Stability regions in time delayed two-area LFC system enhanced by EVs


Naveed A., Sonmez S., AYASUN S.

TURKISH JOURNAL OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCES, vol.30, no.1, pp.249-263, 2022 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 30 Issue: 1
  • Publication Date: 2022
  • Doi Number: 10.3906/elk-2104-113
  • Journal Name: TURKISH JOURNAL OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCES
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Applied Science & Technology Source, Compendex, Computer & Applied Sciences, INSPEC, TR DİZİN (ULAKBİM)
  • Page Numbers: pp.249-263
  • Keywords: Communication delays, electric vehicles, load frequency control, PI controller, stability region, LOAD FREQUENCY CONTROL, DEPENDENT STABILITY, POWER-SYSTEMS, COMPUTATION, PI, AGGREGATORS, CONTROLLERS, CONSTANT, MARGINS, DESIGN
  • Gazi University Affiliated: Yes

Abstract

With the extensive usage of open communication networks, time delays have become a great concern in load frequency control (LFC) systems since such inevitable large delays weaken the controller performance and even may lead to instabilities. Electric vehicles (EVs) have a potential tool in the frequency regulation. The integration of a large number of EVs via an aggregator amplifies the adverse effects of time delays on the stability and controller design of LFC systems. This paper investigates the impacts of the EVs aggregator with communication time delay on the stability. Primarily, a graphical method characterizing stability boundary locus is implemented. The approach is based on the stability boundary locus that can be easily determined by equating the real and the imaginary parts of the characteristic equation to zero. For a given time delay, the method computes all the stabilizing proportional-integral (PI) controller gains, which constitutes a stability region in the parameter space of PI controller.The effects of communication delay and participation factor of EVs aggregator on the obtained stability regions is thoroughly examined. Results clearly illustrate that stability regions become smaller as the time delay and participation factor of EVs increase. Finally, the accuracy of region boundaries known as real root boundary and complex root boundary is confirmed by time-domain simulations along with an independent algorithm, quasipolynomial mapping-based root finder (QPmR) algorithm.