Study on the Effect of Void Geometry and Location on Electric Field Distribution and Partial Discharges in HVDC Cables

Nowadays HVDC transmission systems are preferred over HVAC systems because of their less power loss and high reliability. In the HVDC cable transmission system, there is a problem of Partial Discharges (PD) occurring due to cavities of the dielectrics in HVDC cables. The distribution of the electric field may change in the presence of partial discharge, which has an impact on how the electric system normally functions. Under DC conditions, partial discharge characteristics are influenced by the electric field distribution and electrical conductivity. Discharges tend to occur quickly when the cavity field reaches the inception level. Hence it is necessary to monitor the conditions of the HVDC cable for better transmission. A 2-D FEM-based model is developed for the simulation of PD due to various shapes of voids at various locations in the cable insulation using ANSYS. Also, PD modeling is the most important concern in identifying the influencing parameters and physical mechanisms of the PD phenomenon. In this work, the Three capacitances model is used to estimate the model parameters and simulate the partial discharges in MATLAB. The results from the simulation are compared with analytical models. It is observed that pulses of the partial discharges vary with the dimensions of the void, type of void materials, and location of the void.