On the design of stochastic RST controllers based on the generalized minimum variance

This paper presents a general framework based on the RST structure for performing fair comparisons between deterministic and stochastic digital linear controllers. Due to the chosen RST formulation, it can be shown that any linear Single-Input Single-Output controller may be designed as a Generalized Minimum Variance Controller, i.e. as a stochastic controller. This in particular reduces the variance of the control signal and in turn leads to a better output characteristic. The method is applied to the controllers of an exemplary Single-Machine Infinite Bus system, namely the AVR and governor, where it is shown that the voltage and power regulation for the non-stochastic and the GMVC are similar whereas the control signal given by the latter is much smother than for the former, even using the same set of gains for both.