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

Abstract

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.

Stability analysis of network-controlled DC position servo system with time-delay

“…Hence, TD affects the stability of the overall closed-loop control system. This naturally leads to doing an investigation of the effect of TD on the system's stability [6][7][8][9][10][11][12][13].…”

“…Various stability results for TD systems under different delay effects have been reported in [1][2][3][4][5][6][7][8][9][10][11][12][13][29][30][31][32][33][34][35][36][37]. To the best of the authors' knowledge, only a few kinds of literature discuss the effect of TD in stability analysis of DC position servo systems [1,[26][27][28].…”

Neural network based heuristic fractional order adaptive PID‐controller for eliminating communication time delay in multi‐area LFC

“…For instance, control parameters that can keep the system stable for a certain time delay value were determined by Sönmez et al in 2016 16 . The largest time delay values were found for different controller parameters by Khalil et al in 2018 17 . The maximum time delays that can keep the system stable by adding phase and gain margins to different systems were again calculated by Sönmez et al in 2019 18 .…”

“…16 The largest time delay values were found for different controller parameters by Khalil et al in 2018. 17 The maximum time delays that can keep the system stable by adding phase and gain margins to different systems were again calculated by Sönmez et al in 2019. 18 In the same year, the effect of different time delays was analyzed by Shen et al 19 Again in 2019, Sharma et al proposed a controller design by adding the communication time delay in the load-frequency control model.…”