Análise do impacto da geração distribuída na proteção dos sistemas de transmissão e distribuição de energia elétrica

Abstract

The change of philosophy of Brazilian power electric system has brought new challenges for the sector. The old power plants, in which there were almost only large power plants built far away from consumers, has been modernized and extended by many small generators scattered throughout the system and closer to consumers. These small generators installed in a decentralized manner, are called distribuited generators, or Distribuited Generation. To ensure the continuous supply of energy, it is necessary to use an electrical protection system that eliminates a fault quickly and accurately, isolating the defect in the smallest possible area ( concept of selectivity ). It is known that for this it is necessary that the electrical system is studied in detail, considering generators, loads, transmission and distribution lines, so that the protections are parameterized correctly. The Distributed Generation can significantly impact the power flow and voltage conditions on consumers and transmission and distribution systems. This requires a detailed system assessment in order to define the impact of Distributed Generation in this system, to ensure the correct parameterization and performance of the protection system. The industry that has power generation, ie, generating very close to its consumers, has suffered constant tripping of its protection system due to defects in various parts of the Brazilian Electric System. The energy self-producer industry has the ability to continue at normal operation even after the tripping of protection that separates itself from the faulty Brazilian electrical system. Right now, when losing the reference system, the level of short circuit in the industry high voltage bars falls considerably, up to 40%, and protection system that is well adjusted to the condition connected with the Brazilian electrical system may be vulnerable. This work aims to analyse the influence of Distributed Generation in the functioning of protection systems of substations and transmission lines of the National Interconnected System by analysis of two cases: 1. A Study on a generic network to determine which protection should be used to enhance the continuity of the system, or part thereof, for a fault at any point after the connection of Distributed Generation; 2. A specific Case Study regarding to the behavior of the industrial electric protection system in several operational conditions of generation.