BACKGROUND INFORMATION

1. Field

The present disclosure relates generally to a feedback control method for control optimization and, more specifically, to an improved application of extremum seeking control.

2. Background

Adaptive control is the method by which a controller must adjust a system that has varying or uncertain parameters. One such method of adaptive control is extremum seeking control (ESC). ESC is used to determine and maintain the extremum value of a function. In most applications, ESC tracks a varying maximum in a performance index and attempts to determine the optimal performance of the control system as it operates. The aim of employing ESC is to design a controller that drives system parameters to their performance-optimizing values, using only output measurements.

The ESC control algorithm has been proposed in the prior art to locate and track the point of optimal efficiency for power maximization in systems related to fluid dynamics. An illustrative example is maximizing power in a wind turbine. The current state-of-the-art applies the ESC to the power signal measured from the wind turbine. However, since the power signal is proportional to the cube of the wind speed, typical wind speed variations lead to significant variations in the performance of the ESC algorithm thereby making the behavior of the control system with the ESC dramatically inconsistent and extremely sensitive to inevitable changes in wind speed. This limits the use and value of the ESC algorithm for finding the most efficient point of operation.

Therefore, it is desirable to have a method and system that take into account at least the issues discussed above, as well as other possible issues.

SUMMARY

An embodiment of the present disclosure provides a method for optimizing performance of a control system. The method comprises using a sensor to generate a feedback signal that represents a measured performance index for an extremum seeking control (ESC) method and sending the feedback signal to an ESC conditioning circuit; using the ESC conditioning circuit to apply a logarithmic transformation to the feedback signal to obtain a modified feedback signal and sending the modified feedback signal to an ESC controller; using the ESC controller to apply the modified feedback signal to the ESC method; and controlling at least one actuator according to an output value generated by the ESC controller.

Another embodiment of the present disclosure provides a control system comprising a sensor configured to generate a feedback signal that represents a measured performance index for an extremum seeking control (ESC) method; an ESC conditioning circuit configured to apply a logarithmic transformation to the feedback signal to obtain a modified feedback signal; an ESC controller configured to apply the modified feedback signal to the ESC method; and at least one actuator controller configured to control an actuator according an output value generated by the ESC controller.

The features and functions can be achieved independently in various embodiments of the present disclosure or may be combined in yet other embodiments in which further details can be seen with reference to the following description and drawings.

