Review Incident Shin.. - authority for electricity regulation, oman

Executive Summary
On 27 August 2007, at 22.07h a fault on the 132 kV-line of the Oman Electricity Transmission
Company SAOC (OETC) from Wadi Jizzi to Shinas led to an interruption of the power
supply in the Shinas area. This area was completely without power until 07.35 h the following
day, when the supply was partly restored via the 33 kV feeders of Majan Electricity
Company SAOC (MJEC) using a rota load shedding scheme. The Shinas 132 kV grid station
was energized again by OETC at 23.55 h on 28 August 2007. After that MJEC restored
the supply to all customers, which was completed at 01.34 h on 29 August 2007.
The Authority for Electricity Regulation, Oman (the Authority) asked KEMA to identify the
technical reasons for the interruption and investigate the overall management of the incident
by OETC. The Authority is of the view that the time taken by OETC to restore supplies
was unduly excessive.
We have studied several documents, including the incident reports/sequence of events of
both OETC and MJEC. Furthermore, we have interviewed representatives of both OETC
and MJEC, including both General Managers, OETC’s maintenance manager, representatives
of OETC’s Load Dispatch Center and responsible people on-site, such as OETC’s operation
engineer and MJEC’s local staff in the Sohar area.
The conclusions of our review can be summarized as follows:
the duration of the outage was influenced by a number of factors: the most important
being that the Wadi Jizzi – Shinas line was not (n-1) compliant as required by Oman
Transmission Security Standards and international best practice;
OETC was aware the Wadi Jizzi – Shinas line was not (n-1) compliant but did not have
a comprehensive plan in place to detect faults. Fault distance indicators installed at the
Wadi Jizzi grid station could have reduced the time taken to locate the fault and reduce
the duration of the supply interruption;
Since we have only seen an expired maintenance contract, we are unable to confirm
that a maintenance contract for the Wadi Jizzi – Shinas line was in place at the time of
the incident;
spare parts were not immediately available on site and had to be transported from remote
locations. This contributed to the supply interruption being longer than necessary.
The fault was located at 1.00 am whereas spare parts arrived on-site at 4.30 pm. Some
14 hours was lost by not having spare parts available close to the site;
organization of the emergency response effort was ad-hoc and poorly organized - it was
not always clear who was in charge for coordinating the restoration activities and some
Review Incident Shinas August 2007 2 09.10.2007
vs. 2 (final)