The board that oversees the reliability of the high-voltage power system in 13 Northeast and Midwest states has authorized $1.5 billion in construction projects to strengthen the power grid.

The approvals include several large and midsize projects that address reliability issues in multiple areas, regional transmission group PJM Interconnection LLC said on Feb. 15.

Projects valued at $918 million are in the transmission zone of Public Service Electric and Gas, in New Jersey.

The largest project addresses aging infrastructure and requires the rebuilding of existing transmission lines in three counties south of Newark. The three-phase, $740-million project includes upgrading 138-kV circuits to 230-kV. The project is set to start at the end of this year or early next year, with new tower construction expected to begin in summer or fall 2018. The scope includes the replacement of equipment, some of which date to the 1920s, PJM said.

An additional $39 million in projects is located in the Midwest. About $326 million in upgrades were approved for the Dominion Energy transmission zone in Virginia and North Carolina, which includes the $225-million reconstruction of a portion of the 500-kV Mt. Storm line.

The Virginia-based utility plans to remove and replace the existing steel lattice towers, which were built before 1966, and upgrade existing conductors with modern equipment. The upgrades are expected to increase the capacity of the line by about 66%, Dominion said.

Projects in PJM's western portion, in the American Electric Power transmission zone, total $133 million and include the construction of new substations and upgrading circuits to increase capacity.

"The growing need to replace aging infrastructure, [increase] energy efficiency and the resulting reduction in the growth of demand for electricity are affecting transmission development,” said Andrew Ott, PJM president and CEO. The current approvals reflect that trend, he noted.

PJM’s territory includes transmission in Delaware, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia and the District of Columbia.