Abstract:
The Brazilian distribution systems have experimented a profound change since the
conditions for inserting new sources of electric power in these systems called mini and micro
distributed generation were standardized. These sources, composed of different types of
technologies such as Wind Power, Photovoltaic, Hydroelectric and Thermoelectric Power
Plants have grown at a rapid pace from 6 connections in 2012 to more than 300,000 in 2020.
Despite the benefits of using distributed generation (DG) for the electrical system, with
the reduction of electrical losses in distribution, and for customers, with the possibility of using
credits with surpluses generated, the use of these different generation technologies unleashes
discussions about its impacts on the system.
Among the impacts, we can emphasize those related to the protection systems in the
distribution lines that directly affect the reliability of the energy supply to customers, and can
even turn into fines for the utilities.
Regarding the classic methodologies for protecting distribution lines, consisting of
selective and coordinated protection philosophies, which take into account their predominance
of radial configuration, with the presence of a single source, the presence of the distributed
generation changes the dynamics events in these systems and thereby make current protection
methodologies obsolete, requiring the application of dynamic and more adaptable
methodologies.
Considering the above, the present work proposes a study of the impacts of distributed
generation for the classical protection of electrical power distribution systems and the proposal
of a protection methodology aiming at the optimization and correct performance of the
protection system. The proposed methodology aims to obtain optimized protection settings that
attend to the different operating scenarios of the system with DG, maintaining selectivity and
coordination among equipment and allowing the increase of system reliability.
This evaluation will be done through a case study, using specific software for distribution
protection studies, where the real characteristics of a feeder from an important Brazilian Utility
that has a connection with distributed generation through hydroelectric power were modeled.
The developed study evidences the significant influence of DG on the distribution systems
protection, with more significant impacts in the coordinated protection philosophy.UNIFEI – UNIVERSIDADE FEDERAL DE ITAJUBÁ
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Furthermore, it is verified that the application of the protection settings determined through the
proposed methodology reduces the impacts of the entry of DG in the system by approximately
49% when compared to the system with conventional protection methodology applied,
maintaining the selective and coordinated philosophies in the different operating scenarios.