Duke Energy Carolinas on Monday asked regulators for permission to raise its North Carolina rates by 9.7 percent, increasing typical residential bills by about $14 a month.

The increase would be the Charlotte-based utility’s third since 2009. The $446 million in new annual revenue would help pay for two new power plants and upgrades to two nuclear plants, among other capital expenses.

Duke Energy Carolinas serves 1.9 million customers, about 10 percent of which are in Durham, Chapel Hill and the western Triangle. Duke’s rates and the rates of its subsidiary, Progress Energy, are independent of each other. Progress has a separate rate case before the N.C. Utilities Commission.

Duke’s request to the Utilities Commission would raise residential rates 11.8 percent, increasing typical monthly bills from about $103 to about $117. Commercial rates would go up 9.6 percent and industrial rates 5.3 percent.

In January 2012 the commission allowed Duke to raise rates 7.2 percent, the largest increase in more than 20 years. In 2009, rates rose 7 percent over two years.

The latest request is likely to prompt a consumer backlash as the ailing economy slowly recovers.

Consumer groups, including the powerful AARP, are already gearing up to fight a rate hike.

Hundreds of comments from people opposing the 2012 rate hike flooded the commission, and hundreds more spoke at public hearings.

N.C. Attorney General Roy Cooper appealed that increase, which hiked residential bills about $7 a month, to North Carolina’s Supreme Court. Cooper argues that the utilities commission didn’t fully assess impacts on low-income customers. The court has not yet ruled.

Duke says the higher rates will pay for power plants with fewer air emissions. Those include the Dan River plant in Eden, which is fueled by cleaner-burning natural gas, and a new unit at its Cliffside coal-fired plant in Rutherford County that has state-of-the-art pollution controls.

The Oconee and McGuire nuclear plants also got upgrades that the higher rates would pay for.

Henderson: 704-358-5051 Twitter: @bhender