It’s a digital world, and even aging power plants are experiencing the benefits of digital controls technologies. The following cover stories provide insight into the latest options and inspiration for your own plant controls projects.

The editors of POWER have spent the past few months working with industry experts and ISA POWID (see sidebar) to bring you this special cover story series on advanced digital controls. Each article was selected for its unique perspective and helpful solutions to the digital control issues facing the power generation industry. Though each segment of the industry has its own peculiar challenges, many advancements should spill over, say, from the nuclear side of the industry to the fossil segment.

You might be surprised by the attention to nuclear plants, given that watching the race to construct new nuclear plants in the U.S. is like watching molasses flow in January in Duluth. However, the nuclear industry as a whole is anything but stagnant. It continues to perform at a very high level in every important performance category while maintaining an excellent safety record with ever-shorter refueling outages. For example, nuclear energy production from the 104 operating U.S. plants is expected to remain above 800 million MWh for the third straight year in 2009, compared with 109 nuclear plants that produced 527 million MWh in 1988.

This dramatic leap in plant performance can be attributed to improved plant management, advances in technology that translate into improved operation and maintenance practices, and an industry that openly shares best practices (see POWER, Nov. 2009, "Benchmarking Nuclear Plant Production Costs").

Another reason is the nuclear industry’s commitment to upgrading original analog or first-generation digital controls to the latest in digital controls technology. Advances in controls technology have also been a key enabler of the industry’s rapid pace of increasing plant ratings. Since 1977, the Nuclear Regulatory Commission has approved some 124 nuclear plant uprates, representing about 5,640 MW of added capacity. These uprates, coupled with improved plant availability over the past two decades, have added the equivalent of over a dozen new nuclear plants.

Nuclear plants are not the only ones being revitalized with digital controls. Many coal-fired plants are finding that a digital control upgrade must be included as part of any emissions upgrade project in order for the entire plant to achieve expected low emissions guarantees. (We are indeed fortunate that prevention of significant deterioration permits aren’t violated when analog controls are upgraded to digital.) Early gas-fired combined-cycle plants are also undergoing upgrades to new digital controls because even the minute efficiency and operating flexibility provided by the upgrades are economic.

—Dr. Robert Peltier, PE is editor-in-chief of POWER