The effect of grafted additives on space charge characterization of hot-pressed polypropylene blends for HVDC cable insulation

In modern power grids, High Voltage Direct Current (HVDC) links are increasingly utilized for efficient long-distance electricity transmission. Polymeric materials, particularly polypropylene (PP), are commonly employed as insulation due to their lightweight, durable, and effective insulating properties. However, a critical challenge with these materials is space charge accumulation, where trapped electric charges distort the internal electric field, leading to insulation degradation, reduced reliability, and shortened lifespan of HVDC systems.This study investigates the development of thermoplastic minicompounds aimed at mitigating space charge in HVDC cables through the use of PP blends. Six hot-pressed PP-based blends were tested to analyze space charge behavior, including homo- and hetero-charge formations, trap depths, and charge relaxation dynamics. The findings demonstrated significant reductions in space charge accumulation and improved insulation strength across the tested compounds, with the highest trap depth recorded at 0.95 eV. This study contributes to advancing the understanding of space charge dynamics in HVDC cables, highlighting the importance of optimizing polypropylene blends for improved insulation performance. Future work should focus on large-scale testing and further material optimization to support the development of cost-effective, sustainable, and reliable HVDC insulation solutions.