Combination of measurements as controlled variables for self-optimizing control

A new method for selecting controlled variables (c) as linear combination of measurements (y) is proposed based on the idea of self-optimizing control. The objective is to find controlled variables, such that a constant setpoint policy leads to near optimal operation in the presence of low frequency disturbances (d). We propose to combine as many measurements as there are unconstrained degrees of freedom (inputs, u) and major disturbances such that Deltac(opt) (d) = 0. To illustrate the ideas a gas-lift allocation example is included. The example show that the method proposed here give controlled variables with good self-optimizing properties.