Aydin, Omer; Hasen, Suud Ademnur; Ayasun, Saffet

The share of renewable energy sources (RES) in power systems is rising due to environmental concerns. This increment leads to the lack of inertia and insufficient damping which pose a significant threat for frequency stability and dynamic performance of load frequency control (LFC) systems. Various methods have been employed to overcome this drawback. One of these is the utilization of electric vehicles (EVs) for frequency regulation. Furthermore, in practice, systems do not always operate under identical conditions. Therefore, parametric uncertainties should be considered in controller design. This paper applies Kharitonov's theorem and stability boundary locus method to determine a set proportional-integral (PI) controller gains defined as a robust stability region that ensures the stability of the time-delayed LFC system with EV aggregator having uncertainties in system parameters. The impacts of the level of uncertainties and time delay on the robust stability region are investigated. Results indicate that robust stability regions shrink as the level of uncertainties and time delay increase.

Hocaoglu, Gokce Sena; Cavli, Nazlican; Kilic, Elcin; Danayiyen, Yahya

In this paper, various type of nonlinear convergence factors based Grey Wolf optimization (GWO) is proposed to optimally compute the Proportional-Integral-Derivative (PID) controller gains to control the grid frequency in a single area power system. The PID gains in the controlled system are optimally determined by using GWO algorithm, considering the cost function, integral of time-weighted absolute error (ITAE). The efficiency of the designed control system is verified under constant and variable loads, and the comparative results are given for controlled and uncontrolled cases. Moreover, the GWO algorithm is investigated by using linear and nonlinear convergence coefficients comparatively. The model of the control system is constructed using MATLAB, and the results indicate that the transient and steady state responses are superior to those of the linear coefficients when the nonlinear convergence coefficients are applied in GWO.

Hasen, Suud Ademnur; Aydin, Omer; Ayasun, Saffet

Growing deployment of renewable energy sources (RES) may lead to oscillations in the system frequency caused by reduced inertia, while communication networks generate time delays that might jeopardize system dynamic performance and induce additional frequency fluctuations. This paper presents the optimization of Proportional Integral (PI) controller gains in a time-delayed two-area load frequency control (LFC) system with virtual inertia and damping (VID). Optimization techniques such as Crow Search Algorithm (CSA), Particle Swarm Optimization (PSO), Vortex Search Algorithm (VSA), and Sine-Cosine Algorithm (SCA) are used to optimize the PI controller gains to obtain best frequency performance of the system. In all algorithms, the integral square error (ISE) objective function is employed during the optimization process. Results are confirmed via time-domain simulations in Matlab/Simulink.