Flexible UHF Antenna Sensor for Partial Discharge Detection of High-Voltage Cable Joints

Partial discharge (PD) detection is essential for maintaining the reliability and operational safety of high-voltage (HV) power systems by identifying insulation degradation before catastrophic failure occurs. Conventional PD detection systems often depend on rigid antennas, which are difficult to install on HV cable joints and curved surfaces of HV equipment. To address this limitation, a flexible polyimide-based ultra-high-frequency (UHF) planar antenna sensor is presented in this work. The multi-layer, flexible substrate-based sensor is experimentally validated for PD detection on Cross-Linked Polyethylene (XLPE) cable joints. The antenna features a multi-stacked substrate-based coplanar waveguide (CPW) design. Under extreme bending conditions (35 mm bending radius), it can maintain 0.91-3 GHz UHF band coverage with an average gain of 2.44 dB. During PD detection tests, the proposed antenna sensor recorded significantly higher signal amplitudes compared to the conventional high-frequency current transformer (HFCT) method, demonstrating its suitability for field applications with reliable fault detection capability. The proposed sensor has a dimension of 146 mm × 100 mm and a total thickness of 0.675 mm only. Under extreme bending scenario, it can withstand mechanical deformation, keeping its performance satisfactory compared to other flexible PD sensors. In this work, the proposed flexible PD sensor is optimized, fabricated, measured and tested on XLPE cable joint for early detection of PD which offers a practical solution for on-site PD monitoring to ensure the predictive maintenance and safe operation of HV systems.