Performance evaluation of power swing blocking function and islanding protection - A case study on the Uruguayan network

The Uruguayan electric power system is facing deep challenges. The current and near scenarios include a significant expansion of generation based on renewable sources (wind, biomass) and the opening to multiple, distributed private generators. This paper describes the performance assessment of the protection scheme of a subsystem of the Uruguayan network directly associated to the connection of a big industrial cogenerator involving about 10% of the maximum historical Uruguayan load. The protective scheme contemplates the islanding of this generator when significant, unstable disturbances are present. The focus is on power swings blocking and out-of-step tripping functions of the involved protective relays. The analysis involves time domain simulations and laboratory tests on the relays, to evaluate its performance under power swing conditions.