DETERMINATION OF A MINIMUM PROTECTIVE SYSTEM FOR DISTRIBUTION SYSTEMS EMBEDDED WITH SMALL SOURCES OF DISTRIBUTED GENERATION

In last years, the Brazilian electric sector is watching an increased growing in the participation of distributed generation (DG) sources. Mainly, at voltage levels of 23 kV and 13.8 kV, typical for grid medium voltage, the impacts caused by low power generators may lead to several technical and economical problems. Fault levels alteration, distribution system instability, islanding in parts of the system and increased interruption duration are some of these problems. Hence, this paper treats about the effects produced by the insertion of low power DG sources in the distribution system, particularly of synchronous machines. In the future, the results obtained here could be used to help determining a standard protective system and to decide about the decisions to be taken over DG installation to prevent them to represent any harm to the distribution system. The considerations and results presented in this paper are part of a Research & Development Program of the State Company of Electric Energy (CEEE-D) and executed by the Federal University of Santa Maria (UFSM).