Flatness-based active disturbance rejection control for linear systems with unknown time-varying coefficients

Abstract

A flatness-based active disturbance rejection control approach is proposed to deal with the linear systems with unknown time-varying coefficients and external disturbances. By selecting appropriate nominal values for the parameters of the system, all the deviation between the nominal and actual dynamics of the controlled process, as well as all the external disturbances can be viewed as a total disturbance. Based on the accurately estimated total disturbance with the aid of the proposed extended state observer, a linear proportional derivative feedback control law taking into account the derivatives of the desired output is designed to eliminate the effect of the total disturbance on the system performance. Finally, the load frequency control problem of a single-area power system with non-reheated unit is employed as an illustrative example to demonstrate the effectiveness of the proposed approach.

Keywords:

• Linear system
• time-varying coefficients
• extended state observer
• flatness
• active disturbance rejection control

Acknowledgements

The anonymous reviewers' insightful comments and valuable suggestions are also greatly appreciated.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work is supported by the National Natural Science Foundation of China [grant no. 61304041]; the Beijing Higher Education Young Elite Teacher Project [grant no. YETP0703]; and supported by ‘the Fundamental Research Funds for the Central Universities’ [2014MS22].