Federal agencies join forces to bring Little Goose Dam back online

arrowBack to Newsroom

Federal agencies join forces to bring Little Goose Dam back online

October 11, 2024

Above is the recently acquired motor-operated disconnect switch that will connect Little Goose generation to the grid.

Cross-agency collaboration minimized the disruption of equipment failure, allowing the dam to resume its vital role of power generation and water management for the Pacific Northwest.

Through the joint effort of multiple federal agencies, Little Goose Dam was restored to operation following the failure of a crucial piece of equipment. The agencies' collaboration minimized the disruption, allowing the dam to resume its vital role of power generation and water management for the Pacific Northwest.

On the morning of June 14, operators at the U.S. Army Corps of Engineers, Walla Walla District
(USACE) discovered that electrical arcing had severely damaged the motor-operated disconnect switch that connects electricity produced by the dam to the grid.

Arcing occurs when a loose electrical connection between conductors forces the current through air gaps, melting the conductors as a result. On high-voltage lines, the arc can reach temperatures as high as 35,000 degrees Fahrenheit, which is significantly hotter than the surface of the sun.

The motor-operated disconnect switch (MOD) plays an important role in the operation of Little Goose Dam, operating as a 14-foot-long motorized light switch that connects two electrical systems. It allows or prevents the flow of electricity, according to Bill Dull, the Walla Walla District reliability program manager.

"The operational significance of the MOD cannot be overstated," said Dull. "This device connects Little Goose's electric power to the 500-kilovolt transmission line; its failure forced four of the six generating units offline."

Little Goose, which lies on the lower Snake River, has a total generating capacity of 930 megawatts, with each generating unit rated at 155 MW. When a unit goes offline, water that would normally flow through a turbine to produce electricity is released over the dam spillway instead. This is particularly unfortunate timing, as the Columbia River Basin is experiencing a below-average water year due to lower snowmelt in the Cascades.

Recognizing the impact of a damaged MOD, USACE maintenance crews responded quickly to assess the extent of the damage and find a workable solution.

Dull contacted Rod Morris, who works in BPA's Customer Service Engineering Department, to request technical assistance and see if BPA had a spare MOD unit in reserve. After confirming that BPA did not have a spare, Morris leveraged his extensive network of contacts to locate one. "I wasn't sure if we would be successful locating the unit, as it is no longer in production," he said.

Morris quickly began reaching out to different power utilities and federal partners to locate the discontinued MOD switch. He discovered that the Western Area Power Administration's Sierra Nevada Region will be replacing three of the same model MODs on their system later this year. After discussion between the three parties, WAPA agreed to transfer ownership of the units to the USACE. The equipment delivery is expected in November.

In the meantime, BPA sent a repair crew to Little Goose to assist USACE in implementing an interim solution while the MOD replacement search was underway. The joint team worked tirelessly to install a spare jumper that bypassed the damaged disconnect switch, allowing power to flow from the generating units back onto the transmission system. On June 18 at 9:38 p.m., Little Goose was fully back online.

When temperatures rise in the spring and summer months, the electric output of the federal hydropower system becomes increasingly important to the region. The USACE estimates that during the three-day outage, approximately 7,000 megawatt hours of power was lost due to the units not producing energy. This is enough electricity to supply more than 7,500 homes in the region for a month.

The coordination and collaboration demonstrated by the numerous teams across each agency is remarkable. This accomplishment involved dozens of individuals, including line workers, substation operators, fish biologists, electrical engineers and many more, all working together with a goal of bringing Little Goose Dam back online. Team members recognized the impact of loss power generation to the region.

During prolonged generation outages, sometimes BPA must purchase power from the energy market to meet its demand. More power purchases can increase power rates for BPA's core customer base, so minimizing the outage duration was a priority for both agencies.

"It truly was a pleasure working with Rod and the rest of the BPA crew," said Dull. "The collaboration between USACE, BPA and WAPA-SNR reflects effective multi-agency cooperation with the goal of solving difficult problems in a time of need."

Tags

social_facebook Share social_twitter Tweet email Email print Print