Numerical analysis of partial discharge ignition in H2 bubbles floating in dielectric oils, for High-Voltage Solid State Transformer applications

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Main Authors: Kourtzanidis, Konstantinos, Dimitrakellis, Panagiotis, Rakopoulos, Dimitrios
Format: Preprint
Published: 2024
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author Kourtzanidis, Konstantinos
Dimitrakellis, Panagiotis
Rakopoulos, Dimitrios
author_facet Kourtzanidis, Konstantinos
Dimitrakellis, Panagiotis
Rakopoulos, Dimitrios
contents We report on a self-consistent numerical analysis campaign of partial discharge (PD) ignition in H2 bubbles floating in biobased dielectric oils. We investigate various configurations (bubble sizes, bubble position, existence of protrusion) on a cylinder-to-cylinder setup that emulates a specific SST module (from SSTAR Horizon Europe project) under transient overvoltage as well as in its design operational conditions (VRMS = 66 kV, AC excitation of 50 Hz). Our results on electrical characteristics and plasma dynamics leading to the PD ignition, indicate that under transient overvoltage and for mm size bubbles (diameter 1 -4.5 mm), the smaller the bubble the less the inception voltage, while the peak inception voltage is higher than 70 kV. The existence of metallic protrusion can affect the inception voltage of a remote floating bubble only slightly and when this is close to the sharp tip. The extreme scenario of a protrusion in contact (inside) a gas bubble severely affects the insulation properties and drops the PD inception voltage remarkably. The larger the bubble and the sharper the tip of the protrusion the lower the inception peak voltage, that can reach values well below 40 kV. On the contrary and under design operation, larger bubbles increase the severity and probability of PD events, leading to lower instantaneous inception voltages. Current pulses produced in bubbles can quickly transit to intense streamer discharges (which can also transit to catastrophic arcing) if the operational frequency is reduced and/or under transient, HF overvoltage.
format Preprint
id arxiv_https___arxiv_org_abs_2410_05927
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Numerical analysis of partial discharge ignition in H2 bubbles floating in dielectric oils, for High-Voltage Solid State Transformer applications
Kourtzanidis, Konstantinos
Dimitrakellis, Panagiotis
Rakopoulos, Dimitrios
Plasma Physics
Computational Physics
We report on a self-consistent numerical analysis campaign of partial discharge (PD) ignition in H2 bubbles floating in biobased dielectric oils. We investigate various configurations (bubble sizes, bubble position, existence of protrusion) on a cylinder-to-cylinder setup that emulates a specific SST module (from SSTAR Horizon Europe project) under transient overvoltage as well as in its design operational conditions (VRMS = 66 kV, AC excitation of 50 Hz). Our results on electrical characteristics and plasma dynamics leading to the PD ignition, indicate that under transient overvoltage and for mm size bubbles (diameter 1 -4.5 mm), the smaller the bubble the less the inception voltage, while the peak inception voltage is higher than 70 kV. The existence of metallic protrusion can affect the inception voltage of a remote floating bubble only slightly and when this is close to the sharp tip. The extreme scenario of a protrusion in contact (inside) a gas bubble severely affects the insulation properties and drops the PD inception voltage remarkably. The larger the bubble and the sharper the tip of the protrusion the lower the inception peak voltage, that can reach values well below 40 kV. On the contrary and under design operation, larger bubbles increase the severity and probability of PD events, leading to lower instantaneous inception voltages. Current pulses produced in bubbles can quickly transit to intense streamer discharges (which can also transit to catastrophic arcing) if the operational frequency is reduced and/or under transient, HF overvoltage.
title Numerical analysis of partial discharge ignition in H2 bubbles floating in dielectric oils, for High-Voltage Solid State Transformer applications
topic Plasma Physics
Computational Physics
url https://arxiv.org/abs/2410.05927