Broadband impedance spectrum detection of buffer layer defects in 110 kV crosslinked polyethylene cable with corrugated aluminium sheath

The cross‐linked polyethylene insulated cables with corrugated aluminium‐sheathed are widely used in urban power systems. Recently, a new type of power cable fault has emerged, primarily due to defects in the buffer layer. However, there is a notable lack of effective evaluation methods for these defects in high‐voltage (HV) cables. Initially, a theoretical analysis of the gas generation mechanism in the cable buffer layer was conducted, identifying distinct gas products at different stages. Subsequently, the diffusion kinetics of gas within the cable was studied, highlighting the importance of gas in determining the state of the buffer layer. The authors then collected and analysed 60 sets of buffer layer gases from two operational 110 kV HV cables using gas chromatography technology. Combining these results with the findings from on‐site inspections, the characteristic gas components and concentration distribution under various defect conditions were summarised. The results found higher concentrations of CH4 in normal cables and defective cables, while there are higher concentrations of H2, CO and CO2 in defective cables, and the oxygen content decreases. The discoveries made in this research may offer a new approach for assessing the state of the cable buffer layer.

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Revitalising high voltage cable: Exploring effective repair methods and influential factors for buffer layer defects using conductive silicone rubber

Yin,

Zhou,

et al. 2024

High Voltage

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In recent years, the ablative discharge of the buffer layer in high‐voltage (HV) cross‐linked polyethylene (XLPE) cables has become a significant challenge for the operation and maintenance of power lines. However, there is a lack of effective methods to address buffer layer discharge defects. A practical approach is proposed to repair buffer layer defects and mitigate the associated discharge issues. To achieve this goal, the principles of repairing buffer layer defects are analysed by establishing an electrical network model that considers different contact states between the buffer layer and aluminium sheath. Based on this analysis, a method involving the injection of solidifiable rejuvenation fluid between the buffer layer and aluminium sheath is proposed to effectively suppress buffer layer discharge defects. Through simulation calculations, the minimum electrical conductivity and injection volume required to establish a reliable electrical connection between the buffer layer and aluminium sheath is determined. Additionally, a curable rejuvenation fluid containing conductive carbon black silicone rubber is prepared and analysed for its conductivity and flow properties at both the mesoscopic and macroscopic levels. Finally, a real cable office discharge test is conducted to compare the discharge behaviour of defective cables before and after repair. The results demonstrate that when the conductivity of the rejuvenation fluid exceeds 10−6 S/m, it effectively establishes a conductive channel between the insulation shield and aluminium sheath, thereby reducing the risk of discharge ablation. Furthermore, after injecting the rejuvenation fluid and completely covering the white mark defect, the discharge phenomenon in the buffer layer is significantly suppressed, leading to the restoration of its electrical performance.

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Broadband impedance spectrum detection of buffer layer defects in 110 kV crosslinked polyethylene cable with corrugated aluminium sheath

Cited by 7 publications

References 16 publications

Effect of micrometer bubble interfaces on the detection and measurement method of XLPE

Effect of micrometer bubble interfaces on the detection and measurement method of XLPE

Gas production analysis for the buffer layer of high‐voltage cross‐linked polyethylene cables

Revitalising high voltage cable: Exploring effective repair methods and influential factors for buffer layer defects using conductive silicone rubber

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