Expert controls replace legacies, 3% boost
Tighter system integration and new controls at the 10th largest U.S. power plant improved load ramp rates by 3% and better regulated temperature. Emerson Process Management said that its Power & Water Solutions group is replacing legacy controls in all four units of Progress Energy Inc.
Tighter system integration and new controls at the 10thlargest U.S. power plant improved load ramp rates by 3% and better regulated temperature. Emerson Process Management said that its Power & Water Solutions group is replacing legacy controls in all four units of Progress Energy Inc.'s (PE) 2,462 MW steam-plant in Roxboro, NC, with Emerson's Ovation expert-control system. The multi-year project began in early 2005, with installation of Unit 2 controls, continuing as controls are installed in the plant's remaining three units. It's part of PE's move to a centralized, integrated control strategy for Roxboro.
Although in place only a few months, coordinated controls reportedly have helped Unit-2's load ramp-rates improve from 91% in 2004 to 94% through November 2005. Additionally, tighter control strategies have helped to improve Unit 2's superheat temperature regulation byoF during load ramps.
Old unit-control systems were at maximum capacity, precluding addition of new controls for selective-catalytic reduction (SCR) and scrubber systems. Now Unit 2 has started-up a recently added SCR system along with the plant controls. Moreover, a flue-gas desulphurization system, using FOUNDATION fieldbus, will also link to the new controls.
The new, integrated control system replaces distributed control systems (DCS) that were data-linked to numerous PLC-based plant systems. DCSs and PLCs used Genius I/O blocks encompassing over 20,000 remote I/O points. Due to a tight outage schedule and added costs, it was not feasible to replace existing Genius I/O with new modules.
Migrating controls for the four-unit plant posed a number of challenges, including:
Supplying reliable and affordable redundant interfaces to the station's 2,700 Genius I/O blocks;
Furnishing operators with a centralized coordinated system to enhance plant operation;
System installation within a 30-day outage schedule; and
Providing flexibility for adding new plant controls.