**5. Conclusions**

In this article, directed at the influence of large-scale wind power integration on the security and stability of power system, and considering the impact of communication delay on this system, an ADRC method with EID compensation was applied to maintain the frequency stability of a time-delay power system with a wind farm. The LFC system model was established, and simulation results validated the effectiveness and superiority of the proposed control method. The disturbance in real time can be estimated and compensated with the control strategy based on EID. Finally, by comparing with traditional LFC methods, the simulation results show that the proposed ADRC method has a significantly higher performance at solving frequency instability under various types of load variations. The EID-based ADRC strategy can quickly and effectively suppress the influence of external disturbances on the frequency of power system.

**Author Contributions:** All the authors made contributions to the concept and design of the article; F.L. is the main author of this work. R.Z. provided good advice and technical guidance for the manuscript; F.L., K.Z. and R.Z. reviewed and polished the manuscript.

**Funding:** This work was supported by the Natural Science Foundation of China (NSFC) under Grant 61673398, in part by Natural Science Foundation of Hunan Province of China under Grant 2018JJ2529, and in part by the Huxiang Youth Talent Program of Hunan Province under Grant 2017RS3006.

**Conflicts of Interest:** The authors declare no conflict of interest.
