def min_power_rule(mod, g, tmp):
    """
    **Constraint Name**: GenVar_Min_Power_Constraint
    **Enforced Over**: GEN_VAR_OPR_TMPS

    Power provision minus downward services cannot be less than zero.
    """
    return (
        mod.GenVar_Provide_Power_MW[g, tmp] - mod.GenVar_Downwards_Reserves_MW[g, tmp]
        >= 0
    )