Development of New Protection System Using Direction of Fault Current in Radial-Type LVDC Distribution System with PV System

As a response to the goal of achieving carbon neutrality, there is growing interest in low voltage direct current (LVDC) distribution systems combined with photovoltaic (PV) systems. This interest stems from their ability to connect PV systems, accommodate increased DC loads, and reduce losses associated with AC/DC conversion. To ensure the stable operation of LVDC systems, the development of protective measures against transients is crucial. This paper proposes a novel protection method for LVDC systems with PV. It examines potential mal-operations of protection relays and coordination issues based on fault locations. Using the direction of the fault current, the proposed protection method determines the fault location within the circuit breaker (CB) of the distribution line and adjusts CB control accordingly. To validate the proposed method, the LVDC system is modeled using EMTP/ATPDraw, and various simulations are conducted based on different fault locations. The simulation results demonstrate that accurate fault location determination and CB control can effectively reduce power outage areas, preventing protection relay mal-operations and coordination problems.