Molokai residents can expect relief from major power outages after Maui Electric Co. identified and fixed the underlying causes of the outages that struck the island last year and this year, utility officials said.
The electric company submitted a report to the state Public Utilities Commission last week, disclosing that a revised load-shedding scheme and a faulty wire connection on a generation unit were to blame for the increased number of power outages -19 major outages in 2013 and 12 in the first four months of this year. These numbers are up from the average of 8.5 outages per year in the previous four years on Molokai, according to the report.
"These outages were a significant disruption for our Molokai customers, and we made it a top priority to do everything possible to resolve the situation," said MECO spokeswoman Kau'i Awai-Dickson in an email Wednesday. "As we shared with the community at our Molokai public meetings in January and May, we are strongly committed to providing our customers with electrical service that they can count on."
"We are confident that through the steps taken, we have been able to restore system reliability for the island of Molokai, and we will continue our efforts to maintain the level of service our customers expect and deserve," Awai-Dickson added.
The report filed by MECO comes after an April 28 order issued by the commission calling for an investigation to look into the reliability standards for Hawaiian Electric Co.'s subsidiary, Maui Electric Co., specifically the 2013 and 2014 outages on Molokai. It also asks for MECO to supply a report regarding the outages as well as steps the company is taking to improve the resiliency of the Molokai grid in light of the rapid adoption of customer-sited photovoltaic systems.
MECO called the causes of the outages "unusual."
One cause was a "revised under frequency load-shed" scheme implemented in May 2013 to respond to the changing dynamics of the Molokai grid.
(Load shedding is a way for the company to shut down power over different parts of a distribution region, usually done to avoid a total blackout and damage to the power grid.)
The initial revised scheme was implemented to reduce the probability of a cascading islandwide outage, the report said. The revised scheme worked as designed for the first six months following implementation, "but unusual tripping of circuits started to occur in November."
The company determined revised safe protection settings, and changes were implemented in January.
MECO is continuing to monitor and make adjustments to the system protection scheme.
The second cause of the outages was a broken wire inside a connector that was discovered during a generator maintenance check in February.
Because the condition of the broken wire was intermittent, hidden and did not trigger any alarms, the problem was extremely difficult to detect, but it has been repaired, the report said.
Other outages were the result of severe weather earlier this year, failure of certain equipment and car accidents, MECO said.
MECO also points to Molokai's limited number of circuits, low system loads and no interconnection to another system as factors that limit the Molokai system's ability to ride through faults and generation disturbances.
It added that the "high penetration" of customer-sited photovoltaic systems was not the direct cause of the outages, although MECO continues to institute and improve upon mitigation measures to "address the fragility of the Molokai grid" because of the high level of solar power usage on the island.
Awai-Dickson said MECO has taken measures to modernize and improve its system such as upgrading its generating units and enhancing its data collection and communications systems.
MECO is upgrading its distribution system in Kaunakakai, and it continues to explore ways to add more solar power to the Molokai grid, she added.
In partnership with the Hawaii Natural Energy Institute, MECO is working on installing a battery on Molokai to further support its electric grid.
MECO is consulting with photovoltaic inverter manufacturers to enable improved load control when there is a problem on the system, such as a downed tree on power lines, Awai-Dickson said.
* Melissa Tanji can be reached at firstname.lastname@example.org.