def power_provision_rule(mod, g, tmp):
    """
    Power provision for must run generators is simply their capacity in all
    timepoints when they are operational minus any auxiliary power consumption.
    """
    return mod.Capacity_MW[g, mod.period[tmp]] \
        * mod.Availability_Derate[g, tmp] \
        * (1 - mod.gen_must_run_aux_consumption_frac_capacity[g])