Integer startup and shutdown variables?
While testing the unit startup and shutdown trajectories with multiple sub-units using the directOnMIP and lambdaXX approximations, I noticed that occasionally the model would start a non-integer number of units, and then round the v_online to an integer on the time step the unit becomes online using the v_shutdown variable. Presumably, the model gains some advantage while ramping if it does this, but I don't know for certain.
Nevertheless, in order to avoid this behavior, it might be necessary to separate the v_startup and v_shutdown variables intoLP and MIP variants similar to v_online. Potentially, another solution might be to change the current logic of when a unit is considered to be online (only when it operates at or above min load) to cover for the duration during the trajectories as well.