Abstract: This paper proposes a new methodology to explicitly consider unreliability costs in a multi-stage transmission expansion planning. Starting from a reference plan, alternative expansion plans are derived based on postponement/anticipation of circuit implementations. These plans are then ranked by using an economic index of merit (EIM) and the associated Pareto-optimal set is obtained through cost/benefit (trade-off) analyses. The cost/benefit is related to the variation of investments and operational costs of each alternative transmission plan. Besides the usual operational costs (active power losses, fuels, etc.) the unreliability costs, due to random failures in the system, are also considered as operational costs. Therefore, reliability evaluations are carried out for all transmission expansion plans (TEPs) in order to compute reliability indices, such as the Expect Energy not Supplied and Loss of Load Cost (LOLC). To reduce the computational effort, pruning techniques are used to limit the number of possible TEPs. The proposed approach is applied to a configuration of the Brazilian North-eastern system, considering a planning horizon of 10 years, to identify TEPs that are more balanced in terms of investment and reliability.

Abstract: Post dispatch analysis of signals obtained from digital disturbances registers provide important information to identify and classify disturbances in power systems, looking for a more efficient management of the supply. In order to enhance the task of identifying and classifying the disturbances $providing an automatic assessment - techniques of digital signal processing can be helpful. The Wavelet Transform has become a very efficient tool for the analysis of voltage or current signals, obtained immediately after disturbances occurrences in the network. This paper presents a methodology based on the discrete wavelet transform to implement this process. It uses a comparison between distribution curves of signals energy, with and without disturbance. This is done for different resolution levels of its decomposition in order to obtain descriptors that permit its classification, using artificial neural networks

Abstract: The purpose of this paper is to provide information about harmonic voltage and current component measurements in the transmission / sub-transmission system buses of CHESF, federal power utility of northeast of Brazil, in the period of a brazilian game during the world cup of soccer 2006, when a great number of non-linear load (television) was introduced into the power utility systems. Inspired in part by a paper published 20 years ago, in 1987, relating the harmonic levels measured in Fortaleza during the world cup soccer 1986, we decided to perform a new analysis in order to evaluate whether the same effect observed 20 years ago would be repeated in the present day, considering the changes on the electric load characteristic over this period of time.