def min_power_rule(mod, g, tmp):
    """
    **Constraint Name**: GenAlwaysOn_Min_Power_Constraint
    **Enforced Over**: GEN_ALWAYS_ON_OPR_TMPS

    Power minus downward services cannot be below a minimum stable level.
    """
    return (
        mod.GenAlwaysOn_Gross_Power_MW[g, tmp]
        - mod.GenAlwaysOn_Downwards_Reserves_MW[g, tmp]
        >= mod.Capacity_MW[g, mod.period[tmp]]
        * mod.Availability_Derate[g, tmp]
        * mod.gen_always_on_min_stable_level_fraction[g]
    )