A procedure to specify the weighting matrices for an optimal load-frequency controller

摘要

The linear quadratic optimal regulator is one of the mostpowerful techniques for designing multivariable control systems. Theperformance of the system is specified in terms of a cost, which isthe integral of a weighted quadratic function of the system state andcontrol inputs, that is to be minimized by the optimal controller. Thecomponents of the state cost weighting matrix, Q, and the control costweighting matrix, R, are ours to choose in mathematically specifyingthe way we wish the system to perform. Changing these matrices, wecan modify the transient behavior of the closed-loop system. Thispaper addresses the stabilization and performance of theload-frequency controller by using the theory of the optimalcontrol. A new technique, based on pole placement using optimalregulators, to overcome the difficulties of specifying weightingmatrices Q and R is proposed. The design method employs successiveshifting of either a real pole or a pair of complex conjugate poles ata time. The proposed technique builds Q and R in such a way that thesystem response also obeys conventional criteria for the system polelocation. The effectiveness of the proposed method is illustrated bynumerical examples.