Automatic load shedding (ALS) is categorized as one of the protection systems applied to a power network. The aim of this work is to understand how the system works by creating a software simulation of the above-mentioned system. Prerequirement to this is the need to understand the electrical system response to the presence of disturbances and interruptions on over loads. A case study on University Teknologi Petronas Gas District Cooling (UTP GDC) cogeneration power plant has also been carried out. The plant has implemented load shedding scheme as one of their power reliability strategy. The plant has 4 stages of load shed and a single frequency set point to trigger the under-frequency relay. Simulation results were obtained using PSCAD/EMTDC to prove the effectiveness of the system. © 2003 IEEE.