Comment on "Optimal tuning of sigmoid PID controller using nonlinear sine cosine algorithm for the automatic voltage regulator system"

Debdoot Sain; Manoranjan Praharaj; Jung-Min Yang

doi:10.1016/j.isatra.2023.10.005

Comment on "Optimal tuning of sigmoid PID controller using nonlinear sine cosine algorithm for the automatic voltage regulator system"

ISA Trans. 2023 Dec:143:740-744. doi: 10.1016/j.isatra.2023.10.005. Epub 2023 Oct 10.

Authors

Debdoot Sain¹, Manoranjan Praharaj², Jung-Min Yang³

Affiliations

¹ School of Electronic and Electrical Engineering, Kyungpook National University, 80 Daehakro, Bukgu, Daegu 41566, Republic of Korea. Electronic address: saindebdoot@knu.ac.kr.
² Department of Electrical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India. Electronic address: praharaj@iitkgp.ac.in.
³ School of Electronic and Electrical Engineering, Kyungpook National University, 80 Daehakro, Bukgu, Daegu 41566, Republic of Korea. Electronic address: jmyang@knu.ac.kr.

PMID: 37845096
DOI: 10.1016/j.isatra.2023.10.005

Abstract

In this short note, the relative stability results (based on root locus and Bode analyses) reported in "Optimal tuning of sigmoid PID controller using nonlinear sine cosine algorithm for the automatic voltage regulator system" (Suid and Ahmad, 2022) are analyzed. It is shown that the use of closed-loop transfer functions (CLTFs) should be avoided in relative stability analysis since they may lead to less accurate stability results. The present study affirms that the results of relative stability analysis obtained using loop transfer functions (LTFs) are more reliable and accurate.

Keywords: Automatic voltage regulator (AVR); Bode plot; PID controller; Relative stability analysis; Root locus.