A overhaul design approach that helped this plant excel

Lake Chelan Hydro Modernization Project

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 Stantec as part of an integrated team to undertake a comprehensive modernization program.

Studies and analysis identified the objectives for modernization to include extending the service life of the generating equipment an additional 40 years, maximizing energy production, and eliminating periodic “wear and tear” repairs required by the aging equipment.

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) were 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.

Services provided engineering and design services, turbine design development in collaboration with Alstom and the district, and developed technical specifications and contractual requirements for equipment suppliers.

Our team was successful in increasing the service life of the facility by 40 years, increasing peak turbine efficiency, shifting output to 5 MW higher, reducing the number of repairs needed, and reducing the environmental impact of the plant. Our team also helped reduce costs and the increased revenue because of turbine performance gains essentially financed the entire modernization program. This project was awarded the 2012 Gold Award for Complexity by the American Council of Engineering Companies (ACEC) of Washington.