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Effect of High Voltage Transients on Surface Discharge Characteristics of Oil-Paper Insulation
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.ORCID iD: 0000-0003-0759-4406
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
2015 (English)In: 2015 IEEE Electrical Insulation Conference (EIC), IEEE , 2015, 69-72 p.Conference paper (Refereed)Text
Abstract [en]

Condition assessment of power components such as power transformers and their bushings depends on the interpretation of data obtained from the monitoring systems. Various defects in their insulation would behave differently under electrical stresses. Surface discharge on the oil-paper interface is one of the defects which can be responsible for the failure of those components. Power system transients can impose stresses on the insulation of the power transformers and their bushings. This study investigates the effect of transients such as lightning impulses on the surface discharge characteristics of oil-impregnated paper. Two configurations, needle and rod (IEC-b), are used here. Two distinctive situations occur on paper due to these different configurations. The corresponding effect is shown in the form of variation in the partial discharge numbers and phase-resolved patterns. In the needle electrode configuration, the paper remains un-aged and the applied impulses cause a prompt change in the total number of discharges which decays fast. However, with the rod electrode, the paper gets carbonized and the applied impulses cause a decrease in the total number of discharges. The influence of moisture content in oil-impregnated paper was also studied. For this case, the total number of discharges considerably increase after applying impulse.

Place, publisher, year, edition, pages
IEEE , 2015. 69-72 p.
Keyword [en]
oil-impregnated paper, surface discharge, impulse, PD pattern
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-184568DOI: 10.1109/ICACACT.2014.7223489ISI: 000371481800014ISBN: 978-1-4799-7354-5OAI: oai:DiVA.org:kth-184568DiVA: diva2:916877
Conference
33rd IEEE Electrical Insulation Conference (EIC), JUN 07-10, 2015, Seattle, WA
Note

QC 20160405

Available from: 2016-04-05 Created: 2016-04-01 Last updated: 2016-05-25Bibliographically approved
In thesis
1. Dielectric Response and Partial Discharge Diagnostics of Insulation Systems by Utilizing High Voltage Impulses
Open this publication in new window or tab >>Dielectric Response and Partial Discharge Diagnostics of Insulation Systems by Utilizing High Voltage Impulses
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, power system transients are considered as an opportunity for development of on-line diagnostics of power components and specifically the insulation systems of power transformers and bushings.

A new technique for on-line dielectric response measurement of power transformer bushings is proposed which utilizes natural transients in the power system, such as lightning and switching surges, as stimuli. Laboratory investigations are done on implementation of the proposed technique. Measurement considerations, data acquisition and processing involved in achievement of reasonable accuracy in the Dielectric Response (DR) are presented. Capability of the technique in tracking of the degradation signatures such as moisture content in the insulation has been evaluated and it has shown a good level of accuracy by being compared to the Frequency Domain Spectroscopy (FDS). 

The proposed technique is tested on the service-aged 150 kV bushings and feasibility of the technique for monitoring of dielectric properties of power transformer bushings has been assessed; the results are promising for the technique to be used in the real application. 

Partial Discharges (PD) behavior under transients has been also studied for different materials in this project. PD behavior of different defects, at different insulation condition, responding to the overvoltage transients in form of superimposed impulses on ac voltages was investigated and it was perceived how their distinctive response and the interpretation of  that, can be useful for their identification.

Besides the conventional materials, surface ac PD properties of modified paper with silica and zinc oxide nanoparticles under the superimposed impulses have been assessed in this project. Proper type and optimum concentration level of nanoparticles in the paper are the factors that lead to the improvement of PD behavior in the modified paper under overvoltage transients.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. 79 p.
Series
TRITA-EE, ISSN 1653-5146 ; 2016:080
Keyword
Dielectric Response, Transients, Transformer bushing, Oil-impregnated paper, Moisture content, Partial discharge, Surface PD, Cavity PD, Superimposed impulse, Nanoparticles
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-187632 (URN)978-91-7729-033-9 (ISBN)
Public defence
2016-06-15, sal E3, Osquars backe 14, Stockholm, 14:00 (English)
Opponent
Supervisors
Note

QC 20160525

Available from: 2016-05-25 Created: 2016-05-25 Last updated: 2016-06-16Bibliographically approved

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