Quadratic Optimal Feedback Research Articles

Active Pitch Control in Larger Scale Fixed Speed Horizontal Axis Wind Turbine Systems Part I: Linear Controller Design

This paper reviews and addresses the principles of linear controller design of the fixed speed wind turbine system in above rated wind speed, using pitch angle control of the blades and applying modern control theory. First, the non-linear equations of the system are built in under some reasonable suppositions. Then, the non-linear equations are linearised at set operating point and digital simulation results are shown in this paper. Finally, a linear quadratic optimal feedback controller is designed and the dynamics of the closed circle system are simulated with digital calculation. The advantages and disadvantages of the assumptions and design method are also discussed. Because of the inherent characteristics of the linear system control theory, the performance of the linear controller is not sufficient for operating wind turbines, as is discussed.

A gradient flow approach for computing jump linear quadratic optimal feedback gains

A class of linear systems subject to sudden jumps in parameter values is considered. To solve this class of stochastic control problem, we try to find the best feedback control law depending both on the measurable output as well as the mode of the system. A gradient flow based algorithm is derived for this problem. It is shown that an optimal solution can be successfully computed by finding the limiting solution of an ordinary differential equation which is given in terms of the gradient flow associated with the cost function. Several important properties are obtained. A numerical example is solved.

A gradient flow approach to computing a non‐linear discrete time quadratic optimal feedback gain matrix

A gradient flow approach to computing a non‐linear discrete time quadratic optimal feedback gain matrix

A gradient flow approach to computing a non-linear discrete time quadratic optimal feedback gain matrix

In this paper we propose an approach to solving infinite planning horizon quadratic optimal regulator problems with linear static state feedback for discrete time systems. The approach is based on solving a sequence of approximate problems constructed by combining a finite horizon problem with an infinite horizon linear problem. A gradient-flow algorithm is derived to solve the approximate problems. As part of this, a new algorithm is derived for computing the gradient of the cost functional, based on a system of difference equations to be solved completely forward in time. Two numerical examples are presented.

Sensitivity reducing observers for optimal feedback control

This paper considers the problem of designing an observer for use in a linear quadratic optimal feedback control scheme so as to minimize the effects of small departures in the plant parameters from their nominal values.