An Exact Method for Computing Delay Margin for Stability of Load Frequency Control Systems With Constant Communication Delays

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.

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Stability criteria for load frequency control systems with communication delays and packet dropout

2016 IEEE 1st International Conference on Power Electronics, Intelligent Control and Energy Systems (ICPEICES) ◽

10.1109/icpeices.2016.7853540 ◽

2016 ◽

Cited By ~ 3

Author(s):

Pankaj Dahiya ◽

Pankaj Mukhija ◽

Anmol Ratna Saxena

Keyword(s):

Control Systems ◽

Frequency Control ◽

Load Frequency Control ◽

Packet Dropout ◽

Communication Delays ◽

Stability Criteria ◽

Load Frequency

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

10.20944/preprints201810.0146.v1 ◽

2018 ◽

Author(s):

Ashraf Khalil ◽

Ang Swee Ping

Keyword(s):

Time Delay ◽

Control Systems ◽

Frequency Control ◽

Pi Controller ◽

Load Frequency Control ◽

New Method ◽

Open Communication ◽

Load Frequency ◽

The Stability ◽

Delay Margin

The open communication is an exigent need for future power system where the 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. The load frequency control signals are transmitted through communication networks which induces time delay that could destabilize the power systems. So, in order to guarantee the 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 to frequency dependant equation. The spectral radius is used to find the frequencies at which the roots crosses the imaginary axis. The crossing frequencies are determined through the sweeping test and the binary iteration algorithm. A one-area load frequency control system is chosen as case study. The effectiveness of the proposed method has been proved through comparing with the most recent published methods. The method shows its merit with less conservativeness and less computations. The PI controller gains are preferable to be chosen large to reduce the damping, however, the delay margin decreases with increasing the PI controller gains.

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