Turbine’s High Temperature Triggered Tuesday STT Power Outage

Randolph Harley Power Plant

A generating unit’s high temperature triggered a district-wide power outage on St. Thomas on Tuesday, according to the Water and Power Authority.

Generating Unit 25’s protection control system detected high temperature at the power turbine. The unit performed as expected, by shutting down, to avoid extensive damage, WAPA officials said in a statement.

WAPA Chief Operating Officer of Electric Systems Clinton T. Hedrington, Jr. said Wednesday the high temperature indication, caused by a water injection pump failure, triggered the shutdown of the unit which resulted in the loss of Unit 26.

“Unit 26’s new fuel regulating valve performance has improved but the generator’s response to grid swings and surges is still not quite where it needs to be. Unit 23, a WAPA-owned generator, was recently returned to service and will be dispatched more frequently until additional adjustments on Unit 26 are completed, and the unit is proven reliable,” Hedrington said.

At the time of the outage, WAPA’s three propane-fired Wartsila generators were online, as were Units 25 and 26, a pair of rental units that utilize Number 2 oil (diesel) to generate electricity. The combined five units were generating more than 51 megawatts of electricity.

WAPA Executive Director Lawrence J. Kupfer said that in 2020, WAPA will use federal funding to purchase and install an additional 40 megawatts of propane-fired generation to the Harley power plant to provide more efficiently-produced, lower cost, and reliable electric service to its customers.

“The next step in this process occurs later this week when WAPA receives bid packages in response to a previously-issued Request for Proposals for the expanded generation capacity. WAPA’s efforts continue each day to build a more reliable, affordable, and efficient electric system for the Virgin Islands.”

This is the first major St. Thomas outage since a series of severe outages earlier this summer, which WAPA officials believed were largely resolved by replacing fuel regulator valves.