Hydroelectric plant in Hawaii upgrades control system

Century-old Kauai Coffee plant moves from mechanical into digital age installing GE Energy control platform, increasing output and reducing maintenance.


The hydroelectric plant had been operating with its original flyball governor with its associated problems.

On the north shore of Kauai, the Kauai Coffee Co . has been operating Hawaii's first hydroelectric plant, still running two 1906-era Pelton hydro turbines, complete with their mechanical fly-ball governors. Far from a museum piece, the company depends on the Wainiha plant to provide clean reliable energy, so the modernization was critical. Working with GE Energy , Kauai Coffee installed a new Mark VIe digital control platform and new hydraulic system.

"The new digital control system and its ToolboxST software tools are more accurate and dependable, easier to maintain, and-best of all-more efficient, allowing additional kilowatt hours of electricity to be generated each year," explains Kauai Coffee Company's project manager Dan Sargent. "The system and software ushers in a new era of power generation for this valuable company asset."

The original 25 Hz generators were used to power irrigation pumps on the dry side of the island for sugarcane irrigation until GE converted them to 60 Hz generators in 1929 for connection to the electrical grid. Maintaining the 100-year-old governors to run efficiently and correctly was difficult, with malfunctions resulting in costly repairs and downtime. Using its experience with hydroelectric plants, GE Energy partnered with Kauai Coffee's experienced and skilled team to overcome these control challenges.

The new control system brings the century-old plant into the digital age.
The entire harmonics and operation of the installation have now changed. Legacy controls on the dual needle impulse turbines created an imbalance on needle position that resulted in lost efficiency and continuous vibration and wear. The new control system achieved accurate balancing of the needles, which resulted in increased power production during lower water levels, less parasitic power consumption, and smoother operation.

Start-up time for the plant decreased from an average of four hours to less than 10 minutes. The Wainiha plant staff also benefits from the ability to monitor and troubleshoot its system in real-time, both on-site and remotely, contributing to plant productivity, maintainability, and ease of operator training.

"This project highlights GE's continued service support of the hydropower segment," says Brian Palmer, vice president, optimization and control, GE Energy . "Our solutions can deliver increased efficiency and productivity for the installed base of hydro power plants around the world."

Upgrading this plant is part of Hawaii's efforts to implement a progressive clean energy initiative. As part of a bill signed into law on June 25, 2009, utilities must generate 40% of their electricity from renewable sources by 2030. The Wainiha station generates 4 MW, enough power to supply its coffee processing factory, visitor center complex, and main offices, while also producing 6% of the island's total power generation.

Hawaii's natural power-generating resources are primarily hydro, wind, and geothermal, with other energy sources such as liquid fuels, gas, and coal imported at high cost. With more than 40 ft. of rain per year, Mt. Waialeale provides a reliable supply of water and helps ensure that this project will provide consistent hydropower to help offset the rising costs of generating power from imported fuel.

-Edited by Peter Welander, process industries editor, PWelander@cfemedia.com
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