Metso modernizes power plant automation for Xcel Energy

The multiphased automation project in Becker, Minnesota, USA will span six years.

Metso to modernize power plant automation at Xcel Energy, Minnesota, USA Metso will modernize the automation systems at Xcel Energy's Sherburne County Generating Plant in Becker, Minn., USA. This is the first phase of a multiphased renewal project that will span six years. The work, done in stages, will coincide with major plant outages and not impair the plant's long-term 95% availability factor.

Phase No. 1, now underway, includes modernization of the workstations used by operators and engineers to control the unit, data historian computers, communication networks to Metso I/O and data links to foreign sub-systems. It is scheduled to be completed in 2012 and 2013. The follow-on phases, including the modernization of distributed controllers and subsequent I/O replacement, will extend into 2017.

Sherco's three units, which are fueled by low-sulfur western coal from mines in Montana and Wyoming, have a combined generating capacity 2,400 megawatts. The automation systems being modernized are located in Units 1 and 2, and include combustion controls for two drum-based boilers, controls for flue gas desulfurization, scrubber make-up water, and data acquisition.

Metso's first delivery in the Phase No. 1 will cover new automation system hardware and software, including workstations for operators and engineers, process management tools, an OSI-PI link, links to a third-party optimization software, a link to Xcel Energy's generation dispatch center and links to PLCs throughout the plant. Metso will also participate in rebalancing the load on the plant control networks.

The modernized automation system will provide the plant with the opportunity to make intelligent choices when replacing aging plant assets. For example, when old electric drive units controlling dampers and valves with slide-wire and limit switch feedback are replaced, modern smart drive units can be installed. Smart drive units coupled to the automation system provide valuable feedback on position, drive temperature, torque and other critical parameters that allow not just precise control, but early warning diagnostic information such as damper jams, or other minor problems that could lead to a unit trip if undetected.