Avaliação do desempenho dos relés de proteção anti-ilhamento em um sistema com geração distribuída

Abstract

Distributed generation, i.e., the connection of generators to the subtransmission/distribution system of power utility companies have grown enormously in Brazil and around the world. Parallel to this growth, standards and technical recommendations which establish minimum requirements for connecting new producers of electricity to the electrical system. The connection of distributed generation affects the electrical system in several ways. One of the situations that arise with inclusion of distributed generation in the system is the possibility that some loads connected to electric generators remain connected upon the occurrence of contingencies in the utility system, creating a condition called islanding. The islanding is currently not allowed by most power utilities companies in many countries, including Brazil, because this configuration puts in risk the safety of people and equipment beyond deteriorate the quality of power supplied to local consumers. Faced with this context, this work is intended to evaluate two protections for anti-islanding, the phase shift relay and the rate of change of frequency relay as well, which are gaining interest of energy producers due to its low cost compared with other protection systems, and due to their ease of installation. Therefore this study evaluates the effectiveness of these relays in employment in a specific system with distributed generation, showing the difficulties encountered in their widespread use.