Ancillary Services Market

Ancillary services help balance the transmission system as it moves electricity from generating sources to ultimate consumers. PJM operates two markets for ancillary services: the Synchronized Reserve Market and the Regulation Market.

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Synchronized Reserve supplies electricity if the grid has an unexpected need for more power on short notice – such as unplanned generator outages or unexpected spikes in energy demand. Think of synchronized reserve as a spare tire – a backup in case of an emergency. The power output of generating units supplying synchronized reserve can be increased quickly to supply the needed energy to balance supply and demand.

In addition to Synchronized Reserve and Regulation services, Black Start Service supplies electricity for system restoration in the unlikely event that the entire grid would lose power.

Regulation is a service that corrects for short-term changes in electricity use that might affect the stability of the power system. It helps match generation and demand and adjusts generation output to maintain the desired electrical frequency for the grid to function normally. Devices such as hot water heaters and plug-in hybrid electric vehicles can respond to the PJM frequency regulation signal and act as demand-side regulating resources. Learn more in the Energy Innovations section.

This image illustrates the fluctuations in energy use that can happen in a matter of seconds. Regulation helps stabilize the system instantaneously to balance this supply and demand mismatch. *This is a conceptual image only and not an actual representation of how any particular generator follows the regulation signal.