Power outages part of local energy disruption report
Among the interesting data reported in the assessment of American Samoa’s energy supply disruption are the most frequent causes of short-term power outage in the territory and the total power outages over two fiscal years.
The comprehensive assessment report title ‘Addressing the Threat of Long-Term Energy Supply Disruption: A Strategic Energy Assurance Plan (EAP) for American Samoa’ was conducted by the U.S. base Westmoreland Associates.
According to the report — released this summer — data from the American Samoa Power Authority shows that the most frequent causes of short-term power outages to ASPA generation and distribution systems from 2008 to 2010 were:
• elevated cooling water temperatures;
• tripping of temporary Aggreko units (used at the Tafuna power plant following the September 2009 tsunami that destroyed the Satala power plant);
• under-frequency causing feeders to trip;
• fallen tree branches and electrocuted birds;
• malfunctioning components such as blown transformers, a broken primary jumper, a faulty liquid vacuum switch, etc.; and
• a number of causes reported only as “unknown”.
The report went on to say that the total number of customer-outages in FY 2008 was reported by ASPA as 35,710; in FY 2009 the number was 35,697, and in FY 2010 the number of customer outages was almost 55,000.
“Depending on circumstances of each outage, some customers may have suffered multiple outages while others experienced only a single outage, while still others may have not experienced an outage in electrical service at all in a given year,” it says.
Moreover the leap in customer-outages in FY 2010 reflects the continued, post-tsunami load stresses placed on the Tafuna station when the Satala power plant was destroyed by the 2009 tsunami.
“When electrical outages occur, those customers with back-up generators are able to continue operations at least on an emergency, short-term basis,” it says. “Other customers have no choice but to await system repairs that allow for resumption of service.”
It also explained that whenever unplanned outages occur on the ASPA grid or anywhere else in the system, ASPA has the ability to shut down individual feeders, and sections of the distribution system are then prioritized and cut off to the extent needed to allow repairs on the disrupted areas to occur efficiently and safely.
The report also explained the process ASPA goes through when there is an outage. It says that the electrical systems operation data are personally monitored by an operator 24 hours a day, seven days a week.
Whenever system outages are observed, they are reported by an on-site monitor with problems being communicated through a chain-of-command to the ASPA chief executive officer.
“ASPA is expecting FEMA to provide an upgrade to this system to allow an improved supervisory access element for capturing and responding to outages,” according to the report, which pointed out that at the time it was being prepared, there remained a continuing challenge for ASPA to deliver firm, reliable electrical power across Tutuila island due to system stressors created by the 2009 disaster.
At the same time, ASPA must contend with ongoing and historical system vulnerabilities due to weather, accidents, malfunctioning due to equipment age or overuse and delayed operation and maintenance.