PJM, the country’s biggest grid operator, has filed a plan for remaking its capacity markets. The plan would put state-subsidized wind, solar or nuclear power plants in a separate class from other resources to meet the terms of a controversial Federal Energy Regulatory Commission order from June. PJM’s plan is drawing fire from clean energy advocates who say it will increase energy costs by billions of dollars a year in payments to uncompetitive and redundant fossil-fuel-fired power plants.