Mechanical Engineering
Duke Power Hydro System Rehabilitation and Upgrade Program
In response to an increased frequency of hydro equipment failures and unplanned outages, Duke Energy completed a comprehensive, systematic evaluation of its hydroelectric system, which revealed the need for a rehabilitation and upgrade program. A prioritized total station upgrade approach was adopted. The program focuses on rehabilitation and upgrade measures to improve operations at specific plants, while maximizing the value of hydroelectric resources within the corporation’s generation operations.
Upgrades have been completed or are underway at seven pre-1930 hydro stations: Lookout Shoals (27.8 MW), Dearborn (42 MW), Wateree (85 MW), Wylie (68 MW), Fishing Creek (44 MW), Oxford (42 MW) and Cedar Creek (45 MW). Detailed engineering is underway for similar modifications at Jocassee Pumped Storage Station, and program evaluation is ongoing for three more stations.
Devine Tarbell & Associates, Inc’s (DTA) staff performed all engineering activities associated with the upgrade program from initial condition assessments and progress through work scope development, cost estimates, economic analyses, detailed engineering and field engineering support during implementation.
DTA staff provided mechanical engineering support for the evaluation of various options to address dissolved oxygen enhancement and continuous minimum flow requirements. DTA’s staff also performed economic and technical feasibility studies, developed project work scopes, prepared vendor procurement specifications and vendor bid evaluations, coordinated vendor drawing review, and completed engineering and design for mechanical auxiliary system upgrade. Turbine upgrades included complete turbine overhauls (including the use of synthetic substitutes for lignum vitae turbine guide bearings and greaseless bushing bearings in certain cases).
Mechanical auxiliary systems were upgraded and designed to allow unmanning of the stations. Governor oil systems were converted from low-pressure to high-pressure hydraulics, and feature unitized hydraulic power units designed to interface with new digital electronic governors and control systems. Cooling water system upgrades included new pumps, self-cleaning strainers, centrifugal separators or back-flushable filters to minimize suspended solids from the silt laden raw river water; flow control valves to ensure a consistent supply of clean water for cooling; turbine guide bearing lubrication; and new corrosion resistant piping. Upgrades were also completed to the bearing lube oil systems and the compressed air system.