Study on Partial Discharges Features Evolution of Underground Cable Joints during Insulation Degradation

Abstract

Underground cables are significant links in metropolitan power systems. Hence, any cable accident can cause high economic losses and disruption of service to customers. Recently, the condition-based maintenance (CBM) method proposed to improve the weakness of time-based maintenance becomes feasible in smart grid, which optimizes and improves the reliability of power systems. This paper focuses on analyzing the partial discharges evolution during insulation degradation and researching the proper features for the judgement in the status of condition monitoring. The experimental objects are 25 kV distribution underground cable straight joint containing one of two different type of artificial defects. The total experiment are 10 samples set including five defect X and five defect Y. The partial discharge measurement conducts according to the pulse current method of IEC 60270. Through the noise suppression, data simplification and feature extraction methods, each measured data becomes 104 features. By observing the evolution trend of each features, in the final stage the initial phase of the discharge area extends to the area, which is the voltage zero-crossing zone. This phenomenon might develop diagnostic rules for judging the transition of the insulation state, especially for final stage that is about to insulation breakdown. These diagnostic rules could provide the maintenance personnel simple instructions as an early warning for condition-based maintenance.

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Author Information
Chien-Kuo Chang, National Taiwan University of Science and Technology, Taiwan
Chang-Sing Lai, National Taiwan University of Science and Technology, Taiwan
Ruay-Nan Wu, National Taiwan University of Science and Technology, Taiwan

• Category: Energy: Renewable Energy and Environmental Solutions

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