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

We report on a self-consistent numerical analysis campaign of partial discharge (PD) ignition in H 2 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 S...

Full description

Saved in:
Bibliographic Details
Published in:IEEE transactions on dielectrics and electrical insulation 2024-10, p.1-1
Main Authors: Kourtzanidis, Konstantinos, Dimitrakellis, Panagiotis, Rakopoulos, Dimitrios
Format: Article
Language:English
Subjects:
bubble
dielectric fluid
Dielectrics
Electric fields
Electrons
Mathematical models
Oil insulation
partial discharge
Partial discharges
plasma simulation
Plasmas
Power transformer insulation
transformer oil
Vegetable oils
Windings
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We report on a self-consistent numerical analysis campaign of partial discharge (PD) ignition in H 2 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 (V RMS = 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.
ISSN:1070-9878
DOI:10.1109/TDEI.2024.3478130