Enhance Selectivity of Cross Differential Relay for Parallel Lines Connecting Solar Photovoltaic Plant

Abstract

Cross differential relay is used for protecting parallel lines. For such lines connecting a solar PV plant to the grid, the current modulation by the plant during fault affects the selectivity of conventional cross differential relay. This work proposes a modified cross differential technique using positive sequence currents and prefault voltage at local bus for protection of parallel lines connecting PV plant. Performance of the proposed method is tested for different fault conditions in PV integrated IEEE-9 bus system.