A New Method for Computing the Delay Margin for the Stability of Load Frequency Control Systems

Ashraf Khalil and Ang Swee Peng
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Ashraf Khalil: Electrical and Electronic Engineering Department, Universiti Teknologi Brunei, Jalan Tungku Link, Gadong BE1410, Brunei Darussalam
Ang Swee Peng: Electrical and Electronic Engineering Department, Universiti Teknologi Brunei, Jalan Tungku Link, Gadong BE1410, Brunei Darussalam

Energies, 2018, vol. 11, issue 12, 1-18

Abstract: Open communication is an exigent need for future power systems, where time delay is unavoidable. In order to secure the stability of the grid, the frequency must remain within its limited range which is achieved through the load frequency control. Load frequency control signals are transmitted through communication networks which induce time delays that could destabilize power systems. So, in order to guarantee stability, the delay margin should be computed. In this paper, we present a new method for calculating the delay margin in load frequency control systems. The transcendental time delay characteristics equation is transformed into a frequency dependent equation. The spectral radius was used to find the frequencies at which the root crosses the imaginary axis. The crossing frequencies were determined through the sweeping test and the binary iteration algorithm. A one-area load frequency control system was chosen as a case study. The effectiveness of the proposed method was proven through comparison with the most recent published methods. The method shows its merit with less conservativeness and less computations. The impact of the proportional integral (PI) controller gains on the delay margin was investigated. It was found that increasing the PI controller gains reduces the delay margin.

Keywords: communication time delays; delay margin; delay dependent stability; load frequency control system; sweeping test (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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