Towards predictive monitoring of HVDC Cables: An integrated system for stress, partial discharges and ageing assessment

DC-specific partial discharge (PD) detection, and (3) ageing assessment via dielectric loss analysis. The first module utilizes voltage, current, and distributed temperature sensing (DTS) data to model the dynamic electric field profile along the cable, identifying conditions that may lead to critical stress. The second module enables PD detection under DC conditions by correlating the time evolution of PD activity with local electric field variations, accounting for hypothetical cavity effects and classifying pulses by waveform and timing. This approach was validated experimentally on a full-scale HVDC cable with an artificial defect, where PD repetition rate closely followed the calculated electric field trend, confirming the reliability of the Electric Field Resolved PD (EFRPD) pattern. The third module estimates dielectric losses by analysing radial heat flux using dual-fibre DTS and conductor current measurements, providing early warning of insulation ageing and pre-fault conditions. Experimental validation demonstrated that dielectric losses increased gradually under normal operation but exhibited a sharp rise prior to breakdown, highlighting the system’s effectiveness in early fault detection.

Overall, the proposed monitoring system offers a comprehensive solution for predictive maintenance and asset management of HVDC cables, supporting the development of an

HVDC-specific Health Index.