This paper presents a computer model for planning the optimal electric energy purchasing by Brazilian distribution utilities. The goal of the model is to find the least energy purchase cost, in short/very short term, in order to fully meet the commitments of energy supply to utility's consumers, according to the current regulatory conditions and taking into account distributed generation. The model assesses regulatory and market peculiarities and constraints related to the Brazilian Electric Power Sector, as well as the technical limits of distributed generation units ratings. The proposed objective function includes short term market, penalties for insufficient energy contracting by the distribution utility, adjustment biddings and distributed generation units connected to the utility network. Fuzzy Linear Programming was used in order to provide a better treatment to the uncertainties inherent to the process, such as demand forecasting or high variability of wind power generation. The proposed methodology was tested for a Southeastern Brazilian distribution utility. Parametric variations of costs and tariffs, for the contracting alternatives, were carried out to investigate the economical feasibility of distributed generation inclusion on the global energy purchase costs of the distribution utility. The results showed successful coherence with the objective of minimum cost model, as expected.
Energy Purchasing; Distributed Generation; Load Forecasting; Fuzzy Linear Programming
