Wide Area Backup Protection for Network Integrated with Large-Scale Solar Photovoltaic Plant

Over the last decade, there has been a tremendous increase in penetration of solar photovoltaic (PV) energy sources in the power system. The protection algorithms for grids are dependent on the fault current magnitude along with the current flow. With the inverter based solar PV sources, fault current characteristics are different from the conventional sources. The inverters regulate the voltage and current such that they remain fixed within certain limits under different network conditions. As a consequence, the fault current changes with the mode of operation. This paper proposes a wide area measurement based backup protection scheme for distance relays. The method can detect faults and power swing conditions. Impedances calculated from voltage and current signals using data obtained from synchrophasors are used for this purpose. The proposed method is tested using PSCAD simulations in the modified New England 39-bus network. Results for different scenarios such as 3-phase faults, power swing and fault during power swing highlight the performance of the proposed method.