The scope of the project included a retrofit for one of the turbine rotors, as well as the mechanical-hydraulic controls for the 750 MW main steam turbine. The project involved removing the original mechanical governor and retrofitting the wet box actuator and interface to the steam valves, as well as a new overspeed trip system.
In addition to the traditional base speed and load control, the control solution included an automatic turbine start-up program and rotor stress monitoring.
On completion of the Unit 5 turbine retrofit project, the unit ramped up smoothly and adjusted to lower loads than it has with the new ABB turbine controls. ABB has worked closely with the plant operations team at Four Corners for more than two decades leveraging their combined experience in power generation technologies.
We are delighted with the success of this retrofit and pleased with the life extension, energy efficiency and optimization benefits it will bring to the plant, said Kevin McAllister, Head of ABBs Power Generation division in North America.
As part of the Unit 4 order, the scope of work has been enhanced to include the replacement of low pressure pilot valve actuators on the boiler feed-pumps with the final element high pressure actuators supplied by the new hydraulic skid to be installed for the main unit. The existing vibration monitoring system will also be replaced with ABBs turbine vibration monitoring system. Installation and start-up of Unit 4 is scheduled for the spring of 2010.