DC Partial Discharge Characteristics of MVDC Cable Terminations Considering Multi-Layer Interfaces Defect

Abstract

The introduction of DC power grids in Korea has led to the need for partial discharge (PD) detection methods for various DC power devices. However, research on DC remains in its early stages domestically, resulting in insufficient information into DC PD for each power device. In this paper, experiments were conducted on DC PD caused by creepage defects between multi-layer interfaces at the cable termination of XLPE cables in DC conversion facilities. Partial discharge simulation defect electrodes were constructed by modeling the EPDM/XLPE multi-layer interfaces of a cable termination's stress cone, with creepage configurations considering two different lengths. Prior to the experiment, Partial Discharge Inception Voltage (PDIV) and breakdown voltage(BDV) values were measured for each condition. Subsequently, PD was measured by applying PDIV, BDV-based DC voltages, and the characteristics of the measured DC PD data for each condition were analyzed. Experimental results confirmed that the incidence rate of surface discharge defects and the average discharge magnitude between multi-layer interfaces increase with the applied voltage and creepage length. The partial discharge pulse waveforms were similar in shape under all conditions. © 2024 The Korean Institute of Electrical Engineers (KIEE).