https://iaeme.com/Home/journal/IJEET 178 editor@iaeme.com International Journal of Electrical Engineering and Technology (IJEET) Volume 12, Issue 7, July 2021, pp. 178-186, Article ID: IJEET_12_07_018 Available online at https://iaeme.com/Home/issue/IJEET?Volume=12&Issue=7 ISSN Print: 0976-6545 and ISSN Online: 0976-6553 DOI: https://doi.org/10.34218/IJEET.12.7.2021.018 © IAEME Publication Scopus Indexed A ROBUST LOAD-FREQUENCY CONTROL STRATEGY FOR HYDROPOWER PLANTS AFFECTED BY UNCERTAINTIES Ngoc-Khoat Nguyen Researcher, Faculty of Control and Automation, Electric Power University, Hanoi, Vietnam ABSTRACT Hydroelectric power plants are being widely distributed all over the world today. One of the most important control problems in such power stations is load-frequency control which mainly aims to maintain the system frequency at a nominal value (50Hz or 60Hz). When designing a load-frequency controller, it is highly necessary to consider a number of real uncertainties relating unknown parameters which absolutely strongly affect normal operation of the system. Traditional load-frequency controllers i.e. integral and proportional plus integral regulators cannot guarantee the control quality of the system due to negative influences of the uncertainties. Intelligent controllers have been invented as effective control strategies to replace with these traditional counterparts. This study focuses on designing a promising control candidate using fuzzy logic to deal with the load – frequency control in case of appearing lots of uncertain parameters. Control results obtained using MATLAB/Simulink package in an isolated hydropower plant model for various simulation cases of load changes suitable for the reality demonstrate the applicability of the proposed control scheme over conventional PID regulator. Key words: hydroelectric power plant, uncertainties, PID, fuzzy logic controller. Cite this Article: Ngoc-Khoat Nguyen, A Robust Load-Frequency Control Strategy for Hydropower Plants Affected by Uncertainties, International Journal of Electrical Engineering and Technology (IJEET), 12(7), 2021, pp. 178-186. https://iaeme.com/Home/issue/IJEET?Volume=12&Issue=7 1. INTRODUCTION It is known that an actual control plant is usually characterized by a lot of uncertain parameters. Naturally, the uncertainties may appear in every system during its operation. In this perspective, the uncertainties randomly occur in the system as either unknown or bounded changing parameters. It is technical the uncertain parameters are also embedded when a plant model is built from an experiment data set obtained by an identification method. This scenario leads a mathematical model of the control plant represented by a transfer function together with a