Partial Discharge Behavior and Accelerated Aging Upon Repetitive DC Cable Energization and Voltage Supply Polarity Inversion

Montanari, Gian Carlo; Seri, Paolo; Bononi, S. Franchi; Albertini, M.

doi:10.1109/tpwrd.2020.2984766

Cited by 28 publications

(29 citation statements)

References 23 publications

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“…where is the gas pressure inside the cavity. This holds approximately also for cylindrical cavities, replacing with cavity height, ℎ , [2,3,5,13,[21][22][23]. For voltage transients, the PD repetition rate as a function of time, ( ), from beginning of the voltage transient (cable energization/voltage polarity inversion), 0 , to DC steady state condition, d , and can be estimated roughly as: (15) where d corresponds to steady state condition and 0 to the PD repetition rate in the initial instants of electric field variation, hence 0 = (0 + ).…”

Section: Partial Discharge Inception Field and Repetition Ratementioning

confidence: 81%

“…The supply voltage amplitude, 0 , is considered constant during load variation from 0 to d , being load the unique cause of the field transient. Regarding the transient time constant in (6), when the load decreases, the transient time constant can be calculated from (2) where d refers to the maximum load value (thus higher conductivity and shorter dielectric time constant). On the other hand, when the load increases, the thermal response is slower than that for cooling (see later Fig.…”

Section: Thermal Time Constant and Thermal Transientmentioning

confidence: 99%

“…Voltage transients caused, e.g., by energization and voltage polarity inversions give rise to electric field transients that may last hours [1][2]. Load variation, on the other hand, cause temperature transients inside insulation [3].…”

Section: Introductionmentioning

confidence: 99%

“…Inception of PD can degrade insulation locally, generating with time footpaths to insulation breakdown, so that failure can occur well in advance compared to the specified design life. This depends fundamentally on some factors which can be summarized by a damage concept: the longer PD are active and the higher the relevant energy (or power), the larger the contribution to life reduction [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

“…During electrical and thermal transients, the electric field profile in insulation and internal defects may vary significantly. There might be a significant difference in field profile between the conductivity-driven distribution, in DC steady-state, [5], and the permittivity-driven one, which establishes at the beginning of voltage (and sometimes load) transients [2,3]. PD might incept in insulation defects (cavities) during transients, but not in DC steady-state, if the insulation is designed properly to work (at any operating temperature) at nominal voltages below the DC steady-state partial discharge inception voltage, PDIVDC.…”

Section: Introductionmentioning

confidence: 99%

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Designing a HVDC Insulation System to Endure Electrical and Thermal Stresses Under Operation. Part I: Partial Discharge Magnitude and Repetition Rate During Transients and in DC Steady State

2021

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This paper has the purpose to investigate HVDC insulation design considering real operating conditions, when DC steady-state is affected by frequent voltage transients or load variations that may be present during all life. Electrical field distribution in insulation, and in insulation defects, may change significantly from DC steady-state when voltage and load vary with time, which can cause partial discharge activity often not been properly accounted for at the design stage. The Part I of this paper is dedicated to prove, through experiments, models and simulations, that electrical and thermal transients may incept partial discharges in defective insulations during cable energization, voltage polarity inversion at a constant nominal load, as well as during load variations at a constant nominal voltage. This can cause accelerated aging and premature breakdown even if the insulation system is designed properly to withstand DC electrothermal stress, without partial discharges in steady state, for all life, as it will be shown in Part II. Focus is on cables, but the approach described here is general for any DC insulation system. INDEX TERMS Cable insulation, DC, voltage and load transients, design methodology, finite element analysis, partial discharges. Hadi Naderiallaf was born in Mashhad, Iran, on April 16th, 1986. He received the M.Sc. degree in electrical engineering in 2012 from the Leibniz Universität Hannover, Germany. He did his master thesis at the Schering Institute of High Voltage Techniques and Engineering in the Leibniz Universität Hannover. He has working experience for five years as a transformer fluid specialist. From November 2017, he has been a PhD student in the University of Bologna in Italy working on the EU project GRIDABLE. His main research interests are liquid and nanostructured solid electrical insulating materials, HVDC cables design, space charge measurement and analysis, AC and DC partial discharge detection and modelling, insulation systems for electrical machines, condition monitoring techniques, HV transformer asset management, DGA and transformer oil reclamation. Paolo Seri (M'17) was born in Macerata, Italy, on June 4th 1986. He received the M.Sc. degree in energy engineering in 2012 and PhD in electrical engineering in 2016, both from the University of Bologna. From 2017 he is part of the Laboratory of Innovative Materials for Electrical Systems (LIMES) of the University of Bologna as a research fellow, currently working on the topics of HVDC cables design, partial discharge detection and modelling, and characterization of dielectric materials. He is also

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