Time delay margins computation for stability of load frequency control in hybrid renewable energy power generation/storage system

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In load frequency control (LFC), it is important to transmit control signals from remote terminal units (RTU) to the control center and from the control center to the plant side. Therefore, time delays in signal transmission become unavoidable. These delays reduce the dynamic performance of the LFC system. This paper is dedicated to the delay-dependent stability analysis of the LFC scheme for renewable energy power generation subsystem. The delay margin of the system is analyzed theoretically for different values of inertia, damping factor as well as controller gains. Theoretically obtained results are compared with simulation studies. The relation between the controller gain and the delay margin is investigated. The system studied includes photovoltaic system (PV), ultra-capacitor (UC) bank for energy storage, wind turbine generator (WTG), diesel generator (DG) and fuel cell (FC) system. The upper bound of the delay time, while LFC system is in stable condition, is known as delay margin. Delay margin computations are realized by using an analytical method approach. Proportional-integral (PI) controller is used for controlling proposed power generation storage system. PI Controller parameters are chosen in a wide range to observe the effect of the parameter space on delay margin variation. Simulation studies verify the effectiveness of the proposed method.