By installing Emerson’s Ovation technology at its Redbud combined-cycle power plant, Oklahoma Gas and Electric (OG&E) gained the ability to cold start each unit 25 to 35 minutes faster. Located in Luther, Oklahoma, the Redbud plant comprises four identical 1 X 1 units generating a combined output of 1,230 megawatts. The plant began commercial operation in 2003 outfitted with controls from nine different vendors. This patchwork of control systems presented numerous challenges.
“We recognized the inefficiencies inherent in utilizing multiple different control systems. We wanted to consolidate to a standard automation platform to improve reliability and consistency across all units,” said OG&E’s Khoa Le, project manager for the controls upgrade.
Emerson replaced the steam turbine controls as well as static excitation and vibration monitoring systems with an integrated Ovation solution. In addition, Emerson performed steam turbine mechanical retrofits to eliminate single points of failure and provide faster response. With the upgraded and tuned steam turbine controls, along with the redundant mechanical design, the turbines can reach setpoint quicker, reducing cold start times by 25-35 minutes per unit.
Emerson also replaced heat recovery steam generator and balance-of-plant controls at each unit and integrated the auxiliary boiler, water treatment, effluent de-ionization and duct burner controls into the Ovation system. Tied together on a single network, each unit’s Ovation system interfaces with OEM combustion turbine controls for supervisory monitoring and control.
Previously, plant personnel had to monitor multiple process and alarm screens from different vendors. By paring down thousands of control sheets to hundreds and implementing consistent logic, graphics and alarm philosophies across the entire plant, greater visibility was gained into plant processes. Work for all four units was completed during a 16-week outage.