Short Term Load Forecasting for Utility System using Fuzzy Logic Approach

The main objective of Short Term Load Forecasting (STLF) is to provide load predictions for generation scheduling, economic load dispatch and security assessment at any time. In this paper the 'time' of the day and 'temperature of the day are taken as inputs for the fuzzy logic controller and the 'forecasted load' is the output. The input variable 'time' has been divided into eight triangular membership functions. The membership. functions are Mid Night, Dawn, Morning, Fore Noon, After Noon, Evening, Dusk and Night. Another input variable 'temperature" has been divided into four triangular membership functions. They are Below Normal, Normal, Above normal and High. The 'forecasted load' as an output has been divided into eight triangular membership functions. They are Very Low, Low, Sub Normal, Moderate Normal, Normal, Above normal, High and Very High. Case studies have been carried out for State Electricity System (SES), which is the utility system in India. The results are compared with the conventional controller and fuzzy controller. It is found that the fuzzy controller is more effective, economical and having lower forecasted value than the conventional controller. This fuzzy approach is much closer to people's decision-making process in real life.