The Randolph Harley Power Plant in St. Thomas, USVI. Photo Credit: ERNICE GILBERT, V.I. CONSORTIUM.
V.I. Water and Power Authority Chief Executive Officer Karl Knight on Monday described the latest St. Thomas/St. John District power disruption as a “power crisis,” but said he did not yet consider it an emergency, even as he outlined the technical failures that forced the Randolph Harley Power Plant offline and left customers facing unstable service and possible two-hour rotations.
Speaking during a Monday morning press conference, Mr. Knight said the districtwide outage that began Saturday evening was caused by a “series of cascading technical issues” that started with Unit 27, long considered one of the more problematic generation units in the St. Thomas plant.
According to Mr. Knight, Unit 27 “tripped offline due to a fuel valve error,” triggering “fluctuations in frequency and voltage that ultimately caused the [Randolph Harley power plant] to go offline.”
Once Unit 27 failed, WAPA’s remaining Wärtsilä engines could not reliably bring the plant back into service. Mr. Knight said the engines operate well when other generation is already online, but are not as effective when they must restart the entire plant and begin carrying system load on their own.
“They run really well when the other generation is already online,” Mr. Knight said. However, “if one of those units has the burden of starting the whole plant and bringing on loads, they're not as effective as the gas turbine.”
WAPA engineers attempted to follow the utility’s established “black start” protocol, the process of restarting a power plant without outside electrical support, using only the Wärtsilä engines. Mr. Knight described that process as “hit or miss,” saying it “really had some challenges” during the latest outage.
By Sunday night, plant personnel returned to Unit 27 in an effort to stabilize the system, but that effort also failed. “Unit 27 at some point last night started shedding load, and so that eventually took the plant out again around 4 o’clock this morning,” he explained.
As of 10:35 a.m. Monday, WAPA said power had been restored to portions of three feeders. However, officials cautioned that “power may not be stable until full generation is brought back online.” Customers were advised that two-hour rotations could be expected if sufficient generation could not be achieved.
The latest outage follows recent efforts by WAPA to strengthen backup generation for St. John and improve the utility’s ability to respond when generation at the Randolph Harley Power Plant is destabilized.
After the last major multi-day outage in the district, Mr. Knight presented WAPA’s board with two plans. The first, which became public in mid-April, involved acquiring five Caterpillar generator units through partnerships with Wagner Power Systems and MacAllister Machinery Company, Inc., with WAPA targeting delivery and commissioning within four to six months.
“These units represent the most expeditious path to delivering emergency power to St. John while continuing ongoing efforts at the Randolph Harley Power Plant,” Mr. Knight said at the time.
A few weeks later, Mr. Knight presented another proposal to source emergency generators capable of producing up to 10 megawatts of power for St. John, which relies completely on electricity supplied from St. Thomas. The goal was to quickly provide backup power for the island.
Board members objected to acquiring lightly used units and directed Mr. Knight to return with a proposal for brand new generators. At the time, the CEO warned that the new-unit option could leave St. John exposed to outages for another year or two.
On Monday, Mr. Knight said WAPA is now “concluding the acquisition of 10 megawatts of generation for standby power on St. John,” in line with that second proposal. The units were tested on May 22 and are now being prepared for shipment from Wisconsin to the U.S. Virgin Islands, he said.
WAPA has already “applied for the permits for the installation of those units once they arrive,” Mr. Knight added.
According to the WAPA CEO, those generators will “avoid future rotations of power on St. John, while reducing the need for rotations on the island of St. Thomas.”
WAPA is also acquiring a 2.5-megawatt turbine to be installed at the St. Thomas power plant. Mr. Knight said the turbine “will assist in future black start situations,” reducing the utility’s reliance on Wärtsilä engines to restart the plant after a shutdown.
Those additions, however, are not immediate solutions. “Realistically, it’s about a 12-month timeframe from purchase to installation, and ultimately permitting and commissioning,” Mr. Knight said.
In the meantime, he said “repairs are going to commence shortly on Unit 15,” while work continues on the acquisition of permanent replacements for both Units 14 and 15.
For the current outage, Mr. Knight said he was “hopeful” that power would be fully restored to the St. Thomas/St. John District “sometime this evening.”
He pushed back, however, against the suggestion that an emergency declaration is currently necessary.
“We have a power crisis this morning,” Mr. Knight said. “If it becomes a prolonged crisis, we perhaps can start to refer to it as an emergency….I know there’s a lot of PTSD from the last round of rotating outages that lasted two and a half weeks. As of this morning, I have no expectation that this will be nearly as prolonged an event.”
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