Electrical Performance of High-Voltage Cable Semiconductive Buffer Layer and Its Influence on Electric Field Distribution

Discharge and ablation failures have been observed in buffer layers of both domestic and international corrugated aluminum-sheathed high-voltage cross-linked polyethylene (XLPE) insulated cables, and electrical properties of the buffer layer are crucial factors influencing its operational performance. From the perspective of two different buffer layer materials, tests were conducted to measure volume resistivity of semiconductive polyester non-woven water-blocking fabric and semiconductive butyl rubber tape under varying temperatures, pressures, and moisture conditions. A two-dimensional axisymmetric model of a 110 kV corrugated aluminum-sheathed XLPE insulated cable was established to analyze the effects of buffer layer volume resistivity, the number of poor-contact points, and the structure of semiconductive butyl rubber tape on electric field intensity in the buffer layer. Experimental results indicated that with the increase in temperature, pressure and moisture, volume resistivity of the buffer layer tended to increase, potentially exceeding standard limits. Simulation results showed that when buffer layer was in close contact with corrugated aluminum sheath, changes in its volume resistivity had a minimal impact on electric field distribution at the buffer layer. However, when poor contact existed between buffer layer and corrugated aluminum sheath, electric field intensity at the buffer layer increased with the number of poor-contact points. This increase could become more pronounced when volume resistivity of the buffer layer exceeded standard values. Additionally, inclusion or exclusion of the butyl rubber tape structure had little effect on electric field distribution between buffer layer and corrugated aluminum sheath, and its addition did not fundamentally resolve discharge and ablation failures in this region.