Abstract

Cross-linked polyethylene, commercially known as XLPE, is widely used as an insulating material in high voltage cables. However, space charge accumulation under the DC field is one of the most challenging problems in the further development of XLPE insulated cable. Due to the potential electrical degradation ageing process triggered by the accumulated space charges, the IEEE standard 1732 was established for measuring space charge in HVDC extruded cables as the qualification tests. Previous research has revealed that space charge originates from either charge injection at the electrodes or ionization of impurities presenting inside the bulk. In the light of this, this paper aims to simulate the accumulation of space charge in XLPE under DC stress. Space charge measurements have been carried on the fresh and degassed XLPE samples. A modified bipolar charge transport model, by considering the dissociation of impurities, has been employed to simulate the space charge behavior in XLPE. Compared with the experimental observations, the simulation results can reveal appropriate features of hetero charge formation. Both the calculated charge dynamics and field variation are consistent with the experiment results. The restrictions and potential improvements of this preliminary model are also discussed for its future application of XLPE cables.

Highlights

  • High voltage direct current (HVDC) power transmission systems have been developed rapidly in recent decades, as this technology contributes to both large-capacity power transmission over long distance and the interconnection of regional power grids [1,2]

  • Both models areofimplemented by using which The is a general-purpose simulation charges enhanced the electric field near the cathode effectively, which could lead to more charge software using finite element analysis method (FEM) and applied for a number of scientific fields carriers being injected from the electrode

  • By considering the dissociation impurities, hetero charge for low density polyethylene (LDPE) and the estimated for dissociation, amount of hetero accumulated formation at both electrodesparameters can be simulated in XLPE the under the DC

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Summary

Introduction

High voltage direct current (HVDC) power transmission systems have been developed rapidly in recent decades, as this technology contributes to both large-capacity power transmission over long distance and the interconnection of regional power grids [1,2]. As the main component of the HVDC transmission, a number of HVDC cable technologies have been developed and deployed successfully around the world. DC stress could distort the electric field distribution in cross-linked polyethylene (XLPE) insulated cable [4,5]. By creating zones of high electrical field, space charge formation can accelerate the dielectric ageing process and even lead to early electrical failure [6,7]. Measurement, understanding, and modelling of space charge processes are essential, in order to calculate the electric field distribution in DC cables for a service lifetime estimation

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