PJM has observed decreased benefits from large amounts of RegD resources providing regulation service. RegD resource participation percentages have at times provided up to 70% of the total effective MWs of regulation and on average RegD percentages have been above 42% of the total effective MW requirement. PJM’s current regulation requirement is 700 Effective MWs on-peak and 525 Effective MWs off-peak.
Similarly, PJM has observed frequent hours when the marginal benefits factor in less than 1. During the commitment phase, the benefits factor defines the benefit and point of diminishing return for RegD resources. The point at which the benefits factor is 1, RegD and RegA resources are providing equivalent benefit to the system. The point of diminishing return, when RegD resources are less beneficial than RegA resources, is when the benefits factor goes from 1 to 0.
Additional challenges to managing system control can occur during times when there is a large percentage of RegD MWs providing regulation. This issue is caused by the RegD control signal moving in the opposite control direction than desired by dispatch. The reason for this is that the RegD signal is programmed to integrate to zero to accommodate the state of charge for energy-limited resources participating in the Regulation Market. The inherent feature of the RegD signal does not allow for sustainability at a given set point.