Online Condition Monitoring of Partial Discharge in HV Underground by dwv40440


									  Online Condition Monitoring of Partial Discharge in HV
                   Underground Cables
                          A. S. Ayub1, W. H. Siew2, J. J. Soraghan3
                            University of Strathclyde, Glasgow, UK

Abstract - Partial discharges are symptomatic of many degradation phenomena in power cables and
may cause further deterioration of the insulation in many cases. These symptomatic problems can be
detected by using online and offline technique. However, both techniques have its own disadvantages
e.g. noise, interference, partial discharge location, sensor optimisation and economical point of view. In
order to minimise these, continuous monitoring of the insulation condition through online is therefore
desirable i.e. partial discharge detection and location.


    Transmission and distribution of large                  The research survey found that the main
quantities of power, as in power networks,              issue considered by most authors was
can be established using overhead lines or              location and detection in power cables
underground cables. Underground cables                  during online operation. Economic issues
accommodate various voltages and power                  were also considered by some authors, but
levels. Although overhead lines are                     to a lesser extent. Other issues, such as
preferred from the investment-costs                     signal extraction, noise and interference,
perspective, other factors such as aesthetic            were considered briefly but not analysed in
and environment considerations, safety                  detail. Therefore there was a clear need for
issues, regulations and technical, favours the          this project to investigate issues related to
underground cables. Moreover, cables are                signal extraction, noise and interference in
also competitive if operation costs including           detail.
maintenance are put into account i.e.                       Various monitoring and diagnostic
condition based maintenance.                            techniques have been utilised for the
    The application of condition-based                  condition monitoring of HV power cables.
maintenance strategies can prevent outages              However, there are some limitations for
from cable failures, and offers substantial             each technique. For instance, insulation
savings for network utilities and enhanced              resistance and dielectric loss measurements
power supply reliability. Among these                   are useful for the assessment of average
methods, the partial discharge (PD)                     insulation condition of the whole cable, but
detection provides a non-intrusive and                  may not be sensitive to local insulation
mostly non-destructive technique to identify            defects. It is therefore the objectives of the
incipient failure of components.                        authors to further improve these techniques
    Generally, PD are discharges that bridge            and develop new and innovative techniques
only part of the insulation material in a cable         which are more reliable and widely
or accessory and are indicative of the local            acceptable for cable condition assessment.
insulation condition and it occurs at defects           With the aid of sophisticated analysis
such as air filled cavities and it leads to             programs, the condition of power cables can
deterioration. Therefore, accurate mapping              be more accurately determined to avoid
of weak components within the system is                 catastrophic failures in high voltage cable
crucial as cable connections do not degrade             networks.
uniformly. In addition, partial discharges
can be measured electrically, acoustically
and optically.

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