Imperialist competitive algorithm optimized cascade controller for load frequency control of multi-microgrid system

Abstract

ABSTRACT Control of multi-energy source-based microgrid is a complex task due to the presence of unpredictable renewable energy sources (RES). This paper proposes a cascade structure of proportional derivative with (1+ PI) controller (C-PDF(1+ PI)) for load frequency control of an AC multi Micro-grid (MG). The MG contains a thermal power unit, Diesel Engine Generator (DEG), Micro Turbine (MT), Fuel Cell (FC), and uncontrolled solar and wind sources. Diverse storage device units like Battery Energy Storage System (BESS), Fly Wheel Energy Storage System (FESS), and Electric Vehicles (EV) are also included in the studied MG system. The proposed C-PDF(1+ PI) controller consists of a first stage Proportional Derivative controller with filter (PDF) and one plus proportional-integral (PI) controller in the second stage. The Imperialist Competitive Algorithm (ICA) is applied to optimize the controller parameters. To confer superiority of the C-PDF(1+ PI) controller, its responses are related with PI, PID, and PIDF controllers. It is observed that the ITAE improvement in percentage with the proposed approach is 70.64%, 53.23%, and 47.10% compared to PI, PID, and PIDF controller while considering the simultaneous variations in load, solar, and wind powers. To justify the efficacy of the ICA technique, it is compared with other well-established techniques like the Genetic algorithm (GA) and the Cuckoo Search algorithm (CSA). It is observed that for the identical system and C-PDF(1+ PI) controller, the ITAE value improvement in percentage by ICA compared to GA and CSA are 31.94% and 15.93%, respectively, while considering all the three uncertainty like changes in load condition, change in solar power irradiation and changes in wind power conditions. Finally, it is conferred that the proposed ICA optimized C-PDF(1+ PI) controller significantly improves microgrid dynamic performance under various operational conditions.