The Lake Chelan Hydroelectric Project was originally built in 1928 with two 30 MW vertical-shaft Francis turbine generating units. Equipment age and condition of the generating equipment, and lower than expected operating efficiencies, led Public Utility District No. 1 of Chelan County (District) to retain MWH as part of an integrated team to undertake a comprehensive modernization program.
Studies and analysis from the late 1990’s through 2003 identified the objectives for modernization to include:
Unusual water passages and lower than expected efficiencies drove the District to invest time and money into model testing to ensure effective modernization efforts. Construction and testing of a physical model, while not typical for units and plants of this size, proved to be beneficial to verify that desired performance goals would be achieved, before any equipment fabrication began, reducing project risk. Model development and testing (both computer and physical) was performed by Alstom at their hydraulic laboratory in Grenoble, France.
The modernization program included replacements and improvements to the turbines, generators and unit and plant controls. In addition to replacement of most of the major turbine components, generator stators were replaced with new stators rated to accommodate increased turbine capacity. Additionally, the unit and plant controls were replaced with modern digital controls to provide automation and improved monitoring, which led to reduced O&M costs.
The project was completed in 2011. Increased revenue as a result of turbine performance gains essentially financed the entire modernization program.
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