IMM recommends that MISO evaluate the feasibility of solving the day-ahead market with 15-minute scheduling intervals. As initially designed, due to technological limitations, the day-ahead market software did not permit market solutions on a basis as frequent as the real-time dispatch solutions. The granularity mismatch creates significant operational drawbacks.
By producing hourly schedules based on 60-minutes of ramp capability and hourly load forecasts, the day-ahead schedules cannot track the expected changes in real-time system needs, particularly during ramping periods. It also regularly results in generator schedule changes from hour to hour that are not feasible, which results in substantial make-whole payments. More granular day-ahead market schedules would lower these uplift costs and better prepare the system to respond to the real-time needs.