Mohammad Taghi Farahnak - Department of Industrial Management, Central Tehran Branch, Islamic Azad University, Tehran, Iran.
Mohammad Ali Afshar Kazemi - Department of Industrial Management, Central Tehran Branch, Islamic Azad University, Tehran, Iran.
Ali Mohaghar - Department of Industrial management, Faculty of Management, University of Tehran, Tehran, Iran.
Mohammad Ali Keramati - Department of Industrial Management, Central Tehran Branch, Islamic Azad University, Tehran, Iran.

This research models and simulates the development of transmission capacity considering electricity supply and demand dynamics. After presenting a causal loop diagram and designing a stock and flow diagram, the model's validity is confirmed using validation methods for system dynamics models. The analysis then proceeds to scenarios for the total electricity demand in Iran. Firstly, the country's electricity demand structure is broken into industrial, household, agricultural, and other sectors. By studying consumption trends in each sector, linear and nonlinear regression are used to predict total electricity demand. Next, three scenarios - optimistic, moderate, and pessimistic - are defined in terms of electricity demand, and the required transmission capacity is calculated and designed for ۴۰۰, ۲۳۰, ۱۳۲, and ۶۳-۶۶ kilovolt substations to cover and meet future electricity demand over twenty years. The research findings over a ۲۰-year horizon indicate that in the moderate scenario, where electricity demand increases by ۹۰ percent, the transmission capacity needs to increase by ۱۰۶ percent to meet the demand. In the optimistic scenario, where electricity demand increases by ۷۱ percent, the transmission capacity needs to increase by ۸۵ percent. In the pessimistic scenario, where electricity demand increases by ۱۱۰ percent, the transmission capacity needs to increase by ۱۲۶ percent.

System dynamics, Power transmission capacity, Expected power demand, Power transmission capacity development