Interconnected systems with critical infrastructures can be affected by small failures that may trigger a large-scale cascade of failures, such as blackouts in power grids. Vulnerability indices provide quantitative measures of a network resilience to component failures, assessing the break of information or energy flow in a system. Here, we focus on a network vulnerability analysis, that is, indices based solely on the network structure and its static characteristics, which are reliably available for most complex networks. This work studies the structural connectivity of power grids, assessing the main centrality measures in network science to identify vulnerable components (transmission lines or edges) to attacks and failures. Specifically, we consider centrality measures that implicitly model the power flow distribution in power systems. This framework allow us to show that the efficiency of the power flow in a grid can be highly sensitive to attacks on specific (central) edges. Numerical results are presented for randomly generated power-grid models and established power-grid benchmarks, where we demonstrate that the system’s energy efficiency is more vulnerable to attacks on edges that are central to the power flow distribution. We expect that the vulnerability indices investigated in our work can be used to guide the design of structurally resilient power grids.
Distribution transformers are responsible for approximately one third of the electric system losses. The capitalized losses may represent significant costs to the utility and to society itself. Therefore, great effort has been directed to increasing the efficiency of distribution transformers and consequently reducing the losses and, hence, the operational costs. International standards, published by means of norms, define the power efficiency of transformers, taking into account the no-load losses, the load losses and capitalization equations. An increase in distributor efficiency is obtained through prior knowledge of loads and design adequateness. The objective at AES-Sul Utility Company is to offer the best service to its customers through knowledge of their system and also through the acquisition of efficient equipment, compatible with similar units presently available in the European Common Market.
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