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Reliability Engineering Methods for Distribution Systems - Influence of Differences between Cable Systems and Overhead Lines

Guldbrand, Anna LU (2007) In TEIE 7218.
Abstract
One way to increase distribution network reliability is to replace traditional overhead lines

with underground cables. To fully utilize these investments, network owners will have to

adjust their reliability engineering methods to suit the new cable networks. In this paper

different condition assessment methods as well as improved failure statistics for cable systems

are considered. The paper is based on information from project reports and scientific papers.

In addition a number of Swedish distribution network owners have been asked to share their

opinion of reliability engineering work of today and the future.

The methods used for distribution system condition assessment... (More)
One way to increase distribution network reliability is to replace traditional overhead lines

with underground cables. To fully utilize these investments, network owners will have to

adjust their reliability engineering methods to suit the new cable networks. In this paper

different condition assessment methods as well as improved failure statistics for cable systems

are considered. The paper is based on information from project reports and scientific papers.

In addition a number of Swedish distribution network owners have been asked to share their

opinion of reliability engineering work of today and the future.

The methods used for distribution system condition assessment change as overhead lines

are replaced by underground cable. Visual inspections can no longer be used and diagnostic

methods are instead introduced. The diagnostic methods are costly to perform. To become

frequently used they must prove to be efficient enough to justify the financial means required.

New, improved, diagnostic methods are under development and since most cable failures are

related to component properties the use of diagnostic methods is likely to increase.

Statistics show that a majority of the cable system failures are ageing failures. The ageing

failures do not to any large extent depend on environmental factors but on component

properties. This implies that component lifetime standard deviation decreases as component

data are related to the statistics, yet failure statistics is at present not related to component

data. A majority of the network owners contributing to this paper agree that the nature of

cable failures, except excavation failures, makes it interesting and useful to related cable data

to failure statistics and to share the statistics with other network owners.

Several Swedish distribution network owners are in the process of installing new program

for network analysis. One challenge is to decide which component data that shall be related to

the failure statistics. Operational age, maintenance history, manufacturer and year of

manufacturer are four manageable factors which influence on failure statistics is already

established but yet not thoroughly evaluated. In addition the method of cable excavation is

suggested as a fifth interesting factor related to cable system reliability. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Book/Report
publication status
published
subject
in
TEIE
volume
7218
publisher
Department of Industrial Electrical Engineering and Automation, Lund Institute of Technology
external identifiers
  • other:CODEN:LUTEDX/(TEIE-7218)/1-14/(2007)
language
English
LU publication?
yes
id
d42bddde-7a06-4c23-9dc1-6fbf43929667 (old id 588103)
alternative location
http://www.iea.lth.se/publications/Reports/LTH-IEA-7218.pdf
date added to LUP
2007-10-30 12:05:53
date last changed
2016-04-16 10:00:36
@techreport{d42bddde-7a06-4c23-9dc1-6fbf43929667,
  abstract     = {One way to increase distribution network reliability is to replace traditional overhead lines<br/><br>
with underground cables. To fully utilize these investments, network owners will have to<br/><br>
adjust their reliability engineering methods to suit the new cable networks. In this paper<br/><br>
different condition assessment methods as well as improved failure statistics for cable systems<br/><br>
are considered. The paper is based on information from project reports and scientific papers.<br/><br>
In addition a number of Swedish distribution network owners have been asked to share their<br/><br>
opinion of reliability engineering work of today and the future.<br/><br>
The methods used for distribution system condition assessment change as overhead lines<br/><br>
are replaced by underground cable. Visual inspections can no longer be used and diagnostic<br/><br>
methods are instead introduced. The diagnostic methods are costly to perform. To become<br/><br>
frequently used they must prove to be efficient enough to justify the financial means required.<br/><br>
New, improved, diagnostic methods are under development and since most cable failures are<br/><br>
related to component properties the use of diagnostic methods is likely to increase.<br/><br>
Statistics show that a majority of the cable system failures are ageing failures. The ageing<br/><br>
failures do not to any large extent depend on environmental factors but on component<br/><br>
properties. This implies that component lifetime standard deviation decreases as component<br/><br>
data are related to the statistics, yet failure statistics is at present not related to component<br/><br>
data. A majority of the network owners contributing to this paper agree that the nature of<br/><br>
cable failures, except excavation failures, makes it interesting and useful to related cable data<br/><br>
to failure statistics and to share the statistics with other network owners.<br/><br>
Several Swedish distribution network owners are in the process of installing new program<br/><br>
for network analysis. One challenge is to decide which component data that shall be related to<br/><br>
the failure statistics. Operational age, maintenance history, manufacturer and year of<br/><br>
manufacturer are four manageable factors which influence on failure statistics is already<br/><br>
established but yet not thoroughly evaluated. In addition the method of cable excavation is<br/><br>
suggested as a fifth interesting factor related to cable system reliability.},
  author       = {Guldbrand, Anna},
  institution  = {Department of Industrial Electrical Engineering and Automation, Lund Institute of Technology},
  language     = {eng},
  series       = {TEIE},
  title        = {Reliability Engineering Methods for Distribution Systems - Influence of Differences between Cable Systems and Overhead Lines},
  volume       = {7218},
  year         = {2007},
}