Frequency Regulation of a Standalone Interconnected AC Microgrid Using Innovative Multistage TDF(1+FOPI) Controller

This paper's main purpose is to offer an innovative multistage controller for load-frequency regulation of a standalone interconnected microgrid (SMG). A multistage TDF(FOPI+1) controller is designed, with the first stage being a filter built of the tilting and derivative operators. Transferring the integrator component to the second stage of the controller and employing its fractional-order (FO) form as a FO proportional-integrator (FOPI) controller results in the latter stage of the controller. To calculate the optimal controller parameters, the recently introduced Bonobo optimization algorithm (BOA) is applied. Besides, the optimization objective function is a mix of the control error signal in each area and the dynamic response characteristics of the system. In complex operating conditions such as sudden changes in power demands, uncertainties in renewable energy units' output, considering nonlinear factors, and parametric uncertainties in a two-area SMG, the performance of the proposed controller is compared with classical and multistage controllers. The results show that the TDF(1+FOPI) controller has a competent dynamic response and can be a suitable choice for performing LFC duties in SMGs. This control strategy's advantages include enhanced controller resistivity in diverse circumstances, faster reaction times, and better dynamic behavior. The results of the five studied scenarios show that using the proposed control strategy, the value of the objective function is improved by an average of more than 50% compared to other classical and conventional controllers. Similarly, improvements of more than 70% and 50% in key integral of time-weighted square error (ITSE) and Integral of absolute error (IAE) time zone indicators, respectively, are among the results of these studies.