Protection Scheme Based on Fault Area Estimation in Loop-Type Low Voltage DC Distribution System with Photovoltaic System using Derivative of Current and Power at Tie Switch

DC power distribution technologies have recently been attracting attention for numerous reasons such as increases in DC-based renewable energy systems and loads, and decreases in loss due to reductions in AC/DC conversion in line with efforts to achieve carbon neutrality. For stable and reliable operation of a DC distribution system, analyzing the system impact and developing countermeasures for when a fault occurs. Therefore, in this study, the fault characteristics of a loop-type low-voltage DC (LVDC) distribution system with a photovoltaic (PV) system are analyzed, and a new protection scheme based on fault area estimation is proposed. In a loop-type LVDC distribution system, several distribution lines are connected by a tie switch. The proposed scheme calculates the power using the current and voltage flowing through the tie switch. The algorithm determines the fault area using the derivative of the current and power at the tie switch, and controls the circuit breaker (CB) operation accordingly. To evaluate the proposed method, the LVDC distribution system and the proposed protection scheme are modeled using the Electromagnetic Transients Program/ATPDraw, and various simulations are performed based on the type and area of the fault. The simulation results show that the fault area is accurately determined and that outages can be reduced by the proper operation of the CB.