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Orchestrating Outages

IT systems ease the pain of power plant restarts.

Fortnightly Magazine - July 2012

DCS migration projects to validate new control systems for startup and train plant personnel.

In one example, Intermountain Power used an Invensys simulator to support DCS migrations at its 1,300-MW coal-fired plant near Delta, Utah.

The outage included a four-week window in which to install and validate the new DCS and then re-start the plant. Management opted for DCS simulator testing because even minor control system errors could delay unit start-up and subsequently the plant’s return to service. In extreme cases, control system errors could cause catastrophic equipment damage.

Operator error was a concern as well, especially since Intermountain opted to remove the entire control panel and install a new CRT-based DCS—all of which presented a potential challenge to operators accustomed to the look and feel of the old system. With potential lost generation revenues in excess of $1 million per day, management decided that avoiding a day or two of unplanned outage time would more than justify the cost of the simulator, controller validation, and operator training. The plant continues to use the simulator for new operator training and to test proposed control system changes before they’re actually implemented at the plant.

Invensys reports similar results at the 720-MW Keadby gas-fired combined-cycle plant at Scunthorpe, North Lincolnshire in the UK. DCS software integration issues were uncovered and resolved before the system was accepted for installation—smoothing the installation process.

Nuclear Restart

Of course, when it comes to outage management, the nuclear power industry essentially wrote the book. In the last 30 years the industry has cut standard outage times by nearly 50 percent. But with most plants now well over 30 years of age, staying within the planned outage timeline isn’t always easy.

“From the industry’s perspective the shorter the outage, the better,” says George Beam, vice president of installed base at Areva NP. “In the 1980s and ’90s, [utility plant] outages were typically 50 to 60 days. Then in the late 1990s some plants were sold and operated in deregulated markets, and the perspective on outages began to change. Now everybody’s shooting for 25 days. For some refueling outages, it’s 18 to 20 days.” At older plants, outages can go up to 45 days, he says.

Competition among generators drove outage times downward, and the same forces are still at work in wholesale markets.

“The sooner a plant is back on-line, the sooner it’s selling 100 percent power, 24/7,” Beam says. “And that’s key because in today’s markets, 100 percent isn’t as profitable as it once was. Due to low natural gas prices, these plants are no longer the geese that lay the golden eggs. It’s not just the coal plants—natural gas prices are impacting nuclear units too.”

In addition to the timetable, Beam says nuclear customers especially are concerned with outage productivity—who can do the most work in the shortest amount of time, while also limiting worker radiation exposure. That, in turn, has spurred new automation processes and technology developments. To reduce exposures, Areva employs an application robot that can perform a variety of outage tasks. Video equipment allows the