A method for monitoring and control of an oil or gas production system, or part(s) thereof, which has one or more processing unit(s), flow line(s) and process control means, the method comprising: - providing an interacting feedback control system comprising an Inflow Estimator module and at least one of an Outflow Smoothening module, an Overload Avoidance module and a Ramp Up module, - making the modules functional through algorithms based on dynamic or steady state components for generating output signals by processing of input signals, - integrating the modules so as to co-operate or interact with each other in any combination comprising two or more of the modules, - arranging and operating the Inflow Estimator module for generating dynamic estimates (63,64) of gas or liquid inflow flow rates based on measurements (43,44,45,47,49) of at least one of a set of process variables associated with said processing unit(s) or flow line(s), including: level, pressure, flow rate, temperature or load, - arranging and operating the Outflow Smoothening module for mitigating flow rate variations throughout the production system by utilizing available buffer capacity in the production system, - arranging and operating the Overload Avoidance module for avoiding overloading of the production system by keeping a load indicator non-positive or as close to zero as possible, - arranging and operating the Ramp Up module for automatically ramping up the throughput of the production system by tracking a ramp-up curve based on flow rate set points and/or pressure set points, - wherein the Outflow Smoothening module, the Overload Avoidance module and the Ramp Up module are configured and operated for calculating setting(s), i.e. value(s) of set point(s) for said process control means associated with at least one controlled variable in form of said measured or estimated level, pressure, flow rate, temperature or load, including compensating for nonlinearities of said process control means. - providing an interacting feedback control system comprising an Inflow Estimator module and at least one of an Outflow Smoothening module, an Overload Avoidance module and a Ramp Up module, - making the modules functional through algorithms based on dynamic or steady state components for generating output signals by processing of input signals, - integrating the modules so as to co-operate or interact with each other in any combination comprising two or more of the modules, - arranging and operating the Inflow Estimator module for generating dynamic estimates (63,64) of gas or liquid inflow flow rates based on measurements (43,44,45,47,49) of at least one of a set of process variables associated with said processing unit(s) or flow line(s), including: level, pressure, flow rate, temperature or load, - arranging and operating the Outflow Smoothening module for mitigating flow rate variations throughout the production system by utilizing available buffer capacity in the production system, - arranging and operating the Overload Avoidance module for avoiding overloading of the production system by keeping a load indicator non-positive or as close to zero as possible, - arranging and operating the Ramp Up module for automatically ramping up the throughput of the production system by tracking a ramp-up curve based on flow rate set points and/or pressure set points, - wherein the Outflow Smoothening module, the Overload Avoidance module and the Ramp Up module are configured and operated for calculating setting(s), i.e. value(s) of set point(s) for said process control means associated with at least one controlled variable in form of said measured or estimated level, pressure, flow rate, temperature or load, including compensating for nonlinearities of said process control means.