Estimated Flatness-Based Active Disturbance Rejection Control for Load Frequency Control of Power Systems

An estimated flatness-based active disturbance rejection control (EF-ADRC) is proposed for the load frequency control (LFC) of power systems in this paper. Different from the traditional ADRC design, the selections of the order and the gain of the flatness-based ADRC controller are based on the flatness output, which is a linear combination of the system states, rather than the nominal integral cascade model. In addition, an extra extended state observer (ESO) is adopted to estimate the system states and the unknown external disturbance. The former is used to replace the actual system states in the flat output, and the latter is used in trajectory planning of the estimated flat output to achieve the unbiased tracking. The proposed method is applied to single-area systems with reheat turbine and hydro turbine, as well as a four-area system, and the simulation results show that the proposed method can achieve satisfactory performance.