OREANDA-NEWS. The PJM Interconnection is proposing a plan to reduce the voltage swings and other reliability issues caused by wind generators that it worries could become increasingly hard to manage as that resource grows.

The plan could address a frequent criticism that renewable resources fail to provide the same reliability benefits as the baseload generators they are replacing. Those large-scale plants operate in synch with the alternating current of the grid, providing "reactive" power which is the component of power needed to support voltage and frequency.

Renewable resources in contrast are not synchronized with the grid and instead "push" energy onto the grid using inverters that typically do not provide reactive power. Legacy plants provide enough reactive power now, but PJM worries this could change as they are displaced by growing amounts of renewables.

The grid expects renewable capacity to grow to 15,000MW next year, which is nearly twice the renewable capacity it had seven years ago. PJM has interconnection requests for 25,000MW more renewable capacity, of which 20,500MW would come from wind.

PJM's plan to deal with this potential reliability issue is to require new wind and all other new non-synchronous resources to install "enhanced inverters" that would be able to provide reactive power and help mitigate voltage swings. The grid says this equipment is now commercially available and has the added benefit of letting renewables "ride through" disturbances without tripping offline.

PJM last week asked the Federal Energy Regulatory Commission to require enhanced inverters for all future interconnections with non-synchronous resources. The grid said requiring inverters to provide reactive support would add "little, if any" incremental costs and noted that the wind industry is already manufacturing turbines with "baked-in" reactive support.

The grid has asked the tariff changes to take effect by 1 May to coincide with the start of its next interconnection services queue.