A study on the origin of space charge accumulation in polymeric HVDC cables

Carstensen, P.; Jönsson, Jan Åke; Farkas, A.A.; Campus, A.; Nilsson, U.H.

doi:10.1109/icsd.2004.1350340

Cited by 6 publications

(2 citation statements)

References 2 publications

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“…Space charges can be trapped in the polymer. From a chemical point of view, the peroxide decomposition products facilitate the trap presence [14], [15] and heterocharges [16]. In our study, this assumption cannot be verified through space charge measurements because the samples have been degassed before measurement and the high poling temperatures used (above 70°C) could favor the degassing of the possible remaining species.…”

Section: B Study Of Volume Conduction Phenomenamentioning

confidence: 81%

Study and analysis of conduction mechanisms and space charge accumulation phenomena under high applied DC electric field in XLPE for HVDC cable application

Hascoat

Castellon

Agnel

et al. 2014

2014 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP)

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The development of High Voltage Direct Current (HVDC) cables requires design according to specific criteria and materials with appropriate properties. Cross-linked polyethylene (XLPE) has established itself over the past 20 years as the most used insulation material for HVAC cables, but also more recently for HVDC cables. If the electrical properties of this polymer have been widely studied under AC stress, the behavior of these materials under high DC stress is less known and needs thorough investigation. It is well known that, in DC conditions, the electric field distribution is highly dependent on operating conditions (thermal gradient and electric field) and can be affected by electric charges trapped in the insulation. The resulting space charge accumulation is able to increase significantly the local electric field, thus accelerating ageing and increasing the risk of breakdown. Consequently, the influence of electrical and thermal stresses on the material properties could be a key parameter on the ageing law for HVDC insulating material.The purpose of the present work is to investigate the dielectric behavior of XLPE insulation under different combined thermal and DC electrical stresses. The first step is to evaluate the volume electrical conduction and interface injection mechanisms by using current versus voltage (I-V) measurements. The second step is to investigate the development of space charges by using a non-destructive space charge measurement technique (the Thermal Step Method).

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Section: B Study Of Volume Conduction Phenomenamentioning

confidence: 81%

Study and analysis of conduction mechanisms and space charge accumulation phenomena under high applied DC electric field in XLPE for HVDC cable application

Hascoat

Castellon

Agnel

et al. 2014

2014 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP)

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“…The space charge development is known to have a critical impact on the lifetime and the evaluation of the aging degree of insulation materials under high DC stress [ 10 ]. Its transport is closely associated with hopping charge carriers [ 11 , 12 , 13 ]. While the thermal aging process will significantly change the trap characteristics of polymer materials, which directly leads to different space charge behaviors [ 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

Space Charge Behavior of Thermally Aged Polyethylene Insulation of Track Cables

Qiao

Wang³

et al. 2022

Polymers

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The interface of multi-layer insulation is a relatively weak point in the cable system during the long-term high-temperature service. Space charge is prone to continuously accumulate in the interface area, leading to the deterioration of electrical properties and even insulation failure in advance. The knowledge about thermal oxidation of polyethylene (PE) materials at the molecular level is still urgent to explore. Herein, single-layer and double-layer PE insulation, representing the typical insulation structure of frequency-shift pulse voltage track cables, were prepared and thermally aged in the oven for up to 360 h. Thermal, mechanical, electrical, and space charge characterizations were systematically carried out. Thermogravimetric analyzer and oxidation induced temperature (OIT) measurements confirmed that LDPE’s thermal-oxidative aging temperature range was the lowest among the three PE groups in the O2 atmosphere. After 360 h thermal aging, the tensile property of HDPE material kept relatively stable, while the elongation at break of the other two groups was lower than 50%. Unaged HDPE exhibits apparent charge injection and migration, leading to the severe electric field distortion of 20%. Noticeable charge accumulation can be observed at the unaged double-layer sample interface due to the mismatching of DC conductivity, which play a significant role in the aged double-layer samples. This work utilizes precise thermal analysis to provide new information about the resistance ability of thermal oxidation of LDPE, FPE, and HDPE, and its influence on space charge behaviors, which is helpful for the insulation design and evaluation in cable applications.

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