of forming cracks in the fusion processes between the molten XLPE of cable ...