The temporary relaxation of constraints permits the efficient and cost-effective operation of certain process models. Ramp imbalances are controlled using soft-landing constraints. Such soft-landing constraints permit a smooth return to a ramp limit which permits continued operation of a system, such as a petrochemical system that includes several inflows and outflows, as opposed to a forced shut-down of the system. A ramp imbalance may be controlled by determining imbalance ramp rates and imbalance set-point ramp rates and using those constraints to resolve the dynamic control problem of a process model.