Designing automatic load frequency control scheme for Sri Lankan power system

Abstract

The Sri Lankan power grid is being operated at nominal frequency which is 50 Hz and steady state regulation window is 49.50 Hz to 50.50 Hz. There will be a frequency error left behind, during either demand or generation change as per system dynamics. Such error is generally corrected by secondary control regulation which is mainly done by verbal dispatch instruction originated from system control center. Hence, the regulation quality of grid frequency is highly depended on above said manual frequency corrective action which is executed by the Control Room Operator(CRO) back in the related power plants. The amount of frequency deviations within the operational limit, have been increased significantly during the last couple of years in Sri Lankan system. The aim of this study is to design and analyse the Automatic Load Frequency Control(ALFC) scheme for regulating secondary control spinning reserves based on persisting Area Control Error(ACE) values. Hence, MATLAB Simulink models are developed for primary and secondary regulations while addressing the unique constraints related to frequency regulation of Sri Lankan power system. Consequently, both the models are combined and the behavior of system frequency response with ALFC is studied in detail for different generation scenarios. The outcomes direct that, how exactly ALFC could be implemented in Sri Lankan power system while exhibit the enhancement of frequency regulation quality. The designed model and obtained results during this study could be used as base-case platform for implementation or further study of ALFC methodology for Sri Lankan power system.