An Adaptive Current Protection Scheme for Distribution Network Connected to DG

Aiming at the problem of insufficient reliability after distributed power supply is connected to the distribution network, this paper proposes an adaptive directional current protection scheme based on fault steady-state component. By analyzing different kinds of DG fault transient characteristics and equivalent methods, the types of various components in the system fault current are analyzed. Based on this, according to the fault boundary conditions, combined with the voltage and current measured at the protection location, the equivalent voltage and equivalent impedance of the back side of the system are calculated, and the adaptive direction current protection judgment under different fault types, positions and different DG capacities is constructed. The simulation results show that the method is not affected by the DG type, and has strong adaptability. It is sensitive to the delay protection caused by voltage drop.