A generating unit with past reliability challenges was the cause of electrical service interruptions in the St. Thomas – St. John district on both Sunday and Monday, the Water and Power Authority announced Monday night in a news release.
The performance of Unit 26, a 25-megawatt rental unit, has been questionable, and the unit has not been used by WAPA to satisfy electrical demand until the last few days. Although some modifications had recently been made to its fuel pressure systems, and its performance had generally improved, WAPA has been reluctant to dispatch it, the release said.
“WAPA options were limited over the past few days, and we could not avoid dispatching Unit 26 given that another rental, Unit 25, was on a scheduled maintenance, and two WAPA-owned gas turbines, Units 15 and 23, were not available,” said Chief Operating Officer of Electric Systems Clinton T. Hedrington, Jr.
Hedrington said repairs to Unit 15’s fuel systems were completed Monday, and the unit was dispatched to assist in the restoration from a second outage this evening.
Unit 23 is awaiting a component for its starting system, the part is on order, and should be on- island this week, he said.
“Our preference is to dispatch Units 15 and 23 once available, and avoid the use on Unit 26 until such time that its reliability has been proven,” Hedrington said. “Together with 15 or 23, we also dispatch the propane-fired Wartsila generators. In addition to the Wartsila units, Unit 15 can also burn propane to generate electricity.”
Hedrington said Units 14 and 15 were used Monday night to begin restoring service.
“We anticipate having Unit 25 back from its scheduled maintenance by midday Tuesday, which will add a significant layer of reliability and stability to the Harley plant,” he said.
Executive Director Lawrence J. Kupfer apologized to the community for the inconvenience caused by the outages of Sunday and Monday.
“As we have previously indicated, our preference is not to dispatch Unit 26 until its performance and reliability improves. Over the last few days, however, without some of the other units, we had few options other than to add Unit 26 to the dispatch, and unfortunately, its performance indicates there is more work to be done on it.”
Editor’s note: This story updates an earlier story announcing the district-wide power outage.