Study on Electric Field Distribution of Buffer Layer Within HVDC Cables Considering the Piezoresistive Effect

The piezoresistive effect of the water blocking buffer layer of high-voltage cables is studied in this paper. Quantitative relationship between the volume resistivity and the surface pressure of the buffer layer is investigated. Results indicate that when the compressive stress of the buffer layer changes from 0 to 0.612MPa, the compressive strain exhibit a power law function, rising from 0 to 0.742. As the compressive stress of the buffer layer increases, its volume resistivity rapidly decreases, which cannot be considered as a constant. Considering the piezoresistive effect of the buffer layer, the electric field distribution in the buffer layer of 200 kV HVDC cable is simulated. It is found that the field strength in the buffer layer of normal HVDC cable is far from the initial field strength of discharges. The electric field simulation results of the buffer layer considering the piezoresistive effect are more accurate, which has important theoretical significance for the study of the ablation mechanism of the buffer layer.