Enhancing stability region of time-delayed smart power grids by non-integer controllers

Abstract

In this study, the impacts of non-integer order controller on the stable parameter space of the microgrid (MG) frequency control system with fixed communication time delay are investigated and discussed with the help of the stability boundary locus (SBL) method. This study proposes a non-integer order controller for the load frequency control (LFC) of the MG systems. To that end, the load frequency model of the MG is formulated and then the characteristic equations of this model are obtained. Then, with the help of this characteristic equation, the stable parameter space of the non-integer controller is determined with regard to different time delay (τ) and fractional integral order values (α) using the SBL method. In order to show the accuracy of the obtained stable parameter space, time domain and generalized modified Mikhailov (GMM) criterion studies are carried out for different values of (τ) and (α). According to the results obtained, the areas of stable parameter space according to different α values and τ = 1.6 are calculated as 444.8860 for α = 0.4, 342.9728 for α = 0.7, 259.3578 for α = 1, 216.2541 for α = 1.3 and 159.6826 for α = 1.6. In addition, the areas of stable parameter space according to different τ values and α = 1.4 are calculated as 784.5222 for τ = 1, 106.3219 for τ = 2, 29.6959 for τ = 3 and 11.5946 for τ = 4. Despite the extreme variability arising from nature of resources that make up the MG, the designed non integer order controller with the values selected within the stable parameter space stably carries out LFC control of the MG. © 2020 John Wiley & Sons Ltd